Pressing device and control method for a pressing device

Abstract

Pressing device (1) comprising: a slide (2) which is set up to mount an upper press mold (7) on it; a table (3) arranged under the carriage (2), the table (3) being configured to place a lower press mold (8) on it; a servomotor (21) which is set up to drive the carriage (2); an energy storage unit (60) configured to supply stored energy to the servomotor (21); and a current detector (61) configured to detect current supplied by the energy storage unit (60); characterized by a control unit (10) which is configured to perform a stop control in order to stop the current supply from the energy storage unit (60) to the servomotor (21) based on a detection value of the current detector (61) when it is determined that an average value of the current supplied by the energy storage unit (60) within a specific determination time has exceeded a specific threshold value.

Description

TECHNICAL AREA

[0001] The present invention relates to a pressing device and a method for controlling a pressing device. STATE OF THE ART

[0002] For example, automobile manufacturers produce body panels and similar components using a press that employs dies. In recent years, servo-motor-driven presses have been used as presses.

[0003] With such a servo-motor driven press machine, the peak power during press forming is quite high, and problems such as flickering can occur due to a voltage drop inside or outside the factory.

[0004] Meanwhile, a setup has been disclosed in which an aluminum electrolytic capacitor is installed in a press fixture to keep peak power low (see, for example, JP 2003 - 230 997 A). CITATION LIST PATENT LITERATURE

[0005] JP 2003 - 230 997 A; JP 2010 - 260 094 A; DE 10 2006 058 629 B3.

[0006] DE 10 2006 058 629 B discloses the features of the preamble of claim 1. SUMMARY TECHNICAL PROBLEM

[0007] However, if an energy storage device is used that employs an electrolyte solution, if a large current flows in a short time, the electrolyte solution may evaporate, which can degrade the storage performance (reduce the capacity, shorten the lifespan), etc.

[0008] It is an object of the present invention to provide a pressing device and a method for controlling a pressing device with which an impairment of storage capacity can be reduced. PROBLEM SOLVING

[0009] To solve the stated problem, the press device according to the invention comprises a carriage, a table, a servo motor, an energy storage unit, a current detector, and a control unit. An upper press die can be attached to the carriage. The table is arranged below the carriage, and a lower press die can be placed on it. The servo motor drives the carriage. The energy storage unit can supply the servo motor with stored electrical energy. The current detector detects the current supplied by the energy storage unit. The control unit performs a stop control to stop the current supply from the energy storage unit to the servo motor based on the current detector's reading when it is determined that the average value of the current supplied by the energy storage unit within a specific time period has exceeded a specific threshold.

[0010] Preferred embodiments are the subject of dependent claims 2 to 7.

[0011] The method for controlling a press according to the invention also includes a detection step and a stop step. The detection step involves detecting the current supplied by the energy storage unit to the servo motor driving the carriage. The stop step involves stopping the current supply from the energy storage unit to the servo motor based on the detection value in the detection step when it is determined that an average value of the current supplied by the energy storage unit within a specific time period has exceeded a specific threshold. BENEFICIAL EFFECTS

[0012] The present invention provides a pressing device and a method for controlling a pressing device, with which an impairment of storage performance can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a simplified view of a pressing device according to an embodiment of the present invention; Fig. 2 is an oblique view of the capacitor unit of the press device in Fig. 1; Fig. Figure 3 is a block diagram of the structure of the control device of the press device in Fig. 1; Fig. Figure 4 is a graph of the relationship between the excitation time of the capacitor unit in Fig. 2 and the maximum permissible current during continuous excitation; Fig. 5A is a flowchart of the control operation of the press device in Fig. 1; Fig. 5B is a flowchart of the control operation of the press device in Fig. 1; Fig. Figure 6 is a diagram of the energy supplied by a factory power supply when the press is in Fig. 1 is used; and Fig. 7 is a graph of the time change of the current from the current detector in Fig. 1 recorded current. DESCRIPTION OF EXECUTION FORMS

[0013] The pressing device of the present invention will now be described with reference to the drawings. 1. Setup 1-1. Overview of the pressing device

[0014] Fig. Figure 1 is a simplified view of the structure of a press device 1 in an embodiment of the present invention.

[0015] The press device 1 in this embodiment subjects a material to pressing using an upper press die 7 and a lower press die 8. The press device 1 mainly comprises a slide 2, a table 3, a slide drive device 4, a servo power supply unit 5, a storage system unit 6, a main disconnect switch 9 and a control device 10.

