Abnormality detection apparatus for injection molding machine, injection molding machine, and method for detecting abnormality in injection molding machine

Abstract

This abnormality detection apparatus for an injection molding machine comprises a motor control unit for controlling a servo motor which operates an operation target via a power transmission unit, a data acquisition unit for acquiring load data, which is time-series physical quantity data that correlates with a load that acts on the servo motor, a data comparison unit for comparing the load data acquired by the data acquisition unit with reference data, which is time-series data that serves as a criterion for determining whether an abnormality has occurred in the power transmission unit and / or the servo motor, and an abnormality determination unit for determining, on the basis of the comparison result from the data comparison unit, whether an abnormality has occurred in the power transmission unit and / or the servo motor.

Description

Abnormal Detection Device for Injection Molding Machine, Injection Molding Machine, and Abnormal Detection Method for Injection Molding Machine

[0001] The present disclosure relates to an abnormal detection device for an injection molding machine, an injection molding machine, and an abnormal detection method for an injection molding machine.

[0002] Japanese Patent Application Laid-Open No. 2022-162619 discloses a wear detection device for an injection molding machine. This wear detection device detects wear of a connecting portion provided in a toggle mechanism by a laser distance sensor.

[0003] It is desirable to detect abnormalities occurring in an injection molding machine more favorably.

[0004] The present disclosure aims to solve the above-described problems.

[0005] A first aspect of the present disclosure includes a motor control unit that controls a servo motor that operates an operation target via a power transmission unit, and a predetermined operation condition that is a condition for causing the motor control unit to perform a predetermined operation on the operation target. A data acquisition unit that acquires load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when controlling the servo motor based on the above; reference data, which is time-series data serving as a criterion for determining whether an abnormality has occurred in at least one of the power transmission unit and the servo motor; and the load data acquired by the data acquisition unit. A data comparison unit that compares the above; and an abnormality determination unit that determines whether an abnormality has occurred in at least one of the power transmission unit and the servo motor based on the comparison result by the data comparison unit. It is an abnormal detection device for an injection molding machine.

[0006] A second aspect of the present disclosure is an injection molding machine including the abnormal detection device for an injection molding machine according to the first aspect.

[0007] A third aspect of the present disclosure is an abnormality detection method for an injection molding machine, comprising: a motor control step of controlling a servo motor that operates an object to be operated via a power transmission unit; a data acquisition step of acquiring load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when the servo motor is controlled in the motor control step based on predetermined operating conditions, which are conditions for causing the object to perform a predetermined operation; a data comparison step of comparing reference data, which is time-series data that serves as a criterion for determining whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor, with the load data acquired in the data acquisition step; and an abnormality determination step of determining whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor, based on the comparison result in the data comparison step.

[0008] According to this disclosure, abnormalities occurring in an injection molding machine can be detected effectively.

[0009] Figure 1 is a schematic diagram showing the configuration of an injection molding machine. Figure 2 is a block diagram showing the configuration of the control device. Figure 3 is a schematic diagram showing the inspection mode screen. Figure 4 is a flowchart of the inspection process. Figures 5A to 5C are graphs showing reference data and load data.

[0010] Injection molding machines are equipped with a drive mechanism. If any of the components of the drive mechanism malfunction (e.g., wear), it may cause a misalignment in the operation of the drive mechanism. To prevent damage to the drive mechanism, it is desirable to detect any malfunctions (wear, etc.) in the components of the drive mechanism as early as possible.

[0011] For example, one could consider using laser sensors to detect wear on parts. However, it is difficult to detect minute wear on parts with laser sensors. Moreover, installing sensors on injection molding machines would increase costs and require additional labor for installation.

[0012] The disclosure described below makes it possible to reliably detect abnormalities occurring in parts and other components installed in an injection molding machine without installing new sensors.

[0013] [1. Configuration of Injection Molding Machine 10] Figure 1 is a schematic diagram showing the configuration of the injection molding machine 10. The injection molding machine 10 comprises a base 12, a mold clamping device 14 installed on the base 12, and an injection device 16.

[0014] [1-1 Configuration of the Clamping Device 14] The clamping device 14 has a fixed platen 18, a rear platen 20, and four tie bars 22. The four tie bars 22 connect the fixed platen 18 and the rear platen 20. The four tie bars 22 are installed so that their axial directions are parallel to each other. A movable platen 24 is provided between the fixed platen 18 and the rear platen 20. The movable platen 24 is installed on the base 12 via a sliding part 26. The sliding part 26 is movable along a guide rail 28 provided on the base 12. As a result, the movable platen 24 is installed so as to be able to move back and forth in the axial direction of the tie bars 22 relative to the fixed platen 18.

[0015] A mold 30 is provided between the fixed platen 18 and the movable platen 24. The mold 30 consists of a fixed mold 32 and a movable mold 34. The fixed mold 32 is attached to the movable platen 24 side of the fixed platen 18, and the movable mold 34 is attached to the fixed platen 18 side of the movable platen 24.

[0016] A toggle link 36 is provided between the rear platen 20 and the movable platen 24. There are a total of four toggle links 36, two above and two below. The toggle link 36 includes a first link rod 38, a second link rod 40, a first toggle pin 42, a second toggle pin 44, and a third toggle pin 46. One end of the first link rod 38 is rotatably connected to the movable platen 24 via the first toggle pin 42. One end of the second link rod 40 is rotatably connected to the rear platen 20 via the second toggle pin 44. The other end of the first link rod 38 and the other end of the second link rod 40 are rotatably connected to each other via the third toggle pin 46.

