JPH10113794A - Method for controlling break through buffer in press machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically search the most suitable buffer position efficiently with a few shot by raising a buffer piston by a 1st and a 2nd prescribed distance until the max. value of oil pressure in a buffer hydraulic cylinder is reached to more than the prescribed value in an initial time of starting the automatic searching. SOLUTION: In the time of automatically searching the most suitable buffer position in the break through time, at the initial time of starting to search, until the max. value of oil pressure in a buffer hydraulic cylinder 10 is made more than a prescribed value, a piston 12 of this buffer hydraulic cylinder 10 is raised roughly by every 1st prescribed distance. Therefore, this piston position is approached rapidly nearby the most suitable buffer position. Next, the position of the piston 12 is raised by every 2nd prescribed distance being smaller than the 1st prescribed distance, when the prescribed most suitable position deciding condition is filled with the break through evaluation signal inputted at each piston position during this time, the piston 12 is moved to the most suitable buffer position decided on this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a breakthrough buffering control method for a press machine which reduces a vibration and a breaking sound by damping a breakthrough generated when a blank is punched by a press machine.

[0002]

2. Description of the Related Art In a press machine, when a material is punched, a so-called breakthrough phenomenon occurs, which causes vibration and breaking noise. Conventionally, in order to improve the working environment of the press machine, the vibration and the breaking noise have been reduced.

Various buffer control devices have been conventionally proposed to buffer the breakthrough. For example, Japanese Patent Application Laid-Open No. 7-251300 discloses the following buffer control device. That is, a guide post is provided on the upper die of the press machine, a buffer hydraulic cylinder is provided on the lower die so as to face the guide post, and the buffer hydraulic cylinder has a built-in buffer piston that can move vertically. I have. Further, the press machine is provided with an air-oil tank filled with oil and air in two chambers separated by a built-in piston portion, respectively. The oil chamber of the air-oil tank, the buffer hydraulic cylinder, Are connected by a pipe filled with oil. And when the press machine operates,
When the guide post is pressed against the buffer piston, the air in the air-oil tank is compressed through the buffer hydraulic cylinder, the piping, and the oil in the air-oil tank to buffer the breakthrough.

[0004] At this time, the height of the cushioning piston is controlled to adjust the contact position with the guide post, so that the optimal buffering timing of breakthrough can be obtained. In order to adjust the height of the buffer piston, a timing adjusting device is provided which operates a piston portion of the air-oil tank using a stepping motor as an actuator to supply and discharge oil to and from the buffer hydraulic cylinder. Then, a breakthrough evaluation signal such as vibration or breaking sound of the press machine during breakthrough is separately detected by a sensor, and the control device determines an optimum timing based on the detected value and outputs a command to the timing adjustment device. ,
The vibration and the breaking sound are controlled to be minimized.

[0005]

However, in the conventional buffer control method, the buffer position at the optimal timing is automatically searched. However, the number of press shots (the number of punching) required to determine the optimal buffer position is small. More. For this reason, workers are suffering from large vibrations and breaking sounds during breakthrough during that time. Alternatively, in the case of multi-product small-quantity production, the production of the product may be terminated before the optimal buffer position is determined. Therefore,
When automatically exploring the optimal buffer position, it is an important issue how many shots the press machine can determine the optimal buffer position.By improving the conventional buffer control method, the number of shots is reduced, that is, There is a need for a buffer control method that can efficiently and automatically search in a shorter time.

[0006] Conventionally, once the optimal buffer position is determined and the buffer hydraulic cylinder is moved to this position, it is monitored whether the optimal buffer position does not change. If the breakthrough evaluation signal exceeds the monitoring threshold for some reason, the optimum buffer position is automatically searched again. However, at the time of this re-exploration, the vibration state and the sliding speed of each part of the press machine, that is, the number of shots per unit time (press production speed) and the like may have changed with respect to the start of operation (the above-mentioned unbuffered state). Therefore, it may take time to determine the optimal buffer position. For this reason, there is a demand for a buffer control method that enables automatic search in a short time even during the re-search.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a breakthrough buffer control method for a press machine capable of automatically exploring an optimum buffer position efficiently with a small number of shots. I have.

[0008]

Means for Solving the Problems, Functions and Effects In order to achieve the above-mentioned object, the invention according to claim 1 is directed to a buffer hydraulic cylinder 1 provided below a slide of a press machine.
The buffer piston 12 of 0 is moved to the search origin before the automatic search of the optimum buffer position is started, and a breakthrough evaluation signal is input at the search origin at the time of press punching without buffering.
The evaluation value of the breakthrough evaluation signal without buffering is stored as reference data, and the breakthrough occurrence time calculated based on the reference data is stored as the expected breakthrough occurrence time. The piston 12 is raised by a predetermined distance, and the evaluation value is calculated based on a breakthrough evaluation signal input near the expected breakthrough occurrence time at the time of press punching at each piston position, and the calculated evaluation value and the reference data are calculated. The maximum value of the evaluation value when the difference is the largest and the optimal buffer position of the buffer piston 12 at the minimum value are automatically searched, and the buffer piston 12 is moved to the optimal buffer position to buffer the breakthrough. In the breakthrough buffer control method of a press machine, at the beginning of the automatic exploration,
The buffer piston 12 is moved by a first predetermined distance until the maximum value of the hydraulic pressure of the buffer hydraulic cylinder 10 becomes a predetermined value or more.
Then, the buffer piston 12 is raised by a second predetermined distance smaller than the first predetermined distance, and during this time, when the automatic search is performed at each piston position and the optimum position determination condition is satisfied, The buffer piston 12 is moved to the optimal buffer position determined by the automatic search.

