Press machine and abnormality detection method for press machine

Abstract

To provide a press machine or the like capable of detecting abnormality of a die in a plurality of processes.SOLUTION: The press machine includes a detector that detects a load value when press working is performed on a work material, a storage that stores the load value for one cycle of pressing detected by the detector in association with identification information of a die attached to the press machine at the time of detection of the load value, a calculator that obtains an eccentric load for each predetermined press angle based on the stored load value for one cycle and generates distribution data of the eccentric load for each die, a determiner that determines abnormality based on the eccentric load for each predetermined press angle obtained based on the load value for one cycle detected by the detector and the distribution data of the eccentric load corresponding to the die attached to the press machine at the time of detection of the load value, and a notifier that notifies the abnormality based on a determination result of the determiner.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a press machine and a method for detecting an abnormality in a press machine. [Background technology]

[0002] Conventionally, a method has been known in which the amount of eccentricity (eccentric position) is calculated from the left and right load values ​​when the total load value, which is the sum of the left and right load values ​​in one press cycle, reaches its peak value, and an abnormality is detected when the eccentric load exceeds the range of an allowable eccentric load diagram (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-209887 Summary of the Invention [Problem to be solved by the invention]

[0004] The conventional method described above cannot detect an abnormality based on an eccentric load when the total load value does not reach a peak value. For example, in progressive press processing or transfer press processing, the processing content differs for each stage, so the loads of each stage do not necessarily occur at the same time. The conventional method can detect an abnormality in the processing (process) of the stage where the peak load occurs, but cannot detect an abnormality in the processing of other stages.

[0005] Furthermore, conventional methods are functions for protecting the press machine. However, in addition to protecting the press, press machine users also need to manage the condition of the molds and the precision of the formed products, and if mold abnormalities or poor product precision occur, they need to detect them early and take measures. Because mold abnormalities and poor product precision mainly occur within the range of the allowable eccentric load diagram, it is difficult to detect mold abnormalities or poor product precision using conventional methods.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a press machine and a method for detecting an abnormality in a press machine that are capable of detecting abnormalities in a die at multiple processes. [Means for solving the problem]

[0007] (1) A press machine according to the present invention is a press machine characterized by including: a detection unit that detects load values ​​when press processing is performed on a workpiece; a memory unit that stores the load values ​​for one press cycle detected by the detection unit in association with identification information of a die attached to the press machine at the time the load values ​​were detected; a calculation unit that determines the eccentric load for each predetermined press angle based on the stored load values ​​for one cycle and generates distribution data of the eccentric load for each die; a judgment unit that determines an abnormality based on the eccentric load for each predetermined press angle determined based on the load values ​​for one press cycle detected by the detection unit and the distribution data of the eccentric load corresponding to the die attached to the press machine at the time the load values ​​were detected; and a notification unit that notifies of an abnormality based on the judgment result of the judgment unit.

[0008] Furthermore, the method for detecting an abnormality in a press machine according to the present invention includes a detection step of detecting a load value when a workpiece is pressed, a storage step of storing the load values ​​for one cycle of the press detected in the detection step in association with identification information of a die attached to the press machine at the time the load values ​​were detected, and a calculation step of determining an eccentric load for each predetermined press angle based on the stored load values ​​for one cycle and generating distribution data of the eccentric load for each die. This method for detecting an abnormality in a press machine includes: a determination step of determining an abnormality based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle of the press detected in the detection step, and distribution data of the eccentric load corresponding to the die attached to the press machine at the time the load values ​​are detected; and a notification step of notifying the abnormality based on the determination result of the determination step.

[0009] According to the present invention, the detected load values ​​for one cycle are stored in association with identification information of the die attached to the press machine at the time of detection, the eccentric load for each press angle is calculated based on the stored load values ​​for one cycle to generate eccentric load distribution data for each die, and an abnormality is determined based on the eccentric load for each press angle calculated based on the detected load values ​​for one cycle and the eccentric load distribution data corresponding to the die attached to the press machine at the time the load values ​​were detected, thereby making it possible to detect abnormalities in the die in multiple processes.

[0010] (2) In the press machine according to the present invention, the calculation unit may average the eccentric load distribution data to generate average data, and the determination unit may determine an abnormality based on the eccentric load for each predetermined press angle calculated based on the load value for one cycle detected by the detection unit and the average data corresponding to the die attached to the press machine at the time the load value was detected.

