Control device for processing machinery that processes workpieces on a die cushion

Abstract

The present invention provides a control device for a processing machine that processes a workpiece on a mold cushion. The processing machine processes the workpiece on the mold cushion by applying pressure to a slider according to a processing program that defines multiple motion modes. The control device comprises: a slider position control unit that controls the position of the slider according to the motion mode; a pressure command generation unit that generates a pressure command for the mold cushion according to the motion mode; a pressure detection unit that detects the actual pressure of the mold cushion; a mold cushion speed control unit that controls the speed of the mold cushion based on the deviation between the pressure command and the actual pressure; and a command arrival determination unit that determines whether the deviation is greater than a pressure threshold. Based on the determination result of the command arrival determination unit, the slider position control unit provides a standby period for maintaining the slider position between the motion mode at the determination time and the next motion mode.

Description

Technical Field

[0001] The present invention relates to a control device for a processing machine for processing a workpiece on a die cushion. Background Art

[0002] It is known that processing machines that perform processes such as bending, drawing, and punching have a die cushion that applies a predetermined pressure from the side of a support member that supports a second mold (lower mold) to a slider that supports the movable side of a first mold (upper mold) used in the processing.

[0003] The mold cushion mechanism applies pressure to the workpiece from the moment the slider contacts it until the slider leaves the workpiece. The cushion mechanism tracks the slider's movement and applies force toward the workpiece based on the position of the cushion. To improve machining quality, the cushion must maintain stable pressure on the workpiece while tracking the slider.

[0004] For example, as described in Japanese Patent Application Laid-Open No. 2007-015007, a servo die cushion control system is known, which includes a slider, a plurality of die cushions, and a plurality of control devices that respectively control the plurality of die cushions. The plurality of die cushions use a servo motor as a drive source to generate a force on the slider. The servo die cushion control system includes: a position command unit that generates a position command for each die cushion; a position detection unit that detects the position of each die cushion; a force command unit that generates a force command between each die cushion and the slider; and a force detection unit that detects the force between each die cushion and the slider. The plurality of control devices each include: a first speed command unit that generates a first speed command for the die cushion controlled by each of the plurality of control devices based on the position command and a detection result of the position detection unit; and a second speed command unit that generates a second speed command for the die cushion controlled by each of the plurality of control devices based on the force command and the detection result of the force detection unit. a second speed command for the die cushion pad; a switching determination unit that determines whether control of the die cushion pad should be switched from one of the first command and the second command to the other; and a switching processing unit that switches from one of the first speed command and the second speed command to the other based on a switching signal, the control system further comprising a switching signal generating unit that aggregates determination results of the switching determination units of the plurality of control devices and generates a switching signal and transmits the switching signal to the switching processing units of the plurality of control devices when the switching determination unit determines that the number of the control devices for which control of each die cushion pad should be switched from the first speed command to the second speed command has reached a first predetermined number, or when the switching determination unit determines that the number of the control devices for which control of each die cushion pad should be switched from the second speed command to the first speed command has reached a second predetermined number.

[0005] For example, as described in Japanese Patent Application Laid-Open No. 2008-006459, a stamping machine is known, which includes: a drive motor for performing stamping; a first conversion mechanism that converts the rotational motion of the drive motor into reciprocating motion; a slider that is connected to the first conversion mechanism and reciprocates; and a die cushion that receives a load from the above-mentioned metal die and moves in a state where a workpiece is sandwiched between it and the metal die mounted on the slider. The stamping machine includes: an energy conversion device that supports the above-mentioned die cushion in a manner that the above-mentioned die cushion is movable and generates electricity by the above-mentioned load; and a power line that supplies the above-mentioned electricity to the above-mentioned drive motor.

[0006] For example, as described in Japanese Patent Application Laid-Open No. 2007-038238, there is known a control device for a die cushion mechanism, which uses a servo motor as a driving source to generate a force on a slide of a punching machine, and comprises: a force command unit for commanding the force generated by the die cushion mechanism; a force detection unit for detecting the force generated by the die cushion mechanism on the slide; and a force control unit for executing a force control on the servo motor when a force detection value detected by the force detection unit is equal to or greater than a force command value commanded by the force command unit during a cooperative operation from the mutual collision of the slide and the die cushion mechanism to the separation thereof. force control of the motor; and an initial value setting unit, which sets a new initial stable value each time the above-mentioned slider performs a cycle of stamping action from the initial position to the initial position through the above-mentioned cooperative action with the above-mentioned die cushion mechanism, the initial stable value being a reference for the preliminary command value when the above-mentioned force command unit commands the above-mentioned collision, and the above-mentioned initial value setting unit uses the output value of the above-mentioned force detection unit during the output stable period excluding the time of the above-mentioned cooperative action of the slider and the above-mentioned die cushion mechanism and the predetermined time immediately after the above-mentioned separation in the above-mentioned one cycle of stamping action of the above-mentioned slider to set the above-mentioned initial stable value.

[0007] For example, as described in Japanese Patent Application Laid-Open No. 2007-030009, a control device for a stamping machine is known. The stamping machine includes a slide driven by a servo motor and a die cushion mechanism driven by the servo motor and generating a force on the slide. The control device is configured to control the force and includes: a slide motion command unit for commanding motion of the slide; at least one of a die cushion motion command unit for commanding motion of the die cushion mechanism and a die cushion motion detection unit for detecting motion of the die cushion mechanism; and a slide motion correction unit for correcting a slide motion command value generated by the slide motion command unit based on at least one of a die cushion motion command value generated by the die cushion motion command unit and a die cushion motion detection value detected by the die cushion motion detection unit. Summary of the Invention

[0008] In a processing machine that processes a workpiece on a die cushion by applying pressure to a slide according to a processing program that defines multiple motion patterns, separate slide position control systems and die cushion position control systems are provided. Each control system performs slide position control and die cushion pressure control corresponding to the motion patterns defined in the processing program.

[0009] In a die cushion pressure control system, control is performed so that the pressure applied to the die cushion (hereinafter referred to as "actual pressure") follows a pressure command. If the pressure control system has poor responsiveness due to delays in the control loop or mechanical delays in the die cushion relative to the pressure command, the actual pressure applied to the die cushion may not reach the pressure command, and the die cushion may not generate the pressure required for machining the workpiece. If the actual pressure applied to the die cushion does not reach the pressure command, the slider position control system may cause defects such as wrinkles and cracks in the workpiece when the slider position control is switched from the current operation mode to the next operation mode, resulting in reduced machining quality. Therefore, in a machining machine that processes a workpiece on a die cushion by applying pressure to the slider according to a machining program that defines multiple operation modes, a control device is desired that can prevent the reduction in machining quality caused by the poor responsiveness of the die cushion pressure control system.