According to the first aspect of the present invention, when automatically searching for the optimum buffering position at the time of breakthrough, at the beginning of the search, the buffering is performed until the maximum value of the hydraulic pressure of the buffer hydraulic cylinder reaches a predetermined value or more. The piston of the hydraulic cylinder is raised roughly by a first predetermined distance. As a result, the piston position can be quickly brought closer to the vicinity of the optimal buffer position. Next, the position of the piston is raised by a second predetermined distance (however, smaller than the first predetermined distance). During this time, the breakthrough evaluation signal input at each piston position satisfies a predetermined optimum position determination condition. When
The piston is moved to the optimal buffer position determined by this. As a result, the automatic search can be completed with a small number of shots, and the piston can be set to the optimum buffer position in a short time.

[0010] The invention described in claim 2 is the same as the claim 1.
In the break-through buffer control method for a press machine described in the above, if the maximum value of the hydraulic pressure of the buffer hydraulic cylinder 10 is equal to or more than the predetermined value, the hydraulic pressure is then smaller than the first predetermined distance, and the second The third that is larger than the predetermined distance
The automatic exploration is performed by raising the buffer piston 12 by a predetermined distance, and after the evaluation value of the breakthrough evaluation signal at each piston position becomes equal to or less than a predetermined value A with respect to the reference data, In this method, the buffer piston 12 is moved up by two predetermined distances.

According to the second aspect of the present invention, the buffer piston of the buffer hydraulic cylinder is roughly moved by the first predetermined distance until the maximum value of the hydraulic pressure of the buffer hydraulic cylinder reaches a predetermined value or more at the beginning of the search. After that, until the evaluation value (for example, acceleration PP value) of the breakthrough evaluation signal becomes equal to or less than a predetermined value with respect to the reference data in the non-buffered state, the distance is smaller than the first predetermined distance, and The piston is raised by a third predetermined distance that is larger than the second predetermined distance. In this way, the position of the buffer piston for the search is subdivided, and the search is started at a coarse pitch at the start of the search, and at a fine pitch when approaching the optimum buffer position, so that the optimum buffer position is quickly determined. It becomes possible. Then, when the value is close to the optimal buffer position, instead of checking the magnitude of the hydraulic pressure, whether or not the evaluation value is the minimum is checked. Therefore, a position closer to the optimal buffer position can be more quickly searched.

Further, the invention described in claim 3 is the first invention.
Or the break-through buffer control method for a press machine according to item 2, wherein the optimum position determination condition is a predetermined number of times from the position of the buffer piston 12 at which the minimum value of the evaluation value occurs.
When the minimum value cannot be updated even if the distance is continuously increased by the second predetermined distance, or the difference between the reference data and the evaluation value at the current position is the difference between the reference data and the minimum value. , When at least one of the values is smaller than the predetermined value times, is satisfied.

According to the third aspect of the present invention, when at least one of the two optimum position determination conditions is satisfied during the automatic search, it is determined that the search for the optimum buffer position has been completed. That is, when the minimum value cannot be updated even if the minimum value of the evaluation value is increased by the second predetermined distance continuously from the position of the buffer piston 12 at which the minimum value has occurred a predetermined number of times M, or the reference data and When the difference between the evaluation value at the current position and the difference between the reference data and the minimum value is smaller than a predetermined value, and at least one of them is satisfied, the position of the cushioning piston 12 is further raised. It is determined that the evaluation value cannot be minimized even if it is performed. Thereby, the number of shots for determining the optimal buffer position can be reduced.

Further, according to the present invention, the buffer hydraulic cylinder 10 provided below the slide of the press machine is provided so that the evaluation value of the breakthrough evaluation signal at the time of press punching becomes the minimum value. In the breakthrough buffer control method for a press machine for automatically exploring and moving the optimum buffer position of the piston 12 to this position and monitoring the change of the evaluation value at this optimum buffer position, the evaluation value at the optimum buffer position is It monitors whether or not the minimum value is equal to or more than a predetermined monitoring threshold value. A temporary minimum value of the evaluation value at the piston position and the piston position corresponding to the minimum value are automatically re-probed, and thereafter, the upper end of the plurality of piston positions or When the temporary minimum value is shown at the lower end, the buffer piston 12 is further moved by a predetermined distance above the upper end showing the temporary minimum value, or below the lower end showing the temporary minimum value, and the evaluation is performed. In this method, the piston position indicating the minimum value of the value is automatically re-searched, and the piston position is set as a new optimal buffer position, and the buffer piston 12 is moved to the new optimal buffer position.

According to the present invention, at the time of monitoring at the optimum buffer position, if the evaluation value at the optimum buffer position has changed from the minimum value, at least two points above and below the current optimum buffer position. A temporary minimum value and a piston position corresponding to this minimum value are searched for at a plurality of piston positions at least five or more in total. Then, if there is a possibility that there is a position indicating a true minimum value (minimum value) above or below the lower end of the plurality of searched piston positions, the upper end indicating the temporary minimum value The position that shows the true minimum value is re-explored further upward or below the lower end. As a result, it is possible to search for a position near the current optimum buffer position and showing a minimum value (the optimum buffer position) in a shorter time.

