Injection molding machine monitoring device

Abstract

This injection molding machine monitoring device comprises: an acquisition unit that acquires, from a detection unit provided to a link of a toggle mechanism, an amount of change that has occurred in the link, on the basis of a detected value during a decompression step; and a determination unit that determines whether the amount of change acquired by the acquisition unit exceeds a prescribed threshold.

Description

Technical Field

[0001] The present invention relates to a monitoring device for an injection molding machine.

Background Art

[0002] In a normal injection molding machine, a molded product is formed by filling a molding material into a mold device. The mold device is composed of a fixed mold and a movable mold. The movable mold is attached to a movable platen, and the mold support device is arranged to be movable in the mold opening and closing direction. A toggle mechanism for moving the movable platen in the mold opening and closing direction is composed of a plurality of link members. As the movable platen moves in the mold opening and closing direction, the plurality of link members also move, so the connecting portions of the link members wear out.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology described in Patent Document 1, wear is detected based on the displacement amount between the position of the member in the initial state before wear and the position of the member at the time of mold clamping. On the other hand, in recent years, there has been a desire to detect wear of the above link members in a simple manner.

[0005] One aspect of the present invention provides a technique for easily detecting wear by performing detection based on the amount of change generated in a link member during pressure release that reduces the mold clamping force.

Means for Solving the Problems

[0006] A monitoring device for an injection molding machine according to one aspect of the present invention includes an acquisition unit that acquires the amount of change that occurs in the link member based on the detection value in the depressurization process of a detection unit provided on the link member of the toggle mechanism, and the amount of change acquired by the acquisition unit Depending on the circumstances, wear may be occurring in the link member. No / No determination unit and ,of Yes The amount of change that occurs in the link member and is acquired by the acquisition unit is either the amount of strain that occurs in the link member or the acceleration that occurs in the link member. . [Effects of the Invention]

[0007] According to one aspect of the present invention, wear of a link member can be easily detected by performing detection based on the amount of change that occurs in the link member. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the state of the injection molding machine upon completion of mold opening according to the first embodiment. [Figure 2] Figure 2 shows the state of the injection molding machine during mold clamping according to the first embodiment. [Figure 3] Figure 3 is a diagram showing the configuration of the toggle mechanism included in the injection molding machine according to the first embodiment. [Figure 4] Figure 4 is a diagram showing an example of the configuration of a control device according to the first embodiment. [Figure 5] Figure 5 shows the forces generated within the toggle mechanism during the depressurization process according to the first embodiment. [Figure 6] Figure 6 is a perspective view showing the shape of the second link according to the first embodiment. [Figure 7] Figure 7 is a front view showing the shape of the second link according to the first embodiment. [Figure 8] Figure 8 illustrates the change in the amount of strain acquired by the acquisition unit during the depressurization process of the first embodiment. [Figure 9] Figure 9 is a flowchart showing the procedure for determining whether or not wear has occurred by the control device according to the first embodiment. [Figure 10] Figure 10 illustrates the change in acceleration acquired by the acquisition unit during the depressurization process of the first embodiment. [Figure 11] Figure 11 is a flowchart showing the procedure for determining whether or not wear is occurring by the control device according to the first embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, identical or corresponding components are denoted by the same or corresponding reference numerals, and their descriptions may be omitted.

[0010] Figure 1 shows the state of the injection molding machine when the mold opening is complete according to the first embodiment. Figure 2 shows the state of the injection molding machine when the mold is clamped according to the first embodiment. In this specification, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction. When the mold clamping device 100 is horizontal, the X-axis direction is the mold opening and closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side in the Y-axis direction is called the operating side, and the positive side in the Y-axis direction is called the non-operating side.

[0011] As shown in Figures 1 and 2, the injection molding machine 10 includes a clamping device 100 for opening and closing the mold device 800, an ejector device 200 for ejecting the molded product formed in the mold device 800, an injection device 300 for injecting molding material into the mold device 800, a moving device 400 for moving the injection device 300 forward and backward relative to the mold device 800, a control device 700 for controlling each component of the injection molding machine 10, and a frame 900 for supporting each component of the injection molding machine 10. The frame 900 includes a clamping device frame 910 for supporting the clamping device 100 and an injection device frame 920 for supporting the injection device 300. The clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via leveling adjusters 930. The control device 700 is located in the internal space of the injection device frame 920. The components of the injection molding machine 10 will be described below.

[0012] (mold clamping device) In the description of the clamping device 100, the moving direction of the movable platen 120 when the mold is closed (for example, the positive X-axis direction) is defined as the front, and the moving direction of the movable platen 120 when the mold is opened (for example, the negative X-axis direction) is defined as the rear for the description.

[0013] The clamping device 100 performs mold closing, pressure boosting, mold clamping, pressure release, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a movable mold 820.

[0014] The clamping device 100 is, for example, a horizontal type, and the mold opening / closing direction is the horizontal direction. The clamping device 100 has a fixed platen 110 to which the fixed mold 810 is attached, a movable platen 120 to which the movable mold 820 is attached, and a moving mechanism 102 that moves the movable platen 120 in the mold opening / closing direction with respect to the fixed platen 110.

[0015] The fixed platen 110 is fixed to the clamping device frame 910. The fixed mold 810 is attached to the opposing surface of the fixed platen 110 with respect to the movable platen 120.

[0016] The movable platen 120 is arranged to be movable in the mold opening / closing direction with respect to the clamping device frame 910. A guide 101 for guiding the movable platen 120 is laid on the clamping device frame 910. The movable mold 820 is attached to the opposing surface of the movable platen 120 with respect to the fixed platen 110.

[0017] The moving mechanism 102 performs mold closing, pressure boosting, mold clamping, pressure release, and mold opening of the mold device 800 by advancing and retreating the movable platen 120 with respect to the fixed platen 110. The moving mechanism 102 has a toggle support 130 arranged at an interval from the fixed platen 110, a tie bar 140 connecting the fixed platen 110 and the toggle support 130, a toggle mechanism 150 that moves the movable platen 120 in the mold opening / closing direction with respect to the toggle support 130, a clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the clamping motor 160 into a linear motion, and a mold thickness adjustment mechanism 180 that adjusts the interval between the fixed platen 110 and the toggle support 130.

