U.S. patent application number 11/841275 was filed with the patent office on 2008-02-21 for linear motor mounted press machine and press working method.
This patent application is currently assigned to MURATA KIKAI KABUSHIKI KAISHA. Invention is credited to Hiroichi SAKAMOTO.
Application Number | 20080041243 11/841275 |
Document ID | / |
Family ID | 38650097 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080041243 |
Kind Code |
A1 |
SAKAMOTO; Hiroichi |
February 21, 2008 |
LINEAR MOTOR MOUNTED PRESS MACHINE AND PRESS WORKING METHOD
Abstract
The present invention provides a linear motor mounted press
machine that allows both a punch and a die to be driven to enable
various types of machining, the linear motor mounted press machine
having a simple configuration and enabling accurate machining. The
present invention is applied to a press machine that performs a
press working on a workpiece W by means of a punch 61 and a die 62.
A punch linear motor 1 is installed in an upper frame 41b of a
press frame 41 to drivingly elevate and lower the punch 61. A die
linear motor 1A is installed in a lower frame 41c of the press
frame 41 to drivingly elevate and lower the die 62.
Inventors: |
SAKAMOTO; Hiroichi;
(Inuyama-shi, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW, SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
MURATA KIKAI KABUSHIKI
KAISHA
Kyoto-shi
JP
|
Family ID: |
38650097 |
Appl. No.: |
11/841275 |
Filed: |
August 20, 2007 |
Current U.S.
Class: |
100/39 ; 100/102;
72/338; 83/13; 83/613 |
Current CPC
Class: |
Y10T 83/04 20150401;
B30B 15/148 20130101; Y10T 83/8821 20150401; B30B 1/42
20130101 |
Class at
Publication: |
100/39 ; 100/102;
72/338; 83/13; 83/613 |
International
Class: |
B21D 28/04 20060101
B21D028/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2006 |
JP |
2006-223779 |
Claims
1. A linear motor mounted press machine that presses a workpiece
using a punch and a die both located in a press drive axis center,
the press machine being characterized by comprising a press frame
having an upper frame and a lower frame, a punch linear motor
provided in the upper frame to drivingly elevate and lower the
punch, and a die linear motor provided in the lower frame to
drivingly elevate and lower the die.
2. A linear motor mounted press machine according to claim 1,
characterized in that one or both of the punch linear motor and the
die linear motor are unit linear motor assemblies each including a
plurality of unit linear motors around the press drive axis center,
each of the unit linear motors having an output shaft that is
parallel to the press drive axis center.
3. A linear motor mounted press machine according to claim 1,
characterized in that the die linear motor has a hole in an area
thereof which coincides with the press drive axis center, slag
resulting from the press working being discharged from the
hole.
4. A linear motor mounted press machine according to claim 1,
characterized in that the die linear motor is a unit linear motor
assembly including a plurality of unit linear motors around the
press drive axis center, each of the unit linear motors having an
output shaft that is parallel to the press drive axis center, the
die linear motor having a hole in an area thereof which coincides
with the press drive axis center, slag resulting from the press
working being discharged from the hole.
5. A linear motor mounted press machine according to claim 1,
characterized by comprising control means for drivingly elevating
and lowering both the punch and the die relative to the workpiece
for the press working.
6. A press working method for performing a press working on a
workpiece by using a linear motor mounted press machine, the method
being characterized in that: the press machine comprises a press
frame having an upper frame and a lower frame, a punch linear motor
provided in the upper frame to drivingly elevate and lower the
punch, and a die linear motor provided in the lower frame to
drivingly elevate and lower the die, and the method performs
punching by carrying out both lowering of the punch by means of the
punch linear motor and elevation of the die by means of the die
linear motor.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a press machine such as a
punch press which uses linear motors as a driving source, and a
press working method for performing a press working by using the
press machine.
