JP2006212640A - Sheet material forming machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet material forming machine which can set a platy workpiece with respect to a definite datum, and can form the workpiece by moving it at a high speed, and can improve the forming accuracy of the workpiece, and can smoothly perform a forming operation by eliminating the interference of a carriage with a forming head, and has a simple configuration. <P>SOLUTION: The sheet material forming machine comprises a base member which can move in the y-axis direction, a first slider which can move in the x-axis direction, a second slider which is arranged on the base member and can move in the x-axis direction, a first gripping means for integrally setting the worpiece on the first slider, a second gripping means for integrally setting the worpiece on the second slider, and the forming head for forming the workpiece. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plate material processing machine, and more particularly, to a machine that processes the plate material by holding both sides of the plate material and moving the plate material.

  2. Description of the Related Art Conventionally, there is known a plate material processing machine configured to move a plate-shaped workpiece in the x-axis direction and move the punch and die in the y-axis (axis perpendicular to the x-axis) to process the workpiece. (For example, see the description corresponding to FIG. 5 and FIG. 5 of Patent Document 1).

  More specifically, the plate material processing machine described in Patent Document 1 is provided with a first rail installed extending in the x-axis direction, and extending in the x-axis direction away from the first rail in the y-axis direction. And an x-axis carriage having one end engaged with the first rail and the other end engaged with the second rail and movable in the x-axis direction. An x-axis motor that drives the x-axis carriage via a ball screw, and a y-axis carriage that is movable in the y-axis direction with respect to the x-axis carriage on the one end side of the x-axis carriage A y-axis motor that drives the y-axis carriage via a ball screw, a first clamp mechanism provided on the y-axis carriage for gripping the workpiece, and the y-axis for gripping the workpiece Provided on the shaft carriage A second clamping mechanism, and a punch die.

  Then, by positioning the y-axis carriage at an appropriate position, a workpiece having an arbitrary width is gripped at both ends in the width direction, the x-axis carriage is moved, and the workpiece is processed by the punch die. Can be applied.

  Further, there is known a plate material processing machine configured to move a plate-shaped workpiece in the x-axis direction and the y-axis direction to process the workpiece (for example, see Patent Document 2).

  More specifically, the plate material processing machine described in Patent Document 2 is movable in the y-axis direction by engaging with the first rail extending in the y-axis direction and the first rail. A y-axis carriage, a y-axis motor for driving the y-axis carriage via a rack and pinion, and extending in the x-axis direction and engaging with the y-axis carriage to form the x-axis carriage An x-axis carriage that is movable in the axial direction, an x-axis motor that drives the x-axis carriage via a rack and pinion, and a first axis provided on the x-axis carriage for gripping the workpiece And a first clamp unit including a clamp mechanism.

  In the plate material processing machine described in Patent Document 2, the second clamp unit configured similarly to the first clamp unit is connected to the x-axis and the z-axis (perpendicular to the x-axis and the y-axis). And a symmetrical plane with respect to a predetermined plane.

Then, the first clamp unit and the second clamp unit hold a workpiece having an arbitrary width at both end portions in the width direction, and move each y-axis carriage or each x-axis carriage. Thus, the workpiece can be processed.
JP-A-9-201628 US Pat. No. 4,583,719

  By the way, in the board | plate material processing machine of the said patent document 1, since it hold | grips the both ends of a workpiece | work, even if it moves at high speed, a workpiece | work is hard to deform | transform, Therefore Thus, the machining accuracy of the workpiece can be improved.

  However, in the plate material processing machine described in Patent Document 1, the x-axis carriage extends in the y-axis direction so as to engage with the first rail and the second rail. There is a problem that the intermediate portion of the shaft carriage (intermediate portion in the y-axis direction) may interfere with the punch and die and may not be processed smoothly.

  Also, in the plate material processing machine described in Patent Document 2, since the both ends of the workpiece are gripped, the workpiece is not easily deformed even when moved at high speed, and therefore the workpiece can be processed while moving at high speed. At the same time, the machining accuracy of the workpiece can be improved.

  However, in the plate material processing machine described in Patent Document 2, the first clamp mechanism of the first clamp unit is movable in the y-axis direction, and the second clamp mechanism of the second clamp unit is also y. Since it is movable in the axial direction, depending on the mode of use, there is a problem that the reference for setting the workpiece may fluctuate and it may be difficult to use, and each clamping mechanism is Since it is configured to be movable in the direction, there is a problem that the configuration is complicated.

