JP2833504B2 - Position control method of forging press transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the function of a transfer device for a forging press.

[0002]

2. Description of the Related Art Forging presses are different from the conventional single molding process in that a plurality of dies are arranged in a die holder in order to dramatically improve productivity by mass production, and a plurality of moldings are simultaneously performed. The transfer method is mainly used, and a transfer device for sequentially supplying a molding material into a plurality of dies has been developed and put into practical use. The basic condition of the transfer device is to take out the material in the mold at the required timing and carry it into the next mold.Therefore, beam driving devices are provided on both sides of the forging press, and these two devices The two beams erected horizontally between the dies are combined in three directions of up-and-down movement (lift movement), forward and backward movement (feed movement), and opening and closing movement (clamp movement) to combine the two beams. It has the function of grasping the material (work) between the fingers attached in the direction, moving it to the required position, and releasing it.

[0003] The beam drive of the transfer device must repeat the operation of the fingers in three directions in order and synchronize with the operation of the ram of the forging press. All the contents also fluctuate, and the control of the position that can follow the fluctuations is required more and more precisely. As a control method of a transfer device according to the latest related art, a method of operating under the control of a CPU using a servomotor is adopted.

FIG. 2 is a perspective view of a transfer device cited from Japanese Patent Application Laid-Open No. 5-92228 previously proposed by the applicant of the present invention. In FIG. 2, an inner frame 6B is slidably inserted vertically into an outer frame 6A fixed to a main body of a forging press (not shown). The frame 6B is driven by a lift servomotor 5A via a ball screw. Up and down. The clamp frame 7 is provided with the inner frame 6B
, The beam 2 suspended at the bottom end advances and retreats left and right by the driving of the clamping servomotor 5C, which is mounted on itself, while the feed servomotor 5B is driven by the feed servomotor 5B. That is, by driving three types of servomotors, the beam 2 is connected via the ball screws connected to each other.
Is configured to repeat three-dimensional operation.

FIG. 3 is a control circuit diagram of a transfer device taken as an example. The input device 1 has a slot 11 of a floppy desk in which an operation pattern to be programmed by a forging press is programmed, and an initial condition of each operation pattern is input. This input goes to CPU3 and RAM
Are also stored in the respective areas, and are processed and displayed on the display device CRT 21 as operation curves indicating the locus of the position of the member. The servo motor 5 that drives each operation is a CP
A pulse signal generated from the pulse generator 4 receiving the output signal of U3 is output to a servo control device (servo amplifier) 41 via a drive circuit, and rotates as instructed.

The actual number of revolutions of the servo motor 5 is determined by a pulse detector (PG) 42 using a pulse generating encoder.
Is sent back as a feedback pulse and input to the servo controller 41. Here, the input pulse and the feedback pulse are compared to calculate a deviation amount, and an operation command is output again as a pulse signal. In the case of two servo motors 5A and 5C which require the same control like a clamp device, a signal comparator is interposed between the two servo controllers to detect a signal mismatch, and to detect the mismatch. In case CPU
An error is fed back to the sequencer 31 via a command and a warning is issued.

FIG. 4 shows that the rotation angle of the crankshaft where the ram of the forging press is located at the top dead center is 0 degree, the rotation angle of the crankshaft located at the bottom dead center is 180 degrees, and transfer corresponding to the movement during this period. The movement of the three-dimensional position of the beam of the apparatus is indicated by an angle, and is called an operation angle-stroke diagram. This figure shows that the CP is inserted by inserting a floppy disk with programming into the input device.
The image processing is performed by U and displayed on the CRT. The stroke curve P, the feed curve F, the lift curve L, and the clamp curve C of the forging press (ram) are displayed so that the mutual positional relationship can be recognized. It has become.

