Press system, press device, press control method, and press control program

Abstract

The present invention comprises: a press device including a crankshaft and a slide that moves up and down in accordance with the rotation of the crankshaft, wherein the press device performs press processing on a workpiece by using a mold attached to the slide; a control unit that controls the press device; and a storage unit that stores reference data including information relating to the correspondence relationship between the position of the slide during the press processing on the workpiece and the load applied to the slide, wherein the control unit is configured to calculate a predicted peak load on the basis of the actual load applied to the slide and the reference data during the press processing, and execute an emergency stop of the press device when the predicted peak load exceeds an upper limit load.

Description

Press system, press device, press control method, and press control program

[0001] The present invention relates to a press system, a press device, a press control method, and a press control program.

[0002] Conventionally, there is a press system including a detection unit that detects a press load when pressing a workpiece, a reference waveform generation unit that generates a reference waveform serving as a comparison target based on the waveform when the load waveforms of the press load detected by the detection unit are the same waveform a plurality of times, and a determination unit that determines whether there is a press abnormality based on the load waveform of the press load and the reference waveform (for example, Patent Document 1).

[0003] The press system described in Patent Document 1 includes a press machine, and the press machine includes a slide and a bolster. In the press machine, dies for processing a workpiece are mounted on the lower surface of the slide and the upper surface of the bolster facing the slide, and the slide 20 is lowered for press working.

[0004] Japanese Patent Application Laid-Open No. 2004-174591

[0005] Conventionally, in a press machine, an excessive pressing force generally occurs in the slide, and a device for protecting the press machine, such as an OLP (Over Load Protector), is provided to prevent the press machine from being damaged. However, these protection devices detect and protect the press machine when an overload actually occurs in the press machine, and there is a need to predict the occurrence of an overload and prevent the occurrence of an overload beforehand.

[0006] One aspect of the present invention is a press system, a press device, a press control method, and a press control program capable of preventing an overload.

[0007] A press system according to one aspect of the present invention includes a crankshaft and a slide that moves up and down in accordance with the rotation of the crankshaft, and a press device that performs press processing on a workpiece using a die mounted on the slide, a control unit that controls the press device, and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press processing and the load applied to the slide, wherein the control unit is configured to calculate a predicted peak load based on the actual load applied to the slide and the reference data during press processing, and to perform an emergency stop of the press device if the predicted peak load exceeds the upper limit load.

[0008] A press apparatus according to one aspect of the present invention comprises a crankshaft, a slide that moves up and down in accordance with the rotation of the crankshaft, a control unit that controls press working on a workpiece by a die mounted on the slide, and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide. The control unit is configured to calculate a predicted peak load based on the actual load applied to the slide and the reference data during press working, and to emergency stop the press working if the predicted peak load exceeds the upper limit load.

[0009] In one aspect of the present invention, a press control method is provided for a press apparatus comprising a crankshaft, a slide that moves up and down in accordance with the rotation of the crankshaft, a control unit that controls press working on a workpiece by a die mounted on the slide, and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide. The control unit calculates a predicted peak load based on the actual load applied to the slide and the reference data during press working, and if the predicted peak load exceeds the upper limit load, it emergency stops the press working.

[0010] A press control program according to one aspect of the present invention is a press device comprising a crankshaft, a slide that moves up and down in accordance with the rotation of the crankshaft, a control unit that controls press working on a workpiece by a die mounted on the slide, and a storage unit that stores reference data including information on the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide. The control unit calculates a predicted peak load based on the actual load applied to the slide and the reference data during press working, and if the predicted peak load exceeds the upper limit load, it emergency stops the press working.

[0011] According to one aspect of the present invention, a press system, press device, press control method, and press control program, the predicted peak load is calculated during press working, and if the predicted peak load exceeds the upper limit load, the press device is stopped in an emergency, thereby preventing overload.

[0012] According to one aspect of the present invention, a press system, a press control method, and a press control program can prevent overloading.

[0013] Figure 1 is a schematic diagram showing a press system according to an embodiment of the present invention. Figure 2 is a cross-sectional view showing the press device of this embodiment. Figure 3 is a diagram showing the operation of the slide of this embodiment. Figure 4 is a diagram showing an example of the change in slide position and load of this embodiment. Figure 5 is a diagram showing an example of the change in slide speed of this embodiment. Figure 6 is a functional block diagram showing a part of the press system of this embodiment. Figure 7 is a block diagram of the control device of this embodiment. Figure 8 is a schematic diagram showing an example of the motion program of this embodiment. Figure 9 is a diagram showing an example of the calculation of the predicted peak load of this embodiment. Figure 10 is a diagram showing an example of the load change during emergency stop of this embodiment. Figure 11 is a flowchart showing an example of the press control method of this embodiment.

[0014] The best embodiment for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments are not intended to limit the invention as described in each claim, and not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0015] [Overall Configuration of the Press System According to This Embodiment] Figure 1 is a schematic diagram showing a press system according to an embodiment of the present invention. First, with reference to Figure 1, the press system 1 according to an embodiment of the present invention will be outlined. The press system 1 according to this embodiment generally includes a press device 10, as shown in Figure 1. The press system 1 also includes a control device 100 that controls the press device 10. In this embodiment, the control device 100 is configured as part of the press device 10. However, it is not limited to this, and the control device 100 may be provided as a separate device from the press device 10.

