U.S. patent application number 13/257274 was filed with the patent office on 2012-05-10 for electrostatic coating apparatus for electrically conductive coating material.
Invention is credited to Masashi Honma, Hiroki Matsunaga, Daisuke Nakazono, Norihiko Sudo.
Application Number | 20120111268 13/257274 |
Document ID | / |
Family ID | 43529334 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120111268 |
Kind Code |
A1 |
Nakazono; Daisuke ; et
al. |
May 10, 2012 |
ELECTROSTATIC COATING APPARATUS FOR ELECTRICALLY CONDUCTIVE COATING
MATERIAL
Abstract
In an electrostatic coating apparatus (1), an electrically
conductive coating material is supplied through a coating material
supplying path (11) to a coating gun (13) to which a high voltage
is applied. The electrostatic coating apparatus (1) is provided
with an insulating and separating valve (32) capable of
electrically insulating and separating the coating material
supplying path (11) into an application side in which the high
voltage is applied and a non-application side. The insulating and
separating valve (32) is provided with a female coupling member
(32U) having a first connecting portion (54) and a male coupling
member (32D) having a second connecting portion (64). A supplying
hole (55) for supplying a cleaning fluid to the first connecting
portion (54) and the second connecting portion (64) and a
discharging hole (56) for discharging the cleaning fluid supplied
to the first connecting portion and the second connecting portion
are provided on one of the female coupling member (32U) disposed on
the non-application side and the male coupling member (32D).
Inventors: |
Nakazono; Daisuke; (Tochigi,
JP) ; Matsunaga; Hiroki; (Tochigi, JP) ;
Honma; Masashi; (Tochigi, JP) ; Sudo; Norihiko;
(Tochigi, JP) |
Family ID: |
43529334 |
Appl. No.: |
13/257274 |
Filed: |
July 27, 2010 |
PCT Filed: |
July 27, 2010 |
PCT NO: |
PCT/JP2010/062645 |
371 Date: |
September 16, 2011 |
Current U.S.
Class: |
118/621 ;
137/315.01 |
Current CPC
Class: |
B05B 5/1625 20130101;
B05B 5/1675 20130101; B05B 15/55 20180201; B05B 12/14 20130101;
B05B 5/0407 20130101; B05B 12/149 20130101; F16L 45/00 20130101;
B05B 5/1666 20130101; F16L 37/30 20130101; B05B 5/1616 20130101;
Y10T 137/598 20150401 |
Class at
Publication: |
118/621 ;
137/315.01 |
International
Class: |
B05B 5/025 20060101
B05B005/025; B23P 19/04 20060101 B23P019/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2009 |
JP |
2009-177518 |
Jul 31, 2009 |
JP |
2009-179129 |
Jul 31, 2009 |
JP |
2009-179352 |
Claims
1. An electrostatic coating apparatus for an electrically
conductive coating material which supplies the electrically
conductive coating material through a coating material supplying
path to a coating gun to which a high voltage is applied, the
apparatus comprising: an insulating and separating valve capable of
electrically insulating and separating the coating material
supplying path into an application side in which the high voltage
is applied and a non-application side, wherein the insulating and
separating valve include: a female coupling member having a concave
portion serving as one of coupling portions and a first connecting
portion provided on a bottom face of the concave portion and
serving as a connecting portion of the coating material supplying
path; and a male coupling member having a convex portion serving as
the other of the coupling portions to be coupled to the concave
portion and a second connecting portion provided on a tip of the
convex portion and serving as a connecting portion of a passage to
be connected to the first connecting portion, wherein one of the
female coupling member and the male coupling member being provided
on the non-application side and including a supplying hole for
supplying a cleaning fluid to the first connecting portion and the
second connecting portion when the first connecting portion and the
second connecting portion are disposed apart from a position for a
connecting state by a predetermined distance, and a discharging
hole for discharging the cleaning fluid supplied to the first
connecting portion and the second connecting portion, and wherein
the other of the female coupling member and the male coupling
member being provided on the application side.
2. The electrostatic coating apparatus according to claim 1, the
apparatus further comprising: a seal member provided on one of an
outer peripheral part of the convex portion and an inner peripheral
part of the concave portion and fitted in the other of the outer
peripheral part of the convex portion and the inner peripheral part
of the concave portion; and a separating mechanism for moving at
least one of the female coupling member and the male coupling
member to be stopped in a position placed apart from the position
for the connecting state of the first connecting portion and the
second connecting portion by the predetermined distance within a
range in which the seal member is fitted in the other of the outer
peripheral part of the convex portion and the inner peripheral part
of the concave portion.
3. The electrostatic coating apparatus according to claim 1,
wherein the cleaning fluid is deionized water.
4. The electrostatic coating apparatus according to claim 1,
wherein the male coupling member further includes a guide portion
taking such a shape as to externally cover a part having the
concave portion formed thereon when the first connecting portion
and the second connecting portion are connected to each other.
5. A connecting device for a fluid passage comprising: a female
coupling member having a first connecting portion on one end side
thereof; a male coupling member having, on one end side thereof, a
second connecting portion to be connected to the first connecting
portion a passage formed in the female coupling member and a
passage formed in the male coupling member being connected to each
other through a connection of the first connecting portion and the
second connecting portion; a first operating mechanism for driving
at least one of the female coupling member and the male coupling
member to cause the first connecting portion and the second
connecting portion to approach each other; a second operating
mechanism for driving at least one of the female coupling member
and the male coupling member to separate the first connecting
portion and the second connecting portion from each other; and a
controller for controlling a thrust generated in each of the first
operating mechanism and the second operating mechanism, wherein one
of the female coupling member and the male coupling member includes
a supplying hole for supplying a cleaning fluid toward the first
connecting portion and the second connecting portion, and a
discharging hole for discharging the cleaning fluid from the first
connecting portion and the second connecting portion, wherein one
of the female coupling member and the male coupling member is
provided with a seal member for closely coming in contact with the
other coupling member, and wherein the controller controls the
thrust generated in the first operating mechanism to be greater
than a force acting in such a direction as to separate the first
connecting portion and the second connecting portion from each
other against the thrust generated in the first operating mechanism
in the supply of the cleaning fluid and to be equal to or smaller
than the thrust generated in the second operating mechanism in a
work for cleaning the first connecting portion and the second
connecting portion with the cleaning fluid, and separates the first
connecting portion and the second connecting portion from each
other within a range in which the seal member closely comes in
contact with the other coupling member.
6. The connecting device for a fluid passage according to claim 5,
wherein each of the first operating mechanism and the second
operating mechanism is constituted by an air cylinder for
generating a thrust through a supply of compressed air, and wherein
a cylinder diameter of the air cylinder of the second operating
mechanism is larger than that of the air cylinder of the first
operating mechanism.
7. The connecting device for a fluid passage according to claim 5,
wherein the cleaning fluid is deionized water.
8. An electrostatic coating apparatus for an electrically
conductive coating material which supplies the electrically
conductive coating material through a coating material supplying
path to a coating gun to which a high voltage is applied, the
apparatus comprising: an insulating mechanism provided in the
coating material supplying path for dividing the coating material
supplying path into an application side which is conducted to the
coating gun and a non-application side which is insulated from the
coating gun; a fluid supplying path which is grounded and conducted
to a part on the application side of the coating material supplying
path; and a fluid supplying device for supplying an electrically
conductive fluid to the fluid supplying path.
9. The electrostatic coating apparatus according to claim 8 further
comprising a controller for controlling the fluid supplying device,
the controller starting to supply the electrically conductive fluid
to the fluid supplying path after the application of the high
voltage to the coating gun is ended.
10. The electrostatic coating apparatus according to claim 8,
wherein the electrically conductive fluid is deionized water.
11. The electrostatic coating apparatus according to claim 8
further comprising a gas supplying device for supplying a gas to
the fluid supplying path.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electrostatic coating
apparatus in which a high voltage is applied to an electrically
conductive coating material so as to carry out coating.
BACKGROUND ART
[0002] Conventionally, as a coating apparatus for carrying out
coating over a body of a car, for example, an electrostatic coating
apparatus for an electrically conductive coating material is known.
In the electrostatic coating apparatus for an electrically
conductive coating material, a high voltage is applied to the
electrically conductive coating material supplied to a coating gun.
Therefore, it is necessary to prevent a current from leaking out of
a coating material supplying path for supplying the coating
material to the coating gun. For this reason, an insulating and
separating valve for temporarily dividing the coating material
supplying path to bring an electrical insulating state is provided
in the coating material supplying path (see Patent Documents 1 and
2). In other words, in electrostatic coating, the insulating and
separating valve electrically insulates and separates the coating
material supplying path into an application side in which a high
voltage is applied and the other non-application side.
Consequently, the current is prevented from leaking in the coating.
On the other hand, the coating material supplying path including
the insulating and separating valve is connected in the supply of
the coating material to the coating gun. Thus, the coating material
can be supplied.
[0003] In order to remove the coating material left in the
insulating and separating valve in a proper timing between the
supply of the coating material and the electrostatic coating,
moreover, a cleaning fluid is supplied to the insulating and
separating valve so that the insulating and separating valve is
cleaned. Then, an air blow is carried out over the insulating and
separating valve in order to dry the cleaning fluid.
[0004] In the conventional electrostatic coating apparatus,
however, it is necessary to carefully carry out the air blow
because there is a possibility that the cleaning fluid might be
left on the application side. The cleaning fluid left on the
application side might cause the leakage of the current in
subsequent coating. Under the circumstances, therefore, plenty of
time is required for the air blow.
[0005] When the coating material supplying path is to be cleaned
with the cleaning fluid, moreover, a discharge or a heat generation
is caused in a connecting part of the insulating and separating
valve if the insulating and separating valve is connected in a
state in which an electric charge is left on the application side.
Therefore, there is a possibility that the connecting part might be
broken, resulting in a reduction in a sealing force. For this
reason, it is necessary to remove the residual electric charge from
the application side of the coating material supplying path before
the insulating and separating valve is connected after the
electrostatic coating is carried out. In the conventional
electrostatic coating apparatus, however, waiting is carried out
until the residual electric charge is spontaneously discharged from
the application side. Therefore, it is impossible to rapidly start
the work for cleaning the coating material supplying path after
performing the electrostatic coating.
[0006] In the connecting device described in Patent Document 1,
moreover, the cleaning solution is supplied in the state in which
the insulating and separating valve is connected. For this reason,
there is a possibility that the cleaning solution cannot be
supplied to the part in which the member on one of the sides of the
insulating and separating valve and the member on the other side
come in contact with each other and the coating material might be
thus left.
[0007] On the other hand, in the connecting device described in
Patent Document 2, two cylinders for generating thrusts in opposite
directions to each other are used to form a clearance between the
member on one of the sides of the insulating and separating valve
and the member on the other side when the cleaning solution is to
be supplied. More specifically, a necessary clearance for the
cleaning is formed by causing both of the members to approach each
other through one of the cylinders and separating them from each
other through the other cylinder in the cleaning. In the connecting
device, however, a pressure of the cleaning solution to be supplied
to the clearance between both of the members is not considered in
detail. For this reason, when the cleaning solution is supplied,
the member is pushed back by the pressure of the cleaning solution
so that the cleaning solution leaks. As a result, there is a
possibility that a cleaning failure might be caused.
PRIOR ART DOCUMENT
Patent Document
[0008] Patent Document 1: JP-A-08-257443 [0009] Patent Document 2:
JP-A-2008-73578
SUMMARY OF INVENTION
[0010] One or more embodiments of the invention provide an
electrostatic coating apparatus capable of suppressing an
occurrence of a current leakage in coating of an electrostatically
conductive coating material, and furthermore, implementing a
simplification of an air blow over an insulating and separating
valve and a reduction in a time.
[0011] Moreover, one or more embodiments of the invention provide
an electrostatic coating apparatus capable of cleaning, without a
residual coating material, a part in which one of members of an
insulating and separating valve and the other member come in
contact with each other.
[0012] Furthermore, one or more embodiments of the invention
provide an electrostatic coating apparatus capable of applying a
high voltage to carry out electrostatic coating and then
discharging an electric charge left in a coating material supplying
path rapidly.
[0013] In accordance with one or more embodiments of the invention,
an electrostatic coating apparatus (for instance, an electrostatic
coating apparatus 1 according to a first exemplary embodiment) for
an electrically conductive coating material supplies the
electrically conductive coating material through a coating material
supplying path (for instance, a coating material supplying path 11)
to a coating gun (for instance, a coating gun 13) to which a high
voltage is applied, and is provided with an insulating and
separating valve (for instance, an insulating and separating valve
32) capable of electrically insulating and separating the coating
material supplying path into an application side in which the high
voltage is applied and the other non-application side. The
insulating and separating valve is provided with a female coupling
member (for instance, a female coupling member 32U) having a
concave portion (for instance, a concave portion 52) serving as one
of coupling portions and a first connecting portion (for instance,
a connecting portion 54) provided on a bottom face (for instance, a
bottom face 52a) of the concave portion and serving as a connecting
portion of the coating material supplying path, and a male coupling
member (for instance, a male coupling member 32D) having a convex
portion (for instance, a convex portion 62) serving as the other
coupling portion to be coupled to the concave portion and a second
connecting portion (for instance, a connecting portion 64) provided
on a tip of the convex portion and serving as a connecting portion
of a passage to be connected to the first connecting portion. One
of the female coupling member and the male coupling member is
provided on the non-application side and includes a supplying hole
(for instance, a cleaning fluid supplying hole 55a) for supplying a
cleaning fluid to the first connecting portion and the second
connecting portion when the first connecting portion and the second
connecting portion are disposed apart from a position for a
connecting state by a predetermined distance, and a discharging
hole (for instance, a cleaning fluid discharging hole 56a) for
discharging the cleaning fluid supplied to the first connecting
portion and the second connecting portion. One of the female
coupling member and the male coupling member is provided on the
application side.
