JP2015229176A - Work follow-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work follow-up device capable of measuring a spring-back precisely in accordance with the motion of a work and capable of supporting the workpiece stably at all times.SOLUTION: In a work follow-up device 10 including a tracking table 20 disposed adjacent to a press brake 1 for supporting a plate-shaped work W bent by the press brake 1, while following the lift of the work W, the tracking table 20 is equipped with a load sensor 30 for detecting a load to act on the placing face of said tracking table 20, so that a control device 50 causes the position of the tracking table 20 to follow the work W on the basis of the signal of that load sensor 30.

Description

  The present invention relates to a workpiece follower that is provided adjacent to a press brake and supports a workpiece while following up of the workpiece during bending of a plate-like workpiece.

  The press brake has a die having a V-groove and a punch that moves up and down relatively with respect to the die, and applies pressure to the plate-shaped workpiece placed on the die by lowering the punch or raising the die. In addition, the workpiece is bent.

  For example, when a large plate-shaped workpiece is bent into a V shape by this press brake, the other part of the workpiece is lifted as the portion sandwiched between the punch and the die is deformed, and the raised portion is not properly supported. In some cases, the dead weight may cause unnecessary deformation in the workpiece itself.

  In order to prevent this, conventionally, as shown in FIG. 6, a follower is provided on the front side of the press brake, and the inclination angle θ of the follower table 120 of the follower is lifted according to the bending process by the punch 5 and the die 6. The work W is supported while following the bending angle of W.

  Further, in the processing by the press brake, as shown in FIG. 7A, the workpiece W is bent by relatively lowering the punch 5 toward the die 6, but the punch 5 is raised after the bending processing. It is known that when unloaded (separated from the die 6), the workpiece W is opened more than the bent angle as indicated by the symbol Wa due to the spring back. Accordingly, the spring back amount α is accurately measured by trial processing, and the main processing is performed at a bending angle that allows for the spring back amount.

  As an example of the conventional tracking device described above, for example, the one described in Patent Document 1 is known. In this tracking device, as shown in a simplified manner in FIG. 8, a contact sensor (work detection sensor) 135 is incorporated in the tracking table 130, and the contact sensor 135 determines whether or not the workpiece W is separated from the table 130. The gap amount between the table 130 and the workpiece W generated by this is detected, and based on the detection result, the tracking table 130 is made to follow the lifting of the workpiece W so that the gap amount falls within a predetermined range.

  That is, in this tracking device, when the work W is separated from the table 130, the table 130 performs a chasing operation, and the tracking speed of the table 130 is changed according to the gap amount between the work W and the table 130. Specifically, the follow-up speed is increased when the gap amount is increased, and the follow-up speed is decreased when the gap amount is decreased. Control is performed so that the gap amount becomes zero.

  However, in this follow-up device, there is a problem in that the spring back amount cannot be accurately measured because the table 130 does not move backward in the in-line mode in which bending is performed while measuring the bending angle with a bending indicator (bending angle measuring device). there were.

  As another example of a conventional tracking device, there is a tracking device that detects the position of the ram that pressurizes the punch or die with an encoder and determines the tracking position of the tracking table according to the position of the ram. .

  In this follow-up device, the ram is moved to the pinching point, and then the follow-up table can be moved forward and backward in accordance with the vertical movement of the ram, so that the spring bag can be accurately measured in the in-line mode.

  However, as shown in FIG. 9, there are the following problems when the bending load is large, such as when bending a thick workpiece W. That is, as shown in FIG. 9A, when bending is performed by applying a pressing force A from above, bending is performed while a lower table (not shown) supporting the die 6 is bent downward.

  Therefore, after bending, as shown in FIG. 9B, the workpiece 5 remains pressed by the punch 5 until the ram rises by the dimension H and the bending of the lower table is eliminated. Since the die 6 and the workpiece W are displaced upward together, there is a time when the workpiece W does not fall by springback (the angle does not change). As a result, a gap is formed between the workpiece W and the tracking table 140, and then the workpiece W is moved back by the spring back when the ram rises a little more and the bending of the lower table is eliminated and the punch 5 is not pressed. There is a risk of falling down while making an impact sound on the 140 side.

JP 2003-126913 A

  As described above, in the case of a tracking device that performs control to synchronize the tracking operation of the tracking table 140 with the movement of the ram, as shown in FIG. 9B, there is a time zone during which the tracking table 140 moves away from the workpiece W. During this time, there was a risk that stable support of the workpiece could not be achieved.

