U.S. patent application number 14/036737 was filed with the patent office on 2014-03-27 for apparatus and method for abrasive water jet machining.
This patent application is currently assigned to SUGINO MACHINE LIMITED.. The applicant listed for this patent is Sugino Machine Limited.. Invention is credited to Masaru OGAWA, Nobuyuki TERA, Masashi TSUNEMOTO.
Application Number | 20140087635 14/036737 |
Document ID | / |
Family ID | 50339283 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140087635 |
Kind Code |
A1 |
OGAWA; Masaru ; et
al. |
March 27, 2014 |
APPARATUS AND METHOD FOR ABRASIVE WATER JET MACHINING
Abstract
To provide an abrasive water jet machining apparatus in which
the machining accuracy and machining efficiency is improved by
improving the flowability of an abrasive through a nozzle. An
abrasive water jet machining apparatus performs machining by
directing an abrasive water jet at a workpiece, the abrasive water
jet being composed of a mixture of a high-pressure processing fluid
with an abrasive. The machining apparatus includes: a nozzle that
directs the abrasive water jet; a high-pressure water supply device
that supplies the processing fluid to the nozzle; and an abrasive
supply device that supplies the abrasive to the processing fluid.
The abrasive is composed of a coated abrasive, the coated abrasive
being produced by coating a surface of an abrasive material
composed of abrasive grains with a water-repellent material or flow
promoting material. The abrasive supply device 8 supplies the
coated abrasive to the nozzle.
Inventors: |
OGAWA; Masaru; (Toyama-shi,
JP) ; TERA; Nobuyuki; (Kurobe-shi, JP) ;
TSUNEMOTO; Masashi; (Uozu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sugino Machine Limited. |
Uozu-shi |
|
JP |
|
|
Assignee: |
SUGINO MACHINE LIMITED.
Uozu-shi
JP
|
Family ID: |
50339283 |
Appl. No.: |
14/036737 |
Filed: |
September 25, 2013 |
Current U.S.
Class: |
451/40 ; 451/88;
451/99 |
Current CPC
Class: |
B24C 11/005 20130101;
B24C 11/00 20130101; B24C 3/04 20130101 |
Class at
Publication: |
451/40 ; 451/99;
451/88 |
International
Class: |
B24C 11/00 20060101
B24C011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2012 |
JP |
2012-213225 |
Claims
1. An abrasive water jet machining apparatus that performs
machining by directing an abrasive water jet at a workpiece, the
abrasive water jet being composed of a mixture of a high-pressure
processing fluid with an abrasive, comprising: a nozzle that
directs the abrasive water jet; a processing fluid supply portion
that supplies the processing fluid to the nozzle; and an abrasive
supply portion that supplies the abrasive to the processing fluid,
wherein the abrasive is composed of a coated abrasive, the coated
abrasive being produced by coating a surface of an abrasive
material composed of abrasive grains with a water-repellent
material or flow promoting material, and the abrasive supply
portion supplies the coated abrasive to the nozzle.
2. The abrasive water jet machining apparatus according to claim 1,
wherein the coated abrasive has a property of floating in the
processing fluid.
3. The abrasive water jet machining apparatus according to claim 1,
wherein the abrasive supply portion includes: an abrasive material
supply portion that supplies the abrasive material to the
processing fluid; a coated abrasive supply portion that supplies
the coated abrasive to the processing fluid; and a switching unit
for selectively supplying the abrasive material supplied from the
abrasive material supply portion or/and the coated abrasive
supplied from the coated abrasive supply portion.
4. An abrasive water jet machining apparatus that performs
machining by directing an abrasive water jet at a workpiece, the
abrasive water jet being composed of a mixture of a high-pressure
processing fluid with an abrasive, comprising: a nozzle that
directs the abrasive water jet; a processing fluid supply portion
that supplies the processing fluid to the nozzle; an abrasive
supply portion that supplies the abrasive to the processing fluid;
and a liquid supply portion that supplies a water-repellent
material or flow promoting material to the processing fluid or the
abrasive.
5. The abrasive water jet machining apparatus according to claim 1,
wherein the water-repellent material or flow promoting material is
composed of any one of a fluorine-based material, silicon-based
material, a coating material composed of a mixture of a
fluorine-based material or a silicon-based material and an oily raw
material, paraffin, and fats.
6. The abrasive water jet machining apparatus according to claim 1,
further comprising: a catcher tank that stores liquid for machining
the workpiece under liquid; and a discharge port that discharges
the liquid stored in the catcher tank, wherein the coated abrasive
floating on the liquid is discharged and recovered from the
discharge port.
7. The abrasive water jet machining apparatus according to claim 6,
further comprising a liquid level adjusting device that adjusts a
liquid level of the liquid by adjusting a height of the discharge
port.
8. An abrasive water jet machining method in which machining is
performed by directing an abrasive water jet at a workpiece, the
abrasive water jet being composed of a mixture of a high-pressure
processing fluid with an abrasive, the method comprising: producing
a coated abrasive as the abrasive by coating a surface of an
abrasive material composed of abrasive grains with a
water-repellent material or flow promoting material.
9. An abrasive water jet machining method in which machining is
performed by directing an abrasive water jet at a workpiece, the
abrasive water jet being composed of a mixture of a high-pressure
processing fluid with an abrasive, the method comprising: supplying
a water-repellent material or flow promoting material to the
processing fluid or the abrasive.
10. The abrasive water jet machining apparatus according to claim
2, wherein the abrasive supply portion includes: an abrasive
material supply portion that supplies the abrasive material to the
processing fluid; a coated abrasive supply portion that supplies
the coated abrasive to the processing fluid; and a switching unit
for selectively supplying the abrasive material supplied from the
abrasive material supply portion or/and the coated abrasive
supplied from the coated abrasive supply portion.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to an apparatus and method for
abrasive water jet machining, in which machining is performed by
directing an abrasive water jet at a workpiece, the abrasive water
jet being composed of a mixture of a high-pressure processing fluid
with an abrasive.
[0003] 2. Related Art
[0004] As a machining apparatus for performing cutting on
hard-to-machine workpieces of glass, stones, synthetic resin,
composite materials such as carbon fiber reinforced plastic (CFRP),
or the like, there is known an abrasive water jet machining
apparatus in which a general abrasive (abrasive material), such as
garnet, is mixed into high-pressure water.
[0005] A related art technology in which an abrasive (abrasive
material) is improved in materials, surface shape, grain diameter,
grain diameter distribution or the like in order to efficiently
realize suitable cutting is disclosed, for example, in Japanese
Unexamined Patent Application Publication No. H8-1515 (see
paragraphs [0004] to [0008] and FIG. 1) and Japanese Patent No.
4653962 (see paragraphs [0041] to [0044] and FIG. 3).
[0006] The Japanese Unexamined Patent Application Publication No.
H8-1515 discloses an abrasive (abrasive material) of ceramic fine
grains each having an edge portion, each of the grains having a
size in the range of 0.2 to 3 mm. The Japanese Patent No. 4653962
discloses an abrasive jet machining method using spherical zircon
beads with a grain diameter in the range of 10 to 800 .mu.m, the
grain having a nearly truly spherical shape.
[0007] However, the Japanese Unexamined Patent Application
Publication No. H8-1515 and Japanese Patent No. 4653962 do not
disclose an effective technology for preventing the abrasive from
clogging a nozzle. Especially in recent years, in order to perform
accurate cutting of workpieces of different materials, shapes, and
thicknesses, it is necessary to perform a machining with the
optimum jet diameter as appropriate on the workpieces different in
final cutting width. Unfortunately, when the nozzle diameter is
reduced in order to make the jet diameter smaller, the nozzle
diameter is brought close to the grain diameter of the abrasive,
causing a clogging of the nozzle with the abrasive more likely to
occur.
[0008] Furthermore, if the abrasive is non-water-repellent
(non-hydrophobic), an abrasive material adheres to a wall surface
of an abrasive material passage with water adhering thereto as a
contact body, and further, the subsequent abrasive material adheres
to the abrasive material with the water as a contact body, leading
to chained agglomeration of the abrasive materials, thereby causing
the problems of a reduction in the inner diameter (airway) of the
abrasive material passage and a decrease in flowability.