[0014] According to the structure, the supplying hole for supplying
the cleaning fluid and the discharging hole for discharging the
cleaning fluid are provided in either the female coupling member or
the male coupling member which constitutes the insulating and
separating value and is disposed on the non-application side. As a
result, the path through which the cleaning fluid flows is formed
in the coupling member on the non-application side and is not
formed in the coupling member on the application side. For this
reason, even if an electrically conductive cleaning fluid is left
in the path on the non-application side, it is prevented from
entering the application side. Accordingly, there is no possibility
that a current might leak out of the coating gun. Furthermore, it
is not necessary to take the leakage of the current into
consideration. Consequently, it is sufficient to carry out such a
simple air blow as to pull the cleaning fluid out toward the
discharging side. As a result, it is also possible to reduce a time
taken for the air blow.
[0015] With the structure, the male coupling member or the female
coupling member may further include a seal member (for instance, a
seal member 65 or a seal member 201) to be fitted in an inner
peripheral surface of the concave portion in the female coupling
member or an outer peripheral surface of the convex portion in the
female coupling member in an outer peripheral part of the convex
portion or an inner peripheral part of the concave portion.
Moreover, it is also possible to further include a separating
mechanism (for instance, a separating mechanism constituted by a
movable member 18 and an air cylinder 19 or a separating mechanism
100) capable of moving at least one of the female coupling member
and the male coupling member to be stopped in a position placed
apart from a position for a connecting state of the first
connecting portion and the second connecting portion by the
predetermined distance (for instance, d=0.5 mm) within a range in
which the seal member is fitted in the inner peripheral surface or
the outer peripheral surface.
[0016] According to the structure, the seal member is provided in
the male coupling member, and the insulating and separating valve
can be cleaned in the state in which the first connecting portion
and the second connecting portion are separated from each other by
the certain distance within the range in which the seal member is
fitted in the inner peripheral surface of the concave portion in
the female coupling member. Consequently, it is possible to clean
whole connecting surfaces of the first connecting portion and the
second connecting portion. As a result, it is possible to suppress
an occurrence of poor quality due to a color mixture. Moreover, it
is also possible to prevent the electrically conductive coating
material which is left from sticking to the application side.
Therefore, there is no possibility that a current might leak out of
the coating gun.
[0017] With the structure, the cleaning fluid may be deionized
water.
[0018] If the deionized water is used for the cleaning fluid, it is
possible to carry out the cleaning work without leaving a hard
component such as calcium or magnesium.
[0019] With the structure, the male coupling member may further
include a guide portion (for instance, a guide portion 61a) taking
such a shape as to externally cover a part of the female coupling
member on which the concave portion is formed when the first
connecting portion and the second connecting portion are connected
to each other.
[0020] According to the structure, it is possible to aid a
maintenance of the coupling state of the female coupling member and
the male coupling member through the guide portion.
[0021] According to the structure, the path through which the
cleaning fluid for cleaning the insulating and separating valve
flows is formed on the non-application side in the insulating and
separating valve and is not formed on the application side. For
this reason, even if the electrically conductive cleaning fluid is
left in the path on the non-application side, it is prevented from
entering the application side. Accordingly, there is no possibility
that a current might leak out of the coating gun. Furthermore, it
is not necessary to take the leakage of the current into
consideration. Consequently, it is sufficient to carry out such a
simple air blow as to pull the cleaning fluid out toward the
discharging side. As a result, it is also possible to reduce a time
taken for the air blow.
[0022] Further, in accordance with one or more embodiments of the
invention, a connecting device (for instance, an insulating and
separating valve 2032) for a fluid passage (for instance, a coating
material supplying path 2022 according to a fifth exemplary
embodiment) is provided with a female coupling member (for
instance, a female coupling member 2032U or 2232U) having a first
connecting portion (for instance, a first connecting portion 2054)
on one end side thereof, and a male coupling member (for instance,
a male coupling member 2032D or 2232D) having, on one end side
thereof, a second connecting portion (for instance, a second
connecting portion 2064) to be connected to the first connecting
portion. Through the connection of the first connecting portion and
the second connecting portion, a passage (for instance, a first
coating material passage 2053) formed in the female coupling member
is connected to a passage (for instance, a second coating material
passage 2063) formed in the male coupling member. One of the female
coupling member and the male coupling member includes a supplying
hole (for instance, a cleaning fluid supplying hole 2055) for
supplying a cleaning fluid toward the first connecting portion and
the second connecting portion, and a discharging hole (for
instance, a cleaning fluid discharging hole 2056) for discharging
the cleaning fluid from the first connecting portion and the second
connecting portion. One of the female coupling member and the male
coupling member (for instance, the male coupling member 2032D) is
provided with a seal member (for instance, a seal member 2066 or
2266) for closely coming in contact with the other coupling member.
The connecting device includes a first operating mechanism (for
instance, a main cylinder 2111) for driving at least one of the
female coupling member and the male coupling member by a
predetermined thrust to cause the first connecting portion and the
second connecting portion to approach each other, a second
operating mechanism (for instance, a cylinder 2113 for a cleaning
position) for driving at least one of the female coupling member
and the male coupling member by a predetermined thrust to separate
the first connecting portion and the second connecting portion from
each other, and a controller (for instance, a controller 2500) for
controlling a thrust generated in each of the first operating
mechanism and the second operating mechanism. The controller
controls the thrust generated in the first operating mechanism to
be greater than a force acting in such a direction as to separate
the first connecting portion and the second connecting portion from
each other against the thrust generated in the first operating
mechanism in the supply of the cleaning fluid and to be equal to or
smaller than the thrust generated in the second operating mechanism
in a work for cleaning the first connecting portion and the second
connecting portion with the cleaning fluid, and separates the first
connecting portion and the second connecting portion from each
other within a range in which the seal member closely comes in
contact with the other coupling member.
[0023] According to the structure, in the case in which the passage
formed in the female coupling member and the passage formed in the
male coupling member are connected to form a single passage, the
thrust is generated in the first operating mechanism to connect the
first connecting portion and the second connecting portion to each
other. In the case in which the first connecting portion and the
second connecting portion are cleaned, moreover, the thrust is
generated in the second operating mechanism with the thrust
generated in the first operating mechanism. Thus, the first
connecting portion and the second connecting portion are separated
from each other within the range in which the seal member closely
comes in contact with the other coupling member. By supplying the
cleaning fluid from the supplying hole in this state, it is
possible to clean the first connecting portion and the second
connecting portion. Moreover, the cleaning fluid subjected to the
cleaning work is discharged from the discharging hole. According to
the structure, particularly, the thrust generated in the first
operating mechanism is controlled to be greater than the force
acting in such a direction as to separate the first connecting
portion and the second connecting portion from each other in the
supply of the cleaning fluid and to be equal to or smaller than the
thrust generated in the second operating mechanism. Even if the
supply of the cleaning fluid is started, consequently, it is
possible to properly maintain an interval between the first
connecting portion and the second connecting portion. Therefore, it
is possible to clean the first connecting portion and the second
connecting portion without a residue. In the case in which the
connecting device is applied to the coating material supplying path
of the electrostatic coating apparatus, moreover, it is possible to
clean the first and second connecting portions without a residual
coating material. Consequently, it is possible to prevent a leakage
of a current more reliably when charging the coating gun.
Accordingly, the coating material can be charged efficiently.
Therefore, it is possible to enhance a coating efficiency and
quality of a product.
[0024] With the structure, each of the first operating mechanism
and the second operating mechanism may include an air cylinder for
generating a thrust through a supply of compressed air. A cylinder
diameter of the second operating mechanism may be greater than that
of the first operating mechanism.
[0025] The air cylinder generates a thrust which is proportional to
a square of the cylinder diameter. Therefore, the air cylinders are
used as the first and second operating mechanisms and the cylinder
diameter of the second operating mechanism is set to be larger than
that of the first operating mechanism. Consequently, also in the
case in which the first and second operating mechanisms are
operated at an equal operating pressure, for instance, the thrust
generated in the second operating mechanism can be greater than the
thrust generated in the first operating mechanism. Accordingly, it
is possible to reliably form a clearance between the first
connecting portion and the second connecting portion, thereby
carrying out the cleaning work.
[0026] With the structure, the cleaning fluid may be deionized
water.
[0027] By using the ionized water in the cleaning work, it is
possible to carry out the cleaning work without leaving a hard
component such as calcium or magnesium.
[0028] Moreover, in accordance with one or more embodiments of the
invention, an electrostatic coating apparatus (for instance, an
electrostatic coating apparatus 3001) for an electrically
conductive coating material supplies the electrically conductive
coating material through a coating material supplying path (for
instance, a coating material supplying path 3022) to a coating gun
(for instance, a coating gun 3013) to which a high voltage is
applied, and includes an insulating mechanism (for instance, an
insulating and separating valve 3032) provided in the coating
material supplying path for dividing the coating material supplying
path into an application side which is conducted to the coating gun
and a non-application side which is insulated from the coating gun,
a fluid supplying path (for instance, a discharging fluid supplying
path 3042) which is grounded and conducted to a part on the
application side of the coating material supplying path, and a
fluid supplying device (for instance, a pump of a supplying device
3043) for supplying an electrically conductive fluid to the fluid
supplying path.
[0029] According to the structure, the coating material supplying
path is divided into the application side which is conducted to the
coating gun and in which the high voltage is applied and the
non-application side which is insulated from the coating gun
through the insulating mechanism. Furthermore, there are provided
the fluid supplying path which is conducted to a part on the
application side and is grounded and the fluid supplying device for
supplying the electrically conductive fluid to the fluid supplying
path. By applying the high voltage to the coating gun,
consequently, it is possible to rapidly discharge an electric
charge left on the application side of the coating material
supplying path through the electrically conductive fluid flowing in
the fluid supplying path.
[0030] With the structure, the electrically conductive fluid is
supplied to the separate fluid supplying path from the coating
material supplying path to discharge the residual electric charge.
In addition, it is also possible to suppose that the electrically
conductive fluid is supplied to the coating material supplying
path, thereby discharging the residual electric charge. In this
case, however, the electrically conductive fluid is caused to flow
to the coating material supplying path so that a leakage or a spark
might occur, resulting in a damage of the coating material
supplying path. When the coating material supplying path is
damaged, there is a possibility that a cleaning property of the
passage might be deteriorated. In the case in which the
electrically conductive fluid is caused to flow to the coating
material supplying path, moreover, it is necessary to use an
electrically conductive fluid which does not influence the coating
material on the assumption that the electrically conductive fluid
left in the passage might mix with the coating material. For
instance, in some cases in which alcohol mixes with a water-based
coating material, a condensation is caused. For this reason, the
alcohol cannot be used as the electrically conductive fluid.
[0031] On the other hand, with the structure, the coating material
supplying path is prevented from being damaged also in the case in
which the electrically conductive fluid is caused to flow to the
separate fluid supplying path from the coating material supplying
path, resulting in an occurrence of a leakage or a spark.
Therefore, it is possible to prevent the cleaning property of the
coating material supplying path from being deteriorated. Also in
the case in which the fluid supplying path is so damaged as to be
replaced, moreover, it is possible to replace the fluid supplying
path more inexpensively as compared with the case in which the
coating material supplying path is replaced. Furthermore, there is
no possibility that the electrically conductive fluid might mix
with the coating material. Consequently, it is possible to use more
fluids as the electrically conductive fluid.
[0032] With the structure, the electrostatic coating apparatus may
further include a controller for controlling the fluid supplying
apparatus, and the controller may start to supply the electrically
conductive fluid to the fluid supplying path after the application
of the high voltage to the coating gun is ended.
[0033] According to the structure, the supply of the electrically
conductive fluid to the fluid supplying path is started after the
application of the high voltage to the coating gun is ended.
Consequently, it is possible to rapidly discharge the electric
charge left on the application side of the coating material
supplying path after the electrostatic coating. Therefore, in the
case in which the insulating and separating valve is used as the
insulating mechanism, for instance, it is possible to reduce a time
taken for connecting the insulating and separating valve.
Accordingly, it is possible to rapidly start the work for cleaning
the coating material supplying path or the insulating and
separating valve after the electrostatic coating. Therefore, it is
possible to enhance a coating efficiency.
[0034] With the structure, the electrically conductive fluid may be
deionized water.
[0035] For instance, in the case in which clean water is used as
the electrically conductive fluid, there is a possibility that a
current might leak out of the application side of the coating
material supplying path through the fluid supplying path while the
clean water is not supplied due to the fact that impurity contained
in the clean water is left in the fluid supplying path. On the
other hand, according to the embodiments, the deionized water
having a smaller amount of impurity such as chlorine than the clean
water is used as the electrically conductive fluid. Consequently,
it is possible to reduce the amount of the impurity left in the
fluid supplying path. Therefore, it is possible to prevent the
current from leaking out of the coating material supplying path
while the electrically conductive fluid is not supplied.
[0036] With the structure, the electrostatic coating apparatus may
further include a gas supplying device (for instance, an air
compressor of a supplying device 3043 which will be described
below) for supplying a gas to the fluid supplying path.
