U.S. patent application number 13/655641 was filed with the patent office on 2013-02-14 for system for adjusting load characteristics of conical spring.
This patent application is currently assigned to ORII & MEC CORPORATION. The applicant listed for this patent is ORII & MEC CORPORATION. Invention is credited to Hiroshi Ookubo, Osamu Shimomura.
Application Number | 20130036783 13/655641 |
Document ID | / |
Family ID | 44833813 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130036783 |
Kind Code |
A1 |
Ookubo; Hiroshi ; et
al. |
February 14, 2013 |
SYSTEM FOR ADJUSTING LOAD CHARACTERISTICS OF CONICAL SPRING
Abstract
A load characteristic adjustment system for use with a
linear-spring forming apparatus is provided, in which the load
characteristic of a conic spring can be conveniently and
efficiently regulated during the formation of the spring, thereby
reliving much of a physical burden of a worker to find an optimum
load characteristic of a coil spring. The load characteristics
adjustment system comprises: a linear material feeder for feeding a
linear material; at least one spring forming tool facing the linear
material feeder, adapted to abut against the linear material to
coil the linear material; spiraling means for spiraling the coiled
linear material; and coil-diameter varying means for varying the
diameter of the coiled linear material. The load characteristic
adjustment system controls the linear material feeder so as to feed
the linear material at a regulated constant acceleration to adjust
the load characteristic of the conical spring formed.
Inventors: |
Ookubo; Hiroshi;
(Isehara-shi, JP) ; Shimomura; Osamu;
(Isehara-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ORII & MEC CORPORATION; |
Isehara-shi |
|
JP |
|
|
Assignee: |
ORII & MEC CORPORATION
Isehara-shi
JP
|
Family ID: |
44833813 |
Appl. No.: |
13/655641 |
Filed: |
October 19, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2010/056931 |
Apr 19, 2010 |
|
|
|
13655641 |
|
|
|
|
Current U.S.
Class: |
72/138 ;
72/135 |
Current CPC
Class: |
B21F 35/00 20130101;
B21F 3/10 20130101; B21F 23/00 20130101; B21F 3/02 20130101 |
Class at
Publication: |
72/138 ;
72/135 |
International
Class: |
B21F 23/00 20060101
B21F023/00; B21F 3/02 20060101 B21F003/02 |
Claims
1. A load characteristic adjustment system for use with a spring
forming apparatus that includes: a linear material feeder for
feeding therefrom a linear material in the axial direction of the
linear material; at least one spring forming tool arranged to face
the linear material feeder and adapted to be abutted against the
linear material to coil the linear material; spiraling means for
configuring the coiled linear material into a spiral form; and coil
diameter varying means for gradually changing the diameter of the
coiled linear material by dynamically changing the distance between
the spring forming tool and the linear material feeder in
operation, the load characteristic regulating system is
characterized in that the system is adapted to cause the linear
material feeder to feed the linear material at a regulated constant
acceleration to adjust the load characteristic of the conical
spring formed.
2. The load characteristic adjustment system for use with a conical
spring forming apparatus that includes: a linear material feeder
for feeding therefrom a linear material in the axial direction of
the linear material; at least one spring forming tool, arranged to
face the linear material feeder and adapted to be abutted against
the linear material to spiral the linear material; a pitch tool
serving as a spiraling means for spiraling the linear material; and
coil diameter varying means for gradually varying the coil diameter
of the linear material by dynamically varying the distance between
the spring forming tool and the linear material feeder in
operation, the load characteristic regulating system is
characterized in that the system is adapted to cause said means for
gradually varying the coil diameter of the linear material to move,
at a regulated constant acceleration, at least one of the linear
material feeder feeding the linear material and the spring forming
tool to adjust the load characteristic of the conical spring
formed.
3. The load characteristic adjustment system defined in claim 3 is
adapted for use with a conical spring forming apparatus that
includes; a linear material feeder for feeding therefrom a linear
material in the axial direction of the linear material; at least
one spring forming tool, arranged to face the linear material
feeder and adapted to be abutted against the linear material to
spiral the linear material; a pitch tool serving as a spiraling
means for spiraling the linear material; and coil diameter varying
means for gradually varying the diameter of the spiraled linear
material by dynamically changing the distance between the spring
forming tool and the linear material feeder in operation, the load
characteristic regulating system is characterized in that: the
system is adapted to force and move the linear material in the coil
forming direction so as to spiral the linear material at a pitch in
accord with the displacement of the spiraling means; and the system
is adapted to move the pitch tool at a regulated constant
acceleration to gradually varies the spiral pitch, thereby
regulating the load characteristic of the conical spring formed.
Description
TECHNICAL FIELD OF INVENTION
[0001] This invention relates to a system for adjusting the load
characteristic of a conical spring (hereinafter referred to as load
characteristic adjustment system) formed by a linear spring forming
apparatus in a process of coiling a linear material into a conical
spring by abutting a spring forming tool against the linear
material
[0002] An apparatus for coiling a linear material to form a linear
spring is disclosed in Patent Document 1 (JPA Laid Open
2004-237352). In this apparatus the linear material is forcibly fed
from a quill to a spring forming stage, where the linear material
is abutted against a coil forming tool and coiled by the coil
forming tool carried forward to the spring forming stage
perpendicularly to the axis of the linear material.