[0016] Figure 2 is a cross-sectional view showing the press apparatus of this embodiment. The press apparatus 10, as shown in Figure 2, generally includes a crankshaft 16 and a slide 20 that moves up and down in accordance with the rotation of the crankshaft 16. The press apparatus 10 also includes a main frame 2, a bed 4, a bolster 5, and a control panel 6, as shown in Figure 1.

[0017] As shown in Figure 1, the press device 10 has a slide 20 mounted in the center of the main frame 2 that can move up and down. The press device 10 also has a bed 4 at the bottom of the main frame 2. A bolster 5 is mounted on the bed 4, facing the slide 20. Furthermore, the press device 10 has a control device 100 to which a control panel 6 is connected, mounted on the side of the main frame 2.

[0018] The upper die (punch in this embodiment) 22A of the die 22 for processing the workpiece W is detachably mounted on the lower surface of the slide 20. The lower die (die in this embodiment) 22B of the die 22 is detachably mounted on the upper surface of the bolster 5. The press device 10 is configured to perform press processing by placing the workpiece W in the lower die 22B and lowering the upper die 22A together with the slide 20.

[0019] Specifically, as shown in Figure 2, the press device 10 has a crankshaft 16 rotatably mounted above the slide 20, extending in the front-rear direction of the main frame 2. The crankshaft 16 has an eccentric portion 16e that is offset vertically. The upper end of the upper connecting rod 15 is rotatably connected to the eccentric portion 16e of the crankshaft 16, and the upper end of the lower connecting rod 17 is connected to the lower end of the upper connecting rod 15. The lower end of the lower connecting rod 17 is rotatably connected to a part of the slide 20.

[0020] In this embodiment, the press device 10 is a servo press, and a servo motor 19 is provided within the main frame 2 to rotate a crankshaft 16 and raise and lower the slide 20. A drive gear 21 is provided on the output shaft 19s of the servo motor 19, and a driven gear 23 that meshes with the drive gear 21 is provided at the rear end of the crankshaft 16. In addition, an encoder 25 for detecting the rotational speed of the output shaft 19s of the servo motor 19 is provided at the rear end of the servo motor 19.

[0021] The press device 10, having the above configuration, rotates the crankshaft 16 via the drive gear 21 and driven gear 23 by the drive of the servo motor 19, and moves the slide 20 up and down (up and down), thereby processing the workpiece W through the cooperation of the upper die 22A and the lower die 22B.

[0022] Figure 3 shows the operation of the slide in this embodiment. The slide 20 moves up and down in accordance with the rotation of the crankshaft 16, approaching and moving away from the bolster 5 as shown in Figure 3. In this embodiment, the slide 20 moves from the top dead center position (starting position), which is furthest from the bolster 5, to the bottom dead center position, which is closest to the bolster 5, during one rotation of the crankshaft 16. The height from the top surface of the bolster 5 to the bottom surface of the slide 20 when the slide 20 is in the bottom dead center position is called the die height. The die height is adjustable by driving an auxiliary motor (not shown) attached to the slide 20, which rotates a ball screw (not shown) via a worm gear (not shown), and changing the length of the lower connecting rod 17 in accordance with the rotation of the ball screw.

[0023] The user can manually adjust the die height up or down by operating the control panel 6. The press device 10 may also have an automatic die height adjustment function. If it has an automatic adjustment function, the user sets a target die height and starts the automatic adjustment, at which point the press device 10 automatically adjusts the die height to the target die height.

[0024] In this embodiment, the press system 1 includes an encoder, a linear scale, etc., for the press device 10 to detect changes in die height, and the control unit 130 of the control device 100 is configured to recognize the die height value in real time. With such a configuration, the control unit 130 can determine whether or not the die height has been adjusted. However, it is not limited to this, and the control unit 130 may also determine that the die height has been adjusted by inputting the die height value when the user adjusts the die height.

[0025] The press working of the press device 10 is set by a motion program 142, which will be described later. The angle of the crankshaft 16 at which processing begins (in this embodiment, the processing start angle) and the angle of the crankshaft 16 at which processing ends (in this embodiment, the processing end angle) are set in advance. In this embodiment, the range from the processing start angle to the processing end angle is called the processing angle. The processing angle is, for example, 90 degrees to 270 degrees, 120 degrees to 240 degrees, etc.

[0026] Figure 4 shows an example of the change in slide position and load in this embodiment. In this embodiment, the height position of the slide 20 when the angle of the crankshaft 16 is the machining start angle is preset as the machining start position, as shown in Figure 4. Similarly, the height position of the slide 20 when the angle of the crankshaft 16 is the machining end angle is preset as the machining end position. In this embodiment, the section in which the height position of the slide 20 moves from the machining start position to the machining end position is called the machining region. The machining region includes the bottom dead center position.

[0027] Figure 5 shows an example of the speed change of the slide in this embodiment. The motion program 142 has target speeds set for each height position of the slide 20, and the slide 20 moves vertically with speed changes as shown in Figure 5, driven by the servo motor 19. For example, the slide 20 starts moving from the starting position, reaches the approach speed, and then decelerates to the machining speed before moving to the machining start position. Then, the slide 20 moves in the machining area from the machining start position to the machining end position while maintaining the machining speed. After that, the slide 20 accelerates again to the approach speed, then decelerates and stops in the process of returning to the starting position. Note that the speed change of the slide 20 shown in Figure 5 is a simplified representation, and in reality, it changes continuously.