BACKGROUND OF THE INVENTION
[0002] Press machines such as punch presses commonly use, as a
press driving source that moves punches forward and backward, a
mechanism that converts rotary motion of rotary type electric
motors into rectilinear motion via a crank mechanism and so on, or
hydraulic cylinders. A proposal has also been made of press
machines using servo motors as electric motors to vary punch speed
during strokes.
[0003] However, press machines using rotary type electric motors
require a mechanism that converts rotary motion into rectilinear
motion and thus have complicated configurations. Further, since
rotary motion is converted into rectilinear motion, lost motion or
the like may occur, degrading controllability. Press machines using
a hydraulic cylinder require a hydraulic supply system such as a
hydraulic unit and thus have complicated structures.
[0004] Attempts have also been made to use linear motors as a press
driving source. When used to drive punches, linear motors, unlike
rotary type motors, eliminate the use of a mechanism that converts
a rotation into a rectilinear motion. The linear motor thus reduces
the number of parts required and simplifies the structure.
[0005] Some conventional punch presses are used for a forming
process. It is well known that punch presses can be commonly used
for hole making and shape forming. Some punch presses include a die
constituting a lower tool and configured as a recessed tool, and a
punch configured as a projecting tool, to perform shape forming on
a plate-like workpiece such that the work piece has a portion
projecting from its bottom surface. The portion resulting from the
shape forming projects from the bottom surface of the workpiece and
may thus interfere with feeding of the workpiece on a table.
[0006] On the other hand, some commercialized punch presses include
a die constituting a lower tool, and configured as a projecting
tool, and a punch configured as a recessed tool as opposed to the
above press machines, to perform shape forming on the workpiece
such that the workpiece has a portion projecting from its top
surface. When the die is thus configured as a projecting tool and
always projects above a die height, the bottom surface of the
workpiece may be damaged by the die when the workpiece is fed. A
proposal has thus been made of punch presses which normally allow
such a projecting shape forming die to stand by below the die
height and which project the die above the die height during
operation (for example, the Unexamined Japanese Patent Application
Publication (Tokkai-Hei) No. 11-156459). The die is elevated and
lowered by a cylinder device that moves forward and backward in a
horizontal direction and a cam, a link mechanism, or the like which
converts the horizontal operation of the cylinder device into a
vertical operation.
[0007] In the conventional press machines using linear motors, the
punch is driven, and the die is fixed. When such a press machine
has a shape-forming or hole-making die installed so as to be able
to elevate and lower in order to provide multiple functions, where
a cylinder device is used as a mechanism for elevating and lowering
the die, elevating and lowering strokes are fixed. This precludes
the forming process such that the resulting workpieces have
different projection heights. Press machines using servo motors and
ball screws as a die elevating and lowering mechanism can achieve
the forming process such that the resulting workpieces have
different projection heights. However, these press machines have
complicated configurations like those which drive the punch.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a linear
motor mounted press machine that allows both a punch and a die to
be driven to enable various types of machining, the linear motor
mounted press having a simple configuration and enabling accurate
machining. It is another object of the present invention to provide
high power while avoiding difficulties with manufacture. It is yet
another object of the present invention to facilitate discharge of
slag resulting from hole making or the like while enabling the die
to be driven by a linear motor located immediately below the die.
It is still another object of the present invention to drive both
the die and the punch to machine a workpiece, enabling various
types of machining.
[0009] A linear motor mounted press machine in accordance with the
present invention presses a workpiece using a punch and a die both
located in a press drive axis center. The press machine comprises a
press frame having an upper frame and a lower frame, a punch linear
motor provided in the upper frame to drivingly elevate and lower
the punch, and a die linear motor provided in the lower frame to
drivingly elevate and lower the die.
[0010] This configuration uses the linear motor to drivingly
elevate and lower the punch. Thus, unlike configurations using
rotary type motors, this configuration eliminates the need for a
mechanism that converts the rotation into the rectilinear motion.
