JP3969850B2 - Control method and control device for electric vendor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling an electric vendor in which a plate material is bent by an upper mold mounted on a ram having three or more drive shafts driven by an electric motor and a lower mold mounted on a fixed table. And a control device.
[0002]
[Prior art]
Conventionally, a ram (movable table) is driven by an electric motor, and a plate material is bent by an upper mold mounted on the ram and a lower mold mounted on a fixed table arranged opposite to the ram. Formula vendors are known.
[0003]
In this type of electric bender, a plurality of servo axes (generally referred to as “DS axes”) for controlling the positioning of the ram in the vertical direction are provided except for a vendor with extremely small pressurizing capacity. It is common. The ram is moved up and down via a ball screw by rotation of a ball nut connected to a motor. A linear encoder that detects the vertical position of the ram is provided corresponding to each DS axis, and the motor and the linear encoder are electrically connected to a servo control device. In this way, when the servo control device commands the target positions simultaneously to a plurality of DS axis control systems, each DS axis control system drives each DS axis toward the commanded target position, thereby positioning the ram. Done.
[0004]
In addition, there exist some which are disclosed by each following gazette as a prior art relevant to this invention.
(1) Japanese Patent Publication No. 3-67000 In a hydraulic press in which a slide is moved up and down by a plurality of hydraulic cylinders, the servo mechanism is synchronously controlled by a variable speed motor so that the same amount of flow is discharged from each hydraulic pump. In addition, a slide stroke detector is provided, the values detected by these detectors are compared, and the flow control valve is controlled by the obtained value so that the slide moves up and down in a parallel state with respect to the bolster. What you did.
(2) Japanese Utility Model Publication No. 3-76700 In a hydraulic press that moves a slide up and down by a plurality of hydraulic cylinders, the height position of each part of the slide is detected and fed back to each control system. The relative position deviation between the reference axis and other axes is calculated from the value, and the control system gain value of the axes other than the reference axis is changed in proportion to the magnitude of this relative position deviation.
(3) Japanese Patent Laid-Open No. 3-35899 relates to a synchronous control device for a hydraulic press having a plurality of hydraulic cylinders, wherein the relative position deviation between the axes is obtained from the detection value of the position detecting device provided in each cylinder. At the same time, the axis closest to the target value is discriminated, and the relative position deviation is fed back to each other axis in order to make the axis closest to the target value the reference axis and match the other axes to the reference axis. What you did.
[0005]
[Problems to be solved by the invention]
However, in the conventional ram positioning control system described above, a target position is instructed simultaneously to a plurality of DS axis control systems, but in reality, load inertia, viscous friction force applied to each DS axis, Disturbances are not equal, and each DS axis is in a mutual interference system relationship via a ram. For example, when there is a difference in the load on each DS axis, An external force (torque disturbance) is applied from the other DS axis via the ram, and a large current flows through the servo motor, an excessive force is applied to the ram itself, or the desired positioning accuracy cannot be obtained. There is a problem.
[0006]
Further, those disclosed in the above-mentioned publications cited as the prior art related to the present invention have the following problems.
(1) Japanese Patent Publication No. 3-67000 In this prior art, since a mechanical feedback composed of a variable speed motor, a mechanical link and a hydraulic pump is used, it is highly accurate under the influence of backlash and temperature change. Control is not possible. For example, when four hydraulic cylinders are used, the control system is divided into two left and right control systems, and synchronous control is performed for each group. Cannot be controlled.
(2) Japanese Utility Model Publication No. 3-76700 In this prior art, the control system becomes unstable because the gain of each axis is changed in accordance with the relative position deviation between the reference axis and the other axes. Positioning control itself may not be possible. In addition, since the relative position deviation between the axes is not directly fed back, high-precision control cannot be performed.
(3) JP-A-3-35899 In this prior art, since the axis closest to the target value is used as the reference axis, the reference axis changes from time to time until the target value is reached. The control system becomes unstable due to the hunting state near the target value.
[0007]
The present invention has been made to solve the various problems of the prior art as described above, and applies an excessive force to the ram even when there is a difference in load on each axis or there is a load fluctuation. It is an object of the present invention to provide a control method and a control apparatus for an electric vendor that can perform ram positioning control at high speed and with high accuracy.
[0008]
[Means for solving the problems and actions / effects]
In order to achieve the above object, a control method of an electric vendor according to the first invention is:
A control method of an electric vendor that performs bending of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table,
Each servo motor that drives each drive shaft outputs a speed command signal in the position control unit by a position command signal from the outside and a position feedback signal from a position detector provided corresponding to each drive shaft position. The speed control unit generates a current command signal based on the speed command signal, and the power control unit is controlled by generating an actual current for driving the servo motor based on the current command signal.