  The present invention has been made in view of the above problems, and in a plate material processing machine for processing a plate-shaped workpiece, the workpiece can be set with a constant reference, and the workpiece is processed while moving at high speed. An object of the present invention is to provide a plate material processing machine that can improve the processing accuracy of a workpiece, can smoothly perform processing without interference between a carriage and a processing head, and has a simple configuration. .

  According to a first aspect of the present invention, there is provided a plate material processing machine for processing a plate-like workpiece, wherein the base member extends in the x-axis direction and is provided on the base, and is movable in the y-axis direction, and the y-axis A first slider that extends in the x-axis direction and is movable in the x-axis direction, and extends in the x-axis direction, and extends in the x-axis direction to the base member. A second slider that is movable in the x-axis direction, first gripping means for integrally installing the workpiece on the first slider, and the workpiece. 2 is a plate material processing machine having second gripping means for being integrally installed on the two sliders and a processing head for processing the workpiece.

  According to a second aspect of the present invention, in the plate material processing machine according to the first aspect, the first slider and the second slider move synchronously, or the first slider and the second slider. It is a plate material processing machine characterized by having a control means which switches and controls the movement mode of the 1st slider and the 2nd slider so that these sliders may move separately.

  According to a third aspect of the present invention, in the plate material processing machine according to the first or second aspect, the base members are separated from each other in the x-axis direction and extend in the y-axis direction on the upper surface of the base. Guided by at least two y-axis rails provided, and moved in the range of each y-axis rail in the y-axis direction. The first slider is formed on the upper surface of the base. Guided by a first x-axis rail provided extending in the x-axis direction, and moved in the range of the first x-axis rail in the x-axis direction. The means is means for gripping the workpiece inside the first slider in the x-axis direction, and the second slider is provided on the upper surface of the base member so as to extend in the x-axis direction. Guided by two x-axis rails The second gripping means grips the work on the inner side of the second slider in the x-axis direction, and moves within the range of the second x-axis rail in the x-axis direction. It is a plate material processing machine which is a means to do.

  According to a fourth aspect of the present invention, in the plate material processing machine according to any one of the first to third aspects, the gripping means is a lower clamp member that is movable in the z-axis direction with respect to the slider. And an upper clamp member movable with respect to the lower clamp member in order to sandwich the workpiece in cooperation with the lower clamp member.

  According to the present invention, in a plate material processing machine for processing a plate-like workpiece, the workpiece can be set with a constant reference, the workpiece can be moved at a high speed, and the machining accuracy of the workpiece can be improved. Thus, there is an effect that it is possible to provide a plate material processing machine having a simple configuration while being able to perform processing smoothly without interference between the carriage and the processing head.

  FIG. 1 is a plan view showing a schematic configuration of a laser beam machine 1 according to an embodiment of the present invention.

  The laser processing machine 1 is a device that processes a thin plate-shaped workpiece (plate material) W and includes a base 3.

  A rectangular plate-like base member 5 is provided on the upper side of the base 3. The base member 5 extends in the x-axis direction, which is one horizontal direction, and moves in the other one direction in the horizontal direction, the y-axis direction, which is a direction perpendicular to the x-axis direction. Positioning is free.

  The base member 5 is guided by at least two y-axis rails 6 which are separated from each other in the x-axis direction and extend in the y-axis direction on the upper surface of the base 3, and a ball screw (not shown) is provided. It is driven and moved by an actuator such as a base member drive motor (not shown).

  The base member 5 moves in the y-axis direction within the range of the y-axis rails 6. In other words, the base member 5 moves within a range that does not overhang from the y-axis rail 6.

  A rectangular plate-like first slider 7 is provided on the base 3. The first slider 7 is provided away from the base member 5 in the y-axis direction, extends in the x-axis direction, and is movable and positionable in the x-axis direction.

  The first slider 7 is guided by a first x-axis rail 8 extending in the x-axis direction on the upper surface of the base 3, and is driven by a first slider via a ball screw (not shown). It is driven and moved by an actuator such as a motor 9.