This reduces the number of parts required and simplifies the
structure of the press machine. Further, the die is also drivingly
elevated and lowered by the linear motor. Thus, compared to
configurations that drivingly elevate and lower the die via a
horizontal cylinder device and a cam, a link mechanism, or the
like, this configuration is simple and offers excellent
controllability to allow die elevating and lowering strokes to be
accurately controlled. This configuration thus allows both the
punch and the die to be driven to enable various types of machining
and drives both the punch and the die using the linear motor. This
simplifies the configuration and enables accurate machining.
[0011] In the present invention, one or both of the punch linear
motor and the die linear motor may be unit linear motor assemblies
each including a plurality of unit linear motors around the press
drive axis center, each of the unit linear motors having an output
shaft that is parallel to the press drive axis center. Punch
working may require a high thrust. Linear motors generally use
permanent magnets with a strong magnetic force. However, it is
difficult to manufacture motors each providing a high thrust owing
to the manufacturing limit on the size of magnets, limitations on
supply voltage, or the like. However, the assembly of the plurality
of unit linear motors described above allows the power of the
individual unit linear motors to be collectively utilized,
providing the high power.
[0012] In the present invention, the die linear motor may have a
hole in an area thereof which coincides with the press drive axis
center, slag resulting from the press working being discharged from
the hole. The press drive axis center corresponds to the center of
a ram shaft, that is, the center of the punch and die. The die-side
liner motor is located below the die. Thus, the die-side linear
motor does not pose any problem during shape forming but may
interfere with discharge of slag during hole making. Accordingly,
the hole for slag discharge is formed in the area of the die linear
motor which coincides with the press drive axis center. This
enables slag to be smoothly discharged while the die is being
driven using the linear motor.
[0013] In particular, where the die linear motor is a unit linear
motor assembly including a plurality of unit linear motors around
the press drive axis center, each of the unit linear motors having
an output shaft that is parallel to the press drive axis center,
the die linear motor preferably has a hole in an area thereof which
coincides with the press drive axis center, slag resulting from the
press working being discharged from the hole. Where the die linear
motor is the assembly of the unit linear motors, the press machine
can be easily configured so that the hole for slag discharge is
formed in the press drive axis center.
[0014] The linear motor mounted press machine in accordance with
the present invention may comprise a control means for drivingly
elevating and lowering both the punch and the die relative to the
workpiece for performing the press working. Various types of
machining can be performed on the workpiece by simultaneously
driving both the punch and the die or sequentially driving the
punch and the die to machine one point. When both the punch and the
die are thus drivingly elevated and lowered for the press working,
the excellent controllability of the linear motors can be
effectively utilized. Therefore, the present invention, using the
linear motor as a driving source for both the punch and the die,
can effectively increase accuracy.
[0015] A press working method in accordance with the present
invention uses the linear motor mounted press machine having one of
the above configurations, and to drivingly elevate and lower both
the punch and the die relative to the workpiece for performing the
press working. According to this method, the linear motor mounted
press machine in accordance with the present invention, using the
linear motor as a driving source for both the punch and the die,
can effectively increase accuracy, and this allows various types of
punch working to be accurately performed. The term "punch working"
as used herein refers to hole making or shape forming.
[0016] The linear motor mounted press machine in accordance with
the present invention performs the press working on the workpiece
by means of the punch and the die both located in the press drive
axis center. The linear motor mounted press machine comprises the
press frame having the upper frame and the lower frame, the punch
linear motor provided in the upper frame to drivingly elevate and
lower the punch, and the die linear motor provided in the lower
frame to drivingly elevate and lower the die. This configuration
thus allows both the punch and the die to be driven to enable
various types of machining. In spite of this function, the
configuration is simple and enables accurate machining.
[0017] When one or both of the punch linear motor and the die
linear motor are the unit linear motor assemblies each including
the plurality of unit linear motors around the press drive axis
center, each of the unit linear motors having the output shaft that
is parallel to the press drive axis center, the difficulties with
the manufacture of the linear motors can be avoided, and high power
is provided.
[0018] Where the die linear motor has a hole in an area thereof
which coincides with the press drive axis center, slag resulting
from the press working being discharged from the hole, then slag
resulting from hole making or the like can be easily discharged,
while enabling the die to be driven.