[0017] The second link rod 40 is connected to the crosshead 50 via a cross link 48. The crosshead 50 has arms 52 (upper arm 52a, lower arm 52b) extending upward and downward, and the cross link 48 is connected to the tip of each arm 52. The rear platen 20 is provided with a guide rod (not shown). The guide rod (not shown) is positioned so that its axial direction is parallel to the axial direction of the tie bar 22. The crosshead 50 is positioned to move back and forth in a direction parallel to the axial direction of the tie bar 22, guided by the guide rod (not shown).

[0018] The mold clamping device 14 has a mold opening / closing mechanism 55 for opening and closing the mold 30. The mold opening / closing mechanism 55 comprises a servo motor 56, a drive pulley 58, a belt 60, a driven pulley 62, a ball screw 64, and a ball screw nut 66. The ball screw 64 is positioned so that its axial direction is parallel to the axial direction of the tie bar 22.

[0019] The drive pulley 58 is rotatably mounted integrally with the rotation shaft of the servo motor 56. The driven pulley 62 is rotatably mounted integrally with the ball screw 64. The belt 60 is stretched over the drive pulley 58 and the driven pulley 62, transmitting the rotational force of the drive pulley 58 to the driven pulley 62. The ball screw nut 66 is screwed onto the ball screw 64 and moves along the ball screw 64 as the ball screw 64 rotates. The ball screw nut 66 is fixed to the crosshead 50.

[0020] As the servo motor 56 rotates, rotational force is transmitted to the ball screw 64 via the drive pulley 58, belt 60, and driven pulley 62, causing the ball screw 64 to rotate. As the ball screw 64 rotates, the crosshead 50 moves along the guide rod (not shown) together with the ball screw nut 66. As the crosshead 50 moves, the movable platen 24 moves along the axial direction of the tie bar 22 via the cross link 48 and toggle link 36. When the movable platen 24 moves toward the fixed platen 18, the movable mold 34 comes into contact with the fixed mold 32, and the mold 30 closes. Conversely, when the movable platen 24 moves toward the rear platen 20, the movable mold 34 moves away from the fixed mold 32, and the mold 30 opens.

[0021] In this way, the movable platen 24, movable mold 34, etc. are operated by the rotational movement of the servo motor 56. That is, the objects of operation of the servo motor 56 are, for example, the movable platen 24, the movable mold 34, etc. The objects of operation of the servo motor 56 can be any part that is operated by the rotational movement of the servo motor 56. Among the various parts provided in the injection molding machine 10, the parts that transmit the power generated by the servo motor 56 to the movable mold 34 constitute the first power transmission unit. The servo motor 56 and the first power transmission unit constitute the first drive mechanism.

[0022] The clamping device 14 has an ejector mechanism 72 for removing molded products from the movable mold 34. The ejector mechanism 72 comprises a servo motor 74, a drive pulley 76, a belt 78, a driven pulley 80, a ball screw 82, a ball screw nut 84, an ejector plate 86, an ejector pin 88, and a guide rod 90. The ball screw 82 and the guide rod 90 are positioned so that their axial directions are parallel to the axial direction of the tie bar 22.

[0023] The drive pulley 76 is rotatably mounted integrally with the rotation shaft of the servo motor 74. The driven pulley 80 is rotatably mounted integrally with the ball screw 82. The belt 78 is stretched over the drive pulley 76 and the driven pulley 80, transmitting the rotational force of the drive pulley 76 to the driven pulley 80. The ball screw nut 84 is screwed onto the ball screw 82 and moves along the ball screw 82 as the ball screw 82 rotates. The ball screw nut 84 is fixed to the ejector plate 86 on which the ejector pins 88 are provided.

[0024] As the servo motor 74 rotates, rotational force is transmitted to the ball screw 82 via the drive pulley 76, belt 78, and driven pulley 80, causing the ball screw 82 to rotate. As the ball screw 82 rotates, the ejector plate 86 and ejector pin 88 move along the guide rod 90 together with the ball screw nut 84. When the ejector pin 88 moves toward the movable platen 24, the molded product is pushed out and removed from the movable mold 34.

[0025] In this way, the ejector plate 86, ejector pins 88, etc. are moved by the rotational movement of the servo motor 74. That is, the objects of operation of the servo motor 74 are, for example, the ejector plate 86, ejector pins 88, etc. The objects of operation of the servo motor 74 can be any part that is moved by the rotational movement of the servo motor 74. Among the various parts provided in the injection molding machine 10, the parts that transmit the power generated by the servo motor 74 to the ejector pins 88 constitute the second power transmission section. The servo motor 74 and the second power transmission section constitute the second drive mechanism.

[0026] [1-2 Configuration of Injection Molding Device 16] The injection molding device 16 includes a nozzle 92, a cylinder 94, a screw 96, a hopper 98, and a heater 100. Here, the nozzle 92, cylinder 94, and screw 96 are referred to as the injection unit 97. The nozzle 92 is provided at the tip of the cylinder 94. The cylinder 94 is a hollow member, and the screw 96 is inserted inside the cylinder 94. The cylinder 94 and the screw 96 extend in the opening and closing direction of the mold 30. The cylinder 94 is provided with a hopper 98. The hopper 98 is used to feed resin material into the cylinder 94. If the resin material fed from the hopper 98 is in pellet form, the heater 100 melts the pellet-shaped resin material.