  The first slider 7 moves in the x-axis direction within the range of the first x-axis rail 8. That is, the first slider 7 is moved within a range in which the first x-axis rail 8 does not overhang.

  On the upper side of the base member 5, a second slider 11 formed in substantially the same shape as the first slider 7 is provided. The second slider 11 is provided so as to extend in the x-axis direction, and can be moved and positioned in the x-axis direction.

  The second slider 11 is guided by a second x-axis rail 13 provided to extend in the x-axis direction on the upper surface of the base member 5, and is driven by a second slider via a ball screw (not shown). It is driven and moved by an actuator such as a motor 15.

  The second slider moves within the range of the second x-axis rail 13 in the x-axis direction. That is, the second slider 11 moves within a range that does not overhang from the second x-axis rail 13.

  Note that the first slider 7 and the second slider are located at the same height.

  Further, the laser processing machine 1 is provided with a first gripping means 17 and a second gripping means 19. The first gripping means 17 moves the workpiece W existing between the first slider 7 and the second slider 11 in the y-axis direction on one end side of the workpiece W in the y-axis direction. The second gripping means 19 is configured to be integrated with the first slider 7 by gripping the first slider 7 and the second slider in the y-axis direction. This is means for integrally installing the workpiece W existing between the slider 11 and the second slider 11 by gripping the other end portion side of the workpiece W in the y-axis direction.

  Further, the first gripping means 17 is configured to grip the workpiece W inside the first slider 7 in the x-axis direction, and the second gripping means 19 is configured to be in the x-axis direction. The workpiece W is gripped inside the second slider 11.

  A table 21 for placing the workpiece W is provided on the base 3, and a free bear (registered trademark) and a roller are provided on the upper surface of the table 21. The workpieces W are supported by the free bayers and rollers, and the workpieces W gripped by the gripping means 17 and 19 are supported by the free bayers and rollers as the sliders 7 and 11 move. It moves in the x-axis direction. And the workpiece | work W is processed by the laser beam radiate | emitted from the laser processing head 23 mentioned later.

  When the workpiece W is gripped by the gripping means 17 and 19, the workpiece W is lifted slightly and moved away from the free bearer or roller to move the workpiece W by the free bearer or roller. Can be avoided.

  Further, as will be described in detail later, when the needle W is provided in place of the free bearer or roller and the workpiece W is gripped by the gripping means 17 and 19, the workpiece W is slightly raised for the same purpose as described above. The workpiece W must be moved away from the needle ridge.

  Further, the laser processing machine 1 is provided with a laser processing head 23 for performing laser processing on the workpiece W. The laser processing head 23 is provided on the upper side of the workpiece W between the first slider 7 and the second slider 11 in the y-axis direction. More specifically, the laser processing head 23 is supported by a gate-shaped column (not shown) provided integrally with the base 3 and guided by a linear guide bearing (not shown). It can be moved and positioned in the y-axis direction by an actuator such as a motor.

  A laser beam emitted from a laser oscillator (not shown) is received via a bend mirror (not shown), and the laser beam is irradiated from the laser processing head 23 toward the workpiece W, so that the workpiece is substantially shown by the oblique line in FIG. Laser processing can be applied to W.

  Here, the first gripping means 17 will be described in detail. It is assumed that a needle ridge 25 is provided on the table 21.

  FIG. 2 is a diagram showing a schematic configuration of the table 21 provided with the first gripping means 17, the second gripping means 19, and the needle mountain 25, and is a diagram showing the IIA-IIB arrow view of FIG.

  The first gripping means 17 includes an appropriate number of lower clamp members 27 and an appropriate number of upper clamp members 29. The lower clamp member 27 is provided on the first slider 7 so as to be positioned on the lower side of the work W, and is applied to the first slider 7 by an actuator such as a fluid pressure cylinder or a motor. The z axis is movable in the vertical direction.

  The upper clamp member 29 is provided on the lower clamp member 27, and in order to sandwich the workpiece W in cooperation with the lower clamp member 27, a fluid pressure is applied to the lower clamp member 27. It can be moved by actuators such as cylinders and motors.

  The lower clamp member 27 can be positioned and installed with respect to the first slider 7 according to the size of the workpiece W by moving in the x-axis direction.

  The second gripping means 19 is configured in the same manner as the first gripping means 17. The lower clamp member 27 can be moved and positioned with respect to the second slider 11.