[0003] The diameter of the coil to be formed (hereinafter referred
to as coil diameter) depends on the distance between the spring
forming tool and the quill. That is, the shorter the distance, the
smaller is the coil diameter, and the larger the distance, the
larger is the coil diameter. Thus, if the coil forming tool is
abutted against the linear material fed from the quill while moving
the quill towards (or away from) the axis of the linear material at
a constant speed perpendicularly to the axis by means of a quill
moving means, the coil diameter can be gradually varied
(increased), thereby resulting in a conical spring.
[0004] However, mainly due to manufacturing fluctuations in
diameter of linear materials, it is often the case that the conical
springs have a fluctuating load characteristic that depends on a
particular manufacture lot. As a consequence, it is likely that
conical springs formed from linear materials of different lots have
fluctuating load characteristics beyond a permissible range if the
apparatus is designed to form the conical springs of the same
configuration. To obtain conical springs having the same load
characteristic, it is therefore necessary to regulate the load
characteristics of conical springs, depending on the manufacturing
lot of the linear material used.
[0005] This can be done by delicately regulating the resultant
shapes of conical springs to have a required load characteristic.
For example, the load characteristic of a spring can be slightly
changed if the inclination of the generatrix of the spring with
respect to the spring axis (that is, the increasing rate of the
coil diameter in the axial direction) is varied. The inclination of
the generatrix varies between conical springs having different
shapes, for example, substantial Mt. Fuji shaped (which is shaped
like a bell of a horn, and hereinafter referred to as bell shaped),
tapered shaped, and bowl shaped ones as shown in FIG. 7(b), by
setting some of the control parameters of the spring forming
apparatus to different magnitudes as shown in FIG. 7(a).
[0006] For example, the spring forming apparatus may be set up in
such a way that the speed of the quill is constant while the
feeding speed (or feed rate) of the linear material fed from the
quill is varied once during spring formation.
[0007] FIG. 7 illustrates relationships between different feed
rates of conical spring forming apparatus (FIG. 7(a) and
corresponding resultant shapes of conical springs (FIG. 7(b). The
upper left and right diagrams of FIG. 7(a) respectively show the
length X and feed rate V of linear material fed from the quill as a
function of feeding time t. Symbol t1 represents time at which the
feed rate is varied, and t2 the total feeding time. The lower left
diagram of FIG. 7(a) indicates the amount of move P (or position)
of the quill as a function of time t (which is equal to the feeding
time t).
[0008] As stated above, the spring forming apparatus is set such
that the quill is moved at a constant speed away from the spring
forming tool between P1 and P3. Further, the spring forming
apparatus is set to feed the linear material from the quill at two
different constant feed rates, as shown in the upper right diagram
of FIG. 7(a).
[0009] Obviously, the circumferential length of a conical spring
becomes larger towards the end of coil than that at the beginning.
As a result, when the linear material is fed at constant feed rate
V0 from the quill moving at constant speed from P1 to P3 as shown
by a double dotted line in the upper right diagram of FIG. 7(a),
the displacement of the quill per one revolution of the coiled
linear material gradually increases towards the end of the spring,
since the feed rate of the linear material is constant but the
circumferential length of the conical spring gradually increases
from the beginning to the end of the spring, as shown in the left
diagram of FIG. 7(b). Thus, the inclination of the generatrix of
the conic spring with respect to the axis L0 thereof becomes
steeper towards the end of the spring than at the beginning, as
shown in the left diagram of FIG. 7(b). In other words, the
inclination of the generatrix of the conical spring with respect to
the axis L0 is less steeper in the first half domain in which the
quill moves from P1 to P2 than in the second half domain in which
the quill moves from P2 to P3, as shown in FIG. 7(b). As a
consequence, the conical spring has a configuration which looks
like a bell of a horn having a concave generatrix. (The
configuration hereinafter referred to as bell type
configuration.)
[0010] It is noted that the inclination of the generatrix becomes
less steeper if the feed rate (feed rate) of the linear material is
increased, and vise versa. Thus, if the feed rate of the linear
material is set to a predetermined speed V1 lower than a
predetermined constant speed V0 in the first half domain (0-t1 in
time) and set to another predetermined speed V2 higher than V0 in
the second half domain (t1-t2 in time) as indicated by solid lines
in the upper right diagram of FIG. 7(a), the inclination of the
generatrix becomes steeper in the first half domain, but less
steeper in the second half domain as shown in the central diagram
of FIG. 7(b), as compared with the shape shown in the left diagram
of FIG. 7(b). As a consequence, the resultant conical spring is
slightly changed in configuration from bell type shown in the left
diagram of FIG. 7(b) to one (hereinafter referred to as tapered
type configuration) having a substantially constant inclination as
shown in the central diagram of FIG. 7(b). Thus, the load
characteristic is slightly changed.
[0011] On the other hand, if the feed rate is set to V3 which is
still lower than V1 in the first half domain (0-t1) and set to V4
higher than V2 in the second half domain (t1-t2) as shown by a
dotted line in the upper right diagram of FIG. 7(a), the
inclination of the generatrix becomes much steeper in the first
half domain than in the second half domain as shown in the right
diagram of FIG. 7(b), as compared with the one shown in the central
diagram. Accordingly, the resultant conical spring looks like a
slightly bulging bowl, as compared with the tapered one (this type
of configuration will be referred to as bowl type configuration),
so that its load characteristic is slightly changed still more than
that of the tapered type.