Servo motors related to other drive shafts other than a predetermined reference drive shaft among the drive shafts, the position control unit related to the other drive shaft, the other drive shaft generated in the correction control unit and the reference drive When a control signal based on a relative position deviation with respect to the shaft is input, control is performed in consideration of the relative position deviation, and the relative position between the other drive shaft and the reference drive shaft is included in the position control unit. A relative position deviation signal is input from an inter-axis position setter that sets the position to a desired value .
[0009]
In the present invention, each servo motor that drives each drive shaft is driven and controlled by a control system including a position control unit, a speed control unit, and a power control unit. In this control system, a position command signal from an external NC device, for example, is input to the position control unit of each axis, and a position feedback signal from a position detector provided corresponding to each drive shaft position is input. Based on these input signals, a speed command signal is output from each position controller to each speed controller. In each speed control unit, a current command signal is generated based on a speed command signal input from each position control unit, and this current command signal is output to each power control unit. Further, in each power control unit, an actual current for driving the servo motor is generated based on the input current command signal, and each servo motor is directly driven based on the actual current. A servo motor control system related to other drive shafts excluding the reference drive shaft is provided with a correction control unit. A relative position deviation signal between the other drive shaft and the reference drive shaft is input to the correction control unit, and a control signal based on the relative position deviation signal is output from the correction control unit to a position related to the other drive shaft. Output to the control unit. In this way, in drive shafts other than the reference axis, control for setting the deviation (self-position deviation) between the target position signal and the position feedback signal for each axis to zero and the relative position deviation with respect to the reference axis are set to zero. Therefore, even if there is a load difference between the reference axis and another drive axis, or there is a load change, the other drive axis can follow the reference axis. Disturbances (torque disturbance) from other axes entering the servo system via the ram can be suppressed. Therefore, the ram can be positioned with high speed and high accuracy without applying an excessive force to the ram.
[0010]
Further, the position control unit, the relative position deviation signal from the inter-axis position setter for setting the relative position between the other drive shaft and the reference drive shaft to a desired value has been entered, for example, the ram The relative position between the axes can be set to an arbitrary value when it is desired to add crowning.
[0011]
Next, the control device for the electric vendor according to the second invention is:
A control device for an electric vendor that performs bending processing of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table,
Each servo motor controller that drives each drive shaft receives a position command signal from the outside and a position feedback signal from a position detector provided corresponding to each drive shaft position, and outputs a speed command signal. A position control unit, a speed control unit that generates a current command signal based on the speed command signal from the position control unit, and a power control that generates an actual current for driving the servo motor based on the current command signal from the speed control unit With
Among the control devices, a control device related to another drive shaft excluding a predetermined reference drive shaft generates a control signal based on a relative position deviation between the other drive shaft and the reference drive shaft, A correction control unit that outputs to a shaft position control unit, and an inter-axis position setting device that sets a relative position between the other drive shaft and the reference drive shaft to a desired value. It is what.
[0012]
The present invention relates to a control device for more specifically realizing the control method of the electric vendor according to the first invention, and has the same operations and effects as the first invention.
[0013]
In addition, since an inter-axis position setting device is provided to set the relative position between the other drive shaft and the reference drive shaft to a desired value, the relative position between the shafts , for example, when it is desired to add crowning to the ram. Can be set to an arbitrary value by the inter-axis position setting device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, specific embodiments of an electric vendor control method and control apparatus according to the present invention will be described with reference to the drawings.
[0015]
FIG. 1 is a partial perspective view of an electric vendor according to an embodiment of the present invention.
[0016]
The electric vendor according to this embodiment includes a ram (upper movable table) 1 that is driven up and down, and a fixed table (lower fixed table) 2 that is fixedly disposed facing the ram 1. A punch (upper die) (not shown) is attached to the lower portion of the fixing table 2 via a punch holding device 3, and a die (none of which is shown) is attached to the upper surface of the fixed table 2 via a die holding device.
[0017]
A pair of side frames 5, 5 are integrally provided on both sides of the fixed table 2, and a support frame 6 is provided so as to connect the upper ends of the side frames 5, 5. A plurality of (four in this embodiment) ram driving devices 7 are attached to the support frame 6, and the ram 1 is swingably connected to the lower end of these ram driving devices 7. In this way, the ram 1 is moved up and down by the operation of the ram driving device 7, whereby the plate material (work) inserted between the punch and the die is bent.