[0028] Furthermore, a load is generated on the slide 20 from the moment the upper die 22A contacts the workpiece W at the machining start position, and the load on the slide 20 increases in the machining area. Generally, the load on the slide 20 is maximum near the bottom dead center position (referred to as the peak load in this embodiment), and then decreases.

[0029] The control panel 6 is used to input various data necessary for controlling the press device 10. It has an input function for inputting data and a display function for displaying settings and data output from the press device 10. In other words, the control panel 6 functions as the input unit 110 and display unit 120 of the control device 100.

[0030] The input unit 110 is comprised of input devices such as a keyboard, touchpad, or joystick. By operating the input unit 110, in addition to the information input functions normally required by the control device 100, operations such as inputting and selecting motion programs 142 can be performed.

[0031] The display unit 120 has a display as a display device. The display unit 120 may also be configured as a touch panel (Touch screen) having the functions of the input unit 110. If the display unit 120 is configured as a touch panel, the user can, for example, perform various operations on the control device 100, such as inputting or selecting motion programs 142, by operating the display unit 120.

[0032] Figure 6 is a functional block diagram showing a part of the press system of this embodiment. The control device 100 is a PLC (Programmable Logic Controller), PC (Personal Computer), NC (Numerical Controller), etc., and as shown in Figure 6, it comprises a control unit 130 that controls the press device 10 and a storage unit 140. The control device 100 controls the servo motor 19, etc.

[0033] Furthermore, the control device 100 is connected to an encoder 25 and a servo amplifier 31 that controls the current to the servo motor 19. A power supply unit 35 that supplies power to the servo motor 19 and the like is connected to the servo amplifier 31, and a capacitor 37 is connected to the power supply unit 35. In addition, a strain gauge 41 is connected to the control device 100 via an amplifier 43.

[0034] As shown in Figure 1, the strain gauge 41 is attached to the main frame 2 and measures the elongation of the main frame 2 with the tensile direction of the main frame 2 being positive. However, it is not limited to this. The strain gauge 41 may also be attached to the upper connecting rod 15 and measure the contraction of the upper connecting rod 15 with the compression direction of the upper connecting rod 15 being positive.

[0035] Figure 7 is a block diagram of the control device of this embodiment. The control unit 130 is composed of, for example, a motion controller having a CPU (Central Processing Unit). As shown in Figure 7, the control unit 130 also includes a motion program generation unit 131, a motion calculation unit 133, a motor control unit 137, and a load calculation unit 139. In this embodiment, the control unit 130 has a look-ahead function and is configured to look ahead of some of the unprocessed command points of the motion program 142.

[0036] The motion program generation unit 131 generates a motion program 142 (motion pattern) for the slide 20 based on the input motion data. The motion program 142 has command points for changes in the movement speed of the slide 20 (rotation speed of the servo motor 19). Command points are provided at least at the start of the speed change and when the target speed is reached. Preferably, command points are also provided in the middle of the start and arrival points so that the speed change of the slide 20 is smooth and follows a curve.

[0037] Figure 8 is a schematic diagram showing an example of the motion program of this embodiment. For example, as shown in Figures 4 and 5, if the slide 20 is to move from a starting position and reach a target speed, which is the approach speed, at a predetermined height position, then, as shown in Figure 8, command points (solid circles in Figure 8) are provided at the starting point when the slide 20 begins to move from the starting position and at the arrival point when the approach speed is to be reached. Additionally, an intermediate command point (dotted circle in Figure 8) is provided between these two points.

[0038] For the sake of explanation, the command points between the start time and the arrival time are referred to as intermediate command points to distinguish them from the command points at the start time and the arrival time. However, in the actual motion program 142, the intermediate command points are the same as the command points at the start time and the arrival time.

[0039] On the other hand, if the motion program 142 moves the slide 20 at a constant speed, such as in a section where the approach speed is maintained, it is not necessary to set intermediate command points in that section. Generally, since the press device 10 performs press work while maintaining a constant processing speed in the processing area, it is not necessary to set command points in the processing area of ​​the motion program 142.

[0040] However, in this embodiment, the processing area of ​​the motion program 142 has command points set at minimum control time intervals by the motion program generation unit 131. In this embodiment, the minimum control time refers to the period (calculation period, control period) during which command data can be transferred from the motion controller to the servo amplifier 31. In other words, in this embodiment, the motion program 142 has intermediate command points set at the same constant interval as the motion calculation period of the motion controller.

[0041] As described above, in the machining area, since press machining is performed while maintaining a constant machining speed, the intermediate command points set in the machining area do not include commands for speed changes. The intermediate command points set in the machining area may include commands for maintaining the machining speed, or may be dummy command points that do not include any commands. Therefore, the intermediate command points set in the machining area do not affect the operation of the press device 10, and the operation does not change depending on the presence or absence of these intermediate command points. Further, the intermediate command points set in the machining area are configured to be rewritable to commands at the time of emergency stop, as will be described later.

[0042] The motion calculation unit 133 includes a rotation angle calculation unit that calculates the rotation angle of the crankshaft 16 based on the detection signal of the encoder 25, a height position calculation unit that calculates the height position of the slide 20 at the rotation angle of the crankshaft 16 calculated by the rotation angle calculation unit, and a slide speed calculation unit, and calculates the operation (slide motion) of the slide 20 based on the motion program 142.

