Control device

Abstract

To provide a control device capable of stably controlling a flow rate of a vacuum device, even if a set vacuum pressure is set to be low so as to further thicken film thickness of an oil film layer of workpiece.SOLUTION: A control device 30 receives component information transmitted from a central management device 7, PIC-controls frequencies of motors of two vacuum pumps provided on a vacuum device 50 by an inverter, thereby converges a suction pressure of the vacuum device 50 connected to suction rolls 15a and 15b for sucking an oil content formed on a surface and a rear face of workpiece W sent to a press working device 3 to a set vacuum pressure specified by the component information, and controls the film thickness of the oil film layer formed on the surface and the rear face. PLC of the control device 30 switches the number of the vacuum pumps to be driven among the two vacuum pumps according to the set vacuum pressure included in the component information transmitted from the central management device 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device. [Background technology]

[0002] Conventionally, a film thickness control device has been known that divides a chamber installed on a transport path that sends the workpiece to a processing device into a front chamber in which a pinch roll that performs the workpiece transport operation is arranged on the upstream side of the transport path, a cleaning chamber in which a brush roll that rotates in contact with the front and back surfaces of the workpiece while cleaning oil is supplied to the front and back surfaces of the workpiece is arranged on the downstream side of the transport path adjacent to the front chamber, and a rear chamber in which an oil cut roll that wipes off the oil from the front and back surfaces of the workpiece by contact with the roll circumferential surface and a suction roll that sucks up the oil from the front and back surfaces of the workpiece are arranged on the downstream side of the transport path adjacent to the cleaning chamber, and that controls the film thickness of the oil film to be formed on the workpiece after cleaning within a predetermined range (see, for example, Patent Document 1).

[0003] This device is equipped with a vacuum device that converges the suction pressure of a vacuum pump connected to a suction roll to a set vacuum pressure by PID-controlling the motor frequency with an inverter, and a setting table that stores the correspondence between the desired oil film thickness to be formed on the cleaned workpiece, the set pressure of the vacuum pump, and the appropriate frequency range of the motor.The set vacuum pressure and appropriate frequency range of the vacuum pump are set in a control condition storage area based on the desired film thickness set by the film thickness setting means and the stored contents of the setting table, and the equipment is operated based on the settings in the control condition storage area.

[0004] Increasing the vacuum pressure setting of the vacuum pump will result in a thinner oil film layer formed on the front and back surfaces of the workpiece. Conversely, lowering the vacuum pressure setting will result in a thicker oil film layer formed on the front and back surfaces of the workpiece. The amount of deformation of a workpiece due to press working varies depending on the part being pressed. Generally, the greater the deformation of a workpiece due to press working, the thicker the oil film layer formed on the front and back surfaces of the workpiece must be. For example, parts such as automobile side outers are subject to greater deformation due to press working than other parts. In this case, in order to thicken the film thickness, it is necessary to set the vacuum pressure lower than when manufacturing other parts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6340603 Summary of the Invention [Problem to be solved by the invention]

[0006] To lower the set vacuum pressure, it is necessary to lower the suction pressure of the vacuum pump. The suction pressure of a vacuum pump can be adjusted by PID control of the motor frequency using an inverter. However, if the frequency becomes too low and the motor rotation speed becomes too low, the flow control of the vacuum pump becomes unstable. For example, if the motor rotation speed is so low that it can be seen with the naked eye, or if it is so low that it causes hunting (jerky movement), the flow control becomes unstable. Therefore, in order to handle workpieces with greater deformation, there was a need to develop a control device that could provide stable flow control of the vacuum device even when the set vacuum pressure was low.

[0007] An object of the present invention is to provide a control device that can stably control the flow rate of a vacuum device even when the set vacuum pressure is lowered in order to increase the thickness of the oil film on the workpiece. [Means for solving the problem]