[0037] According to the structure, there is provided the gas
supplying device for supplying a gas to the fluid supplying path.
For instance, consequently, it is possible to discharge the
electrically conductive fluid left in the fluid supplying path by
supplying the electrically conductive fluid to the fluid supplying
path to discharge a residual electric charge from the application
side of the coating material supplying path and then supplying a
gas to the fluid supplying path. Thus, it is possible to prevent
the current from leaking out of the application side of the coating
material supplying path through the fluid supplying path while the
electrically conductive fluid is not supplied.
[0038] Other aspects and advantages of the invention will be
apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0039] FIG. 1 is a typical view showing a schematic structure of an
electrostatic coating apparatus according to a first exemplary
embodiment.
[0040] FIG. 2 is a longitudinal sectional view showing a structure
of an insulating and separating valve in the electrostatic coating
apparatus according to the first exemplary embodiment.
[0041] FIG. 3 is a longitudinal sectional view showing the
structure of the insulating and separating valve in the
electrostatic coating apparatus according to the first exemplary
embodiment.
[0042] FIG. 4 is a longitudinal sectional view showing the
structure of the insulating and separating valve in the
electrostatic coating apparatus according to the first exemplary
embodiment.
[0043] FIG. 5 is a longitudinal sectional view showing the
structure of the insulating and separating valve in the
electrostatic coating apparatus according to the first exemplary
embodiment.
[0044] FIG. 6 is a longitudinal sectional view showing a schematic
structure of a periphery of a separating mechanism and an
insulating and separating valve in an electrostatic coating
apparatus according to a second exemplary embodiment.
[0045] FIG. 7 is a longitudinal sectional view showing the
schematic structure of the periphery of the separating mechanism
and the insulating and separating valve in the electrostatic
coating apparatus according to the second exemplary embodiment.
[0046] FIG. 8 is a longitudinal sectional view showing the
schematic structure of the periphery of the separating mechanism
and the insulating and separating valve in the electrostatic
coating apparatus according to the second exemplary embodiment.
[0047] FIG. 9 is a longitudinal sectional view showing a structure
of an insulating and separating valve in an electrostatic coating
apparatus according to a third exemplary embodiment.
[0048] FIG. 10 is a longitudinal sectional view showing a structure
of an insulating and separating valve in an electrostatic coating
apparatus according to a fourth exemplary embodiment.
[0049] FIG. 11 is a view showing a schematic structure of an
electrostatic coating apparatus according to a fifth exemplary
embodiment.
[0050] FIG. 12 is a longitudinal sectional view showing structures
of a female coupling member and a male coupling member in an
insulating and separating valve according to the fifth exemplary
embodiment.
[0051] FIG. 13 is a longitudinal sectional view showing a structure
of a separating mechanism in the insulating and separating valve
according to the fifth exemplary embodiment.
[0052] FIG. 14 is a view for explaining an operation of the
separating mechanism in the insulating and separating valve
according to the fifth exemplary embodiment.
[0053] FIG. 15 is a view for explaining an operation of the female
coupling member and the male coupling member in the insulating and
separating valve according to the fifth exemplary embodiment.
[0054] FIG. 16 is a view for explaining the operation of the
separating mechanism in the insulating and separating valve
according to the fifth exemplary embodiment.
[0055] FIG. 17 is a longitudinal sectional view showing structures
of a female coupling member and a male coupling member in an
insulating and separating valve according to a variant of the fifth
exemplary embodiment.
[0056] FIG. 18 is a view showing a schematic structure of an
electrostatic coating apparatus according to a sixth exemplary
embodiment.
[0057] FIG. 19 is a sectional view showing a structure of a joint
portion in a high speed grounding device according to the sixth
exemplary embodiment.
[0058] FIG. 20 is a chart showing a time variation in a voltage
value of a coating material supplying path after an end of an
application of a high voltage.
DESCRIPTION OF EMBODIMENTS
[0059] Exemplary embodiments according to the invention will be
described below with reference to the drawings.
First Exemplary Embodiment
[0060] FIG. 1 is a typical view showing a schematic structure of an
electrostatic coating apparatus 1 according to a first embodiment
of the invention. The electrostatic coating apparatus 1 serves to
carry out electrostatic coating over an object to be coated. It is
possible to employ, as the object to be coated, a body of a car,
for instance.
[0061] The electrostatic coating apparatus 1 includes a coating
material supplying path 11, an intermediate reservoir 12, a bell
type coating gun 13, a ram 14, a servomotor 15, a trigger valve 16,
a dump valve 17, a movable member 18, an air cylinder 19, a
cleaning fluid supply switching valve 20, and a cleaning fluid
discharge switching valve 21.
[0062] A color change valve CV includes valves CV1 and CV2. A valve
SV1 linked to the valve CV1 controls a supply of air (A) and a
cleaning fluid (W) which are to be used in a color change. The
valve CV1 controls a supply of the air or the cleaning fluid from
the valve SV1. The valve CV2 is connected to a plurality of coating
material tanks (not shown) respectively and controls a supply of an
electrically conductive coating material (hereinafter referred to
as a coating material) from a fuel tank which is connected. In
response to a control signal sent from a controller which is not
shown, each of the valves SV1, CV1 and CV2 is controlled to be
opened/closed and the coating material, the air or the cleaning
fluid which is intended is compression transported to the coating
material supplying path 11.
[0063] For instance, the coating material stored in a predetermined
coating material tank is compression transported to the coating
material supplying path 11 through the color change valve CV.
Furthermore, the coating material is compression transported to the
intermediate reservoir 12 through the coating material supplying
path 11 and is stored therein. The coating material stored in the
intermediate reservoir 12 is supplied to a tip of the coating gun
13 through the trigger valve 16. The coating gun 13 sprays the
coating material from the tip. In detail, the coating material is
supplied to the coating gun 13 in a state in which a high voltage
is applied. Consequently, the electrostatic coating apparatus 1 can
carry out electrostatic coating by charging and atomizing the
coating material and spraying the coating material from the tip of
the coating gun 13. The coating gun 13 is fixed to the ram 14 which
can be reciprocated vertically and transversely. By reciprocating
the ram 14 vertically and transversely depending on a shape of an
object to be coated, accordingly, it is possible to maintain an
almost constant clearance between the tip of the coating gun 13 and
the object to be coated.
[0064] The coating material supplying path 11 is provided with a
coating material hose 31, an insulating and separating valve 32,
and a coating material hose 33. The insulating and separating valve
32 includes a female coupling member 32U fixed to the movable
member 18 and a male coupling member 32D fixed to the coating gun
13. The movable member 18 is vertically moved by means of the air
cylinder 19 fixed to the ram 14. When the movable member 18 is
moved downward, accordingly, the female coupling member 32U is
bonded to the male coupling member 32D. When the movable member 18
is moved upward, moreover, the female coupling member 32U is
separated from the male coupling member 32D.
[0065] The servomotor 15 precisely controls a position of a piston
41 provided on the intermediate reservoir 12. When the piston 41 is
moved forward by the control of the servomotor 15, that is, is
moved in such a direction as to approach the tip of the coating gun
13 in FIG. 1, the coating material stored in the intermediate
reservoir 12 is compression transported to the coating gun 13
through the trigger valve 16. When the piston 41 is moved backward
by the control of the servomotor 15, that is, is moved in such a
direction as to separate from the tip of the coating gun 13 in FIG.
1, furthermore, the coating material is sucked from the insulating
and separating valve 32 through the coating material hose 33 and is
thus stored in the intermediate reservoir 12.
[0066] The trigger valve 16 controls the supply of the coating
material from the intermediate reservoir 12 to the coating gun 13.
The dump valve 17 controls a discharge of a waste liquid of the
coating material in the color change. A cleaning valve SV3 controls
the supply of the air (A) and the cleaning fluid (W) which are to
be used in cleaning of the coating gun 13. Each of the trigger
valve 16, the dump valve 17 and the cleaning valve SV3 is
controlled to be opened/closed in response to a control signal sent
from the controller which is not shown.
[0067] A cleaning valve SV2 controls the supply of the air (A) and
the cleaning fluid (W) which are to be used in cleaning of the
insulating and separating valve 32. The cleaning fluid supply
switching valve 20 controls the supply of the air or the cleaning
fluid from the cleaning valve SV2 to the female coupling member
32U. The cleaning fluid discharge switching valve 21 controls the
discharge of the air or the cleaning fluid from the female coupling
member 32U. Each of the cleaning valve SV2, the cleaning fluid
supply switching valve 20 and the cleaning fluid discharge
switching valve 21 is controlled to be opened/closed in response to
a control signal sent from the controller which is not shown.
Consequently, the cleaning fluid or the air is transmitted in order
of the cleaning valve SV2, the cleaning fluid supply switching
valve 20, the female coupling member 32U of the insulating and
separating valve 32 and the cleaning fluid discharge switching
valve 21.
[0068] FIG. 2 is a longitudinal sectional view showing a structure
of the insulating and separating valve 32 in the electrostatic
coating apparatus 1. Referring to each member constituting the
insulating and separating valve 32, an end on a side where the
female coupling member 32U and the male coupling member 32D are
coupled to each other will be referred to as a tip, and an end on
an opposite side thereto will be referred to as a base end.
[0069] The female coupling member 32U of the insulating and
separating valve 32 includes a valve body 51, a concave portion 52,
a coating material supplying passage 53, a connecting portion 54, a
cleaning fluid supplying member 55, and a cleaning fluid
discharging member 56.
[0070] The concave portion 52 is provided on a tip of the valve
body 51 fixed to the movable member 18 (FIG. 1). The concave
portion 52 functions as a coupling portion to be coupled to a
convex portion 62 of the male coupling member 32D. The coating
material supplying passage 53 is formed to penetrate from a central
inner part of the valve body 51 to a bottom face 52a of the concave
portion 52. The connecting portion 54 provided on the bottom face
52a of the concave portion 52 is engaged with a connecting portion
64 of the male coupling member 32D when the concave portion 52 and
the convex portion 62 are coupled to each other. As a result, the
coating material supplying passage 53 is connected to a coating
material supplying passage 63 of the male coupling member 32D. The
cleaning fluid supplying member 55 is provided on a right side
surface of FIG. 2 in the valve body 51. A cleaning fluid supplying
hole 55a is formed to penetrate from a central inner part of the
cleaning fluid supplying member 55 to the bottom face 52a of the
concave portion 52. Moreover, the cleaning fluid discharging member
56 is provided on a left side surface of FIG. 2 in the valve body
51. A cleaning fluid discharging hole 56a is formed to penetrate
from a central inner part of the cleaning fluid discharging member
56 to the bottom face 52a of the concave portion 52. Accordingly,
the air or the cleaning fluid which is sent from the cleaning fluid
supply switching valve 20 (FIG. 1) is supplied to the insulating
and separating valve 32 through the cleaning fluid supplying hole
55a. Furthermore, the supplied air or cleaning fluid is discharged
to the cleaning fluid discharge switching valve 21 (FIG. 1) through
the cleaning fluid discharging hole 56a.
[0071] On the other hand, the male coupling member 32D of the
insulating and separating valve 32 includes a valve body 61, the
convex portion 62, the coating material supplying passage 63, the
connecting portion 64 and a seal member 65.
[0072] The convex portion 62 is provided on a tip of the valve body
61 fixed to the coating gun 13 (FIG. 1). The convex portion 62
functions as a coupling portion to be coupled to the concave
portion 52 of the female coupling member 32U. The coating material
supplying passage 63 is formed to penetrate from a central inner
part of the valve body 61 to an upper surface 62a of the convex
portion 62. A region of the upper surface 62a of the convex portion
62 which is engaged with the connecting portion 54 of the female
coupling member 32U in the coupling of the concave portion 52 to
the convex portion 62 is provided as the connecting portion 64.
Although the connecting portion 64 is thus formed as a partial
region of the upper surface 62a of the convex portion 62 in the
embodiment, it is also possible to constitute the connecting
portion 64 by a member which is independent of the convex portion
62. The connecting portion 64 is engaged with the connecting
portion 54 of the female coupling member 32U to connect the coating
material supplying passage 63 to the coating material supplying
passage 53 of the female coupling member 32U. The seal member 65 is
provided on an outer peripheral part of the convex portion 62 in
such a manner that it is fitted in an inner peripheral surface of
the concave portion 52 with the connecting portions 54 and 64
separated from each other by a certain distance.
[0073] A guide portion 61a formed on a tip of the valve body 61
takes such a shape as to externally cover a part in which the
concave portion 52 is formed when the concave portion 52 and the
convex portion 62 are coupled to each other, that is, the
connecting portions 54 and 64 are connected to each other.
Consequently, it is possible to aid a maintenance of the coupling
state of the female coupling member 32U and the male coupling
member 32D.
[0074] Next, an operation of the electrostatic coating apparatus 1
according to the first exemplary embodiment will be described. In
particular, an operation around the insulating and separating valve
32 will be described with reference to FIGS. 2 to 5. FIGS. 3 to 5
are longitudinal sectional views showing a structure of the
insulating and separating valve 32 in the electrostatic coating
apparatus 1 in the same manner as FIG. 2. In FIGS. 2 to 5, the
female coupling member 32U is disposed in different positions from
each other. The reason is that FIGS. 2 to 5 show a state in which
the female coupling member 32U gradually approaches the male
coupling member 32D in order.
