JP7474189B2 - SERVO PRESS MACHINE AND METHOD FOR CONTROLLING SERVO PRESS MACHINE - Google Patents

Description

The present invention relates to a servo press machine and a method for controlling a servo press machine.

A servo press machine can freely change the speed of the slide and stop and reverse the rotation. There are various methods for generating the pendulum motion (the pendulum turning position, the acceleration during deceleration until the turning position is reached, the deceleration start position, the acceleration during acceleration after stopping at the turning position, and the acceleration end position) of the pendulum operation, which particularly increases output. The reason for performing pendulum operation is to increase the number of production units per hour, and if the crank angular velocity is the same, a greater increase in production number is expected by reducing the pendulum stroke. However, the pendulum stroke cannot be made as small as one desires, and since the feed device needs to feed the material (workpiece) to the next process during the pendulum motion, the pendulum turning position (highest position) needs to be higher than the feed start position (feedable position). Patent Document 1 discloses a press system that transports the workpiece while the slide moves between the feedable height and the standby height (highest position).

JP 2019-55426 A

In the above press system, the slide decelerates at a constant acceleration when it passes the feedable height, and the slide that stops at the standby height position accelerates at a constant acceleration after a predetermined time and begins to descend. In other words, in the above press system, the acceleration when the slide decelerates until it reaches the highest position, and the acceleration when the slide accelerates after it reaches the highest position are unnecessarily large, resulting in unnecessary standby time at the highest position. Furthermore, the unnecessarily large acceleration of the slide results in unnecessary energy consumption.

The present invention was made in consideration of the above problems, and its purpose is to provide a servo press machine and a control method for a servo press machine that are capable of optimizing the slide motion in a servo press that processes the workpiece fed by a feed device.

a control unit that controls the ascending and descending motion of the slide based on a predetermined slide motion; a command output unit that outputs a feed command to a feed device that feeds the workpiece to a next process when the ascending slide reaches a predetermined feedable position; and a signal detection unit that detects a signal from a detector that detects completion of the feed operation of the workpiece by the feed device, wherein the control unit controls the slide to start decelerating at a predetermined first acceleration when the ascending slide reaches the feedable position, and starts accelerating the slide at the first acceleration after the slide reaches a predetermined highest position, and continues accelerating the slide until the speed of the slide reaches a predetermined speed if a signal from the detector is detected before the descending slide reaches a predetermined detection check position, and controls the slide to stop at the feedable position if a signal from the detector is detected before the descending slide reaches a predetermined detection check position.

The control method for a servo press machine according to the present invention is a control method for a servo press machine that performs press processing on a workpiece by converting the rotation of a servo motor into a reciprocating linear motion of a slide using an eccentric mechanism that converts rotational motion into linear motion, and includes a control step of controlling the ascending and descending motion of the slide based on a predetermined slide motion, a command output step of outputting a feed command to a feed device that sends the workpiece to the next process when the ascending slide reaches a predetermined feedable position, and a signal detection step of detecting a signal from a detector that detects the completion of the feed operation of the workpiece by the feed device, and in the control step, when the ascending slide reaches the feedable position, This method of controlling a servo press machine is characterized in that when the slide reaches a predetermined highest position, the slide starts to decelerate at a predetermined first acceleration, and after the slide reaches a predetermined highest position, the slide starts to accelerate at the first acceleration to lower the slide, and if a signal from the detector is detected before the descending slide reaches a predetermined detection check position, the slide continues to accelerate until the speed of the slide reaches a predetermined speed, and if a signal from the detector is not detected before the descending slide reaches the detection check position, the slide is decelerated at a predetermined second acceleration to stop the slide at the feedable position.

According to the present invention, when the slide reaches the feedable position, deceleration of the slide begins at a first acceleration, and when the slide reaches the highest position, acceleration of the slide begins at the first acceleration without pausing the slide, and the slide is lowered, thereby realizing a slide motion in which acceleration during acceleration and deceleration of the slide is kept to a minimum. Also, if the completion of the feed operation of the workpiece material cannot be detected before the slide reaches the detection check position, the slide is decelerated at a second acceleration and stopped at the feedable position, thereby preventing damage to mold parts when the feed operation of the workpiece material is not performed normally.

FIG. 1 is a diagram showing an example of a configuration of a servo press machine according to an embodiment of the present invention. 6 is a diagram for explaining detection of completion of the feeding operation of the workpiece by the detection unit. FIG. 1A to 1C are diagrams showing an example of a slide motion (pendulum motion) in the present embodiment. 5A to 5C are diagrams for explaining a design method for a pendulum motion in the present embodiment. 5A to 5C are diagrams for explaining a design method for a pendulum motion in the present embodiment. 5A to 5C are diagrams for explaining a design method for a pendulum motion in the present embodiment.