[0012] As stated above, in the conventional conical spring
formation, fine adjustment of load characteristics is made in such
a way that a parameter "a" associated with the constant feed rate
assumed in a first half domain from t=0 to t=t1 in which the quill
is moved from P1 to P2 and a parameter "b" associated with the
constant feed rate in a second half domain from t=t1 to t=t2 in
which the quill is moved from P2 to P3 are set up in the spring
forming apparatus by a worker, and trial conical springs made under
different values of "a" and "b" having slightly different
configurations that range from bell type to bowl type are tested
until a conical spring having a preferred load characteristic is
obtained.
PRIOR ART DOCUMENT
Patent Document
[0013] Patent Document 1: JPA Laid Open 2004-237352
SUMMARY OF THE INVENTION
Objects of the Invention
[0014] To form a conical spring in a conventional approach, a
worker must repeatedly change constant feed rate parameters ("a"
and "b") until a preferred load characteristic is obtained. Thus,
he must spend much energy and time to find an optimum set of
constant feed rate parameters ("a" and "b"), since there are a
large number of possible combinations of "a" and "b" to test.
[0015] Therefore, operations to determine such optimum set of "a"
and "b" for a given linear material having a particular material
characteristic is hopefully as simple as possible so that the
operations can be done in a short time. In this connection, the
inventors of the present invention came up with an idea that a
great amount of time and repetitive work for forming conical
springs can be reduced if a load characteristic of a conical spring
can be adjusted using less number of control parameters while
making trial conical springs of different shapes as usual.
[0016] In view of the problem stated above, the present invention
is directed to a load characteristic adjustment system for use with
a spring forming apparatus, the load characteristic adjustment
system capable of greatly reducing an amount of work and time
conventionally required in setting up an optimum condition of the
apparatus by reducing the number of control parameters (constant
speed parameters "a" and "b" in conventional system) in the process
of testing a multiplicity of trial conical springs having slightly
different shapes and load characteristics.
Means for Solving the Problems
[0017] To solve the problems above, there is provided in accordance
with claim 1 a load characteristic adjustment system for use with a
spring forming apparatus that includes: a linear material feeder
for feeding a linear material in the axial direction of the linear
material; at least one spring forming tool arranged to face the
linear material feeder and adapted to coil the linear material when
abutted against the linear material; spiraling means for
configuring the coiled linear material into a spiral form; and coil
diameter varying means for gradually changing the diameter of the
coiled linear material by dynamically changing the distance between
the spring forming tool and the linear material feeder in
operation. The load characteristic adjustment system is adapted to
cause the linear material feeder to feed the linear material at a
regulated constant acceleration to adjust the load characteristic
of the conical spring formed.
[0018] (Function) By controlling the feed rate of the linear
material, a multiplicity of conical springs different in shape and
load characteristic can be formed.
[0019] Conventionally, shapes of conical springs and load
characteristics of conical springs, including bell-type,
tapered-type, and bowl-type springs, are controlled by a worker by
varying values of combinatory control parameters ("a" and "b" for
example) to be set up in the spring forming apparatus, associated
with the linear material feed rates. To obtain an optimum
combination of feed rates, however, this task requires great work
and time, since there are a very large number of possible
combinations.
[0020] However, according to the invention as recited in claim 1,
the load characteristic adjustment system can similarly regulate
the configuration of a spiral spring (including bell-type,
tapered-type, and bowl-type ones), and hence the load
characteristic, by simply varying the acceleration of the linear
material fed from the linear material feeder (the acceleration
hereinafter referred to as feeding acceleration), instead of
varying constant feed rates.
[0021] In other words, the load characteristic adjustment system of
claim 1 controls only one control parameter, that is, feeding
acceleration, to vary the configuration and load characteristic of
the spiral spring formed by the spring forming apparatus. As a
result, the inventive load characteristic adjustment system can
obtain a desired spring configuration with less number of trials,
as compared with conventional ones requiring trials as many as the
second power of the number of control parameters. Thus, in this
invention, the amount of work and time needed to obtain an optimum
value of the parameter (feeding acceleration in the present
invention) for a given linear material is greatly reduced.
[0022] The load characteristic adjustment system defined in claim 2
is adapted for use with a conical spring forming apparatus that
includes: a linear material feeder for feeding a linear material in
the axial direction of the linear material; at least one spring
forming tool arranged to face the linear material feeder and
adapted to coil the linear material when abutted against the linear
material; a pitch tool serving as a spiraling means for spiraling
the linear material; and coil diameter varying means for gradually
varying the coil diameter of the coiled linear material by
dynamically varying the distance between the spring forming tool
and the linear material feeder in operation. The load
characteristic adjustment system is adapted to cause said means for
gradually varying the coil diameter to move at a regulated constant
acceleration at least one of the linear material feeder feeding the
linear material and the spring forming tool to adjust the load
characteristic of the conical spring formed.
[0023] (Function) Instead of regulating the feeding acceleration by
the load characteristic adjustment system according to claim 1, the
configuration, and hence the load characteristic, of a conical
spring, may be regulated by the load characteristic adjustment
system according to claim 2 adapted to move at a regulated constant
acceleration at least one of the linear material feeder and the
spring forming tool so as to change the distance between them.
[0024] In other words, the acceleration for moving either the
linear material feeder or the spring forming tool is the only
control parameter needed for the load characteristic adjustment
system to vary the configuration of a conical spring worked out by
the spring forming apparatus, so that the load characteristic
adjustment system enables the conical spring to have a desired
configuration (and load characteristic) with less number of trials
than conventional systems. Thus, the amount of work and time needed
to find an optimum value of the control parameter (constant
acceleration) for a given linear material is greatly reduced.