[0043] The motor control unit 137 is configured to control the servo motor 19 based on the calculation result of the motion calculation unit 133. For example, the motor control unit 137 controls the servo motor 19 via the servo amplifier 31 so that the rotation angle of the crankshaft 16 calculated by the rotation angle calculation unit becomes the target rotation angle. Further, the motor control unit 137 controls the servo motor 19 via the servo amplifier 31 so that the height position of the slide 20 calculated by the height position calculation unit becomes the target height position set in the motion program 142.

[0044] Furthermore, the motor control unit 137 controls the servo motor 19 via the servo amplifier 31 so that the speed of the slide 20 calculated by the slide speed calculation unit becomes the target speed set at the command point of the motion program 142 at a predetermined height position.

[0045] In this embodiment, the motor control unit 137 is configured to execute a regenerative braking process that rotates the crankshaft 16 in the reverse direction to the pressing operation on the press device 10 during an emergency stop described later. Specifically, when the command point in the processing area of the motion program 142 is rewritten to the command during an emergency stop and the control of the servo motor 19 is overridden, the motor control unit 137 reverses the rotation direction of the servo motor 19.

[0046] By reversing the rotation direction of the servo motor 19, the crankshaft 16 rotates in the reverse direction to the pressing operation, and the slide 20 decelerates. The inertial energy generated at this time is converted into electrical energy and stored in the capacitor 37 connected to the power supply unit 35. Further, the press device 10 includes a mechanical brake (not shown). In this embodiment, the press device 10 stops by using both the regenerative brake by the regenerative braking process and the mechanical brake during an emergency stop.

[0047] The load calculation unit 139 calculates the load applied to the slide 20 based on the detection signal of the strain gauge 41. In this embodiment, during the operation of the press device 10 (during pressing), the load applied to the slide 20 in the processing area is referred to as the actual load P, and the load information of the slide 20 included in the reference data 144 described later is referred to as reference load information 146 as described later. Both the actual load P and the reference load information 146 are measured values calculated by the load calculation unit 139 based on the detection signal of the strain gauge 41.

[0048] Further, the load calculation unit 139 calculates a predicted peak load Px based on the actual load P applied to the slide 20 and the reference data 144 during pressing. In this embodiment, the predicted peak load Px is an estimated value of the peak load generated near the bottom dead center as described above.

[0049] Specifically, the load calculation unit 139 is configured to identify the load change α per unit displacement and the distance from the point of actual load P generation to the peak load generation point. In this embodiment, the point of actual load P generation is the height position of the slide 20 where the actual load P is generated, calculated by the load calculation unit 139 based on the detection signal of the strain gauge 41, and is not the position where the actual load P began to be generated during the press working of the workpiece W. The peak load generation point is, as will be described later, the height position of the slide 20 where the peak load of the reference data 144 occurred.

[0050] The load calculation unit 139 calculates, for example, the load change α per unit displacement based on the actual load P. Specifically, the load calculation unit 139 calculates the load change α per unit displacement by dividing the difference between the actual load P at the first height position and the actual load P at the second height position by the amount of displacement from the first height position to the second height position.

[0051] However, the method for calculating the load change α per unit displacement is not limited to this. The load calculation unit 139 may, for example, calculate the load change α per unit displacement based on the reference data 144. For example, the load calculation unit 139 may calculate the load change α per unit displacement by dividing the difference between the first reference load information 146 at the point where the actual load P is generated and the second reference load information 146 at a height position advanced by a predetermined amount of displacement from the point where the actual load P is generated by a predetermined amount of displacement.

[0052] The load calculation unit 139 calculates the distance from the point of actual load P generation to the peak load generation point based on the reference data 144. Specifically, the peak load generation point is determined by the maximum value of the reference load information 146 in the reference data 144 (the reference load information 146 for the peak load) and the corresponding reference position information 145 (the height position of the slide 20), and the distance from the point of actual load P generation to the peak load generation point is calculated.

[0053] Figure 9 shows an example of how to calculate the predicted peak load in this embodiment. The predicted peak load Px is estimated to occur at the peak load generation point based on the reference data 144. Therefore, the load calculation unit 139 calculates the predicted peak load Px based on the actual load P, the load change α per unit displacement, and the distance from the point of actual load P generation to the peak load generation point. Specifically, the load calculation unit 139 calculates the predicted peak load Px as shown in Figure 9 by adding the product of the load change α per unit displacement and the distance from the point of actual load P generation to the peak load generation point to the actual load P.

[0054] The load calculation unit 139 is configured to emergency stop the press device 10 if the calculated predicted peak load Px exceeds the upper limit load Pmax. In this embodiment, the upper limit load Pmax is the upper limit of the load that can be applied to the slide 20 without damaging the press device 10.

[0055] In this embodiment, the load calculation unit 139 is configured to perform an emergency stop on the press device 10 by overriding the control of the servo motor 19 by rewriting the command point of the processing area in the motion program 142 to an emergency stop command when the calculated predicted peak load Px exceeds the upper limit load Pmax.

[0056] Figure 10 shows an example of load change during emergency stop in this embodiment. Specifically, the load calculation unit 139 is configured to rewrite the command points that have not yet been looked up by the look-ahead function among the multiple command points set in the processing area of ​​the motion program 142 to emergency stop commands. When the press device 10 is stopped in an emergency, as shown in Figure 10, the load on the slide 20 at the peak load generation point will be less than the upper limit load Pmax, thereby preventing damage to the press device 10.