[0010] According to one embodiment of the present invention, a control device for a processing machine is provided, wherein the processing machine processes a workpiece on a die cushion by applying pressure with a slide according to a processing program that defines a plurality of motion modes. The control device for the processing machine includes: a slide position control unit that performs position control of the slide according to the motion mode; a pressure command generation unit that generates a pressure command indicating a pressure to be applied to the die cushion according to the motion mode; a pressure detection unit that detects the actual pressure applied to the die cushion; a die cushion speed control unit that performs speed control of the die cushion based on a deviation between the pressure command and the actual pressure applied to the die cushion; and a command arrival determination unit that determines whether the deviation is greater than a predetermined pressure threshold value. Based on a determination result of the command arrival determination unit, the slide position control unit provides a standby period for maintaining the position of the slide at the time of determination by the command arrival determination unit between an motion mode executed at a time of determination by the command arrival determination unit and an motion mode to be executed next to the motion mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention can be more clearly understood by referring to the following drawings.

[0012] Figure 1 This is a block diagram showing a control device for a processing machine having a servo die cushion according to one embodiment of the present disclosure.

[0013] Figure 2 This is a block diagram showing a control device for a processing machine having a hydraulic die cushion according to one embodiment of the present disclosure.

[0014] Figure 3 This is a flowchart showing the operation flow of the control device for a processing machine according to one embodiment of the present disclosure.

[0015] Figure 4A The example illustrates the relationship between the slider position and the die cushion pressure when the slider velocity command and the die cushion pressure command are simultaneously switched before and after different operation modes. This illustrates the application of conventional technology that fails to consider the ability of the actual pressure to follow the pressure command before and after switching the operation mode.

[0016] Figure 4B The relationship between the slider position and the die cushion pressure when the speed command to the slider and the pressure command to the die cushion are switched simultaneously before and after different operation modes is illustrated, showing a case where one embodiment of the present disclosure is applied.

[0017] Figure 5A The relationship between the position of the slider and the pressure of the mold cushion pad when only the pressure command is switched before and after different action modes is illustrated, indicating the application of the existing technology, which means that the followability of the actual pressure to the pressure command before and after the switching of the action mode is not considered.

[0018] Figure 5B The relationship between the position of the slider and the pressure of the die cushion when only the pressure command is switched between different operation modes is illustrated to illustrate a case where one embodiment of the present disclosure is applied.

[0019] Figure 6A The example of the relationship between the position of the slider and the pressure of the die cushion is shown in the case where the actual pressure applied to the die cushion does not reach the pressure command when the slider reaches the lowest point. This illustrates the application of a conventional technique that fails to consider the followability of the actual pressure to the pressure command before and after switching the operating mode.

[0020] Figure 6B The relationship between the position of the slider and the pressure of the die cushion when the actual pressure applied to the die cushion does not reach the pressure command when the slider reaches the lowest point is illustrated to illustrate a case where one embodiment of the present disclosure is applied.

[0021] Figure 7 As an example, a processing machine is described in which a single slide applies pressure to process workpieces placed on a plurality of die cushions.

[0022] Figure 8 This is a flowchart showing the operation flow of the control device for a processing machine according to the first modified example of one embodiment of the present disclosure.

[0023] Figure 9 This is a flowchart showing the operation flow of the control device for a processing machine according to the second modified example of the embodiment of the present disclosure.

[0024] Figures 10A to 10D The operation of a processing machine that processes a workpiece on a die cushion by applying pressure with a slider will be described as an example. DETAILED DESCRIPTION

[0025] The following describes a control device for a processing machine for processing a workpiece on a die cushion with reference to the accompanying drawings. Identical components are denoted by the same reference numerals in the drawings. For ease of understanding, the drawings have been scaled appropriately. The embodiments shown in the drawings are merely examples of implementation and are not limited to the embodiments shown.

[0026] The processing contents of the processing machine for processing the workpiece on the die cushion pad by applying pressure by the slider include bending, drawing and punching. Before explaining the control device of the processing machine of one embodiment of the present disclosure, refer to Figures 10A to 10D The operation of a processing machine that applies pressure from a slide to draw a workpiece on a die cushion will be described. Figures 10A to 10D The operation of a processing machine for processing a workpiece on a die cushion pad by applying pressure to the slide is illustrated. In a processing machine for performing a deep drawing process on a workpiece 200, as shown in FIG. Figure 10A As shown, the workpiece 200 is placed on the mold cushion 2. An upper metal mold 8 is set on the slider 4, and a lower metal mold 9 corresponding to the upper metal mold 8 is set below the mold cushion 2. Figure 10B As shown, when the slider 4 descends toward the direction where the die cushion 2 is located so that the upper die 8 contacts the workpiece 200, the die cushion 2 moves downward in response to the movement of the slider 4 driven by the slider motor 5. When the lower die 9 is pressed against the workpiece 200, the workpiece 200 gradually deforms ( Figure 10C ), when the slider 4 is further lowered, as Figure 10DAs shown, the upper die 8 is pressed against the workpiece 200, completing the drawing process. During this drawing process, the die cushion 2, when the slide 4 contacts the workpiece, contacts the workpiece via the slide 4, applying a predetermined force to the workpiece toward the slide 4 and sandwiching the workpiece between the die cushion 2 and the slide 4. The die cushion pressure control system controls the actual pressure applied to the die cushion so that it follows the pressure command. However, if the pressure control system has poor responsiveness due to delays in the control loop or mechanical delays in the die cushion relative to the pressure command, the actual pressure applied to the die cushion may not reach the pressure command, and the die cushion may not generate the pressure required for machining the workpiece. If the actual pressure applied to the die cushion does not reach the pressure command, the slide position control system may shift from the current operating mode to the next operating mode to perform slide position control. This can cause defects such as wrinkles and cracks in the workpiece, resulting in a decrease in machining quality. The control device for a machining machine according to one embodiment of the present disclosure, described below, can avoid a decrease in machining quality due to the poor responsiveness of the die cushion pressure control system.

[0027] Figure 1 1 is a block diagram showing a control device of a processing machine with a servo die cushion according to an embodiment of the present disclosure. The die cushion mechanism in the processing machine according to an embodiment of the present disclosure may be a servo die cushion or a hydraulic die cushion. Figure 1 An example in which the die cushion mechanism is composed of a servo die cushion is described.

[0028] The processing machine 100 includes a slide 4 driven by a slide motor 5 and a die cushion 2 that moves in accordance with the movement of the slide 4 .