  The gripping means 17 and 19 cooperate to lift the work W slightly, clamp it away from the needle ridge 25, and move the clamped work W.

  As described above, the workpiece W before processing is transported by the conveyor (conveyor provided with the needle thread 25, the conveyor constituting the table 21) provided on the base 3, and the gripping means 17, 19 The workpiece W after processing is released by the gripping means 17 and 19 and is conveyed by a conveyor (conveyor provided with a needle thread 25) provided on the base 3. It is supposed to be done.

  The needle ridge 25 is provided on the conveyor so that the lower clamp member 27 of the second gripping means 17 moves in the y-axis direction and falls when it contacts the lower clamp member 27. .

  Further, the laser beam machine 1 is provided with a control device (not shown) for controlling the entire laser beam machine 1, and the laser beam machine 1 is operated under the control of the control device. Yes.

  Then, for example, under the control of the control device, the first slider 7 and the second slider 11 move in the x-axis direction synchronously, or the first slider 7 and the second slider 11 The movement mode of the first slider and the second slider can be switched and controlled so that the slider 11 moves separately in the x-axis direction.

  When the first slider 7 and the second slider 11 move synchronously, the base member 5 is used to move the workpiece W held by the holding means 17 and 19 with respect to the workpiece W. Control is performed by the control device so as to apply a pulling force in the y-axis direction.

  Next, the operation of the laser processing machine 1 will be described.

  First, a case where the workpiece W supported by the needle ridge 25 is gripped by the gripping means 17 and 19 will be described.

  FIG. 3 is a diagram illustrating a case where the workpiece W supported by the needle ridge 25 is gripped by the gripping means 17 and 19.

  First, as shown in FIG. 2, the workpiece W is supported by the needle ridge 25, and the base member 5 and each slider are placed at positions where the workpiece W can be gripped by the gripping means 17 and 19 in the x-axis direction. 7 and 11 are located.

  Between the state shown in FIG. 2 and the state shown in FIG. 3A, the lower clamp members 27 of the gripping means 17 and 19 are in contact with the lower surface of the workpiece W or near the lower surface of the workpiece W. To rise.

  Between the state shown in FIG. 3A and the state shown in FIG. 3B, each upper clamp member 29 is rotated (translated) with respect to each lower clamp member 27. The workpiece W is gripped by the lower clamp members 27 and the upper clamp members 29.

  Between the state shown in FIG. 3 (b) and the state shown in FIG. 3 (c), the lower clamp members 27 are further raised to separate the workpiece W from the needle ridge 25, and thereafter the base Using the member 5, the tensile force in the y-axis direction is applied to the workpiece W.

  Subsequently, the sliders 7 and 11 are appropriately moved in the x-axis direction, the laser processing head 23 is appropriately moved in the y-axis direction, and the workpiece W is subjected to laser processing.

  After the laser processing on the workpiece W is completed, the gripping of the workpiece W by the gripping means 17 and 19 is released, the workpiece W is supported by the needle ridge 25, the conveyor is driven, and the workpiece W is Take it out.

  In addition, as shown in FIG. 4 (the figure explaining the case where the workpiece | work supported by the needle mountain 25 is hold | gripped by each holding means 17 and 19), the workpiece | work W is raised with each lower clamp member 27, and the needle mountain 25 is shown. After the workpiece W is completely separated from the workpiece, the upper clamp member 29 may be rotated to grip the workpiece W.

  As will be described later, when gripping separate workpieces by the gripping means 17 and 19, it is preferable to grip the workpiece by the operation shown in FIG.

  Further, when the workpiece W is long in the x-axis direction, this is an operation of holding the workpiece W by the gripping means 17 and 19, but this operation is well-known, and thus the description thereof is omitted.

  FIG. 5 is a diagram illustrating an operation of gripping the workpiece W by the gripping units 17 and 19.

  By gripping the workpiece in this way, the displacement of the workpiece W with respect to the sliders 7 and 11 due to the gripping can be suppressed, and the workpiece W can be processed with high accuracy.

  Next, the case where each of the gripping means 17 and 19 grips and processes two workpieces will be described.

  FIG. 6 is a diagram for explaining a case in which each of the gripping means 17 and 19 grips and processes two relatively small workpieces in which the workpiece does not bend.