[0027] The injection device 16 is mounted on the base 12 via an extruder base 102. The extruder base 102 is used to move the injection device 16 along the opening and closing direction of the mold 30. The injection device 16 has a screw drive mechanism 104 for rotating a screw 96 and an injection mechanism 105 for injecting resin material from a nozzle 92.

[0028] The screw drive mechanism 104 includes a servo motor 106, a drive pulley 108, a belt 110, and a driven pulley 112.

[0029] The drive pulley 108 is rotatably mounted integrally with the rotating shaft of the servo motor 106. The driven pulley 112 is rotatably mounted integrally with the screw 96. The belt 110 is stretched over the drive pulley 108 and the driven pulley 112, and transmits the rotational force of the drive pulley 108 to the driven pulley 112.

[0030] As the servo motor 106 rotates, rotational force is transmitted to the screw 96 via the drive pulley 108, belt 110, and driven pulley 112, causing the screw 96 to rotate. As the screw 96 rotates, the resin material is fed towards the nozzle 92.

[0031] In this way, the driven pulley 112, screw 96, etc. are operated by the rotational movement of the servo motor 106. That is, the objects of operation of the servo motor 106 are, for example, the driven pulley 112, screw 96, etc. The objects of operation of the servo motor 106 can be any part that is operated by the rotational movement of the servo motor 106. Among the various parts provided in the injection molding machine 10, the parts that transmit the power generated by the servo motor 106 to the screw 96 constitute the third power transmission section. The servo motor 106 and the third power transmission section constitute the third drive mechanism.

[0032] The injection mechanism 105 includes a servo motor 114, a drive pulley 116, a belt 118, a driven pulley 120, a ball screw 122, a ball screw nut 124, and a pusher plate 126. The ball screw 122 is positioned so that its axial direction is parallel to the axial direction of the screw 96.

[0033] The drive pulley 116 is rotatably mounted integrally with the rotation shaft of the servo motor 114. The driven pulley 120 is rotatably mounted integrally with the ball screw 122. The belt 118 is stretched over the drive pulley 116 and the driven pulley 120, transmitting the rotational force of the drive pulley 116 to the driven pulley 120. The ball screw nut 124 is screwed onto the ball screw 122 and moves along the ball screw 122 as the ball screw 122 rotates. The ball screw nut 124 is fixed to the pusher plate 126.

[0034] As the servo motor 114 rotates, rotational force is transmitted to the ball screw 122 via the drive pulley 116, belt 118, and driven pulley 120, causing the ball screw 122 to rotate. As the ball screw 122 rotates, the pusher plate 126 moves along the axial direction of the ball screw 122 together with the ball screw nut 124. The movement of the pusher plate 126 causes the screw 96 to move along the axial direction of the ball screw 122 within the cylinder 94. As the screw 96 moves toward the nozzle 92, the resin material stored at the tip of the screw 96 within the cylinder 94 is injected from the nozzle 92.

[0035] In this way, the pusher plate 126, screw 96, etc. are moved by the rotational movement of the servo motor 114. That is, the objects of operation of the servo motor 114 are, for example, the pusher plate 126, screw 96, etc. Note that the objects of operation of the servo motor 114 can be any part that is moved by the rotational movement of the servo motor 114. Among the various parts provided in the injection molding machine 10, the parts that transmit the power generated by the servo motor 114 to the screw 96 constitute the fourth power transmission unit. The servo motor 114 and the fourth power transmission unit constitute the fourth drive mechanism.

[0036] [2 Control device 130] The control device 130 that controls the operation of the injection molding machine 10 will be described using Figure 2. The control device 130 can operate the injection molding machine 10 in multiple operating modes. For example, the control device 130 can operate the injection molding machine 10 in molding mode and inspection mode. Molding mode is an operating mode for causing the object to perform a molding operation (movable platen 24, movable mold 34, ejector plate 86, ejector pin 88, driven pulley 112, pusher plate 126, screw 96, etc.). Inspection mode is an operating mode separate from molding mode for causing the object to perform a predetermined operation according to the inspection.

[0037] In this embodiment, the control device 130 has a function to detect abnormalities in the servo motor 56, the first power transmission unit (drive pulley 58, etc.), the servo motor 74, the second power transmission unit (drive pulley 76, etc.), the servo motor 106, the third power transmission unit (drive pulley 108, etc.), the servo motor 114, and the fourth power transmission unit (drive pulley 116, etc.). In other words, the control device 130 functions as an abnormality detection device.

[0038] In the following explanation, for the sake of clarity, the functions of the control device 130 that detect abnormalities in the servo motor 56 and the first power transmission unit will be described, while the functions that detect abnormalities in the servo motor 74, the second power transmission unit, the servo motor 106, the third power transmission unit, the servo motor 114, and the fourth power transmission unit will be omitted. In the following explanation, "servo motor 56," "first power transmission unit," "movable platen 24," and "movable mold 34" may be read as "servo motor 74," "second power transmission unit," "ejector plate 86," and "ejector pin 88." Similarly, in the following explanation, "servo motor 56," "first power transmission unit," "movable platen 24," and "movable mold 34" may be read as "servo motor 106," "third power transmission unit," "driven pulley 112," and "screw 96." Similarly, in the following description, "servo motor 56," "first power transmission unit," "movable platen 24," and "movable mold 34" may be replaced with "servo motor 114," "fourth power transmission unit," "pusher plate 126," and "screw 96."