[0019] Where the die linear motor is a unit linear motor assembly
including a plurality of unit linear motors around the press drive
axis center, each of the unit linear motors having the output shaft
that is parallel to the press drive axis center, and the die linear
motor has a hole in an area thereof which coincides with the press
drive axis center, slag resulting from the press working being
discharged from the hole, then the difficulties with the
manufacture of the linear motors can be avoided, and the high power
is provided. Further, slag resulting from hole making or the like
can be easily discharged.
[0020] Where the linear motor mounted press machine includes a
control means for drivingly elevating and lowering both the punch
and the die relative to the workpiece for performing the press
working, various types of machining can be performed on the
workpiece by driving both the die and the punch to machine the
workpiece. Furthermore, the machining can be accurately
performed.
[0021] The press working method in accordance with the present
invention performs the press working by using the linear motor
mounted press machine of the present invention, to drivingly
elevate and lower both the punch and the die relative to the
workpiece. Various types of machining can thus be performed on the
workpiece by driving both the die and the punch to machine the
workpiece. Furthermore, the machining can be accurately
performed.
[0022] Other features, elements, processes, steps, characteristics
and advantages of the present invention will become more apparent
from the following detailed description of preferred embodiments of
the present invention with reference to the attached drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is an exploded side view of a linear motor mounted
press machine in accordance with an embodiment of the present
invention.
[0024] FIG. 2 is a vertical sectional view of a punch linear motor
in the press machine.
[0025] FIG. 3 is a sectional view of the punch linear motor along
line III-III in FIG. 2.
[0026] FIG. 4 is a vertical sectional view of a die linear motor in
the press machine.
[0027] FIG. 5 is a diagram illustrating the operation of the press
machine.
[0028] FIG. 6 is a vertical sectional view of a variation of the
die linear motor in the press machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] An embodiment of the present invention will be described
with reference to FIGS. 1 to 5.
[0030] The press machine is a punch press that uses a punch 61 and
a die 62 to perform a press working on a plate-like workpiece W
such as a sheet metal. The press machine comprises a press frame
41, a punch linear motor 1 provided in an upper frame 41b of the
press frame 41 to elevate and lower the punch 61, and a die linear
motor 1A provided in a lower frame 41c to elevate and lower the die
62.
[0031] The press frame 41 comprises the upper frame 41b, the lower
frame 41c and a column portion 41a to which the upper frame 41b and
the lower frame 41c are coupled, and the press frame 41 is open in
a front surface and has a C-shaped side surface. A vertical pair of
tool supports 42, 43 and a workpiece feeding mechanism 44 are
installed between the upper frame 41b and the lower frame 41c. A
press mechanism 45 using the punch linear motor 1 as a driving
source is installed in the upper frame 41b. The press frame 41 may
be a gate-, ring-, or hollow-rectangle-like frame in which the
upper and lower frame portions with an equivalent length are
coupled together at a front end and a rear end by the column
portion.
[0032] The tool supports 42, 43 comprise an upper turret and a
lower turret which are concentrically installed and each of which
has punches 61 and dies 62 mounted at a plurality of points in a
circumferential direction thereof. Rotation of the tool supports
42, 43 allows each of the punches 61 and the dies 62 to be indexed
to a predetermined punch position P.
[0033] In FIG. 1, the workpiece feeding mechanism 44 uses a
workpiece holder 47 to grip an edge of the plate like workpiece W
to move it on a table 48 forward, backward, rightward, and
leftward.
[0034] The press mechanism 45 supports a ram 49 that elevates and
lowers the punch 61 indexed to the punch portion P in the tool
support 42 so that the ram 49 can be freely elevated and lowered by
a ram guide 50. The ram 49 is drivingly elevated and lowered by an
output shaft 12 of the linear motor 1.
[0035] As shown in FIG. 2 and FIG. 3, the punch linear motor 1 has
a plurality of unit linear motors 2 composed of cylindrical linear
motors and juxtaposed in a motor case 25. In this example, the
juxtaposition form is such that the cylindrical linear motors 2
made in accordance with the same specifications are arranged on a
virtual circle around the center 0 of the output shaft, that is, a
press drive axis center, in its circumferential direction.