[0018] The toggle support 130 is positioned at a distance from the fixed platen 110 and is mounted on the mold clamping device frame 910 so as to be movable in the mold opening and closing direction. The toggle support 130 may also be positioned so as to be movable along a guide laid on the mold clamping device frame 910. The guide for the toggle support 130 may be the same as the guide 101 for the movable platen 120.

[0019] In this embodiment, the fixed platen 110 is fixed to the clamping device frame 910, and the toggle support 130 is arranged to be movable relative to the clamping device frame 910 in the mold opening and closing direction. However, the toggle support 130 may be fixed to the clamping device frame 910, and the fixed platen 110 may be arranged to be movable relative to the clamping device frame 910 in the mold opening and closing direction.

[0020] The tie bars 140 connect the fixed platen 110 and the toggle support 130 at a distance L in the mold opening and closing direction. Multiple tie bars 140 (for example, four) may be used. Multiple tie bars 140 are arranged parallel to the mold opening and closing direction and stretch in accordance with the clamping force. At least one tie bar 140 may be provided with a tie bar strain detector 141 that detects the strain of the tie bar 140. The tie bar strain detector 141 sends a signal indicating its detection result to the control device 700. The detection result of the tie bar strain detector 141 is used for detecting the clamping force, etc.

[0021] In this embodiment, a tie bar strain detector 141 is used as a clamping force detector to detect the clamping force, but the present invention is not limited to this. The clamping force detector is not limited to strain gauge type, but may be piezoelectric, capacitive, hydraulic, electromagnetic, etc., and its mounting position is not limited to the tie bar 140.

[0022] The toggle mechanism 150 is positioned between the movable platen 120 (an example of a first platen) and the fixed platen 110 (a second platen) for opening and closing the mold of the mold device 800, and connects them. The toggle mechanism 150 also moves the movable platen 120 (an example of a first platen) relative to the toggle support 130 in the mold opening and closing direction. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening and closing direction, and a pair of link groups that bend and extend as the crosshead 151 moves. Each pair of link groups has a first link 152 and a second link 153 that are bendable and extendable, respectively, connected by pins or the like. The first link 152 is pivotably attached to the movable platen 120 by pins or the like. The second link 153 is pivotably attached to the toggle support 130 by pins or the like. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 is moved forward or backward relative to the toggle support 130, the first link 152 and the second link 153 flex and extend, and the movable platen 120 moves forward or backward relative to the toggle support 130.

[0023] Note that the configuration of the toggle mechanism 150 is not limited to the configuration shown in Figures 1 and 2. For example, in Figures 1 and 2, each link group has five nodes, but it may also have four, and one end of the third link 154 may be connected to the node between the first link 152 and the second link 153.

[0024] The clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The clamping motor 160 moves the crosshead 151 forward and backward relative to the toggle support 130, thereby bending and extending the first link 152 and the second link 153, and moving the movable platen 120 forward and backward relative to the toggle support 130. The clamping motor 160 is directly connected to the motion conversion mechanism 170, but it may also be connected to the motion conversion mechanism 170 via a belt, pulley, or the like.

[0025] The motion conversion mechanism 170 converts the rotational motion of the clamping motor 160 into the linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0026] The mold clamping device 100 performs processes such as mold closing, pressure boosting, mold clamping, depressurization, and mold opening under the control of the control device 700.

[0027] In the mold closing process, the clamping motor 160 is driven to advance the crosshead 151 to the mold closing completion position at a set movement speed, thereby advancing the movable platen 120 and bringing the movable mold 820 into contact with the fixed mold 810. The position and movement speed of the crosshead 151 are detected using, for example, a clamping motor encoder 161. The clamping motor encoder 161 detects the rotation of the clamping motor 160 and sends a signal indicating the detection result to the control device 700.

[0028] Furthermore, the crosshead position detector for detecting the position of the crosshead 151 and the crosshead speed detector for detecting the movement speed of the crosshead 151 are not limited to the clamping motor encoder 161, and general-purpose devices can be used. Similarly, the movable platen position detector for detecting the position of the movable platen 120 and the movable platen speed detector for detecting the movement speed of the movable platen 120 are not limited to the clamping motor encoder 161, and general-purpose devices can be used.

[0029] In the boosting process, the clamping motor 160 is further driven to advance the crosshead 151 from the closed position to the clamping position, thereby generating clamping force.

[0030] In the clamping process, the clamping motor 160 is driven to maintain the position of the crosshead 151 in the clamping position. In the clamping process, the clamping force generated in the pressurization process is maintained. In the clamping process, a cavity space 801 (see Figure 2) is formed between the movable mold 820 and the fixed mold 810, and the injection unit 300 fills the cavity space 801 with liquid molding material. A molded product is obtained when the filled molding material solidifies.

[0031] The number of cavity spaces 801 may be one or more. In the latter case, multiple molded products can be obtained simultaneously. An insert material may be placed in part of the cavity space 801, and the molding material may be filled in the other part of the cavity space 801. A molded product in which the insert material and the molding material are integrated is obtained.

[0032] In the depressurization process, the clamping motor 160 is driven to retract the crosshead 151 from the clamping position to the mold opening start position, thereby retracting the movable platen 120 and reducing the clamping force. The mold opening start position and the mold closing completion position may be the same position.

[0033] In the mold opening process, the clamping motor 160 is driven to retract the crosshead 151 from the mold opening start position to the mold opening completion position at a set movement speed, thereby retracting the movable platen 120 and separating the movable mold 820 from the fixed mold 810. Subsequently, the ejector device 200 ejects the molded product from the movable mold 820.

[0034] The setting conditions for the mold closing process, the pressure boosting process, and the mold clamping process are set together as a series of setting conditions. For example, the movement speed and position of the crosshead 151 (including the mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position), and the mold clamping force in the mold closing process and the pressure boosting process are set together as a series of setting conditions. The mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position are arranged in this order from rear to front and represent the start and end points of the section in which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. There may be no movement speed switching positions. The mold clamping position and the mold clamping force may be set individually or individually.