[0018]
Each ram driving device 7 transmits an AC servo motor 8 controlled by a servo control device, which will be described later, to a ball nut (not shown) via a timing belt 9 as a driving source, and a ball screw connected to the ball nut. The ram 1 connected to the ball screw 10 is driven up and down by moving the 10 up and down.
[0019]
Incremental linear encoders 11 are attached to the rams 1 corresponding to the positions of the drive shafts of the respective ram drive devices 7 (hereinafter referred to as DS1 axis, DS2 axis, DS3 axis, DS4 axis from the left side), The detector 12 is attached to the extension correction bracket 13. The detection data from the linear encoder 11 is used for position feedback as will be described later. Here, the extension correction bracket 13 is composed of two side plates 13a, 13a provided along the side frames 5, 5, and a beam 13b connecting the left and right side plates 13a, 13a. . By attaching the detector 12 of the linear encoder 11 to the extension correction bracket 13 in this way, each linear encoder 11 is not affected by deformation due to load changes of the side frames 5 and 5, and each drive of the ram 1 is driven. The absolute position for each axis can be measured. In this embodiment, the linear encoder (main body) 11 is attached to the ram 1 and the detector 12 is attached to the correction bracket 13. However, these attachment positions may be reversed.
[0020]
Further, an absolute type motor encoder 14 (see FIG. 2) for detecting the current position of each servo motor 8 is attached to the motor shaft of each servo motor 8. The detection data from the motor encoder 14 is used for speed feedback as will be described later.
[0021]
Next, a servo control device for controlling each servo motor 8 will be described with reference to FIG.
[0022]
This servo control device includes a control system 15 for a reference axis (here, DS1 axis is a reference axis) and control systems 16, 17, 18 for the other three axes (DS2, DS3, and DS4 axes). These four control systems are configured. In FIG. 2, the detailed configurations of the control systems 17 and 18 relating to the DS3 axis and the DS4 axis are the same as those of the control system 16 relating to the DS2 axis, and thus are omitted.
[0023]
Each control system 15, 16, 17, 18 receives a position command signal (movement amount signal) from the NC device 19 and a position feedback signal from the linear encoder 11 for each drive shaft and outputs a speed command signal. A current command signal is calculated based on the speed deviation signal calculated from the difference between the position control unit 20, the speed command signal from the position control unit 20, and the speed feedback signal from the motor encoder 14, and is output. A current deviation amount signal calculated from the difference between the speed control unit 21, the current command signal output from the speed control unit 21, and the current feedback signal is input to the power control unit 23 based on this input signal. A current control unit 22 that outputs a signal for generating a current, and a power control unit 23 that directly drives the servo motor 8 based on the signal from the current control unit 22. There is a obtain configuration.
[0024]
Further, in the control systems 16 to 18 related to the other drive axes (DS2 to DS4) excluding the reference axis (DS1 axis), a correction control unit 24 and an inter-axis position setting unit 25 are provided in addition to the above configuration. . For example, the correction controller 24 in the DS2 axis control system 16 subtracts the DS2 axis position feedback signal (DS2 axis position) from the reference axis (DS1 axis) position feedback signal (DS1 axis position). A value obtained by multiplying the calculated value by a constant is output to the position control unit 20 of the DS2 axis. The DS3 axis and DS4 axis are also processed in the same manner as the DS2 axis. That is, each correction control unit 24 provided in the control systems 16 to 18 of the drive shafts (DS2 to DS4) other than the reference shaft obtains a relative position deviation between the reference shaft and the drive shaft, and the position control unit of the drive shaft. 20 is output. The inter-axis position setting unit 25 is a setting unit that sets the inter-axis position to an arbitrary value in order to bias the relative position deviation, for example, when it is desired to add crowning to the ram 1.
[0025]
FIG. 3 shows a detailed configuration of the position control unit 20 provided in the control systems 16 to 18 of the drive shafts (DS2 to DS4) other than the reference shaft.
[0026]
As shown in the figure, the movement amount signal input from the NC device 19 is input to the speed pattern generation unit 26, and the speed pattern generation unit 26 generates a speed pattern based on the preset maximum speed and acceleration / deceleration time. . Subsequently, based on the generated speed pattern, the target position converted per one execution time of the control system is sequentially calculated in the target position calculation unit 27. Further, with respect to the difference (self-position deviation) between the target position signal calculated by the target position calculation unit 27 and the position feedback signal from the linear encoder 11, the reference axis generated by the correction control unit 24 and The relative position deviations are added and output to the gain calculation unit 28 at the subsequent stage as a total position deviation amount. Thereafter, the gain calculation unit 28 multiplies the total position deviation amount by a gain constant Kp. This gain constant Kp is generally called a position loop gain, and is a parameter that determines the response and stability of the control system.