[0025] The load characteristic adjustment system defined in claim 3
is adapted for use with a conical spring forming apparatus that
includes: a linear material feeder for feeding a linear material in
the axial direction of the linear material; at least one spring
forming tool arranged to face the linear material feeder and
adapted to coil the linear material when abutted against the linear
material; a pitch tool serving as a spiraling means for spiraling
the linear material; and coil diameter varying means for gradually
varying the diameter of the coiled linear material by dynamically
changing the distance between the spring forming tool and the
linear material feeder in operation. The load characteristic
adjustment system is characterized in that:
[0026] the system is adapted to forcibly move the linear material
in the direction of forming the conical spring (the direction
hereinafter referred to as coil forming direction) so as to spiral
the linear material at a given pitch in accord with the
displacement of the spiraling means; and
[0027] the system is adapted to move the pitch tool at a regulated
constant acceleration to gradually vary the pitch of the spiral,
thereby adjusting the load characteristic of the conical spring
formed.
[0028] (Function) The load characteristic of a conical spring can
be adjusted by varying the pitch of the spring. The load
characteristic adjustment system defined in claim 3 is adapted to
cause the pitch tool to move at a regulated constant acceleration
in the coil forming direction to gradually vary the pitch of the
spiral, thereby varying the resultant shape, and hence the load
characteristic, of the spring.
[0029] In other words, this load characteristic adjustment system
regulates only the acceleration of the pitch tool as the control
parameter for varying the shape of a resultant conical spring,
requiring a fewer trials than ever in obtaining the same spring
configuration as obtained by conventional adjustment system which
requires trials as many as the second power of the number of
control parameters. Thus, a number of trials and an amount of work
required in conventional system to obtain optimum values of control
parameters are greatly reduced.
Results of the Invention
[0030] The load characteristic adjustment system of the invention
requires only one parameter, instead of two or more than two
parameters, for controlling the spring forming apparatus in the
process of varying the shape of a conical spring, which means that
the number of trials and time required of a worker to get an
optimum value of the control parameter is not only simplified but
also greatly reduced, thereby relieving the burden of the
worker.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a front view of a coiling machine for use in the
invention.
[0032] FIG. 2 is a front view of a point tool unit in accordance
with a first embodiment of the invention.
[0033] FIG. 3 is a perspective view of the point tool unit of FIG.
2, as viewed from the rear end thereof.
[0034] FIG. 4 is an enlarged perspective view of a linear material
feeder near the point tool of the point tool unit.
[0035] FIG. 5 is an enlarged front view of the linear material
feeder near the point tool of FIG. 4.
[0036] FIG. 6 is a plan view of the linear material feeder near the
point tool, showing the coiling machine of the first embodiment in
the process of forming a conical spring.
[0037] FIG. 7(a) shows diagrams illustrating how the material is
fed from a prior art linear material feeder and how the movement of
the feeder is controlled.
[0038] FIG. 7(b) shows resultant configurations of conical springs
formed under the controlled conditions shown in FIG. 7(a).
[0039] FIG. 8(a) shows diagrams illustrating how the material is
fed from an inventive linear material feeder and how the movement
of the feeder is controlled.
[0040] FIG. 8(b) shows resultant configurations of conical springs
under the controlled conditions shown in FIG. 8(a).
[0041] FIG. 9 is a front view, partially shown in cross section, of
a coil spring forming apparatus in accordance with a second
embodiment of the invention.
[0042] FIG. 10 is an enlarged cross section of the coil spring
forming tool shown in FIG. 9.
[0043] FIG. 11(a) shows positions of a right- and a left-handed
coil spring forming tool mounted on a tool holder.
[0044] FIG. 11(b) shows the right-handed coil spring forming tool
as viewed from the direction II of FIG. 11(a).
[0045] FIG. 11(c) shows the left-handed coil spring forming tool as
viewed from the direction III of FIG. 11(a).
[0046] FIG. 12 is a plan view of a quill near the coil spring
forming tool, showing how a conical spring is formed by the spring
forming apparatus in accordance with the second embodiment of the
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0047] The coiling machine in accordance with a first embodiment of
the invention will now be described in detail by way of example
with reference to FIGS. 1 through 5.
[0048] This coiling machine (linear spring forming apparatus) 150
has a linear material feeding unit 151 for feeding a linear
material 1 to a spring forming stage 200, a point tool unit 152 to
be abutted against the linear material 1 to forcibly bend the
linear material 1 fed from the linear material feeding unit 151, a
cored bar 153 for guiding the bent linear material 1, a pitch tool
154 for spiraling the linear material 1 into a coil by pressing the
bent linear material 1 in the coil forming direction, and a cutting
unit 155 for cutting the linear material 1 at the end of the
coil.
[0049] The linear material feeding unit 151 includes a linear
material guide 156 having a guide groove 156a for guiding the
linear material 1 along the axis X1 of the linear material 1, a
pair of feed rollers (157a and 157b) for rotating the linear
material 1 fixedly held on the linear material guide 156 towards
the leading end of the linear material guide 156 (in the direction
D1 of FIG. 1) by means of a feed motor (not shown), and a linear
material feeder 158 for feeding the linear material to the spring
forming stage 200 provided at the leading end of the linear
material guide 156.