[0016] The upper press die 7 is attached to the underside of the carriage 2. The lower press die 8 is located on the top of the table 3. The carriage drive 4 moves the carriage 2 up and down. The servo power supply unit 5 converts alternating current supplied by a power supply 100 into direct current and outputs it to the storage system unit 6. The storage system unit 6 stores the renewable energy generated in the power supply 100 or the carriage drive 4. The main disconnect switch 9 switches the energy supplied to the press 1 by the power supply 100 on and off. The control device 10 controls the carriage drive 4, the servo power supply unit 5, and the storage system unit 6. 1-2. Slide drive device

[0017] The slide drive device 4 comprises a servo motor 21, a servo amplifier 22, a pinion 23, a main gear 24, a crankshaft 25, and a connecting rod 26. The servo motor 21 is the drive source for the slide 2. The servo amplifier 22 supplies the servo motor 21 with drive current. The pinion 23 is connected to the servo motor 21 and is rotated by the rotation of the servo motor 21. The main gear 24 meshes with the pinion 23 and rotates together with the pinion 23. The crankshaft 25 is connected to the main gear 24 and is rotated by the rotation of the main gear 24. The connecting rod 26 connects the crankshaft 25 and the slide 2. In this embodiment, two connecting rods 26 are provided.

[0018] When the servo motor 21 is rotated by the drive current from the servo amplifier 22, the pinion 23 rotates, and the main gear 24 also rotates together with the pinion 23. The crankshaft 25 is rotated by the rotation of the main gear 24, and the connecting rod 26 moves up and down. This causes the carriage 2, which is connected to the connecting rods 26, to move up and down. 1-3. Servo power supply

[0019] The servo power supply 5 comprises a harmonic filter module 31, an inductor 32, and a PWM converter 33. The harmonic filter module 31 prevents harmonics generated in the PWM converter 33 from returning to the factory power supply 100.

[0020] The choke 32 and the PWM converter 33 form a chopper circuit that converts alternating current to direct current and increases the voltage. Alternating current at a specific voltage is supplied from the power supply 100, and direct current at a voltage higher than this specific voltage is output by the PWM converter 33. The PWM converter 33 and the servo amplifier 22 are connected via a DC bus line 14. The PWM converter 33 also monitors the voltage on the DC bus line 14. 1-4. Storage system unit

[0021] The storage system unit 6 mainly comprises the accumulator 42, which is equipped with several electrical double-layer capacitors 601 (see Fig. 2, described below) is provided with an initial charging circuit 41, which charges the electrical double-layer capacitors 601 before operation, and a short-circuit contactor 43, which bypasses the initial charging circuit 41, and a short-circuit contactor 44, which stops the current supply from the electrical double-layer capacitors 601 to the servomotor 21. 1-4-1. Initial charging circuit

[0022] The initial charging circuit 41 is provided on the DC bus line 14 and is a circuit for charging the electrical double-layer capacitors 601 (described below) which are provided on the accumulator 42. That is, since the electrical double-layer capacitors 601 of the accumulator 42 are not charged before the pressing device 1 is actuated, they are charged with the energy supplied by the factory power supply 100. The initial charging circuit 41 has a DC / DC converter 51 and an inductor 52. The initial charging circuit 41 throttles the current so that it does not flow into the electrical double-layer capacitors 601 all at once during charging. 1-4-2. Short-circuit contactor

[0023] The short-circuit contactor 43 is provided on a bypass line 15, which is connected to the DC bus line 14 to bypass the initial charging circuit 41. That is, the bypass line 15 is connected to the DC bus line 14 on the side of the PWM converter 33 and to the DC bus line 14 on the side of the servo amplifier 22 of the initial charging circuit 41. When the short-circuit contactor 43 is switched on, the current output by the PWM converter 33 bypasses the initial charging circuit 41 and is supplied to the servo amplifier 22. 1-4-3. Accumulator

[0024] The accumulator 42 has four capacitor units 60, which are equipped with 24 electrical double-layer capacitors 601 (see Fig. 2) are provided, and four current sensors 61.

[0025] Fig. Figure 2 shows a view of a capacitor unit 60 provided on the accumulator 42. In this embodiment, the capacitor unit 60 has two heat sinks 602 and 24 electrical double-layer capacitors 601 connected in series.

[0026] The two heat sinks 602 are arranged one above the other. The capacitor unit 60 comprises one heat sink 602 and twelve double-layer capacitors 601, mounted on the heat sink 602 in two planes. The two heat sinks 602 and the twelve double-layer capacitors 601 are secured by a frame element or the like. The heat sinks 602 are plate-shaped elements made of aluminum, and channels through which cooling water flows are formed in the heat sinks 602. The cooling water is supplied from a cooler 12 to the channels of the heat sinks 602. The cooling water is circulated through the cooler 12.