[0057] In this embodiment, when the die height of the press device 10 is adjusted, the control unit 130 is configured to perform low-speed press processing with a crankshaft rotation speed lower than that used when press processing is performed using the reference data 144, rather than performing press processing using the reference data 144 during the first operation of the press device 10 after the adjustment.

[0058] Furthermore, the control unit 130 is configured to acquire reference data 144 corresponding to the adjusted die height during low-speed press working. The control unit 130 is also configured to perform low-speed press working and acquire the reference data 144 even if the reference data 144 is not stored in the storage unit 140.

[0059] The storage unit 140 has a storage medium such as an HDD (Hard Disk Drive) or SSD (Solid State Drive) and stores various data in a read-write manner. As shown in Figure 7, the storage unit 140 stores the motion program 142, reference data 144, and press control program 148. Furthermore, the storage unit 140 stores the programs necessary for controlling each part of the press device 10 and the control device 100.

[0060] The reference data 144 includes information relating to the position of the slide 20 on the workpiece W during press working and the load applied to the slide 20. Specifically, the reference data 144 includes information on the height position of the slide 20 (reference position information 145 in this embodiment) and information on the load applied to the slide 20 at the height position (reference load information 146 in this embodiment).

[0061] In this embodiment, the reference position information 145 is not information of a single height position, but rather information of multiple height positions acquired at predetermined intervals from the time the slide 20 starts moving from the starting position until it returns to the starting position, and the reference load information 146 is information of the load at each of these height positions. However, it is not limited to this, and the reference position information 145 and the reference load information 146 only need to include information in the machining area.

[0062] In this embodiment, the reference data 144 is acquired during low-speed press working, as described above. Specifically, the reference data 144 includes the height position of the slide 20 during low-speed press working and the load applied to the slide 20 at each height position of the slide 20 during low-speed press working.

[0063] However, the reference data 144 may be, for example, data acquired when another press machine 10 performs press working at a normal speed. Also, if the reference data 144 was acquired during low-speed press working, scaling will be performed because the time required for press working will differ from that when operating at a normal speed.

[0064] The press control program 148 controls the press apparatus 10, which comprises a crankshaft 16, a slide 20 that moves up and down in accordance with the rotation of the crankshaft 16, a control unit 130 that controls the press working on the workpiece W by a die 22 (upper die 22A in this embodiment) mounted on the slide 20, and a storage unit 140 that stores reference data 144 containing information on the correspondence between the position of the slide 20 during press working on the workpiece W and the load applied to the slide 20. During press working, the program 148 calculates a predicted peak load Px based on the actual load P applied to the slide 20 and the reference data 144, and if the predicted peak load Px exceeds the upper limit load Pmax, it performs an emergency stop on the press working.

[0065] [Press control method according to this embodiment] Figure 11 is a flowchart showing an example of the press control method according to this embodiment. Next, the press control method of the press system 1 according to this embodiment will be described with reference to Figure 11. The press control method of the press system 1 according to this embodiment is, in general terms, a press device 10 comprising a crankshaft 16, a slide 20 that moves up and down in accordance with the rotation of the crankshaft 16, a control unit 130 that controls press processing of the workpiece W by a die 22 (upper die 22A in this embodiment) mounted on the slide 20, and a storage unit 140 that stores reference data 144 containing information on the correspondence between the position of the slide 20 during press processing on the workpiece W and the load applied to the slide 20. The control unit 130 of the press device 10 calculates a predicted peak load Px based on the actual load P applied to the slide 20 and the reference data 144 during press processing, and if the predicted peak load Px exceeds the upper limit load Pmax, it emergency stops the press processing.

[0066] First, the control unit 130 of the control device 100 of the press system 1 reads the motion program 142 stored in the storage unit 140 of the control device 100. If the reference data 144 is already stored in the storage unit 140 (YES in S1 of Figure 11) and the die height of the press device 10 of the press system 1 has not been adjusted (NO in S2 of Figure 11), the control unit 130 turns off the speed limit that restricts the rotational speed of the crankshaft 16 of the press device 10 (S3 of Figure 11). Then, the control unit 130 starts the press device 10 at the normal operating speed set in the motion program 142 (S4 of Figure 11: normal operation process).

[0067] Specifically, the motion calculation unit 133 of the control unit 130 of the control device 100 reads the motion program 142 as needed and calculates the movement of the slide 20. In addition, the motor control unit 137 of the control unit 130 controls the servo motor 19 of the press device 10 via the servo amplifier 31 of the press device 10. In the press device 10, the crankshaft 16 rotates as the servo motor 19 rotates, and consequently the slide 20 moves downward from the starting position to the bottom dead center position.

[0068] Furthermore, the load calculation unit 139 of the control unit 130 of the control device 100 calculates the actual load P applied to the slide 20 based on the detection signal from the strain gauge 41 of the press device 10 (actual load calculation step). Then, the load calculation unit 139 calculates the predicted peak load Px based on the actual load P applied to the slide 20 in the processing area and the reference data 144 (S5 in Figure 11: predicted peak load calculation step). Specifically, the load calculation unit 139 calculates the predicted peak load Px based on the actual load P applied to the slide 20, the load change α per unit movement, and the distance from the point where the actual load P is generated to the point where the peak load is generated.

[0069] In this embodiment, the load calculation unit 139 of the control unit 130 of the control device 100 calculates the actual load P at predetermined intervals and calculates the predicted peak load Px each time. Preferably, the calculation of the predicted peak load Px is continued until the slide 20 reaches the height position (peak load generation point) of the slide 20 where the peak load of the reference data 144 occurred.