[0050] The point tool unit 152 has a point tool 160 having an
abutting groove 159 for receiving therein in abutting condition the
linear material 1 fed from the linear material feeder 158 to bend
the linear material, a slide table 161 having on the surface
thereof the point tool 160, and coil diameter regulation means 162
for dynamically regulating the distance between the leading end of
the point tool 160 and the linear material feeder 158 by moving the
slide table 161 in the axial direction X1 of the linear material.
The leading end of the point tool 160 is arranged in opposition to
the linear material feeder 158.
[0051] The cored bar 153 arranged between the linear material
feeder 158 and the abutting groove 159 extends in the coil forming
direction (CF direction as indicated in FIG. 4) and along line X2
(which is the axis of the coil shown in FIG. 6) perpendicular to
the axis X1. The cored bar 153 has a semi-circular cross section,
with its arcuate periphery facing the abutting groove 159 to guide
the bent linear material 1 to the pitch tool 154.
[0052] The coil diameter of a coil formed increases in proportion
to the distance between the linear material feeder 158 and the
abutting groove 159. This distance can be regulated by coil
diameter regulation means 162 adapted to move the point tool 160
towards or away from the linear material feeder 158.
[0053] The coil diameter regulation means 162 has a pair of slide
rail units 163 securely fixed to the coiling machine 150 at a
predetermined position with bolts 163f, for example, for holding
the slide table 161 slidable in the axial direction X1 of the
linear material, a cam receiving member 164 provided on the
backside of the slide table 161, a cam member 165 rotated by a cam
motor (not shown) to move the point tool 160 mounted on the slide
table 161 in one direction along the axial direction X1 of the
linear material by pushing the periphery of the cam receiving
member 164, and a spring member 166 for urging a cam member 165 in
the direction opposite to the moving direction of the cam member
165, thereby urging the slide table 161 in that opposite
direction.
[0054] The slide rail unit 163 is provided on the upper and lower
ends thereof with slide rails (163a and 163b), and at the rear end
thereof with a mount 163c for mounting the spring member 166 and a
stopper 163d. The slide table 161 is held by the slide rails 163a
and 163b from above and below, respectively, and can slide either
in TF direction (which is the feeding direction of the linear
material feeder 158) along the axial direction X1 of the linear
material or in TR direction (which is the direction towards the
rear end 163e). The spring member 166 is connected at one end
thereof to the mount 163c at the rear end 163e, and at the other
end connected to the slide table 161. The slide table 161 is thus
urged by the spring member 166 in TR direction. The stopper 163d is
screwed to the rear end 163e such that it is movable forward and
backward in the axial direction X1 of the linear material. As a
consequence, the leading end 163g projection from the rear end 163e
in TF direction may come into contact with the rear end 161a of the
slide table 161 (which is urged in TR direction by the spring
member 166) without touching the rear end 163e, thereby serving as
a stopper.
[0055] In the first embodiment, the outer circumference of the cam
member 165 increases in the counterclockwise direction d2, as shown
in FIG. 3. Thus, when the cam member 165 is rotated in the
clockwise direction d1 by a cam motor (not shown), the cam
receiving section 164 is pushed in TF direction along the slide
rails (163a and 163b) together with the integral slide table 161,
thereby causing the leading end of the point tool 160 on the slide
table 161 to approach the linear material feeder 158. On the other
hand, when the cam member 165 is rotated in the counterclockwise
direction d2, the periphery of the cam member 165 abutting against
the cam receiving member 164 is rotated by the urging force of the
spring member 166 acting in TR direction, so that the slide table
161 is moved in TR direction along the slide rails (163a and 163b)
and the point tool 160 comes off the linear material feeder
158.
[0056] It is noted that although there is only one point tool 160
in the first embodiment that can move back and forth in the axial
direction X1 of the linear material, a multiplicity of point tools
160 (coil diameter regulation means 162) (not shown) may be
radially arranged about the axis X2 of the coiling machine 150 such
that the multiplicity of point tools 160 are movable in the radial
direction about the axis X2 to regulate the coiling diameter of the
spring formed.
[0057] The pitch tool 154 is arranged adjacent the cored bar 153
and in the direction in which the bent linear material 1 extends,
such that the tip of the pitch tool 154 may abut against the bent
linear material 1. The pitch tool 154 is provided at the leading
end thereof with a pushing face 167, which is inclined in the
direction from the material entering position to the coil forming
direction (CF direction) so that it pushes the abutting linear
material 1 in the coil forming direction (CF direction). When
actuated by an actuator (not shown), the pitch tool 154 is not only
movable back and forth in CF direction and in the opposite CR
direction (FIG. 4) along line X3 that extends in the direction
perpendicular to the axis X1, but is also rotatable about line
X3.
[0058] As shown in FIGS. 4 and 5, the linear material 1, fed from
the linear material feeder 158 and bent by the abutting groove of
the point tool 160 in the direction perpendicular to coil forming
direction, is in contact with the pushing face 167 of the pitch
tool 154 while it is guided by the curved interior of cored bar
153. Since the linear material 1 in contact with the pushing face
167 is pushed in the coil forming direction (CF direction) by the
pushing face 167 as shown in FIG. 6, the linear material 1 is
spiraled to form a coil spring. The coiled linear material 1 is cut
by the cutting tool 55 that is movable to and away from the spring
forming stage 200 and pushed against the linear material 1.
[0059] The pitch of the coil spring thus formed increases in
proportion to the distance traveled by the pitch tool 154 in CF
direction while the tool is in contact with the pushing face
167.