[0075] Prior to the electrostatic coating, first of all, the
coating material is supplied to the intermediate reservoir 12 and
is stored therein. More specifically, when the movable member 18 is
moved downward by means of the air cylinder 19, the female coupling
member 32U of the insulating and separating valve 32 is moved
downward to approach the male coupling member 32D as shown in order
of FIGS. 2 to 4. As shown in FIG. 5, finally, the female coupling
member 32U is bonded to the male coupling member 32D. In other
words, the concave portion 52 of the female coupling member 32U is
coupled to the convex portion 62 of the male coupling member 32D.
As a result, the connecting portion 54 of the female coupling
member 32U is engaged with the connecting portion 64 of the male
coupling member 32D. Consequently, the coating material supplying
passage 53 of the female coupling member 32U is connected to the
coating material supplying passage 63 of the male coupling member
32D. In other words, there is connected the coating material
supplying path 11 for a linkage from the color change valve CV to
the intermediate reservoir 12. When an intended coating material is
selected by the color change valve CV in this state, the coating
material thus selected is compression transported to the
intermediate reservoir 12 via the coating material hose 31, the
insulating and separating valve 32 and the coating material hose
33, and is stored therein.
[0076] When the coating material is stored in a predetermined
amount in the intermediate reservoir 12, the movable member 18 is
moved upward by means of the air cylinder 19 so that the female
coupling member 32U of the insulating and separating valve 32 is
moved upward until the state of FIG. 4 is brought. The state of
FIG. 4 represents that the connecting portion 54 of the female
coupling member 32U and the connecting portion 64 of the male
coupling member 32D are separated from each other by a
predetermined distance (for instance, 0.5 mm) within a range in
which the seal member 65 of the male coupling member 32D is fitted
in the inner peripheral surface of the concave portion 52 in the
female coupling member 32U.
[0077] In the state of FIG. 4, the coating material is left in a
space surrounded by the concave portion 52 of the female coupling
member 32U and the convex portion 62 of the male coupling member
32D (which will be hereinafter referred to as a cleaning space) in
some cases. In order to remove the coating material, therefore, an
inner part of the cleaning space is cleaned in the following
manner. In other words, the cleaning fluid (W) is supplied from the
cleaning valve SV2 to the female coupling member 32U of the
insulating and separating valve 32 through the cleaning fluid
supply switching valve 20. The cleaning fluid is supplied to the
cleaning space through the cleaning fluid supplying hole 55a and is
utilized for cleaning the inner part of the cleaning space. In the
exemplary embodiment, thus, the cleaning work is carried out with
the connecting portion 54 of the female coupling member 32U and the
connecting portion 64 of the male coupling member 32D separated
from each other by a predetermined distance (for instance, 0.5 mm).
Therefore, the connecting portions 54 and 64 can be cleaned wholly.
As a result, the coating material is also removed almost wholly.
Even if a color change is then carried out, therefore, it is
possible to prevent low quality from being caused by a color
mixture. The cleaning fluid used in the cleaning work is discharged
to the cleaning fluid discharge switching valve 21 through the
cleaning fluid discharging hole 56a of the female coupling member
32U together with the coating material left in the cleaning
space.
[0078] A type of the cleaning fluid for cleaning the insulating and
separating valve 32 is not particularly restricted. In the
exemplary embodiment, for instance, deionized water is employed for
the cleaning fluid. It is possible to carry out the cleaning work
without causing a hard component such as calcium or magnesium to be
left. Thus, a sealing property of the seal member 65 can be
maintained. To the contrary, hard water is not suitable for the
cleaning fluid because the hard component is apt to be left after
drying so that there is a fear that the sealing property might be
deteriorated.
[0079] When the insulating and separating valve 32 is completely
cleaned, an air blow is carried out to dry the cleaning fluid. In
other words, in the state of FIG. 4, the air (A) is supplied from
the cleaning valve SV2 to the female coupling member 32U of the
insulating and separating valve 32 through the cleaning fluid
supply switching valve 20. The air is supplied into the cleaning
space through the cleaning fluid supplying hole 55a and is
discharged to the cleaning fluid discharge switching valve 21
through the cleaning fluid discharging hole 56a of the female
coupling member 32U.
[0080] When the air blow is ended, the insulating and separating
valve 32 electrically insulates and separates the coating material
supplying path 11 into the application side and the non-application
side as a pretreatment for the electrostatic coating. More
specifically, when the movable member 18 is moved upward by means
of the air cylinder 19, the female coupling member 32U of the
insulating and separating valve 32 is upward moved apart from the
male coupling member 32D as shown in order of FIGS. 4, 3 and 2. As
shown in FIG. 2, finally, the female coupling member 32U and the
male coupling member 32D are held with the connecting portion 54 of
the female coupling member 32U and the connecting portion 64 of the
male coupling member 32D separated from each other by a certain
distance (for instance, 180 mm or more). Consequently, an
electrical insulation can be maintained.
[0081] In a state in which the electrical insulation is thus
maintained, the electrostatic coating is carried out. In other
words, a voltage of a power supply is raised so that a high voltage
is applied to the coating gun 13. Then, the coating material is
supplied from the intermediate reservoir 12 to the tip of the
coating gun 13 through the trigger valve 16. Consequently, the
coating material is charged by the application of the high voltage
and is thus sprayed from the tip of the coating gun 13. Thus, the
electrostatic coating is carried out.
[0082] The high voltage is applied to the male coupling member 32D
of the insulating and separating valve 32 and is not applied to the
female coupling member 32U maintaining the electrical insulation
while the electrostatic coating is carried out. In other words, in
the exemplary embodiment, the male coupling member 32D is provided
on the application side and the female coupling member 32U is
provided on the non-application side. A path through which the
cleaning fluid flows (which will be hereinafter referred to as a
cleaning path) is formed in the female coupling member 32U on the
non-application side and is not formed in the male coupling member
32D on the application side as described above. For this reason,
even if an electrically conductive cleaning fluid is left in the
cleaning path on the non-application side, it does not enter the
application side. Accordingly, there is no possibility that a
current might leak out of the coating gun 13. In the embodiment,
thus, it is not necessary to take the leakage of the current into
consideration. Therefore, it is sufficient to carry out such a
simple air blow as to push the cleaning fluid out toward the
discharging side (the cleaning fluid discharge switching valve 21
side in the example of FIG. 1). As a result, a time taken for the
air blow is reduced. The air blow to push the cleaning fluid out
toward the discharging side is required for the following reason.
More specifically, if such push-out is not carried out, there is a
possibility that the cleaning fluid might be brought back to stick
to the male coupling member 32D on the application side when the
female coupling member 32U is separated from the male coupling
member 32D in order to perform an electrical insulation. In other
words, when the electrostatic coating is carried out in this state,
there is a possibility that a current might leak due to the
cleaning fluid sticking to the male coupling member 32D.
[0083] The electrostatic coating apparatus 1 according to the first
exemplary embodiment has been described as the electrostatic
coating apparatus to which the invention is applied. However, the
invention is not restricted to the first exemplary embodiment but
various embodiments can be employed.
[0084] For instance, in the first exemplary embodiment, the
separating mechanism including the movable member 18 and the air
cylinder 19 is employed as the separating mechanism for separating
the female coupling member 32U and the male coupling member 32D in
the insulating and separating valve 32 from each other. However,
the structure of the separating mechanism is not particularly
restricted to the structure according to the first exemplary
embodiment but it is sufficient to employ a structure in which the
female coupling member 32U and the male coupling member 32D are
held in the following first to third positions, respectively. The
first position is taken when the coating material is supplied to
the intermediate reservoir 12. In the first position, the convex
portion 62 of the male coupling member 32D is coupled to the
concave portion 52 of the female coupling member 32U. The first
position will be hereinafter referred to as a coupling position.
For instance, in the first exemplary embodiment, FIG. 5 shows a
state in which the female coupling member 32U and the male coupling
member 32D are held in the coupling position. The second position
is taken when the insulating and separating valve 32 is cleaned. In
the second position, the connecting portion 54 of the female
coupling member 32U is separated from the connecting portion 64 of
the male coupling member 32D by a predetermined distance (for
instance, 0.05 mm) in a state in which the seal member 65 of the
male coupling member 32D is fitted in the inner peripheral surface
of the concave portion 52 in the female coupling member 32U. The
second position will be hereinafter referred to as a cleaning
position. For instance, in the first exemplary embodiment, FIG. 4
shows a state in which the female coupling member 32U and the male
coupling member 32D are held in the cleaning position. The third
position is taken when the electrostatic coating is carried out. In
the third position, a distance between the connecting portion 54 of
the female coupling member 32U and the connecting portion 64 of the
male coupling member 32D is set to be a predetermined distance (for
instance, 180 mm or more) at which an electrical insulation can be
held with a high voltage applied to the coating gun 13. The third
position will be hereinafter referred to as a separating position.
For instance, in the first exemplary embodiment, FIG. 2 shows a
state in which the female coupling member 32U and the male coupling
member 32D are held in the separating position.
Second Exemplary Embodiment
[0085] An embodiment including a different separating mechanism
from that of the first exemplary embodiment will be described below
as a second exemplary embodiment according to the invention. FIGS.
6 to 8 are longitudinal sectional views showing a schematic
structure of a periphery of a separating mechanism 100 and an
insulating and separating valve 32 in an electrostatic coating
apparatus according to the second exemplary embodiment of the
invention. FIG. 6 shows a state in which a female coupling member
32U and a male coupling member 32D in the insulating and separating
valve 32 are held in a separating position. FIG. 7 shows a state in
which the female coupling member 32U and the male coupling member
32D are held in a cleaning position. FIG. 8 shows a state in which
the female coupling member 32U and the male coupling member 32D are
held in a coupling position.
[0086] In FIGS. 6 to 8, corresponding portions to those in FIGS. 1
to 5 have the same reference numerals and their description will be
properly omitted. A direction of a viewpoint in FIGS. 6 to 8 is
different from that in FIGS. 2 to 5. For this reason, a cleaning
fluid supplying member 55 and a cleaning fluid discharging member
56 are not shown in FIGS. 6 to 8. The female coupling member 32U
according to the second embodiment is also provided with the
cleaning fluid supplying member 55 and the cleaning fluid
discharging member 56 respectively in the same manner as in the
first exemplary embodiment.
[0087] The separating mechanism 100 includes a main cylinder 111, a
main rod 112, a cylinder 113 for a cleaning position, a rod 114 for
a cleaning position, a movable housing 115, and a stopper 116. The
main cylinder 111 is provided in the movable housing 115 in a
vertical direction. The main rod 112 is stored in the main cylinder
111 to be longitudinally movable. A backward moving direction of
the main rod 112 (a direction of storage in the main cylinder 111)
is set to be an upward direction. The cylinder 113 for a cleaning
position is provided above the main cylinder 111 in the movable
housing 115. The rod 114 for a cleaning position is stored in the
cylinder 113 for a cleaning position so as to be longitudinally
movable. A backward moving direction of the rod 114 for a cleaning
position (a direction of storage in the cylinder 113 for a cleaning
position) is set to be a downward direction. The main rod 112 and
the insulating and separating valve 32 are fixed to a bottom part
of the movable housing 115 respectively in such a manner that they
are opposed to each other. Interlockingly with a longitudinal
moving operation of the main rod 112 through the main cylinder 111,
accordingly, the movable housing 115 and the female coupling member
32U are also moved vertically. The stopper 116 is disposed opposite
to the rod 114 for a cleaning position in an upper part of the
movable housing 115. The stopper 116 controls a downward movement
of the movable housing 115 when it is engaged with the rod 114 for
a cleaning position. In other words, when the rod 114 for a
cleaning position is moved forward (upward) by the cylinder 113 for
a cleaning position in a state in which the stopper 116 is engaged
with the rod 114 for a cleaning position, the stopper 116 is upward
moved interlockingly therewith. As a result, the movable housing
115 is also moved upward.
[0088] Since the other structures of the electrostatic coating
apparatus according to the second exemplary embodiment are
basically the same as the structure of the electrostatic coating
apparatus 1 according to the first exemplary embodiment in FIG. 1,
illustration is omitted. Therefore, the description will be
omitted.
[0089] Next, an operation of the electrostatic coating apparatus
according to the second exemplary embodiment will be described.
Referring to the operation of the electrostatic coating apparatus
according to the second exemplary embodiment, only operations of
the insulating and separating valve 32 and the separating mechanism
100 are different and the other operations are coincident as
compared with the operation of the electrostatic coating apparatus
1 according to the first exemplary embodiment. Therefore, only the
operations of the insulating and separating valve 32 and the
separating mechanism 100 will be described below.
[0090] First of all, in the case in which a coating material is
supplied to an intermediate reservoir 12 and is stored therein, the
main rod 112 is moved forward (downward) by means of the main
cylinder 111 so that the movable housing 115 and the female
coupling member 32U are correspondingly moved downward to approach
the male coupling member 32D. At this time, the rod 114 for a
cleaning position is stored in the cylinder 113 for a cleaning
position so as not to come in contact with the stopper 116.
Finally, a concave portion 52 of the female coupling member 32U and
a convex portion 62 of the male coupling member 32D are coupled to
each other so that the downward movement of the movable housing 115
and the female coupling member 32U is stopped. Consequently, the
female coupling member 32U and the male coupling member 32D are
held in the coupling position as shown in FIG. 8.
[0091] When the coating material is stored in a predetermined
amount in the intermediate reservoir 12, then, the rod 114 for a
cleaning position is moved forward (upward) by means of the
cylinder 113 for a cleaning position. When the rod 114 for a
cleaning position is moved forward (upward) to some degree, the
stopper 116 is engaged with the rod 114 for a cleaning position.