According to a fifth aspect of the present invention, in the method for controlling a breakthrough of a press machine according to the fourth aspect,
At the time of monitoring at the optimal buffer position, when automatically re-exploring the minimum value and the piston position corresponding to the minimum value at a plurality of piston positions centered on the optimal buffer position, the minimum value is the optimal value. When the minimum value at the buffer position is equal to or more than a predetermined value, the automatic exploration is performed from the beginning after moving the buffer piston 12 to the search origin at the time of non-buffering before the automatic search starts, and the minimum value is When the minimum value is smaller than a predetermined value, the piston position corresponding to the minimum value is set as a new optimal buffer position, and the buffer piston 12 is moved to a new optimal buffer position.

According to the fifth aspect of the present invention, if the position deviates from this position during monitoring at the optimum buffer position (the evaluation value of the breakthrough evaluation signal changes by a predetermined value or more), the previous optimum buffer position is again applied. Automatic exploration is performed at a plurality of piston positions at least at five or more positions around the position. As a result, a position where the evaluation value becomes the minimum (in this position, the evaluation value is likely to be the minimum value) within the range near the current optimum buffer position can be searched with a small number of shots. Further, when the obtained minimum value is larger than a predetermined value with respect to the minimum value at the optimal buffer position, the operating state and operating conditions of the press machine have changed from the beginning of operation, so that the optimal buffer position of the Since the determination does not converge and it is determined that automatic search is difficult, the buffer piston is moved to the search origin to perform automatic search from the beginning. As a result, the time required for re-exploration can be shortened, and the entire automatic exploration time can be shortened.

According to a sixth aspect of the present invention, in the method for controlling breakthrough of a press machine according to the fourth aspect,
At the time of monitoring at the optimal buffer position, if the slide speed of the press machine exceeds a predetermined range, the breakthrough evaluation signal data input at this time is discarded, and a breakthrough evaluation signal is input after the slide speed is stabilized again. The monitoring threshold value is checked based on the breakthrough evaluation signal.

According to the sixth aspect of the present invention, if the slide speed of the press machine changes significantly for some reason during monitoring at the optimum buffer position, the reference data and the predicted breakthrough stored when the buffer is not buffered occur. Since the time is different from the current time, even if re-exploration is performed as it is,
The automatic search for the optimum buffer position does not converge, and there is a great possibility that it takes time to complete the search. Therefore, in such a case, the breakthrough evaluation signal data (eg, acceleration data) input at this time is discarded, and a new breakthrough evaluation signal is input after waiting until the slide speed is stabilized again. The monitoring threshold check is performed based on the evaluation value. As a result, the time required for the re-exploration is shortened, and the entire automatic exploration time is shortened.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a breakthrough buffer control method for a press machine according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a configuration diagram of a press machine provided with a shock absorber for executing breakthrough shock control according to the present invention. FIG. 1 (1) is a front view, and FIG. 1 (2) is a side view. ing. In the figure, an upper die 2 is fixedly mounted on a vertically moving slide 1, and a punch 3 and one guide post 4 are attached to the upper die 2. A lower die 6 is fixed to the bolster 5, and a die 7 is attached to the lower die 6 at a position facing the punch 3.

A buffer hydraulic cylinder 10 composed of a cylinder 11 and a buffer piston 12 is provided at a position facing the guide post 4 of the lower die 6. The shock-absorbing hydraulic cylinder 10 is mounted so that the shock-absorbing piston 12 moves up and down, and the shock-absorbing piston 12 is controlled so as to abut the guide post 4 when the slide 1 moves up and down. The buffer hydraulic cylinder 10 may be located below the slide 1 and at a position facing the guide post 4, and may be located above or inside the bolster 5, for example.

The cylinder chamber at the bottom of the cylinder 11 is filled with oil, and this cylinder chamber is connected to the empty oil tank 13 through a pipe 15. Also, the air-oil tank 13
Is connected to a hydraulic device 20, and the hydraulic device 20 is connected to a control device 40. Control device 40
Outputs a drive command to the hydraulic device 20 and controls the amount of oil in the cylinder chamber of the cylinder 11 via the air-oil tank 13. Thereby, the height of the buffer piston 12 is controlled, and the buffer timing at the time of breakthrough is adjusted.
The air-oil tank 13 is used as an example of a hydraulic accumulator, but is not limited thereto, and may be, for example, a spring-type accumulator whose hydraulic pressure is smoothed by a spring or the like.

A crankshaft angle sensor 16 for detecting the crankshaft rotation angle is attached to a crankshaft for moving the slide 1 up and down. Further, a hydraulic pressure sensor 17 for detecting the magnitude of the hydraulic pressure is provided in the cylinder chamber of the cylinder 11 of the buffer hydraulic cylinder 10, and a bolster acceleration sensor 18 for detecting the vibration acceleration at the time of breakthrough is provided for the bolster 5. I have. The respective detection signals from the crankshaft angle sensor 16, the oil pressure sensor 17, and the bolster acceleration sensor 18 are input to the control device 40. The control device 40 is configured by, for example, a computer system mainly including a microcomputer, performs predetermined processing and determination based on the input signal, controls the position of the buffer piston 12, and performs buffer control during breakthrough. Do. Further, the control device 40 has a built-in rotary cam function, and can turn on or off a predetermined signal within a predetermined crankshaft angle range set in advance. The rotary cam function may be realized by separately providing an electronic rotary cam device, a rotary cam contact, and the like.