The following describes in detail the embodiments of the present invention with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a servo press machine according to this embodiment. The servo press machine 1 converts the rotation of a servo motor 10 into a vertical reciprocating motion (reciprocating linear motion, lifting motion) of a slide 17 by an eccentric mechanism that converts rotational motion into linear motion, and performs press processing on a workpiece C (e.g., a sheet-like material) by utilizing the vertical reciprocating motion of the slide 17. The workpiece C is supplied by a feed device 200 (a device that feeds the workpiece C to the next process), which is an external device, and the completion of the feed operation of the workpiece C is detected by a detector 201 (misfeed detector), which is an external device. The servo press machine 1 includes a servo motor 10, an encoder 11, a drive shaft 12, a drive gear 13, a main gear 14, a crankshaft 15, a connecting rod 16, a slide 17, a bolster 18, a control device 100, and a control device 100.
has.

A drive shaft 12 is connected to the rotating shaft of the servo motor 10, and a drive gear 13 is connected to the drive shaft 12. A main gear 14 is engaged with the drive gear 13, and a crankshaft 15 is connected to the main gear 14, and a connecting rod 16 is connected to the crankshaft 15. The crankshaft 15 and the connecting rod 16 form an eccentric mechanism. This eccentric mechanism allows a slide 17 connected to the connecting rod 16 to move up and down relative to a stationary bolster 18. In this embodiment, the slide 17 is controlled to perform a pendulum motion (a reciprocating motion up and down that does not return to the top dead center). An upper die 19 is attached to the slide 17, and a lower die 20 is attached to the bolster 18.

The control device 100 includes a control unit 101, a command output unit 102, and a signal detection unit 103. The control unit 101 controls the ascending and descending movement of the slide 17 based on a predetermined slide motion (pendulum motion) stored in the memory unit. More specifically, the control unit 101 calculates a motor rotational position command value from commands for the position and speed of the slide 17 defined by the slide motion, and controls the rotational position, rotational speed, and current of the servo motor 10 based on the rotational position command. The rotational position of the servo motor 10 is detected by an encoder 11 attached to the servo motor 10.

When the ascending slide 17 reaches a predetermined feedable position, the command output unit 102 outputs a feed command to the feed device 200. Upon receiving this feed command, the feed device 200 starts the feed operation of the workpiece C, and feeds the workpiece C by a predetermined feed amount within a predetermined time.

The signal detection unit 103 detects a signal (ON signal) from the detector 201 that detects the completion of the feed operation of the workpiece material C. If the control unit 101 does not detect a signal (ON signal) from the detector 201 before the descending slide 17 reaches a predetermined detection check position, the control unit 101 decelerates the slide 17 and stops it at the feedable position. The feedable position is a position at which the feed operation of the workpiece material C becomes possible (a height at which the die and the workpiece material C do not interfere with each other), and the detection check position is a position higher than the feedable position and lower than the maximum position of the slide motion. In other words, the detection check position is a position that the slide 17 reaches after the feed time Tf (described later) of the feed device 200 has elapsed, and is also a position at which the slide 17 can be stopped at the feedable position by decelerating the descending slide 17 from that position at the maximum acceleration (second acceleration).

2 is a diagram for explaining the detection of the completion of the feed operation of the workpiece C by the detector 201. As shown on the left side of FIG. 2, during the descent of the slide 17 after the feed operation is completed, the touch sensor 202 provided on the detector 201 is in contact with the end of the workpiece C. Then, as shown in the center of FIG. 2, when the press processing is performed, the workpiece C and the touch sensor 202 are in a non-contact state. Then, as shown on the right side of FIG. 2, the end of the workpiece C and the touch sensor 202 approach each other due to the feed operation. When the workpiece C is fed to a specified position (the feed operation is completed), the end of the workpiece C and the touch sensor 202 come into contact with each other again, and an ON signal is output from the detector 201, and it is determined that the feed operation has been performed normally.

Figure 3 is a diagram showing an example of slide motion (pendulum motion) in this embodiment. The upper graph in the figure shows the change over time in slide position, and the lower graph in the figure shows the change over time in crank angular velocity. In addition, the solid line in the figure shows the position and angular velocity during normal operation (when the feed operation of the workpiece C is performed normally), and the dashed line in the figure shows the position and angular velocity when a misfeed is detected (when the feed operation of the workpiece C is not performed normally).