[0027] In the press device 1 in this embodiment, as described in Fig. As shown in Figure 1, four capacitor units 60 are provided, and the four capacitor units 60 are connected in parallel to a line (in particular the DC bus line 14) that supplies power to the servo motor 21 from the factory power supply 100. More precisely, the four capacitor units 60 are coupled between the servo amplifier 22 and the portion of the DC bus line 14 to which the bypass line 15 is connected. Furthermore, any reference in this description to the voltage of the electrical double-layer capacitors 601 indicates the voltage of one capacitor unit 60 (24 electrical double-layer capacitors 601 connected in series).

[0028] The four capacitor units 60 are connected to the DC bus line 14 via a connecting line 16. The connecting line 16 has a common line 161, which is connected to the DC bus line 14, and individual lines 162 that connect the capacitor units 60 and the common line 161.

[0029] The current sensors 61 are provided on the individual lines 162. The current sensors 61 measure the current flowing from each capacitor unit 60 to the DC bus line 14 at regular time intervals (such as 1 ms). 1-4-4. Short-circuit contactor

[0030] The short-circuit contactor 44 is located on the common line 161. When the short-circuit contactor 44 is switched on, the four capacitor units 60 and the DC bus line 14 are electrically connected, and current can be supplied to the four capacitor units 60. Likewise, when the short-circuit contactor 44 is switched off, the four capacitor units 60 and the DC bus line 14 are electrically disconnected, and the power supply from the four capacitor units 60 to the DC bus line 14 is stopped. 1-5. Control device

[0031] Fig. Figure 3 is a block diagram of the structure of the control device 10. The control device 10 has at least one detection unit 71, one storage unit 72, one tip detector 73, one calculation unit 74, one determination unit 75 and one stop execution unit 76.

[0032] The detection unit 71 detects current values ​​that are recorded by the four current sensors 61 at regular time intervals (for example, 1 ms).

[0033] The storage unit 72 stores the current value detected by the sensing unit 71. The storage unit 72 stores the current value for each capacitor unit 60 separately.

[0034] The peak detector 73 detects the peak of the current detected by each current sensor 61. For example, the peak detector 73 compares the current value detected by a current sensor 61 at that time with the last detected current value, and if the current value detected at that time is lower than the last detected current value, it detects that the current value reached its peak at the time the last detected current value was detected.

[0035] The calculation unit 74 calculates the average current value over a specific determination time centered on the point at which the last recorded current value was taken. Multiple determination times are set, and the average current value is calculated, for example, at 2 ms, 10 ms, 20 ms, 50 ms, and 100 ms.

[0036] The unit of determination 75 compares the average value of the current calculated for a determination period with a threshold value set for that determination period and determines whether the average value of the current is above the threshold value.

[0037] Fig. Figure 4 is a graph of the value of the maximum current that can be continuously supplied, in relation to the excitation time of a capacitor unit 60. Fig. For example, the maximum permissible current at 0.02 s is 1200 A. This indicates that if a current of 1200 A is supplied continuously for 0.02 s, this is the maximum current value that the capacitor unit 60 can tolerate. That is, using 1200 A as the threshold at 0.02 s, it is determined that the capacitor unit 60 will be damaged if a current exceeding 1200 A is supplied continuously for 0.02 s. The maximum permissible current at 0.05 s is 720 A. Therefore, it is determined that the capacitor unit 60 will be damaged if a current exceeding 720 A is supplied continuously for 0.05 s.

[0038] In this embodiment, an average value is used, and if the determination time is 0.02 seconds, it is determined that the capacitor unit 60 will be impaired if the average value exceeds 1200 A during this time. If the determination time were 0.05 seconds, it would be determined that the capacitor unit 60 will be impaired if the average value exceeds 720 A during this time.

[0039] Thus, the threshold for a determination time of 50 ms is set to a value lower than the threshold for a determination time of 20 ms, and the threshold for a longer determination time is set to a lower value.

[0040] If the determination unit 75 has determined that the average current value at a specific determination time exceeds the threshold value, the stop execution unit 76 switches off the short-circuit contactor 44 to stop the current flow in the connecting line 16. This stops the current supply from the four capacitor units 60 to the servo amplifier 22. 2. Operation

[0041] The operation of the press device 1 in an embodiment of the present invention will now be described, and an example of the method for controlling the press device of the present invention will also be described. Fig. 5A and Fig. 5B are flowcharts of the control of the press device 1 in this embodiment.