[0029] The die cushion 2, which is comprised of a servo die cushion, is driven by a die cushion motor 3 controlled by a die cushion speed control unit 14. The die cushion 2 has the following functions: when the slide 4 contacts a workpiece, the die cushion 2 contacts the slide 4 via the workpiece, applies a predetermined force toward the slide 4, and sandwiches the workpiece between the die cushion 2 and the slide 4.

[0030] The mold cushion 2 is connected to the shaft of the mold cushion motor 3 via, for example, a belt / pulley mechanism and a ball screw mechanism. The belt / pulley mechanism and the ball screw mechanism convert the rotational motion of the mold cushion motor 3 into linear motion, thereby enabling the mold cushion 2 to be raised and lowered. Alternatively, the mold cushion 2 may be connected to the mold cushion motor 3 via, for example, gears. Alternatively, the mold cushion 2 may be directly connected (coupled) to the mold cushion motor 3.

[0031] The slider 4 is connected to the shaft of the slider motor 5 via, for example, a belt / pulley mechanism and a ball screw mechanism. The belt / pulley mechanism and the ball screw mechanism convert the rotational motion of the slider motor 5 into linear motion, thereby enabling the slider 4 to be raised and lowered. As an alternative, the slider 4 may be connected to the slider motor 5 via, for example, gears, or may be directly connected (coupled) to the slider motor 5.

[0032] A control device 1 according to one embodiment of the present disclosure controls a processing machine 100 according to a processing program 17 defining a plurality of operation modes, so that a workpiece on a die cushion 2 is processed by applying pressure via a slide 4. The control device 1 for controlling the processing machine 100 includes a slide position control unit 11, a pressure command generation unit 12, a pressure detection unit 13, a die cushion speed control unit 14, and a command arrival determination unit 15. Furthermore, the control device 1 includes a speed command generation unit 16 and a host control unit 18.

[0033] The upper control unit 18 controls the speed instruction generating unit 16 for controlling the slide 4 and the pressure instruction generating unit 12 for controlling the die cushion 2 according to the processing program 17 that defines a plurality of operation modes. Figure 1 In the embodiment, the upper control unit 18 is provided as a common upper control unit for the slider position control unit 11 and the die cushion speed control unit 14. As an alternative, for example, the slider position control unit 11 and the die cushion speed control unit 14 may each be provided with an independent upper control unit 18, and each of these independent upper control units 18 may be provided with a processing program 17 that specifies an operation mode for the slider position control unit 11 and a processing program 17 that specifies an operation mode for the die cushion speed control unit 14.

[0034] The machining program 17 is defined based on the machining content of the machining machine 100. The die cushion 2 and slider 4 operate based on the machining content of the machining machine 100. Multiple motion patterns are defined in the machining program 17. Each motion pattern defined in the machining program 17 is composed of a combination of a set of identical motions of the die cushion 2 and a corresponding set of identical motions of the slider 4. If at least one of the velocity or acceleration of the slider 4 and the pressure command to the die cushion 2 changes at a certain point in time, the motion pattern is considered to have changed at that point in time. For example, if multiple sets of identical motions of the die cushion 2 exist during a single set of identical motions of the slider 4, a single motion pattern is formed, with the set of identical motions among the multiple motions being considered as a unit. To give a specific example, while the slide 4 is descending at the same speed in the direction of the workpiece (i.e., the direction of the die cushion 2), if there are two pressure commands for the die cushion 2, a "first value" and a "second value," one operation pattern is formed by combining the slide 4 descending at the same speed and the die cushion 2 operating in accordance with the pressure command of the first value, and another operation pattern is formed by combining the slide 4 descending at the same speed and the die cushion 2 operating in accordance with the pressure command of the second value. Furthermore, if, for example, during a set of identical operations of the die cushion 2, there are multiple sets of identical operations of the slide 4, one operation pattern is formed with the set of identical operations among the multiple operations as a single unit. To give a specific example, when a pressure command of a certain value is given to the die cushion 2 and two speed commands for the slide 4 exist, namely, a "first value" and a "second value," there are two operation modes: one in which the die cushion 2 is operated according to the pressure command and the slide 4 is lowered according to the speed command of the first value; and another in which the die cushion 2 is operated according to the pressure command and the slide 4 is lowered according to the speed command of the second value.

[0035] The speed command generating unit 16 generates a speed command for the slide motor 5. The speed command generated by the speed command generating unit 16 is a speed command based on the machining program 17 and is sent to the slide position control unit 11.

[0036] The slide position control unit 11 performs position control of the slide 4 according to an operation pattern specified in the machining program 17. Therefore, the slide position control unit 11 includes a slide servo control unit 21 and a slide speed detection unit 22.

[0037] The slider speed detection unit 22 detects the speed of the slider 4. The slider servo control unit 21 controls the rotational drive of the slider motor 5 based on the speed command generated by the speed command generation unit 16 and the speed of the slider 4 detected by the slider speed detection unit 22. An inverter (not shown) is connected to the slider servo control unit 21, which converts DC power into AC power for driving the slider motor 5. The slider servo control unit 21 controls the rotational drive of the slider motor 5 by controlling the power conversion operation of the inverter. By controlling the rotational drive of the slider motor 5, the position (or speed) of the slider 4 is controlled. While an example of controlling the speed of the slider 4 has been described herein, the speed of the slider motor 5 itself may alternatively be controlled. In this case, the speed command generation unit 16 generates a speed command for the slider motor 5, the slider speed detection unit 22 detects the rotational speed of the slider motor 5, and the slider servo control unit 21 controls the rotational drive of the slider motor 5 based on the speed command for the slider motor 5 and the rotational speed of the slider motor 5 detected by the slider speed detection unit 22.

[0038] The pressure command generator 12 generates a pressure command according to the operation mode, which instructs the pressure to be applied to the die cushion 2. The pressure command generated by the pressure command generator 12 is based on the machining program 17 and is sent to the die cushion speed controller 14.

[0039] The pressure detection unit 13 detects the actual pressure applied to the die cushion 2. The actual pressure applied to the die cushion 2 is the actual pressure applied by the die cushion 2 to the workpiece, that is, the pressure generated between the die cushion 2 and the slider 4. The pressure detection unit 13 is, for example, mounted on the portion of the die cushion 2 that the workpiece contacts when pressure is applied by the slider 4, and is capable of detecting the actual pressure of the workpiece acting on the die cushion 2 (that is, the reaction force of the force applied by the die cushion 2 to the slider 4). A pressure sensor or the like is typically used as such a pressure detection unit 13. As an alternative, the pressure detection unit 13 can be mounted on the portion of the slider 4 that the workpiece contacts when pressure is applied. In this case, the actual pressure applied to the slider 4 detected is the reaction force of the force applied by the die cushion 2 to the slider 4, similar to the case where the pressure detection unit 13 is mounted on the die cushion 2. Furthermore, as a further alternative, the actual pressure of the workpiece can be obtained through computational processing.