[0035] The setting conditions for the depressurization process and the mold opening process are set similarly. For example, the movement speed and position of the crosshead 151 in the depressurization process and the mold opening process (mold opening start position, movement speed switching position, and mold opening completion position) are set together as a series of setting conditions. The mold opening start position, movement speed switching position, and mold opening completion position are arranged in this order from front to back and represent the start and end points of the sections in which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. There may be no movement speed switching positions. The mold opening start position and the mold closing completion position may be the same position. Also, the mold opening completion position and the mold closing start position may be the same position.

[0036] Alternatively, the movement speed and position of the movable platen 120 may be set instead of the movement speed and position of the crosshead 151. Furthermore, the clamping force may be set instead of the position of the crosshead (e.g., the clamping position) or the position of the movable platen.

[0037] Incidentally, the toggle mechanism 150 amplifies the driving force of the clamping motor 160 and transmits it to the movable platen 120. This amplification ratio is also called the toggle ratio. The toggle ratio changes depending on the angle θ between the first link 152 and the second link 153 (hereinafter also referred to as the "link angle θ"). The link angle θ can be determined from the position of the crosshead 151. The toggle ratio is maximized when the link angle θ is 180°.

[0038] If the thickness of the mold device 800 changes due to replacement of the mold device 800 or a change in the temperature of the mold device 800, the mold thickness is adjusted so that a predetermined clamping force is obtained during mold clamping. In mold thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle support 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the time of mold touch when the movable mold 820 touches the fixed mold 810.

[0039] The mold clamping device 100 has a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the mold thickness by adjusting the distance L between the fixed platen 110 and the toggle support 130. The timing of the mold thickness adjustment is, for example, between the end of one molding cycle and the start of the next molding cycle. The mold thickness adjustment mechanism 180 includes, for example, a screw shaft 181 formed at the rear end of the tie bar 140, a screw nut 182 that is rotatably and immovably held by the toggle support 130, and a mold thickness adjustment motor 183 that rotates the screw nut 182 that is screwed onto the screw shaft 181.

[0040] A screw shaft 181 and screw nut 182 are provided for each tie bar 140. The rotational driving force of the mold thickness adjustment motor 183 may be transmitted to multiple screw nuts 182 via a rotational driving force transmission unit 185. Multiple screw nuts 182 can be rotated synchronously. It is also possible to rotate multiple screw nuts 182 individually by changing the transmission path of the rotational driving force transmission unit 185.

[0041] The rotational drive force transmission unit 185 is composed of, for example, gears. In this case, driven gears are formed on the outer circumference of each screw nut 182, a drive gear is attached to the output shaft of the mold thickness adjustment motor 183, and an intermediate gear that meshes with the multiple driven gears and the drive gear is rotatably held in the center of the toggle support 130. Note that the rotational drive force transmission unit 185 may be composed of a belt or pulley instead of gears.

[0042] The operation of the mold thickness adjustment mechanism 180 is controlled by the control device 700. The control device 700 drives the mold thickness adjustment motor 183 to rotate the screw nut 182. As a result, the position of the toggle support 130 relative to the tie bar 140 is adjusted, and the distance L between the fixed platen 110 and the toggle support 130 is adjusted. Multiple mold thickness adjustment mechanisms may be used in combination.

[0043] The interval L is detected using the mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the amount and direction of rotation of the mold thickness adjustment motor 183 and sends a signal indicating the detection result to the control device 700. The detection result of the mold thickness adjustment motor encoder 184 is used to monitor and control the position and interval L of the toggle support 130. Note that the toggle support position detector for detecting the position of the toggle support 130 and the interval detector for detecting the interval L are not limited to the mold thickness adjustment motor encoder 184, but general-purpose devices can be used.

[0044] The clamping device 100 may have a mold temperature controller that adjusts the temperature of the mold device 800. The mold device 800 has a flow path for a temperature-controlled medium inside it. The mold temperature controller adjusts the temperature of the mold device 800 by adjusting the temperature of the temperature-controlled medium supplied to the flow path of the mold device 800.

[0045] In this embodiment, the mold clamping device 100 is a horizontal type in which the mold opening and closing direction is horizontal, but it may also be a vertical type in which the mold opening and closing direction is vertical.

[0046] In this embodiment, the clamping device 100 has a clamping motor 160 as a drive source, but a hydraulic cylinder may be used instead of the clamping motor 160. Furthermore, the clamping device 100 may have a linear motor for opening and closing the mold, and an electromagnet for clamping the mold.

[0047] (Ejector device) In describing the ejector device 200, similar to the description of the clamping device 100, the direction of movement of the movable platen 120 when the mold is closed (for example, the positive X-axis direction) is described as forward, and the direction of movement of the movable platen 120 when the mold is open (for example, the negative X-axis direction) is described as backward.

[0048] The ejector device 200 is attached to the movable platen 120 and moves back and forth together with the movable platen 120. The ejector device 200 includes an ejector rod 210 that ejects the molded product from the mold device 800 and a drive mechanism 220 that moves the ejector rod 210 in the direction of movement of the movable platen 120 (in the X-axis direction).

[0049] The ejector rod 210 is positioned to move back and forth within a through-hole in the movable platen 120. The front end of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The front end of the ejector rod 210 may or may not be connected to the ejector plate 826.

[0050] The drive mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts the rotational motion of the ejector motor into the linear motion of the ejector rod 210. The motion conversion mechanism includes a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0051] The ejector device 200 performs the ejection process under the control of the control device 700. In the ejection process, the ejector rod 210 is advanced from the standby position to the ejection position at a set travel speed, thereby advancing the ejector plate 826 and ejecting the molded product. Subsequently, the ejector motor is driven to retract the ejector rod 210 at a set travel speed, retracting the ejector plate 826 back to its original standby position.

[0052] The position and speed of the ejector rod 210 are detected, for example, using an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and sends a signal indicating the detection result to the control device 700. Note that the ejector rod position detector, which detects the position of the ejector rod 210, and the ejector rod speed detector, which detects the speed of the ejector rod 210, are not limited to ejector motor encoders, but general-purpose devices can be used.

[0053] (injection device) In the description of the injection device 300, unlike the descriptions of the clamping device 100 and the ejector device 200, the direction of movement of the screw 330 during filling (for example, the negative X-axis direction) is described as forward, and the direction of movement of the screw 330 during metering (for example, the positive X-axis direction) is described as backward.