[0039] Figure 2 is a block diagram showing the configuration of the control device 130. The control device 130 comprises an input unit 132, a display unit 134, a calculation unit 136, and a storage unit 138.

[0040] The input unit 132 is an input device that can be operated by the user. The input unit 132 inputs information corresponding to the user's operation to the calculation unit 136. The input unit 132 may be a hardware key or a software key. The input unit 132 includes, for example, a pointing device (mouse, touchpad, etc.), a keyboard, a control panel, etc.

[0041] The display unit 134 is a display device that displays information in a form that can be seen by the user. For example, the display unit 134 can display information in response to instructions from the calculation unit 136.

[0042] The input unit 132 and the display unit 134 may be touch panels that combine an input device and a display device. In the following description, unless otherwise specified, touch panels will be used as the input unit 132 and the display unit 134.

[0043] The calculation unit 136 can be constituted by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the calculation unit 136 can be constituted by a processing circuitry. At least a part of the calculation unit 136 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a part of the calculation unit 136 may be realized by an electronic circuit including discrete devices.

[0044] The calculation unit 136 includes a reception unit 140, a data acquisition unit 142, a data comparison unit 144, an abnormality determination unit 146, a motor control unit 148, an output control unit 150, and a display control unit 152. The reception unit 140, the data acquisition unit 142, the data comparison unit 144, the abnormality determination unit 146, the motor control unit 148, the output control unit 150, and the display control unit 152 can be realized by the program stored in the storage unit 138 being executed by the calculation unit 136.

[0045] The reception unit 140 receives the user's operation on the input unit 132. That is, the reception unit 140 acquires the information input by the user operating the input unit 132 from the input unit 132.

[0046] The data acquisition unit 142 acquires data from the storage unit 138 and sensors (not shown) etc. Also, the data acquisition unit 142 can also acquire data by performing calculations and the like. In the present embodiment, the data acquisition unit 142 acquires time-series data of a physical quantity correlated with the load acting on the servo motor 56. This time-series data is referred to as load data. Examples of the physical quantity correlated with the load include values such as the current supplied to the servo motor 56, the voltage applied to the servo motor 56, and the torque generated in the servo motor 56.

[0047] The data comparison unit 144 compares the reference data stored in the storage unit 138 with the load data acquired by the data acquisition unit 142. The reference data is time-series data serving as a reference for determining whether an abnormality has occurred in at least either the first power transmission unit or the servo motor 56.

[0048] The abnormality determination unit 146 determines whether an abnormality has occurred in at least either the first power transmission unit or the servo motor 56 based on the comparison result by the data comparison unit 144.

[0049] The output control unit 150 outputs information outside the arithmetic unit 136. For example, the output control unit 150 can output information to the storage unit 138 and the display unit 134. Also, the output control unit 150 can output information to a device (such as a communication terminal) outside the control device 130 via the communication module. Incidentally, when the output control unit 150 outputs information to the display unit 134, it functions as the display control unit 152. The display control unit 152 causes each piece of information to be displayed by controlling the display unit 134.

[0050] The storage unit 138 is a computer-readable storage medium. The storage unit 138 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory is, for example, a RAM (Random Access Memory) or the like. The non-volatile memory is, for example, a ROM (Read Only Memory), a flash memory, or the like. Data and the like are stored, for example, in the volatile memory. Programs, tables, maps, etc. are stored, for example, in the non-volatile memory. At least a part of the storage unit 138 may be provided in the above-described processor, integrated circuit, etc.

[0051] The non-volatile memory stores operating conditions corresponding to the molding mode for causing the operating object (movable platen 24, movable mold 34, etc.) to perform molding operations. The non-volatile memory also stores operating conditions corresponding to the inspection mode for causing the operating object to perform predetermined operations according to the inspection. The operating conditions corresponding to the inspection mode are called predetermined operating conditions. The predetermined operating conditions are different from the operating conditions for causing the operating object to perform molding operations. Note that the predetermined operating conditions may be set individually for each operating object that can be used in the injection molding machine 10.

[0052] The predetermined operation is one in which a significant difference in load data occurs between the case where an abnormality occurs in at least one of the first power transmission unit and the servo motor 56 and the case where no abnormality occurs in either the first power transmission unit or the servo motor 56. For example, the predetermined operation may be an operation in which the object to be operated (movable platen 24, movable mold 34, etc.) changes its direction of operation. In other words, the predetermined operation may be an operation in which the servo motor 56 changes its direction of rotation. Also, the predetermined operation may be an operation in which the object to be operated accelerates at or above a predetermined acceleration. In other words, the predetermined operation may be an operation in which the servo motor 56 rotates at a rotational acceleration of or above a predetermined value. By having the object to be operated perform the predetermined operation, a more significant difference can be made between the load data obtained when an abnormality occurs in at least one of the first power transmission unit and the servo motor 56 and the load data obtained when no abnormality occurs in either the first power transmission unit or the servo motor 56. This makes it easier to detect abnormalities occurring in the first power transmission unit and the servo motor 56.

[0053] Furthermore, one or more types of reference data are stored in the non-volatile memory. As described above, the reference data is time-series data that serves as a reference for determining whether or not an abnormality has occurred in at least one of the first power transmission unit and the servo motor 56. The reference data is time-series data acquired by the data acquisition unit 142 when the operating object (movable platen 24, movable mold 34, etc.) is made to perform a predetermined operation by the first power transmission unit and the servo motor 56, which are not experiencing any abnormalities. For example, the reference data may be load data acquired in past inspections in which it was determined that there were no abnormalities in the first power transmission unit and the servo motor 56.