FIG. 2 is a circuit diagram showing a configuration example of the hydraulic device 20. In the same figure, the ascending plunger pump 2
1a is composed of a hydraulic chamber 22a, an air chamber 23a, and a piston 24a. The head side and the bottom side of the air chamber 23a are connected to the factory air 26 via two positions of solenoid valves 25a for ascending. The hydraulic chamber 22a and the piston 24a form a plunger pump, and discharge a predetermined amount of oil when air pressure is applied to the bottom side of the air chamber 23a, and suck a predetermined amount of oil when air pressure is applied to the head side. Has become. The hydraulic chamber 22a is connected to an open-type reservoir tank 27 via a pipe 30. A first check valve 31 is interposed in the pipe 30. The first check valve 31 controls the reservoir. Oil flows from the tank 27 toward the hydraulic chamber 22a. The hydraulic chamber 22
a is connected to the oil chamber side of the air-oil tank 13 via a pipe 32, and a second check valve 33 is interposed in the pipe 32, and the second check valve 33 controls the hydraulic chamber 22a.
The oil flows in the direction of the empty oil tank 13 from above. The oil chamber of the air-oil tank 13 is connected to the buffer hydraulic cylinder 10 by a pipe 15. The air-oil tank 13 is provided with an air chamber 14, and the air chamber 14 is filled with air having a predetermined pressure to apply a predetermined pressure to the oil.

The lowering plunger pump 21b is connected to the hydraulic chamber 2
2b, an air chamber 23b, and a piston 24b. The head side and the bottom side of the air chamber 23b are located at two positions.
5b, it is connected to the factory air 26. Hydraulic chamber 2
The piston 2b and the piston 24b form a plunger pump, which discharges a predetermined amount of oil when air pressure is applied to the bottom side of the air chamber 23b, and sucks a predetermined amount of oil when air pressure is applied to the head side. I have. Hydraulic chamber 2
2b is connected to the reservoir tank 27 via a pipe 34, and a third check valve 35 is interposed in the pipe 34, and the third check valve 35 causes the hydraulic chamber 2
Oil flows from 2b to the reservoir tank 27. The hydraulic chamber 22b is connected to the oil chamber of the air-oil tank 13 by a pipe 36.
The fourth check valve 37 allows oil to flow from the oil chamber of the empty oil tank 13 in the direction of the hydraulic chamber 22b.

The solenoids of the ascending solenoid valve 25a and the descending solenoid valve 25b are connected to a controller 40. The control device 40 controls the crankshaft angle sensor 1
6. Each detection signal from the oil pressure sensor 17 and the bolster acceleration sensor 18 is input, and the movement distance of the position (height) of the buffer piston 12 is calculated based on the detection signals. Then, the amount of oil corresponding to the calculated moving distance is stored in the cylinder 1
1 or the solenoid valve 2 for lowering, respectively, so as to be fed to the cylinder 1 or discharged from the cylinder 11.
The direction of 5b is switched.

In FIG. 2, the ascending solenoid valve 25a is at the position (a), in which air pressure is applied to the head side of the air chamber 23a of the ascending plunger pump 21a by the factory air 26, and the piston 24a is moved to the right side. And the oil from the reservoir tank 27 into the hydraulic chamber 22a
Inhaled via 0. At this time, the lowering solenoid valve 25b is also at the position (a), and air is applied to the bottom side of the air chamber 23b of the lowering plunger pump 21b by the factory air 26, and the piston 24b moves to the left to move to the hydraulic chamber. The oil of 22 b is sent to the reservoir tank 27 via the pipe 34.

In order to raise the buffer piston 12, the operation of the lowering solenoid valve 25b is stopped to stop the operation of the lowering plunger pump 21b, and at the same time, the raising solenoid valve 25a is operated as described below. The ascending plunger pump 21a is operated. First, the ascent solenoid valve 25a
Is moved from the position (b) to the position (a), the piston 24a supplies oil for one stroke of the piston 24a from the reservoir tank 27 to the hydraulic chamber 22a via the first check valve 31 and the pipeline 30. Inhale. Next, the piston 24a discharges one stroke of oil in the hydraulic chamber 22a by moving the ascent solenoid valve 25a from the position (a) to the position (b). The discharged oil is sent to the buffer hydraulic cylinder 10 via the pipe line 32, the second check valve 33, and the pneumatic oil tank 13, and raises the buffer piston 12 by a certain amount. One cycle at the time of ascending is completed by the above series of operations.

That is, every time the piston 24a is operated by one stroke, a fixed amount of oil is discharged, and the height of the buffer piston 12 can be raised by a predetermined distance. Therefore, the rising distance of the buffer piston 12 can be adjusted by the number of times of operation of the ascending solenoid valve 25a, so that the height of the buffer piston 12 can be digitally adjusted with high precision. The ascending plunger pump 21a functions as a fixed-rate discharge unit.