[0054] The injection device 300 is mounted on a slide base 301, which is positioned to move back and forth relative to the injection device frame 920. The injection device 300 is positioned to move back and forth relative to the mold device 800. The injection device 300 touches the mold device 800 and fills the cavity space 801 within the mold device 800 with molding material. The injection device 300 includes, for example, a cylinder 310 for heating the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 positioned within the cylinder 310 to move back and forth and to rotate, a metering motor 340 for rotating the screw 330, an injection motor 350 for moving the screw 330 back and forth, and a load detector 360 for detecting the load transmitted between the injection motor 350 and the screw 330.

[0055] The cylinder 310 heats the molding material supplied to its interior from the supply port 311. The molding material includes, for example, resin. The molding material is formed, for example, into pellets and supplied to the supply port 311 in a solid state. The supply port 311 is formed at the rear of the cylinder 310. A cooler 312, such as a water-cooled cylinder, is provided on the outer circumference of the rear of the cylinder 310. In front of the cooler 312, a heater 313, such as a band heater, and a temperature detector 314 are provided on the outer circumference of the cylinder 310.

[0056] The cylinder 310 is divided into multiple zones along its axial direction (for example, the X-axis direction). A heater 313 and a temperature detector 314 are provided in each of the multiple zones. A set temperature is set for each of the multiple zones, and the control device 700 controls the heater 313 so that the temperature detected by the temperature detector 314 becomes the set temperature.

[0057] The nozzle 320 is located at the front end of the cylinder 310 and is pressed against the mold device 800. A heater 313 and a temperature detector 314 are provided on the outer circumference of the nozzle 320. The control device 700 controls the heater 313 so that the detected temperature of the nozzle 320 reaches a set temperature.

[0058] The screw 330 is rotatably and reciprocally positioned within the cylinder 310. When the screw 330 is rotated, the molding material is fed forward along the helical groove of the screw 330. As the molding material is fed forward, it is gradually melted by the heat from the cylinder 310. As the liquid molding material is fed forward to the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is retracted. Then, when the screw 330 is advanced, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled into the mold device 800.

[0059] A backflow prevention ring 331 is mounted on the front of the screw 330 so as to be able to move back and forth, acting as a backflow prevention valve to prevent backflow of the molding material from the front to the rear of the screw 330 when the screw 330 is pushed forward.

[0060] When the screw 330 is advanced, the backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and retracts relative to the screw 330 to a closed position (see Figure 2) that blocks the flow path of the molding material. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

[0061] On the other hand, when the screw 330 is rotated, the backflow prevention ring 331 is pushed forward by the pressure of the molding material being sent forward along the helical groove of the screw 330, and moves relative to the screw 330 to an open position (see Figure 1) that opens the flow path of the molding material. As a result, the molding material is sent forward of the screw 330.

[0062] The backflow prevention ring 331 may be either a co-rotating type that rotates together with the screw 330, or a non-co-rotating type that does not rotate together with the screw 330.

[0063] The injection device 300 may also have a drive source that moves the backflow prevention ring 331 back and forth between an open position and a closed position relative to the screw 330.

[0064] The metering motor 340 rotates the screw 330. The drive source for rotating the screw 330 is not limited to the metering motor 340; for example, a hydraulic pump or the like may also be used.

[0065] The injection motor 350 moves the screw 330 forward and backward. Between the injection motor 350 and the screw 330, there is a motion conversion mechanism that converts the rotational motion of the injection motor 350 into the linear motion of the screw 330. The motion conversion mechanism has, for example, a screw shaft and a screw nut that screws onto the screw shaft. Balls or rollers may be provided between the screw shaft and the screw nut. The drive source for moving the screw 330 forward and backward is not limited to the injection motor 350, but may also be, for example, a hydraulic cylinder.

[0066] The load detector 360 detects the load transmitted between the injection motor 350 and the screw 330. The detected load is converted into pressure by the control device 700. The load detector 360 is installed in the load transmission path between the injection motor 350 and the screw 330 and detects the load acting on the load detector 360.

[0067] The load detector 360 sends a signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into pressure acting between the screw 330 and the molding material, and is used for controlling and monitoring the pressure the screw 330 receives from the molding material, the back pressure on the screw 330, and the pressure acting from the screw 330 on the molding material.

[0068] The pressure detector used to detect the pressure of the molding material is not limited to the load detector 360, but can be any general-purpose pressure detector. For example, a nozzle pressure sensor or a mold pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320. The mold pressure sensor is installed inside the mold device 800.

[0069] The injection device 300 performs processes such as metering, filling, and holding pressure under the control of the control device 700. The filling and holding pressure processes may be collectively referred to as the injection process.

[0070] In the weighing process, the weighing motor 340 is driven to rotate the screw 330 at a set rotational speed, and the molding material is fed forward along the helical groove of the screw 330. As this occurs, the molding material is gradually melted. As the liquid molding material is fed forward to the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is retracted. The rotational speed of the screw 330 is detected, for example, using a weighing motor encoder 341. The weighing motor encoder 341 detects the rotation of the weighing motor 340 and sends a signal indicating the detection result to the control device 700. Note that the screw rotational speed detector for detecting the rotational speed of the screw 330 is not limited to the weighing motor encoder 341, and a general type can be used.

[0071] In the weighing process, the injection motor 350 may be driven to apply a set back pressure to the screw 330 in order to limit the rapid retraction of the screw 330. The back pressure on the screw 330 is detected, for example, using a load detector 360. The weighing process is completed when the screw 330 has retracted to the weighing completion position and a predetermined amount of molding material has accumulated in front of the screw 330.

[0072] The position and rotational speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, the metering start position, rotational speed switching position, and metering completion position are set. These positions are arranged in this order from front to back and represent the start and end points of the sections in which the rotational speed is set. The rotational speed is set for each section. There may be one or more rotational speed switching positions. The rotational speed switching positions may not be set. In addition, back pressure is set for each section.

