Press machine and die state monitoring method

Abstract

To provide a press machine or the like capable of monitoring a state of a die for performing punching by using a sensor provided in the press machine.SOLUTION: The press machine includes a detection unit that detects a load value when punching a workpiece based on a signal output from a sensor provided in the press machine, a storage unit that stores the load value for one press cycle detected by the detection unit in association with identification information of a die attached to the press machine when the load value is detected, a calculation unit that obtains a total load, which is a sum of loads from contact of an upper die with the workpiece to completion of punching, based on the load value for one press cycle, and an information generation unit that generates and outputs information on a state of the die based on the total load obtained based on the load value for one press cycle detected by the detection unit and the total load obtained based on the load value for one press cycle stored in association with the die attached to the press machine when the load value is detected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a press machine and a die state monitoring method. [Background technology]

[0002] In dies used in punching processes, it is necessary to periodically perform maintenance (polishing) of the punches and dies. Conventionally, a method has been known in which a sensor (such as a strain gauge) is used to measure the stress and strain applied to the die during punching to determine the die's lifespan (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-87224 [Patent Document 2] Japanese Patent Application Publication No. 2019-10658 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional method, sensors must be installed in all molds, and if they are not installed, it is not possible to determine the lifespan of the mold. In addition, in the conventional method, it is necessary to take into account positional errors when removing and installing sensors, which is cumbersome.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a press machine and a die condition monitoring method that are capable of monitoring the condition of a die that performs punching processing using a sensor provided in the press machine. [Means for solving the problem]

[0006] (1) The press machine according to the present invention is a detection unit that detects a load value when punching a workpiece based on a signal output from a sensor provided in the press machine; a storage unit that stores the load value for one cycle of the press detected by the detection unit in association with identification information of the die attached to the press machine at the time the load value was detected; a calculation unit that calculates a total load, which is the sum of the loads from when the upper die contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed, or until the load value decreases to a predetermined threshold value, based on the load value for one cycle; and an information generating unit that generates and outputs information relating to the state of the die based on the total load calculated based on the load value for one cycle of the press detected by the detection unit and the total load calculated based on the load value for one cycle that is stored in correspondence with the die attached to the press machine at the time the load value is detected.

[0007] The mold state monitoring method according to the present invention further comprises: a detection step of detecting a load value when punching a workpiece based on a signal output from a sensor provided in the press machine; a storage step of storing the load value for one cycle of the press detected in the detection step in association with identification information of the die attached to the press machine at the time the load value was detected; a calculation step of calculating a total load, which is the sum of the loads from when the upper die contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed, or until the load value decreases to a predetermined threshold value, based on the load value for one cycle; The load value obtained based on the load value for one cycle of the press detected in the detecting step. and an information generating step of generating and outputting information relating to the state of the die based on a total load and the total load calculated based on the load values ​​for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0008] According to the present invention, the load value during punching is detected based on the signal from a sensor provided in the press machine, and information regarding the state of the die is generated and output based on the sum of the loads (total load) from when the upper die contacts the workpiece until a breakthrough phenomenon occurs after punching is completed, or until the load value drops to a predetermined threshold value, thereby making it possible to monitor the state of the die without attaching a sensor to the die.

[0009] (2) In the press machine according to the present invention, The information generation unit Information regarding the state of the die may be generated based on the difference between the total load calculated based on the load value for one cycle of the press detected by the detection unit and the total load calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0010] In addition, in the mold state monitoring method according to the present invention, In the information generating step, Information regarding the state of the die may be generated based on the difference between the total load calculated based on the load value for one cycle of the press detected by the detection unit and the total load calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0011] (3) In the press machine according to the present invention, The calculation unit Based on the load value for one cycle, a processing time is calculated, which is the time from when the upper die contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed, or until the load value decreases to a predetermined threshold value. The information generation unit Information regarding the state of the die may be generated based on the processing time calculated based on the load value for one cycle of the press detected by the detection unit and the processing time calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0012] In addition, in the mold state monitoring method according to the present invention, In the calculation step, Based on the load value for one cycle, a processing time is calculated, which is the time from when the upper die contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed, or until the load value decreases to a predetermined threshold value. In the information generating step, Information regarding the state of the die may be generated based on the processing time calculated based on the load value for one cycle of the press detected by the detection unit and the processing time calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0013] According to the present invention, the load value during punching is detected based on the signal of the sensor provided in the press machine, and the time from when the upper die contacts the workpiece to when the breakthrough phenomenon occurs after punching is completed, or when the load value decreases to a predetermined threshold value (processing time) is calculated. By generating and outputting information about the mold condition based on this, it is possible to monitor the mold condition without attaching sensors to the mold.