[0040] The die cushion speed control unit 14 controls the speed of the die cushion 2 based on the deviation between the pressure command received from the pressure command generating unit 12 and the actual pressure applied to the die cushion 2 detected by the pressure detecting unit 13, in accordance with the operation pattern specified in the machining program 17. Therefore, the die cushion speed control unit 14 includes a die cushion servo control unit 32 and a die cushion speed detecting unit 31.

[0041] The die cushion speed detection unit 31 detects the speed of the die cushion 2. The die cushion servo control unit 32 controls the rotational drive of the die cushion motor 3 based on the deviation between the pressure command generated by the pressure command generation unit 12 and the actual pressure applied to the die cushion 2 detected by the pressure detection unit 13. An inverter (not shown) is connected to the die cushion servo control unit 32, which converts DC power to output AC power for driving the die cushion motor 3. The die cushion servo control unit 32 controls the rotational drive of the die cushion motor 3 by controlling the power conversion operation of the inverter. In addition, the example of controlling the speed of the die cushion 2 is described here, but as an alternative, the speed of the die cushion motor 3 itself can be controlled. At this time, the pressure command generating unit 12 generates a pressure command for the die cushion motor 3, the die cushion speed detecting unit 31 detects the rotational speed of the die cushion motor 3, and the die cushion servo control unit 32 controls the rotational drive of the die cushion motor 3 based on the speed command for the die cushion motor 3 and the rotational speed of the die cushion motor 3 detected by the die cushion speed detecting unit 31. By controlling the rotational drive of the die cushion motor 3, the lifting speed of the die cushion 2 is controlled, and as a result, the pressure to which the die cushion 2 is subjected is controlled.

[0042] The command arrival determination unit 15 determines whether the difference between the pressure command generated by the pressure command generation unit 12 and the actual pressure applied to the die cushion pad 2 detected by the pressure detection unit 13 is greater than a predetermined pressure threshold, thereby determining whether the pressure command and the actual pressure of the die cushion pad 2 are consistent. Specifically, the pressure threshold is used to determine whether the pressure command generated by the pressure command generation unit 12 is consistent with the actual pressure applied to the die cushion pad 2 detected by the pressure detection unit 13. The pressure threshold is appropriately set based on the operating environment of the processing machine 100, for example, to a value of approximately several percent of the maximum actual pressure detected by the pressure detection unit 13. For example, if the pressure threshold is set to 0 (zero), a complete match between the pressure command and the actual pressure of the die cushion pad 2 can be detected. The command arrival determination unit 15 determines whether the difference between the pressure command and the actual pressure is greater than the pressure threshold at a predetermined time (e.g., tens to hundreds of microseconds) prior to the time when the operating mode executed by the processing machine 100 is switched. Furthermore, the command arrival determination unit 15 also determines whether the difference between the pressure command and the actual pressure is greater than the pressure threshold during the standby period described below.

[0043] Based on the determination result of the command arrival determination unit 15, the slider position control unit 11 sets a standby period between the operating mode currently being executed at the time of the command arrival determination unit 15's determination and the operating mode immediately following that operating mode. This standby period is used to maintain the position of the slider 4 at the time of the command arrival determination unit 15's determination. More specifically, when the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is greater than a pressure threshold, the slider position control unit 11 sets a standby period between the operating mode currently being executed at the time of the command arrival determination unit 15's determination and the operating mode immediately following that operating mode. This standby period is used to maintain the position of the slider 4 at the time when the command arrival determination unit 15 determined that the deviation between the pressure command and the actual pressure was greater than the pressure threshold. During this standby period, the slider position control unit 11 controls the slider 4 to maintain the position at the time when the command arrival determination unit 15 determined that the deviation between the pressure command and the actual pressure was greater than the pressure threshold. However, the determination process of the command arrival determination unit 15 is also performed during this period. During this standby period, if the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is less than the pressure threshold, the slide position control unit 11 ends the standby period and performs slide position control corresponding to the next operating mode to be executed (i.e., the operating mode following the standby period). The smaller the pressure threshold used by the command arrival determination unit 15 to determine whether the pressure command and the actual pressure are consistent or inconsistent, the higher the accuracy of the consistency between the pressure command and the actual pressure, and the higher the processing quality of the processing machine 100. However, it takes time to exit the standby period, which may result in a longer processing time for the processing machine 100.

[0044] Thus, according to the control device 1 of the processing machine 100 according to one embodiment of the present disclosure, when the deviation between the pressure command and the actual pressure of the die cushion 2 exceeds a pressure threshold (i.e., when the actual pressure applied to the die cushion 2 does not reach the pressure command), a standby period is set in which the current position of the slider 4 is maintained, without transitioning from the currently executed operating mode to the next operating mode. During the standby period, if the deviation between the pressure command and the actual pressure falls below the pressure threshold, it can be said that the actual pressure applied to the die cushion 2 has substantially reached the pressure command, and the die cushion is generating the pressure required for machining the workpiece. Therefore, the standby period ends and transition is executed to the next operating mode (i.e., the operating mode following the standby period). The slider position control unit 11 performs position control of the slider 4 corresponding to the transitioned operating mode. According to one embodiment of the present disclosure, since transition is not made to the next operating mode when the actual pressure applied to the die cushion 2 does not reach the pressure command, defects such as wrinkles and cracks in the workpiece are prevented, and degradation in machining quality due to the poor responsiveness of the die cushion 2 pressure control system can be avoided.

[0045] While the above description describes an example in which the die cushion mechanism is composed of a servo die cushion, the die cushion mechanism in the processing machine according to an embodiment of the present disclosure may be a hydraulic die cushion.

[0046] Figure 2 This is a block diagram illustrating a control device for a processing machine equipped with a hydraulic die cushion according to one embodiment of the present disclosure. For example, a cushion pad of a die cushion 2 comprised of a hydraulic die cushion is connected to a cylinder 81. The die cushion 2 comprised of a hydraulic die cushion can be raised or lowered by adjusting the oil volume in the oil tank 7 and cylinder 81 via a valve 6 controlled by a die cushion speed control unit 14. The die cushion speed control unit 14 includes a valve control unit 33 and a die cushion speed detection unit 31. The die cushion 2 speed is controlled to control the pressure applied to the die cushion 2. The valve control unit 33 controls the opening and closing of the valve 6 based on the deviation between the pressure command generated by the pressure command generation unit 12 and the actual pressure applied to the die cushion 2 as detected by the pressure detection unit 13, thereby adjusting the oil volume in the oil tank 7 and cylinder 81. Increasing the oil volume in the cylinder 81 increases the pressure on the workpiece acting on the die cushion 2 (i.e., the reaction force to the force applied by the die cushion 2 to the slide 4). In addition, regarding the circuit components other than the valve 6, the oil tank 7, the cylinder 81 and the valve control unit 33, Figure 1The circuit components shown are the same, so the same circuit components are given the same reference numerals and detailed descriptions of the circuit components are omitted. In addition, as a modified example of the hydraulic die cushion, an air die cushion can be used in which the oil in the oil tank 7 is replaced with (air).