[0008] The control device of claim 1 receives part information transmitted from an external device, and controls the suction pressure of a vacuum device connected to a suction roll that sucks oil formed on the front and back surfaces of a workpiece to be sent to a press processing device by PID control of the frequency of a vacuum pump motor provided in the vacuum device using an inverter, thereby converging the suction pressure to a set vacuum pressure designated by the part information and controlling the thickness of an oil film layer formed on the front and back surfaces, and the vacuum device , a first vacuum pump and a second vacuum pump having the same suction capacity and a vacuum pressure setting unit configured to set the vacuum pressure. The first vacuum pump and the second vacuum pump A drive control unit is provided to switch the number of vacuum pumps to be driven. When the set vacuum pressure is equal to or higher than a threshold value, the drive control unit drives both the first vacuum pump and the second vacuum pump simultaneously at the same suction pressure, and PID controls the frequencies of the motors of the first vacuum pump and the second vacuum pump so that the combined suction pressure becomes the set vacuum pressure. When the set vacuum pressure is lower than the threshold value, the drive control unit drives only one of the first vacuum pump and the second vacuum pump, and PID controls the frequency of the motor of the other vacuum pump so that the suction pressure of the other vacuum pump becomes the set vacuum pressure. The control device can automatically switch the number of vacuum pumps to be driven depending on the set vacuum pressure, so the inverter can maintain stable motor rotation even at low set vacuum pressures. This allows the control device to operate the vacuum device stably, so the thickness of the oil film layer can be stably controlled. In addition, by not driving some of the multiple vacuum pumps, the suction capacity of the driven vacuum pumps can be maximized. Furthermore, when the set vacuum pressure is equal to or higher than a threshold, the control device drives two vacuum pumps with equivalent suction capacities simultaneously at the same suction pressure, thereby facilitating control of the first and second vacuum pumps. Furthermore, when the set vacuum pressure is below the threshold, only one vacuum pump is driven, enabling stable control even at a low set vacuum pressure. Furthermore, when only one vacuum pump is driven, the other is stopped, allowing the suction capacity of the driven pump to be maximized.

[0009]

[0010]

[0011]

[0012] Claim 2 Control device is a control device that receives component information transmitted from an external device, and adjusts the suction pressure of a vacuum device connected to a suction roll that sucks oil formed on the front and back surfaces of a workpiece to be sent to a press processing device by PID control of the frequency of a vacuum pump motor provided in the vacuum device using an inverter, thereby converging the suction pressure to a set vacuum pressure designated by the component information and controlling the thickness of an oil film layer formed on the front and back surfaces, and the vacuum device is equipped with a first vacuum pump and a second vacuum pump having a lower suction capacity than the first vacuum pump, and a control device that drives either the first vacuum pump or the second vacuum pump according to the set vacuum pressure. The system includes a drive control unit that switches the number of vacuum pumps. When the set vacuum pressure is equal to or higher than a threshold, the drive control unit drives both the first vacuum pump and the second vacuum pump, and PID-controls the motor frequencies of the first vacuum pump and the second vacuum pump so that the combined suction pressure of the first and second vacuum pumps becomes the set vacuum pressure. When the set vacuum pressure is less than the threshold, the drive control unit drives only the second vacuum pump, and PID-controls the motor frequency of the second vacuum pump so that the suction pressure of the second vacuum pump becomes the set vacuum pressure. The control device can automatically switch the number of vacuum pumps to be driven depending on the set vacuum pressure, allowing the inverter to maintain stable motor rotation even at low set vacuum pressures. This allows the control device to operate the vacuum device stably, thereby stably controlling the thickness of the oil film layer. Furthermore, by deactivating some of the multiple vacuum pumps, the suction capacity of the activated vacuum pumps can be maximized. If the set vacuum pressure is below the threshold, the second vacuum pump, which has a lower suction capacity than the first vacuum pump, only This allows the inverter to maintain stable motor rotation even at low set vacuum pressures.

[0013] Claim 3The control device may include a reception unit that receives a change to the set vacuum pressure, and the drive control unit may include a post-change drive control unit that, when the reception unit receives a change to the set vacuum pressure, again switches the number of vacuum pumps to be driven in accordance with the changed set vacuum pressure. When it is desired to fine-tune the set vacuum pressure by checking the condition of the suction roll or the condition of the front and back surfaces of the workpiece, the reception unit can receive a change to the set vacuum pressure. Then, since the number of vacuum pumps to be driven can be switched again in accordance with the changed set vacuum pressure, it is possible to constantly drive the number of vacuum pumps corresponding to the set vacuum pressure. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a configuration diagram of a press working system 1. [Figure 2] FIG. 2 is a front view of the film thickness control device 10. [Figure 3] FIG. 2 is a plan view of the film thickness control device 10. [Figure 4] FIG. 2 is a front view of suction rolls 15a and 15b, a vacuum device 50, and a control device 30. [Figure 5] 10 is a table showing the relationship between film thickness and set vacuum pressure. [Figure 6] FIG. 2 is a front view of the operation panel 110. [Figure 7] FIG. 2 is a block diagram showing a control system in a control device 30. [Figure 8] 10 is a flowchart of a vacuum pump control process. [Figure 9] 1 is a front view of suction rolls 15a and 15b, a vacuum device 150 (modified example), and a control device 130. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described. The configurations, control processes, etc. described below are merely illustrative examples and are not intended to be limiting unless otherwise specified. The drawings are used to explain technical features that can be adopted by the present invention.