  In view of the above circumstances, an object of the present invention is to provide a workpiece follower that can accurately measure the springback in accordance with the movement of the workpiece and can always stably support the workpiece.

  In order to solve the above-described problem, the workpiece follower of the invention of claim 1 is a workpiece follower including a follower table that supports a workpiece while following the lifting of a plate-like workpiece bent by a press brake. A control device for providing a load sensor for detecting a load acting on the mounting surface of the tracking table on the tracking table, and causing the position of the tracking table to track the workpiece based on a signal of the load sensor. It is characterized by having prepared.

  A workpiece follower according to a second aspect of the present invention is the workpiece follower according to the first aspect, wherein the control device determines a threshold value determined according to an inclination angle of the follower table and a detection value of the load sensor. And the tracking speed of the tracking table is controlled based on the comparison result.

  A workpiece follower according to a third aspect of the present invention is the workpiece follower according to the second aspect, wherein a dead zone is set in the threshold value, and the detection value of the load sensor is set in the threshold value in the control device. When the dead zone is exceeded, the follow-up speed is controlled to be slowed down, and when the detection value of the load sensor is below the dead zone set in the threshold value, the follow-up speed is controlled to be fastened. It is a feature.

  According to the first aspect of the present invention, the tracking table can be made to follow the workpiece so as not to be separated from the workpiece, and the workpiece can be stably and reliably supported by the tracking table. In addition, when the follower table is pushed above a certain load, the follower table can escape so as not to leave the workpiece, so that the workpiece can always be supported by the follower table. Therefore, the spring back can be accurately measured in accordance with the movement of the workpiece. Also, when a workpiece with a large thickness is bent, even if the punch (ram) rises until the bending of the lower table during the bending process is eliminated, the workpiece is spring-backed on the follower table. Although there is a time zone during which the robot does not fall down, it can be controlled so that there is no gap between the tracking table and the workpiece, and the workpiece can always be supported stably by the tracking table.

  According to the invention of claim 2, since the detection value of the load sensor is compared with a threshold value that changes in accordance with the inclination angle of the tracking table, the workpiece can be properly supported regardless of the inclination angle of the tracking table. .

  According to the invention of claim 3, since the dead zone is set in the threshold value, fluttering of the control operation can be suppressed.

It is a side view which shows the state at the time of the bending start of the tracking apparatus of embodiment of this invention. It is an enlarged view of the principal part of FIG. It is a side view which shows the state at the time of the bending process completion | finish of the tracking apparatus. It is an enlarged view of the principal part of FIG. It is an expanded sectional view showing the state at the time of the end of bending when a workpiece having a large plate thickness is bent by the follower. It is explanatory drawing of a prior art example. It is explanatory drawing of a prior art example, (a) is a figure which shows the state at the time of completion | finish of a bending process, (b) is a figure which shows the state at the time of spring bag release after a bending process. It is a figure which shows an example of the conventional tracking apparatus. It is explanatory drawing of the problem of another conventional follower, (a) is a figure which shows the state at the time of completion | finish of a bending process, (b) is a figure which shows a state until a ram raises and the bending of a lower table is eliminated. It is.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing the state of the follower of the embodiment at the time of starting the bending process, FIG. 2 is an enlarged view of the main part thereof, FIG. 3 is a side view showing the state at the end of the bending process, and FIG. FIG.

  As shown in FIGS. 1 to 4, the follower 10 of the embodiment is disposed adjacent to the front side of the press brake 1.

  In the press brake 1, an upper table 2 having a punch 5 attached to the lower end thereof is arranged on the upper side of a C-shaped side frame 9 so that it can be moved up and down by a lifting device (not shown). The plate-like workpiece W placed on the die 6 is moved in cooperation with the punch 5 and the die 6 by moving the lower table 4 fixedly and lowering the upper table 2 by operating the lifting device. It is to be bent.

  The follower 10 rotates the follower table 20 on which the work W to be bent by the press brake 1 is placed in accordance with the lifting of the work W by bending. A support member 11 and a support mechanism 12 that rotatably support the tracking table 20 around a predetermined position corresponding to a bent portion, and a servo motor that rotates the tracking table 20 via the support member 11 and the support mechanism 12. 15 and a control device 50 that drives the servo motor 15 to cause the follow-up table 20 to follow the workpiece W.

  In this case, the tracking table 20 includes a table main body 21 fixed to the support member 11, a sensor table 22 movable with respect to the table main body 21, and a direction perpendicular to the workpiece placement surface of the sensor table 22. And a load sensor 30 for detecting the acting load.