[0060] In forming a conical spring, the coiling spring diameter is
gradually increased or decreased during coiling of the linear
material 1. In the coiling machine 150 of the first embodiment, a
conical spring is formed by moving the slide table 161 carried on
the point tool 160 to the right (TR direction) along the axis X1 as
shown in FIG. 6 for example, using a cam motor (not shown) to
gradually separate the point tool 160 away from the linear material
feeder 158 and bring the linear material 1 fed from the linear
material feeder 158 at a predetermined constant acceleration into
abutment with the abutting groove 159 of the point tool 160.
Alternatively, a conical spring may be formed by moving the slide
table 161 (point tool 160) at a predetermined constant acceleration
and bringing the linear material 1 fed from the linear material
feeder 158 at a regulated constant speed into contact with the
abutting groove 159.
[0061] Thus, the final configuration of the conical spring formed
may be easily and freely regulated between a bell-type, tapered
type, and bowl type configuration by regulating the feed
acceleration of linear material 1 in the case where the slide table
161 (point tool 160) is moved at a constant speed, or by regulating
the constant acceleration of the slide table 161 in the latter case
where the linear material is fed at a constant feed rate, as
described in more detail below.
[0062] Referring to FIG. 8, there is shown specific methods of
controlling the spring forming apparatus to form a conical spring.
FIG. 8(a) shows control methods in accordance with the respective
embodiments of the invention. In the upper left and right diagrams
of FIG. 8(a), abscissas represent time t of feeding a linear
material from the linear material feeder 158. The ordinate of the
upper left diagram represents the length X of the linear material
fed from the linear material feeder 158, while the ordinate of the
upper right diagram indicates the speed V of the linear material
feeder 158. The abscissa of the lower left diagram of FIG. 8(a)
represents time t of moving the slide table 161 carrying the point
tool 160, and the ordinate the displacement P (P also represents
the position for that displacement) of the slide table 161.
[0063] Through numerical control of a cam motor (not shown), the
point tool 160 causes the linear material 1 fed from the linear
material feeder 158 to be moved at a constant speed from P1 to P2
along the axis X1 over a period of time t2 as shown in the lower
left diagram of FIG. 8(a) while keeping the linear material in
abutment against the abutting groove 159. If the speed of the
linear material 1 fed from the linear material feeder 158 is
numerically controlled by a feed motor (not shown) and set to a
constant speed V0 throughout the feeding, a conventional bell type
conical spring having a concaved generatrix as shown in the upper
right diagram of FIG. 8(a) is formed.
[0064] In this embodiment, the spring forming apparatus is set up
such that the linear material is fed from the linear material
feeder 158 at a predetermined constant acceleration, that is, the
speed of the linear material 1 is set to V=a(t-t1)+V0 as shown in
the upper right diagram of FIG. 8(a), where "a" is a control
parameter associated with the acceleration that can be manually
varied by a worker in the integral range from 0 to 100 for example,
"t" denotes time of feeding the linear material 1, "t2" a total
time of feeding, "t1" a predetermined time smaller than t2, and
"V0" a constant associated with the predetermined speed. In trial
spring formations of conical springs, a worker presets the values
of t2, t1, and V0, and then varies the value of "a" in sequence,
for example 0, 1, 2, . . . and so on, to vary the feeding
acceleration until a desired load characteristic is obtained.
[0065] If the value of "a" is increased, the slope of V, or the
acceleration, of the fed linear material increases past the point
(t1, V0). Then length X of the linear material fed changes as shown
in the upper left diagram of FIG. 8(a). In other words, when a=0,
length X is given by X=VO t. In this case, the inclination of the
generatrix of the conical spring with respect to the axis L0 of the
spring becomes gradually steeper from the beginning to the end the
spring, thereby resulting in a bell shaped conical spring as shown
in the upper left diagram of FIG. 8(b).
[0066] On the other hand, as the worker increases the value of "a"
from a=0 to a=1, 2, 3, and so on, length X increases as
X=(a/2) t.sup.2+(V0-a t1) t,
as indicated by a solid curve in the upper left diagram of FIG.
8(a). Thus, the linear material is fed slowly in the first half
period and faster in the second half period as compared with the
case where "a" is set to zero, so that the inclination of the
generatrix with respect to the axis L0 becomes substantially
constant throughout the respective half periods. As a result, the
resultant conical spring formed has substantially a tapered
configuration as shown in the central diagram of FIG. 8(b).
[0067] If "a" is set to a value still larger than a preset value,
feeding is delayed or slowed in the first half period and faster in
the second half period that the generatrix of the resultant conical
spring is more steeper in the first half period but less steeper in
the second half period, as indicated by a dotted line in the upper
left diagram. As a result, the resultant conical spring will have a
bowl-like configuration as shown in the lower right diagram of FIG.
8(b).
[0068] In this way, the worker can delicately regulate the final
shape of the conical spring having different pitch rates, and hence
adjust the load characteristic of the conical spring, by simply
varying only one control variable "a" associated with feed
acceleration in the rage from a=0 to 100 for example as described
above. When a conical spring having a desired load characteristic
is included in the tested conical springs, the value of "a" for
that conical spring is the optimum value for the lot. Thus, mass
production of conical springs having a desired load characteristic
can be done using the optimum value. The worker only need to vary
one control parameter, feed acceleration say, and need not vary two
or more than two variables as in conventional cases. Thus, the
optimum value of "a" for a preferred load characteristic of conical
springs can be easily determined, and the load characteristic is
easily adjusted.