[0036] Each of the unit linear motors 2 comprises a shaft member 3
composed of a permanent magnet having alternately arranged N pole
and S pole, and a coil unit 4 through which the shaft member 3 is
movable in an axial direction relative to the coil unit 4. The coil
unit 4 is composed of a plurality of coils 5 arranged in a
cylindrical coil case 7 in the axial direction and surrounding the
shaft member 3. The coil unit 4 constitutes a stator, and the shaft
member 3 constitutes the output shaft of the motor 2, which
constitutes a moving member of the unit linear motor 2. The shaft
member 3 is composed of one round bar-like member but may be
composed of a plurality of permanent magnets arranged in the axial
direction.
[0037] The motor case 25 has an inner cylinder 26 and an outer
cylinder 27 arranged concentrically with each other, and end plates
28, 29 that couple the opposite ends of the inner cylinder 26 and
the outer cylinder 27 together. The unit linear motors 2 are
arranged in the annular space between the inner cylinder 26 and the
outer cylinder 27 in the circumferential direction. The opposite
ends plates 28, 29 have a plurality of shaft member insertion holes
28a, 29a through which the shaft member 3 of each unit linear motor
2 is inserted, and the end plate 28 has a guide shaft insertion
hole 28b in its center.
[0038] The shaft members 3 of the unit linear motors 2 are coupled
together at their opposite ends by coupling members 10, 11, and the
plurality of shaft members 3 and the coupling members 10, 11
constitute a moving member 30. The coupling member 11 of the moving
member 30 has the output shaft 12 located in the center 0 of the
arrangement of the unit linear motors 2.
[0039] A guide mechanism 32 is provided between the motor case 25
and the moving member 30 to guide movement of the shaft members 3
of the plurality of unit linear motors 2. The guide mechanism 32 is
composed of an inner cylinder 26 of the motor case 25, a bush 15
that is a guide portion fixedly fitted into the inner cylinder 26,
and a guide shaft 13, as a guided portion, provided at the center
of one end side of the coupling member 10 and fitted into a bush 15
so as to be movable in the axial direction. The bush 15 constitutes
a sliding shaft. Instead of the bush 15, a direct-acting roll
bearing may be interposed.
[0040] The guide mechanism 32 has a rotation inhibiting means 16
for inhibiting rotation of the moving member 30 relative to the
motor case 25. The rotation inhibiting means 16 comprises a key
groove 17 formed in the guide shaft 13 along the axial direction
and a key portion 18 fixed to the inner cylinder 26 of the motor
case 25 and slidably engaged with the key 17.
[0041] FIG. 4 shows the die linear motor 1A. The die linear motor
1A has a slag discharge hole 70 formed in its center. Each unit
linear motor 2 has a bush 15A in place of the guide mechanism 32 of
the punch linear motor 1 in FIG. 2 and FIG. 3. The slag discharge
hole 70 comprises the internal space in the inner cylinder 26 of
the motor case 25. The center of the slag discharge hole 70
coincides with the press drive axis center that is the center of
the punch position P.
[0042] The coupling member 11 on an output side of the die linear
motor 1A has an output shaft 12A comprising a hollow shaft and
internally constituting a slag discharge hole, the output shaft 12A
projecting upward. The remaining part of the configuration of the
die linear motor 1A is similar to that of the punch linear motor 1,
described with reference to FIG. 2 and FIG. 3, and duplicate
descriptions are thus omitted.
[0043] The punches 61 installed on the upper tool support 42 and
the dies 62 installed on the lower tool support 43 in FIG. 1
include a punch 61.sub.1 and a die 62.sub.1 for hole making shown
in FIG. 5A and a punch 61.sub.2 and a die 62.sub.2 for shape
forming shown in FIG. 5B and FIG. 5C. The hole-making punch
61.sub.1 is fixedly installed on the lower tool support 43 via a
die holder 63.