[0016] The configuration of press working system 1 will be described with reference to Figure 1. Press working system 1 is a system that manufactures automobile parts P1 to P4 by cleaning a workpiece, which is sheet metal, and forming an oil film layer of a predetermined thickness on the surface of the workpiece, and then press working the workpiece. For example, part P1 is a side outer, part P2 is a front door, part P3 is a trunk lid, and part P4 is a hood. Press working system 1 includes a central management unit 7, a work supply device 2, a film thickness control device 10, a press working device 3, a die changer 5, a control device 30, and a vacuum device 50.

[0017] The central management unit 7 controls the operation of the press working system 1. The central management unit 7 transmits part information to each of the work supply device 2, the press working device 3, the die changer 5, and the control device 30. The work supply device 2, the press working device 3, the die changer 5, and the control device 30 operate based on the part information received from the central management unit 7.

[0018] The work supply device 2 includes, for example, four stockers A to D. Stocker A stocks multiple workpieces W1. Workpiece W1 is a workpiece for part P1. Workpiece W1 is assigned part number = 001. Stocker B stocks multiple workpieces W2. Workpiece W2 is a workpiece for part P2. Workpiece W2 is assigned part number = 002. Stocker C stocks multiple workpieces W3. Workpiece W3 is a workpiece for part P3. Workpiece W3 is assigned part number = 003. Stocker D stocks multiple workpieces W4. Workpiece W4 is a workpiece for part P4. Workpiece W4 is assigned part number = 004. In the following description, workpieces W1 to W4 will be collectively referred to as "workpiece W." Note that the front and back surfaces of the workpieces W stored in stockers A to D before cleaning have already been subjected to surface treatment such as rust prevention.

[0019] The part information sent by the central control unit 7 to the work supply device 2 includes a part number. The work supply device 2 transports the work W corresponding to the part number sent from the central control unit 7 from a stocker and supplies it to the entrance of the transfer line 6. The transfer line 6 is a line that transfers the work from the work supply device 2 to the press processing device 3. The transfer line 6 is provided with an automatic transfer mechanism such as a conveyor.

[0020] The film thickness control device 10 is installed midway along the transfer line 6. The film thickness control device 10 cleans the workpiece W transferred along the transfer line 6 and forms an oil film layer of a predetermined thickness on the top and bottom surfaces of the workpiece W. The predetermined thickness of the oil film layer to be formed on the top and bottom surfaces of the workpiece W is determined for each automobile part. A vacuum device 50 is attached to the film thickness control device 10. The vacuum device 50 is connected to suction rolls 15a and 15b of the film thickness control device 10, which will be described later. Under the control of the control device 30, the vacuum device 50 sucks the oil film layer formed on the top and bottom surfaces of the workpiece W from the suction rolls 15a and 15b, adjusting the film thickness to a predetermined value. The specific configuration of the film thickness control device 10 will be described later.

[0021] The control device 30 controls the operations of the film thickness control device 10 and the vacuum device 50 based on the component information transmitted from the central control device 7. The component information transmitted from the central control device 7 to the film thickness control device 10 and the vacuum device 50 includes various information such as oil shower conditions and set vacuum pressure, which will be described later.

[0022] The press working device 3 presses the workpiece W, which has oil film layers of a predetermined thickness formed on its upper and lower surfaces, to form automobile parts, based on the part information sent from the central management device 7. The part information sent from the central management device 7 to the press working device 3 includes press conditions. The press conditions are, for example, the pressure required for punching or bending by pressing. The press conditions differ for each automobile part. A die is fixed to the press working device 3. The die is replaced for each automobile part by a die changer 5.

[0023] The die changer 5 is attached to the press processing device 3. The die changer 5 changes and replaces the dies fixed to the press processing device 3 based on part information transmitted from the central management device 7. The part information transmitted from the central management device 7 to the die changer 5 includes die identification information. The die changer 5 holds four dies K1 to K4, and changes and replaces them for the press processing device 3 based on the die identification information transmitted from the central management device 7.

[0024] The die K1 is a die that presses the workpiece W1 to form the part P1. The die K2 is a die that presses the workpiece W2 to form the part P2. The die K3 is a die that presses the workpiece W3 to form the part P3. The die K4 is a die that presses the workpiece W4 to form the part P4.