[0011] In the method for detecting an abnormality in a press machine according to the present invention, in the calculating step, average data may be generated by averaging the eccentric load distribution data, and in the determining step, an abnormality may be determined based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle detected by the detection unit and the average data corresponding to a die attached to the press machine at the time the load values ​​were detected.

[0012] (3) In the press machine according to the present invention, the calculation unit extracts eccentric load data for each press angle from the eccentric load distribution data, and generates data for determining an identification boundary indicating a normal range of the eccentric load for each press angle using machine learning from the extracted eccentric load data, and the determination unit may determine an abnormality based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle detected by the detection unit and the data for determining an identification boundary indicating a normal range of the eccentric load for each press angle corresponding to a die attached to the press machine at the time the load values ​​were detected.

[0013] In the method for detecting an abnormality in a press machine according to the present invention, the calculating step may extract eccentric load data for each press angle from the eccentric load distribution data, and generate data for determining a discrimination boundary that indicates a normal range of the eccentric load for each press angle using machine learning from the extracted eccentric load data, and the determining step may determine an abnormality based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle detected by the detection unit and the data for determining a discrimination boundary that indicates a normal range of the eccentric load for each press angle that corresponds to a die attached to the press machine at the time the load values ​​are detected. [Brief explanation of the drawings]

[0014] [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] FIG. 2 is a diagram showing an example of a load sensor. [Figure 3] 10 is a flowchart showing the flow of a process for generating distribution data of eccentric loads according to the first embodiment. [Figure 4] FIG. 10 is a diagram showing an example of stored load values. [Figure 5] FIG. 10 is a diagram showing an example of an eccentric load for each predetermined crank angle calculated from a load value of one shot. [Figure 6] FIG. 10 is a diagram showing an example of distribution data of eccentric loads corresponding to a selected die number. [Figure 7] FIG. 10 is a diagram showing an example of average data of eccentric loads. [Figure 8] 10 is a flowchart showing a process for generating distribution data of eccentric loads according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing an example of distribution data of eccentric load and data showing a normal range obtained by machine learning. [Figure 10] 1 is a flowchart showing the flow of a process for detecting an abnormality according to a first embodiment. [Figure 11] FIG. 10 is a diagram showing an example of average data and detected data of an eccentric load. [Figure 12] 10 is a flowchart showing the flow of a process for detecting an abnormality according to a second embodiment. [Figure 13]FIG. 10 is a diagram showing an example of a total load value and a left-right load difference corresponding to a crank angle. [Figure 14] FIG. 10 is a diagram showing an example of the timing at which a load is generated in progressive press working. [Figure 15] FIG. 10 is a diagram showing an example of a three-dimensional display of eccentric loads for each predetermined crank angle calculated from the load value of one shot. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0016] 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 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.

[0017] 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 the crankshaft 15 are supported by appropriate bearings (not shown). The crankshaft 15 and the 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 stationary bolster 18. In this example, the press machine 1 is a two-point drive press machine in which the crankshaft 15 and the slide 17 are connected by two connecting rods 16 that also function as suspensions. An upper die 20 is attached to the slide 17, and a lower die 21 is attached to the bolster 18.

[0018] The press machine 1 is equipped with a right load sensor 30 and a left load sensor 31 for detecting the load value during each press cycle when pressing the workpiece. As shown in FIG. 2 , the right load sensor 30 is a strain gauge attached to a right column 40 (right side frame) of the press machine 1, and the left load sensor 31 is a strain gauge attached to a left column 41 (left side frame) of the press machine 1. When determining eccentric loads in the front-to-rear direction as well as the left-to-right direction of the press machine, it is desirable to provide load sensors on each of the four columns (not shown): the front right, rear right, front left, and rear left. Note that the right load sensor 30 and the left load sensor 31 may also be pressure sensors provided in hydraulic chambers formed within the slide 17. When pressure sensors are used in a four-point drive press machine, pressure sensors are provided in each of the four hydraulic chambers: the front right, rear right, front left, and rear left. The output data (voltage signals of the strain gauges or pressure sensors) of the right load sensor 30 and the left load sensor 31 are input to the control device 100.

[0019] The control device 100 includes a press control unit 101, a detection unit 102, a memory unit 103, a calculation unit 104, a determination unit 105, and an alarm unit 106. 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 display control unit 107, a user interface 110, and a display 120, and an independent device for detecting a load, which is composed of the detection unit 102, the memory unit 103, the calculation unit 104, the determination unit 105, the alarm unit 106, the user interface 110, and the display 120. In this case, the output data of the right load sensor 30 and the left load sensor 31 are directly input to the device for detecting the load. Furthermore, press machine operating information, such as crank angle information, is input from the device for controlling the press machine to the device for detecting the load, as necessary.