[0027]
In such a servo control device, a position command signal (the same value for all axes) output from the NC device 19 is input to the position control unit 20 of each control system 15-18, and each servo motor 8 is based on this command signal. Is driven to move the ram 1 up and down. When the ram 1 is moved up and down, the vertical position at each drive shaft position of the ram 1 is detected by the linear encoder 11 and fed back to the position controller 20 as position feedback so as to coincide with the position command signal from the NC device 19. The control system drives the servo motor 8.
[0028]
Thus, even if the target positions are commanded to a plurality of DS control systems at the same time, when there is a difference in the load on each DS axis or there is a load fluctuation during control, a relative position deviation occurs between the axes. . In the servo control device of this embodiment, such relative position deviation is constantly monitored. Specifically, the deviation (self-position deviation) between the target position signal and the position feedback signal for each axis is obtained as described above, and the relative position deviation between the reference axis and the drive axis in the DS2 axis to the DS4 axis. And the total position deviation is synthesized from these deviations. In this case, in order to determine which of the self-position deviation and the relative position deviation is preferentially set to 0, the correction control unit 24 provides a weighting constant K. The position deviation is calculated, and control is performed so that the total position deviation becomes zero.
Total position deviation = Self position deviation + K · Relative position deviation (K: Weight constant)
[0029]
As a result, even if there is a load difference between the drive shafts, the other drive shafts (DS2 axis to DS4 axis) can follow the reference axis (DS1 axis), and an excessive force is applied to the ram 1. In addition, the ram 1 can be positioned with high accuracy with stable control.
[0030]
In the position control unit (see FIG. 3) of the servo control apparatus of the present embodiment, the correction signal (relative position deviation signal) from the correction control unit is added to the input signal of the gain control unit 28. May be added to the output signal of the gain controller 28.
[0031]
In the present embodiment, the electric vender in which the ram 1 has four drive shafts has been described. However, it goes without saying that the present invention can be applied to a drive shaft having three axes or more than five axes. Yes.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of an electric vendor according to an embodiment of the present invention.
FIG. 2 is a system configuration diagram of a servo control device according to the present embodiment.
FIG. 3 is a detailed view of a position control unit (DS2 axis to DS4 axis) of the servo control device.
[Explanation of symbols]
1 Ram 2 Fixed Table 7 Ram Drive Device 8 AC Servo Motor 10 Ball Screw 11 Linear Encoder (Position Detector)
12 Detector 13 Correction Bracket 14 Motor Encoder 15 Reference Axis Control System 16 DS2 Axis Control System 17 DS3 Axis Control System 18 DS4 Axis Control System 19 NC Device 20 Position Controller 21 Speed Controller 22 Current Controller 23 Power Control unit 24 Correction control unit 25 Inter-axis position setter 26 Speed pattern generation unit 27 Target position calculation unit 28 Gain calculation unit

Claims (2)

A control method of an electric vendor that performs bending of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table,
Each servo motor that drives each drive shaft outputs a speed command signal in the position control unit by a position command signal from the outside and a position feedback signal from a position detector provided corresponding to each drive shaft position. The speed control unit is controlled by generating a current command signal based on the speed command signal, and the power control unit is controlled by generating an actual current for driving the servo motor based on the current command signal.
Servo motors related to other drive shafts other than a predetermined reference drive shaft among the drive shafts, the position control unit related to the other drive shaft, the other drive shaft generated in the correction control unit and the reference drive When a control signal based on a relative position deviation with respect to the shaft is input, control is performed in consideration of the relative position deviation, and the relative position between the other drive shaft and the reference drive shaft is included in the position control unit. A control method for an electric vendor, wherein a relative position deviation signal is input from an inter-axis position setter that sets the position to a desired value . A control device for an electric vendor that performs bending processing of a plate material by an upper die attached to a ram having three or more drive shafts driven by an electric motor and a lower die attached to a fixed table,
Each servo motor controller that drives each drive shaft receives a position command signal from the outside and a position feedback signal from a position detector provided corresponding to each drive shaft position, and outputs a speed command signal. A position control unit, a speed control unit that generates a current command signal based on the speed command signal from the position control unit, and a power control that generates an actual current for driving the servo motor based on the current command signal from the speed control unit With
Among the control devices, a control device related to another drive shaft excluding a predetermined reference drive shaft generates a control signal based on a relative position deviation between the other drive shaft and the reference drive shaft, A correction control unit that outputs to a shaft position control unit, and an inter-axis position setting unit that sets a relative position between the other drive shaft and the reference drive shaft to a desired value. A control device for an electric vendor.

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