[0047] The slide position control unit 11, pressure command generating unit 12, die cushion speed control unit 14, command arrival determination unit 15, speed command generating unit 16, and host control unit 18 can be implemented, for example, as a software program, or as a combination of various circuits and software programs. In this case, the functions of each unit can be implemented by executing the software program on a processing unit such as a CPU, MPU, or DSP. Alternatively, the units can be implemented as a semiconductor integrated circuit with a software program written therein, which implements the functions of the slide position control unit 11, pressure command generating unit 12, die cushion speed control unit 14, command arrival determination unit 15, speed command generating unit 16, and host control unit 18. Furthermore, the slide position control unit 11, pressure command generating unit 12, die cushion speed control unit 14, command arrival determination unit 15, speed command generating unit 16, and host control unit 18 can be provided, for example, within a main control unit (not shown) of the processing machine 100. In this case, the functions of each part can be realized by causing a calculation processing device such as a CPU, an MPU, and a DSP in the main control device of the processing machine 100 to execute the software program.

[0048] Figure 3 This is a flowchart showing the operation flow of the control device for a processing machine according to one embodiment of the present disclosure. Figure 1 or Figure 2 In the processing machine 100 shown, a workpiece on the die cushion 2 is processed by applying pressure via the slider 4 .

[0049] In step S101 , the slide position control unit 11 controls the position of the slide 4 based on the speed command generated by the speed command generation unit 16 and the speed of the slide 4 detected by the slide speed detection unit 22 in accordance with the operation pattern specified in the machining program 17 .

[0050] In step S102 , the pressure command generating unit 12 generates a pressure command for instructing the pressure to be applied to the die cushion 2 in accordance with the operation pattern specified in the machining program 17 .

[0051] In step S103 , the pressure detecting section 13 detects the actual pressure applied to the die cushion 2 .

[0052] In step S104 , the die cushion speed control unit 14 controls the speed of the die cushion 2 based on the deviation between the pressure command received from the pressure command generation unit 12 and the actual pressure applied to the die cushion 2 detected by the pressure detection unit 13 in accordance with the operation pattern specified in the machining program 17 .

[0053] Step S105 is executed at a predetermined time (e.g., tens to hundreds of microseconds) before the time when the operation mode executed by the processing machine 100 is switched. In step S105, the command arrival determination unit 15 determines whether the difference between the pressure command generated by the pressure command generation unit 12 and the actual pressure applied to the die cushion 2 detected by the pressure detection unit 13 is greater than a pressure threshold.

[0054] When it is determined in step S105 that the deviation between the pressure instruction and the actual pressure is greater than the pressure threshold, the process proceeds to step S107. When it is not determined that the deviation between the pressure instruction and the actual pressure is greater than the pressure threshold (that is, the deviation between the pressure instruction and the actual pressure is below the pressure threshold), the process proceeds to step S106.

[0055] In step S107, the slider position control unit 11 sets a standby period between the currently executed operation mode and the operation mode executed next to the currently executed operation mode, and maintains the position of the slider 4 at the time of executing step S105 during this standby period. During the standby period, the slider position control unit 11 controls the slider 4 so that the position at the time of executing step S105 is maintained, and then executes the process of step S108.

[0056] During the standby period, step S108 is executed. In step S108, the command arrival determination unit 15 determines whether the difference between the pressure command generated by the pressure command generation unit 12 and the actual pressure applied to the die cushion 2, as detected by the pressure detection unit 13, is below a pressure threshold. If the command arrival determination unit 15 determines in step S108 that the difference between the pressure command and the actual pressure is below the pressure threshold, it can be said that the pressure required for machining the workpiece is generated on the die cushion. Therefore, the slide position control unit 11 ends the standby period and proceeds to step S106. On the other hand, if the command arrival determination unit 15 does not determine in step S108 that the difference between the pressure command and the actual pressure is below the pressure threshold, it can be said that the pressure required for machining the workpiece is still not generated on the die cushion. Therefore, the standby period continues, maintaining the position of the slide 4 at the time of step S105. Then, the process returns to step S107.

[0057] In step S106 , the slider position control unit 11 performs position control of the slider 4 corresponding to the next operation mode, and returns to step S102 .

[0058] Next, several specific examples will be given regarding the relationship between the position of the slide 4 and the pressure of the die cushion 2 in the control device 1 of the processing machine 100 according to the embodiment of the present disclosure.

[0059] Figure 4A The example illustrates the relationship between the slider position and the die cushion pressure when the slider velocity command and the die cushion pressure command are simultaneously switched before and after different operation modes. This illustrates the application of conventional technology that fails to consider the ability of the actual pressure to follow the pressure command before and after switching the operation mode. Figure 4B The relationship between the slider position and the die cushion pressure when the speed command to the slider and the pressure command to the die cushion are switched simultaneously before and after different operation modes is illustrated, showing a case where one embodiment of the present disclosure is applied.

[0060] exist Figure 4A and Figure 4B In the example shown, the slider 4 and the die cushion 2 operate in mode A from time 0 to time t1. At time t1, mode A switches to mode B, at time t2, mode B switches to mode C, and at time t3, mode C switches to mode D. The speed command for the slider 4 differs between modes A through D, while the pressure command for the die cushion 2 differs only between mode A and modes B through D. Furthermore, in mode C from time t2 to time t3, the slider 4 reaches its lowest point, and the speed command is zero. In mode D after time t3, the slider 4 is raised while maintaining the pressure applied to the die cushion 2.