[0054] The control device 130 outputs a control signal to the amplifier 162. The amplifier 162 supplies power to the servo motor 56 according to the control signal. As a result, the servo motor 56 rotates. The current sensor 154 detects the current supplied to the servo motor 56.

[0055] The control device 130 outputs a control signal to the amplifier 164. The amplifier 164 supplies power to the servo motor 74 according to the control signal. As a result, the servo motor 74 rotates. The current sensor 156 detects the current supplied to the servo motor 74.

[0056] The control device 130 outputs a control signal to the amplifier 166. The amplifier 166 supplies power to the servo motor 106 according to the control signal. As a result, the servo motor 106 rotates. The current sensor 158 detects the current supplied to the servo motor 106.

[0057] The control device 130 outputs a control signal to the amplifier 168. The amplifier 168 supplies power to the servo motor 114 according to the control signal. As a result, the servo motor 114 rotates. The current sensor 160 detects the current supplied to the servo motor 114.

[0058] [3 Inspection Mode Screen 170] Figure 3 is a schematic diagram showing the inspection mode screen 170. The user can select the inspection mode as the operating mode of the injection molding machine 10 by operating the input unit 132. When the user selects the inspection mode, the display control unit 152 displays the inspection mode screen 170 shown in Figure 3 on the display unit 134. The inspection mode screen 170 is divided into a setting display unit 172, a data count display unit 174, an identification information display unit 176, and an inspection result display unit 178.

[0059] The setting display unit 172 displays the current settings of the injection molding machine 10, item by item. For example, the setting display unit 172 displays the name of the mold 30 attached to the clamping device 14, the specifications (diameter, type) of the screw 96 attached to the injection device 16, the name of the resin used for molding, etc. Each piece of information displayed on the setting display unit 172 is stored in the storage unit 138. The user can edit the display contents of the setting display unit 172 by operating the input unit 132. The edited contents are stored in the storage unit 138.

[0060] The data count display unit 174 displays the number of load data entries acquired in past inspections. This number represents the number of load data entries acquired when the inspection was performed under the same conditions as the current settings. The "Clamping" column of the data count display unit 174 displays the number of load data entries related to the servo motor 56. The "Protrusion" column of the data count display unit 174 displays the number of load data entries related to the servo motor 74. The "Screw" column of the data count display unit 174 displays the number of load data entries related to the servo motor 106. The "Weighing" column of the data count display unit 174 displays the number of load data entries related to the servo motor 114. The information for each count displayed on the data count display unit 174 is stored in the storage unit 138.

[0061] The identification information display unit 176 displays selectable identification information for the reference data. The reference data here refers to load data acquired when the injection molding machine 10 was operated in the same state (same operating conditions) as the current setting in the past, and which was determined to be normal. The identification information is information used to identify each piece of reference data (load data). For example, the identification information is the date and time when the reference data was acquired. In the "Clamping" column of the identification information display unit 176, a list of the dates and times when reference data for the servo motor 56 was acquired is displayed in a pull-down menu. In the "Ejection" column of the identification information display unit 176, a list of the dates and times when reference data for the servo motor 74 was acquired is displayed in a pull-down menu. In the "Screw" column of the identification information display unit 176, a list of the dates and times when reference data for the servo motor 106 was acquired is displayed in a pull-down menu. In the "Weighing" column of the identification information display unit 176, a list of the dates and times when reference data for the servo motor 114 was acquired is displayed in a pull-down menu. Each piece of identification information displayed on the identification information display unit 176 is stored in the storage unit 138.

[0062] The inspection result display unit 178 displays multiple execution buttons 180, inspection result information, and inspection date information. Each execution button 180 is a software key that can be operated by the user. When the "clamping" execution button 180 is operated, the inspection process for the servo motor 56 and the first power transmission unit is executed. When the "extension" execution button 180 is operated, the inspection process for the servo motor 74 and the second power transmission unit is executed. When the "screw" execution button 180 is operated, the inspection process for the servo motor 106 and the third power transmission unit is executed. When the "weighing" execution button 180 is operated, the inspection process for the servo motor 114 and the fourth power transmission unit is executed. When the "all axes" execution button 180 is operated, the inspection process for all servo motors and all power transmission units is executed. Below each of the "clamping," "extension," "screw," and "weighing" execution buttons 180, the latest inspection result and inspection date and time are displayed. The latest inspection result and inspection date and time information are stored in the storage unit 138.

[0063] [4. Inspection Process] Figure 4 is a flowchart of the inspection process. The inspection process is performed by the calculation unit 136 when the inspection mode is set. When one of the five execution buttons 180 provided on the inspection mode screen 170 (Figure 3) is pressed by the user, the calculation unit 136 of the control device 130 executes the inspection process shown in Figure 4.

[0064] The following describes an inspection process using the servo motor 56 and the first power transmission unit involved in "clip clamping" as an example. The explanation of the inspection process using the servo motor 74, the second power transmission unit, the servo motor 106, the third power transmission unit, the servo motor 114, and the fourth power transmission unit as inspection targets will be omitted.

[0065] The user operates the input unit 132 to select the identification information of the reference data to be used in the inspection process from the list of identification information (date and time information) displayed in the "clamping" column of the identification information display unit 176 (Figure 3). After selecting the identification information, the user presses the "clamping" execution button 180 on the inspection result display unit 178. As a result, the calculation unit 136 executes an inspection process targeting the servo motor 56 and the first power transmission unit involved in "clamping".