[0009] In this case, the problem is that the abrasive materials
adhering to an inner wall of the abrasive material passage cause a
blockage in a flow passage and cut off the air pulled in by a jet,
resulting in feed failure of the abrasive materials.
SUMMARY
[0010] Accordingly, the present invention has been made under such
circumstances, and an object of the present invention is to provide
an apparatus and method for abrasive water jet machining, in which
the machining accuracy and machining efficiency is improved by
improving the flowability of an abrasive through a nozzle.
[0011] In order to address the above-mentioned problems, a first
aspect of the present invention provides an abrasive water jet
machining apparatus that performs machining by directing an
abrasive water jet at a workpiece, the abrasive water jet being
composed of a mixture of a high-pressure processing fluid with an
abrasive. The abrasive water jet machining apparatus includes: a
nozzle that directs the abrasive water jet; a processing fluid
supply portion that supplies the processing fluid to the nozzle;
and an abrasive supply portion that supplies the abrasive to the
processing fluid. The abrasive is composed of a coated abrasive,
the coated abrasive being produced by coating a surface of an
abrasive material composed of abrasive grains with a
water-repellent material or flow promoting material. The abrasive
supply portion supplies the coated abrasive to the nozzle.
[0012] With this construction, the abrasive supply portion for
supplying the abrasive to the processing fluid supplies the coated
abrasive produced by coating the surface of the abrasive material
composed of abrasive grains with the water-repellent material or
flow promoting material. Thus, the coated abrasive repels the
processing fluid or promotes flowability by surface tension acting
on the processing fluid existing among the grains of the coated
abrasive, thereby preventing the abrasive material from adhering to
a wall surface of an abrasive material passage and always
establishing an open airway that allows air to flow. Consequently,
the flowability of the abrasive through the nozzle can be
improved.
[0013] Thus, in the abrasive water jet machining apparatus, the
abrasive in the processing fluid at the time of machining the
workpiece with the abrasive water jet is uniformly dispersed and
smoothly flows without agglomeration. Therefore, during a machining
work, interruption of the work due to clogging of the nozzle, etc.
with the abrasive can be prevented.
[0014] Furthermore, because the coated abrasive is less likely to
cause clogging and has excellent fluidity, the amount of the
abrasive in the abrasive water jet can be increased so as to
improve machinability. It is therefore possible to shorten cutting
time and speed up the processing, and, at the time of machining,
provide smooth finishing of the machining surface as compared with
the machining with the related art abrasive material.
[0015] Also, preferably, the coated abrasive has a property of
floating in the processing fluid.
[0016] With this construction, because the coated abrasive has a
property of floating, the sinking and deposition of the abrasive
grains of the coated abrasive in the nozzle can be reduced, thereby
it is possible to prevent the coated abrasive from clogging the
nozzle.
[0017] Furthermore, preferably, the abrasive supply portion
includes: an abrasive material supply portion that supplies the
abrasive material to the processing fluid; a coated abrasive supply
portion that supplies the coated abrasive to the processing fluid;
and switching unit for selectively supplying the abrasive material
supplied from the abrasive material supply portion or the coated
abrasive supplied from the coated abrasive supply portion.
[0018] With this construction, the abrasive to be supplied into the
nozzle can be selectively changed between the abrasive material and
the coated abrasive by switching the switching unit. Therefore, the
abrasive water jet machining apparatus can machine the workpiece by
effectively utilizing the property of the abrasive material that is
more excellent in machinability and the property of the coated
abrasive that is more excellent in non-agglomerating property or
flowability.
[0019] A second aspect of the present invention provides an
abrasive water jet machining apparatus that performs machining by
directing an abrasive water jet at a workpiece, the abrasive water
jet being composed of a mixture of a high-pressure processing fluid
with an abrasive. The abrasive water jet machining apparatus
includes: a nozzle that directs the abrasive water jet; a
processing fluid supply portion that supplies the processing fluid
to the nozzle; an abrasive supply portion that supplies the
abrasive to the processing fluid; and a liquid supply portion that
supplies a water-repellent material or flow promoting material to
the processing fluid or the abrasive.
[0020] With this construction, because the liquid supply portion
supplies the water-repellent material or flow promoting material to
the processing fluid or abrasive, the water-repellent material
having surface tension or the flow promoting material having the
function of promoting the flowability is mixed into the processing
fluid or abrasive, thereby improving the flowability of the
processing fluid or the abrasive. Consequently, a trouble due to
deterioration in flowability can be avoided.
[0021] Moreover, preferably, the water-repellent material or flow
promoting material is composed of any one of a fluorine-based
material, silicon-based material, a coating material composed of a
mixture of a fluorine-based material or a silicon-based material
and an oily raw material, paraffin, and fats.
[0022] With this construction, because the water-repellent material
or flow promoting material is composed of any one of a
fluorine-based material, silicon-based material, a coating material
composed of a mixture of a fluorine-based material or a
silicon-based material and an oily raw material, paraffin, and
fats, each of the abrasive grains has the function of promoting the
water repellency or flowability. Therefore, the grains of the
coated abrasive coated with the water-repellent material have the
hydrophobic property of repelling the processing fluid with one
another, and thus repel the processing fluid with one another in a
state of being mixed in the water jet, thereby allowing preventing
agglomeration and eliminating a clogging of the nozzle.
Furthermore, the grains of the coated abrasive coated with the flow
promoting material are reduced in flow resistance during flowing,
thereby allowing preventing agglomeration and eliminating a
clogging of the nozzle.
[0023] It should be noted that the water-repellent material or flow
promoting material may include any material other than the above if
it has water repellency or flowability, and is not limited to the
above-described coating material.
[0024] Also, preferably, the abrasive water jet machining apparatus
further includes: a catcher tank that filled with liquid that
receive and absorb water jet and its energy for machining the
workpiece under the liquid; and a discharge port that discharges
the liquid stored in the catcher tank. The coated abrasive floating
in the liquid is discharged and recovered from the discharge
port.
[0025] With this construction, the coated abrasive floating in the
liquid stored in the catcher tank is discharged and recovered from
the discharge port, thereby enabling recycled use thereof.
Furthermore, the non-water-repellent abrasive material sinks to an
inner bottom of the catcher tank in the liquid and therefore can be
recovered separately from the floating coated abrasive.
[0026] Preferably, the abrasive water jet machining apparatus
further includes a liquid level adjusting device that adjusts a
liquid level of the liquid by adjusting a height of the discharge
port.
[0027] With this construction, by raising the height of the
discharge port with the liquid level adjusting device, the liquid
level inside the catcher tank can be raised. Also, by lowering the
height of the discharge port with the liquid level adjusting
device, the liquid level inside the catcher tank can be lowered and
adjusted as appropriate according to the thickness of the
workpiece.
[0028] In addition, a third aspect of the present invention
provides an abrasive water jet machining method in which machining
is performed by directing an abrasive water jet at a workpiece, the
abrasive water jet being composed of a mixture of a high-pressure
processing fluid with an abrasive. The method includes producing a
coated abrasive as the abrasive by coating a surface of an abrasive
material composed of abrasive grains with a water-repellent
material or flow promoting material.
[0029] With this construction, the coated abrasive produced by
coating the surface of the abrasive material composed of abrasive
grains with the water-repellent material or flow promoting material
is supplied to the processing fluid. Thus, in the case of the
coated abrasive coated with the water-repellent material, the
coated abrasives repel the processing fluid with one another by
surface tension acting on the processing fluid existing among the
abrasive grains. Furthermore, in the case of the coated abrasive
coated with the flow promoting material, each of the abrasive
grains is improved in flowability. Therefore, with the coated
abrasive coated with the water-repellent material or flow promoting
material, agglomeration in the nozzle or the like or clogging can
be eliminated. As a result, the abrasive water jet machining method
allows uniform dispersion and smooth flow of the grains of the
coated abrasive in the water jet at the time of abrasive water jet
machining.
[0030] Also, a fourth aspect of the present invention provides an
abrasive water jet machining method in which machining is performed
by directing an abrasive water jet at a workpiece, the abrasive
water jet being composed of a mixture of a high-pressure processing
fluid with an abrasive. The method includes supplying a
water-repellent material or flow promoting material to the
processing fluid or the abrasive.
