JP3710875B2 - Positioning control method in servo mechanism, positioning control method of bending machine, and positioning control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positioning control method for a servo mechanism, a positioning control method for a bending machine, and a positioning control device.
[0002]
[Prior art]
In a conventional bending machine, a lower frame attached to a base is provided with an upper frame that can be opened and closed up and down via a pivot shaft, and a lower support member provided on the front surface of the lower frame. A receiving die is provided at the upper end of the. A presser die is provided at the lower end of the upper support member provided on the front surface of the upper frame.
[0003]
In addition, the lower end of the arcuate support is rotatably connected to the lower part of the lower frame, and the upper end of the arcuate support is rotated to the upper surface of the front part of the upper frame via a crankshaft that is driven to rotate by a servo motor. It is connected freely.
[0004]
Therefore, when the servo motor rotates the crankshaft, the upper frame rises when the bow support pivots downward, the presser mold separates from the receiving mold, and when the bow support pivots upward, the upper frame Descends and the presser mold approaches the receiving mold to clamp the workpiece.
[0005]
Referring to FIG. 8, in such a bending machine, the relationship between the command pulse value of the servo motor and the height of the presser mold is such that the upper frame is attached to the servo motor via the crank shaft, which is an eccentric shaft. Since it is opened and closed, the reduction ratio becomes large in the vicinity of the bottom dead center where the workpiece is clamped. In addition, the opening / closing motion is performed so that the reduction ratio becomes small at the intermediate position and again becomes large near the top dead center.
[0006]
This means that the shaft-converted load inertia and the load torque both decrease near the bottom dead center, and both the shaft-converted load inertia and the load torque increase at the intermediate position.
[0007]
Here, when positioning, if the shaft-converted load inertia is small, a high-speed response is possible, and conversely, if the shaft-converted load inertia is large, the response is poor. When changing, it is necessary to adjust the parameters of the servo mechanism at the position where the axis conversion load inertia is the maximum.
[0008]
[Problems to be solved by the invention]
However, in such a conventional technique, as shown in FIG. 9, there is only one kind of position gain that is a parameter of the servo mechanism, and the axis conversion load inertia is adjusted at the maximum position. Even in the vicinity of the bottom dead center where the response can be made faster, the positioning is performed with a lowered response, which hinders the increase in tact time of the entire bending machine.
[0009]
That is, as shown in FIG. 10B, the case of the so-called “pick-up” operation performed when the workpiece is replaced and the next bending process is performed is also shown in FIG. Therefore, the same parameters as in the case of an operation involving a long distance movement must be used, resulting in a problem that work efficiency is poor.
[0010]
The object of the present invention has been made by paying attention to the conventional techniques as described above, and positioning control in a servo mechanism that enables smooth and efficient positioning by changing parameters of the servo mechanism. It is an object to provide a method, a positioning control method for a bending machine, and a positioning control device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that an upper frame, which is provided so as to be rotatable with respect to the lower frame, is opened and closed via a crankshaft that is driven to rotate by a servo motor. A method of controlling a bending machine for positioning a presser mold provided, wherein the control step of controlling the servo motor estimates an axial equivalent load inertia of an upper frame corresponding to the position of the presser mold An inertia estimation step and a position gain setting step for setting a position gain in accordance with the estimated inertia, and the position gain setting step has a large shaft-converted load inertia corresponding to the opening and closing of the upper frame. A bending that includes a process that lowers the position gain and sometimes increases the position gain when the axis-converted load inertia is small Machine is a positioning control method.
[0012]
The invention according to claim 2 is the positioning control of the bending machine according to claim 1, wherein the position gain is increased by a predetermined amount in the vicinity of the bottom dead center of the presser mold before the workpiece is replaced and the next bending process is performed. Is the method .
[0013]
The invention according to claim 3 opens and closes the upper frame provided rotatably with respect to the lower frame via a crankshaft that is rotationally driven by a servo motor, and positions the presser die provided on the upper frame. A bending machine that performs control, and a control device that controls the servo motor is configured to estimate an axial conversion load inertia of the upper frame corresponding to the position of the presser mold, and to respond to the estimated inertia A position gain setting unit for setting a position gain, wherein the position gain setting unit lowers the position gain when the axis-converted load inertia is large and corresponds to the opening and closing of the upper frame, and when the axis-converted load inertia is small This is a positioning control device for a bending machine that performs control to increase the position gain .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 7 shows a conventional bending machine 1 that is very common. Since the structure and operation of the bending machine 1 are already well known, only the outline will be described.
[0016]
The bending machine 1 includes a lower frame 5 attached to a base 3 and an upper part as a moving body that is provided at the rear end portion of the upper surface of the lower frame 5 so as to be opened and closed up and down via a pivot shaft 7. A frame 9 is provided.
[0017]
A lower support member 11 is integrally provided on the front surface of the lower frame 5, and a receiving mold 13 is provided on an upper end portion of the lower support member 11. An upper support member 15 is provided on the front surface of the upper frame 9, and a presser die 17 is provided on the lower end portion of the upper support member 15.