[0044] The shape-forming punch 61.sub.2 is recessed and has a
recessed portion 65 on its bottom surface. The shape forming die
62.sub.2 is projecting and has a projecting portion 66 at the top.
The shape forming die 62.sub.2 is installed so as to be able to
elevate from and lower to the die holder 63, installed on the lower
tool support 43. In a lowered condition, the shape forming die
62.sub.2 is located below a die height DH. The shape forming die
62.sub.2 is pushed up above the die height DH by the output shaft
12A of the die linear motor 1A.
[0045] The shape forming die 62.sub.2 has an output shaft engaging
projection 67 provided on its bottom surface. During elevation, an
upper end of the output shaft 12A of the die linear motor 1A is
pressed against the bottom surface of the output shaft engaging
projection 67. The shape forming die 62.sub.2 is urged downward by
a return spring (not shown in the drawings).
[0046] A hollow hole 69A is formed at the installation position of
each die 62 of the lower tool support 43, comprising a turret; the
output shaft 12A of the die linear motor 1A is advanced through the
hollow hole 69A so as to be able to elevate and lower. A bolster 68
that receives the tool support 43 comprises a pair of bolster
components, and the area between the bolster components constitutes
a hollow space 69B through which the output shaft 12A of the die
linear motor 1A is advanced so as to be able to elevate and
lower.
[0047] In FIG. 1, a control device 81 controlling the press machine
comprises a computerized numerical control device, and the control
device 81 has an arithmetic control section 83 that analyzes and
executes a processing program 82. The control device 81 thus gives
instructions to the linear motors 1, 1A, servo motors for shafts of
the workpiece feeding mechanism 44, and a driving source (not shown
in the drawings) for indexation rotation of the tool supports 42,
43. The control device 81 has a control means 84 for drivingly
elevating and lowering the punches 61 and the dies 62 by means of
the linear motors 1, 1A for performing the press working. The
control means 84 is composed of instructions described in the
processing program 82 as well as the arithmetic control section
83.
[0048] A description will be given of the operation of the press
machine configured as described above.
[0049] As shown in FIG. 5A, the die linear motor 1A is normally in
the lowered condition, and the upper end of the output shaft 12A is
located below the bottom surface of the lower tool support 43. This
enables the tool support 43, comprising a turret, to be rotated
without interfering with the output shaft 12A. Further, as shown in
FIG. 5B, the upper end of the form-shaping die 62.sub.2 is located
below the die height DH. In this condition, the upper tool support
42 and the lower tool support 43 are rotated to index any of the
punches 61 and the dies 62 to the punch position P. This prevents
the shape-forming die 62.sub.2 from coming into sliding contact
with the bottom surface of the workpiece W to damage it.
[0050] Punch working such as normal hole making is performed by
drivingly lowering the punch 61 of the upper tool support 42 by
means of the punch linear motor 1 with the die linear motor 1A thus
lowered. Slag resulting from hole making falls down from the
machine through the slag discharge hole 70, formed in the center of
the die linear motor 1A.
[0051] For shape forming, the upper tool support 42 and the lower
tool support 43 are rotated to index the shape forming die 62.sub.2
to the punch center P as shown in FIG. 5B. This positions the shape
forming die 62.sub.2 immediately above the output shaft 12A of the
die linear motor 1A. In this condition, as shown in FIG. 5C, the
die linear motor 1A is allowed to perform elevational driving so
that its output shaft 12A elevates the shape-forming die 62.sub.2
to a predetermined height. Further, the shape-forming punch
61.sub.2 is lowered by the punch linear motor 1 so as to sandwich
the workpiece W between the shape-forming punch 61.sub.2 and the
shape-forming die 62.sub.2. This allows a shape forming portion Wa
to be formed in the workpiece W by pressing.
[0052] Once shape forming is finished, the punch linear motor 1 is
elevated, and the die linear motor 1A is lowered. Thus, the shape
forming portion Wa formed by the punch working projects upward from
the workpiece W and thus does not interfere with feeding of the
workpiece W on the table 48 by means of the workpiece feeding
mechanism 44.