[0061] Here, consider the case where the actual pressure of the die cushion 2 does not reach the pressure command at time t1 when switching from mode A to mode B. In mode A, the slider 4 is lowered at a certain speed and a certain pressure is given to the die cushion 2. When the slider 4 contacts the workpiece, the processing of the metal mold set on the slider 4 begins, and pressure is generated on the die cushion 2 where the workpiece is placed. Figure 4A As shown, in the conventional technology that does not consider the followability of the actual pressure to the pressure command, when the operation mode is switched from mode A to mode B at time t1, the actual pressure of the die cushion 2 does not reach the pressure command at time t1, and defects such as wrinkles and cracks occur in the workpiece during processing at this time. Figure 4BAs shown, according to a control device 1 according to one embodiment of the present disclosure, at time t1 when the operating mode switches from mode A to mode B, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is greater than the pressure threshold. Therefore, the slider position control unit 11 establishes a standby period between the currently executing mode A and the operating mode B executed after mode A. During this standby period, the slider position control unit 11 maintains the position of the slider 4 at time t1, the time when the command arrival determination unit 15 determined that the deviation between the pressure command and the actual pressure was greater than the pressure threshold. During this standby period, the slider position control unit 11 controls the slider 4 to maintain the position at time t1. Subsequently, the actual pressure gradually approaches the pressure command. At time t4 when the actual pressure reaches the pressure command, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is below the pressure threshold. Therefore, the slider position control unit 11 ends this standby period at time t4 and begins position control of the slider 4 based on mode B. Thus, according to one embodiment of the present disclosure, because the actual pressure has not reached the pressure command at time t1, the end point of mode A, the mode is not shifted to mode B. Instead, the mode is shifted to mode B after time t4, when the actual pressure reaches the pressure command. Therefore, machining is performed according to mode B while the die cushion 2 generates the pressure required for machining the workpiece. This prevents defects such as wrinkles and cracks from occurring in the workpiece, as has been the case with conventional methods.

[0062] Figure 5A The relationship between the position of the slider and the pressure of the mold cushion pad when only the pressure command is switched before and after different action modes is illustrated, indicating the application of the existing technology, which means that the followability of the actual pressure to the pressure command before and after the switching of the action mode is not considered. Figure 5B The relationship between the position of the slider and the pressure of the die cushion when only the pressure command is switched between different operation modes is illustrated to illustrate a case where one embodiment of the present disclosure is applied.

[0063] exist Figure 5A and Figure 5B In the example shown, the slider 4 and the die cushion 2 operate in mode E from time 0 to time t1. At time t1, mode E switches to mode F, at time t2, mode F switches to mode G, and at time t3, mode G switches to mode H. While the slider 4 descends at a constant speed from time 0 to time t2, the pressure command is switched to a larger value at time t1. That is, in modes E and F, the speed command for the slider 4 is the same, while the pressure command for the die cushion 2 is different. Furthermore, in mode G from time t2 to time t3, the slider 4 reaches its lowest point, and the speed command is zero. In mode H after time t3, the slider 4 is raised while maintaining the pressure applied to the die cushion 2.

[0064] Here, consider the case where the actual pressure of the die cushion 2 does not reach the pressure command at time t1 when switching from mode E to mode F. In mode E, the slider 4 is lowered at a certain speed, and a certain pressure is given to the die cushion 2. When the slider 4 contacts the workpiece, the processing of the metal mold set on the slider 4 begins, and pressure is generated in the die cushion 2 on which the workpiece is placed. Figure 5A As shown, in the conventional technology that does not consider the followability of the actual pressure to the pressure command, when the operation mode is switched from mode E to mode F at time t1, the actual pressure of the die cushion 2 does not reach the pressure command at time t1, and defects such as wrinkles and cracks occur in the workpiece during processing at that time. Figure 5B As shown, according to a control device 1 according to one embodiment of the present disclosure, at time t1 when the operating mode switches from mode E to mode F, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure exceeds the pressure threshold. Therefore, the slider position control unit 11 establishes a standby period between the currently executing mode E and the operating mode F executed after mode E. During this standby period, the slider position control unit 11 maintains the position of the slider 4 at time t1, the time when the command arrival determination unit 15 determined that the deviation between the pressure command and the actual pressure exceeded the pressure threshold. During this standby period, the slider position control unit 11 controls the slider 4 to maintain the position at time t1. Subsequently, the actual pressure gradually approaches the pressure command, and at time t4 when the actual pressure reaches the pressure command, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is below the pressure threshold. Consequently, the slider position control unit 11 ends this standby period at time t4 and begins position control of the slider 4 in mode F. Thus, according to one embodiment of the present disclosure, because the actual pressure has not reached the pressure command at time t1, the end point of mode E, the mode is not shifted to mode F. Instead, the mode is shifted to mode F after time t4, when the actual pressure reaches the pressure command. Therefore, machining is performed according to mode F while the die cushion 2 generates the pressure required for machining the workpiece. This prevents defects such as wrinkles and cracks from occurring in the workpiece, as has been the case with conventional methods.

[0065] Figure 6A The example of the relationship between the position of the slider and the pressure of the die cushion is shown in the case where the actual pressure applied to the die cushion does not reach the pressure command when the slider reaches the lowest point. This illustrates the application of a conventional technique that fails to consider the followability of the actual pressure to the pressure command before and after switching the operating mode. Figure 6BThe relationship between the position of the slider and the pressure of the die cushion when the actual pressure applied to the die cushion does not reach the pressure command when the slider reaches the lowest point is illustrated to illustrate a case where one embodiment of the present disclosure is applied.

[0066] exist Figure 6A and Figure 6B In the example shown, the slider 4 and the die cushion 2 operate in mode I from time 0 to time t1. At time t1, mode I switches to mode J, and at time t2, mode J switches to mode K. The pressure command applied to the die cushion 2 is constant in modes I through K. The slider 4 descends at a constant speed from time 0 to time t1 (mode I). In mode J from time t1 to time t2, the slider 4 reaches its lowest point, and the speed command is zero. In mode K after time t2, the slider 4 rises, causing the actual pressure applied to the die cushion 2 to decrease.