The slide motion in this embodiment is a pendulum motion, and the distance from the bottom dead center to the pendulum turning point (the highest position of the pendulum motion) is the pendulum stroke PS. When the ascending slide 17 reaches the feedable position, the feed operation of the workpiece C by the feed device 200 is started, and during normal operation, an ON signal (completion of the feed operation) is detected from the detector 201 before the descending slide 17 passes the highest position and reaches the detection check position. The time it takes from the start of the feed operation to the detection of the completion of the feed operation (the time from when the slide 17 passes the feedable position to when it passes the detection check position) is defined as the feed time Tf.

When the ascending slide 17 reaches the feedable position at a predetermined speed (for example, the maximum press speed), it starts to decelerate at a predetermined first acceleration, and when the slide 17 reaches the maximum position, it starts to accelerate at the same first acceleration and descends. Then, if an ON signal from the detector 201 is detected before the descending slide 17 reaches the detection check position (if the feed operation is performed normally), the acceleration of the slide 17 continues until it reaches a predetermined speed. On the other hand, if an ON signal from the detector 201 is not detected before the descending slide 17 reaches the detection check position (if a misfeed is detected), the slide 17 decelerates at a predetermined second acceleration and stops at the feedable position. In this way, by suddenly stopping the slide 17 at the feedable position when a misfeed is detected, damage to die parts such as pilot pins can be prevented.

The design method for the pendulum motion in this embodiment will be described using Figures 4 to 6. Here, the motion of the ascending slide 17 from when it reaches the feedable position, through the highest position, and when it reaches the feedable position again will be described. The horizontal axis of the graph in the figure indicates time, and the vertical axis indicates the crank rotation speed (unit: rpm). Note that the speed (rpm) is expressed as an absolute value without taking into account the rotation direction of the crank. The solid line in the figure indicates the change in speed over time during normal operation, and the dashed line in the figure indicates the change in speed over time when a misfeed is detected.

Also, the maximum press speed is Vd, and the time when the slide 17 passes the feedable position is 0. In FIG. 4, the speed when the slide 17 passes the feedable position and the speed when the feed time Tf has elapsed from that point are both Vd. The acceleration (second acceleration) during the sudden stop of the slide 17 is predetermined, and the time from when a misfeed is detected at the speed Vd to when the slide 17 stops due to the sudden stop is Ts. Here, the absolute value of the second acceleration is equal to or greater than the absolute value of the first acceleration. Note that this second acceleration is determined in relation to the maximum torque that the servo motor 10 can output, the moment of inertia of the driven part on the axis of the servo motor 10, and the number of continuous strokes (spm). The area of the triangle TL on the left side of the figure represents the amount of rotation of the crank (corresponding to the movement distance of the slide 17) from when the slide 17 passes the feedable position to when it reaches the highest position, and the area of the triangle TR on the right side of the figure represents the amount of rotation of the crank from when the slide 17 passes the highest position to when a misfeed is detected and it stops due to the sudden stop. In FIG. 4, in order to make the acceleration (crank angular velocity) during deceleration after the slide 17 passes the feedable position equal to the acceleration during acceleration after passing the highest position (to make the acceleration and deceleration as gradual as possible), the slide 17 is set to reach the highest position (speed becomes 0) in half the feed time Tf (Tf/2). However, in this case, the area of triangle TR is larger than the area of triangle TL, and slide 17 reaches the feed start position at time Tf, so the stop position of slide 17 due to the sudden stop when a misfeed is detected (slide position at time Tf+Ts) is lower than the feedable position.

5, a speed Va (Va<Vd) at time Tf is calculated so that the area of triangle TR is equal to the area of triangle TL. At this time, since the acceleration (Vd/Ts) during the sudden stop does not change, the time from when a misfeed is detected at speed Va until the slide 17 stops suddenly is the time T satisfying Va/Ts'=Vd/Ts.
s'. In other words, a speed Va that satisfies Vd×Tf/2=Va×(Tf+Ts'-Tf/2) is calculated. However, in this case, by changing the speed at time Tf, the acceleration during deceleration (Vd/(Tf/2)) and the acceleration during acceleration (Va/(Tf/2)) are no longer the same.

Therefore, as shown in FIG. 6, the velocity Va and time Ts' at time Tf, and the time Tf' at which the slide 17 reaches the highest position, are calculated so that the area of triangle TR is equal to the area of triangle TL and the acceleration during deceleration is the same as the acceleration during acceleration. In other words, the velocity Va and time Tf' are calculated so that the area condition Vd×Tf'=Va×(Tf+Ts'-Tf') is satisfied and the acceleration condition Vd/Tf'=Va/(Tf-Tf') is satisfied. In this embodiment, the absolute value of velocity Va is smaller than the absolute value of velocity Vd.