[0031] With this construction, by using the coated abrasive having
a property of floating, the sinking and deposition of the grains of
the coated abrasive in the nozzle can be reduced, thereby allowing
preventing the coated abrasive from clogging the nozzle.
[0032] According to the present invention, the present invention is
to provide an apparatus and method for abrasive water jet
machining, in which the machining accuracy and machining efficiency
is improved by improving the flowability of an abrasive through a
nozzle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Embodiments of the present invention will be described in
detail based on the following drawings, in which:
[0034] FIG. 1 is a perspective view of the essential parts of an
abrasive water jet machining apparatus according to an embodiment
of the present invention;
[0035] FIG. 2 is a schematic view of the essential parts of the
abrasive water jet machining apparatus according to the embodiment
of the present invention;
[0036] FIG. 3 is an enlarged longitudinal sectional view of a
nozzle shown in FIG. 2;
[0037] FIGS. 4A to 4C are enlarged views of the essential parts of
a carrier rotor of the abrasive supply device of the abrasive water
jet machining apparatus according to the embodiment of the present
invention, wherein FIG. 4A is a longitudinal sectional view, FIG.
4B is a side view, and FIG. 4C is a longitudinal sectional view
showing the state when the carrier rotor is rotated;
[0038] FIG. 5 is a schematic view of a catcher tank of the abrasive
water jet machining apparatus according to the embodiment of the
present invention;
[0039] FIGS. 6A and 6B are schematic views showing a state actually
seen with an electron microscope, wherein FIG. 6A is an enlarged
schematic view showing abrasive grains of an non-coated abrasive
material, and FIG. 6B is an enlarged schematic view showing
abrasive grains of a coated abrasive coated with a water-repellent
material;
[0040] FIG. 7A is a perspective view showing a state in which a
water droplet is put onto a pile of coated abrasive with abrasive
grains of garnet having a grain diameter of #200 coated with a
water-repellent material; FIG. 7B is a perspective view showing a
state in which a water droplet is put onto a pile of coated
abrasive with abrasive grains of garnet having a grain diameter of
#360 coated with a water-repellent material; and FIG. 7C is a
perspective view showing a state in which a water droplet is put
onto a pile of non-coated abrasive grains of garnet having a grain
diameter of #360;
[0041] FIG. 8 is a perspective view of the essential parts of an
abrasive water jet machining apparatus according to a modification
of the embodiment of the present invention; and
[0042] FIG. 9 is a schematic view of the essential parts of the
abrasive water jet machining apparatus according to the
modification of the embodiment of the present invention.
DETAILED DESCRIPTION
[0043] Hereinafter, an apparatus and method for abrasive water jet
machining according to an embodiment of the present invention will
be described with reference to the accompanying drawings. Before an
explanation of an abrasive water jet machining apparatus 100, a
workpiece W to be used therein will be explained.
<Construction of Workpiece>
[0044] Although the material and shape of the workpiece W is not
particularly limited, a hard-to-machine material, such as glass,
stones, synthetic resin, or composite materials including carbon
fiber reinforced plastic (CFRP), is most suitable as the workpiece
W to be used in the abrasive water jet machining apparatus 100.
Hereinafter, a description will be given using a generally
elongated, substantially planar thick plate as an example of the
workpiece W.
<Construction of Abrasive Water Jet Machining Apparatus>
[0045] As shown in FIG. 1, the abrasive water jet machining
apparatus 100 is a machining apparatus that performs cutting of the
workpiece W by directing an abrasive water jet AWJ with an abrasive
G (an abrasive material G1 or a coated abrasive G3) mixed into
processing fluid Q supplied at a high pressure of 200 to 400 Mpa.
Furthermore, the abrasive water jet machining apparatus 100 can
eject the abrasive water jet AWJ at a high speed equal to or above
the speed of sound, and thus can cut the workpiece W into a shape
of high quality even if the workpiece W is a hard material such as
glass or metal, a relatively soft material such as synthetic resin,
or a composite material composed of various kinds of materials such
as a hard material and a soft material.
[0046] As shown in FIG. 1, the abrasive water jet machining
apparatus 100 is composed mainly of: a nozzle 1 that ejects the
abrasive water jet AWJ mixed with the abrasive G; a high-pressure
water supply device 101 (processing fluid supply portion) that
supplies the processing fluid Q from a high-pressure pipe 102 to
the nozzle 1; an abrasive supply device 8 (abrasive supply portion)
that supplies an appropriate amount of the abrasive G to the nozzle
1; a catcher tank 2 that stores liquid 6; and a liquid level
adjusting device 5 (see FIG. 5) that adjusts a liquid level of the
liquid 6.
[0047] It should be noted that although in this embodiment FIG. 1,
shows the abrasive water jet machining apparatus 100 with an
ejection direction of the abrasive water jet AWJ directed downward,
the present invention is not limited thereto, but also can include
an abrasive water jet machining apparatus that has a nozzle mounted
to a tip of a robot arm capable of freely changing the its
directions, and a portable abrasive water jet machining apparatus
that an operator holds in his/her hand to perform machining.
<Construction of Abrasive>
[0048] As shown in FIG. 2, the abrasive G is abrasive grains to be
mixed into a water jet WJ when machining the workpiece W (see FIG.
1) with the abrasive water jet machining apparatus 100. In the
abrasive water jet machining apparatus 100, two types of abrasives
are used as the abrasive G, as appropriate. The abrasive G to be
used as appropriate includes the following two types of abrasives:
the abrasive material G1 that is the same as that used in the
related art apparatus; and the coated abrasive G3 that is a
water-repellent abrasive or flowable abrasive composed of abrasive
grains in which the abrasive material G1 is coated with a
water-repellent material or a flow promoting material G2. That is,
the abrasive material G1 not subjected to water-repellent
processing or the coated abrasive G3 is used as the abrasive G
according to the kind, intended use, machining conditions of the
workpiece W.
<Construction of Abrasive Material>
[0049] Referring mainly to FIGS. 6A, 6B, and 7A to 7C, the abrasive
material G1, the water-repellent material or flow promoting
material G2, and the coated abrasive G3 composed of a
water-repellent abrasive will be descried.
[0050] As shown in FIG. 6A, the abrasive material G1 is the
abrasive G which is composed of non-coated abrasive grains, the
abrasive grains having a so-called angular shape with acute-angle
corners. As the abrasive material G1, a common material, such as
garnet, sapphire, or a cemented carbide, can be used appropriately
according to the kind or the like of the workpiece W.
[0051] FIG. 7C is a perspective view showing the state at the time
of an experiment in which a droplet of the processing fluid Q (tap
water) supplied from the high-pressure water supply device 101 is
put onto the abrasive material G1 composed of abrasive grains made
of garnet having a grain diameter of #360. As shown in FIG. 7C,
when a drop of water is put on the abrasive material G1, the water
sinks into the abrasive material G1, and therefore the abrasive
material G1 is non-water-repellent and has hydrophilicity.
<Construction of Water-Repellent Material or Flow Promoting
Material>
[0052] The water-repellent material or flow promoting material G2
is a coating material for coating the abrasive material G1 to cause
it to have the function of promoting water repellency or
flowability, and composed of, for example, a fluorine-based
material, silicon-based material, a coating material composed of a
mixture of a fluorine-based material or silicon-based material and
an oily raw material, paraffin, Teflon (R), or an oily raw
material. It should be noted that, more specifically, the
fluorine-based material or silicon-based material includes a common
material, such as fluorine, silicon, and silica, or a compound of a
material, such as fluorine, silicon, and silica, and silane or a
silane derivative. Furthermore, the oily raw material includes
alcohol, ethanol, and various kinds of wax.
[0053] FIG. 7A is a perspective view showing the state at the time
of an experiment in which a droplet of the processing fluid Q (tap
water) used in the high-pressure water supply device 101 is put
onto the coated abrasive G3 composed of a water-repellent abrasive
in which abrasive grains made of garnet having a grain diameter of
#220 are coated with a coating material of 0.2 mass %.
[0054] FIG. 7B is a perspective view showing the state at the time
of an experiment in which a droplet of the processing fluid Q (tap
water) used in the high-pressure water supply device 101 is put
onto the coated abrasive G3 (water-repellent abrasive) in which
abrasive grains made of garnet having a grain diameter of #360 are
coated with a coating material of 0.3 mass %.