[0025] 2 and 3, the specific configuration of the film thickness control device 10 will be described. The film thickness control device 10 accommodates, in order from the upstream side, a pair of upper and lower pinch rolls 12a, 12b, a pair of upper and lower brush rolls 13a, 13b, a pair of upper and lower oil cut rolls 14a, 14b, and a pair of upper and lower suction rolls 15a, 15b within a chamber 11.

[0026] The chamber 11 is divided into four compartments by three sets of shielding plates 16a, 16b, 17a, 17b, 18a, 18b: anterior chamber 11A, cleaning chamber 11B, wiping chamber 11C, and suction chamber 11D. The ante-chamber 11A houses pinch rolls 12a and 12b. The cleaning chamber 11B houses brush rolls 13a and 13b. The wiping chamber 11C houses oil-cutting rolls 14a and 14b. The suction chamber 11D houses suction rolls 15a and 15b.

[0027] In the cleaning chamber 11B, cleaning oil spray nozzles 19a to 19d are installed along the entire length of the brush rolls 13a and 13b near the lower ends of the upper shielding plates 16a and 17a and near the upper ends of the lower shielding plates 16b and 17b. In the suction chamber 11D, an oil spray pipe 21 is installed along the entire length of the upper suction roll 15a near the upper end of the upper shielding plate 18a.

[0028] The workpiece W entering through the entrance 11in of the chamber 11 is pinched from above and below by pinch rolls 12a and 12b installed in the front chamber 11A and transported toward the exit 11out. In the cleaning chamber 11B, cleaning oil is sprayed onto the upper and lower surfaces of the entering workpiece W by cleaning oil spray nozzles 19a to 19d and brushed by brush rolls 13a and 13b, thereby performing brush cleaning.

[0029] In the wiping chamber 11C, oil is wiped off by oil cut-off rolls 14a and 14b. The oil cut-off rolls 14a and 14b rotate in contact with the upper and lower surfaces of the incoming workpiece W. In the suction chamber 11D, oil is sucked by suction rolls 15a and 15b. The suction rolls 15a and 15b rotate in contact with the upper and lower surfaces of the incoming workpiece W. In this way, the workpiece W supplied from the work supply device 2 has its upper and lower surfaces cleaned, wiped, and sucked while being transported through the chamber 11 of the film thickness control device 10 from the entrance 11in to the exit 11out, and is then fed into the press working device 3.

[0030] As shown in Fig. 4, nonwoven fabric laminates 22a and 22b are attached to the outer periphery of hollow suction rolls 15a and 15b. A linear pressure applying mechanism (not shown) is provided on the upper suction roll 15a. The linear pressure applying mechanism applies a roll pressing pressure toward the lower suction roll 15b.

[0031] Before starting continuous cleaning of the workpieces W, an oil shower process is performed. The oil shower process is a process in which the upper and lower suction rolls 15a, 15b are brought into contact with each other by a linear pressure applying mechanism, oil is sprayed from the oil spray pipe 21 for a predetermined time, and then the suction rolls 15a, 15b are idled for a predetermined time based on oil shower conditions that vary depending on the type of workpiece W. The oil shower conditions include the amount of oil to be sprayed and the idle rotation time. The oil shower conditions are specified by component information sent from the central management unit 7 to the control device 30. By performing the oil shower process, the nonwoven fabric laminates 22a, 22b of the suction rolls 15a, 15b, respectively, are brought into a desired wet state.

[0032] As shown in FIG. 4, a vacuum device 50 is connected to the suction rolls 15a and 15b via rotary joints 15e and 15f. The vacuum device 50 includes two vacuum pumps 51 and 52, a pressure switch (not shown), etc., and its operation is controlled by a control device 30. The vacuum pumps 51 and 52 have the same suction capacity. The vacuum pumps 51 and 52 are PID-controlled by an inverter motor so as to be driven simultaneously by the control device 30 described later and maintain the set vacuum pressure at the same suction pressure.

[0033] Referring to FIG. 5, the relationship between the film thickness of the oil film layer and the set vacuum pressure will be described. The table shown in FIG. 5 shows the relationship between the film thickness of the oil film layer formed on the upper surface of the work W and the set vacuum pressure. To control the film thickness to M1 (g / m

[0035] , , , ), the set vacuum pressure of the vacuum device 50 is set to S1 (-Kpa). To control the film thickness to M2 (g / m 2 ), the set vacuum pressure of the vacuum device 50 is set to S2 (-Kpa). To control the film thickness to M3 (g / m 2 ), the set vacuum pressure of the vacuum device 50 is set to S3 (-Kpa). To control the film thickness to M4 (g / m 2 ), the set vacuum pressure of the vacuum device 50 is set to S4 (-Kpa). The film thickness has the relationship of M1 < M2 < M3 < M4, and the set vacuum pressure has the relationship of S1 > S2 > S3 > S4.