[0018]
A lower end portion of an arcuate support rod 19 is connected to a lower portion of the front portion of the lower frame 5 by a crank pin 21 so as to be rotatable. Further, the upper end of the arcuate support 19 rotates through a connecting pin 25 to a crankshaft 23 that is rotationally driven and controlled by a servo motor SM (see FIG. 1) provided on the upper surface of the upper portion of the upper frame 9. It is connected freely.
[0019]
With the above configuration, when the servo motor SM rotates the crankshaft 23 by the control device 27 (see FIG. 1), the arcuate support rod 19 rotates and opens and closes with the crankpin 21 as a fulcrum (the solid line in FIG. 7 and State indicated by a two-dot chain line).
[0020]
Accordingly, when the bow support 19 is turned downward, the upper frame 9 is lifted, so that the presser mold 17 is separated from the receiving mold 13, and when the bow support 19 is turned upward, the upper frame 9 is lowered. The presser mold 17 approaches the receiving mold 13 and clamps the work W.
[0021]
FIG. 1 shows the configuration of the control device 27. The control device 27 includes a positioning main module 29 and a position control unit 31 inside. Furthermore, the position control unit 31 includes, for example, a position command unit 33 that issues a command pulse in accordance with a stored positioning pattern, and a position gain automatic adjustment unit 35 that automatically adjusts the position gain.
[0022]
In the position gain automatic adjustment unit 35, a command current position setting unit 37 is connected to the position command unit 33, and an inertia estimation unit 41 for estimating the inertia at the inertia determination position stored in the memory 39A is connected to the memory 39B. A position gain setting unit 43 for setting the position gain according to the parameters stored in is connected.
[0023]
The position command unit 33 is also connected to the comparison circuit 45, and the servo amplifier 47 is controlled by the servo amplifier 47 using the position gain set by the position gain setting unit 43. The servo motor SM is provided with an encoder 49, and the servo mechanism is configured by feeding back the position measured by the encoder 49 to the comparison circuit 45.
[0024]
Next, the operation of such a control device 27 will be described.
[0025]
The positioning main module 29 issues a positioning command to the position command unit 33 of the position control unit 31 and issues a position gain automatic adjustment command to the position gain automatic adjustment unit 35.
[0026]
In the position gain automatic adjustment unit 35, the command current position setting unit 37 sets the command current position at a certain interval (see FIG. 2) according to the positioning pattern from the position command unit 33, and the inertia estimation unit 41 estimates the axis-converted load inertia. To do. The position gain setting unit 43 sets a position gain corresponding to the estimated axis conversion load inertia as a parameter. This operation is performed until the positioning is completed.
[0027]
As a method of setting the position gain by estimating the shaft-converted load inertia from the current position of the presser mold 17, there is a method of using a table as shown in FIG. 3, for example.
[0028]
With reference to FIG. 4, the procedure for setting the position gain will be described. Since the position gain cannot be set in advance, start (step SS), monitor the current position, and then determine whether the current position gain is G1 corresponding to the region A in FIG. 2 (step S1). If it is G1, it is determined whether or not the current position is equal to or greater than X1 pulse (step S2). If the current position is equal to or smaller than X1 pulse, that is, in the area A, the position gain is determined as G1 and the process ends. (Step SE).
[0029]
On the other hand, if the current position is larger than the X1 pulse, it is determined that the current position is in the region B, the position gain is set to G2 (step S3), and the process ends (see step SE, FIG. 5).
[0030]
If it is determined in step S1 that the position gain is not G1, it is determined whether or not it is G2 (step S4). If it is G2, it is determined whether or not the current position is less than or equal to the X1 pulse. (Step S5) If the current position is equal to or less than the X1 pulse, that is, in the region A, the position gain is set to G1 (Step S6), and the process ends (Step SE).
[0031]
On the other hand, if it is determined in step S5 that the current position is greater than the X1 pulse, it is determined whether or not the current position is greater than or equal to the X2 pulse (step S7). The position gain is set to G2 as it is in B, but if it is determined that the position gain is equal to or greater than X2, the position gain is set to G3 (step S8) and the process ends (see step SE, FIG. 5).
[0032]
If it is determined in step S4 that the position gain is not G2, it is determined whether it is G3 (step S9). If it is G3, it is determined whether the current position is equal to or less than the X2 pulse. (Step S10) If the current position is equal to or less than the X2 pulse, that is, in the region B, the position gain is set to G2 (Step S11), and the process ends (Step SE).
[0033]
On the other hand, if it is determined in step S10 that the current position is larger than the X2 pulse, it is determined whether or not the current position is greater than or equal to the X3 pulse (step S12). If it is determined that the position gain is C, the position gain is set to G3 as it is. If it is determined that the position gain is equal to or greater than X3, the position gain is set to G4 (step S13) and the process ends (step SE, see FIG. 5).
[0034]
Further, if it is determined in step S9 that the position gain is not G3, it is determined whether or not the current position is X3 or less (step S14), and if it is X3 or more, it is determined that the current position is in region D. The position gain remains G4 and ends (step SE).