[0014] (4) In the press machine according to the present invention, The information generation unit Information regarding the state of the die may be generated based on the difference between the processing time calculated based on the load value for one cycle of the press detected by the detection unit and the processing time calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected.

[0015] In addition, in the mold state monitoring method according to the present invention, In the information generating step, Information regarding the state of the die may be generated based on the difference between the processing time calculated based on the load value for one cycle of the press detected by the detection unit and the processing time calculated based on the load value for one cycle stored in association with the die attached to the press machine at the time the load value was detected. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a press machine according to an embodiment of the present invention. [Figure 2] 10 is a flowchart showing the flow of a process for storing a load value. [Figure 3] FIG. 10 is a diagram showing an example of load values ​​for one press cycle. [Figure 4] 10 is a flowchart showing the flow of a process for monitoring the state of a mold. [Figure 5] FIG. 1 is a diagram for explaining three phases of a load waveform during punching. [Figure 6] FIG. 6 is a diagram showing data obtained by extracting only the second phase from the load waveform shown in FIG. 5 . [Figure 7] FIG. 10 is a diagram for explaining the total load and processing time. [Figure 8] 10A and 10B are diagrams showing a load waveform stored immediately after maintenance is performed and a load waveform stored immediately before maintenance is performed. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] FIG. 1 is a diagram showing an example of the configuration of a press machine (servo press) according to this embodiment. The press machine 1 converts the rotation of a servo motor 10 into up-and-down reciprocating motion (reciprocating linear motion, lifting motion) of a slide 17 using an eccentric mechanism that converts rotational motion into linear motion, and performs press processing (punching) on ​​a workpiece using the up-and-down reciprocating motion of the slide 17. The press machine 1 includes a servo motor 10, an encoder 11, a drive shaft 12, a drive gear 13, a main gear 14, a crankshaft 15, a connecting rod 16, a slide 17, a bolster 18, a control device 100, a user interface 110 (operation unit), and a display 120 (display unit). The press machine is not limited to a servo press, and may be, for example, a mechanical press using a flywheel.

[0019] A drive shaft 12 is connected to the rotating shaft of the servo motor 10, and a drive gear 13 is connected to the drive shaft 12. A main gear 14 is engaged with the drive gear 13, and a crankshaft 15 is connected to the main gear 14, and a connecting rod 16 is connected to the crankshaft 15. Rotating shafts such as the drive shaft 12 and crankshaft 15 are supported by bearings (not shown) provided as appropriate. The crankshaft 15 and connecting rod 16 form an eccentric mechanism. This eccentric mechanism allows a slide 17 connected to the connecting rod 16 to move up and down relative to a bolster 18 on the stationary side. Here, the press machine 1 is a two-stage press in which the crankshaft 15 and slide 17 are connected by two connecting rods 16 that also function as suspensions. This is a point-driven press machine. An upper die 20 (upper die, punch) is attached to the slide 17, and a lower die 21 (lower die, die) is attached to the bolster 18.

[0020] The press machine 1 is equipped with a load sensor 30 for detecting a load value when punching a workpiece. The load sensor 30 is a strain gauge attached to the right column (right side frame) or left column (left side frame) of the press machine 1. Note that a pressure sensor provided in a hydraulic chamber formed in the slide 17 may also be used as the load sensor 30. A signal output from the load sensor 30 (a voltage signal from the strain gauge or pressure sensor) is input to the control device 100.

[0021] The control device 100 includes a press control unit 101, a detection unit 102, a memory unit 103, a calculation unit 104, and an information generation unit 105. The control device 100 may be divided into an independent device for controlling the press machine, which is composed of the press control unit 101, a user interface 110, and a display 120, and an independent device for detecting a load, which is composed of the detection unit 102, a memory unit 103, a calculation unit 104, an information generation unit 105, a user interface 110, and a display 120. In this case, the output signal of the load sensor 30 is directly input to the device for detecting the load. Furthermore, press machine operating information, such as crank angle information, is input to the device for detecting the load from the device for controlling the press machine, as necessary.

[0022] The detection unit 102 receives the signal output from the load sensor 30, converts the received signal based on the calibration data stored in the memory unit 103, and detects it as a load value during punching. The calibration data indicates the relationship between the voltage signal and the load value, and is measured in advance using a load cell or the like and stored in the memory unit 103.

[0023] The memory unit 103 stores the load values ​​for one press cycle detected by the detection unit 102 (time series information of the load values ​​for one press cycle) in association with the identification information (die number) of the dies (upper die 20, lower die 21) attached to the slide 17 and bolster 18 of the press machine 1 at the time the load values ​​were detected, and the SPM (Strokes Per Minute) at the time the load values ​​were detected.