[0042] First, the control during the pressing process is described with reference to steps S10 to S22, and then the stop control for stopping the power supply from the capacitor units 60 is described with reference to steps S30 to S47.

[0043] First, in step S10, it is detected whether a press readiness signal is output by the control device 10. The press readiness signal is a signal that is output when the user presses a button while operating the press device 1, and it indicates that the press device 1 is ready for normal operation.

[0044] Next, in step S11, the electrical double-layer capacitors 601 are charged. Since the short-circuit contactor 43 is in its off state, no current flows to the bypass line 15, and the power output by the PWM converter 33 flows to the initial charging circuit 41. An electrical charge accumulates in the electrical double-layer capacitors 601, which are connected to the DC bus line 14, while current control is performed by the DC / DC converter 51 of the initial charging circuit 41. The DC / DC converter 51 monitors the voltage of the DC bus line 14. In step S12, charging continues until the voltage of the electrical double-layer capacitors 601 is raised to a predetermined level. The DC / DC converter 51 concludes that charging is complete when the input voltage and output voltage match and stops operation.

[0045] When, in step S12, it is detected that the voltage of the electrical double-layer capacitors 601 has been raised to the predetermined level by the DC / DC converter 51, the control device 10 connects the short-circuit contactor 43 in step S13. Consequently, the output signal of the PWM converter 33 bypasses the initial charging circuit 41 and is fed to the servo amplifier 22, and the charging and discharging of the electrical double-layer capacitors 601 begins in step S18.

[0046] When the short-circuit contactor 43 is connected in step S13, the control device 10 energizes the servo motor 21 in step S14.

[0047] Next, in step S15, the servomotor 21 is actuated according to the set movement to move the carriage 2 up and down. As the carriage 2 moves downwards, the servomotor 21 accelerates to a predetermined speed, after which it is driven at a constant speed. Together with the rotation of the crankshaft 25 generated by the drive of the servomotor 21, the carriage 2 rises after reaching bottom dead center. Then, the servomotor 21 is decelerated from a specific position to stop the carriage 2 at top dead center.

[0048] If a stop signal is issued for servomotor 21 in step S16, servomotor 21 is stopped in step S17. As a result, carriage 2 remains at its top dead center.

[0049] The change in energy consumption during pressing is described with reference to Fig. 6 described. Fig. Figure 6 is a graph of the energy change during pressing. A dotted line L1 and a solid line L2 are shown in Fig. Figure 6 shows the dotted line L1, which represents the change in energy consumption of press 1 over time during pressing. The solid line L2 represents the change in energy supplied by plant power supply 100 over time.

[0050] The downward movement of sled 2 begins in Fig. At time t1, servomotor 21 is accelerated from time t1 to t2 until it reaches a predetermined speed, and servomotor 21 consumes energy. As energy is consumed by servomotor 21 and the voltage of the DC bus line 14 decreases, a preset constant energy is supplied by servo power supply unit 5. As shown by the solid line L2, since only constant energy is supplied by servo power supply unit 5, any shortfall is supplied by the electrical double-layer capacitors 601. That is, any amount exceeding the solid line L2 in the dotted line L1 is supplied by the electrical double-layer capacitors 601.

[0051] When the speed of servomotor 21 reaches a predetermined speed at time t2, the servomotor 21 is driven at a constant speed from time t2 onwards. Since the load on servomotor 21 is low from time t2 until time t3, when the upper press die 7 comes into contact with the material (workpiece), the energy consumption indicated by the dotted line L1 is also low. At this point, the electrical double-layer capacitors 601 are charged with the electrical energy that exceeds the value of the dotted line L1 in the solid line L2.

[0052] Next, at time t3, the carriage 2 is lowered further, and pressing is performed on the workpiece until time t4. Energy consumption is highest at this time; however, as described above, a preset constant energy is supplied by the servo power supply unit 5, and any energy shortfall is supplied by the electrical double-layer capacitors 601.

[0053] When the carriage 2 reaches a predetermined position, the control device 10 decelerates the servo motor 21 to stop the carriage 2 at its top dead center. The time t5 in Fig. 6 indicates the delay start time of servomotor 21, and time t6 indicates the end of this delay. As in Fig. As shown in Figure 6, the output power is on the negative side from time t5 to t6, and regenerative energy is generated in the servomotor 21. This regenerative energy is used to charge the electrical double-layer capacitors 601.

[0054] On the other hand, during the pressing process of steps S14 to S17, the control of steps S18 to S22 is carried out in parallel. As described above, connecting the short-circuit contactor 43 in step S13 starts the charging and discharging of the electrical double-layer capacitors 601 in step S18.