[0070] Furthermore, the load calculation unit 139 of the control unit 130 of the control device 100 determines whether the calculated predicted peak load Px is less than or equal to a predetermined upper limit load Pmax (S6 in Figure 11: predicted peak load determination step). If it is determined that the predicted peak load Px is less than or equal to the upper limit load Pmax (YES in S6 in Figure 11), as described above, the load calculation unit 139 repeats the predicted peak load calculation step and the predicted peak load determination step at predetermined intervals, and the press device 10 continues to press the workpiece W. If the predicted peak load Px does not exceed the upper limit load Pmax, the press device 10 completes one rotation of the crankshaft 16 and the slide 20 returns to the starting position, ending the press processing of the workpiece W (S7 in Figure 11).

[0071] The press system 1 allows for continuous operation of the press device 10, and when processing another workpiece W is to be processed immediately after the processing of the workpiece W is completed (NO in S9 of Figure 11), the press system 1 repeatedly performs the above-described process.

[0072] On the other hand, the load calculation unit 139 of the control unit 130 of the control device 100 determines that the calculated predicted peak load Px exceeds a predetermined upper limit load Pmax (NO in S6 in Figure 11), and then performs an emergency stop on the press device 10 (S8 in Figure 11: emergency stop process). Specifically, the load calculation unit 139 is configured to perform an emergency stop on the press work of the press device 10 by overwriting the command points in the processing area of ​​the currently executing motion program 142 that have not been looked up with commands for emergency stop, and by overriding the control of the servo motor 19. The press device 10 then performs an emergency stop using both regenerative braking and mechanical braking.

[0073] If the reference data 144 is not pre-stored in the storage unit 140 of the control device 100 (NO in S1 of Figure 11), or if the die height of the press device 10 was adjusted after the end of the previous production run or when continuous operation was interrupted (YES in S2 of Figure 11), the control unit 130 of the control device 100 turns on the speed limiter, which limits the rotational speed of the crankshaft 16 of the press device 10 (S10 of Figure 11). Then, the control unit 130 starts the press device 10 at a lower speed than the normal operating speed set in the motion program 142 (S11 of Figure 11: low-speed operation process).

[0074] In low-speed operation, the crankshaft 16 of the press device 10 rotates at a lower speed than when press working using the reference data 144 described above. The slide 20 of the press device 10 moves downward from the starting position at a slower speed than in normal operation. The load calculation unit 139 of the control unit 130 of the control device 100 calculates the actual load P applied to the slide 20 based on the detection signal of the strain gauge 41 of the press device 10, similar to normal operation (actual load calculation step). In this embodiment, the load calculation unit 139 calculates the actual load P at predetermined intervals. It is preferable that the calculation of the actual load P continues at least until the slide 20 has passed through the processing area.

[0075] Furthermore, the load calculation unit 139 of the control unit 130 of the control device 100 determines whether the actual load P applied to the slide 20 in the processing area is less than or equal to a predetermined allowable load (S12 in Figure 11: Actual load determination step). In this embodiment, the allowable load is set to a value smaller than the upper limit load Pmax. The allowable load is set to a value obtained by subtracting from the upper limit load Pmax a value that takes into account, for example, the braking distance that the slide 20 moves when the press device 10 is stopped in an emergency, in other words, the maximum amount that the slide 20 is pressed into the workpiece W.

[0076] If the load calculation unit 139 of the control unit 130 of the control device 100 determines that the calculated actual load P is less than or equal to the allowable load (YES in S12 of Figure 11), the load calculation unit 139 repeats the actual load calculation process and the actual load determination process at predetermined intervals, and the press device 10 continues to press the workpiece W. If the actual load P does not exceed the allowable load, the crankshaft 16 completes one rotation and the slide 20 returns to the starting position, and the low-speed press processing of the workpiece W is completed (S13 of Figure 11).

[0077] Furthermore, the control unit 130 of the control device 100 records information on the height position of the slide 20 and information on the actual load P of the slide 20 at each height position as reference position information 145 and reference load information 146, respectively, during low-speed press working, and acquires reference data 144 corresponding to the adjusted die height. The acquired reference data 144 is stored in the storage unit 140 (S14 in Figure 11: Reference data storage step).

[0078] On the other hand, if the load calculation unit 139 of the control unit 130 of the control device 100 determines that the calculated actual load P exceeds a predetermined allowable load (YES in S12 of Figure 11), it will emergency stop the press work of the press device 10, similar to when it determines that the predicted peak load Px exceeds the upper limit load Pmax during normal operation (S8 in Figure 11: emergency stop process). Through these steps, a series of press control methods by the press system 1 according to this embodiment are executed.

[0079] [Advantages of the press system, press device, press control method, and press control program according to this embodiment] As described above, the press system 1 according to this embodiment includes a crankshaft 16 and a slide 20 that moves up and down in accordance with the rotation of the crankshaft 16, and comprises a press device 10 that performs press processing on a workpiece W using a die 22 mounted on the slide 20, a control unit 130 that controls the press device 10, and a storage unit 140 that stores reference data 144 containing information on the correspondence between the position of the slide 20 on the workpiece W during press processing and the load applied to the slide 20. The control unit 130 is configured to calculate a predicted peak load Px based on the actual load P applied to the slide 20 and the reference data 144 during press processing, and to emergency stop the press device 10 if the predicted peak load Px exceeds the upper limit load Pmax.