[0024] The calculation unit 104 calculates the total load, which is the sum of the loads from when the upper die 20 contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed or until the load value drops to a predetermined threshold, based on the load value for one press cycle. The calculation unit 104 also calculates the processing time, which is the time from when the upper die 20 contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed or until the load value drops to a predetermined threshold.

[0025] The information generation unit 105 generates information about the state of the die based on the total load calculated by the calculation unit 104 based on the load value for one press cycle detected by the detection unit 102 and the total load calculated by the calculation unit 104 based on the load value for one press cycle stored in association with the die attached to the press machine at the time the load value was detected and the SPM at the time the load value was detected, and outputs the information about the state of the die to the display 120. The information generation unit 105 also generates information about the state of the die based on the processing time calculated by the calculation unit 104 based on the load value for one press cycle detected by the detection unit 102 and the processing time calculated by the calculation unit 104 based on the load value for one press cycle stored in association with the die attached to the press machine at the time the load value was detected and the SPM at the time the load value was detected, and outputs the information about the state of the die to the display 120.

[0026] The user interface 110 is a known input means (for example, a mouse, a trackball, a keyboard, etc.) that can be operated on the display 120. The user interface 110 may also be provided integrally with the display 120. In this case, the input means is displayed on the display 120.

[0027] The display 120 is a liquid crystal display (LCD (Liquid Crystal Display)). Other known display devices (for example, organic EL (Electro Luminescence)) may also be used as the display 120. A touch panel display may also be used as the display 120. Known touch panels such as resistive, capacitive, surface capacitive, and projected capacitive touch panels may be used as the touch panel. If the display is a touch panel type, input operations can be performed by directly touching the display 120 with a finger or a pen.

[0028] FIG. 2 is a flowchart showing the process flow for storing load values. First, the detection unit 102 receives a signal output from the load sensor 30 and converts the received signal based on the calibration data stored in the storage unit 103 to detect a load value (step S10). Next, the control device 100 determines whether one press cycle has ended based on information about the current crank angle (step S11). If one cycle has not ended (N in step S11), the control device 100 proceeds to step S10 and continues detecting load values. If one cycle has ended (Y in step S11), the storage unit 103 stores the detected load values ​​(load waveform data) for one press cycle in association with the die numbers of the dies attached to the slide 17 and bolster 18 of the press machine 1 at the time of detection, the SPM at the time of detection, and time information (time stamp) (step S12). FIG. 3 is a graph showing the load values ​​(load waveform) for one press cycle, with the horizontal axis representing time (unit: ms) and the vertical axis representing load values ​​(unit: kN).

[0029] Next, the control device 100 determines whether or not the user has input mold maintenance information (the mold number of the mold on which maintenance (polishing) was performed, and the date of maintenance) to the user interface 110 (step S13), and if the maintenance information has been input (Y in step S13), the storage unit 103 stores the input maintenance information (step S14). Next, the control device 100 determines whether or not to end storage of the load values ​​(step S15), and if storage is to continue (N in step S15), the process proceeds to step S10, and thereafter, the load values ​​for one press cycle are stored for each press cycle.

[0030] FIG. 4 is a flowchart showing the process flow for monitoring the die state (generating and outputting information about the die state). First, the detection unit 102 receives a signal output from the load sensor 30 and converts the received signal based on the calibration data stored in the memory unit 103 to detect a load value (step S20). Next, the control device 100 determines whether one press cycle has ended based on information about the current crank angle (step S21). If one cycle has not ended (N in step S21), the control device 100 proceeds to step S20 and continues detecting load values. If one cycle has ended (Y in step S21), the calculation unit 104 calculates, from the detected load values ​​for one press cycle, a total load L, which is the sum of the loads from when the upper die 20 contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed or until the load value decreases to a predetermined threshold, and a processing time T, which is the time from when the upper die 20 contacts the workpiece material until a breakthrough phenomenon occurs after punching is completed or until the load value decreases to a predetermined threshold (step S22).