[0055] In the next step, S19, the PWM converter 33 determines whether the voltage of the DC bus line 14 is at or above a predetermined level. If the voltage of the DC bus line 14 is at or above the predetermined level, the control process proceeds to step S20, and the energy is regenerated or recovered by the energy recovery function of the PWM converter 33 and fed back to the power supply 100. Since the voltage of the DC bus line 14 is equal to the voltage of the electrical double-layer capacitors 601, the PWM converter 33 detects the voltage of the electrical double-layer capacitors 601. That is, if the charge level of the electrical double-layer capacitors 601 is at or above a predetermined level, the regenerative energy generated by the servo motor 21 is sent to the power supply 100.If the voltage of the DC bus line 14 in step S19 is lower than the predetermined voltage, the electrical double-layer capacitors 601 are charged in step S21.

[0056] In the next step, S22, it is determined whether a press readiness signal is output by the control device 10. As long as a press readiness signal is detected, steps S18 to S21 are repeated. If, in addition, step S22 determines that the press readiness signal is not output by the control device 10, the control process terminates.

[0057] After the electrical double-layer capacitors 601 have been charged for the first time, they are charged by regenerative energy generated during the deceleration of the servomotor 21 or the like. For this reason, charging from the factory power supply 100 is not necessary.

[0058] As described above, since the rechargeable electrical double-layer capacitors 601 are provided, any energy deficiency is supplied by the electrical double-layer capacitors 601, so that, as in Fig. Figure 6 shows that the energy supplied by the plant's power supply can be kept constant.

[0059] The operation of steps S30 to S47, which is an example of stop control, is performed as in Fig. 5B is shown, performed in parallel with the operation of steps S10 to S22, which is an example of the press control described above.

[0060] In step S30, the acquisition unit 71 records current values, which are acquired by the four current sensors 61 at regular time intervals (e.g., 1 ms). The acquired current values ​​are stored in the storage unit 72.

[0061] In step S31, the peak detector 73 determines from the acquisition values ​​of each current detector 61 whether the current value at this acquisition time has fallen below the current value at the previous acquisition time. If it has fallen below this value, it is detected that a peak in the current value occurred at the previous acquisition time. The peak occurs, for example, in Fig. 6 at time t3.

[0062] Fig. Figure 7 is a graph of an example of the change in current value detected by a current sensor 61. The current value is assumed to be detected every 1 ms. For example, a comparison of the current value A1 detected at time t11 with the current value A2 detected at time t12 (t11 + 1 ms), which is the next detection time after t11, shows that the current value A2 is greater, so the determination in step S30 is repeated. Next, the peak detector 73 compares the current value A3 detected at time t13 (t12 + 1 ms) with the current value A2 detected at time t12, and since the current value A3 is greater than the current value A2, step S30 is repeated once more.

[0063] Next, the peak detector 73 compares the current value A4 (t13 + 1 ms) detected at time t14 with the current value A3 detected at time t13, and since the current value A4 detected at time t14 (this detection time) is smaller than the current value A3 detected at time t13 (the previous detection time), it is detected that the peak of the current value occurred at time t13.

[0064] Next, in step S32, the calculation unit 74 calculates the average current value at a time of 2 ms. The calculation unit 74 acquires data from the storage unit 72 about the current values ​​at 1 ms before and after time t13 (displayed in Fig. 7 by the determination time J2), which is the time of the current peak. In particular, the calculation unit 74 records current values ​​at times t12, t13 and t14. The calculation unit 74 then calculates the average value of the current for 2 ms, centered on time t13. That is, it calculates the average value of the current values ​​A2, A3 and A4 at times t12, t13 and t14, which are in Fig. The figures shown in 7 are calculated.

[0065] Next, in step S33, the determination unit 75 compares the threshold value stored in the storage unit 72, which was preset at a determination time of 2 ms, with the average current value calculated by the calculation unit 74. If the average current value is found to be above the threshold value, the controller proceeds to step S34. Here, the threshold value is set to the maximum permissible current value, which is defined in Fig. Figure 4 shows that the threshold at 2 ms is set to the maximum current value that will not damage capacitor unit 60 when capacitor unit 60 continuously supplies current for 2 ms. The same applies to the threshold at the following determination time of 10 ms, the threshold at the determination time of 20 ms, the threshold at the determination time of 50 ms, and the threshold at the determination time of 100 ms.

[0066] Then, in step S34, the stop execution unit 76 switches off the short-circuit contactor 44 and stops the power supply from the four capacitor units 60 to the servo amplifier 22.