[0080] Furthermore, the press system 1 according to this embodiment has the advantage of being able to prevent overloading by having such a configuration, which allows for the calculation of a predicted peak load Px in real time during press working based on the actual load P applied to the slide 20 and the reference data 144, and by initiating an emergency stop of the press device 10 when the predicted peak load Px exceeds the upper limit load Pmax, thereby enabling the emergency stop to be initiated before the slide 20 actually reaches the peak load generation point where the load is at its maximum.

[0081] Furthermore, the press system 1 according to this embodiment has the additional advantage that, since it can emergency stop the press device 10 when the predicted peak load Px exceeds the upper limit load Pmax, the press device 10 does not need to include protective devices such as an OLP (Oil Lap Plate), and damage to the press device 10 due to overload can be prevented even without a protective device. Also, since the press device 10 does not need to include a protective device, it is possible to miniaturize the press device 10 and reduce the cost of the press system 1. Moreover, in the case of a press device that includes an OLP, as in conventional press devices, due to the structure of the OLP, the oil inside is repeatedly compressed and expanded by the processing load, which can change the die height of the press device 10 and affect the accuracy of the press processing. However, as described above, the press device 10 according to this embodiment can prevent damage to the press device 10 even without an OLP, and therefore the accuracy of the press processing can be improved compared to conventional press devices that include an OLP.

[0082] Furthermore, in the press system 1 according to this embodiment, the control unit 130 is configured to identify the load change α per unit movement and the distance from the point of actual load P generation to the point of peak load generation. The distance from the point of actual load P generation to the point of peak load generation is calculated based on reference data 144, and the predicted peak load Px is calculated based on the actual load P, the load change α per unit movement, and the distance from the point of actual load P generation to the point of peak load generation. By having such a configuration, over-detection can be suppressed, which has the advantage of preventing overload more reliably.

[0083] Furthermore, in the press system 1 according to this embodiment, the processing area of ​​the motion program 142 of the press device 10 has command points set at minimum control time intervals, and the control unit 130 rewrites the command points of the processing area to an emergency stop command when the predicted peak load Px exceeds the upper limit load Pmax. By having such a configuration, when the predicted peak load Px exceeds the upper limit load Pmax, an emergency stop can be initiated immediately without waiting for the execution of a pre-read command, thus having the advantage of more reliably preventing overload.

[0084] Furthermore, in the press system 1 according to this embodiment, the control unit 130 is configured such that, when the die height of the press device 10 is adjusted, it does not perform press working using the reference data 144 during the first operation of the press device 10 after adjustment, but instead performs low-speed press working with the crankshaft 16 rotational speed lower than that used when press working with the reference data 144. By having such a configuration, press working is performed at the normal speed even when the reference data 144 does not correspond to the adjusted die height, which prevents the control unit 130 from calculating and making a judgment based on an incorrect predicted peak load Px, and thus has the advantage of more reliably preventing overload.

[0085] Furthermore, in the press system 1 according to this embodiment, the control unit 130 is configured to acquire reference data 144 corresponding to the adjusted die height during low-speed press working. With this configuration, the reference data 144 corresponding to the adjusted die height can be acquired by simply performing low-speed press working once after adjusting the die height. This eliminates the need for the user to adjust parameters such as those used to calculate the predicted peak load Px in accordance with the adjusted die height, and has the further advantage of allowing the system to return to normal operation in a short time even after adjusting the die height.

[0086] Furthermore, in the press system 1 according to this embodiment, the press device 10 is a servo press, and the control unit 130 causes the press device 10 to perform a power regenerative braking process that rotates the crankshaft 16 in the opposite direction to that during press work when an emergency stop occurs. By having such a configuration, it is possible to generate a strong braking force from the initial stage of an emergency stop when the rotation speed of the servo motor 19 is high, which has the advantage of being able to prevent overload more reliably.

[0087] [Modifications] Although preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the embodiments described above. Various modifications or improvements can be made to the embodiments described above.

[0088] For example, in the embodiment described above, the control unit 130 is configured to specify the load change α per unit displacement and the distance from the point of actual load P generation to the peak load generation point, and the distance from the point of actual load P generation to the peak load generation point is calculated based on reference data 144, and the predicted peak load Px is calculated based on the actual load P, the load change α per unit displacement, and the distance from the point of actual load P generation to the peak load generation point, but this is not limited to this. The control unit 130 does not need to specify the load change α per unit displacement and the distance from the point of actual load P generation to the peak load generation point. Also, the distance from the point of actual load P generation to the peak load generation point may not be calculated based on reference data 144, but rather based on the peak load generation point where the previously recorded predicted peak load Px is expected to occur. Furthermore, the predicted peak load Px does not need to be calculated based on the actual load P, the load change α per unit displacement, and the distance from the point of actual load P generation to the peak load generation point.

[0089] In the embodiment described above, the processing area of ​​the motion program 142 of the press device 10 has command points set at minimum control time intervals, and the control unit 130 is described as rewriting the command points of the processing area to an emergency stop command when the predicted peak load Px exceeds the upper limit load Pmax. However, the embodiment is not limited to this. The processing area of ​​the motion program 142 does not have command points set at minimum control time intervals. As described above, the processing area of ​​the motion program 142 does not have command points set, or it may be set at intervals of, for example, twice the minimum control time. Furthermore, when the predicted peak load Px exceeds the upper limit load Pmax, the control unit 130 may not rewrite the command points of the processing area to an emergency stop command, but simply cut off power from the power supply unit 35 to the servo amplifier 31 and then to the servo motor 19, and then emergency stop the press device 10 by dynamic braking, which converts the electromotive force of the servo motor 19 into thermal energy by flowing it through a resistor.