When the rod 114 for a cleaning position is subsequently moved
forward (upward), accordingly, the movable housing 115 to which the
stopper 116 is fixed and the female coupling member 32U are
interlockingly moved upward. When the rod 114 for a cleaning
position is then moved forward (upward) to a stroke end and is
stopped, the movable housing 115 and the female coupling member 32U
are also stopped.
[0092] It is assumed that a position of installation of the
cylinder 113 for a cleaning position and the stroke end of the rod
114 for a cleaning position are regulated in such a manner that a
connecting portion 54 of the female coupling member 32U and a
connecting portion 64 of the male coupling member 32D are separated
from each other by a predetermined distance d (for instance, d=0.5
mm) in the case in which the rod 114 for a cleaning position is
moved forward (upward) to the stroke end and is then stopped. When
the regulation is carried out, the insulating and separating valve
32 can be cleaned with the female coupling member 32U and the male
coupling member 32D held in a position in which the connecting
portion 54 of the female coupling member 32U and the connecting
portion 64 of the male coupling member 32D are separated from each
other by the predetermined distance d (for instance, d=0.5 mm),
that is, the cleaning position as shown in FIG. 7. In the same
manner as the case according to the first exemplary embodiment,
consequently, the connecting portion 54 of the female coupling
member 32U and the connecting portion 64 of the male coupling
member 32D can be cleaned wholly. As a result, the residual coating
material is eliminated almost entirely. Even if a color change is
then carried out, therefore, it is possible to prevent poor quality
from being caused by a color mixture. In the second exemplary
embodiment, furthermore, the cylinder 113 for a cleaning position
and the rod 114 for a cleaning position are used in addition to the
main cylinder 111 and the main rod 112. Consequently, it is
possible to further reliably hold, in the cleaning position, a
position in which the female coupling member 32U and the male
coupling member 32D are disposed during the cleaning work.
[0093] When the work for cleaning the insulating and separating
valve 32 is completed and a subsequent air blow is also terminated,
the main rod 112 is moved backward (upward) by means of the main
cylinder 111 so that the movable housing 115 and the female
coupling member 32U are upward moved apart from the male coupling
member 32D. When the main rod 112 is moved backward (upward) to the
end and is thus stopped, finally, the upward movement of the
movable housing 115 and the female coupling member 32U is also
stopped. As shown in FIG. 6, consequently, the female coupling
member 32U and the male coupling member 32D are held in the
separating position. In other words, the connecting portion 54 of
the female coupling member 32U and the connecting portion 64 of the
male coupling member 32D are held apart from each other by a
certain distance D (for instance, D=180 mm or more). Consequently,
an electrical insulation can be maintained. In the same manner as
in the first exemplary embodiment, thereafter, electrostatic
coating is carried out with the electrical insulation
maintained.
Third Exemplary Embodiment
[0094] Next, an embodiment including a different insulating and
separating valve from that in each of the first and second
exemplary embodiments will be described as a third exemplary
embodiment according to the invention.
[0095] FIG. 9 is a longitudinal sectional view showing a structure
of an insulating and separating valve 32 in an electrostatic
coating apparatus 1 according to the third exemplary
embodiment.
[0096] In a comparison between FIGS. 2 and 9, the female coupling
member 32U is disposed in the upper part and the male coupling
member 32D is disposed in the lower part in the insulating and
separating valve 32 according to the first exemplary embodiment of
FIG. 2. On the other hand, a female coupling member 32U and a male
coupling member 32D are disposed in lower and upper parts in the
insulating and separating valve 32 according to the third exemplary
embodiment of FIG. 9, respectively. Since the other structures and
operations of the electrostatic coating apparatus 1 according to
the third exemplary embodiment are the same as those of the
electrostatic coating apparatus 1 according to the first exemplary
embodiment, their description will be omitted.
[0097] Thus, the female coupling member 32U is disposed below the
male coupling member 32D. Therefore, a cleaning fluid can be
prevented from dropping from a cleaning fluid supplying hole 55a or
a cleaning fluid discharging hole 56a into the male coupling member
32D on an application side. Accordingly, it is possible to further
suppress a fear that a current might leak out of a coating gun
13.
[0098] Moreover, the cleaning fluid supplying hole 55a and the
cleaning fluid discharging hole 56a are provided with a tilt in a
direction of a gravity. Therefore, the cleaning fluid left in the
cleaning fluid supplying hole 55a and the cleaning fluid
discharging hole 56a flows with the tilt in the direction of a
gravity. Consequently, it is possible to prevent the cleaning fluid
from dropping into the male coupling member 32D on the application
side. Accordingly, it is possible to further suppress the fear that
the current might leak out of the coating gun 13.
Fourth Exemplary Embodiment
[0099] FIG. 10 is a longitudinal sectional view showing a structure
of an insulating and separating valve 32 in an electrostatic
coating apparatus 1 according to a fourth embodiment.
[0100] In a comparison between FIGS. 2 and 10, the male coupling
member 32D includes the seal member 65 in the insulating and
separating valve 32 according to the first exemplary embodiment of
FIG. 2. On the other hand, a seal member 201 is provided in a
female coupling member 32U in the insulating and separating valve
32 according to the fourth exemplary embodiment of FIG. 10. In
other words, the seal member 201 is provided in an inner peripheral
part of a concave portion 52 in such a manner that it is fitted in
an outer peripheral surface of a convex portion 62 with connecting
portions 54 and 64 separated from each other by a certain distance.
Since the other structures and operations of the electrostatic
coating apparatus 1 according to the fourth exemplary embodiment
are the same as those in the electrostatic coating apparatus 1
according to the first exemplary embodiment, their description will
be omitted.
[0101] According to the first to fourth exemplary embodiments, the
following advantages can be obtained.
[0102] (1) In the prior art described in the Patent Document 1, the
cleaning path for the insulating and separating valve is also
formed in the coupling member (the lower valve) on the application
side. For this reason, there is a possibility that an electrically
conductive cleaning fluid might be left in the coupling member on
the application side, resulting in a leakage of a current during
electrostatic coating. In the case in which a cleaning fluid
containing, as a component, amine (for instance,
dimethylethylamine) to be generally used in a water-based coating
material is utilized, particularly, the amine is deposited on a
hose or a wall surface. For this reason, a probability of
occurrence of a current leakage is increased further greatly. In
order to reduce the probability of occurrence of the current
leakage, therefore, it is necessary to carefully carry out an air
blow after cleaning. In the case in which a cleaning retardant
coating material (for instance, aqueous primer) is utilized,
particularly, a great deal of time is also required for the air
blow in addition to the cleaning work. On the other hand, in the
first to fourth exemplary embodiments, the cleaning fluid supplying
hole 55a and the cleaning fluid discharging hole 56a are provided
in the female coupling member 32U on the non-application side in
the insulating and separating valve 32. As a result, the cleaning
path is formed in the female coupling member 32U on the
non-application side and is not formed in the male coupling member
32D on the application side. Even if the electrically conductive
cleaning fluid is left in the cleaning path on the non-application
side, therefore, it does not enter the application side.
Accordingly, there is no possibility that a current might leak out
of the coating gun 13. Furthermore, it is not necessary to take the
leakage of the current into consideration. Therefore, it is
sufficient to carry out such a simple air blow as to push the
cleaning fluid out toward the discharging side. As a result, a time
taken for the air blow can also be reduced.
[0103] (2) In the prior art described in the Patent Document 1, the
insulating and separating valve is cleaned in the state in which
the coupling member on the application side (the lower valve) and
the coupling member on the non-application side (the upper valve)
are bonded to each other. For this reason, the bonding surfaces of
both of the coupling members cannot be cleaned or can be cleaned
insufficiently. As a result, the coating material cannot be removed
sufficiently and there is a possibility that poor quality might be
caused by a color mixture when a color change is then carried out.
Moreover, there is also a possibility that a current might leak in
electrostatic coating when a residual coating material sticks to
the coupling member on the application side. On the other hand, in
the first to third exemplary embodiments, the seal member 65 is
provided in the male coupling member 32D, and the insulating and
separating valve 32 can be cleaned with the convex portion 62 and
the concave portion 52 separated from each other within the range
in which the seal member 65 is fitted in the inner peripheral
surface of the concave portion 52 in the female coupling member
32U. In the fourth exemplary embodiment, furthermore, the seal
member 201 is provided in the female coupling member 32U, and the
insulating and separating valve 32 can be cleaned with the convex
portion 62 and the concave portion 52 separated from each other
within the range in which the seal member 201 is fitted in the
outer peripheral surface of the convex portion 62 in the male
coupling member 32D. In other words, the insulating and separating
valve 32 can be cleaned in the state in which the female coupling
member 32U and the male coupling member 32D are held in the
cleaning position. Consequently, it is possible to wholly clean the
connecting portion 54 of the female coupling member 32U and the
connecting portion 64 of the male coupling member 32D (which
correspond to the whole bonding surfaces in the related art). As a
result, it is possible to prevent poor quality from being caused by
a color mixture. Moreover, the residual coating material is
eliminated almost entirely. Therefore, the coating material is
prevented from sticking to the application side. Consequently,
there is no possibility that a current might leak out of the
coating gun 13.
[0104] (3) In the first to fourth exemplary embodiments, it is
possible to employ deionized water as the cleaning fluid for the
insulating and separating valve 32. Consequently, it is possible to
carry out the cleaning work without leaving a hard component such
as calcium or magnesium.
[0105] (4) In the first to fourth exemplary embodiments, the guide
portion 61a is formed on the valve body 61 of the male coupling
member 32D. The guide portion 61a takes such a shape as to
externally cover the portion in which the concave portion 52 is
formed when the concave portion 52 is coupled to the convex portion
62, that is, the connecting portion 54 of the female coupling
member 32U is connected to the connecting portion 64 of the male
coupling member 32D. Accordingly, it is possible to aid the
maintenance of the coupling state of the female coupling member 32U
and the male coupling member 32D.
[0106] (5) In the fourth exemplary embodiment, the female coupling
member 32U is disposed below the male coupling member 32D.
Accordingly, the cleaning fluid can be prevented from dropping from
the cleaning fluid supplying hole 55a or the cleaning fluid
discharging hole 56a into the male coupling member 32D on the
application side. As a result, it is possible to further suppress a
possibility that a current might leak out of the coating gun
13.
[0107] (6) In the fourth exemplary embodiment, the cleaning fluid
supplying hole 55a and the cleaning fluid discharging hole 56a are
provided with the tilt in the direction of a gravity. Accordingly,
the cleaning fluid left in the cleaning fluid supplying hole 55a
and the cleaning fluid discharging hole 56a flows with the tilt in
the direction of a gravity. Consequently, the cleaning fluid can be
prevented from dropping into the male coupling member 32D on the
application side. As a result, it is possible to further suppress
the possibility that the current might leak out of the coating gun
13.
[0108] In the first to fourth exemplary embodiments, the method of
fixing the male coupling member 32D and varying the female coupling
member 32U is employed as the method of separating the insulating
and separating valve 32. However, the separating method is not
particularly restricted thereto. For instance, it is also possible
to employ a method of fixing the female coupling member 32U and
varying the male coupling member 32D and a method of varying both
the female coupling member 32U and the male coupling member
32D.
[0109] Although the direction of separation of the insulating and
separating valve 32 is also set to be the vertical direction in the
first to fourth exemplary embodiments, for instance, the invention
is not particularly restricted to the direction but an optional
direction may be set.
[0110] Moreover, the structure of the insulating and separating
valve 32 is not particularly restricted to that of each of the
first to fourth exemplary embodiments. It is sufficient to employ a
structure in which the cleaning path can be formed in the female
coupling member 32U on the non-application side, while the cleaning
path can be prevented from being formed in the male coupling member
32D on the application side. More specifically, although the
cleaning fluid supplying hole 55a and the cleaning fluid
discharging hole 56a are provided on the bottom face 52a of the
concave portion 52 in the female coupling member 32U in the first
to fourth exemplary embodiments, for instance, the invention is not
restricted thereto. For instance, it is also possible to dispose
them in positions in which the cleaning solution can be supplied to
the connecting portion 54 of the female coupling member 32U and the
connecting portion 64 of the male coupling member 32D and can be
discharged therefrom, more specifically, in the vicinity of the
bottom face 52a of the concave portion 52 when the connecting
portions 54 and 64 are provided apart from a position for the
connecting state by a predetermined distance.
[0111] Although the cleaning fluid supplying hole 55a and the
cleaning fluid discharging hole 56a are provided in the female
coupling member 32U in the first to fourth exemplary embodiments,
for instance, the invention is not restricted thereto. For
instance, the cleaning fluid supplying hole 55a and the cleaning
fluid discharging hole 56a may be provided in the male coupling
member 32D.
Fifth Exemplary Embodiment
[0112] FIG. 11 is a view showing a schematic structure of an
electrostatic coating apparatus 2001 to which a connecting device
for a fluid passage according to a fifth exemplary embodiment of
the invention is applied.
[0113] The electrostatic coating apparatus 2001 includes a bell
type coating gun 2013 and a coating material supplying surface 2021
for selectively supplying plural types of electrically conductive
coating materials to the coating gun 2013 through a coating
material supplying path 2022. In the electrostatic coating
apparatus 2001, an electrically conductive coating material which
is charged is sprayed from the coating gun 2013 onto an object to
be coated so that the object to be coated is electrostatically
coated. More specifically, examples of the object to be coated
include a body of a car.