[0073] In the filling process, the injection motor 350 is driven to advance the screw 330 at a set speed, filling the cavity space 801 in the mold device 800 with the liquid molding material accumulated in front of the screw 330. The position and speed of the screw 330 are detected, for example, using an injection motor encoder 351. The injection motor encoder 351 detects the rotation of the injection motor 350 and sends a signal indicating the detection result to the control device 700. When the position of the screw 330 reaches the set position, a switchover from the filling process to the holding pressure process (so-called V / P switching) occurs. The position at which the V / P switching occurs is also called the V / P switching position. The set speed of the screw 330 may be changed depending on the position and time of the screw 330.

[0074] The position and movement speed of the screw 330 during the filling process are set together as a series of setting conditions. For example, the filling start position (also called the "injection start position"), the movement speed switching position, and the V / P switching position are set. These positions are arranged in this order from rear to front and represent the start and end points of the sections in which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching positions may not be set at all.

[0075] For each section in which the movement speed of the screw 330 is set, an upper limit is set for the pressure of the screw 330. The pressure of the screw 330 is detected by the load sensor 360. If the pressure of the screw 330 is below the set pressure, the screw 330 moves forward at the set movement speed. On the other hand, if the pressure of the screw 330 exceeds the set pressure, for the purpose of protecting the mold, the screw 330 moves forward at a slower movement speed than the set movement speed so that the pressure of the screw 330 becomes below the set pressure.

[0076] Furthermore, during the filling process, after the screw 330 reaches the V / P switching position, the screw 330 may be temporarily stopped at the V / P switching position, and then the V / P switching may be performed. Immediately before the V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed. In addition, the screw position detector that detects the position of the screw 330 and the screw movement speed detector that detects the movement speed of the screw 330 are not limited to the injection motor encoder 351, but general-purpose ones can be used.

[0077] In the holding pressure process, the injection motor 350 is driven to push the screw 330 forward, maintaining the pressure of the molding material at the front end of the screw 330 (hereinafter also referred to as "holding pressure") at a set pressure, and pushing the molding material remaining in the cylinder 310 toward the mold device 800. This allows for the replenishment of molding material lost due to cooling shrinkage within the mold device 800. The holding pressure is detected, for example, using a load detector 360. The set value of the holding pressure may be changed according to the elapsed time from the start of the holding pressure process. Multiple holding pressures and holding times for maintaining the holding pressure in the holding pressure process may be set, and may be set together as a series of setting conditions.

[0078] During the holding pressure process, the molding material in the cavity space 801 within the mold device 800 is gradually cooled, and upon completion of the holding pressure process, the entrance to the cavity space 801 is sealed with solidified molding material. This state is called a gate seal, and prevents backflow of molding material from the cavity space 801. After the holding pressure process, the cooling process begins. During the cooling process, the molding material in the cavity space 801 is solidified. To shorten the molding cycle time, a metering process may be performed during the cooling process.

[0079] In this embodiment, the injection device 300 is an in-line screw type, but a pre-plasticization type or the like may also be used. In a pre-plasticization injection device, the molding material molten in a plasticizing cylinder is supplied to the injection cylinder, and the molding material is injected from the injection cylinder into the mold device. In the plasticizing cylinder, a screw is arranged to be rotatable but unable to move back and forth, or a screw is arranged to be rotatable and able to move back and forth. On the other hand, a plunger is arranged to be able to move back and forth in the injection cylinder.

[0080] Furthermore, although the injection device 300 in this embodiment is a horizontal type with the axial direction of the cylinder 310 being horizontal, it may also be a vertical type with the axial direction of the cylinder 310 being vertical. The clamping device combined with the vertical injection device 300 may be vertical or horizontal. Similarly, the clamping device combined with the horizontal injection device 300 may be horizontal or vertical.

[0081] (Mobile device) In describing the moving device 400, similar to the description of the injection device 300, the direction of movement of the screw 330 during filling (for example, the negative X-axis direction) is described as forward, and the direction of movement of the screw 330 during metering (for example, the positive X-axis direction) is described as backward.

[0082] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. The moving device 400 also presses the nozzle 320 against the mold device 800, generating nozzle touch pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

[0083] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectional rotatable pump, and by switching the rotation direction of the motor 420, it can draw in working fluid (e.g., oil) from either the first port 411 or the second port 412 and discharge it from the other to generate hydraulic pressure. The hydraulic pump 410 can also draw working fluid from a tank and discharge it from either the first port 411 or the second port 412.

[0084] Motor 420 operates the hydraulic pump 410. Motor 420 drives the hydraulic pump 410 with a rotational direction and rotational torque corresponding to the control signal from the control device 700. Motor 420 may be an electric motor or an electric servo motor.

[0085] The hydraulic cylinder 430 comprises a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is fixed to the injection device 300. The piston 432 divides the inside of the cylinder body 431 into a front chamber 435 as a first chamber and a rear chamber 436 as a second chamber. The piston rod 433 is fixed to the fixed platen 110.

[0086] The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via a first passage 401. The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 via the first passage 401, pushing the injection device 300 forward. As the injection device 300 moves forward, the nozzle 320 is pressed against the fixed mold 810. The front chamber 435 functions as a pressure chamber that generates nozzle touch pressure on the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0087] Meanwhile, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via the second passage 402. The working fluid discharged from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second passage 402, pushing the injection device 300 backward. As the injection device 300 is retracted, the nozzle 320 is separated from the fixed mold 810.

[0088] In this embodiment, the moving device 400 includes a hydraulic cylinder 430, but the present invention is not limited thereto. For example, instead of the hydraulic cylinder 430, an electric motor and a motion conversion mechanism that converts the rotational motion of the electric motor into the linear motion of the injection device 300 may be used.

[0089] (Control device) The control device 700 is, for example, a computer and, as shown in Figures 1 and 2, has a CPU (Central Processing Unit) 701, a storage medium 702 such as memory, an input interface 703, and an output interface 704. The control device 700 performs various controls by having the CPU 701 execute a program stored in the storage medium 702. The control device 700 also receives signals from the outside through the input interface 703 and transmits signals to the outside through the output interface 704.

[0090] The control device 700 repeatedly manufactures molded products by repeatedly performing processes such as metering, mold closing, pressure increasing, mold clamping, filling, holding pressure, cooling, depressurization, mold opening, and ejection. A series of operations to obtain a molded product, such as the operations from the start of one metering process to the start of the next metering process, is also called a "shot" or "molding cycle." The time required for one shot is also called the "molding cycle time" or "cycle time."