[0055] In the experiments shown in FIGS. 7A and 7B, a water droplet
with a large contact angle in the range of 150.degree. to
180.degree. was formed, and therefore it has been confirmed that
the coated abrasive G3 (water-repellent abrasive) has super
water-repellency to strongly repel a water droplet and is hard to
get wet and has small surface tension. It has been also confirmed
that the coated abrasive G3 (water-repellent abrasive) has buoyancy
to float on water when dropped and has a property of floating.
[0056] Furthermore, in an experiment conducted by actually using
the coated abrasive G3 (water-repellent abrasive) in the nozzle 1
as shown in FIGS. 2 and 3, it has been confirmed that, even if the
coated abrasive G3 (water-repellent abrasive) is mixed with the
water jet AW at a high pressure in the range of 200 to 400 MPa,
peeling off of a coating due to the pressure is not caused. That
is, the nozzle 1 has durability in which the water repellency can
be maintained even under a pressure in the range of at least 200 to
400 MPa.
[0057] As shown in FIG. 6B, the coated abrasive G3 (water-repellent
abrasive) is composed of the abrasive grains having a so-called
blocky shape with obtuse angle corners because the whole surface of
the abrasive material G1 is coated with the water-repellent
material (G2). The coated abrasive G3 is inferior in cutting
quality as compared with the abrasive material G1 which is composed
of the unprocessed abrasive grains having the angular shape with
acute-angle corners, but has a property of floating in the
processing fluid Q and water repellency.
[0058] It should be noted that examples of the method for producing
the coated abrasive G3 include, but are not particularly limited
to, a method in which the coated abrasive G3 is produced by putting
the abrasive material G1 and the coating material (water-repellent
material (G2)) into a general mixer, agitating and then drying
them, and a method in which the coated abrasive G3 is produced by
spraying the coating material (water-repellent material (G2)) on
the abrasive material G1 and then drying it. Examples of other
methods for producing the coated abrasive G3 include a method for
producing a metal composite body in which a silica layer made of
silica serving as the water-repellent material (G2) is formed on
surfaces of abrasive grains (metal grains) of the abrasive material
G1 or the like, as disclosed in Japanese Patent Nos. 3906137 and
3906138.
<Construction of Nozzle>
[0059] As shown in FIG. 2, the nozzle 1 includes: a nozzle body 10;
a mixing chamber 13 that is formed within the nozzle body 10; a
water nozzle 14 that is formed with an introducing port 14a to
eject the processing fluid Q (water jet WJ); and an abrasive nozzle
15 that produces the water jet AW mixed with the abrasive G
(hereinafter, simply referred to as the water jet AW) by mixing the
abrasive G (the abrasive material G1 or the coated abrasive G3)
into the water jet WJ ejected from the water nozzle 14 and ejects
the abrasive water jet AWJ for machining the workpiece W.
[0060] It should be noted that in FIG. 2, for example, the
relationship between the diameter of the water nozzle 14 and the
diameter of the water jet WJ is visually simplified for convenience
of explanation, and it is generally assumed that the diameter of
the jet ejected is smaller than the nozzle diameter. Furthermore,
in FIGS. 1 and 2, the grain diameter of the abrasive G (the
abrasive material G1 or the coated abrasive G3) is drawn by
magnifying its size, and there are shown a state in which the
abrasive G flows while floating in air within the mixing chamber 13
and a state in which the abrasive G flows within the abrasive
supply device 8.
[0061] The nozzle body 10 is a member that is composed of an upper
body 11 and a lower body 12 and designed to position with high
accuracy and dispose the components including the water nozzle 14.
The mixing chamber 13 is formed in a central portion of the nozzle
body 10. It should be noted that although in this embodiment, the
nozzle body 10 has a structure separated into the upper body 11 and
the lower body 12, the upper body 11 and the lower body 12 may be
integrated.
[0062] The mixing chamber 13 forms a space of a nearly columnar
shape. In a central portion of the mixing chamber 13, the water jet
WJ ejected from the water nozzle 14 passes through the inside of
the mixing chamber 13 to be introduced into the abrasive nozzle
15.
[0063] The mixing chamber 13 includes a supply port 13a allowing
the abrasive G (the abrasive material G1 or the coated abrasive G3)
to be introduced therein. The abrasive G discharged from the
abrasive supply device 8 (see FIG. 1) is sucked together with air
from the supply port 13a and introduced into the mixing chamber 13.
Thus, the abrasive G introduced into the mixing chamber 13 is mixed
into the water jet WJ to produce the abrasive water jet AWJ mixed
with the abrasive G. The abrasive supply device 8 (see FIG. 1) is
designed to discharge an appropriate amount of the abrasive G to
the supply port 13a.
[0064] Within the mixing chamber 13, the supply port 13a is
disposed toward the introducing port 14a of the water nozzle 14
with respect to an upper end of the abrasive nozzle 15. That is,
the supply port 13a prevents the abrasive G from entering the water
jet WJ and clogging an upstream opening end of the abrasive nozzle
15 within the mixing chamber 13.
[0065] In this manner, when the water jet WJ ejected from the water
nozzle 14 passes through the inside of the mixing chamber 13, an
appropriate amount of the abrasive G (the abrasive material G1 or
the coated abrasive G3) is suitably sucked together with air from
the supply port 13a by a negative pressure generated by the high
speed water jet WJ. Therefore, clogging with the abrasive G near
the supply port 13a can be effectively avoided. Furthermore, the
abrasive G sucked from the supply port 13a is drawn and mixed into
the water jet WJ within the mixing chamber 13 while floating
together with an air current and accumulating to produce the water
jet AW mixed with an appropriate amount of the abrasive material G1
or the coated abrasive G3.
[0066] As shown in FIG. 3, the water nozzle 14 is a member that
includes: a body portion 14b disposed by being embedded in an
upstream portion (upper portion in FIG. 2) of the upper body 11;
and a nozzle portion 14c embedded in the body portion 14b, to
inject, into the mixing chamber 13 from the nozzle portion 14c, the
processing fluid Q supplied from the high-pressure pipe 102 to the
introducing port 14a. Therefore, a hole diameter D1 of the water
nozzle 14 (the nozzle portion 14c) is set smaller than an inner
diameter D3 of the body portion 14b and a hole diameter D2 of the
abrasive nozzle 15.
[0067] As shown in FIG. 3, the abrasive nozzle 15 is installed
within the cylindrical lower body 12. The abrasive nozzle 15 is a
member designed to introduce the water jet AW mixed with the
abrasive G and direct the abrasive water jet AWJ at the workpiece
W.
[0068] Furthermore, the hole diameter D2 of the abrasive nozzle 15
is set, for example, in the range of about 0.2 to 0.7 mm and,
preferably, set larger than the hole diameter D1 of the water
nozzle 14.
[0069] That is, an advantageous effect of preventing clogging of
the abrasive nozzle 15 with the abrasive G can be expected by
setting the hole diameter D2 of the abrasive nozzle 15 to be larger
than the hole diameter D1 of the water nozzle 14.
<Construction of Abrasive Supply Device>
[0070] As shown in FIG. 2, the abrasive supply device 8 (abrasive
supply portion) is a device for supplying, as appropriate, the
abrasive G composed of the abrasive material G1 or the coated
abrasive G3 to the nozzle 1. The abrasive supply device 8 is
composed mainly of: a first abrasive supply device 8A (abrasive
material supply portion) that supplies abrasive grains of the
unprocessed abrasive material G1 to the processing fluid Q in the
nozzle 1; a second abrasive supply device 8B (coated abrasive
supply portion) that supplies abrasive grains of the coated
abrasive G3 to the processing fluid Q in the nozzle 1; a switching
unit 88 for selecting the abrasive G to be supplied to the nozzle 1
between the abrasive material G1 and the coated abrasive G3; and an
abrasive suction pipe 89 that couples the switching unit 88 and the
nozzle 1.
[0071] The first abrasive supply device 8A for supplying the
non-coated abrasive material G1 and the second abrasive supply
device 8B for supplying the coated abrasive G3 have the same
structure. Therefore, the first abrasive supply device 8A will be
mainly described and description of the other device will not be
given accordingly.