[0008]

As shown in the drawing, the operation of the beam of the transfer device is controlled by a pulse generator and a pulse control device connected to a CPU.
A number of operation patterns are set in the forging press, and the rationalization of selecting the operation pattern that provides the most efficient productivity for each product is realized. That is, even if the clamp curve C shown in FIG. 4 is closest to the stroke curve P of the forging press, no interference (collision) should occur unless it intersects. Therefore, by setting the program as close as possible, If other conditions permit, even if the forging press cycle is further shortened and high-speed operation is required, the transfer device follows the speed and draws behavior that does not cause interference. It's easy to think of it, but you're facing a big problem here.

[0009] Further increasing the operating speed of the forging press and shortening the cycle should directly lead to an improvement in productivity, but in practice there is a limit to the plastic deformation of the metal material added to form the material. If the molding speed is higher than the limit of the moldability of the material, cracking of the product will occur. In addition, there is a certain mechanical limit to the speed of the operation of grasping, moving, and releasing the material. As another means for increasing the productivity, it is conceivable to set the time difference between the operation of the forging press and the operation of the transfer device to a minimum as long as no interference occurs, that is, to minimize the loss time. However, since servomotors generally have a phenomenon called accumulation pulses, there is a slight time delay corresponding to this phenomenon, and it is inevitable that a slight difference appears between the command value and the operation value, and the servomotor performance is reduced. This difference is amplified as the limit is approached.

In FIG. 4, a clamp curve C drawn by a solid line
Indicates a locus based on a set value, which indicates a locus based on a clamp command value calculated and displayed in the input operation pattern, but is actually represented by a dotted line due to a time delay caused by the presence of accumulated pulses. Appears as a locus of motion values to be drawn. Since the horizontal axis represents the passage of time replaced by the rotation angle of the crankshaft of the forging press, the angle at which the position of the clamp and the position of the ram approach the shortest (in the example of the figure, about 110 ° or about 110 °). Even though the distance at about 250 °) is indicated as S, the distance at about 110 ° is actually only s, and depending on this distance, the finger tip that should be able to evade smoothly is In reality, the danger of colliding with the ram tip (mold) is probably hidden.

Such a time delay t is not uniformly determined because individual conditions such as the operating speed and the operating distance of the servomotor are different from each other, and varies depending on the characteristics of individual forging presses. It is extremely difficult to eliminate the collision by controlling only the calculation, and after all, there is no other way than to give up the productivity improvement, overestimate the delay time t, and prevent the interference with a considerable margin. Easy to settle down.

In order to reduce the time delay t, there is a method of setting the servo motor capacity excessively. However, if the capacity of the servo motor is increased, the economic burden is greatly increased. The size and weight are reduced by selecting a model that slightly exceeds the ability to do so. Further, in the servo motor, the difference between the command value and the operation value can be reduced and the time delay t can be reduced by increasing the servo gain. For example, FIG. 5 is a conceptual diagram showing a temporal relationship from when an operation command is output from a servo amplifier to a servomotor until it appears as an actual operation, in which members are started in accordance with an input program signal. A state in which the speed is gradually increased to reach a predetermined speed, and further gradually decelerated, stopped at a predetermined pulse position, and subsequently started after a certain time has elapsed, is illustrated by a relationship between a moving distance and time. It is. The solid line (A) in the figure is the locus of the command value input from the servo amplifier, and the dotted line (B) is the locus of the operation value when the servo gain is appropriate. Delay occurs. When the servo gain is increased to the maximum to eliminate the time delay t, the zigzag line (C)
The time delay t almost overlaps with the solid line (A) and is almost eliminated as shown in FIG. 4. However, such a condition is nothing less than an excessive response of the servomotor, and is accompanied by minute rotational vibrations and a serious obstacle to control. In addition, it may cause a failure of the device.