[0091] A single molding cycle includes, for example, a weighing process, a mold closing process, a pressurizing process, a clamping process, a filling process, a holding pressure process, a cooling process, a depressurizing process, a mold opening process, and an ejection process, in this order. The order here refers to the order in which each process begins. The filling, holding pressure, and cooling processes take place during the clamping process. The start of the clamping process may coincide with the start of the filling process. The completion of the depressurizing process coincides with the start of the mold opening process.

[0092] Furthermore, multiple processes may be performed simultaneously to shorten the molding cycle time. For example, the metering process may be performed during the cooling process of the previous molding cycle, or during the mold clamping process. In this case, the mold closing process may be performed at the beginning of the molding cycle. The filling process may also be started during the mold closing process. The ejection process may also be started during the mold opening process. If an on-off valve is provided to open and close the flow path of the nozzle 320, the mold opening process may be started during the metering process. This is because even if the mold opening process is started during the metering process, if the on-off valve closes the flow path of the nozzle 320, the molding material will not leak from the nozzle 320.

[0093] Furthermore, a single molding cycle may include steps other than the weighing step, mold closing step, pressurization step, mold clamping step, filling step, holding pressure step, cooling step, depressurization step, mold opening step, and ejection step.

[0094] For example, after the holding pressure process is completed and before the metering process begins, a pre-metering suck-back process may be performed in which the screw 330 is retracted to a preset metering start position. This reduces the pressure of the molding material accumulated in front of the screw 330 before the metering process begins and prevents the screw 330 from retracting too quickly at the start of the metering process.

[0095] Furthermore, after the metering process is completed and before the filling process begins, a post-metering suck-back process may be performed in which the screw 330 is retracted to a preset filling start position (also called the "injection start position"). This reduces the pressure of the molding material accumulated in front of the screw 330 before the filling process begins and prevents leakage of the molding material from the nozzle 320 before the filling process begins.

[0096] The control device 700 is connected to an operating device 750 that accepts user input operations and a display device 760 that displays a screen. The operating device 750 and the display device 760 may be integrated, for example, by a touch panel 770. The touch panel 770, as the display device 760, displays a screen under the control of the control device 700. The screen of the touch panel 770 may display information such as the settings of the injection molding machine 10 and the current status of the injection molding machine 10. The screen of the touch panel 770 may also display operation parts such as buttons and input fields that accept user input operations. The touch panel 770, as the operating device 750, detects user input operations on the screen and outputs a signal corresponding to the input operation to the control device 700. This allows, for example, the user to operate the operation parts provided on the screen while confirming the information displayed on the screen to set the injection molding machine 10 (including inputting setting values). Furthermore, by operating the operation parts provided on the screen, the user can make the injection molding machine 10 operate in accordance with the operation part. The operation of the injection molding machine 10 may also include the operation (including stopping) of, for example, the clamping device 100, the ejector device 200, the injection device 300, the moving device 400, etc. Furthermore, the operation of the injection molding machine 10 may also include switching the screens displayed on the touch panel 770, which serves as the display device 760.

[0097] Although the operating device 750 and display device 760 in this embodiment have been described as being integrated as a touch panel 770, they may be provided independently. Furthermore, multiple operating devices 750 may be provided. The operating device 750 and display device 760 are positioned on the operating side (negative Y-axis direction) of the clamping device 100 (more specifically, the fixed platen 110).

[0098] (Configuration of the toggle mechanism) Next, the configuration of the toggle mechanism 150 will be described. Figure 3 is a diagram of the configuration of the toggle mechanism 150 provided in the injection molding machine 10 according to the first embodiment.

[0099] As shown in Figure 3, the link connection portion 131 of the toggle support 130 is connected to the second link 153 by a second connecting mechanism 42. A connecting pin 51 is used for the connection by the second connecting mechanism 42. The connecting pin 51 is fixed in place by preventing rotation in the connecting hole of the link connection portion 131 of the toggle support 130, and is slidable between the connecting pin 51 and a bush 42B (see Figure 7) which is press-fitted into the connecting hole 42A (see Figure 7) of the second link 153. The sliding surface between the bush 42B and the connecting pin 51 is lubricated.

[0100] The first link 152 and the second link 153 are connected by a third connecting mechanism 43. A connecting pin 52 is used for the connection by the third connecting mechanism 43. The connecting pin 52 is fixed in place by the connecting hole of one of the first links 152 and is slidable between the connecting pin 52 and a bush 43B (see Figure 7) which is press-fitted into the connecting hole 43A (see Figure 7) of the other connecting member, the second link 153. The sliding surface between the bush 43B and the connecting pin 52 is lubricated.

[0101] Similarly, the connecting pins 50, 53-54 are fixed to one connecting member in the connecting mechanism described later (first connecting mechanism 41, fourth connecting mechanism 44, fifth connecting mechanism 45), and are slidable between them and a bush press-fitted into the other connecting member. The sliding surfaces between the bush and the connecting pins 50, 53-54 are lubricated.

[0102] The link connection portion 121 of the movable platen 120 is connected to the first link 152 by the first connecting mechanism 41. A connecting pin 50 is used for the connection by the first connecting mechanism 41.

[0103] The crosshead 151 is connected to the third link 154 by a fourth connecting mechanism 44. A connecting pin 53 is used for the connection by the fourth connecting mechanism 44. The third link 154 is connected to the second link 153 on approximately the positive Z-axis side by a fifth connecting mechanism 45. A connecting pin 54 is used for the connection by the fifth connecting mechanism 45.

[0104] In the processes of mold closing, pressure boosting, mold clamping, depressurization, and mold opening, the thrust generated by the drive of the mold clamping motor 160 moves the crosshead 151 in the X-axis direction. When the crosshead 151 moves in the X-axis direction, the second link 153, to which the crosshead 151 is connected via the third link 154, also moves. The second link 153 moves in an arc on the XZ axis plane with the second connecting mechanism 42 as the center. As a result, the first link 152 and the second link 153 flex and extend, and the movable platen 120 moves forward and backward relative to the toggle support 130.