[0034] That is, to reduce the film thickness, the set vacuum pressure can be set higher, and to increase the film thickness, the set vacuum pressure can be set lower. In this embodiment, the film thickness of the oil film layer formed on each of the upper and lower surfaces of the works W1 to W4 is determined according to the corresponding automobile parts P1 to P4. Therefore, the central management device 7 stores the set vacuum pressure for each of the works W1 to W4. The central management device 7 transmits the set vacuum pressure to the control device 30 as part information according to the type of the work W conveyed along the conveyance line 6.

[0035] The set vacuum pressure can be adjusted using an operation panel 110 (see FIG. 3). The operation panel 110 is provided on the control device 30. The operation panel 110 is a touch panel that accepts various operations and displays various information. Adjustment of the set vacuum pressure using the operation panel 110 (see FIG. 3) will be described later.

[0036] As shown in FIG. 5, the operation panel 110 is provided with a set vacuum pressure digital display 111a, an actual pressure digital display 111b, an actual pressure analog display 111c, a digital display 112a and analog display 112b for the inverter frequency, a set vacuum pressure up switch 114a for adjusting the set vacuum pressure, and a set vacuum pressure down switch 114b.

[0037] The control system in the control device 30 will be described with reference to Fig. 6. The control device 30 includes a PLC 31 and a memory unit 32. The memory unit 32 stores various information such as a setting table (not shown). The setting table stores a set vacuum pressure in association with an inverter frequency range. The control device 30 is electrically connected to an operation panel 110, a film thickness control device 10, and a vacuum device 50. The PLC 31 receives input from various switches 114a, 114b, and 115 displayed on the operation panel 110, and displays various information on various display units 111a to 111c, 112a, and 112b.

[0038] For example, when the control device 30 receives part information from the central management device 7, the PLC 31 sprays oil from the oil spray pipe 21 of the film thickness control device 10 and runs the suction rolls 15a and 15b idly, based on the oil shower execution conditions included in the part information.

[0039] Furthermore, the PLC 31 displays the new set air pressure included in the part information on the set vacuum pressure digital display 111a. Furthermore, the PLC 31 causes the suction pressure of the vacuum device 50 to converge to the new set air pressure by PID controlling the frequency of the motor using an inverter.

[0040] The set vacuum pressure can be adjusted on the operation panel 110. It can be increased by pressing the set vacuum pressure up switch 114a, and decreased by pressing the set vacuum pressure down switch 114b. The PLC 31 digitally displays the set vacuum pressure on the set vacuum pressure digital display 111a in accordance with the result of the set vacuum pressure adjustment, and updates the set vacuum pressure.

[0041] The vacuum device 50 constantly transmits the actual suction pressure and inverter frequency (hereinafter referred to as INV frequency) during operation to the control device 30. The PLC 31 digitally displays the actual suction pressure during operation on the actual pressure digital display unit 111b and displays it as a scale on the actual pressure analog display unit 111c. Furthermore, the PLC 31 digitally displays the INV frequency during operation on the INV frequency digital display unit 112a and displays it as a scale on the INV frequency analog display unit 112b. Furthermore, the PLC 31 displays indicator scales 112c and 112d on the INV frequency analog display unit 112b, which correspond to the inverter frequency range stored in a setting table (not shown) stored in the memory unit 32. By visually checking the indicator scales 112c and 112d, the operator can intuitively confirm whether the fluctuation state of the INV frequency during operation is within an appropriate range.

[0042] An example of the operation of the press working system 1 will be described with reference to Figure 1. For example, the case of press working part P1 (side outer) will be described as an example. In this case, the central management unit 7 sends part information of part number = 001 to the work supply device 2, sends part information including the oil shower conditions and set new air pressure corresponding to the work W1 to the control device 30, sends part information including identification information for identifying the die K1 to the die changer 5, and sends part information including the press conditions for the work W1 to the press working device 3.