  The sensor table 22 can be displaced only in a direction perpendicular to the workpiece placement surface with respect to the table body 21, and the load sensor 30 applies a load in a direction perpendicular to the workpiece placement surface acting on the sensor table 22. The measurement data is input to the control device 50.

  Based on the signal from the load sensor 30, the control device 50 controls the servo motor 15 so that the position of the tracking table 20 follows the movement of the workpiece W. Here, the control device 50 compares the threshold value determined according to the inclination angle θ of the tracking table 20 (see FIG. 3) with the detection value of the load sensor 30, and based on the comparison result, Control the tracking speed.

  For example, a dead zone is set to a threshold value determined according to the inclination angle θ of the tracking table 20. And the control apparatus 50 controls in the direction which makes a follow-up speed slow when the detection value of the load sensor 30 exceeds the dead zone set to the threshold value, and follows when the detection value of the load sensor 30 falls below the dead zone set to the threshold value. Control the direction to increase the speed.

  Actually, the detection data of the load sensor 30 for each inclination angle θ of the tracking table 20 when “the load Wa of the workpiece W + the load Wb of the tracking table 20” is applied to the load sensor 30 is collected. However, at this time, measurement is performed with only the workpieces W and the own weights Wa and Wb of the tracking table 20 acting on the load sensor 30.

  A value [≈ (Wa + Wb) cosθ] for each inclination angle θ is set as a threshold value Wθ and is stored in a database. In addition, the dead range (dead zone) is set to a range of ± α% with respect to the threshold (for example, α% = 5%). By doing so, the follow-up speed of the follow-up table 20 is controlled as follows by comparing the detection values Ws and Wθ of the load sensor 30.

  (1) When Ws <Wθ × (1−α / 100), it is considered that the follow-up table 20 does not support the workpiece W, so that the detection value Ws of the load sensor 30 falls within the following range (2). Increase the follow-up speed to enter.

  (2) When W.theta..times. (1-.alpha./100) .ltoreq.Ws.ltoreq.W.theta..times. (1 + .alpha. / 100), it is considered that the tracking table 20 appropriately supports the workpiece W, so that the tracking speed is maintained.

  (3) When Wθ × (1 + α / 100) <Ws, it is considered that the follow-up table 20 is pushing up the workpiece W, so that the detection value Wθ of the load sensor 30 falls within the range of (2). Decrease the follow-up speed.

  By performing the control as described above, the tracking table 20 can be made to follow the workpiece W so as not to leave the workpiece W, and the workpiece W can be supported by the tracking table 20 stably and reliably. In addition, when the tracking table 20 is pushed with a certain load or more, the tracking table 20 can escape so as not to be separated from the workpiece W, so that the workpiece W can always be supported by the tracking table 20. Therefore, the springback can be accurately measured in accordance with the movement of the workpiece W.

  Further, as shown in FIG. 5, when a workpiece W having a large thickness is bent, even if the punch 5 (ram) rises until the bending of the lower table is eliminated during bending, the workpiece There is a time zone in which W does not fall on the tracking table 20 due to the spring back, and at that time, control can be performed so that there is no gap between the tracking table 20 and the workpiece W. Accordingly, the workpiece W can be supported by the tracking table 20 stably at all times.

  In particular, since the detection value Ws of the load sensor 20 is compared with a threshold value Wθ that changes in accordance with the inclination angle θ of the tracking table 20, the workpiece W is appropriately transferred by the tracking table 20 regardless of the inclination angle θ of the tracking table 20. Can be supported. In addition, since the dead zone ± α% is set as the threshold value Wθ, it is possible to suppress the fluttering of the control operation.

1 Press brake 10 Work following device 20 Follow table 30 Load sensor 50 Control device W Work

Claims (3)

In the workpiece follower equipped with a follower table that supports the workpiece while following the lifting of the plate-like workpiece bent by the press brake,
A control device for providing a load sensor for detecting a load acting on the mounting surface of the tracking table on the tracking table, and causing the position of the tracking table to track the workpiece based on a signal of the load sensor. A workpiece following device characterized by comprising. The workpiece following device according to claim 1,
The control device is configured to compare a threshold value determined according to an inclination angle of the tracking table with a detection value of the load sensor, and control the tracking speed of the tracking table based on the comparison result. Work following device characterized by The workpiece following device according to claim 2,
A dead zone is set in the threshold value, and the control device controls the direction of slowing the follow-up speed when the detected value of the load sensor exceeds the dead zone set in the threshold value, and the detected value of the load sensor is A workpiece follower configured to control in a direction to increase the follow-up speed when it falls below a dead zone set as the threshold value.

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