In order to lower the buffer piston 12, similarly, the operation of the ascending solenoid valve 25a is stopped to stop the operation of the ascending plunger pump 21a, and at the same time, as described below, By operating the valve 25b, the lowering plunger pump 21b is operated. First,
By moving the lowering solenoid valve 25b from the position (a) to the position (b), the piston 24b
From 0, the oil for one stroke of the piston 24b is sucked into the hydraulic chamber 22b through the air oil tank 13, the fourth check valve 37, and the pipeline 36. At this time, the buffer piston 12
Drops by a certain amount. Next, by moving the lowering solenoid valve 25b from the position (b) to the position (a), the piston 24b discharges oil for one stroke in the hydraulic chamber 22a, and the discharged oil is discharged to the third position. It is returned to the reservoir tank 27 via the check valve 35 and the pipeline 34. With the above series of operations, one cycle at the time of descending is completed.

That is, every time the piston 24b is operated for one stroke, a certain amount of oil is sucked, and the height of the buffer piston 12 can be lowered by a predetermined distance.
Therefore, the descending distance of the buffer piston 12 can be adjusted by the number of times of operation of the descending solenoid valve 25b, so that the height of the buffer piston 12 can be digitally adjusted with extremely high precision. The lowering plunger pump 2
1b functions as a fixed amount discharging means.

Next, a method of controlling breakthrough of a press machine according to the present invention will be described with reference to FIG. FIG. 3 is a control flowchart showing an example of the present breakthrough buffer control method. Here, each step number is represented by adding S. In general, the result is to find an optimum buffer position that minimizes or maximizes the evaluation value of the breakthrough evaluation signal, but the problem of maximization can also be minimized by changing the setting of the evaluation value. Is equivalent to the problem of Therefore, in the following description, the evaluation condition for optimizing the position of the buffer piston 12 during the breakthrough buffering is to minimize the evaluation value of the breakthrough evaluation signal for each shot. Therefore, as the breakthrough evaluation signal, the bolster 5 as in this embodiment is used.
When the vibration acceleration signal is adopted, for example, a difference value between the maximum value and the minimum value of the acceleration signal (hereinafter referred to as acceleration PP value) can be used as the evaluation value. Further, the maximum value of the acceleration signal or the noise signal at the time of breakthrough may be used as the evaluation value.

In S1, the control device 40 moves the buffer piston 12 of the buffer hydraulic cylinder 10 to the search origin when the power is turned on. Here, the search origin is the lowest point position of the buffer piston 12, and the lower end of the guide post 4 and the buffer piston at the search origin position when the slide 1 of the press machine is at the bottom dead center. The clearance (gap) with the upper end of the line 12 is set to be a predetermined distance. The clearance distance is set to be small (for example, about 1 to 3 mm) so that the guide post 4 and the buffer piston 12 do not buffer at the search origin and that the search is completed in a short time at the time of the automatic search. .

Thereafter, the automatic search for the optimum buffer position of the buffer piston 12 is started from S2. As a preparation, first, in S2, it is determined whether or not the slide speed is stable. Here, the slide speed can be calculated using, for example, the signal of the rotary cam, that is, the slide speed can be calculated based on the time during which the slide 1 passes through a predetermined angular range of the rotary cam. Control device 40
Calculates the slide speed at the continuous predetermined number of shots Q, and calculates the slide speed B at the start of the automatic search by averaging Q times. Then, it is determined whether or not the calculated slide speed B is within a predetermined range according to the specifications and operating conditions of the press machine. If the slide speed B is within the predetermined range, the process proceeds to S3, If not, the process of S2 is repeated until the slide speed B becomes stable.

Next, at S3, the control device 40 inputs the above-mentioned breakthrough evaluation signal (here, acceleration signal) at the search origin at the time of no buffering. Here, when the slide 1 passes through a predetermined crankshaft angle range including the bottom dead center, the control device 40 inputs a breakthrough evaluation signal for each shot at the time of the automatic search. That is, the rotation angle of the crankshaft of the slide 1 is 180 ° (corresponding to the bottom dead center)
When the acceleration signal is within a predetermined angle range (for example, 160 ° to 190 °), the acceleration signal is input to evaluate the magnitude. At this time, since the acceleration signal of the bolster acceleration sensor 18 is usually an analog signal, the timing of A / D conversion of the acceleration signal is commanded by a signal of the rotary cam or the like that is turned on within the above-mentioned predetermined angle range.

Then, in S3, the acceleration signals at the time of no buffering are inputted for N0 shots, and the average acceleration data for the N0 shots is calculated. In this case, N0 is a natural number of 1 or more, and the larger the value of N0, the smaller the influence of data variation. However, the number of shots to be consumed increases with this. Then, an acceleration PP value with respect to the average acceleration data is obtained, and the obtained acceleration PP value is stored as reference data of an evaluation value in a subsequent automatic search. The time when the maximum value and the minimum value occur with respect to the average acceleration data at the time of no buffering is stored as an expected breakthrough occurrence time. The breakthrough occurrence time defines a search range of the acceleration PP value with respect to the acceleration data at each shot in a subsequent automatic search and a check range of the hydraulic pressure of the buffer hydraulic cylinder 10, whereby, for example, the die Can be distinguished from the acceleration of vibration at the time of touching, and the contact between the buffer hydraulic cylinder 10 and the guide post 4 can be detected.