Japanese Unexamined Patent Publication No. 4-33731 proposes a work feeder control method for increasing a servo gain when a synchronization delay occurs. However, this prior art discloses a work feeder speed command value or a supply current value. If any of them exceeds the maximum allowable value, the control signal is corrected to improve the position loop gain of the servo system causing the deviation so as to increase. However, the object of this prior art is limited to a solution for a time delay that occurs in an unsteady state.
Since always increasing the servo gain to the maximum in steady operation creates another problem as described above, such a problem does not solve the problem of the time delay in the steady state, and the problem that the loss time cannot be reduced remains. Remains intact.

Japanese Patent Application Laid-Open No. 2-108499 discloses a servo amplifier which detects a working angle of a forging press, calculates a target movement speed of a feeder corresponding to the detected angle, and drives a servo motor so as to match the target movement speed. When issuing a command from the (servo control device), the gist is to calculate the target movement speed of the feeder in consideration of the delay time of the servo amplifier. In this prior art, as shown in FIG. 6A, the problem that the final bundle angle x of the feeder based on the working angle of the forging press becomes large is taken up as a problem.
In order to solve the problem, a curve of the target movement speed of the feeder is commanded in advance by taking the delay time into consideration, so that the position of the final bundle angle that is finally located coincides with the predetermined position as shown in FIG. Is set to However, even if the operation position that finally ends coincides with the set position, the progress in the middle does not coincide, so in order to enhance productivity, the positional relationship of the operation of the feeder corresponding to the operation trajectory of the ram, There is concern that the reduction to the last minute is a rather unstable factor, and the problem remains as before.

In order to solve the above-mentioned problems, the present invention directly controls the path during the operation of the transfer device, in particular, the positional relationship at the time of the closest approach to the ram, reduces the loss time to the limit of interference, and reduces the loss time of the forging press. It is an object of the present invention to provide a method of controlling a transfer device that improves productivity to the utmost.

[0016]

A position control method for a transfer device of a forging press according to the present invention comprises an input device 1 for writing initial conditions and a beam 2 for reading the initial conditions.
Which calculates the amount of displacement and outputs the corresponding pulse generation signal
A control method of a forging press transfer device including a PU 3 and a pulse generator 4 and synchronizing each servo motor 5 for driving a three-dimensional operation of the beam 2 with an operation of a forging press, wherein the transfer device is operated in advance. Check the deviation between the commanded position in three directions of vertical movement, forward / backward movement, opening / closing movement and actual operation position, and clamp by opening / closing movement.
Where the curve and the forging press stroke curve are closest
Operation pattern number chromatic delay time t is stored in the CPU 3, it is slow-corresponding to the initial condition input during actual operation in addition to operation of advance correction time t at the limit of the interference or
The above problem was solved by performing position control with reduced loss time.

[0017]

Since the time delay of each operation curve of the transfer device corresponding to the operation curve unique to the forging press is stored in the CPU 3 in advance , among the operation patterns input to the input device, particularly the clamp curve and the forging are used. Press Straw
An arithmetic operation is performed to advance and correct the unique time delay at the position where the work curve is closest to the target curve to cancel the time delay, and to guide the rotation of the servo motor so as to match the position of the set value with the position of the operation value. As a result, even if the beam operation of the transfer device corresponding to the operation of the forging press is set to the minimum loss time as long as interference does not occur, the desired motion is always maintained while maintaining the safe positional relationship. Is repeated , so that accident avoidance and safety
It also has the effect of maximizing productivity .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to an operating angle-stroke diagram of FIG. In FIG. 1, it is the clamp operation that the beam (finger) of the transfer device most easily interferes with the raising / lowering operation of the ram. When the P-curve (trajectory of the ram operation) draws a nearly sinusoidal curve from the top dead center (crankshaft angle 0 °) and descends to the bottom dead center (crankshaft angle 180 °) to perform the molding operation,
The curve C (the trajectory of the clamp operation) starts releasing the grip of the work from around 90 ° and releases the work at around 140 ° to stand by. The work starts to be gripped around 220 ° when the forming operation is completed, and is completely gripped at 270 °.
The point where the P curve and the C curve come closest to each other is at the moment when the clamp tip tries to release the work (about 110 crankshaft angles).
°) and the moment of trying to grip the work (crankshaft angle is about 250 °). First, a displacement meter is attached to the beam in advance, the transfer device is driven, and the feed,
The delay time t is detected in advance by measuring the command position and the operation position in the three directions of the lift and the clamp.