[0031] As shown in Figure 5, the load value (load waveform) for one press cycle during punching can be roughly divided into three phases (regions R1 to R3). Region R1, which is the first phase, is the pre-processing region from when the slide 17 starts to descend until the upper die 20 comes into contact with the workpiece material. Region R2, which is the second phase, is the processing region from when the upper die 20 comes into contact with the workpiece material until the breakthrough phenomenon occurs after punching is completed. Region R3, which is the third phase, is the region where a vibration waveform due to the breakthrough phenomenon appears. The breakthrough phenomenon is a phenomenon in which the pressurizing force generated by punching causes the flapping of the press machine. This is a phenomenon in which the energy of elastic deformation generated in the frame, etc., is released immediately after material separation occurs, and the upper die 20 is momentarily pushed into the lower die 21 due to the reaction force as it tries to return to its original shape. The data required to grasp the state of the die is data on region R2, which is the processing region. Figure 6 shows data extracted from region R2 alone from the load waveform in Figure 5. In step S22, as shown in Figure 7, the total load L of region R2 (the sum of the loads from when the upper die 20 contacts the workpiece material to when the breakthrough phenomenon occurs after punching is completed, equivalent to the area of ​​the region shown by diagonal lines in the figure) and processing time T (the time from when the upper die 20 contacts the workpiece material to when the breakthrough phenomenon occurs after punching is completed) are calculated from the data on region R2. In the time series of load values ​​for one press cycle shown in FIG. 5, the point at which the load value exceeds a predetermined threshold (e.g., 10 kN) can be identified as the boundary between regions R1 and R2 (the point at which the upper die 20 contacts the workpiece), and the point at which the load value changes from a positive value to a negative value can be identified as the boundary between regions R2 and R3 (the point at which the breakthrough phenomenon occurs after punching is completed). Furthermore, if a pressure sensor installed in a hydraulic chamber formed in the slide 17 is used as the load sensor 30, the breakthrough phenomenon will not appear in the load waveform, and the load waveform will be similar to that shown in FIG. 6 from the beginning. In this case, the point at which the load value returns to a predetermined threshold (e.g., 10 kN) can be identified as the boundary between regions R2 and R3 (the point at which punching is completed).

[0032] Next, the calculation unit 104 acquires the load value for one press cycle that is associated with the die number of the die attached to the slide 17 and bolster 18 of the press machine 1 at the time of detection of the load value in step S20, and that is associated with the SPM at the time of detection, from among the load values ​​for one press cycle stored in the memory unit 103 in association with the die number and the SPM, and calculates the total load L and the processing time T from the acquired load value for one press cycle (step S23). Here, by referring to the maintenance information stored in the memory unit 103, the calculation unit 104 acquires the load value for one press cycle that was stored immediately after maintenance of the die was performed, and calculates the total load L (hereinafter referred to as La) and the processing time T (hereinafter referred to as Ta) from the load value, and acquires the load value for one press cycle that was stored immediately before maintenance of the die was performed, and calculates the total load L (hereinafter referred to as Lb) and the processing time T (hereinafter referred to as Tb) from the load value. For example, if the mold number of the mold installed at the time of load detection in step S20 is "5" and the SPM at that time is "100", of the load values ​​for one press cycle stored in association with the mold number "5" and the SPM "100", the load value stored immediately before maintenance was performed on the mold with mold number "5" and the load value stored immediately after the maintenance was performed are obtained.

[0033] Next, the information generating unit 105 generates information IL about the state of the mold based on the total load L (hereinafter referred to as Ld) calculated in step S22 and the total loads La and Lb calculated in step S23, and generates information IT about the state of the mold based on the processing time T (hereinafter referred to as Td) calculated in step S22 and the processing times Ta and Tb calculated in step S23, and outputs the generated information IL and IT to the display 120 (step S24). IL and IT are calculated by the following equations.

[0034] IL = (Lb - Ld) / (Lb - La) × 100 IT = (Tb - Td) / (Tb - Ta) × 100 IL is the ratio of the difference between the total load Lb immediately before maintenance and the total load Ld calculated in step S22 to the difference between the total load Lb immediately before maintenance and the total load La immediately after maintenance, and is a value indicating the remaining life (unit: %) of the mold based on the total load. Also, IT is the ratio of the difference between the machining time Tb immediately before maintenance and the machining time Td calculated in step S22 to the difference between the machining time Tb immediately before maintenance and the machining time Ta immediately after maintenance, and is a value indicating the remaining life (unit: %) of the mold based on the machining time.

[0035] Figure 8 shows the load values ​​for one press cycle stored immediately after maintenance (solid line) and the load values ​​for one press cycle stored immediately before maintenance (dashed line). As shown in Figure 8, as die wear progresses, the total load L and processing time T increase, with the total load La and processing time Ta being smallest immediately after maintenance and the total load Lb and processing time Tb being largest immediately before maintenance. If the total load Ld and processing time Td calculated in step S22 are close to the total load La and processing time Ta immediately after maintenance (the difference between Lb and Ld and the difference between Tb and Td are large), the calculated remaining lifespan (IL, IT) of the die will be close to 100%, indicating that die wear has not progressed and that it is not yet time to perform maintenance. On the other hand, if the total load Ld and machining time Td calculated in step S22 are close to the total load Lb and machining time Tb immediately before maintenance was performed (the difference between Lb and Ld, and the difference between Tb and Td are small), the calculated remaining lifespan (IL, IT) of the mold will be close to 0%, indicating that the mold is wearing out and the time to perform maintenance is approaching.