Then, at S4, the control device 40 outputs a command signal for raising the buffer piston 12 from the current position by a first predetermined distance, for example, 1 mm. That is, the lowering solenoid valve 25b is stopped while being at the position (a),
The ascending solenoid valve 25a is switched between the (a) position and the (b) position by a predetermined number of cycles corresponding to the rising distance (here, 1 mm) of the buffer piston 12. As a result, a predetermined amount of oil is cyclically discharged from the ascending plunger pump 21a, sent to the buffer hydraulic cylinder 10 via the pneumatic oil tank 13, and the buffer piston 12 is raised by 1 mm. Next, in S5, the hydraulic pressure sensor 1
7, a hydraulic pressure maximum value is obtained by, for example, peak-holding the signal, and it is determined whether or not the hydraulic maximum value is equal to or greater than a predetermined value (eg, 120 kg / cm ² ). When the maximum value of the hydraulic pressure is less than 120 kg / cm ² , the process returns to S4 and returns to S4 until it becomes 120 kg / cm ² or more.
Is repeated, and when it is 120 kg / cm ² or more, the processing shifts to S6.

Next, in S6, the control device 40 determines whether or not the acceleration PP value at the current position of the cushioning piston 12 is equal to or less than a predetermined value A with respect to the reference data (acceleration PP value when there is no cushioning). . Here, the predetermined value A is set as a value smaller than the reference data.
% "Can be set at a predetermined ratio to the reference data. When the acceleration PP value is larger than the predetermined value A in S6, a command signal for raising the buffer piston 12 from the current position by a third predetermined distance smaller than the first distance, for example, 200 μm is output in S7, Returning to S6, the above processing is repeated. At this time, in the same manner as described above, the ascending solenoid valve 25a is switched between the position (a) and the position (b) by a predetermined number of cycles corresponding to the rising distance of the buffer piston 12 of 200 μm.
2 rises 200 μm. If the acceleration PP value at this time is equal to or smaller than the predetermined value A with respect to the reference data in S6, the acceleration PP value is stored as the minimum value, and the position of the corresponding cushioning piston 12 is stored.
Move to In S6, the acceleration PP value at each position of the shock absorbing piston 12 is obtained with respect to the average value of the acceleration data for N1 (N1 is a natural number of 1 or more) shots at each position. The same applies to the description.

At S8, the control device 40 sets the buffer piston 12
Is smaller than the third distance from the current position.
A command signal for increasing the distance by a predetermined distance, for example, 50 μm is output. At this time, the ascending solenoid valve 2 is
5a is switched between the position (a) and the position (b) by a predetermined number of cycles corresponding to the rising distance of the buffer piston 12 of 50 μm, whereby the buffer piston 12 is raised by 50 μm. Next, in S9, when the acceleration PP value at this time is equal to or less than the minimum value obtained so far, the acceleration PP value is stored as a new minimum value, and the corresponding position of the buffer piston 12 is stored. The acceleration P at this time
If the P value is larger than the minimum value, it is determined whether or not each current state satisfies the optimum position determination condition. If not, the process returns to S8 to repeat the processing.
The process proceeds to S10, where the position of the buffer piston 12 that has shown the minimum value of the acceleration PP value searched so far is determined as the optimal buffer position, and the buffer piston 12 is moved to this position.

Here, the above-mentioned optimum position determination condition means that one of the following two conditions is satisfied.
The first condition is when the minimum value of the acceleration PP value obtained so far cannot be updated even if the minimum value is increased by a second predetermined distance continuously M times from the position where the minimum value occurs. Note that M is a natural number of 2 or more. At this time, it is determined that the buffer piston 12 has risen too far from the position indicating the optimal buffer position. The second condition is when the following expression 1 is satisfied. “Equation 1” (reference data−minimum value) × α> [reference data−
(Acceleration PP value at current position) Here, α is a predetermined value between 0 and 1. That is, the reference data and the acceleration PP at the current position of the cushion piston 12
The difference from the value is the reference data and the acceleration PP determined so far.
When the difference from the minimum value is smaller than α times, the acceleration PP value at the current position is too large than the minimum value. Similarly, it is determined that the cushioning piston 12 has risen too much from the optimal cushioning position. Is determined. Here, when α is set to a value close to 1, it is easy to reach a local minimum value different from the minimum value, and when α is set to a value close to 0, the time to determine the optimum buffer position tends to be long. . Therefore, α is set to a predetermined value that allows the minimum value to be searched technically for the characteristics of the press machine, the type of work, and the like.

After S10, a monitoring routine at the optimum buffer position is entered from S11. In S11, first, the control device 40 inputs acceleration data together with a rotary cam signal for each shot, calculates a slide speed at this time based on the signal of the rotary cam in the same manner as described above, and determines the slide speed at the start of the automatic search. It is determined whether or not the slide speed B is within a predetermined value. If the slide speed does not fall within the predetermined value, that is, if the slide speed is not stable, the acceleration data input at this time is discarded, and S1
Returning to the processing of step 1, input again and repeat until the slide speed becomes stable. When the slide speed is within a predetermined value, that is, when the slide speed is stable, the acceleration data for N2 shots (N2 is a natural number of 1 or more) taken during this time is averaged by N2 times. Is calculated. Next, in S12, a monitoring threshold check is performed on the average acceleration data calculated in S11. That is, it is checked whether the following Expression 2 is satisfied. “Equation 2” (reference data−minimum value) × β> [reference data−
(Acceleration PP value with respect to N2 average acceleration data)] Here, β is a predetermined value between 0 and 1 and is set according to the frequency of re-exploration from the optimal buffer position. Increases the frequency of re-exploration. If the monitoring threshold check is OK in S12, that is, if the above formula is not satisfied, it is determined that the acceleration PP value does not exceed the monitoring threshold, and the monitoring processing at the optimal buffer position is repeated in S11.