[0067] If, on the other hand, step S33 determines that the average current value is at or below the threshold, the computation unit 74 calculates the average current value in step S35 over a determination time of 10 ms. The computation unit 74 acquires data from the storage unit 72 on the current values ​​5 ms before and after the peak time t13 (between times t5 and t6). Fig. In section 7, the determination time of 10 ms is designated as determination time J10. The calculation unit 74 then calculates the average value of the recorded current value data (11 data points for times t15 to t16).

[0068] Next, in step S36, the determination unit 75 compares the threshold value stored in the memory unit 72, which was set at a determination time of 10 ms, with the average current value calculated by the calculation unit 74. If it is determined that the average current value is above the threshold value, the controller proceeds to step S37, the short-circuit contactor 44 is switched off by the stop execution unit 76, and the current supply from the four capacitor units 60 to the servo amplifier 22 is stopped.

[0069] If, on the other hand, step S36 determines that the average current value is at or below the threshold, the computation unit 74 calculates the average current value at a determination time of 20 ms in step S38. The computation unit 74 acquires data on the current values ​​10 ms before and after the peak time t13 from the storage unit 72. The computation unit 74 then calculates the average of the acquired current value data.

[0070] Next, in step S39, the determination unit 75 compares the threshold value stored in the memory unit 72, which was set at a determination time of 20 ms, with the average current value calculated by the calculation unit 74. If it is determined that the average current value is above the threshold value, the controller proceeds to step S40, the short-circuit contactor 44 is switched off by the stop execution unit 76, and the current supply from the four capacitor units 60 to the servo amplifier 22 is stopped.

[0071] If, on the other hand, step S39 determines that the average current value is at or below the threshold, the computation unit 74 calculates the average current value at a determination time of 50 ms in step S41. The computation unit 74 acquires data from the storage unit 72 on the current values ​​25 ms before and after the peak time t13. The computation unit 74 then calculates the average of the acquired current value data.

[0072] Next, in step S42, the determination unit 75 compares the threshold value stored in the memory unit 72, which was set at a determination time of 50 ms, with the average current value calculated by the calculation unit 74. If it is determined that the average current value is above the threshold value, the controller proceeds to step S43, the short-circuit contactor 44 is switched off by the stop execution unit 76, and the current supply from the four capacitor units 60 to the servo amplifier 22 is stopped.

[0073] If, on the other hand, step S42 determines that the average current value is at or below the threshold, the computation unit 74 calculates the average current value at a determination time of 100 ms in step S44. The computation unit 74 acquires data from the storage unit 72 on the current values ​​50 ms before and after the peak time t13. The computation unit 74 then calculates the average of the acquired current value data.

[0074] Next, in step S45, the determination unit 75 compares the threshold value stored in the storage unit 72, which was set at a determination time of 100 ms, with the average value of the current calculated by the calculation unit 74. If it is determined that the average value of the current is above the threshold value, the controller proceeds to step S46, the short-circuit contactor 44 is switched off by the stop execution unit 76, and the current supply from the four capacitor units 60 to the servo amplifier 22 is stopped.

[0075] If, on the other hand, step S45 determines that the average current value is at or below the threshold, step S47 determines whether the press readiness signal is off or on, and if it is on, the control returns to step S30, and if a spike is detected next, the control of steps S32 to S46 is carried out.

[0076] On the other hand, if the read signal for the pressing process is switched off in step S47, the control ends.

[0077] When the peak current value is detected, it is determined whether the threshold value defined for each of several determination times centered on this peak value has been exceeded. If the threshold value has been exceeded, it is determined that there is a possibility of damage to the capacitor units 60, and the current supply from the four capacitor units 60 to the servo motor 21 is stopped. The operation of the press device 1 can also be stopped together with switching the short-circuit contactor 44 to its off state. 3. Features etc. (3-1)

[0078] The press device 1 in this embodiment comprises the carriage 2, the table 3, the servo motor 21, the capacitor units 60 (an example of energy storage units), the current sensors 61 (an example of current detectors), and the control device 10 (an example of a control unit). The upper press die 7 can be mounted on the carriage 2. The table 3 is arranged below the carriage 2, and the lower press die 8 can be placed on it. The servo motor 21 drives the carriage 2. The capacitor units 60 can supply stored energy to the servo motor 21. The current sensors 61 detect the current supplied by the capacitor units 60. The control device 10 performs a stop control to stop the current supply from the capacitor units 60 to the servo motor 21 based on the detected values ​​of the current sensors 61.