[0090] In the embodiments described above, the control unit 130 is configured to perform low-speed press working with a lower rotational speed than that used when performing press working with reference data 144, instead of performing press working using reference data 144, during the first operation of the press device 10 after the die height has been adjusted. However, the configuration is not limited to this. The control unit 130 may also be configured to perform press working at a normal speed, similar to that used when performing press working with reference data 144, during the first operation of the press device 10 after the die height has been adjusted, instead of performing low-speed operation.

[0091] In the embodiments described above, the control unit 130 was described as being configured to acquire reference data 144 corresponding to the adjusted die height during low-speed press working, but it is not limited to this. The control unit 130 does not need to acquire reference data 144 during low-speed press working. Alternatively, the control unit 130 may create reference data 144 corresponding to the adjusted die height by making a correction to the acquired reference data 144 stored in the storage unit 140 by offsetting the position of the die height adjustment.

[0092] In the embodiments described above, the press device 10 was described as a servo press, and the control unit 130 was described as causing the press device 10 to perform a power regenerative braking process that rotates the crankshaft 16 in the opposite direction to that during press work in the event of an emergency stop. However, the invention is not limited to this. The press device 10 may be a mechanical crank press using a flywheel instead of a servo press. Furthermore, the press device 10 does not need to perform a power regenerative braking process in the event of an emergency stop.

[0093] In the embodiments described above, the press device 10 was described on the premise that it does not include protective devices such as OLP, but it is not limited to this. The press device 10 may include protective devices such as OLP.

[0094] 1 Press system 2 Main frame 4 Bed 5 Bolster 6 Control panel 10 Press device 15 Upper connecting rod 16 Crankshaft 16e Eccentric part 17 Lower connecting rod 19 Servo motor 19s Output shaft 20 Slide 21 Drive gear 22 Mold 22A Upper mold 22B Lower mold 23 Driven gear 25 Encoder 31 Servo amplifier 35 Power supply unit 37 Capacitor 41 Strain gauge 43 Amplifier 100 Control device 110 Input unit 120 Display unit 130 Control unit 131 Motion program generation unit 133 Motion calculation unit 137 Motor control unit 139 Load calculation unit 140 Storage unit 142 Motion program 144 Reference data 145 Reference position information 146 Reference load information 148 Press control program P Actual load Pmax, Upper limit load Px, Predicted peak load W, Workpiece α, Load change per unit displacement

Claims

1. A press device comprising: a crankshaft and a slide that moves up and down in accordance with the rotation of the crankshaft, wherein a die mounted on the slide is used to press-form a workpiece; a control unit that controls the press device; and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during the press-form process and the load applied to the slide, wherein the control unit is configured to calculate a predicted peak load based on the actual load applied to the slide and the reference data during the press-form process, and to emergency stop the press device if the predicted peak load exceeds the upper limit load.

2. The press system according to claim 1, wherein the control unit is configured to identify the load change per unit displacement and the distance from the point of actual load generation to the point of peak load generation, the distance is calculated based on the reference data, and the predicted peak load is calculated based on the actual load, the load change, and the distance.

3. The press system according to claim 1 or 2, wherein the processing area of ​​the motion program of the press device has command points set for every minimum control time, and the control unit rewrites the command points of the processing area to an emergency stop command when the predicted peak load exceeds the upper limit load.

4. The press system according to claim 1 or 2, wherein the control unit is configured to, when the die height of the press device is adjusted, perform low-speed press processing in the first operation of the press device after the adjustment, by reducing the rotational speed of the crankshaft compared to that used during press processing with the reference data.

5. The press system according to claim 4, wherein the control unit is configured to acquire the reference data corresponding to the adjusted die height in the low-speed press working.

6. The press system according to claim 1 or 2, wherein the press device is a servo press, and the control unit causes the press device to perform a power regenerative braking process that rotates the crankshaft in the opposite direction to that during press working when an emergency stop occurs.

7. A press device comprising: a crankshaft; a slide that moves up and down in accordance with the rotation of the crankshaft; a control unit that controls press working on a workpiece by a die mounted on the slide; and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide, wherein the control unit is configured to calculate a predicted peak load based on the actual load applied to the slide and the reference data during press working, and to emergency stop the press working if the predicted peak load exceeds the upper limit load.

8. A press control method comprising a control unit for a press apparatus, which includes a crankshaft, a slide that moves up and down in accordance with the rotation of the crankshaft, a control unit that controls press working on a workpiece by a die mounted on the slide, and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide, wherein the control unit calculates a predicted peak load based on the actual load applied to the slide and the reference data during press working, and if the predicted peak load exceeds the upper limit load, it emergency stops the press working.

9. A press device comprising a crankshaft, a slide that moves up and down in accordance with the rotation of the crankshaft, a control unit that controls press working on a workpiece by a die mounted on the slide, and a storage unit that stores reference data including information relating to the correspondence between the position of the slide relative to the workpiece during press working and the load applied to the slide, wherein the control unit has a press control program that calculates a predicted peak load based on the actual load applied to the slide and the reference data during press working, and emergency stops the press working if the predicted peak load exceeds the upper limit load.

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