If the above equation 2 is satisfied in S12, it is determined that the acceleration PP value exceeds the monitoring threshold, and in S13, at least two positions above and below the optimum buffer position of the buffer piston 12 are centered. , At least K positions (K is 5 or more) are set as re-search positions. FIG. 4 shows the re-search position set at this time. Each position is set at a position separated by a predetermined distance L1 such that a minimum value of the acceleration PP value is found near the current position. In step S14, the buffer piston 12 is sequentially moved to the K positions, and average acceleration data of N3 (N3 is a natural number of 1 or more) shots is obtained at each position, and based on the average acceleration data. An acceleration PP value for each position is calculated. Further, these K accelerations P
The minimum value among the P values (this is called a temporary minimum value)
A piston position showing this temporary minimum value is obtained. And
When a temporary minimum value is shown at a position other than the upper end or the lower end of the K position, the position is set as the optimal buffer position. On the other hand, when the temporary minimum value is shown at the upper end or the lower end of the K position, there is a possibility that there is a position showing the true minimum value above or below this, respectively. Therefore, when the position indicating the temporary minimum value is, for example, the upper end (lower end), the upper end (lower end)
The buffer piston 12 is moved further upward (downward) to a position separated by a predetermined distance L1, the acceleration PP value is obtained in the same manner as described above, and this acceleration PP value is compared with the temporary minimum value. Then, in the same manner as in the processing from S8 to S9, the buffer piston 12 is sequentially moved by a predetermined distance L1 to obtain a new minimum value (that is, a minimum value) and its position.

Next, in S15, it is determined whether or not the obtained minimum value satisfies the following equation (3). “Equation 3” (reference data−minimum value) × δ <(reference data−
(Minimum value) Here, δ is a predetermined value of 0 to 1. When Expression 3 is satisfied, the position indicating the minimum value in S16 is regarded as the new optimum buffer position, the position is moved to this position, the minimum value is updated as the new minimum value, and the process returns to S11 to repeat the above processing. If the formula 3 is not satisfied in S15, the buffer piston 12 is moved to the search origin in S17, and the process returns to S2 to start the automatic search again from the beginning.

When the buffer piston 12 is sequentially moved to the K position in S14, or when the buffer piston 12 is moved down to the new optimum buffer position in S16, the control device 40 is controlled by the controller 40. A command signal for lowering by a predetermined distance is output. That is, the ascending solenoid valve 25a is stopped in the position (b), and the descending solenoid valve 25b is stopped.
Is switched between the position (b) and the position (a) by a predetermined number of cycles corresponding to the predetermined distance. As a result, a predetermined amount of oil is discharged from the buffer hydraulic cylinder 10 by the descending plunger pump 21b and returned to the reservoir tank 27. As a result, the buffer piston 12 can move down a predetermined distance.

As described above, at the beginning of the automatic search for the optimum buffer position, it is checked that the magnitude of the hydraulic pressure of the buffer hydraulic cylinder 10 is equal to or greater than a predetermined value. To a larger distance (for example, 1
mm), the buffer piston 12 can exceed the clearance distance at the bottom dead center in a short time, and the contact between the buffer hydraulic cylinder 10 and the guide post 4 can be reliably accelerated. As a result, it is possible to approach the optimal buffer position with a small number of shots. Further, the search pitch when approaching the buffer piston 12 to the optimal buffer position is:
Subdivide into several stages (three stages in the example above)
At the beginning of the search, the search pitch is coarse, and the search pitch is gradually reduced as it approaches the optimum buffer position. Therefore, automatic exploration with a small number of shots is possible. At this time, since the buffer piston 12 is accurately positioned digitally, the optimum buffer position can be searched for with high accuracy in a short time.

In the above embodiment, in the monitoring process at the optimal buffer position, when the slide speed is not stable, the process is repeated until the slide speed becomes stable. However, the present invention is not limited to this method. May be. For example, when it is determined that the slide speed is not stable more than R times (R is a natural number of 2 or more) continuously, a new current slide speed B (for example, an average value of Q shots) is newly calculated, and the new slide speed B is calculated. The stability may be checked based on the slide speed B. Further, thereafter, the reference data of the evaluation value of the breakthrough evaluation signal corresponding to the new slide speed B and the expected breakthrough occurrence time may be obtained, and the monitoring threshold value may be checked based on these data.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a press machine that implements a breakthrough buffer control method according to the present invention.

FIG. 2 is a hydraulic circuit diagram for implementing a breakthrough buffer control method according to the present invention.

FIG. 3 is a flowchart illustrating an example of a breakthrough buffer control method according to the present invention.

FIG. 4 is an explanatory diagram of a re-search position near an optimum buffer position according to the present invention.