[0020] The detection unit 102 receives data output from the right load sensor 30 and data output from the left load sensor 31 for each press cycle, converts the received data based on calibration data stored in the memory unit 103, and detects it as load values ​​(right load value and left load value) during press working. The calibration data indicates the relationship between voltage signals and load values, and is measured in advance using a load cell or the like and stored in the memory unit 103.

[0021] The memory unit 103 stores the load value for one press cycle detected by the detection unit 102 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 value was detected.

[0022] The calculation unit 104 calculates the eccentric load for each predetermined press angle based on the load values ​​for one press cycle stored in the memory unit 103, and generates eccentric load distribution data for each die. The press angle is the angle corresponding to the position of the slide 17 during one press cycle and refers to the angle of a main shaft, such as a crankshaft or eccentric shaft. Because a crankshaft is used in this embodiment, the press angle will be referred to as the "crank angle" hereinafter. To calculate the eccentric load for a given crank angle, the position of the load center acting on the press machine 1 is calculated based on the load values ​​(right load value and left load value) at that crank angle. The calculated load center position is then calculated as the amount of eccentricity from the center of the press machine 1, and the eccentric load for that crank angle (the combination of the total load value of the right load value and the left load value and the amount of eccentricity) is calculated. Here, the load center refers to the center of gravity of the load. The center of the press machine 1 refers to the center position of the slide 17 on a plane perpendicular to the direction in which the slide 17 moves (up and down). Furthermore, the calculation unit 104 may generate average data (average data for each mold) by averaging the distribution data of the eccentric load.

[0023] The calculation unit 104 may further extract eccentric load data for each crank angle from the eccentric load distribution data, and generate normal range data of the eccentric load for each crank angle from the extracted eccentric load data using machine learning such as one-class SVM (support vector machine). The normal range data is data generated for determining an identification boundary indicating the normal range, and is data that constitutes a line or a plane for determining the normal range.

[0024] The judgment unit 105 judges whether an abnormality has occurred based on the eccentric load for each crank angle calculated by the calculation unit 104 based on the load value for one press cycle detected by the detection unit 102, and the distribution data (or average data) of the eccentric load corresponding to the mold attached to the slide 17 and bolster 18 of the press machine 1 at the time the load value was detected.

[0025] The notification unit 106 notifies of an abnormality based on the determination result of the determination unit 105. For example, when the determination unit 105 determines that an abnormality has occurred, the notification unit 106 outputs information to that effect 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 interface 110 may 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. 3 is a flowchart showing a process flow for generating distribution data of eccentric loads in the first embodiment.

[0029] The processing of steps S10 to S13 is processing for storing load values. The load values ​​are stored when a test run (die trial) is performed after dies are attached to the press machine 1. First, the detection unit 102 receives data output from the right load sensor 30 and data output from the left load sensor 31, converts the received data based on the calibration data stored in the memory unit 103, and detects them as load values ​​(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 memory unit 103 stores the detected load values ​​for one cycle (waveform data of the right load and waveform data of the left load) 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 (step S12). FIG. 4 shows an example of the load values ​​to be stored. As shown in FIG. 4, a load waveform WR for one cycle detected based on data from the right load sensor 30 and a load waveform WL for one cycle detected based on data from the left load sensor 31 are stored as load values ​​in association with the die number. The load waveform for one cycle is, for example, a load value for each degree in the crank angle range of 0 to 359 degrees. Next, the control device 100 determines whether or not to end the storage of the load values ​​(step S13), and if storage is to continue (N in step S13), proceeds to step S10, and thereafter stores a load value for each press cycle.