[0072] The first abrasive supply device 8A (second abrasive supply
device 8B) includes: an abrasive material supply pipe 80a (coated
abrasive supply pipe 80b) that supplies the abrasive material G1
(coated abrasive G3) stored in an abrasive material supply tank
(not shown); a storage portion 81 that stores the abrasive material
G1 (coated abrasive G3); an outlet hole 82 that is disposed at a
lower portion of the storage portion 81; a carrier rotor 83 that is
disposed below the outlet hole 82 with a predetermined gap .delta.
(see FIG. 4) and driven to rotate around a rotating shaft 83a in a
horizontal direction; a motor 84 that rotationally drives the
carrier rotor 83; a control unit (not shown) that controls the
rotation of the motor 84; a receiving portion 85 that is disposed
below the carrier rotor 83; a discharge port 86 that is formed in
the receiving portion 85; and an abrasive material suction pipe 87A
(coated abrasive suction pipe 87B) that sucks the abrasive material
G1 (coated abrasive G3) discharged from the discharge port 86 by
the negative pressure generated by high-pressure water to supply it
to the nozzle 1.
[0073] As shown in FIG. 4, the carrier rotor 83 includes a
projection portion 83b serving as a projecting-recessed portion
formed at an outer periphery thereof, and a wall portion 83c
circumferentially formed. The projection portion 83b is formed
linearly along an axial direction, and a plurality of the
projection portions 83b are formed at equally spaced
circumferential points like blades of a water wheel. The wall
portion 83c is formed like a flange to project radially from both
edge portions of an outer peripheral portion of the carrier rotor
83.
[0074] With this construction, the carrier rotor 83 is designed to
hold the abrasive material G1 (coated abrasive G3) flowing from the
outlet hole 82 so as to prevent it from being scattered, and carry
a required amount of the abrasive material G1 (coated abrasive G3)
to the receiving portion 85 with proper timing.
[0075] It should be noted that although in this embodiment, the
projection portion 83b is provided at the outer peripheral portion
of the carrier rotor 83, the projection portion 83b is not
particularly limited if it has a shape that allows a predetermined
amount of the abrasive material G1 (coated abrasive G3) to
accumulate therein for a predetermined time, but may include a
recessed portion or may be composed of a recessed portion and a
projecting portion, or may be formed without such recessed and
projecting portions.
[0076] As shown in FIG. 2, the first abrasive supply device 8A
(second abrasive supply device 8B) is a device that causes a
predetermined amount of the abrasive material G1 (coated abrasive
G3) to flow downwardly from the outlet hole 82 disposed at a lower
portion of the storage portion 81 and carries the abrasive material
G1 (coated abrasive G3) from the outlet hole 82 to the receiving
portion 85 with the carrier rotor 83, and supplies the abrasive
material G1 (coated abrasive G3) to the supply port 13a of the
mixing chamber 13 from the discharge port 86 formed in the
receiving portion 85 through the abrasive material suction pipe 87A
(coated abrasive suction pipe 87B), the switching unit 88, and the
abrasive suction pipe 89.
[0077] As shown in FIG. 4A, the first abrasive supply device 8A
(second abrasive supply device 8B) is provided with the
predetermined gap .delta. between the outlet hole 82 and the
carrier rotor 83. Thus, in a state in which the carrier rotor 83 is
stopped, the abrasive material G1 (coated abrasive G3) can be held
in an accumulated state in the predetermined gap .delta. by
frictional resistance among the grains.
[0078] On the other hand, when the carrier rotor 83 is rotated, the
first abrasive supply device 8A (second abrasive supply device 8B)
carries the abrasive material G1 (coated abrasive G3) accumulated
in the gap 8 along an outer peripheral surface of the carrier rotor
83 to thereby cause the subsequent abrasive material G1 (coated
abrasive G3) to flow again into the gap 8 from the outlet hole 82
(see FIG. 4C).
[0079] The switching unit 88 is a switching valve having two input
ports and a single output port, and the input ports may be switched
manually or automatically by electromagnetic force.
[0080] In this manner, as shown in FIG. 1, in response to the
rotation of the carrier rotor 83, the first abrasive supply device
8A (second abrasive supply device 8B) of the abrasive supply device
8 carries the abrasive material G1 (coated abrasive G3) flowing
into the gap .delta. along the outer peripheral surface of the
carrier rotor 83 according to rotational speed of the carrier rotor
83, and receives the abrasive material G1 (coated abrasive G3) in
the receiving portion 85 for the abrasive material G1 (coated
abrasive G3) disposed below the carrier rotor 83, and supplies the
abrasive material G1 (coated abrasive G3) to the supply port 13a of
the mixing chamber 13 from the discharge port 86 formed in the
receiving portion 85.
[0081] The abrasive supply device 8 appropriately controls the
rotational speed of the carrier rotor 83 with the control unit (not
shown), thereby allowing uniform and smooth supply of an
appropriate amount of the abrasive material G1 (coated abrasive G3)
to the mixing chamber 13 with proper timing, or allowing supply of
the abrasive G by causing the switching unit 88 to operate and
automatically select the abrasive material G1 or the coated
abrasive G3 with proper timing according to the workpiece W, or
allowing alternate supply of the abrasive material G1 and the
coated abrasive G3 with proper timing.
<Construction of Catcher Tank>
[0082] As shown in FIG. 5, the catcher tank 2 is a tank that stores
the liquid 6 for receiving abrasive water jet AWJ, with the
workpiece W sunk in the liquid 6. The catcher tank 2 is provided
with: a water level adjusting tank 3 for adjusting a liquid level
of the liquid 6 in the catcher tank 2; a pedestal 4 like a table
for placing and holding the workpiece W; the liquid level adjusting
device 5 that varies a liquid level of the liquid 6 in the catcher
tank 2; a coated abrasive recovery device 7 that recovers the
coated abrasive G3 discharged from an discharge pipe 52; and an
abrasive material recovery device 9 that recovers the abrasive
material G1 contained in the liquid 6 inside the catcher tank
2.
<Construction of Water Level Adjusting Tank>
[0083] The water level adjusting tank 3 is a tank of an inverted
container shape with a bottom opening. The water level adjusting
tank 3 is provided with: an airtight chamber 3a that is formed in a
ceiling portion inside the water level adjusting tank 3; a
partition wall 3b that partitions the water level adjusting tank 3
and the catcher tank 2; a lower trough portion 3c that is formed
below the partition wall 3b to communicate with a region filled
with water inside the catcher tank 2; a pump P1 that leads air into
and out of an upper portion inside the airtight chamber 3a; and a
water level adjusting pipe 51 that is vertically disposed inside
the airtight chamber 3a.
[0084] The airtight chamber 3a is an air pocket formed in the
ceiling portion inside the water level adjusting tank 3 having an
inverted container shape. The amount of air in the airtight chamber
is adjusted by the pump P1 to be described later so that the water
level of the liquid 6 in the water level adjusting tank 3 is
adjusted.
[0085] The partition wall 3b is a wall for partitioning the water
level adjusting tank 3 and the catcher tank 2 and forming the lower
trough portion 3c therebelow so that the water level of the liquid
6 in the water level adjusting tank 3 and the water level of the
liquid 6 in the catcher tank 2 are linked together.
[0086] The lower trough portion 3c is a portion for forming a flow
passage allowing the liquid 6 to flow between the water level
adjusting tank 3 and the catcher tank 2 according to the
fluctuation in the water level of the liquid 6 in the water level
adjusting tank 3.
[0087] The pump P1 is a pump to lower the water level of the liquid
6 in the water level adjusting tank 3, with increases in the air
pressure in the airtight chamber 3a, by sending air into the
airtight chamber 3a and force the liquid 6 into the catcher tank 2
through the lower trough portion 3C to raise the water level of the
liquid 6 in the catcher tank 2. Furthermore, when discharging air
to the inside of the airtight chamber 3a, the pump P1 is designed
to, for example, with the pump P1 in its OFF position, discharge
the air in the airtight chamber 3a to the outside and reduce the
internal air pressure of the airtight chamber 3a to cause the
liquid 6 in the catcher tank 2 to flow into the water level
adjusting tank 3 so as to lower the water level of the catcher tank
2.