[0069] In the example above, the moving speed of the point tool 160
(slide table 161) is fixed to a constant speed while the
acceleration of feed rate of a linear material fed from the linear
material feeder 158 is varied. Alternatively, similar conical
springs including bell type, tapered type and bowl type springs may
be formed if, in setting up the coiling machine 150, the feed rate
of the linear material is fixed and the acceleration "a" of the
slide table 161 is varied in different ways such that its
displacement X and speed V satisfy X-t equation and V-t equation
shown in the upper left and right diagrams of FIG. 8. If a
multiplicity of point tools 160 (not shown) movable back and forth
are radially arranged about the axis X2 of a conical spring, each
of the slide tables 161 associated with the respective point tool
160 be moved with a regulated constant acceleration in accord with
the equations as indicated in the upper left and right diagrams of
FIG. 8.
[0070] On the other hand, the load characteristic of a conical
spring can be adjusted by varying its pitch. The load
characteristic of a conical spring is weakened if the pitch is
increased in the small diameter section and reduced in the larger
diameter section, and conversely strengthen if the pitch is
increased in the small diameter section and reduced in the large
diameter section.
[0071] From this point of view, adjustment of the load
characteristic of a conical spring may be achieved by regulating
the constant acceleration of the pitch tool 154 moving in the coil
forming direction (CF direction), instead of regulating the
acceleration of the slide table 161 (point tool 160) and the
feeding acceleration.
[0072] When the pitch tool 154 is moved by an actuator mechanism
(not shown) at a constant acceleration in CF direction during
forming a conical spring, the pitch of the conical spring increases
in CF direction of FIG. 6 at an accelerated rate. In this way, the
resultant configuration, and hence the load characteristic, of the
spring can be delicately adjusted, since the pitch of the spring is
changed.
[0073] Thus, the shape and load characteristic of a conical spring
can be preferably regulated by setting up the coiling machine 150
in such a way that the pitch tool 154 is moved at a constant
acceleration "a" (wherein the displacement X and speed V of the
pitch tool 154 obey the respective defining equations indicated in
the upper right and left diagrams of FIG. 8, with both of the feed
rate (or feeding acceleration) of the linear material 1 fed from
the linear material feeder 158 and the moving speed (or moving
acceleration) of the slide table 161 set to fixed values.
[0074] In setting up the coiling machine 150, the worker can
delicately control the load characteristic of conical springs
including bell shape, tapered shape, and bowl shape springs by
varying only one control parameter, the acceleration "a", of the
slide table 161 over the range from 0 to 100, for example (or the
acceleration of the pitch tool in the case where the load
characteristic is adjusted using the pitch tool 154). If a conical
spring having a desired load characteristic is found among the
conical springs tested for a particular value of "a" for a given
lot, desirable conical springs can be mass-produced from the lot
with that set value. It should be appreciated that the worker can
again easily adjust the load characteristic by simply varying one
control parameter associated with the acceleration of the coiling
machine.
[0075] Next, referring to FIGS. 9 through 12, a second load
characteristic adjustment system of the invention will now be
described.
[0076] As opposed to the first embodiment where the point tool 160
is moved with the linear material feeder 158 fixed, the quill 10
(which corresponds to the linear material feeder 158 of the first
embodiment) is moved in the axial direction X1 of the linear
material with a coil forming tool 120 (which corresponds to the
point tool 160) fixed in the second embodiment.
[0077] As shown in those figures, a spring forming apparatus 300
utilizing such second load characteristic adjustment system
includes: a linear material feeding means 20 having a pair of
pressure rollers 22 for feeding a linear material 1 to a spring
forming stage 100 (FIG. 9) via the quill 10 serving as a linear
material guide; and a coil forming tool 120 movable towards, and
away from, the spring forming stage 100; wherein the coil forming
tool 120 is moved forward to the spring forming stage 100 to abut
against the linear material 1 fed from the spring forming stage 100
provided at the leading end of the quill 10, thereby spiraling the
linear material 1.
[0078] Reference numeral 3 indicates a fixed frame provided on a
cradle 2. Mounted on the fixed frame 3 is a linear-way slide 50
(serving as a coil diameter regulating means of the claims) for
dynamically varying the distance between the coil forming tool 120
and quill 10 by moving the quill 10 along the axis X1 of the linear
material 1. Also mounted on the fixed frame 3 is a slide table 52,
which is slidable on the frame 3 in the direction of the axis X1 of
the linear material 1. The slide table 52 integrally bears thereon
the quill 10 and the linear material feeding means 20 via a slide
frame 4. The quill 10 integral with the slide table 52 can be moved
in the forward direction (KF direction) and backward direction(KR
direction) along the axis X1 of the linear material 1 as shown in
FIG. 10, via a ball screw 54 which is rotated by a servo-motor M50
mounted on the fixed frame 3. The pressure rollers 22 are subjected
to a driving force of the M22 via a gear mechanism (not shown). The
upper one of the rollers 22 is rotated in the counterclockwise
direction, while the lower one is rotated in the clockwise
direction, thereby feeding the linear material 1 held therebetween
from the quill 10 to the spring forming stage 100.
[0079] Arranged above, and in the direction perpendicular to, the
axis X1 of the linear material 1 is a linear slide 110. This linear
slide 110 has a tool slide table 112 bearing thereon the coil
spring forming tool 120. The tool slide table 112 is moved by a
servo-motor M110 forward and backward relative to the spring
forming stage 100 provided at the leading end of the quill 10. A
crank mechanism 114 for converting the rotational motion of the
servo-motor M110 to a linear motion is arranged between the output
shaft of the servo-motor M110 and the tool slide table 112, which
mechanism controls the forward and backward motion of the tool
slide table 112.