[0066] In step S1, the data acquisition unit 142 acquires reference data corresponding to the identification information selected by the user from the storage unit 138.

[0067] In step S2, the data acquisition unit 142 acquires predetermined operating conditions from the storage unit 138 for causing the operating object (movable platen 24, movable mold 34, etc.) to perform a predetermined operation.

[0068] In step S3, the motor control unit 148 controls the operation of the servo motor 56 based on predetermined operating conditions acquired in step S2. For example, the motor control unit 148 may change the rotation direction of the servo motor 56. The motor control unit 148 may also rotate the servo motor 56 with a rotational acceleration of a predetermined value or higher. As a result, the object to be operated performs the predetermined operation.

[0069] In step S4, while the motor control unit 148 is controlling the operation of the servo motor 56, the data acquisition unit 142 acquires load data. For example, the current sensor 154 detects the current supplied from the amplifier 162 to the servo motor 56 and sends the detected information to the calculation unit 136. The data acquisition unit 142 acquires the information detected by the current sensor 154. As a result, the data acquisition unit 142 acquires the current value. Alternatively, the data acquisition unit 142 may calculate the torque value acting on the servo motor 56 based on the current value. The current value and torque value correspond to the load data acting on the servo motor 56. The output control unit 150 stores the acquired load data in the storage unit 138.

[0070] In step S5, the motor control unit 148 determines whether or not control of the servo motor 56 has ended. For example, the motor control unit 148 determines that control of the servo motor 56 has ended when the predetermined operation of the target is completed. If control of the servo motor 56 has ended (step S5: YES), the process proceeds to step S6. On the other hand, if control of the servo motor 56 has not ended (step S5: NO), the process returns to step S3.

[0071] When moving from step S5 to step S6, the data comparison unit 144 compares the reference data acquired in step S1 with the load data acquired in step S4. As described above, both the reference data and the load data are time-series data. For example, the data comparison unit 144 compares data values ​​with the same detection timing, using the point in time when the operating target started a predetermined operation as the reference point. That is, the data comparison unit 144 compares data values ​​with the same elapsed time from the reference point. By comparing the reference data and the load data, the data comparison unit 144 obtains the difference between the reference data and the load data. Since data values ​​with the same elapsed time from the reference point are compared, multiple difference amounts between the reference data and the load data are obtained.

[0072] The data comparison unit 144 may also extract data for a specific time period from the reference data and data for a specific time period from the load data, and compare the extracted reference data with the extracted load data. For example, the data comparison unit 144 may extract reference data and load data for a time period in which the acceleration of the operating object exceeds a predetermined acceleration, and compare the extracted reference data with the extracted load data. As another example, the data comparison unit 144 may extract reference data and load data for a predetermined time period that includes the timing when the operating object changes its direction of operation, and compare the extracted reference data with the extracted load data.

[0073] Figures 5A to 5C are graphs showing reference data and load data. Reference data is shown by a solid line. Load data is shown by a dashed line. The load data shown in Figures 5A to 5C is data obtained when an abnormality occurs in at least one of the first power transmission unit and the servo motor 56. In Figures 5A to 5C, the horizontal axis is time and the vertical axis is current value. Figure 5B is a graph of each data point in time period TA of Figure 5A, magnified with a different time axis scale. Figure 5C is a graph of each data point in time period TB of Figure 5A, magnified with a different time axis scale. As shown in Figure 5B, in time period TA, the reference data and load data substantially overlap. On the other hand, as shown in Figure 5C, in time period TB, there is a slight discrepancy between the reference data and the load data. Thus, there are time periods in which a difference is likely to occur between the reference data and the load data when an abnormality occurs in at least one of the first power transmission unit and the servo motor 56. By comparing the reference data and load data in such time periods, the comparison process can be performed efficiently.

[0074] In step S7, the data comparison unit 144 determines whether there is a difference between the reference data and the load data. More specifically, it determines whether there is a significant difference between the reference data and the load data. The data comparison unit 144 determines that there is a difference between the reference data and the load data if the maximum difference amount, which is the largest difference amount among the multiple difference amounts obtained in step S6, is equal to or greater than a predetermined maximum difference amount threshold. The data comparison unit 144 determines that there is no difference between the reference data and the load data if the maximum difference amount among the multiple difference amounts obtained in step S6 is not equal to or greater than a predetermined maximum difference amount threshold. The data comparison unit 144 may also determine whether there is a difference between the reference data and the load data as follows: That is, the data comparison unit 144 may determine that there is a difference between the reference data and the load data if the average difference amount, which is the average of the multiple difference amounts obtained in step S6, is equal to or greater than a predetermined average difference amount threshold. Alternatively, the data comparison unit 144 may determine that there is no difference between the reference data and the load data if the average difference amount, which is the average of the multiple difference amounts obtained in step S6, is not equal to a predetermined average difference amount threshold. If the data comparison unit 144 determines that there is a difference between the reference data and the load data (step S7: YES), the process proceeds to step S8. On the other hand, if the data comparison unit 144 determines that there is no difference between the reference data and the load data (step S7: NO), the process proceeds to step S9.

[0075] When the system moves from step S7 to step S8, the abnormality determination unit 146 determines that there is an abnormality in at least one of the first power transmission unit and the servo motor 56.