  In the embodiment shown in FIG. 6, the sliders 7 and 11 operate separately under the control of the control device, and the first work W1 is gripped by the second gripping means 19. Then, the laser processing is finished, and the second workpiece W3 is gripped by the first gripping means 17 and subjected to laser processing.

  Thereafter, the first workpiece W1 is unloaded from the laser beam machine 1, and the next workpiece is supplied to the laser beam machine 1 and is gripped by the second gripping means 19.

  Then, after the processing of the second workpiece W is finished, laser processing of the next workpiece (the workpiece gripped by the second gripping means 19) is started, and the second workpiece W3 is laser processed. It is carried out from the machine 1.

  According to the laser processing machine 1, the work W is gripped by the first gripping means 17 provided on the first slider 7 that does not move in the y-axis direction. Regardless of the dimension (dimension in the y-axis direction), the position of the end face in the y-axis direction (working reference) can be kept constant and the workpiece W can be installed and processed in the laser processing machine 1. Improved usability.

  Further, as shown in FIG. 7 (a diagram showing a deformed state of the workpiece when the workpiece is moved), the workpiece W is not moved by gripping only one end side of the workpiece W in the y-axis direction. Since the first gripping means 17 and the second gripping means 19 can grip both ends of the workpiece W in the y-axis direction and move the workpiece W in the x-axis direction, the workpiece W is accelerated with a large acceleration. Even if the workpiece is decelerated, the workpiece W is not easily deformed as shown by a two-dot chain line in FIG. 7, so that the workpiece W can be moved and processed at a high speed, and the fluctuation of the workpiece W during high-speed movement can be suppressed. It is possible to improve the machining accuracy of the workpiece W. In particular, according to cantilever holding, the thinner the workpiece W is bent, the more the side that is not held is bent, and the machining accuracy is lowered. Therefore, the effects of the high-speed machining and the machining accuracy improvement become remarkable.

  Moreover, since the fluttering of the workpiece W can be suppressed, it is possible to suppress the generation of noise when the workpiece W is moved and processed by being supported by a free carrier or a roller.

  In addition, since the first slider 7 and the second slider 11 are not connected to each other and are formed of separate members, the sliders 7 and 11 are also capable of performing the laser processing even while the workpiece W is being processed. There is no interference with the head 23 or the laser beam, and therefore the workpiece W can be processed smoothly.

  In addition, since only the second slider 11 is movable in the y-axis direction and the first slider 7 is configured not to move in the y-axis direction, the first slider 7 is moved to the y-axis. It is not necessary to provide a mechanism for moving in the axial direction, and the overall configuration is simplified.

  Further, according to the laser processing machine 1, when processing the workpiece W, the laser processing head 23 and the sliders 7 and 11 may be moved, and the base member supporting the second slider 11. Since it is not necessary to move 5, the mass of the portion that moves during machining can be reduced, and the workpiece W can be further processed at high speed.

  Furthermore, according to the laser processing machine 1, the first slider 7 and the second slider 11 move in synchronization, or the first slider 7 and the second slider 11 move separately. Thus, since the movement of the first slider 7 and the second slider 11 is controlled, one slider is held at both ends and the sliders 7 and 11 are synchronized. Switching between a moving machining mode and a machining mode in which the sliders 7 and 11 move separately by gripping the end portions of two relatively small workpieces that do not bend the workpiece with the gripping means 17 and 19. Thus, the laser processing machine 1 can be used, and appropriate processing can be performed in accordance with the form of the workpiece and the mode of processing.

  In the machining mode in which the first slider 7 and the second slider 11 move in synchronization by holding one workpiece at both ends, the workpiece can be machined at high speed and with high accuracy. In the machining mode in which the first slider 7 and the second slider 11 are moved separately by gripping the end portions of the two workpieces by the gripping means 17 and 19, during the machining of one workpiece. The other workpiece can be set up (installed in the laser beam machine 1 and unloaded from the laser beam machine 1), and the workpiece can be efficiently processed.

  Further, according to the laser processing machine 1, when the first slider 7 and the second slider 11 move in synchronization, the workpiece gripped by the gripping means 17 and 19 is moved in the y-axis direction. Since a tensile force is applied, the workpiece can be prevented from being bent by its own weight or the like, and processing with higher accuracy can be performed.