[0088] The water level adjusting pipe 51 is a tubular member that
is provided within the water level adjusting tank 3 for water level
adjustment, which constitutes a portion of the liquid level
adjusting device 5 to be described later. The water level adjusting
pipe 51 is designed to adjust the water level so that the water
level matches the thickness of the workpiece W to be cut, by
adjusting its longitudinal position and changing the position of an
opening edge of a lower end thereof. The lower end of the water
level adjusting pipe 51 has an opening at the same level as the
minimum water level in which the water level in the water level
adjusting tank 3 is the lowest, and an upper end of the water level
adjusting pipe 51 penetrates the water level adjusting tank 3 and
has an external opening in an open state.
<Construction of Liquid Level Adjusting Device>
[0089] As shown in FIG. 5, the liquid level adjusting device 5 is a
device that adjusts the liquid level of the liquid 6 by adjusting
heights H1 and H2 of a discharge port 52a provided within the
catcher tank 2. The liquid level adjusting device 5 includes the
water level adjusting pipe 51, and the discharge pipe 52 for
discharging the liquid 6 stored in the catcher tank 2 and the
coated abrasive G3 floating on the liquid surface of the liquid
6.
[0090] The discharge pipe 52 has a lower end 52b turnably
(tiltably) mounted on a side wall of the catcher tank 2, and is
provided so that the discharge port 52a at an upper end thereof can
be displaced with respect to the liquid surface of the liquid 6 by
causing the discharge pipe 52 to pivot about the lower end 52b. The
discharge pipe 52 is composed of a cylindrical overflow pipe that
has: the discharge port 52a formed in the upper opening end; and
the lower end 52b formed by bending in an L-shape and journaled to
the side wall in the vicinity of an inner bottom of the catcher
tank 2.
[0091] The discharge port 52a is an opening for discharging the
liquid 6 and the coated abrasive G3 floating on the liquid 6 to the
outside of the catcher tank 2, and formed by the upper opening of
the discharge pipe 52. In the case where the discharge pipe 52 is
disposed vertically as shown by the solid line in FIG. 5, the
discharge port 52a also serves as an overflow discharge port that
adjusts an upper limit water level for keeping the water level of
the catcher tank 2 to a maximum water level 6a and discharging the
liquid 6 and the coated abrasive G3 exceeding the maximum water
level 6a to the outside of the catcher tank 2. Furthermore, in the
case where the discharge pipe 52 is disposed in a tilted position
as shown by the two-dot chain line in FIG. 5, the discharge port
52a also serves as an overflow discharge port that adjusts the
lower limit water level for, for example, changing the water level
of the catcher tank 2 to a minimum water level 6b and discharging
the liquid 6 and the coated abrasive G3 exceeding the minimum water
level 6b to the outside of the catcher tank 2.
[0092] For example, at the time of cutting the workpiece W using
the coated abrasive G3, when the abrasive water jet AWJ ejected
from the abrasive nozzle 15 shown in FIG. 5 is dropped into the
catcher tank 2, the amount of water in the catcher tank 2
increases, and therefore the water level in the catcher tank 2
exceeds the maximum water level 6a preliminarily set, so that the
liquid 6 and the coated abrasive G3 are discharged from the
discharge port 52a.
[0093] The position of the discharge port 52a (i.e. the water level
of the liquid 6) can be adjusted as appropriate by adjusting a tilt
angle .theta. of the discharge pipe 52 according to the height of
the workpiece W. The excessive liquid 6 in the catcher tank 2 and
the coated abrasive G3 floating on the liquid 6 can be discharged
to the outside of the catcher tank 2 by tilting the discharge pipe
52 and thereby lowering the heights H1 and H2 of the discharge port
52a.
[0094] Furthermore, when air is sent into the airtight chamber 3a
by the pump P1, the water level of the liquid 6 in the catcher tank
2 increases, so that the liquid 6 and the coated abrasive G3
floating on the liquid 6 can be discharged from the discharge port
52a to the outside of the catcher tank 2.
[0095] The coated abrasive recovery device 7 is a separation device
that is disposed below the lower opening end of the discharge pipe
52 to separate and recover the used liquid 6 and coated abrasive G3
discharged from the discharge pipe 52. The coated abrasive recovery
device 7 includes: a separator 71 that separates a turbid liquid
composed of a mixture of the immersion liquid 6 and the coated
abrasive G3 into the immersion liquid 6 and the coated abrasive G3;
an used coated abrasive discharge pipe 72 that supplies the used
coated abrasive G3, etc. discharged from the discharge pipe 52; an
used coated abrasive recovery pipe 73 that receives the used coated
abrasive G3 having undergone the separator 71; and an used liquid
recovery pipe 74 that receives the used liquid 6 having undergone
the separator 71.
[0096] The separator 71 is a device that separates the used liquid
6 and coated abrasive G3 overflowing and entering the discharge
port 52a of the catcher tank 2, into the liquid 6 and the coated
abrasive G3 for recycled use thereof. The separator 71 is, for
example, a centrifugal machine that centrifugally separates the
turbid liquid into the liquid 6 and the coated abrasive G3 by
gravity difference.
[0097] The used coated abrasive discharge pipe 72 is a pipe for
sending, to the separator 71, the turbid liquid composed of a
mixture of the used coated abrasive G3 and liquid 6. The used
coated abrasive discharge pipe 72 is connected to the discharge
pipe 52 at its upstream side and connected to an upper end of the
separator 71 at its downstream side.
[0098] The used coated abrasive recovery pipe 73 is a pipe that is
connected to an upper end of a side surface of the separator 71 at
its upstream side and connected to the coated abrasive supply pipe
80b at its downstream side to return the used coated abrasive G3 to
the coated abrasive supply pipe 80b and circulate it, thereby
enabling recycled use thereof.
[0099] The used liquid recovery pipe 74 is a pipe that is connected
to a lower end of the separator 71 at its upstream side and
connected to the high-pressure water supply device 101 (see FIG. 1)
at its downstream side to return the filtered liquid 6 to the
high-pressure water supply device 101 for recycled use thereof in
the nozzle 1.
[0100] It should be noted that the coated abrasive recovery device
7 may have any structure that can recover the used coated abrasive
G3 in the catcher tank 2, and its structure or the like is not
particularly limited. For example, the coated abrasive recovery
device 7 may include a coated abrasive recovery filter or filtering
device that separates, into the liquid 6 and the coated abrasive
G3, the used liquid 6 and coated abrasive G3 overflowing and
entering the discharge port 52a.
[0101] Furthermore, as shown in FIG. 5, the coated abrasive
recovery device 7 has been described using as an example the case
where the used coated abrasive discharge pipe 72 located at an
upper portion of the separator 71 is coupled to the discharge pipe
52 provided at a side wall of the catcher tank 2. However, a
coupler between the liquid level adjusting device 5 and the coated
abrasive recovery device 7 may be changed as appropriate.
[0102] For example, the coated abrasive recovery device 7 may be
such that the discharge pipe 52 of the liquid level adjusting
device 5 extends directly downward of the catcher tank 2 and
penetrates an inner bottom of the catcher tank 2 to be connected in
communication to the separator 71, thereby recovering the coated
abrasive G3 or the like.
[0103] Alternatively, the coated abrasive recovery device 7 may be
an external device that is installed outside the catcher tank 2,
such as disposing it outside the side wall of the catcher tank
2.
<Construction of Abrasive Material Recovery Device>
[0104] The abrasive material recovery device 9 is a device that
separately recovers the liquid 6, abrasive material G1, and
sludge-like chips in the catcher tank 2 so as to enable recycled
use of the used liquid 6 and abrasive material G1 in the catcher
tank 2. For example, the abrasive material recovery device 9 is a
classifying machine that separates liquid 6, the abrasive material
G1, and chips according to gravity and grain diameter by
centrifugal force. The abrasive material recovery device 9
includes: an abrasive material discharge pipe 91 for recovering the
abrasive material G1 settling at the inner bottom of the catcher
tank 2; a suction pump P2 that is provided in the abrasive material
discharge pipe 91; a classifier 92 that separates the liquid 6,
abrasive material G1, and chips sucked by the suction pump P2; a
chip recovery pipe 93 that receives the chips having undergone the
classifier 92; an abrasive material recovery pipe 94 that receives
the abrasive material G1 having undergone the classifier 92; and an
liquid recovery pipe 95 for discharging the liquid 6 having
undergone the classifier 92.