[0105] In this embodiment, the second link 153 is provided with a strain gauge 156 on its side facing approximately the positive Z-axis direction. The signal generated by the strain gauge 156 is transmitted to the control device 700. The control device 700 then determines, based on the signal from the strain gauge 156, whether or not wear is occurring in the coupling mechanism (for example, the second coupling mechanism 42 and the third coupling mechanism 43) connected to the second link 153.

[0106] Figure 4 is a diagram showing an example configuration of the control device 700 according to this embodiment. As shown in Figure 4, the control circuit 701 provided in the control device 700 realizes the configuration shown in Figure 4. The configuration shown in Figure 4 may be realized by hardware connections, by software control, or by a combination of hardware connections and software control.

[0107] As shown in Figure 4, the control device 700 comprises a control unit 711, an acquisition unit 712, a determination unit 713, and an output unit 714.

[0108] The control unit 711 controls the clamping motor 160 during the mold closing, pressure boosting, clamping, depressurization, and mold opening processes. For example, during the depressurization process, the control unit 711 drives and controls the clamping motor 160 to retract the crosshead 151 from the clamping position to the mold opening start position.

[0109] The acquisition unit 712 acquires the amount of strain (an example of change) generated in the second link 153 (an example of a link member) based on the signal (detected value) from the strain gauge 156 (an example of a detection unit) installed on the second link 153 (an example of a link member) during the depressurization process. In this embodiment, it is determined whether or not wear has occurred according to the amount of strain acquired during the depressurization process. The strain generated in the second link 153 in this embodiment will now be described.

[0110] Figure 5 shows the forces generated within the toggle mechanism 150 during the depressurization process according to the first embodiment. As shown in Figure 5, the thrust force generated by the drive of the clamping motor 160 generates a force 1501 that moves the crosshead 151 in the negative X-axis direction. This movement of the crosshead 151 in the negative X-axis direction causes the third link 154, which is connected by the fourth connecting mechanism 44, to also begin moving in the negative X-axis direction.

[0111] The second link 153 is also connected to the third link 154 by a fifth connecting mechanism 45 located approximately on the negative Z-axis side. Therefore, as the third link 154 moves, a force 1502 is generated that causes the second link 153 to move approximately on the negative Z-axis side where the third link 154 is located, centered on the second connecting mechanism 42. When the second link 153 moves in response to this force 1502, if wear occurs in the third connecting mechanism 43, friction occurs between the second link 153 and the connecting pin 52 in the third connecting mechanism 43, generating a force 1503.

[0112] In a normal depressurization process, the clamping force decreases, causing the strain in the second link 153 to decrease. However, if wear occurs in a connecting mechanism such as the third connecting mechanism 43, a force opposite to the force 1502 is generated from the connecting mechanism, causing the strain in the second link 153 to increase. Therefore, in this embodiment, whether or not wear is occurring is determined based on whether or not the strain increases during the depressurization process.

[0113] Figure 6 is a perspective view showing the shape of the second link 153 according to this embodiment, and Figure 7 is a front view showing the shape of the second link 153 according to this embodiment.

[0114] The second link 153 shown in Figures 6 and 7 is formed from casting. The second link 153 in this embodiment is one of a plurality of links (an example of a plurality of link members) that constitute the toggle mechanism 150, and has a connecting hole 42A (an example of a first connecting part) for forming a second connecting mechanism 42 and a connecting hole 43A (an example of a first connecting part) for forming a third connecting mechanism 43 in order to connect the fixed platen 110 (second platen) and the movable platen 120 (first platen).

[0115] The second link 153 has connecting holes 42A and 43A formed such that the distance L1 from the center 42C of connecting hole 42A and the center 43C of connecting hole 43A to the side surface in the approximately positive Z-axis direction is equal to the distance L1 from the side surface in the approximately negative Z-axis direction.

[0116] Furthermore, the second link 153 of this embodiment has a connecting hole 45A (an example of a second connecting part) that forms a fifth connecting mechanism 45 in order to transmit the clamping force from the clamping motor 160 (an example of a drive source) to the mold device 800.

[0117] The center 45C of the connecting hole 45A is located approximately at the center of the second link 153 in relation to its length in the X-axis direction. Furthermore, the center 45C of the connecting hole 45A is located towards the negative Z-axis direction. This allows it to connect to the third link 154, which is located in the negative Z-axis direction.

[0118] A bushing 42B is fitted into the connecting hole 42A of the second link 153 using a shrink fit. The bushing 42B has a sliding surface on its inner side and functions as a bearing for the connecting pin 51 which is provided to be in contact with the inner side.

[0119] Similarly, a bush 43B is fitted into the connecting hole 43A of the second link 153 using a shrink fit. The bush 43B has a sliding surface on its inside and functions as a bearing for the connecting pin 52 which is provided to be in contact with the inside.

[0120] For example, when the bush 43B wears down, the coefficient of friction of the sliding surface increases. As a result, when a force 1502 in the negative Z-axis direction from the third link 154 is generated in the connecting hole 45A that constitutes the fifth connecting mechanism 45, if the sliding is reduced by friction generated inside the bush 43B, a force 1503 in the positive Z-axis direction will be generated.

[0121] Furthermore, when the bush 42B wears down, the coefficient of friction of the sliding surface increases. As a result, when a force 1502 in the negative Z-axis direction is generated in the connecting hole 45A that constitutes the fifth connecting mechanism 45, if the sliding is reduced by friction generated inside the bush 42B, a force 1504 in the positive Z-axis direction is generated.

[0122] These forces cause strain in each of the three regions 601, 602, and 603 on the side of the second link 153 that is on the positive Z-axis side. In this embodiment, the control device 700 measures the strain generated in any one of these regions 601 to 603 and determines whether or not wear has occurred. In this embodiment, an example is described in which a strain gauge 156 (an example of a detection unit) is provided in region 602, but strain may also be measured in the other regions 601 and 603 to determine whether or not wear has occurred.

[0123] Returning to Figure 4, the determination unit 713 determines whether the amount of strain acquired by the acquisition unit 712 exceeds a predetermined threshold T1.

[0124] Figure 8 illustrates the change in strain amount acquired by the acquisition unit 712 during the depressurization process of this embodiment. In the example shown in Figure 8, the horizontal axis represents the passage of time, with time "0" being the time when depressurization began. The vertical axis represents the strain amount and clamping force.