At about 110 ° of the crankshaft angle shown in FIG. 1, the ram curve and the clamp curve of the forging press become the closest. In other words, the ram tip (die) and the finger come closest to each other. A minimum value S is set as the interval between the ram curve and the clamp curve so that the finger does not collide with the ram tip (die).
A curve passing through a position distant only by a distance is a set value of the clamp curve and may be an operation value. In the case of the conventional example, since a delay time t occurs between the command value (set value) and the operation value, the ram curve and the clamp curve of the forging press may interfere with each other. Is performed to advance the delay time t, and the command value subjected to the advance correction is output to the servomotor. Therefore, the set value and the operation value become almost the same, and the necessary minimum distance S is secured. As a matter of course, a command value whose positional relationship has been adjusted so as not to cause interference at the closest point between the ram curve and the clamp curve of the other forging press (approximately 250 ° in crankshaft angle) is issued.
Further, when the advance angle is corrected only for the crank, the timing between the feed and the lift is different, so it goes without saying that the feed curve and the lift curve are also advanced so that the timing does not deviate from the crank curve.

[0020]

As described above, in the present invention, the delay time t is detected by measuring the command position and the operation position in three directions of feed, lift and clamp in advance, and the time delay is determined by the CPU. And the lead angle correction is performed so that the set value and the operation value of the clamp curve become substantially the same, and the lead angle correction is performed so that the timing of the feed curve and the lift curve does not deviate from the timing of the clamp curve. In other words, the present invention performs not only the position control of the start point and the end point, but also the contour control focusing on the trajectory in the middle thereof, particularly, the positional relationship between the ram curve and the clamp curve that come closest. Therefore, it is not necessary to consider a considerable margin time so that the ram curve and the clamp curve of the forging press do not interfere with each other as in the related art, and the cycle of the process can be shortened.
In other words, interference between members can be reliably prevented,
The productivity can be further improved.

[Brief description of the drawings]

FIG. 1 is an operating angle-stroke diagram according to the present invention.

FIG. 2 is a perspective view of a transfer device used for carrying out the present invention.

FIG. 3 is a control circuit diagram of the device.

FIG. 4 is a conventional operation angle-stroke diagram.

FIG. 5 is a moving time-moving distance relationship diagram showing one of the problems of the prior art.

FIG. 6 is a movement speed-time relationship diagram showing an example of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input device 2 Beam 3 CPU 4 Pulse generator 5 Servo motor 6 Frame 7 Clamp frame 11 Floppy insertion port 12 Keyboard 21 CRT 31 Sequencer 41 Servo control unit 42 Pulse detector 43 Synchronous comparator P Operation curve of forging press (ram) F Operation curve of feed L Operation curve of lift C Operation curve of clamp

Claims (1)

(57) [Claims] 1. An input device 1 for writing an initial condition, a CPU 3 for reading the initial condition, calculating a displacement amount of a beam 2, and outputting a corresponding pulse generation signal, and a pulse generator 4.
In the control method of the forging press transfer device for synchronizing each servo motor 5 for driving the three-dimensional operation of the beam 2 with the operation of the forging press, the transfer device is operated in advance to raise, lower, move forward and backward, open and close. check the deviation between the actual operating position and the three-way command position of movement, stroke of the forging press and clamp curves with open and close movement
The CPU 3 stores the delay time t having the operation pattern at the position where the peak curve approaches the closest, and adds an operation for advancing the delay time t corresponding to the initial condition input during the actual operation to limit the interference. A position control method for a forging press transfer device, characterized in that position control is performed with a loss time reduced to a maximum.