[0043] The work supply device 2 transports the work W1 from the stocker A and supplies it to the transfer line 6 based on the part information for part number = 001 received from the central control device 7. The work W1 supplied to the transfer line 6 is transferred to the film thickness control device 10. The control device 30 controls the operation of the film thickness control device 10 based on the oil shower conditions received from the central control device 7. In parallel with this, the control device 30 controls the operation of the vacuum device 50 so that the suction pressure of the vacuum device 50 becomes the set vacuum pressure received from the central control device 7. The control operation of the vacuum device 50 by the PLC 31 of the control device 30 will be described later. The work W on which an oil film layer of a predetermined thickness has been formed by the film thickness control device 10 is transferred to the press working device 3 via the transfer line 6.

[0044] The die changer 5 sets the die K1 in the press working device 3 based on the die identification information received from the central control device 7. The press working device 3 performs press working on the workpiece W1 based on the press conditions received from the central control device 7. In this way, the press working device 3 produces a part P1. The produced part P1 is transported to the automobile assembly line and painted in a predetermined color.

[0045] The vacuum pump control process will be described with reference to Fig. 7. When the PLC 31 receives the set vacuum pressure as part information from the central control unit 7, the PLC 31 executes this process.

[0046] The PLC 31 determines whether the received set vacuum pressure is equal to or greater than a threshold value a1 (S11). The threshold value a1 is a reference value for determining whether to drive both of the two vacuum pumps 51, 52 or only one of them depending on the set vacuum pressure. The threshold value a1 can be changed as appropriate by the operator.

[0047] The PLC 31 uses two vacuum pumps 51, 52 with the same suction capacity, and automatically switches the number of vacuum pumps to be driven between two or one depending on whether the set vacuum pressure is above or below a1 (-KPa). When driving two vacuum pumps 51, 52, the PLC 31 drives the two pumps simultaneously at the same suction pressure, and uses an inverter to PID control the motor frequency so that the combined suction pressure becomes the set vacuum pressure.

[0048] If the set vacuum pressure is equal to or greater than the threshold a1 (S11: YES), the PLC 31 simultaneously drives the two vacuum pumps 51 and 52, and uses the inverter to PID-control the motor frequency so that the suction pressures of each converge to the set vacuum pressure (S12). Because the PLC 31 drives the two vacuum pumps 51 and 52, it can stably maintain a high set vacuum pressure equal to or greater than the threshold a1. This allows the PLC 31 to accurately and stably control the thickness of the oil film layer.

[0049] On the other hand, if the set vacuum pressure is less than the threshold a1 (S11: NO), the PLC 31 drives only one of the vacuum pumps 51, and uses the inverter to PID control the motor frequency so that the suction pressure of only one pump converges to the set vacuum pressure (S13). Because the PLC 31 drives only one vacuum pump 51, the motor can rotate stably even at a low set vacuum pressure less than the threshold a1. This allows the PLC 31 to stably maintain a low set vacuum pressure less than the threshold a1, thereby enabling accurate and stable control of the oil film thickness.

[0050] Next, the PLC 31 determines whether the set vacuum pressure up switch 114a on the operation panel 110 has been pressed by the operator (S14). If the set vacuum pressure up switch 114a has been pressed (S14: YES), the PLC 31 updates the current set vacuum pressure to a value (set vacuum pressure - α) that is increased by a predetermined amount (S16).

[0051] If the set vacuum pressure up switch 114a has not been pressed (S14: NO), the PLC 31 determines whether the set vacuum pressure down switch 114b has been pressed by the operator (S15). If the set vacuum pressure down switch 114b has been pressed (S15: YES), the PLC 31 updates the current set vacuum pressure to a value (set vacuum pressure + α) that is a predetermined amount lower (S17).

[0052] If neither the set vacuum pressure up switch 114 nor the set vacuum pressure down switch 114b is pressed (S14: NO, S15: NO), the PLC 31 advances the process to S21, which will be described later.

[0053] When the set vacuum pressure is updated (S16, S17), the PLC 31 again determines whether the updated set vacuum pressure is equal to or greater than the threshold value a1 (S18). If the updated set vacuum pressure is equal to or greater than the threshold value a1 (S18: YES), the PLC 31 simultaneously drives the two vacuum pumps 51 and 52, and performs PID control of the motor frequency using the inverter so that the suction pressures of the two pumps converge to the set vacuum pressure (S19).

[0054] On the other hand, if the updated set vacuum pressure is less than threshold value a1 (S18: NO), PLC 31 drives only one of the vacuum pumps 51 and uses the inverter to PID control the motor frequency so that the suction pressure of only one pump converges to the set vacuum pressure (S20).