[0030] The processes of steps S14 to S18 are processes for generating eccentric load distribution data. First, the control device 100 selects a die number based on a user's operation on the user interface 110 (step S14). Next, the calculation unit 104 extracts load values ​​corresponding to the selected die number from the stored load value data (step S15). Then, the calculation unit 104 calculates the amount of eccentricity for each predetermined crank angle (for example, for each 1-degree crank angle in the range of 0 to 359 degrees) from each extracted load value (load value for one cycle) to obtain the eccentric load for each predetermined crank angle, and generates eccentric load distribution data corresponding to the selected die number (step S16). The amount of eccentricity (eccentric position) at any crank angle can be calculated from the balance of moments based on the left and right load values ​​at that crank angle and the distance between the right load sensor 30 and the left load sensor 31 (distance dc shown in FIG. 2). The amount of eccentricity is positive when the right load is greater than the left load, negative when the left load is greater than the right load, and the absolute value increases as the difference between the left and right loads increases. The eccentric load at any crank angle is a set of data consisting of the sum of the left and right load values ​​at that crank angle (total load value) and the amount of eccentricity calculated from the left and right load values. When pressure sensors installed in hydraulic chambers formed in the slide 17 are used as the right load sensor 30 and the left load sensor 31, the amount of eccentricity can be calculated based on the left and right load values ​​and the distance between the two connecting rods 16 (point distance, distance dp shown in FIG. 2).

[0031] Figure 5 shows an example of the eccentric load for each predetermined crank angle calculated from the load value for one shot. The graphs shown in Figures 5 and 6 are plotted with the eccentric position (unit: mm) on the horizontal axis and the total load value (unit: kN) on the vertical axis, with the eccentric load for each crank angle degree. Each solid dot in the figure represents one eccentric load datum, and eccentric loads for adjacent crank angles are connected by a line. Figure 6 shows an example of eccentric load distribution data corresponding to a selected die number, with the eccentric load for each predetermined crank angle calculated from the load values ​​for multiple shots (here, three shots) of the same die extracted.

[0032] Next, the calculation unit 104 averages the generated eccentric load distribution data and stores the generated data as average data corresponding to the selected die number in the storage unit 103 (step S17). Fig. 7 shows average data generated by averaging the eccentric loads at the same crank angle in the eccentric load distribution data shown in Fig. 6.

[0033] Next, the control device 100 determines whether to continue processing (generate eccentric load distribution data and average data or normal range data corresponding to another mold number) (step S18), and if processing is to be continued (Y in step S18), proceeds to step S14.

[0034] 8 is a flowchart showing the flow of a process for generating distribution data of eccentric loads in Example 2. As in Example 1, the load values ​​are stored when a die is attached to the press machine 1 and a trial run is performed. Also, steps S20 to S26 are the same as in Example 1, and therefore a description thereof will be omitted.

[0035] The calculation unit 104 extracts eccentric load data for each predetermined crank angle from the eccentric load distribution data, and generates data for determining an identification boundary indicating a normal range of eccentric load for each predetermined crank angle from the extracted eccentric load data using machine learning, and stores the data in the storage unit 103 as data indicating the normal range of eccentric load for each predetermined crank angle corresponding to the selected die number (step S27). Fig. 9 shows an example of the normal range determined using machine learning from multiple eccentric load data for a certain crank angle in the eccentric load distribution data, as well as data within the normal range and data outside the normal range (abnormal data).

[0036] 10 is a flowchart showing the flow of the process for detecting an abnormality in Example 1. The detection of an abnormality is carried out during normal press operation.

[0037] First, the detection unit 102 receives data output from the right load sensor 30 and data output from the left load sensor 31, converts the received data based on the calibration data stored in the memory unit 103, and detects it as a load value (step S30). Next, the control device 100 determines whether one press cycle has ended based on information about the current crank angle (step S31). If one cycle has not ended (N in step S31), the control device 100 proceeds to step S30 and continues detecting load values. If one cycle has ended (Y in step S31), the calculation unit 104 calculates the amount of eccentricity for each predetermined crank angle from the detected load values ​​for one cycle (waveform data of the right load and waveform data of the left load) to determine the eccentric load for each predetermined crank angle (step S32).

[0038] Next, the determination unit 105 acquires the average data corresponding to the die number of the die attached to the slide 17 and bolster 18 of the press machine 1 when the load value was detected in step S30 from among the average data for each die stored in the memory unit 103, calculates the distance between the eccentric load for each predetermined crank angle calculated in step S32 and the acquired average data (step S33), and determines whether the calculated distance is within a predetermined allowable range (step S34). If the calculated distance exceeds the allowable range (N in step S34), the notification unit 106 issues an abnormality notification ( (Step S35). For example, for the eccentric loads for each predetermined crank angle in the average data and the eccentric loads for each predetermined crank angle calculated in step S32, the distance between the eccentric loads at the same crank angle (the distance on the x-y plane with the eccentric amount as the x-axis and the total load value as the y-axis) may be calculated, and eccentric loads for which the calculated distance exceeds a predetermined threshold may be considered abnormal points. If the number of abnormal points is equal to or greater than a predetermined number, it may be determined that the allowable range has been exceeded. Alternatively, if the total or average value of the calculated distances exceeds a predetermined threshold, it may be determined that the allowable range has been exceeded. FIG. 11 shows an example of the average data AV and the detected data DT (the eccentric loads for each predetermined crank angle calculated in step S32) when an abnormality is detected (the distance exceeds the allowable range). Note that when calculating the distance between the average data AV and the detected data DT, only data on eccentric loads whose total load value is equal to or greater than a predetermined value may be used. In the example shown in FIG. 11, only the distance between the average data AV and the detected data DT for eccentric loads whose total load value is equal to or greater than 50 kN is calculated (eccentric loads whose total load value is less than 50 kN are excluded). Also, the distance between the average data AV and the detection data DT may be found using only the eccentric load data within a predetermined crank angle range (for example, a range of 180±n degrees).