[0114] The coating material supplying source 2021 includes a
coating material tank (not shown) in which plural types of
electrically conductive coating materials (hereinafter referred to
as "coating materials") are stored, a coating material pump (not
shown) for compression transporting the coating material stored in
the coating material tank to the coating material supplying path
2022, and a color change valve CVa for controlling a flow rate of
each coating material.
[0115] The color change valve CVa is provided in a passage for
connecting the coating material tank for storing various coating
materials to the coating material supplying path 2022, and
opens/closes the passage. Consequently, it is possible to control
the flow rate of the coating material to be supplied to the coating
gun 2013 through the coating material supplying path 2022.
[0116] As a mechanism for cleaning the color change valve CVa or
the coating material supplying path 2022 in a color change of the
coating material, moreover, a first cleaning valve SVa1 for
controlling a supply of air (A) and a cleaning fluid (W) is
connected to the color change valve CVa. The color change valve CVa
and the first cleaning valve SVa1 are connected to a controller
2500 through an actuator for driving them, and are operated based
on a control signal sent from the controller 2500.
[0117] The coating material supplying path 2022 is extended from
the color change valve CVa to an intermediate reservoir 2012 which
is connected to the coating gun 2013 and will be described below.
The coating material supplying path 2022 reaches the intermediate
reservoir 2012 which is connected to the coating gun 2013 and will
be described below from the color change valve CVa. In other words,
the coating material supplied from the coating material supplying
source 2021 is once stored in the intermediate reservoir 2012.
[0118] The intermediate reservoir 2012 is provided with a piston
2018 and a servomotor 2015 for precisely controlling a position of
the piston 2018. When the servomotor 2015 is driven to move the
piston 2018 forward (a downward movement in FIG. 11), the coating
material stored in the intermediate reservoir 2012 is compression
transported to the coating gun 2013 through a trigger valve 2016.
When the servomotor 2015 is driven to move the piston 2018 backward
(an upward movement in FIG. 11), moreover, the coating material is
sucked from the coating material supplying path 2022 and is stored
in the intermediate reservoir 2012. The trigger valve 2016 controls
the supply of the coating material from the intermediate reservoir
2012 to the coating gun 2013.
[0119] The coating gun 2013 sprays the coating material supplied
from the coating material supplying path 2022 through the
intermediate reservoir 2012 from a tip thereof toward an object to
be coated. More specifically, a high voltage of approximately
-60000 volts is applied to the coating gun 2013 by means of a
voltage applying unit 2019 to charge and atomize the coating
material supplied from the intermediate reservoir 2012, and sprays
the atomized coating material from the tip in coating. Thus,
electrostatic coating is carried out.
[0120] The coating gun 2013 is fixed to a ram 2014 provided to
enable vertical and transverse reciprocations. Accordingly, it is
possible to spray the coating material onto the object to be coated
while reciprocating the ram 2014 vertically and transversely
depending on a shape of the object to be coated, thereby
maintaining an almost constant interval between the tip of the
coating gun 2013 and the object to be coated.
[0121] As a mechanism for cleaning the coating gun 2013, moreover,
a third cleaning valve SVa3 and a dump valve 2017 are connected to
the coating gun 2013. The third cleaning valve SVa3 controls a
supply of the air (A) and the cleaning fluid (W) which are to be
used for cleaning the coating gun 2013. The dump valve 2017
controls a discharge of a waste liquid of the coating material in a
color change. The trigger valve 2016, the dump valve 2017 and the
third cleaning valve SVa3 are connected to the controller 2500
through an actuator for driving them, and are operated based on a
control signal sent from the controller 2500.
[0122] The coating material supplying path 2022 is provided with an
insulating and separating valve 2032 serving as a connecting device
for a connection or separation of the coating material supplying
path 2022. The insulating and separating valve 2032 includes a
female coupling member 2032U, a male coupling member 2032D for
making a pair with the female coupling member 2032U, and a
separating mechanism 2100 for connecting the female coupling member
2032U to the male coupling member 2032D or separating them from
each other. As will be described below in detail with reference to
FIG. 12, a coating material passage for communicating with the
coating material supplying path 2022 is formed in each of the
female coupling member 2032U and the male coupling member 2032D.
The separating mechanism 2100 relatively moves the female coupling
member 2032U and the male coupling member 2032D and connects the
coating material passages formed therein, thereby forming a single
passage.
[0123] As a mechanism for cleaning the insulating and separating
valve 2032 and the coating material supplying path 2022, a second
cleaning valve SVa2, a cleaning fluid supply switching valve 2035
and a cleaning fluid discharge switching valve 2036 are connected
to the insulating and separating valve 2032. The second cleaning
valve SVa2 controls the supply of the air (A) and the cleaning
fluid (W) which are to be used for cleaning the insulating and
separating valve 2032. The cleaning fluid supply switching valve
2035 controls the supply of the air or the cleaning fluid from the
second cleaning valve SVa2 to the female coupling member 2032U. The
cleaning fluid discharge switching valve 2036 controls a discharge
of the air or the cleaning fluid from the female coupling member
2032U. It is preferable to use deionized water for the cleaning
fluid.
[0124] FIG. 12 is a longitudinal sectional view showing structures
of the female coupling member 2032U and the male coupling member
2032D in the insulating and separating valve 2032. The female
coupling member 2032U and the male coupling member 2032D are
disposed in a vertical direction, and the female coupling member
2032U is provided above the male coupling member 2032D.
[0125] The female coupling member 2032U includes an almost
cylindrical valve body 2051 and a concave portion 2052. The concave
portion 2052 is provided on a lower end side of the valve body 2051
with a concave surface 2052a turned downward.
[0126] A first coating material passage 2053 is formed on an almost
center of the female coupling member 2032U. The first coating
material passage 2053 penetrates through the valve body 2051 and
the concave portion 2052 and reaches the concave surface 2052a of
the concave portion 2052. The first coating material passage 2053
is extended in the vertical direction and is connected to the
coating material supplying source 2021 side of the coating material
supplying path 2022. In the first coating material passage 2053,
moreover, the coating material, the air and the cleaning fluid flow
in a downward direction. The concave portion 2052 is coupled to a
convex portion 2062 of the male coupling member 2032D which will be
described below. Moreover, a part to be an opening of the first
coating material passage 2053 in the concave surface 2052a of the
concave portion 2052 serves as a first connecting portion 2054 to
come in contact with a convex surface 2062a of the convex portion
2062 when the concave portion 2052 is coupled to the convex portion
2062 of the male coupling member 2032D.
[0127] A cleaning fluid supplying hole 2055 penetrating through the
valve body 2051 and the concave portion 2052 is formed in the
female coupling member 2032U. The cleaning fluid supplying hole
2055 is extended from a side part of the valve body 2051 toward the
first connecting portion 2054 in the concave surface 2052a in a
radial direction of the valve body 2051. The air or cleaning fluid
supplied from the second cleaning valve SVa2 (see FIG. 11) is fed
to the cleaning fluid supplying hole 2055 through a cleaning fluid
supplying member 2057 provided in a side part on a right side of
FIG. 12 in the valve body 2051.
[0128] Moreover, a cleaning fluid discharging hole 2056 penetrating
through the valve body 2051 and the concave portion 2052 is formed
in an opposed part to the cleaning fluid supplying hole 2055 in the
female coupling member 2032U. The cleaning fluid discharging hole
2056 is extended from the side part of the valve body 2051 toward
the first connecting portion 2054 in the concave surface 2052a in
the radial direction of the valve body 2051. The air or cleaning
fluid supplied from the cleaning fluid supplying hole 2055 to the
first connecting portion 2054 side flows through the cleaning fluid
discharging hole 2056 and is then discharged to an outside of the
insulating and separating valve 2032 through a cleaning fluid
discharging member 2058 provided in a side part on a left side of
FIG. 12 in the valve body 2051.
[0129] On the other hand, the male coupling member 2032D includes
an almost cylindrical valve body 2061 and the convex portion 2062.
The convex portion 2062 is provided on an upper end side of the
valve body 2061 with the convex surface 2062a turned upward.
[0130] A second coating material passage 2063 is formed on an
almost center of the male coupling member 2032D. The second coating
material passage 2063 penetrates through the valve body 2061 and
the convex portion 2062, and reaches the convex surface 2062a of
the convex portion 2062. The second coating material passage 2063
is extended in the vertical direction and is connected to the
intermediate reservoir 2012 side of the coating material supplying
path 2022. In the second coating material passage 2063, moreover,
the coating material, the air and the cleaning fluid flow in a
downward direction.
[0131] A part to be an opening of the second coating material
passage 2063 in the convex surface 2062a of the convex portion 2062
serves as a second connecting portion 2064. The concave portion
2052 and the convex portion 2062 are coupled to each other to cause
the first connecting portion 2054 and the second connecting portion
2064 to closely come in contact with each other. Consequently, the
first coating material passage 2053 of the female coupling member
2032U is connected to the second coating material passage 2063 of
the male coupling member 2032D so that a single passage is formed.
Although the first connecting portion 2054 and the second
connecting portion 2064 are formed as partial regions of the
concave surface 2052a and the convex surface 2062a respectively in
the exemplary embodiment, the invention is not restricted thereto
but the concave portion 2052 and the convex portion 2062 may be
constituted by separate members.
[0132] Furthermore, a cylindrical seal member holding portion 2065
having a circular groove formed thereon is provided in an outer
peripheral part of the convex portion 2062. A circular seal member
2066 is fitted in the groove. When the convex portion 2062 and the
concave portion 2052 are coupled to each other, the seal member
2066 closely comes in contact with an inner peripheral surface
2052b of the concave portion 2052. Consequently, a space between
the concave portion 2052 and the convex portion 2062, that is, a
space including the first connecting portion 2054, the second
connecting portion 2064, the cleaning fluid supplying hole 2055 and
the cleaning fluid discharging hole 2056 is sealed.
[0133] Moreover, a cylindrical covering portion 2061a is formed on
a tip side of the valve body 2061. The covering portion 2061a
covers the concave portion 2052 and the convex portion 2062 in a
state in which the concave portion 2052 and the convex portion 2062
are coupled to each other, and maintains their coupling state.
[0134] FIG. 13 is a longitudinal sectional view showing a schematic
structure of the separating mechanism 2100. The separating
mechanism 2100 includes a movable housing 2115 to which the female
coupling member 2032U is fixed, and a main cylinder 2111 and a
cylinder 2113 for a cleaning position which are provided in the
movable housing 2115.
[0135] The main cylinder 2111 includes a main rod 2112 which is
provided to enable forward and backward movements in a vertical
direction with respect to a cylinder body thereof. The main
cylinder 2111 is an air cylinder and generates a thrust depending
on an operating pressure to protrude the main rod 2112 when
compressed air is supplied to the cylinder body by means of a
compressor which is not shown.
[0136] The cylinder 2113 for a cleaning position includes a rod
2114 for a cleaning position which is provided to enable forward
and backward movements in a vertical direction with respect to a
cylinder body thereof. The cylinder 2113 for a cleaning position is
an air cylinder and generates a thrust depending on an operating
pressure to protrude the main rod 2112 when compressed air is
supplied to the cylinder body by means of the compressor.
[0137] In a comparison between the main cylinder 2111 and the
cylinder 2113 for a cleaning position, a stroke amount of the main
rod 2112 of the main cylinder 2111 is larger than that of the rod
2114 for a cleaning position of the cylinder 2113 for a cleaning
position. Moreover, a cylinder diameter of the cylinder 2113 for a
cleaning position is larger than that of the main cylinder 2111. In
the case in which the cylinders 2111 and 2113 are driven at an
equal operating pressure, accordingly, the cylinder 2113 for a
cleaning position can protrude the rod 2114 for a cleaning position
by a greater thrust than the main cylinder 2111.
[0138] The movable housing 2115 includes a cylinder holding portion
2117 for holding the main cylinder 2111 and the cylinder 2113 for a
cleaning position, and a frame member 2118 provided slidably in a
vertical direction with respect to the cylinder holding portion
2117.
[0139] The main cylinder 2111 is held by the cylinder holding
portion 2117 with the main rod 2112 turned downward. The cylinder
2113 for a cleaning position is held by the cylinder holding
portion 2117 with the rod 2114 for a cleaning position turned
upward at an upper side of the main rod 2112. In other words, the
main cylinder 2111 and the cylinder 2113 for a cleaning position
generate thrusts in reverse directions to each other. Furthermore,
the compressor for causing the main cylinder 2111 and the cylinder
2113 for a cleaning position to generate the thrusts is connected
to the controller 2500, and is operated based on a control signal
sent from the controller 2500. Accordingly, the thrusts generated
by the cylinders 2111 and 2113 are controlled by the controller
2500.
[0140] A tip of the main rod 2112 and an upper end side of the
female coupling member 2032U are fixed to a lower end side of the
frame member 2118. By moving the main rod 2112 forward and backward
through the main cylinder 2111, therefore, it is possible to
vertically move the female coupling member 2032U together with the
frame member 2118. More specifically, the female coupling member
2032U approaches the male coupling member 2032D when the main rod
2112 is moved forward, and the female coupling member 2032U is
moved apart from the male coupling member 2032D when the main rod
2112 is retreated.