[0055] Next, the PLC 31 determines whether or not new part information has been received from the central management device 7 (S21). If no part information has been received (S21: NO), the PLC 31 returns to S14 and repeats the above process. If new part information has been received (S21: YES), the PLC 31 returns to S11 and repeats the above process.

[0056] Meanwhile, during continuous operation by the press working system 1, when the inverter frequency on the analog display unit 112b on the operation panel 110 shown in Fig. 6 falls below the lower limit indicator scale 112c, it means that the surface of the cleaned workpiece W is "too wet," and conversely, when the inverter frequency on the analog display unit 112b exceeds the upper limit indicator scale 112d, it means that the surface of the cleaned workpiece W is "too dry." In other words, the operator can easily confirm whether the predetermined film thickness has been achieved by checking whether the scale display for the INV frequency analog display unit 112b is within the range of the indicator scales 112c and 112d.

[0057] If the surface is "too wet," the operator can easily adjust the vacuum pressure by pressing the set vacuum pressure up switch 114a to increase the set vacuum pressure and increase the amount of oil suctioned by the suction rolls 15a and 15b. Conversely, if the surface is "too dry," the operator can easily adjust the vacuum pressure by pressing the set vacuum pressure down switch 114b to decrease the set vacuum pressure and decrease the amount of oil suctioned by the suction rolls 15a and 15b.

[0058] In the above description, the central management unit 7 is an example of an "external device" of the present invention. The vacuum pump 51 is an example of a "first vacuum pump" of the present invention, and the vacuum pump 52 is an example of a "second vacuum pump" of the present invention. The PLC 31 that executes S11 to S13 in FIG. 8 is an example of a "drive control unit" of the present invention. The PLC 31 that executes S18 to S20 is an example of a "post-change drive control unit" of the present invention. The operation panel 110 is an example of a "reception unit" of the present invention.

[0059] As described above, the control device 30 of this embodiment receives component information transmitted from the central management device 7 and controls the suction pressure of the vacuum device 50 connected to the suction rolls 15a, 15b that suck oil formed on the front and back surfaces of the workpiece W to be sent to the press processing device 3. The inverter PID controls the motor frequencies of the two vacuum pumps 51, 52 equipped in the vacuum device 50, converging the suction pressure to the set vacuum pressure specified by the component information, thereby controlling the thickness of the oil film formed on the front and back surfaces. The PLC 31 of the control device 30 switches the number of the two vacuum pumps 51, 52 to be driven depending on the set vacuum pressure included in the component information transmitted from the central management device 7. This allows the control device 30 to maintain stable motor rotation using the inverter even at low set vacuum pressures. The control device 30 can stably operate the vacuum device 50, thereby stably controlling the thickness of the oil film. Furthermore, by deactivating one of the two vacuum pumps 51, 52, the suction capacity of the activated vacuum pump can be maximized.

[0060] Furthermore, when the set vacuum pressure is equal to or greater than threshold a1, the PLC 31 drives both vacuum pumps 51 and 52, and when the set vacuum pressure is less than threshold a1, the PLC 31 drives only vacuum pump 51. Depending on whether the set vacuum pressure is equal to or greater than threshold a1, the PLC 31 can automatically switch between driving two or one of the two vacuum pumps 51 and 52. When the set vacuum pressure is less than threshold a1, only vacuum pump 51 is driven, enabling stable control even at low set vacuum pressures. Furthermore, when only vacuum pump 51 is driven, vacuum pump 52 is stopped, allowing the suction capacity of the driven vacuum pump 51 to be maximized.

[0061] Furthermore, the vacuum pumps 51 and 52 have the same suction capacity. When the PLC 31 drives the vacuum pumps 51 and 52, it drives the vacuum pumps 51 and 52 simultaneously and at the same suction pressure. This allows the PLC 31 to easily control the vacuum pumps 51 and 52.

[0062] The present invention is not limited to the above-described embodiment, and various modifications are possible. The press working system 1 of the above-described embodiment is installed in an automobile factory or the like, but is not limited to an automobile factory, and may be installed in other factories. The automobile parts P1 to P4 manufactured by the press working system 1 are just examples, and other automobile parts can also be manufactured.

[0063] The dies set in the press working device 3 are automatically replaced by a die changer 5, but the replacement method can be changed. For example, they may be replaced manually.