By using the above design method, when the ascending slide 17 reaches the feedable position at a speed Vd, it starts to decelerate at a first acceleration (Vd/Tf'), and when the slide 17 reaches the highest position, it starts to accelerate at a first acceleration (Va/(Tf-Tf')) and descends. If a misfeed is detected at time Tf when the slide 17 reaches the detection check position, the slide 17 decelerates at a second acceleration (Va/Ts') and stops at the feedable position. Under normal circumstances, when no misfeed is detected at time Tf (the ON signal from the detector 201 is detected), a pendulum motion is realized in which acceleration at the first acceleration continues until the speed Vd is reached.

According to this embodiment, the completion of the feed operation of the workpiece C can be checked at an optimal speed without having to stop the slide 17 while the pendulum swings back and forth during pendulum operation, which is expected to improve production efficiency. In addition, it is possible to minimize acceleration and the pendulum stroke PS while taking into account the feed time Tf and sudden stops due to misfeed detection. In other words, by slowing down acceleration and deceleration and eliminating unnecessary wait stops and operations, energy savings can be expected and the capacity of the energy supply device for driving the servo motor 10 can be reduced.

Although the embodiments of the present invention have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel aspects and effects of the present invention.

1...Servo press machine, 10...Servo motor, 11...Encoder, 12...Drive shaft, 13...Drive gear, 14...Main gear, 15...Crankshaft, 16...Connecting rod, 17...Slide, 18...Bolster, 19...Upper die, 20...Lower die, 100...Control device, 101...Control unit, 102...Command output unit, 103...Signal detection unit, 200...Feed device, 201...Detector, 202...Touch sensor

Claims (5)

A servo press machine that performs press processing on a workpiece by converting rotation of a servo motor into reciprocating linear motion of a slide using an eccentric mechanism that converts rotational motion into linear motion,
A control unit that controls the up-down movement of the slide based on a predetermined slide motion;
a command output unit that outputs a command to a feed device that feeds the workpiece to a next process when the slide reaches a predetermined feedable position during the upward movement of the workpiece;
a signal detection unit that detects a signal from a detector that detects completion of the feeding operation of the workpiece by the feeding device;
The control unit is
when the slide is ascending and reaches the feedable position, the control starts decelerating the slide at a predetermined first acceleration, and when the slide reaches a predetermined highest position, the control starts accelerating the slide at the first acceleration to descend the slide, and if a signal from the detector is detected before the descending slide reaches a predetermined detection check position, the control continues accelerating the slide until the speed of the slide reaches a predetermined speed, and if a signal from the detector is not detected before the descending slide reaches the detection check position, the control starts decelerating the slide at a predetermined second acceleration to stop the slide at the feedable position,
A servo press machine, characterized in that an absolute value of the second acceleration is greater than an absolute value of the first acceleration . In claim 1 ,
A servo press machine, characterized in that the absolute value of the speed at which the slide passes through the detection check position during a downward movement is smaller than the absolute value of the speed at which the slide passes through the feedable position during a upward movement. In claim 1 or 2 ,
A servo press machine characterized in that the detection check position is a position where the slide can be stopped at the feedable position when the slide is decelerated at the second acceleration during descent. In any one of claims 1 to 3 ,
A servo press machine, wherein the slide motion is a pendulum motion. A method for controlling a servo press machine that performs press working on a workpiece by converting rotation of a servo motor into reciprocating linear motion of a slide using an eccentric mechanism that converts rotational motion into linear motion, comprising the steps of:
a control step of controlling the up-down movement of the slide based on a predetermined slide motion;
a command output step of outputting a feed command to a feed device that feeds the workpiece to a next process when the slide reaches a predetermined feedable position during the upward movement of the workpiece;
and detecting a signal from a detector that detects completion of the feeding operation of the workpiece by the feeding device,
In the control step,
when the slide is ascending and reaches the feedable position, the control starts decelerating the slide at a predetermined first acceleration, and when the slide reaches a predetermined highest position, the control starts accelerating the slide at the first acceleration to descend the slide, and if a signal from the detector is detected before the descending slide reaches a predetermined detection check position, the control continues accelerating the slide until the speed of the slide reaches a predetermined speed, and if a signal from the detector is not detected before the descending slide reaches the detection check position, the control starts decelerating the slide at a predetermined second acceleration to stop the slide at the feedable position,
2. A method for controlling a servo press machine, wherein an absolute value of the second acceleration is greater than an absolute value of the first acceleration .

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