[0076] When the process moves from step S7 to step S9, the abnormality determination unit 146 determines that there is no abnormality in either the first power transmission unit or the servo motor 56. In this case, the load data stored in the storage unit 138 in step S4 can be used as reference data in subsequent inspections.

[0077] When the system moves from step S8 or step S9 to step S10, the display control unit 152 (output control unit 150) displays the inspection results on the display unit 134. If there is no abnormality in either the first power transmission unit or the servo motor 56, the display control unit 152 displays the word "OK" in the inspection result display field below the "clamping" execution button 180. If there is an abnormality in at least one of the first power transmission unit or the servo motor 56, the display control unit 152 displays the word "NG" in the inspection result display field below the "clamping" execution button 180. The output control unit 150 also stores the inspection results in the storage unit 138, linked to the acquired load data.

[0078] [5 Other Embodiments] The data comparison unit 144 may perform other comparisons. For example, the data comparison unit 144 may compare the time it takes for the load data to reach a second predetermined value from a first predetermined value (referred to as the first time) with the time it takes for the reference data to reach a second predetermined value from a first predetermined value (referred to as the second time). In this case, the data comparison unit 144 may determine that there is a difference if the difference between the first time and the second time is greater than or equal to a predetermined time difference, and determine that there is no difference if the difference between the first time and the second time is not greater than or equal to a predetermined time difference.

[0079] [6 Effects] If an abnormality occurs in at least one of the first power transmission unit and the servo motor 56, it will affect the load data of the servo motor 56. Therefore, by comparing the reference data with the load data, it is possible to determine whether or not an abnormality has occurred in at least one of the first power transmission unit and the servo motor 56. The same applies to the second power transmission unit and the servo motor 74, the third power transmission unit and the servo motor 106, and the fourth power transmission unit and the servo motor 114. Accordingly, according to the above embodiment, abnormalities occurring in parts etc. provided in the injection molding machine 10 can be detected early. In other words, according to the above embodiment, abnormalities occurring in the injection molding machine 10 can be detected well.

[0080] [7. Addendum] The following addendum is further disclosed with respect to the above embodiment.

[0081] (Note 1) The abnormality detection device (130) of the injection molding machine (10) of the present disclosure includes: a motor control unit (148) that controls servo motors (56, 74, 106, 114) that operate an object to be operated (24, 34, 86, 88, 96, 112, 126, etc.) via a power transmission unit; a data acquisition unit (142) that acquires load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when the motor control unit controls the servo motor based on predetermined operating conditions, which are conditions for causing the object to perform a predetermined operation; a data comparison unit (144) that compares reference data, which is time-series data that serves as a criterion for determining whether an abnormality has occurred in at least one of the power transmission unit and the servo motor, with the load data acquired by the data acquisition unit; and an abnormality determination unit (146) that determines whether an abnormality has occurred in at least one of the power transmission unit and the servo motor based on the comparison result by the data comparison unit.

[0082] (Note 2) The abnormality detection device for the injection molding machine described in Note 1 may be provided with an output control unit (150) that outputs the determination result from the abnormality determination unit.

[0083] (Note 3) In the abnormality detection device for an injection molding machine described in Note 1 or 2, the injection molding machine can be operated in an inspection mode for checking whether or not an abnormality has occurred in the injection molding machine, in addition to operation in the operating mode for performing injection molding, and the motor control unit may control the servo motor based on the predetermined operating conditions when the injection molding machine is operated in the inspection mode.

[0084] (Note 4) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 3, the predetermined operating conditions may be different from the operating conditions for causing the target to perform the molding operation.

[0085] (Note 5) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 4, the predetermined operation may be an operation in which a significant difference occurs in the load data between the case in which an abnormality occurs in at least one of the power transmission unit and the servo motor and the case in which no abnormality occurs in either the power transmission unit or the servo motor.

[0086] (Note 6) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 5, the reference data may be time-series data acquired by the data acquisition unit when the target of operation is made to perform the predetermined operation by the power transmission unit and the servo motor, which are not experiencing any abnormalities.

[0087] (Note 7) An abnormality detection device for an injection molding machine described in any one of Notes 1 to 6, comprising a display control unit (152) capable of selectively displaying identification information for identifying each of the plurality of reference data on a display unit (134), wherein the data comparison unit compares the reference data corresponding to the identification information selected by the user from among the plurality of identification information selectively displayed on the display unit with the load data acquired by the data acquisition unit.

[0088] (Note 8) In the abnormality detection device for the injection molding machine described in Note 7, the reference data may be the load data obtained in the past when the injection molding machine was operating in the same state as the current setting, and which was determined to be normal.

[0089] (Note 9) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 8, the predetermined operation may be an operation in which the object of operation changes its direction of operation.

[0090] (Note 10) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 8, the predetermined operation may be an operation in which the object to be operated is accelerated to a predetermined acceleration or higher.

[0091] (Note 11) In the abnormality detection device for an injection molding machine described in any one of Notes 1 to 10, the data comparison unit may compare the time it takes for the load data to reach a second predetermined value from a first predetermined value with the time it takes for the reference data to reach a second predetermined value from the first predetermined value.

[0092] (Note 12) In the abnormality detection device for injection molding machines described in Note 9, the data comparison unit may compare the load data with the reference data during a time period that includes the timing at which the operating object changes its operating direction.