[0064] The vacuum device 50 shown in Figure 4 is equipped with two vacuum pumps 51 and 52, which have the same suction capacity, but the suction capacities may be different. For example, as shown in Figure 9, a modified vacuum device 150 is equipped with two vacuum pumps 151 and 152, but the vacuum pump 152 (an example of the "second vacuum pump" of the present invention) is a smaller vacuum pump than the vacuum pump 151. If a significant increase in the oil film thickness is desired, the installed vacuum pressure must be significantly reduced. In this case, by driving only the small vacuum pump 152, the inverter can maintain stable rotation of the motor. This makes it possible to control the vacuum at an extremely low level.

[0065] Although the vacuum device 50 includes two vacuum pumps 51 and 52, it is sufficient to use multiple pumps, for example, three or more. In this case, the higher the set vacuum pressure specified in the component information, the more vacuum pumps should be driven. In this case, even if the set vacuum pressure is at a high level, the vacuum pressure can be stably converged to the set vacuum pressure. Conversely, the lower the set vacuum pressure, the fewer vacuum pumps should be driven. In this case, even if the set vacuum pressure is at a low level, the vacuum pressure can be stably converged to the set vacuum pressure.

[0066] A pair of upper and lower suction rolls 15a, 15b are provided in the suction chamber 11D of the film thickness control device 10, but the number and length of the suction rolls are not limited. For example, two suction rolls may be provided above the workpiece W and two suction rolls may be provided below it.

[0067] The control device 30 operates using a PLC 31, but may also operate using, for example, a CPU instead of the PLC 31. The steps of the vacuum pump control process shown in Fig. 8 are not limited to being executed by the PLC 31, and some or all of the steps may be executed by other electronic devices (for example, an ASIC). The steps of the vacuum pump control process may be distributed and processed by multiple electronic devices (for example, multiple CPUs or multiple PLCs).

[0068] In the above embodiment, the cleaning oil spray nozzles 19a-19d are installed inside the cleaning chamber 11B, but cleaning oil may be sprayed from inside the brush rolls 13a, 13b. In the above embodiment, the oil spray pipe 21 is installed near the upper end of the upper shield plate 18a of the suction chamber 11D, but it may be installed anywhere as long as the sprayed oil does not leak from the outlet 11out, such as in an appropriate location within a range forward of the apex of the suction roll 15a. In addition, in the above embodiment, a configuration in which the operation panel 110 of the control device 30 installed in the press working system 1 is operated is described, but a remote control terminal carried by the operator may be provided with the same functions as the operation panel 110. [Explanation of symbols]

[0069] 1 3 Press processing equipment 7 Central management device 15a, 15b Suction roll 30 Control device 31 PLC 50 Vacuum equipment 51,52 Vacuum pump

Claims

1. A control device that receives component information transmitted from an external device, and that controls the thickness of an oil film layer formed on the front and back surfaces of a workpiece to be sent to a press processing device, by PID-controlling the suction pressure of a vacuum device connected to a suction roll that sucks up oil formed on the front and back surfaces of the workpiece using an inverter to converge to a set vacuum pressure designated by the component information, by PID-controlling the frequency of a vacuum pump motor provided in the vacuum device, the vacuum device comprises a plurality of vacuum pumps; A drive control unit is provided to switch the number of vacuum pumps to be driven among the plurality of vacuum pumps in accordance with the set vacuum pressure. A control device characterized by:

2. The drive control unit The higher the set vacuum pressure, the more the number of vacuum pumps to be driven is increased; 2. The control device according to claim 1, wherein the number of vacuum pumps to be driven decreases as the set vacuum pressure decreases.

3. The vacuum device is a first vacuum pump; A second vacuum pump Equipped with The drive control unit When the set vacuum pressure is equal to or greater than a threshold value, both the first vacuum pump and the second vacuum pump are driven, and when the set vacuum pressure is less than the threshold value, only one of the first vacuum pump and the second vacuum pump is driven. The control device according to claim 1 ,

4. The first vacuum pump and the second vacuum pump have the same suction capacity, The drive control unit When the set vacuum pressure is equal to or greater than a threshold value, the first vacuum pump and the second vacuum pump are driven simultaneously and at the same suction pressure. The control device according to claim 3 ,

5. The suction capacity of the second vacuum pump is lower than the suction capacity of the first vacuum pump, The drive control unit When the set vacuum pressure is less than the threshold value, only the second vacuum pump is driven. The control device according to claim 3 ,

6. a receiving unit that receives a change to the set vacuum pressure, The drive control unit a post-change drive control unit that, when the reception unit receives a change in the set vacuum pressure, switches again the number of the vacuum pumps to be driven in accordance with the changed set vacuum pressure; The control device according to claim 1 ,

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