[0105] As shown in FIG. 5, the abrasive material discharge pipe 91
has a lower opening end disposed in the vicinity of the inner
bottom of the catcher tank 2 and an upper opening end connected to
an upper side surface of the classifier 92.
[0106] The suction pump P2 is a pump that is disposed on the way of
the abrasive material discharge pipe 91 to suck the abrasive
material G1 sinking in the liquid 6 together with the immersion
liquid 6 and send it to the classifier 92. The suction pump P2 is
driven by an electric motor (not shown).
[0107] The chip recovery pipe 93 is a pipe for discharging the
chips having undergone the classifier 92. The chip recovery pipe 93
is connected to a lower end of the classifier 92 at its upstream
side and disposed, for example, on a disposal tank (not shown) at
its downstream side.
[0108] The abrasive material recovery pipe 94 is a pipe for
discharging the abrasive material G1 having undergone the
classifier 92. The abrasive material recovery pipe 94 is connected
to an upper side surface of the classifier 92 at its upstream side
and connected to the abrasive material supply pipe 80a (see FIG. 2)
at its downstream side so as to enable recycled use of the abrasive
material G1.
[0109] The liquid recovery pipe 95 is a pipe for discharging the
liquid 6 having undergone the classifier 92. The liquid recovery
pipe 95 is connected to an upper end of the classifier 92 at its
upstream side and connected to the high-pressure water supply
device 101 (see FIG. 2) at its downstream side so as to enable
recycled use of the liquid 6.
[0110] It should be noted that the abrasive material recovery
device 9 may have any structure that can recover the used abrasive
material G1 in the catcher tank 2, and its structure or the like is
not particularly limited. For example, the abrasive material
recovery device 9 may include an abrasive material recovery filter
or filtering device that recovers the used abrasive material G1
settling at the inner bottom of the catcher tank 2 and separates
the abrasive material G1 from the chips and the liquid 6.
<Construction of Pedestal>
[0111] As shown in FIG. 5, the pedestal 4 is a workpiece supporting
base that receives the workpiece W with a number of thin plates 4a
horizontally arranged in parallel at an appropriate spacing.
[0112] Each of the thin plates 4a, with a plane of a thin
horizontally long flat member in a vertical position, is extended
in a width direction of the catcher tank 2, and a number of the
thin plates 4a are arranged in parallel with slit spaces thereamong
along the liquid surface of the liquid 6 in the catcher tank 2 so
that the workpiece W is placed thereon for underwater cutting.
<Operation>
[0113] Next, referring mainly to the accompanying drawings, an
apparatus and method for abrasive water jet machining according to
the embodiment of the present invention will be described in the
order of an operation process.
[0114] As shown in FIG. 5, before the start of operation, the pump
P1 is in the OFF position. Because the pump P1 is in the OFF
position, air in the airtight chamber 3a is discharged into the
atmosphere from the pump P1, so that the internal pressure of the
airtight chamber 3a is same as atmosphere. Thus, the liquid 6 in
the catcher tank 2 flows into the water level adjusting tank 3, and
the water level of the liquid 6 in the catcher tank 2 is reduced to
a predetermined water level. With the water level in the catcher
tank 2 reduced in this manner, firstly, the workpiece W is mounted
on the pedestal 4 inside the catcher tank 2.
[0115] Next, the pump P1 is switched to the ON position, and the
position of the discharge port 52a is adjusted by setting the
discharge pipe 52 to the desired angle .theta., thereby allowing
machining with the water level of the liquid 6 in the catcher tank
2 at a position lower than the workpiece W or machining with the
water level of the liquid 6 at a position (in water) higher than
the workpiece W. For example, in the case of machining in liquid,
as shown in FIG. 5, with the discharge pipe 52 in a vertical
position, the pump P1 is switched to the ON position, and the water
level of the liquid 6 is set to a position higher than the height
of workpiece W.
[0116] Subsequently, the high-pressure water supply device 101
shown in FIG. 2 is driven to supply the water jet WJ to the nozzle
1, and the abrasive supply device 8 is driven to supply the
abrasive G to the nozzle 1 so that cutting of the workpiece W is
performed by the abrasive water jet AWJ.
[0117] At the time of the cutting, firstly, piercing of the
workpiece W is performed by the low-pressure abrasive water jet
AWJ. Then, after the pressure of the abrasive water jet AWJ is
increased, the cutting is performed starting from a hole formed by
piercing. It should be noted that machining is performed while
adjusting a machining condition in accordance with the material of
the workpiece W because there is a difference in feed speed, tilt
angle, etc. between the case where the workpiece W is glass which
is hard to cut and the case where the workpiece W is a relatively
easy-to-cut material, such as aluminum or stainless steel.
[0118] Furthermore, at the time of machining, either the abrasive
material G1 of the first abrasive supply device 8A or the coated
abrasive G3 of the second abrasive supply device 8B is selected as
appropriate by selecting the switching unit 88 and supplied to the
nozzle 1.
[0119] In this case, agglomeration of the abrasive G in the nozzle
1, etc. or clogging with the abrasive G can be eliminated
especially by selecting the switching unit 88 to the second
abrasive supply device 8B and supplying the coated abrasive G3 to
the nozzle 1. This is because, as shown in FIG. 3, the abrasive
grains of the coated abrasive G3 coated with the water-repellent
material or flow promoting material G2, in liquid, such as in the
water jet AW, repel one another by the super water-repellency and
are stably dispersed without approaching one another or
agglomerating, and also can promote the flowability of the abrasive
material G1.
[0120] Furthermore, at the time of cutting the workpiece W, the
abrasive material G1 is composed of abrasive grains having an
angular shape with acute-angle corners and superior in cutting
quality as compared with the abrasive grains of the coated abrasive
G3.
[0121] Thus, at the time of machining with the abrasive water jet
machining apparatus 100, cutting is performed while selecting the
abrasive G between the abrasive material G1 and the coated abrasive
G3 or alternately supplying the abrasive material G1 and the coated
abrasive G3 with proper timing by switching the switching unit 88
of the abrasive supply device 8 as appropriate according to a
machining condition, such as the shape, material, thickness, or
finishing of the workpiece W. Thus, even if the abrasive material
G1 agglomerates, the abrasive material G1 can be dispersed
separately and stabilized by the action of the super
water-repellency of the coated abrasive G3.
[0122] As shown in FIG. 5, the coated abrasive G3 ejecting from the
nozzle 15 into the catcher tank 2 floats on a liquid surface of the
liquid 6 in the catcher tank 2 and overflows and enters the
discharge pipe 52 to be separated by the coated abrasive recovery
device 7 so that it can be recycled, and then is recirculated into
the coated abrasive supply pipe 80b of the second abrasive supply
device 8B.
[0123] Furthermore, the abrasive material G1 ejecting from the
nozzle and chips falling into the catcher tank 2 by cutting sinks
to the inner bottom of the catcher tank 2 and is sucked into the
abrasive material discharge pipe 91 by the suction pump P2 to be
separated by the abrasive material recovery device 9 so that it can
be recycled, and then is recirculated into the abrasive material
supply pipe 80a of the first abrasive supply device 8A, and the
chips are discarded through the chip recovery pipe 93.
[0124] It should be noted that the abrasive material G1 and chips
sinking to the inner bottom of the catcher tank 2 may be recovered
from the catcher tank 2 by the abrasive material recovery device 9
or the like and then discarded without being recycled.
[0125] After the machining of the workpiece W is finished, the pump
P1 is turned OFF to cause the air in the airtight chamber 3a to be
discharged to the outside, and the water in the catcher tank 2 with
the water level raised by the machining is moved by its own weight
to the water level adjusting tank 3 with the water level lowered,
thereby lowering the water level in the catcher tank 2. In this
state, the machined workpiece W is removed from the pedestal 4
located inside the catcher tank 2, and machining work is
completed.
<Modification>
[0126] It should be noted that the present invention is not limited
to the above-described embodiment, and various modifications and
changes may be made without departing from the technical idea of
the present invention. The present invention, of course, also
extends to alternative embodiments which incorporate these
modifications and changes, and a modification will be described
referring mainly to FIGS. 8 to 10. It should be noted that the same
elements as those already described are designated by the same
reference signs and a description thereof will not be repeated.