[0093] (Note 13) In the abnormality detection device for injection molding machines described in Note 10, the data comparison unit may compare the load data and the reference data during the time period in which the acceleration of the operating object exceeds the predetermined acceleration.

[0094] (Note 14) The injection molding machine of this disclosure is equipped with an abnormality detection device for an injection molding machine as described in any one of Notes 1 to 13.

[0095] (Note 15) The abnormality detection method for an injection molding machine according to the present disclosure comprises: a motor control step of controlling a servo motor that operates an object to be operated via a power transmission unit; a data acquisition step of acquiring load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when the servo motor is controlled in the motor control step based on predetermined operating conditions, which are conditions for causing the object to perform a predetermined operation; a data comparison step of comparing reference data, which is time-series data that serves as a criterion for determining whether an abnormality has occurred in at least one of the power transmission unit and the servo motor, with the load data acquired in the data acquisition step; and an abnormality determination step of determining whether an abnormality has occurred in at least one of the power transmission unit and the servo motor based on the comparison result in the data comparison step.

[0096] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0097] 10...Injection molding machine 24...Movable platen (operating object) 34...Movable mold (operating object) 56, 74, 106, 114...Servo motor 86...Ejector plate (operating object) 88...Ejector pin (operating object) 96...Screw (operating object) 112...Driven pulley (operating object) 126...Pusher plate (operating object) 130...Control device (anomaly detection device) 134...Display unit 142...Data acquisition unit 144...Data comparison unit 146...Anomaly determination unit 148...Motor control unit 150...Output control unit 152...Display control unit

Claims

1. An abnormality detection device for an injection molding machine, comprising: a motor control unit that controls a servo motor that operates an object via a power transmission unit; a data acquisition unit that acquires load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when the motor control unit controls the servo motor based on predetermined operating conditions, which are conditions for causing the object to perform a predetermined operation; a data comparison unit that compares reference data, which is time-series data that serves as a criterion for determining whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor, with the load data acquired by the data acquisition unit; and an abnormality determination unit that determines whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor based on the comparison result by the data comparison unit.

2. An abnormality detection device for an injection molding machine according to claim 1, comprising an output control unit that outputs a determination result by the abnormality determination unit.

3. An abnormality detection device for an injection molding machine according to claim 1 or 2, wherein the injection molding machine is capable of operating in an inspection mode for checking whether or not an abnormality has occurred in the injection molding machine, in addition to operating in an operating mode for performing injection molding, and the motor control unit controls the servo motor based on predetermined operating conditions when the injection molding machine is operated in the inspection mode.

4. An abnormality detection device for an injection molding machine according to any one of claims 1 to 3, wherein the predetermined operating conditions are different from the operating conditions for causing the target to perform a molding operation.

5. An abnormality detection device for an injection molding machine according to any one of claims 1 to 4, wherein the predetermined operation is an operation in which a significant difference occurs in the load data when an abnormality occurs in at least one of the power transmission unit and the servo motor, and when no abnormality occurs in either the power transmission unit or the servo motor.

6. An abnormality detection device for an injection molding machine according to any one of claims 1 to 5, wherein the reference data is time-series data acquired by the data acquisition unit when the target of operation is made to perform the predetermined operation by the power transmission unit and the servo motor, in which no abnormality has occurred.

7. An abnormality detection device for an injection molding machine according to any one of claims 1 to 6, comprising a display control unit capable of selectively displaying identification information for identifying each of a plurality of reference data on a display unit, wherein the data comparison unit compares the reference data corresponding to the identification information selected by the user from among the plurality of identification information selectively displayed on the display unit with the load data acquired by the data acquisition unit.

8. An abnormality detection device for an injection molding machine according to claim 7, wherein the reference data is the load data obtained in the past when the injection molding machine was operating in the same state as the current setting, and which was determined to be normal.

9. An abnormality detection device for an injection molding machine according to any one of claims 1 to 8, wherein the predetermined operation is an operation in which the object of operation changes its direction of operation.

10. An abnormality detection device for an injection molding machine according to any one of claims 1 to 8, wherein the predetermined operation is an operation in which the object to be operated is accelerated at or above a predetermined acceleration.

11. An abnormality detection device for an injection molding machine according to any one of claims 1 to 10, wherein the data comparison unit compares the time it takes for the load data to reach a second predetermined value from a first predetermined value with the time it takes for the reference data to reach a second predetermined value from the first predetermined value.

12. An abnormality detection device for an injection molding machine according to claim 9, wherein the data comparison unit compares the load data with the reference data during a time period that includes the timing at which the operating object changes the direction of operation.

13. An abnormality detection device for an injection molding machine according to claim 10, wherein the data comparison unit compares the load data with the reference data during the time period in which the acceleration of the operating object exceeds the predetermined acceleration.

14. An injection molding machine equipped with an abnormality detection device for injection molding machines according to any one of claims 1 to 13.

15. An abnormality detection method for an injection molding machine, comprising: a motor control step of controlling a servo motor that operates an object to be operated via a power transmission unit; a data acquisition step of acquiring load data, which is time-series data of a physical quantity correlated with the load acting on the servo motor, when the servo motor is controlled in the motor control step based on predetermined operating conditions, which are conditions for causing the object to perform a predetermined operation; a data comparison step of comparing reference data, which is time-series data that serves as a criterion for determining whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor, with the load data acquired in the data acquisition step; and an abnormality determination step of determining whether or not an abnormality has occurred in at least one of the power transmission unit and the servo motor, based on the comparison result in the data comparison step.

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