[0080] The coil forming tool 120 has a tool rotation unit 131 and a
servo-motor M132. The tool rotation unit 131 and the servo-motor
132 are mounted on a movable tool slide table 112. The tool unit
131 is provided on a rotatable tool holder thereof with a pair of
right-handed and left-handed coil forming tools 134A and 134B,
respectively, which are facing each other across the rotary shaft
133. The tool holder 132 is a rotary body having a rotational axis
parallel to the direction of forward/backward movement of the tool
slide table 112. Reference numerals 132a and 133b indicate a gear
mounted on the output shaft of the servo-motor M132 and a gear
mounted on the rotational shaft 133, respectively. The driving
force of the motor is transmitted to the tool rotational unit 131
by these gears.
[0081] In this coil forming tool 120C, the right- and left-handed
coiling tools 134A and 134B, respectively, can be easily exchanged
in position by operating the servo-motor M132, so that the tools
134A and 134B can be easily switched between them for abutment on
the linear material 1.
[0082] As shown in FIG. 11(a)-(c), the tool holder 132 has a
generally flattened square block configuration, and is provided at
the right and left corners thereof with a right- and a left-handed
coiling tool 134A and 134B, respectively, such that these tools
have respective abutting faces 136 and 137 facing each other in
their linear material engagement grooves 136a and 137a. The
engagement groove 136a for right-handed coiling of the linear
material consists of a pair of parallel grooves downwardly inclined
towards the right leading end of the right-handed coiling tool 134A
as shown in FIG. 11(b). On the other hand, the engagement groove
137a for left-handed coiling of the linear material consists of a
pair of parallel grooves downwardly inclined towards the left
leading end of the left-handed coiling tool 134B as shown in FIG.
11(c).
[0083] In forming a coil spring, the coil forming tool 120 is moved
towards the spring forming stage 100 in CF direction as indicated
in FIG. 10 under the control of the tool slide table 112 so that
the coiling tool 134A (or 134B) is arranged to face the quill 10
and is abutted on the linear material 1 fed from the leading end of
the quill 10. When the coiling tool 134A is facing the quill 10,
the linear material 1 is coiled in the right-handed coiling
direction along the right declining abutment groove 136a of FIG.
11(b), as shown in FIG. 12. On the other hand, if the tool holder
132 is rotated through 180.degree. by the servo-motor M132 so as to
bring the left-handed coiling tool 134B to face the quill 10, the
linear material 1 is coiled in the left-handed coiling direction by
the left declining abutment groove 137a.
[0084] The coiling diameter of the coil spring thus formed
increases in proportion to the distance from the coiling tool 134A
(or 134B) to the quill 10. For instance, to form a conical spring
as shown in FIG. 12, the slide table 52 carrying thereon the quill
10 feeding the linear material at a constant feeding acceleration
is moved at a constant speed by the numerically controlled
servo-motor M50 in the direction KR along the axis X1 shown in FIG.
10, so that the quill 10 is moved away from the coiling tool 134A
(or 134B) while keeping the linear material 1 in abutment against
the abutment groove 136a (or 137a). Alternatively, the quill 10
mounted on the slide table 52 and feeding the linear material 1 at
a constant feed rate is moved by the servo-motor M50 at a constant
acceleration in KR direction along the axis X1 as shown in FIG. 10
while keeping the linear material 1 in abutment against the
abutment groove 136a (or 137a).
[0085] For example, in setting up the spring forming apparatus 300,
the slide table 52 (quill 10) may be set to a constant speed while
the feed acceleration of the linear material is set to a constant
magnitude by regulating the value of "a" such that the feed length
X and feed rate V of the linear material satisfies the defining
equation indicated in the upper right and left diagrams of FIG. 8.
Alternatively, the feed rate of the linear material 1 fed from the
quill 10 may be set to a constant speed and the value of "a" may be
set so that the acceleration of the slide table 52 (quill 10) to
remain constant and that displacement X and moving speed V of the
slide table 52 (quill 10) satisfy the defining equation indicated
in upper right and left diagrams of FIG. 8, as opposed to the
preceding example.
[0086] In this case, the worker setting up the spring forming
apparatus 300 to adjust the load characteristic of a conical spring
by controlling the movement of the slide table 52 can delicately
and easily regulate the resultant configuration (among bell type,
tapered type, and bowl type configuration), or the pitch, of the
conical spring to be formed by simply controlling only one
parameter such as "a" associated with the acceleration of the slide
table 52 in the range from 0 to 100.
SYMBOLS
[0087] 1 linear material [0088] 151 linear material feed unit
(linear material feeding means) [0089] 154 pitch tool (spiraling
means) [0090] 158 linear material feeding means [0091] 160 point
tool (spring forming tool) [0092] 162 coil diameter regulating
means [0093] X1 axis of the linear material [0094] "a" acceleration
parameter [0095] 10 quill (linear material feeder) [0096] 20 linear
material feeding means [0097] 50 linear-way slide (coil diameter
regulating means) [0098] 120 coil forming tool (spiraling means)
[0099] 136a right declining linear material abutting groove
(spiraling means) [0100] 137a left declining linear material
abutting groove (spiraling means)
* * * * *