[0141] On the other hand, a stopper 2116 is provided on an upper
end side of the frame member 2118. The rod 2114 for a cleaning
position of the cylinder 2113 for a cleaning position abuts on the
stopper 2116. In other words, when the rod 2114 for a cleaning
position is moved forward, a tip of the rod 2114 for a cleaning
position abuts on the stopper 2116. Consequently, a downward
movement of the frame member 2118 is controlled. When the rod 2114
for a cleaning position is further moved forward in a state in
which the tip of the rod 2114 for a cleaning position abuts on the
stopper 2116, moreover, the frame member 2118 can be upward moved
together with the female coupling member 2032U.
[0142] In the electrostatic coating apparatus 2001 having the
structure described above, filling of the coating material into the
intermediate reservoir 2012, electrostatic coating to be carried
out by the coating material which is filled and cleaning of the
insulating and separating valve 2032 are performed by the
controller 2500 in the following procedures, respectively.
[0143] A procedure for filling the coating material into the
intermediate reservoir 2012 is as follows. First of all, the main
rod 2112 of the main cylinder 2111 is moved forward to move the
female coupling member 2032U downward together with the frame
member 2118, thereby causing the female coupling member 2032U to
approach the male coupling member 2032D (see FIG. 14). As shown in
FIG. 15, consequently, the concave portion 2052 of the female
coupling member 2032U is coupled to the convex portion 2062 of the
male coupling member 2032D and the first connecting portion 2054
closely comes in contact with the second connecting portion 2064 so
that the first coating material passage 2053 is connected to the
second coating material passage 2063, thereby forming a single
coating material passage which reaches the intermediate reservoir
2012 from the coating material supplying source 2021. Next, the
coating material is filled into the intermediate reservoir 2012
from the coating material supplying source 2021 through the coating
material supplying path 2022. When the main rod 2112 is moved
forward, the rod 2114 for a cleaning position in the cylinder 2113
for a cleaning position is retreated. When the frame member 2118 is
moved downward, consequently, the rod 2114 for a cleaning position
is prevented from abutting on the stopper 2116.
[0144] A procedure for filling the coating material into the
intermediate reservoir 2012 as described above and then carrying
out electrostatic coating with the coating material is as follows.
First of all, the main rod 2112 of the main cylinder 2111 is
retreated in the state shown in FIG. 14 to upward move the female
coupling member 2032U together with the frame member 2118, thereby
separating the female coupling member 2032U from the male coupling
member 2032D (see FIG. 13). Consequently, the coating material
supplying path 2022 is divided into an application side which is
conducted to the coating gun 2013 (the intermediate reservoir 2012
side with respect to the male coupling member 2032D) and a
non-application side which is insulated from the coating gun 2013
(the coating material supplying source 2021 side with respect to
the female coupling member 2032U). Subsequently, a high voltage is
applied to the coating gun 2013, and furthermore, the coating
material stored in the intermediate reservoir 2012 is charged, and
at the same time, is sprayed onto an object to be coated.
[0145] A procedure for carrying out the electrostatic coating as
described above and then cleaning the insulating and separating
valve 2032 to perform a color change over the coating material is
as follows. First of all, the main rod 2112 of the main cylinder
2111 and the rod 2114 for a cleaning position in the cylinder 2113
for a cleaning position are moved forward, respectively. Thus, a
clearance is formed between the first connecting portion 2054 of
the female coupling member 2032U and the second connecting portion
2064 of the male coupling member 2032D (see FIG. 16). In other
words, the main cylinder 2111 generates a thrust in a downward
direction to move the main rod 2112 forward, thereby causing the
first connecting portion 2054 to approach the second connecting
portion 2064. On the other hand, the cylinder 2113 for a cleaning
position generates a greater thrust in an upward direction than the
main cylinder 2111 to push the stopper 2116 upward through the rod
2114 for a cleaning position, thereby separating the first
connecting portion 2054 from the second connecting portion 2064.
Thus, the thrusts are generated in opposite directions to each
other by the two cylinders 2111 and 2113, thereby forming a
clearance having a predetermined length d (for instance, d=0.5 mm)
between the first connecting portion 2054 and the second connecting
portion 2064. The length d of the clearance between the first
connecting portion 2054 and the second connecting portion 2064 is
set into a range in which the seal member 2066 does not slip out of
the concave portion 2052, that is, the seal member 2066 of the
convex portion 2062 closely comes in contact with the inner
peripheral surface of the concave portion 2052. Next, the cleaning
fluid is supplied from the cleaning fluid supplying hole 2055 to
the clearance to clean the first connecting portion 2054 and the
second connecting portion 2064. The cleaning fluid subjected to the
cleaning work is discharged from the cleaning fluid discharging
hole 2056.
[0146] When the cleaning fluid is supplied, a force in such a
direction as to separate the first connecting portion 2054 from the
second connecting portion 2064 against the thrust generated in the
main cylinder 2111 by a water pressure of the cleaning fluid, that
is, in an upward direction acts on the first connecting portion
2054. Therefore, the controller 2500 controls the downward thrust
generated in the main cylinder 2111 so as to be greater than the
upward thrust generated by the water pressure of the cleaning fluid
and to be equal to or smaller than the upward thrust generated in
the cylinder 2113 for a cleaning position. Consequently, it is
possible to prevent the seal member 2066 from slipping out of the
concave portion 2052 by the water pressure of the cleaning fluid
while forming the clearance between the first connecting portion
2054 and the second connecting portion 2064 during the cleaning
work.
[0147] According to the fifth exemplary embodiment, the following
advantages can be obtained.
[0148] (1) The thrust generated in the main cylinder 2111 is
controlled to be greater than the force acting in the direction for
separating the first connecting portion 2054 from the second
connecting portion 2064 in the supply of the cleaning fluid and to
be equal to or smaller than the thrust generated in the cylinder
2113 for a cleaning position. Even if the supply of the cleaning
fluid is started, consequently, the interval between the first
connecting portion 2054 and the second connecting portion 2064 can
be properly maintained to prevent the seal member 2066 from
slipping out of the concave portion 2052. Thus, it is possible to
clean the first connecting portion 2054 and the second connecting
portion 2064 without a residue. Moreover, it is possible to clean
the first and second connecting portions 2054 and 2064 without the
residual coating material as described above. Therefore, it is
possible to more reliably prevent a leakage of a current when
charging the coating gun 2013. Accordingly, the coating material
can be charged efficiently. Thus, it is possible to enhance a
coating efficiency and quality of a product.
[0149] (2) The cylinder diameter of the cylinder 2113 for a
cleaning position is set to be greater than that of the main
cylinder 2111. Therefore, also in the case in which the cylinders
2111 and 2113 are operated at an equal operating pressure, for
instance, the thrust generated in the cylinder 2113 for a cleaning
position can be set to be greater than that generated in the main
cylinder 2111. Accordingly, it is possible to reliably form the
clearance between the first connecting portion 2054 and the second
connecting portion 2064, thereby carrying out the cleaning
work.
[0150] (3) The insulating and separating valve 2032 is cleaned with
the deionized water. Consequently, it is possible to carry out the
cleaning work without leaving a hard component such as calcium or
magnesium.
[0151] Although the female coupling member 2032U and the male
coupling member 2032D are disposed in the vertical direction in the
fifth exemplary embodiment, the invention is not restricted
thereto. For instance, the female coupling member and the male
coupling member may be disposed horizontally.
[0152] Although the female coupling member 2032U is caused to
approach the male coupling member 2032D, thereby connecting the
first coating material passage 2053 to the second coating material
passage 2063 in the fifth exemplary embodiment, moreover, the
invention is not restricted thereto. For instance, it is also
possible to cause the male coupling member to approach the female
coupling member, thereby connecting the first and second coating
material passages.
Although the cleaning fluid supplying hole and the cleaning fluid
discharging hole are formed on the female coupling member in the
fifth exemplary embodiment, furthermore, the invention is not
restricted thereto but they may be formed on the male coupling
member.
[0153] In addition, although the seal member 2066 and the seal
member holding portion 2065 for holding the seal member 2066 are
provided in the outer peripheral part of the convex portion 2062 in
the male coupling member 2032D in the fifth exemplary embodiment,
the invention is not restricted thereto.
Variant of Fifth Exemplary Embodiment
[0154] FIG. 17 is a longitudinal sectional view showing structures
of a female coupling member 2232U and a male coupling member 2232D
in an insulating and separating valve 2232 according to a variant
of the fifth exemplary embodiment. As shown in FIG. 17, a seal
member 2266 and a seal member holding portion 2265 for holding the
seal member 2266 may be provided on an inner peripheral surface
2052b of a concave portion 2052 in the female coupling member
2232U. In this case, when a convex portion 2062 is coupled to the
concave portion 2052, the seal member 2266 closely comes in contact
with an outer peripheral surface 2062b of the convex portion 2062.
In the same manner as in the fifth exemplary embodiment,
consequently, there is sealed a space including a first connecting
portion 2054, a second connecting portion 2064, a cleaning fluid
supplying hole 2055 and a cleaning fluid discharging hole 2056
between the concave portion 2052 and the convex portion 2062.
Sixth Exemplary Embodiment
[0155] FIG. 18 is a view showing a schematic structure of an
electrostatic coating apparatus 3001 according to a sixth exemplary
embodiment of the invention.
[0156] The electrostatic coating apparatus 3001 includes a bell
type coating gun 3013 and a coating material supplying source 3021
for selectively supplying plural types of electrically conductive
coating materials to the coating gun 3013 through a coating
material supplying path 3022. The electrostatic coating apparatus
3001 sprays an electrically conductive coating material which is
charged from the coating gun 3013 onto an object to be coated,
thereby carrying out electrostatic coating over the object to be
coated. More specifically, examples of the object to be coated
include a body of a car.
[0157] The coating material supplying source 3021 includes a
coating material tank (not shown) in which plural types of
electrically conductive coating materials (hereinafter referred to
as "coating materials") are stored, a coating material pump (not
shown) for compression transporting the coating material stored in
the coating material tank to the coating material supplying path
3022, and a color change valve CVb for controlling a flow rate of
each coating material.
[0158] The color change valve CVb is provided in a passage for
connecting the coating material tank for storing various coating
materials to the coating material supplying path 3022, and
opens/closes the passage. Consequently, it is possible to control
the flow rate of the coating material to be supplied to the coating
gun 3013 through the coating material supplying path 3022.
[0159] As a mechanism for cleaning the color change valve CVb or
the coating material supplying path 3022 in a color change of the
coating material, moreover, a first cleaning valve SVb1 for
controlling a supply of air (A) and a cleaning fluid (W) is
connected to the color change valve CVb. The color change valve CVb
and the first cleaning valve SVb1 are connected to a controller
3500 through an actuator for driving them, and are operated based
on a control signal sent from the controller 3500.
[0160] The coating material supplying path 3022 is extended from
the color change valve CVb to an intermediate reservoir 3012 which
is connected to the coating gun 3013 and will be described below.
The coating material supplying path 3022 reaches the intermediate
reservoir 3012 which is connected to the coating gun 3013 and will
be described below from the color change valve CVb. In other words,
the coating material supplied from the coating material supplying
source 3021 is once stored in the intermediate reservoir 3012.
[0161] The intermediate reservoir 3012 is provided with a piston
3018 and a servomotor 3015 for precisely controlling a position of
the piston 3018. When the servomotor 3015 is driven to move the
piston 3018 forward (a downward movement in FIG. 18), the coating
material stored in the intermediate reservoir 3012 is compression
transported to the coating gun 3013 through a trigger valve 3016.
When the servomotor 3015 is driven to move the piston 3018 backward
(an upward movement in FIG. 18), moreover, the coating material is
sucked from the coating material supplying path 3022 and is stored
in the intermediate reservoir 3012. The trigger valve 3016 controls
the supply of the coating material from the intermediate reservoir
3012 to the coating gun 3013.
[0162] The coating gun 3013 sprays the coating material supplied
from the coating material supplying path 3022 through the
intermediate reservoir 3012 from a tip thereof toward an object to
be coated. More specifically, a high voltage of approximately
-60000 volts is applied to the coating gun 3013 by means of a
voltage applying unit 3019 to charge and atomize the coating
material supplied from the intermediate reservoir 3012 and to then
spray the atomized coating material from the tip in coating. Thus,
electrostatic coating is carried out.
[0163] The coating gun 3013 is fixed to a ram 3014 provided to
enable vertical and transverse reciprocations. Accordingly, it is
possible to spray the coating material onto the object to be coated
while reciprocating the ram 3014 vertically and transversely
depending on a shape of the object to be coated, thereby
maintaining an almost constant interval between the tip of the
coating gun 3013 and the object to be coated.
[0164] As a mechanism for cleaning the coating gun 3013, moreover,
a third cleaning valve SVb3 and a dump valve 3017 are connected to
the coating gun 3013. The third cleaning valve SVb3 controls a
supply of the air (A) and the cleaning fluid (W) which are to be
used for cleaning the coating gun 3013. The dump valve 3017
controls a discharge of a waste liquid of the coating material in a
color change. The trigger valve 3016, the dump valve 3017 and the
third cleaning valve SVb3 are connected to the controller 3500
through an actuator for driving them, and are operated based on a
control signal sent from the controller 3500.
[0165] The coating material supplying path 3022 is provided with an
insulating and separating valve 3032 serving as an insulating
mechanism and a high speed grounding device 3040 in order from the
color change valve CVb side toward the coating gun 3013 side.
[0166] The insulating and separating valve 3032 includes a female
coupling member 3032U fixed to a movable member 3033 and a male
coupling member 3032D making a pair with the female coupling member
3032U. The movable member 3033 is vertically moved by means of an
air cylinder 3034 fixed to the ram 3014. When the movable member
3033 is moved downward, accordingly, the female coupling member
3032U is connected to the male coupling member 3032D. Consequently,
it is possible to supply the coating material from the coating
material supplying source 3021 to the intermediate reservoir 3012.