  Further, since the base member 5 is used to apply a tensile force to the workpiece in the y-axis direction, even if the tensile force is applied, the processing standard of the workpiece W (provided on the first slider 7). It is easy to keep the position of the part on the one end side of the workpiece W held by the first holding means 17 constant.

  Further, according to the laser processing machine 1, the base member 5 moves from the y-axis rail 6 in a range that does not overhang, and the sliders 7 and 11 move from the x-axis rails 8 and 13. Since the gripping means 17 and 19 are configured to grip the workpiece inside the sliders 7 and 11 in the x-axis direction, the workpiece is moved within a range that does not overhang. The workpieces gripped by the gripping means 17 and 19 can be moved and processed with high accuracy.

  Further, according to the laser processing machine 1, the gripping means 17 and 19 include the lower clamp members 27 that are movable in the z-axis direction with respect to the sliders 7 and 11. It can be gripped and moved while being separated from the table 21 upward. And when the workpiece | work W is moved, it can prevent that the bottom surface of the workpiece | work W is damaged.

  In the above embodiment, the laser processing machine has been described as an example. However, a plate material processing machine other than the laser processing machine, for example, a punch processing machine that processes a material with a punch and a die, a laser beam, a punch and a die. The processing machine according to the embodiment can also be applied to a composite processing machine or the like that can process a material by the above.

It is a top view showing a schematic structure of a laser beam machine concerning an embodiment of the present invention. It is a figure which shows schematic structure of the table provided with the 1st holding means, the 2nd holding means, and a needle thread, and is a figure which shows the IIA-IIB arrow view of FIG. It is a figure explaining the case where the workpiece | work supported by the needle thread is hold | gripped with each holding means. It is a figure explaining the case where each workpiece | work holding means hold | grips the workpiece | work supported by the needle thread. It is a figure which shows the operation | movement which grips the workpiece | work with each holding means. It is a figure explaining the case where the comparatively small 2 workpiece | work which does not generate | occur | produce a workpiece | work by each holding means is hold | gripped, and it processes. It is a figure which shows the deformation | transformation state of the workpiece | work at the time of a workpiece | work movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing machine 5 Base member 7 1st slider 11 2nd slider 17 1st holding means 19 2nd holding means 23 Laser processing head 27 Upper clamp member 29 Lower clamp member

Claims (4)

In a plate material processing machine that processes plate-like workpieces,
a base member extending in the x-axis direction and provided on the base and movable in the y-axis direction;
A first slider which is provided on the base and which is separated from the base member in the y-axis direction, extends in the x-axis direction, and is movable in the x-axis direction;
A second slider extending in the x-axis direction and provided on the base member and movable in the x-axis direction;
First gripping means for integrally installing the workpiece on the first slider;
Second gripping means for integrally installing the workpiece on the second slider;
A machining head for machining the workpiece;
A plate material processing machine characterized by comprising: In the board | plate material processing machine of Claim 1,
The first slider and the second slider move in synchronization with each other, or so that the first slider and the second slider move separately. A plate material processing machine comprising control means for switching and controlling a movement mode with the slider. In the board | plate material processing machine of Claim 1 or Claim 2,
The base member is guided by at least two y-axis rails that are separated from each other in the x-axis direction and extend in the y-axis direction on the upper surface of the base, and each y-axis in the y-axis direction. It moves within the range of the rail,
The first slider is guided by a first x-axis rail provided to extend in the x-axis direction on the upper surface of the base, and within the range of the first x-axis rail in the x-axis direction. It is supposed to move,
The first gripping means is a means for gripping the workpiece inside the first slider in the x-axis direction,
The second slider is guided by a second x-axis rail provided extending in the x-axis direction on the upper surface of the base member, and within the range of the second x-axis rail in the x-axis direction. It is supposed to move,
The plate material processing machine, wherein the second gripping means is a means for gripping the workpiece inside the second slider in the x-axis direction. In the board | plate material processing machine of any one of Claims 1-3,
The gripping means is
A lower clamp member movable in the z-axis direction with respect to the slider;
A plate material processing machine comprising: an upper clamp member that is movable with respect to the lower clamp member in order to sandwich the workpiece in cooperation with the lower clamp member.

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