[0039] Next, the control device 100 determines whether or not to continue the process of detecting abnormalities (step S36), and if the process is to be continued (Y in step S36), it proceeds to step S30, and thereafter detects abnormalities based on the eccentric load calculated for each press cycle.

[0040] 12 is a flowchart showing the flow of the process for detecting an abnormality in Example 2. As in Example 1, the detection of an abnormality is performed during normal press operation. Furthermore, steps S40 to S42 are the same as in Example 1, and therefore a description thereof will be omitted.

[0041] The determination unit 105 acquires, as normal range data, data indicating the normal range of the eccentric load for each predetermined crank angle that corresponds to the die number of the die attached to the slide 17 and bolster 18 of the press machine 1 at the time of detecting the load value in step S40, from the data indicating the normal range of the eccentric load for each predetermined crank angle stored in the memory unit 103, calculates the distance (position) of the eccentric load for each predetermined crank angle calculated in step S42 relative to the normal range of the eccentric load for each predetermined crank angle that was calculated (step S43), and determines whether the calculated distance (position) is within the normal range (step S44). If the distance (position) is outside the normal range (N in step S44), the notification unit 106 issues a notification of an abnormality (step S45).

[0042] Next, the control device 100 determines whether or not to continue the process of detecting an abnormality (step S46), and if the process is to be continued (Y in step S46), it proceeds to step S40, and thereafter detects an abnormality based on the eccentric load calculated for each press cycle and data indicating the normal range of the eccentric load for each specified crank angle.

[0043] According to this embodiment, the load values ​​for one press cycle detected by the detection unit 102 are stored in advance 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 the load values ​​were detected, the eccentric load for each crank angle is calculated based on the stored load values ​​for one press cycle to generate distribution data (average data) of the eccentric load for each die, and an abnormality is determined based on the eccentric load for each crank angle calculated based on the load values ​​for one press cycle detected by the detection unit 102 during press operation and the eccentric load distribution data corresponding to the dies attached to the slide 17 and bolster 18 of the press machine 1 at the time the load values ​​were detected, thereby making it possible to detect abnormalities in the dies at multiple processes.

[0044] In the prior art, an abnormality is detected by calculating the eccentric load from the left and right load values ​​when the total load value reaches its peak value, so it is not possible to detect an abnormality based on the eccentric load when the total load value does not reach its peak value. Figure 13 shows the total load value LT (the sum of the right load value LR and the left load value LL) and the left and right load difference LD (the difference between the right load value LR and the left load value LL) corresponding to the crank angle. 13 shows an example of the eccentric load ELp when the total load value LT reaches its peak value, and the eccentric load ELd when the left-right load difference LD is at its maximum. In the example of FIG. 13, the eccentric load ELd when the left-right load difference LD is at its maximum exceeds the range of the allowable eccentric load diagram AD, but the eccentric load ELp when the total load value LT reaches its peak value is within the range of the allowable eccentric load diagram AD, so that an abnormality cannot be detected with conventional technology. On the other hand, in this embodiment, it is possible to detect an abnormality if the distance between the eccentric load ELd and the eccentric load at the crank angle corresponding to the average data (or the distance of the eccentric load ELd from the normal range of the eccentric load at the corresponding crank angle) is sufficiently large.

[0045] Furthermore, when multiple processes (stages) are performed using a single press machine, such as progressive press working or transfer press working, the processing content differs for each stage, so loads do not necessarily occur at the same time for each stage. Figure 14 shows an example of the timing at which loads occur in progressive press working. In this example, processing is performed in four stages ST1 to ST4, and as the slide 17 descends toward the bottom dead center, loads are generated in the following order: stage ST1, stage ST4, stage ST2, and stage ST3. Conventional technology can detect abnormalities in processing at the stage where a peak load occurs, but cannot detect abnormalities in processing at other stages. In contrast, this embodiment calculates the eccentric load for each specified crank angle and performs an abnormality determination, making it possible to detect abnormalities in processes other than the process where the peak load occurs.