[Explanation of symbols]

 4 Guide Post 10 Buffer Hydraulic Cylinder 12 Buffer Piston 13 Air Oil Tank 14 Air Chamber 15, 34, 36 Pipeline 16 Crankshaft Angle Sensor 17 Hydraulic Sensor 18 Bolster Acceleration Sensor 20 Hydraulic Device 21a Plunger Pump for Upward 21b Plunger Pump for Downward 22a , 22b Hydraulic chamber 23a, 23b Air chamber 24a, 24b Piston 25a Elevating solenoid valve 25b Descent solenoid valve 26 Factory air 27 Reservoir tank 31 First check valve 33 Second check valve 35 Third check valve 39 Fourth check valve 40 Control device

Claims (6)

[Claims] 1. A buffer piston (12) of a buffer hydraulic cylinder (10) provided below a slide of a press machine is moved to a search origin before an automatic search for an optimum buffer position is started, and unbuffered at the search origin. Input the breakthrough evaluation signal at the time of press punching, stores the evaluation value of the breakthrough evaluation signal without buffering as reference data, and predicts the breakthrough occurrence time calculated based on this reference data. Then, the buffer piston (12) is raised by a predetermined distance at the time of automatic exploration, and based on the breakthrough evaluation signal input near the expected breakthrough occurrence time at the time of punching the press at each piston position. Calculating the evaluation value, the minimum value of the evaluation value when the difference between the calculated evaluation value and the reference data is the largest, and the minimum value In the break-through buffer control method of a press machine for automatically exploring an optimal buffer position of a shock-absorbing piston (12) and moving the buffer piston (12) to the optimal buffer position to buffer break-through, At the beginning of the start, the buffer hydraulic cylinder (1
The buffer piston (12) is raised by a first predetermined distance until the maximum value of the oil pressure of (0) becomes equal to or more than a predetermined value, and then the buffer piston is reduced by a second predetermined distance smaller than the first predetermined distance. When the piston (12) is raised, the automatic search is performed at each piston position during this time, and when the optimum position determination condition is satisfied, the buffer piston (12) is moved to the optimum buffer position determined by the automatic search. Characteristic method of controlling breakthrough of press machine. 2. The breakthrough buffer control method for a press machine according to claim 1, wherein when the maximum value of the hydraulic pressure of the buffer hydraulic cylinder (10) becomes equal to or more than the predetermined value, the first predetermined value is then set. The automatic exploration is performed by raising the buffer piston (12) by a third predetermined distance smaller than the distance and larger than the second predetermined distance, and evaluating the breakthrough evaluation signal at each piston position. The value is a predetermined value A with respect to the reference data.
A breakthrough buffer control method for a press machine, wherein the buffer piston (12) is raised by the second predetermined distance after the following. 3. The break-through buffer control method for a press machine according to claim 1, wherein the optimum position determination condition is a predetermined number of times from a position of the buffer piston (12) at which the minimum value of the evaluation value occurs. When the minimum value cannot be updated even if the distance is continuously increased by the second predetermined distance, or the difference between the reference data and the evaluation value at the current position is the difference between the reference data and the minimum value. A breakthrough buffer control method for a press machine, wherein at least one of the differences is smaller than a predetermined value times the difference. 4. An optimal buffer of a buffer piston (12) of a buffer hydraulic cylinder (10) provided below a slide of a press machine so that an evaluation value of a breakthrough evaluation signal at the time of press punching becomes a minimum value. In the breakthrough buffer control method of the press machine for automatically exploring the position and moving to this position and monitoring the change of the evaluation value at the optimal buffer position, the evaluation value at the optimal buffer position is smaller than the minimum value. Monitoring whether it is equal to or more than a predetermined monitoring threshold value, and when it is equal to or more than the monitoring threshold value, at least two locations above and below the optimum buffer position, at least five piston locations at a total of at least five locations. Automatic re-exploration of the temporary minimum value of the evaluation value and the piston position corresponding to this minimum value, and thereafter, the temporary minimum value is shown at the upper end or lower end of the plurality of piston positions. The piston position indicating the minimum value of the evaluation value by moving the buffer piston (12) further by a predetermined distance above the upper end indicating the temporary minimum value or below the lower end indicating the temporary minimum value. Automatically re-exploring and moving the buffer piston (12) to a new optimal buffer position using the piston position as a new optimal buffer position. 5. The break-through buffer control method for a press machine according to claim 4, wherein, when monitoring at said optimum buffer position, said minimum value and said minimum value at a plurality of said piston positions centering on said optimal buffer position. When automatically re-exploring the piston position corresponding to the value, if the minimum value is equal to or more than a predetermined value with respect to the minimum value at the optimal buffer position, the buffer piston (12) is moved before the automatic search starts. The automatic search is performed from the beginning after moving to the search origin at the time of no buffering, and when the minimum value is smaller than a predetermined value with respect to the minimum value, the piston position corresponding to the minimum value is set to a new optimal buffer. A breakthrough buffer control method for a press machine, wherein the buffer piston (12) is moved to a new optimal buffer position as a position. 6. The breakthrough buffer control method for a press machine according to claim 4, wherein, when the slide speed of the press machine exceeds a predetermined range at the time of monitoring at the optimal buffer position, the break inputted at this time. A breakthrough buffer of a press machine, wherein the through evaluation signal data is discarded, a breakthrough evaluation signal is input after the slide speed is stabilized again, and the monitoring threshold value check is performed based on the breakthrough evaluation signal. Control method.