[0036] In step S23, only the load value for one press cycle stored immediately before maintenance is obtained to determine only the total load Lb and processing time Tb, and in step S24, the difference between the total load Lb and the total load Ld may be set as the remaining life of the die based on the total load (IL=Lb-Ld), and the difference between the processing time Tb and the processing time Td may be set as the remaining life of the die based on the processing time (IT=Tb-Td).In addition, in step S24, it may be determined whether either IL or IT (or both) is below a predetermined threshold, and if it is below the predetermined threshold, information to that effect (information that the time to perform die maintenance is approaching) may be output.

[0037] Next, the control device 100 determines whether or not to continue the process of monitoring the state of the die (step S25), and if the process is to be continued (Y in step S25), it proceeds to step S20, and thereafter generates and outputs information IL and IT regarding the state of the die based on the total load Ld and processing time Td calculated for each press cycle.

[0038] According to this embodiment, the load value during punching is detected based on a signal from the load sensor 30 provided in the press machine 1, and the total load Ld and processing time Td from when the upper die 20 contacts the workpiece until a breakthrough phenomenon occurs after punching is completed or until the load value drops to a predetermined threshold are calculated, and information IL and IT about the state of the die are generated and output based on the difference between the total load Lb and processing time Tb immediately before maintenance is performed, thereby making it possible to monitor the state of the die without attaching a sensor to the die.

[0039] Although the embodiments of the present invention have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present invention. [Explanation of symbols]

[0040] 1...press machine, 10...servo motor, 11...encoder, 12...drive shaft, 13...drive gear, 14...main gear, 15...crankshaft, 16...connecting rod, 17...slide, 18...bolster, 20...upper die, 21...lower die, 30...load sensor, 100...control device, 101...press control unit, 102...detection unit, 103...storage unit, 104...calculation unit, 105...information generation unit, 110...user interface, 120...display

Claims

1. a detection unit that detects a load value when punching a workpiece based on a signal output from a sensor provided in the press machine; a storage unit that stores the load value for one cycle of the press detected by the detection unit in association with identification information of the die attached to the press machine at the time the load value was detected; a calculation unit that calculates a total load, which is the sum of the loads from when the upper die contacts the workpiece to when punching is completed, based on the load value for one cycle; and an information generating unit that generates and outputs information relating to a state of the die, based on the total load calculated based on the load values ​​for one cycle of the press detected by the detection unit and the total load calculated based on the load values ​​for one cycle that are stored in correspondence with the die attached to the press machine at the time the load values ​​are detected.

2. In claim 1, The information generation unit a press machine, characterized in that information relating to a state of the die is generated based on a difference between the total load calculated based on the load values ​​for one cycle of the press detected by the detection unit and the total load calculated based on the load values ​​for one cycle stored in correspondence with the die attached to the press machine at the time the load values ​​were detected.

3. In claim 1, The calculation unit A processing time is calculated based on the load value for one cycle, which is the time from when the upper die contacts the workpiece material to when punching is completed. The information generation unit a press machine, characterized in that information about a state of the die is generated based on the processing time calculated based on the load values ​​for one cycle of the press detected by the detection unit, and the processing time calculated based on the load values ​​for one cycle stored in correspondence with the die attached to the press machine at the time the load values ​​were detected.

4. In claim 3, The information generation unit a press machine, characterized in that information about a state of the die is generated based on a difference between the processing time calculated based on the load values ​​for one cycle of the press detected by the detection unit and the processing time calculated based on the load values ​​for one cycle stored in correspondence with the die attached to the press machine at the time the load values ​​were detected.

5. a detection step of detecting a load value when punching a workpiece based on a signal output from a sensor provided in the press machine; a storage step of storing the load value for one cycle of the press detected in the detection step in association with identification information of the die attached to the press machine at the time the load value was detected; a calculation step of calculating a total load, which is the sum of the loads from when the upper die contacts the workpiece material to when punching is completed, based on the load value for one cycle; and an information generating step of generating and outputting information relating to the state of the die, based on the total load calculated based on the load values ​​for one cycle of the press detected in the detection step and the total load calculated based on the load values ​​for one cycle stored in correspondence with the die attached to the press machine at the time of load value detection.

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