[0046] Furthermore, the distribution data of the eccentric load acting on the press machine may be displayed in a three-dimensional graph. FIG. 15 shows an example of a three-dimensional graph. In this graph, the horizontal axis represents the eccentric position (unit: mm) in the left-right direction (X axis) and the front-back direction (Y axis) from the center of the press machine, and the vertical axis (Z axis) represents the total load value (unit: kN). The mountain-shaped curve represents the allowable eccentric load diagram AD. Compared to a two-dimensional display, a three-dimensional display makes it easier for the operator to visually recognize the difference between the current detection data DT and the average data AV (distribution under normal conditions), not shown, and enables earlier detection of signs of trouble.

[0047] Patent Document 1 discloses a calculation method for creating an allowable load diagram (corresponding to AD in Figure 13) for a two-point drive press machine, a method that has long been well-known among those skilled in the art. The allowable eccentric load diagram created by this calculation method is limited only by the point capacity and does not take into account the effects of slide tilt. Slide tilt occurs due to the amount of rotational moment applied to the press machine due to the eccentric load and the press machine structure that receives that rotational moment. Therefore, even when a press machine is operated with a load within the allowable eccentric load limit limited only by the point capacity, there is a concern that slide tilt may cause problems such as deterioration in product accuracy, seizure of the slide guide, damage to the mold, and even damage to the press machine frame and points. To avoid such problems, each press manufacturer creates a composite allowable load diagram based on the point capacity limit, taking into account a safety factor and limitations on the amount of slide tilt, and provides it to users. Furthermore, in a two-point drive press machine, when an eccentric load acts on the slide in the fore-and-aft direction, the slide behaves structurally in the same way as a single-point drive press machine, rotating and tilting due to a rotational moment with the point-to-slide connection as the fulcrum. The magnitude of the tilt depends on the amount of rotational moment and the structure of the press machine, such as the slide guide that receives the rotational moment. For this reason, we have created a composite allowable load diagram for the allowable eccentric load in the fore-and-aft direction of a two-point drive press machine, just like for the left-and-right direction, based on the point capacity limits, taking into account safety factors and limits on the amount of slide tilt, and provide this diagram to users.

[0048] 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]

[0049] 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...right load sensor, 31...left load sensor, 40...right column (right side frame), 41...left column (left side frame), 100...control device, 101...press control unit, 102...detection unit, 103...storage unit, 104...calculation unit, 105...determination unit, 106...notification unit, 107...display control unit, 110...user interface, 120...display

Claims

1. a detection unit that detects a load value when press working is performed on a workpiece; 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 the eccentric load for each predetermined press angle based on the stored load values ​​for one cycle and generates distribution data of the eccentric load for each die; a determination unit that determines an abnormality based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one press cycle detected by the detection unit and on distribution data of the eccentric load corresponding to the die attached to the press machine at the time the load values ​​were detected; and a notification unit that notifies of an abnormality based on a determination result of the determination unit.

2. In claim 1, The calculation unit Averaging the distribution data of the eccentric load to generate average data; The determination unit a press machine, characterized in that an abnormality is determined based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle detected by the detection unit, and on the average data corresponding to the die attached to the press machine at the time the load values ​​were detected.

3. In claim 1, The calculation unit generating normal range data for determining a normal range of the eccentric load for each press angle using machine learning from the eccentric load distribution data; The determination unit a press machine, characterized in that an abnormality is determined based on an eccentric load for each predetermined press angle calculated based on the load values ​​for one cycle detected by the detection unit, and on normal range data of the eccentric load for each press angle corresponding to a die attached to the press machine at the time the load values ​​are detected.

4. a detection step of detecting a load value when performing press processing on a workpiece; 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 determining the eccentric load for each predetermined press angle based on the stored load values ​​for one cycle and generating distribution data of the eccentric load for each die; a determination step of determining whether there is an abnormality based on the eccentric load for each predetermined press angle calculated based on the load values ​​for one press cycle detected in the detection step and on distribution data of the eccentric load corresponding to the die attached to the press machine at the time of detection of the load values; a notifying step of notifying an abnormality based on a determination result of the determining step.

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