[0053] The press machine configured as described above uses the
linear motor 1 as a press driving source. Compared to press
machines using rotary motors, this press machine thus does not need
any mechanism that converts the rotation into the rectilinear
motion of the ram 49, and this also reduces the number of parts
required for the press mechanism 45 and simplifies its
configuration. Further, compared to press machines using a
hydraulic cylinder as a press driving source, this press machine
eliminates the need for the hydraulic unit, simplifying the
configuration. Furthermore, the linear motor 1 offers excellent
positional accuracy, enabling high-quality, accurate machining.
[0054] The shape forming die 62.sub.2 is also drivingly elevated
and lowered by the linear motor 1A. Thus, compared to conventional
press machines using a horizontal cylinder device and a cam, a link
mechanism, or the like for elevating and lowering driving, this
press machine has a simple configuration, offers excellent
controllability, and enables the accurate control of the elevating
and lowering strokes of the shape-forming die 62.sub.2. Thus, both
the punch 61 and the die 62 can be driven to enable various types
of machining, and the linear motors 1, 1A are used to drive the
punch 61 and the die 62, respectively. This simplifies the
configuration and enables accurate machining.
[0055] Each of the punch linear motor 1 and the die linear motor 1A
is the unit linear motor assembly including the plurality of unit
linear motors 2 around the press drive axis center; each of the
unit linear motors 2 has the output shaft that is parallel to the
press drive axis center. This provides high power. Punch working
may require a high thrust. However, the linear motors generally use
permanent magnets with a strong magnetic force. Accordingly, it is
difficult to manufacture motors each providing a high thrust owing
to the manufacturing limit on the size of magnets, limitations on
supply voltage, or the like. However, in the present embodiment,
each of the linear motors 1, 1A includes the assembly of the
plurality of unit linear motors 2, allowing the power of the
individual unit linear motors 2 to be collectively utilized,
providing high power.
[0056] Further, the die linear motor 1A has the slag discharge hole
70 in the area thereof which coincides with the press drive axis
center so that slag resulting from the press working can be
discharged from the slag discharge hole 70. Slag can thus be
smoothly discharged. This prevents the die linear motor 1A from
interfering with discharge of slag even though the die linear motor
1A is installed below the hole-making die 61.sub.1. Since the die
linear motor 1A is the assembly of the plurality of unit linear
motors 2, the press machine can be easily configured so that the
slag discharge hole 70 is formed in the press drive axis
center.
[0057] Further, the present linear motor mounted press machine
operates under the control of the control means 84 in FIG. 1, and
as described in conjunction with FIG. 5C, both the punch 61 and the
die 62 are drivingly elevated and lowered for the press working.
Thus, various types of machining can be performed on the workpiece
W by simultaneously driving both the punch 61 and the die 62 or
sequentially driving the punch 61 and the die 62 to machine one
point, the shape forming portion Wa. When both the punch 61 and the
die 62 are thus drivingly elevated and lowered for the press
working, the excellent controllability of the linear motors 1, 1A
can be effectively utilized. Therefore, accuracy can be effectively
increased by using the linear motors 1, 1A as a driving source for
both the punch 61 and the die 62.
[0058] In the above embodiment, each of the punch linear motor 1
and the die linear motor 1A comprises the assembly of the plurality
of unit linear motors 2. However, a unitary linear motor that is a
single larger unit linear motor 2 may be used. In this case, the
die linear motor 1A preferably has the slag discharge hole 70
penetrating the center of the shaft member 3, for example, as shown
in FIG. 6.
[0059] While the present invention has been described with respect
to preferred embodiments thereof, it will be apparent to those
skilled in the art that the disclosed invention may be modified in
numerous ways and may assume many embodiments other than those
specifically set out and described above. Accordingly, it is
intended by the appended claims to cover all modifications of the
present invention that fall within the true spirit and scope of the
invention.
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