[0079] Consequently, if a large current flows from the capacitor units 60 in a short time and leads to damage to the capacitor units 60, the current supply from the capacitor units 60 to the servomotor 21 can be stopped. Therefore, the effect of a large current flowing in a short time on the electrical double-layer capacitors 601 can be minimized to reduce capacitance reduction and shorten service life, and the impairment of storage performance can be reduced. (3-2)

[0080] The pressing device 1 in this embodiment further comprises the short-circuit contactor 44 (an example of a switching unit). The short-circuit contactor 44 blocks the common line 161 (an example of a power line) from the capacitor units 60 to the servo motor 21. The control device 10 performs a stop control by actuating the short-circuit contactor 44.

[0081] Thus, the power supply from the capacitor units 60 to the servo motor 21 can be stopped. (3-3)

[0082] With the pressing device 1 in this embodiment, the control device 10 (an example of a control unit) performs a stop control when it is determined that the average value of the current supplied by the capacitor unit has exceeded a specific threshold value in a specific determination time.

[0083] Consequently, a large current in a short time, which could impair the storage performance of the electrical double-layer capacitors, can be detected before it flows, thus reducing the impairment of storage performance. (3-4)

[0084] With the pressing device 1 in this embodiment, the control device 10 (an example of a control unit) comprises the sensing unit 71, the peak detector 73, the calculation unit 74, the determination unit 75, and the stop execution unit 76. The sensing unit 71 acquires sensing values ​​from the current sensor 61 at specific time intervals. The peak detector 73 detects the peak of the current value based on the acquired values. The calculation unit 74 calculates the average value of the current at a determination time centered on the peak of the current value. The determination unit 75 compares the average value of the current calculated by the calculation unit 74 with a specific threshold value and determines whether the average value of the current is above the specific threshold value.The stop execution unit 76 performs a stop control when the determination unit 75 has determined that the average value of the current is above the specific threshold.

[0085] Consequently, the average value of the current within a period that includes time t13, at which the current value reaches its peak, can be calculated, so that it can be determined whether or not a stop control should be carried out within a period in which there is a high probability that a large amount of current will flow in a short time. (3-5)

[0086] The pressing device 1 in this embodiment provides several measurement times of different durations (for example, 2 ms, 5 ms, 10 ms, 20 ms, 50 ms, and 100 ms). A specific threshold value is provided for each measurement time. The longer a measurement time, the lower the corresponding set threshold value.

[0087] Since the current value, which affects the lifetime impairment and the like of the 601 electric double-layer capacitors, varies with the excitation time, several determination times are set, and for each time a threshold value is set, which improves the performance when detecting a large current that affects the 601 electric double-layer capacitors. (3-6)

[0088] In this embodiment of the press 1, several capacitor units 60 are provided. A current sensor 61 (an example of a current detector) is provided for each of the capacitor units 60. A stop control is performed to stop the current supply from all capacitor units 60 to the servo motor 21. The control device 10 (an example of a control unit) executes a stop control when it has been determined that the average value of the current supplied by at least one capacitor unit 60 exceeds a specific threshold value.

[0089] Consequently, in a configuration where several capacitor units 60 are provided, it is possible to detect the flow of a large current in a short time, which would adversely affect the electrical double-layer capacitors 601. (3-7)

[0090] In the pressing device 1 in this embodiment, each capacitor unit 60 (an example of an energy storage unit) has several electrical double-layer capacitors 601 (an example of a storage device). This allows a large amount of energy to be stored. (3-8)

[0091] The method for controlling the press of this embodiment comprises step S31 (an example of a sensing step) and steps S33, S36, S39, S42, S45, S34, S37, S40, S43, and S46 (an example of a stop step). Step S31 (an example of a sensing step) involves sensing the current supplied by the capacitor units 60 to the servo motor 21, which drives the carriage 2. Steps S33, S36, S39, S42, S45, S34, S37, S40, S43, and S46 (an example of a stop step) involve stopping the current supply from the capacitor units 60 to the servo motor 21 based on the value sensed in step S31 (an example of a sensing step).

[0092] Consequently, if a large current flows from the capacitor units 60 in a short time and leads to damage to the capacitor units 60, the current supply from the capacitor units 60 to the servomotor 21 can be stopped. Therefore, it is possible to suppress the effect that the flow of a large current in a short time would have on the electrical double-layer capacitors 601, and to reduce the reduction in capacitance and the impairment of their service life, thereby reducing the impairment of storage performance. 4. Other embodiments