[0035]
On the other hand, if the current position is X3 or less, it is determined that the current position is in the region C, the position gain is set to G3 (step S15), and the process ends (see step SE, FIG. 5).
[0036]
From the above results, as shown in FIG. 6A, the position gain can be lowered when the shaft-converted load inertia is large and the position gain can be increased when the shaft-converted load inertia is small. You can plan up.
[0037]
Further, since the position gain in the vicinity of the bottom dead center of the presser die 17 can be increased, as shown in FIG. 6B, the predetermined amount is increased when the workpiece W is replaced and the next bending process is performed. The presser mold 17 can be quickly moved during the operation (so-called “choking”), and the tact time can be greatly increased.
[0038]
The present invention is not limited to the above-described embodiment, and can be implemented in other modes by making appropriate modifications.
[0039]
【The invention's effect】
As described above, the position gain can be set according to the axis-converted load inertia of the moving body, so when the inertia is large, the position gain is decreased, and when the inertia is small, the position gain is increased. Tact up can be achieved. For this reason, the efficiency of the positioning operation can be improved.
[0040]
In addition, the position gain can be set according to the axial conversion load inertia of the upper frame equipped with the presser die , so that the position gain is decreased when the inertia is large, and the position gain is increased when the inertia is small. By doing so, tact-up can be achieved. For this reason, it is possible to increase the tact by increasing the position gain at the time of so-called “pick-up” operation performed near the bottom dead center in order to replace the workpiece in the bending machine.
[0041]
When the workpiece is clamped by the presser mold and the receiving mold by rotating the crankshaft by the servo motor controlled by the control apparatus and opening and closing the upper frame, the inertia estimation unit of the control apparatus The axis-converted load inertia of the upper frame corresponding to the position is estimated, and the position gain setting unit sets the position gain corresponding to the estimated inertia and controls the servo motor. Therefore, if the inertia is large, the position gain is If the inertia is small and the inertia is small, the position gain can be increased to increase the tact time. For this reason, it is possible to increase the tact by increasing the position gain at the time of so-called “pick-up” operation performed near the bottom dead center in order to replace the workpiece in the bending machine.
[0042]
Furthermore, a preset positioning operation can be quickly performed, and the bending machine can be tact-uped.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram showing a configuration of a positioning control device of a bending machine to which a positioning control method according to the present invention is applied.
FIG. 2 is a graph showing the relationship between the position of a presser mold and the number of pulses of a servo motor.
FIG. 3 is a table showing inertia and position gain corresponding to each region shown in FIG. 2;
FIG. 4 is a flowchart showing a procedure for determining a position gain in the positioning control method according to the present invention.
FIG. 5 is a graph showing the position gain for each region shown in FIG. 2;
FIG. 6 is a graph showing a change in position gain for an operation with a large movement distance and an operation with a small movement distance.
FIG. 7 is a side view showing the entire bending machine.
FIG. 8 is a graph showing the relationship between the position of the presser mold and the number of pulses of the servo motor.
FIG. 9 is a graph showing a position gain in positioning in a conventional bending machine.
FIG. 10 is a graph showing a position gain state for a conventional operation with a large moving distance and an operation with a small moving distance.
[Explanation of symbols]
1 Bending machine 5 Lower frame 9 Upper frame (moving body)
13 Receiving Die 17 Presser Die 23 Crankshaft 27 Controller 41 Inertia Estimation Unit 43 Position Gain Setting Unit SM Servo Motor

Claims (3)

A control method for a bending machine that opens and closes an upper frame provided rotatably with respect to the lower frame via a crankshaft that is rotationally driven by a servo motor and positions a presser die provided on the upper frame. Because
  The control process for controlling the servo motor includes an inertia estimation process for estimating an axis-converted load inertia of the upper frame corresponding to the position of the presser mold, and a position gain setting for setting a position gain according to the estimated inertia A process,
  The position gain setting step includes a step of lowering the position gain when the shaft-converted load inertia is large and increasing the position gain when the shaft-converted load inertia is small, corresponding to the opening and closing of the upper frame. A positioning control method for a processing machine. 2. The positioning control method for a bending machine according to claim 1, wherein the position gain is increased by a predetermined amount in the vicinity of the bottom dead center of the presser mold before the workpiece is replaced and the next bending process is performed. A bending machine that opens and closes an upper frame that is rotatably provided with respect to a lower frame via a crankshaft that is rotationally driven by a servo motor, and positions a presser die that is provided on the upper frame. ,
  A control device that controls the servo motor, an inertia estimation unit that estimates an axis-converted load inertia of the upper frame corresponding to the position of the presser mold, and a position gain setting that sets a position gain according to the estimated inertia With
  The position gain setting unit performs a control corresponding to the opening / closing of the upper frame to lower the position gain when the axis-converted load inertia is large and to increase the position gain when the axis-converted load inertia is small Positioning control device for processing machines.

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