[0067] Here, consider the case where the actual pressure of the die cushion 2 does not reach the pressure command in mode J from time t1 to time t2 when the slider 4 reaches the lowest point. In mode J, the slider 4 is in contact with the workpiece, and processing is performed by the upper metal mold set on the slider 4 and the lower metal mold set below the die cushion 2. Although pressure is generated in the die cushion 2 where the workpiece is placed, this pressure does not reach the pressure command, and the pressure required for processing the workpiece is not generated in the die cushion 2. Figure 6A As shown, in the conventional technology that does not consider the ability of the actual pressure to follow the pressure command, in mode J from time t1 to time t2 when the slider 4 reaches its lowest point, the actual pressure applied to the die cushion 2 does not reach the pressure command. When the die cushion 2 does not generate the pressure required for processing the workpiece, the process switches to mode K at time t2 and processing is performed. Because the die cushion 2 does not generate the pressure required for processing the workpiece when the slider 4 is at its lowest point, defects such as wrinkles and cracks occur in the workpiece. In contrast, Figure 6BAs shown, according to the control device 1 of one embodiment of the present disclosure, at time t1 when the slider 4 reaches its lowest point, the actual pressure applied to the die cushion 2 does not reach the pressure command. Consequently, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure exceeds the pressure threshold. The slider position control unit 11 establishes a standby period between the currently executed mode I and the action mode J executed after mode I. During this standby period, the slider 4 is maintained at the position at time t1, the time when the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure exceeds the pressure threshold. Thus, during this standby period, the slider position control unit 11 controls the slider 4 to maintain its current position, namely, its lowest point. Then, with the slider 4 at its lowest point, the actual pressure gradually approaches the pressure command. At time t4 when the actual pressure reaches the pressure command, the command arrival determination unit 15 determines that the deviation between the pressure command and the actual pressure is below the pressure threshold. The slider position control unit 11 terminates this standby period and begins position control of the slider 4 in mode J. Since the slider 4 is at its lowest point even in Mode J, it remains at its lowest point in Mode J from the start of the standby period, which begins at time t1 and ends at time t4. Specifically, the slider 4 remains at its lowest point until the die cushion 2 generates the pressure required for machining the workpiece. Thus, according to one embodiment of the present disclosure, since the actual pressure has not reached the pressure command at time t1, the end point of Mode I, the process does not transition to Mode J. Instead, the process transitions to Mode K after the actual pressure reaches the pressure command at time t4. Therefore, because machining in Mode J is performed while the die cushion 2 generates the pressure required for machining the workpiece, defects such as wrinkles and cracks in the workpiece, as has been the case with conventional processes, are avoided.

[0068] An embodiment of the present disclosure can also be applied to a control device for a processing machine that processes workpieces placed on multiple die cushions by applying pressure with a single slider. Below, such a control device for a processing machine is described as a modified example of an embodiment of the present disclosure.

[0069] Figure 7 As an example, a processing machine is described in which a single slide applies pressure to process workpieces placed on a plurality of die cushions.

[0070] exist Figure 7 In the example in which the die cushion mechanism is composed of a servo die cushion, Figure 7 For reference Figure 1 The slide position control unit 11 , pressure command generating unit 12 , pressure detecting unit 13 , die cushion speed control unit 14 , command arrival determination unit 15 , speed command generating unit 16 , and host control unit 18 described above are not shown.

[0071] The slider 4 is driven by the slider motors 5-1 and 5-2. The plurality of die cushion pads 2-1, 2-2 and 2-3 are driven by the die cushion pad motors 3-1, 3-2 and 3-3 respectively. Figure 7 In the figure, as an example, the number of mold cushion pads is set to 3, but the number of mold cushion pads can also be 2 or 4 or more. The workpiece is placed on each mold cushion pad 2-1, 2-2 and 2-3, and multiple workpieces can be processed simultaneously by the lifting and lowering action of a single slider 4. Depending on the processing content of each workpiece, the pressure instructions for the mold cushion pads 2-1, 2-2 and 2-3 are sometimes different. Since the pressure control of each mold cushion pad 2-1, 2-2 and 2-3 is performed independently, the followability of the actual pressure to the pressure instruction is different for each mold cushion pad 2-1, 2-2 and 2-3. In the first variant and the second variant of an embodiment of the present disclosure, when the deviation between the pressure instruction and the actual pressure for at least one mold cushion pad among the multiple mold cushion pads 2-1, 2-2 and 2-3 is greater than a predetermined pressure threshold, a standby period is set. Furthermore, since the pressure control of the die cushion pads 2-1, 2-2, and 2-3 is performed independently, the timing of switching the pressure command differs for each die cushion pad 2-1, 2-2, and 2-3, and thus the timing of switching the operation mode also differs. Therefore, when the operation mode of at least one of the die cushion pads 2-1, 2-2, and 2-3 is switched, the command arrival determination unit 15 performs determination processing for all of the die cushion pads 2-1, 2-2, and 2-3 at a predetermined time (e.g., tens to hundreds of microseconds) before the time of switching the operation mode.

[0072] Figure 8 This is a flowchart showing the operation flow of the control device of the processing machine according to the first modified example of the embodiment of the present disclosure. Figure 7 In the processing machine shown, a single slider 4 is used to apply pressure to process the workpieces on the die cushions 2-1, 2-2, and 2-3. Figure 7 In the embodiment, three die cushion pads are provided as an example, but the number of die cushion pads may be two or four or more.

[0073] In step S201 , the slide position control unit 11 performs position control of the single slide 4 based on the speed command generated by the speed command generation unit 16 and the speed of the slide 4 detected by the slide speed detection unit 22 according to the operation pattern specified in the machining program 17 .

[0074] In step S202 , the pressure command generating unit 12 generates pressure commands for the die cushions 2 - 1 , 2 - 2 , and 2 - 3 according to the operation pattern specified in the machining program 17 .

[0075] In step S203 , the pressure detecting section 13 detects actual pressure applied to each of the die cushion pads 2 - 1 , 2 - 2 , and 2 - 3 .

[0076] In step S204, the die cushion speed control unit 14 performs speed control on each of the die cushion pads 2-1, 2-2, and 2-3 based on the deviation between the pressure command corresponding to the die cushion pad and the actual pressure according to the operation pattern specified in the processing program 17.

[0077] Step S205 is executed at a predetermined time (e.g., tens to hundreds of microseconds) before the switching of the operating mode executed by the processing machine 100. In step S205, the command arrival determination unit 15 compares the deviation between the pressure command and the actual pressure corresponding to each of the die cushions 2-1, 2-2, and 2-3 with the pressure threshold. If the command arrival determination unit 15 determines that the deviation of at least one of the die cushions 2-1, 2-2, and 2-3 is greater than the pressure threshold, the process proceeds to step S207. If the command arrival determination unit 15 does not determine that the deviation of at least one of the die cushions 2-1, 2-2, and 2-3 is greater than the pressure threshold (i.e., if the deviation of at least one of the die cushions 2-1, 2-2, and 2-3 is determined to be less than the pressure threshold), the process proceeds to step S206.

[0078] If, as a result of the comparison by the command arrival determination unit 15 in step S205, it is determined that the deviation of at least one of the die cushions 2-1, 2-2, and 2-3 is greater than the pressure threshold, step S207 is executed. In step S207, the slider position control unit 11 sets a standby period between the currently executed operation mode and the operation mode that follows it, during which the position of the slider 4 at the time of executing step S205 is maintained. During the standby period, the slider position control unit 11 controls the slider 4 to maintain its position and proceeds to step S208. Thus, according to the first modified example, even if the actual pressure of one of the multiple die cushions 2-1, 2-2, and 2-3 does not reach the pressure command at a predetermined time (e.g., tens to hundreds of microseconds) before the time of switching the operation mode, the slider 4 position at that time is maintained.