[0093] One embodiment of the present invention has been described above, but the present invention is not limited to or by the above embodiment, and various modifications are possible. (A) In the foregoing embodiment, five different determination times (2 ms, 10 ms, 20 ms, 50 ms and 100 ms) are provided, but five is not the only option, and there can only be one. (B) In the above embodiment, the current supply to the four capacitor units 60 is stopped by switching off the short-circuit contactor 44, but the current supply to the capacitor units 60 can be stopped by stopping the servo motor 21. In this case, a short-circuit contactor 44 must be provided, and the stop execution unit 76 sends a stop command to the servo amplifier 22. Since this stops the drive of the servomotor 21, the power supply from the capacitor units 60 to the servomotor 21 can also be stopped. (C) In the foregoing embodiment, the determination is carried out using the average value of the current values, but the determination can instead be carried out using the integrated value of the current. (D) In ​​the foregoing embodiment, the peak of the current value is detected and the cessation of the current supply from the capacitor units 60 is determined at a time centered on this peak, but this is not the only option. For example, the determination can be carried out using data that count back 2 ms, 10 ms, 20 ms, 50 ms and 100 ms from each point at which the data are detected. (E) In the foregoing embodiment, four capacitor units 60 are provided in which 24 electrical double-layer capacitors 601 are connected in series, and these four capacitor units 60 are connected in parallel, but the number and connection configuration are not limited to these. (F) In the foregoing embodiment, the electrical double-layer capacitors 601 are used as an example of an energy storage device, but electrical double-layer capacitors are not the only option, and aluminum electrolytic capacitors or the like may be used instead. In other words, the energy storage device may be of any type capable of storing an electrical charge. In addition, an energy storage unit, of which the capacitor units 60 are an example, may be provided with several such energy storage devices. INDUSTRIAL APPLICABILITY

[0094] The pressing device and the method for controlling the pressing device of the present invention have the effect of enabling a reduction in the impairment of storage performance and are useful, for example, in a factory production line.

Claims

[1] Pressing device (1) comprising: a slide (2) which is set up to mount an upper press mold (7) on it; a table (3) arranged under the carriage (2), the table (3) being configured to place a lower press mold (8) on it; a servomotor (21) which is set up to drive the carriage (2); an energy storage unit (60) configured to supply stored energy to the servomotor (21); and a current detector (61) which is configured to detect current supplied by the energy storage unit (60); characterized by a control unit (10) which is configured to perform a stop control in order to stop the current supply from the energy storage unit (60) to the servomotor (21) based on a detection value of the current detector (61) when it is determined that an average value of the current supplied by the energy storage unit (60) within a specific determination time has exceeded a specific threshold value. [2] Pressing device (1) according to claim 1, further comprising a shutdown unit (44) which is configured to shut off a power line from the energy storage unit (60) to the servo motor (21), wherein the control unit (10) is configured to perform the stop control by actuating the shutdown unit (44). [3] Pressing device (1) according to claim 1, further comprising a servo amplifier (22) which is configured to control the servo motor (21), wherein the control unit (10) performs the stop control by issuing a servo motor stop instruction to the servo amplifier (22). [4] Pressing device (1) according to one of claims 1 to 3, wherein the control unit (10) includes: a detection unit (71) which is set up to detect the detection value of the current detector (61) at specific time intervals; a peak detector (73) configured to detect a peak of a current value based on the detection value; a calculation unit (74) which is set up to calculate the average value of the current during the determination period around the peak of the current value; a determination unit (75) set up to compare the average value of the current calculated by the calculation unit (74) with the specific threshold and to determine whether the average value of the current is above the specific threshold; and a stop execution unit (76) which is configured to perform the stop control when the determination unit (75) determines that the average value of the current is above the specific threshold. [5] Pressing device (1) according to any one of claims 1 to 4, where several determination times of different durations are provided, the specific threshold value is provided in connection with each of the determination times, and The longer the determination time, the lower the corresponding set specific threshold value. [6] Pressing device (1) according to any one of claims 1 to 5, including several energy storage units (60), the current detector (61) is provided for each of the energy storage units (60), The stop control serves to stop the power supply from all energy storage units (60) to the servo motor (21), the control unit (10) executes the stop control when it has been determined that the average value of the current supplied by at least one of the electrical energy storage units (60) is above the specific threshold. [7] Pressing device (1) according to any one of claims 1 to 6, wherein the energy storage unit (60) contains several storage devices, and the storage devices are electrical double-layer capacitors (601). [8] Method for controlling a press device (1), comprising: a detection step for detecting current supplied by an energy storage unit (60) to a servo motor (21) configured to drive a carriage; and characterized by a stop step to stop the power supply from the energy storage unit (60) to the servo motor (21) based on a detection value in the detection step when it is determined that an average value of the current supplied by the energy storage unit (60) within a specific determination time has exceeded a specific threshold value.

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