[0127] FIG. 8 is a perspective view of the essential parts of an
abrasive water jet machining apparatus according to a modification
of the embodiment of the present invention. FIG. 9 is a schematic
view of the essential parts of the abrasive water jet machining
apparatus according to the modification of the embodiment of the
present invention.
[0128] In the above-described embodiment, as an example of the
abrasive water jet machining apparatus 100, as shown in FIG. 2, the
abrasive supply device 8 (abrasive supply portion) for supplying
the coated abrasive G3 coated with the water-repellent material or
flow promoting material G2 to the nozzle 1 has been described.
However, the present invention is not limited thereto. For example,
as shown in FIGS. 8 and 9, an abrasive water jet machining
apparatus 100' may include a liquid supply portion 8C that supplies
the water-repellent material or flow promoting material G2 to the
processing fluid Q or the abrasive G.
[0129] In this case, the liquid supply portion 8C is composed of a
device that supplies, to the nozzle 1 supplied with the processing
fluid Q and the abrasive G, the water-repellent material or flow
promoting material G2 composed of any one of liquids of a
fluorine-based material, silicon-based material, a coating material
composed of a mixture of a fluorine-based material or silicon-based
material and an oily raw material, paraffin, and fats. The liquid
supply portion 8C includes: a liquid supply pipe 80c that supplies
the water-repellent material or flow promoting material G2 stored
in a storage tank not shown; a storage portion 81C that is composed
of a tank temporarily storing the water-repellent material or flow
promoting material G2 and having a discharge port 86C; and a liquid
suction pipe 87C that couples the storage portion 81C and the
switching unit 88.
[0130] For example, in order to supply the water-repellent material
or flow promoting material G2 to the processing fluid Q supplied
from the high-pressure pipe 102 to the nozzle 1, the switching unit
88 is switched so that the water-repellent material or flow
promoting material G2 flows from the storage portion 81C to the
nozzle 1, and the supply of the abrasive G from the abrasive
material suction pipe 87A is stopped. Thus, the processing fluid Q
and the water-repellent material or flow promoting material G2 can
be supplied to the nozzle 1 and mixed together.
[0131] Furthermore, in order to supply the abrasive G and the
water-repellent material or flow promoting material G2 to the
nozzle 1, the high-pressure water supply device 101 is stopped to
stop the supply of the processing fluid Q, and the switching unit
88 is switched so as to enable the supply from both the abrasive
material suction pipe 87A and the liquid suction pipe 87C. Thus,
the abrasive G is supplied to the abrasive suction pipe 89 from the
abrasive material suction pipe 87A through the switching unit 88,
and the water-repellent material or flow promoting material G2 is
supplied to the abrasive suction pipe 89 from the liquid suction
pipe 87C through the switching unit 88, so that the abrasive G and
the water-repellent material or flow promoting material G2 are
mixed to be supplied to the nozzle 1.
[0132] In this manner, the water-repellent material or flow
promoting material G2 in the liquid supply portion 8C is supplied
to the nozzle 1 to be mixed into the processing liquid Q or
abrasive G, thereby improving the flowability of the processing
liquid Q or abrasive G with the water-repellent material or flow
promoting material G2 so that it can smoothly flow through the
nozzle 1.
<Another Modification>
[0133] For example, although in the above-described embodiment, the
description has been made using, as an example, the abrasive supply
device 8 which includes the first abrasive supply device 8A and the
second abrasive supply device 8B, the arrangement may be such that
the abrasive supply device 8 includes only the second abrasive
supply device 8B to supply only the coated abrasive G3 to the
nozzle 1.
[0134] Furthermore, in the above-described embodiment, the case
where the supply port 13a is provided at one place of the mixing
chamber 13 has been described. However, the supply port 13a may be
provided at a plurality of places, and a plurality of the abrasive
supply devices 8 may be provided corresponding to the plurality of
supply ports 13a.
EXAMPLES
[0135] Next, referring mainly to tables 1 and 2, examples will be
described.
[0136] In the examples, two kinds of related art abrasive materials
with different grain sizes and the coated abrasive G3
(water-repellent abrasive) of the present invention are supplied to
the nozzles 1 having two different nozzle diameters, and it has
been confirmed that the coated abrasive G3 (water-repellent
abrasive) has the function of eliminating clogging.
TABLE-US-00001 TABLE 1 Experimental Result 1 (in case of nozzle
with inner diameter of .phi.0.5 mm) Abrasive grain Abrasive grain
Abrasive grain Abrasive grain Abrasive grain Abrasive grain
Abrasive grain Abrasive grain ejection ejection ejection ejection
ejection ejection ejection ejection amount: amount: amount: amount:
amount: amount: amount: amount: 20 (g/min) 40 (g/min) 60 (g/min) 80
(g/min) 100 (g/min) 120 (g/min) 140 (g/min) 160 (g/min) Related art
Good Good Good Good Good Good Good Good abrasive material with
grain size of #120 Related art Good Good Good Good Good Good Good
Good abrasive material with grain size of #220 Water-repellent Good
Good Good Good Good Good Good Good abrasive of present invention
with grain size of #220
[0137] Table 1 shows a result of a first experiment in which, using
the abrasive water jet machining apparatus 100 according to the
embodiment of the present invention, each of a related art abrasive
material with a grain size of #120, a related art abrasive material
with a grain size of #220, and the coated abrasive G3
(water-repellent abrasive) of the present invention with a grain
size of #220 is supplied to the nozzle 1 having the abrasive nozzle
15 with a pressure of 300 MPa and an inner diameter of .phi.0.5 mm.
The result is represented as "Good" if the abrasive G is not
agglomerated, as "Fair" if the abrasive G is slightly agglomerated
but does not cause clogging, as "Poor" if the abrasive G is
agglomerated and causes clogging.
[0138] As shown in Table 1, in the case of the abrasive nozzle 15
with an inner diameter of .phi.0.5 mm, as for any of the related
art abrasive material with a grain size of #120, the related art
abrasive material with a grain size of #220, and the coated
abrasive G3 (water-repellent abrasive) of the present invention
with a grain size of #220, agglomeration of the abrasive G and
clogging did not occur. Consequently, all the results were
"Good"
TABLE-US-00002 TABLE 2 Experimental Result 2 (in case of nozzle
with inner diameter of .phi.0.3 mm) Abrasive grain Abrasive grain
Abrasive grain Abrasive grain Abrasive grain Abrasive grain
Abrasive grain Abrasive grain ejection ejection ejection ejection
ejection ejection ejection ejection amount: amount: amount: amount:
amount: amount: amount: amount: 20 (g/min) 40 (g/min) 60 (g/min) 80
(g/min) 100 (g/min) 120 (g/min) 140 (g/min) 160 (g/min) Related art
Good Fair Poor Poor Poor Poor Poor Poor abrasive material with
grain size of #120 Related art Poor Poor Poor Poor Poor Poor Poor
Poor abrasive material with grain size of #220 Water-repellent Good
Good Good Good Good Good Good Good abrasive of present invention
with grain size of #220
[0139] Table 2 shows a result of a second experiment in which,
using the abrasive water jet machining apparatus 100 according to
the embodiment of the present invention, each of a related art
abrasive material with a grain size of #120, a related art abrasive
material with a grain size of #220, and the coated abrasive G3
(water-repellent abrasive) of the present invention with a grain
size of #220 is supplied to the nozzle 1 having the abrasive nozzle
15 with a pressure of 300 MPa and an inner diameter of .phi.0.3
mm.
[0140] As shown in Table 2, in the case of the abrasive nozzle 15
with an inner diameter of .phi.0.3 mm, as for both the related art
abrasive material with a grain size of #120 and the related art
abrasive material with a grain size of #220, clogging occurred
entirely, except that the related art abrasive material with a
grain size of #120 did not cause clogging when the abrasive grain
ejection amount is 20 and 40 (g/min).
[0141] On the other hand, as for the coated abrasive G3
(water-repellent abrasive) of the present invention with a grain
size of #220, it has been confirmed that, in any case, the abrasive
G does not agglomerate and the inside of the nozzle 1 is not
clogged.
* * * * *