When the movable member 3033 is moved upward, moreover, the female
coupling member 3032U is separated from the male coupling member
3032D.
[0167] As will be described below in detail, when electrostatic
coating is to be carried out through an application of a high
voltage to the coating gun 3013, the female coupling member 3032U
and the male coupling member 3032D in the insulating and separating
valve 3032 are separated from each other. In the electrostatic
coating, therefore, the coating material supplying path 3022 is
divided into an application side which is conducted to the coating
gun 3013 and a non-application side which is insulated from the
coating gun 3013. More specifically, the coating gun 3013 side in
the coating material supplying path 3022 with respect to the male
coupling member 3032D is conducted to the coating gun 3013.
Therefore, the same side serves as the application side in the
electrostatic coating so that a high voltage is applied. On the
other hand, the coating material supplying source 3021 side in the
coating material supplying path 3022 with respect to the female
coupling member 3032U is insulated from the coating gun 3013.
Therefore, the same side serves as the non-application side in the
electrostatic coating.
[0168] The high speed grounding device 3040 includes a joint
portion 3041 provided in the coating material supplying path 3022,
a discharging fluid supplying path 3042 connected to the joint
portion 3041, and a supplying device 3043 for supplying the air (A)
and the electrically conductive fluid (W) to the discharging fluid
supplying path 3042, and discharges a residual electric charge of
the coating material supplying path 3022 to which a high voltage is
applied in the electrostatic coating.
[0169] FIG. 19 is a sectional view showing a structure of the joint
portion 3041. The joint portion 3041 is almost plate-shaped and is
formed by an electrically conductive material such as SUS. In the
joint portion 3041, two passages including a coating material
passage 3044 and a discharging passage 3045 are formed hollowly in
parallel with each other.
[0170] An insulating and separating valve side 3022U of the coating
material supplying path 3022 is connected to an inlet port of the
coating material passage 3044 through a first coupling member 3461,
and a coating valve side 3022D of the coating material supplying
path 3022 is connected to an outlet port of the coating material
passage 3044 through a second coupling member 3462. On the other
hand, a supplying device side 3042U of the discharging fluid
supplying path 3042 is connected to the inlet port of the
discharging passage 3045 through a third coupling member 3463, and
an outlet port side 3042D of the discharging fluid supplying path
3042 is connected to an outlet port side of the discharging passage
3045 through a fourth coupling member 3464. By connecting the
coating material supplying path 3022 and the discharging fluid
supplying path 3042 to the joint portion 3041 as described above,
it is possible to conduct the discharging fluid supplying path 3042
to the application side of the coating material supplying path
3022. Moreover, the joint portion 3041 is accommodated in a
protecting case formed by a resin (which is not shown).
[0171] Returning to FIG. 18, the supplying device 3043 includes a
pump for supplying an electrically conductive fluid to the
discharging fluid supplying path 3042 and an air compressor (not
shown) for supplying air to the discharging fluid supplying path
3042, and furthermore, a discharging fluid supply switching valve
3046 for opening/closing a passage to connect the pump or the air
compressor to the discharging fluid supplying path 3042.
Consequently, it is possible to control a flow rate of the
electrically conductive fluid or the air which flows through the
discharging fluid supplying path 3042. In the exemplary embodiment,
deionized water is used for the electrically conductive fluid to be
supplied to the discharging fluid supplying path 3042 through the
supplying device 3043. Moreover, the supplying device 3043 is
connected to the controller 3500 and is operated based on a control
signal sent from the controller 3500.
[0172] In addition, the discharging fluid supplying path 3042 is
grounded on the supplying device 3043 side with respect to the
joint portion 3041. In other words, the coating material supplying
path 3022 is insulated from the grounding side in a state in which
the electrically conductive fluid is not supplied into the
discharging fluid supplying path 3042. On the other hand, when the
electrically conductive fluid is supplied from the supplying device
3043 into the discharging fluid supplying path 3042, the coating
material supplying path 3022 is conducted to the grounding side
through the electrically conductive fluid in the joint portion 3041
and the discharging fluid supplying path 3042.
[0173] As a mechanism for cleaning the insulating and separating
valve 3032 or the coating material supplying path 3022, moreover, a
second cleaning valve SVb2, a cleaning fluid supply switching valve
3035 and a cleaning fluid discharge switching valve 3036 are
connected to the insulating and separating valve 3032. The second
cleaning valve SVb2 controls a supply of the air (A) and the
cleaning fluid (W) which are to be used in the cleaning work for
the insulating and separating valve 3032. The cleaning fluid supply
switching valve 3035 controls the supply of the air or the cleaning
fluid from the second cleaning valve SVb2 to the female coupling
member 3032U. The cleaning fluid discharge switching valve 3036
controls a discharge of the air or the cleaning fluid from the
female coupling member 3032U.
[0174] In the electrostatic coating apparatus 3001 having the
structure described above, electrostatic coating and a color change
for a coating material are carried out by the controller 3500 in
the following procedure. First of all, the female coupling member
3032U and the male coupling member 3032D in the insulating and
separating valve 3032 are connected to each other and a coating
material having a predetermined color is then supplied from the
coating material supplying source 3021 to the intermediate
reservoir 3012. When the supply of the coating material to the
intermediate reservoir 3012 is ended, subsequently, the female
coupling member 3032U and the male coupling member 3032D in the
insulating and separating valve 3032 are separated from each other.
Next, a high voltage is applied to the coating gun 3013 and the
coating material stored in the intermediate reservoir 3012 is
charged and sprayed onto an object to be coated.
[0175] Subsequently to the electrostatic coating described above,
moreover, the color change for the coating material is carried out
in the following procedure. First of all, when the application of
the high voltage to the coating gun 3013 is ended and the
electrostatic coating is thus completed, the high speed grounding
device 3040 is driven to discharge the residual electric charge on
the coating material supplying path 3022 side. More specifically,
the electrically conductive fluid is started to be supplied from
the supplying device 3043 to the discharging fluid supplying path
3042. Consequently, the residual electric charge in the coating
material supplying path 3022 is discharged. After the discharge of
the residual electric charge in the coating material supplying path
3022 is completed, furthermore, the supply of the electrically
conductive fluid from the supplying device 3043 is stopped and the
supply of the air is started. Thus, the electrically conductive
fluid in the discharging fluid supplying path 3042 is discharged so
that the coating material supplying path 3022 is brought into an
insulating state from the grounding side.
[0176] Next, the female coupling member 3032U and the male coupling
member 3032D in the insulating and separating valve 3032 are
connected to each other and the cleaning valves SVb1 to SVb3 are
then driven to clean the coating material supplying path 3022, the
insulating and separating valve 3032, the intermediate reservoir
3012 and the coating gun 3013. Thereafter, a predetermined coating
material is started to be supplied to the coating material
supplying path 3022.
[0177] FIG. 20 is a chart showing a time variation in a voltage
value of the coating material supplying path 3022 after the end of
the application of the high voltage. In the case in which the high
speed grounding device 3040 is not used, that is, the deionized
water is not supplied to the discharging fluid supplying path 3042,
the voltage value of the coating material supplying path 3022 is
reduced gradually through a spontaneous discharge after the
application of the high voltage is ended at a time as shown in a
broken line of FIG. 20.
[0178] On the other hand, in the case in which the high speed
grounding device 3040 is used, it is possible to discharge the
residual electric charge in the coating material supplying path
3022 more rapidly than in the case in which the high speed
grounding device 3040 is not used as shown in a solid line of FIG.
20. More specifically, the deionized water is started to be
supplied from the supplying device 3043 to the discharging fluid
supplying path 3042 immediately after the application of the high
voltage is ended at the time t1. At a time t2, then, the coating
material supplying path 3022 and the grounding side are conducted
through the deionized water flowing through the discharging fluid
supplying path 3042 depending on the arrival of the deionized water
supplied from the supplying device 3043 at the joint portion 3041
so that the residual electric charge in the coating material
supplying path 3022 is discharged to the grounding side.
Consequently, the voltage value of the coating material supplying
path 3022 is reduced after the time t2 and reaches almost zero at a
time t3.
[0179] According to the sixth exemplary embodiment, the following
advantages can be obtained.
[0180] (1) There are provided the discharging fluid supplying path
3042 conducted to a part on the application side of the coating
material supplying path 3022 through the joint portion 3041 and
grounded, and the supplying device 3043 for supplying the
electrically conductive fluid to the discharging fluid supplying
path 3042. Consequently, the electric charge left on the
application side of the coating material supplying path 3022
through the application of the high voltage to the coating gun 3013
can be rapidly discharged to the grounding side through the
electrically conductive fluid flowing through the discharging fluid
supplying path 3042.
[0181] Also in the case in which the electrically conductive fluid
is caused to flow through the separate discharging fluid supplying
path 3042 from the coating material supplying path 3022 so that a
leakage or a spark occurs, moreover, the coating material supplying
path 3022 can be prevented from being damaged. Accordingly, it is
possible to prevent a deterioration in a cleaning property of the
coating material supplying path 3022. Also in the case in which
there is caused such a damage that the discharging fluid supplying
path 3042 is to be replaced, furthermore, it is possible to carry
out the replacement more inexpensively than that in the case in
which the coating material supplying path 3022 is replaced. In
addition, there is no possibility that the electrically conductive
fluid might mix with the coating material. Therefore, it is
possible to use various fluids in addition to the deionized water
as the electrically conductive fluid.
[0182] (2) After the application of the high voltage to the coating
gun 3013 is ended, the electrically conductive fluid is started to
be supplied to the discharging fluid supplying path 3042.
Consequently, it is possible to rapidly discharge the electric
charge left on the application side of the coating material
supplying path 3022 after the electrostatic coating. Thus, it is
possible to reduce a time taken for connecting the insulating and
separating valve 3032. Accordingly, it is possible to quickly start
the work for cleaning the coating material supplying path 3022 or
the insulating and separating valve 3032 after the electrostatic
coating. Thus, it is possible to enhance a coating efficiency.
[0183] (3) By using, as the electrically conductive fluid, the
deionized water having a smaller amount of impurity such as
chlorine than clean water, it is possible to prevent a current from
leaking in non-grounding.
[0184] (4) The electrically conductive fluid is supplied to the
discharging fluid supplying path 3042 to discharge the residual
electric charge from the application side of the coating material
supplying path 3022, and the air is then supplied to the
discharging fluid supplying path 3042 through the supplying device
3043. Consequently, it is possible to discharge the electrically
conductive fluid left in the discharging fluid supplying path 3042.
Thus, it is possible to prevent a current from leaking out of the
application side of the coating material supplying path 3022
through the discharging fluid supplying path 3042 while the
electrically conductive fluid is not supplied.
[0185] Although the insulating and separating valve 3032 serving as
the insulating mechanism is provided in the coating material
supplying path 3022 to divide the coating material supplying path
3022 into the application side and the non-application side in the
sixth exemplary embodiment, the invention is not restricted
thereto. For instance, it is also possible to provide an insulating
tube in the coating material supplying path, thereby dividing the
coating material supplying path into the application side and the
non-application side.
INDUSTRIAL APPLICABILITY
[0186] The invention can be utilized in an electrostatic coating
apparatus for applying a high voltage to an electrically conductive
coating material, thereby carrying out coating.
EXPLANATION OF DESIGNATION
[0187] 1 electrostatic coating apparatus [0188] 11 coating material
supplying path [0189] 13 coating gun [0190] 18 movable member
[0191] 19 air cylinder [0192] 32 insulating and separating valve
[0193] 32D male coupling member [0194] 32U female coupling member
[0195] 52 concave portion [0196] 53 coating material supplying
passage [0197] 54 connecting portion [0198] 55a cleaning fluid
supplying hole [0199] 56a cleaning fluid discharging hole [0200]
61a guide portion [0201] 62 convex portion [0202] 63 coating
material supplying passage [0203] 64 connecting portion [0204] 100
separating mechanism [0205] 201 seal member [0206] 2001
electrostatic coating apparatus [0207] 2013 coating gun [0208] 2012
intermediate reservoir [0209] 2021 coating material supplying
source [0210] 2022 coating material supplying path [0211] 2032,
2232 insulating and separating valve (connecting device) [0212]
2032U, 2232U female coupling member [0213] 2052 concave portion
[0214] 2053 first coating material passage [0215] 2054 first
connecting portion [0216] 2055 cleaning fluid supplying hole [0217]
2056 cleaning fluid discharging hole [0218] 2032D, 2232D male
coupling member [0219] 2062 convex portion [0220] 2063 second
coating material passage [0221] 2064 second connecting portion
[0222] 2065, 2265 seal member holding portion [0223] 2066, 2266
seal member [0224] 2100 separating mechanism [0225] 2111 main
cylinder (first operating mechanism) [0226] 2113 cylinder for
cleaning position (second operating mechanism) [0227] 3001
electrostatic coating apparatus [0228] 3013 coating gun [0229] 3021
coating material supplying source [0230] 3022 coating material
supplying path [0231] 3032 insulating and separating valve
(insulating mechanism) [0232] 3032U female coupling member [0233]
3032D male coupling member [0234] 3040 high speed grounding device
[0235] 3041 joint portion [0236] 3042 discharging fluid supplying
path (fluid supplying path) [0237] 3043 supplying device (fluid
supplying device, gas supplying device)
* * * * *