[0079] During the standby period, step S208 is executed. In step S208, the command arrival determination unit 15 compares the deviation between the pressure command and the actual pressure corresponding to each of the mold cushion pads 2-1, 2-2, and 2-3 with the pressure threshold. If the command arrival determination unit 15 determines that the deviation for at least one of the mold cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold, the process proceeds to step S206. If the command arrival determination unit 15 does not determine that the deviation for at least one of the mold cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold, the process returns to step S207.

[0080] In step S206 , the slider position control unit 11 performs position control of the slider 4 corresponding to the next operation mode, and returns to step S202 .

[0081] As described above, in the first modified example, in the determination process of the command arrival determination unit 15 in step S208 executed during the standby period, whether or not to terminate the standby period is determined based on whether or not the deviation of at least one of the die cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold. In the second modified example described below, whether or not to terminate the standby period is determined based on whether or not the deviation of all of the die cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold.

[0082] Figure 9 This is a flowchart showing the operation flow of the control device of the processing machine of the second modified example of one embodiment of the present disclosure. Figure 7 In the processing machine shown, a single slide 4 is used to apply pressure to process the workpieces on the die cushion using motors 3-1, 3-2, and 3-3. Figure 7 In the embodiment, three die cushion pads are provided as an example, but the number of die cushion pads may be two or four or more.

[0083] Each process and reference of steps S301 to S307 Figure 8The processes of steps S201 to S207 described above are identical. Step S308 is executed during the standby period. In step S308, the command arrival determination unit 15 compares the deviation between the pressure command and the actual pressure corresponding to each of the mold cushion pads 2-1, 2-2, and 2-3 with the pressure threshold. If the command arrival determination unit 15 determines that the deviation for all of the mold cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold, the process proceeds to step S306. If the command arrival determination unit 15 does not determine that the deviation for all of the mold cushion pads 2-1, 2-2, and 2-3 is below the pressure threshold (i.e., if the deviation for at least one of the mold cushion pads 2-1, 2-2, and 2-3 is greater than the pressure threshold), the process returns to step S307. In the second modified example, during the standby period for maintaining the current position of the slider 4, the standby period does not end unless it is determined that the deviation of all of the plurality of die cushions 2-1, 2-2, and 2-3 is below the pressure threshold. Therefore, defects such as wrinkles or cracks are not generated in all of the workpieces placed on the plurality of die cushions 2-1, 2-2, and 2-3, and a decrease in processing quality due to poor responsiveness of the pressure control system of the die cushion 2 can be more reliably avoided.

[0084] Thus, according to the first and second modified examples of one embodiment of the present disclosure, even in a processing machine that processes workpieces located on multiple die cushions by applying pressure with a single slide, it is possible to avoid a decrease in processing quality due to poor responsiveness of the die cushion pressure control system.

[0085] According to one embodiment of the present disclosure, a control device can be implemented in a processing machine that processes a workpiece on a die cushion by applying pressure with a slide according to a processing program that defines multiple motion patterns. The control device can avoid a decrease in processing quality caused by poor responsiveness of a die cushion pressure control system.

Claims

1. A control device for a processing machine that processes a workpiece on a die cushion by applying pressure by a slider according to a processing program that specifies a plurality of motion modes. It is characterized by: The control device has: a slider position control unit configured to control the position of the slider according to the operation mode; a pressure command generating unit for generating a pressure command for indicating a pressure to be applied to the die cushion according to the operation mode; a pressure detection unit for detecting actual pressure applied to the mold cushion; a die cushion pad speed control unit configured to control the speed of the die cushion pad based on a deviation between the pressure command and an actual pressure applied to the die cushion pad; as well as The instruction reaches the determination unit, which determines whether the above deviation is greater than a predetermined pressure threshold. The slider position control unit sets a standby period between the action mode being executed at the time point of determination by the instruction arrival determination unit and the next action mode to be executed after the action mode according to the determination result of the instruction arrival determination unit, and maintains the position of the slider at the time point of determination by the instruction arrival determination unit during the standby period.

2. The control device for a processing machine according to claim 1, wherein: When the instruction arrival determination unit determines that the deviation is greater than the pressure threshold, the slider position control unit sets the standby period between the action mode being executed at the determination time point of the instruction arrival determination unit and the action mode to be executed next to the action mode.

3. The control device for a processing machine according to claim 1 or 2, characterized in that: The command arrival determination unit determines whether the deviation is larger than the pressure threshold value at a time point a predetermined time before a time point when the currently executed operation mode is switched.

4. The control device for a processing machine according to claim 3, wherein: During the standby period set because the instruction arrival determination unit determines that the deviation is larger than the pressure threshold, when the instruction arrival determination unit determines that the deviation is below the pressure threshold, the slider position control unit ends the standby period to perform the position control of the slider corresponding to the next action mode to be executed.

5. The control device for a processing machine according to any one of claims 1 to 2 and 4, characterized in that: The processing machine processes the workpiece located on the plurality of die cushion pads by applying pressure through a single slider. The pressure command generating unit generates the pressure command for each of the plurality of die cushion pads. The pressure detection unit detects actual pressure applied to each of the plurality of die cushion pads. The die cushion speed control unit controls the speed of each of the plurality of die cushions based on a deviation between the pressure command and the actual pressure corresponding to the die cushion. The command arrival determination unit determines, for each of the plurality of die cushion pads, whether a deviation between the pressure command for the die cushion pad and the actual pressure is greater than the pressure threshold value at a time point predetermined before a time point at which the executed operation mode is switched. When it is determined that the deviation between the pressure command and the actual pressure of at least one of the mold cushion pads is greater than the pressure threshold, the slider position control unit sets the standby period between the action mode being executed at the determination time point of the command arrival determination unit and the action mode to be executed next to the action mode.

6. The control device for a processing machine according to claim 5, characterized in that: During the standby period, when the command arrival determination unit determines that the deviation between the pressure command and the actual pressure of at least one of the plurality of die cushion pads is equal to or less than the pressure threshold, the slider position control unit ends the standby period and performs position control of the slider corresponding to the next operation mode to be executed.

7. The control device for a processing machine according to claim 5, wherein: During the standby period, when the command arrival determination unit determines that the deviation between the pressure commands and the actual pressures of all the mold cushion pads is below the pressure threshold, the slider position control unit ends the standby period and performs the position control of the slider corresponding to the next action mode to be executed.

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