[0125] As shown in Figure 8, after the start of depressurization, the clamping force 1801 decreases over time and approaches "0".

[0126] In the example shown in Figure 8, the change in strain amount 1802 when there is no wear and the change in strain amount 1803 when there is wear are shown. In the example shown in Figure 8, strain is already present at the start of depressurization due to the clamping force in the clamping process. When there is no wear, as shown in the change in strain amount 1802, the strain amount approaches "0" after a predetermined time has elapsed.

[0127] On the other hand, in the case of wear, as shown in the change in strain amount 1803, after depressurization begins, the absolute value of the strain amount increases and then gradually decreases. In this embodiment, a threshold T1 (absolute value) is set as the criterion for determining whether or not wear has occurred.

[0128] Therefore, the determination unit 713 determines that at time t1, the absolute value of the strain amount has become greater than the threshold T1, and thus at least one of the bushes 42B and 43B of the second link 153 has worn out.

[0129] In this embodiment, an example was described in which a threshold T1, which serves as the basis for the absolute value of the strain, is set. However, the threshold T1 is not limited to being based on the absolute value of the strain; for example, a threshold may be set based on the rate of change of the strain.

[0130] The output unit 714 outputs the determination result from the determination unit 713. The output destination for the determination result could be, for example, a display device 760, but it could also be a terminal device used by the operator performing the remote operation, or a monitoring center that monitors the injection molding machine.

[0131] Next, the procedure for determining whether or not wear is occurring by the control device 700 according to this embodiment will be described. Figure 9 is a flowchart showing the procedure for determining whether or not wear is occurring by the control device 700 according to this embodiment. In the flowchart shown in Figure 9, it is assumed that the process has progressed to the mold clamping process.

[0132] First, after the clamping process is completed, the control unit 711 instructs the clamping motor 160 to start the depressurization process (S901). This initiates control of the clamping motor 160 during the depressurization process, causing the crosshead 151 to move in the negative X-axis direction.

[0133] Next, the acquisition unit 712 acquires the amount of strain from the signal output from the strain gauge 156 (S902).

[0134] The determination unit 713 determines whether the absolute value of the acquired strain is greater than the threshold T1 (S903). If it is determined that the absolute value of the acquired strain is greater than the threshold T1 (S903: Yes), the output unit 714 outputs a message to the display device 760 or the like indicating that wear has occurred (S904), and terminates the process.

[0135] On the other hand, if the determination unit 713 determines that the absolute value of the acquired strain amount is less than or equal to the threshold T1 (S903: No), the determination unit 713 determines whether or not the depressurization process has been completed (S905). If it determines that the depressurization process has not been completed (S905: No), the process is repeated from S902.

[0136] On the other hand, if the determination unit 713 determines that the depressurization process is complete (S905: Yes), it terminates the process.

[0137] In this embodiment, by performing the above-described process, it is possible to determine whether or not wear is occurring based on the amount of strain during the depressurization process.

[0138] (Modified version of the first embodiment) The above-described embodiment explains the case where the monitoring device for the injection molding machine 10 is a control device 700. However, the above-described embodiment does not limit the monitoring device for the injection molding machine 10 to the control device 700; any device capable of monitoring the injection molding machine 10 is acceptable. As a modified example, the monitoring device for the injection molding machine 10 may be a monitoring center connected to the injection molding machine 10 via a network. In this case, the monitoring center receives information via a public network indicating that the depressurization process has started, and information indicating the amount of strain obtained from the strain gauge 156. The monitoring center then determines whether or not wear has occurred based on the received information.

[0139] Furthermore, the diagnostic device may be a portable diagnostic device owned by an operator who periodically diagnoses the injection molding machine 10. When performing the diagnosis, the operator attaches a strain gauge 156 to one of the areas 601 to 603 of the second link 153 described above. The attached strain gauge 156 is connected to the diagnostic device. The diagnostic device then determines whether wear is occurring based on whether the amount of strain indicated by the signal received from the strain gauge 156 is greater than the threshold T1.

[0140] (Second embodiment) In the first embodiment, an example was described in which the amount of strain is detected using a strain gauge 156 as the amount of change occurring in the second link 153 (an example of a link member). However, the above-described embodiment does not limit the amount of change occurring in the second link 153 (an example of a link member) to the amount of strain. Therefore, in the second embodiment, a case in which acceleration is detected as the amount of change occurring in the second link 153 will be described. In this embodiment, the same reference numerals are assigned to components similar to those in the first embodiment, and their descriptions are omitted.

[0141] In this embodiment, an acceleration sensor is provided on the second link 153 (an example of a link member) instead of the strain gauge 156. In this embodiment, the acceleration sensor is provided in region 602 of the second link 153 shown in Figure 7. In this embodiment, it is provided in region 602, but it may be provided in other regions.

[0142] The acquisition unit 712 acquires the acceleration (an example of change) generated in the second link 153 (an example of a link member) based on the signal (detected value) from the acceleration sensor installed on the second link 153 during the depressurization process. In this embodiment, it is determined whether or not wear has occurred according to the acceleration acquired during the depressurization process. As described above, when the bushes 43B and 42B wear out, the coefficient of friction of the sliding surface increases. Therefore, when a force 1502 is generated during the depressurization process, vibration (acceleration) occurs in region 602 due to friction generated inside the bushes 43B and 42B.

[0143] The determination unit 713 determines whether the absolute value of the acceleration acquired by the acquisition unit 712 exceeds a predetermined threshold T2.

[0144] Figure 10 illustrates the change in acceleration acquired by the acquisition unit 712 during the depressurization process of this embodiment. In the example shown in Figure 10, the horizontal axis represents the passage of time, with time "0" being the time when depressurization began. The vertical axis represents acceleration and clamping force.

[0145] As shown in Figure 10, after the start of depressurization, the clamping force 1001 decreases over time and approaches a clamping force of "0".

[0146] The example shown in Figure 10 illustrates the change in acceleration 1002 when wear occurs. In the example shown in Figure 10, no acceleration (vibration) occurs at the start of depressurization. When wear occurs in the bushings 42B and 43B of the second link 153, acceleration (vibration) occurs when the second link 153 moves in an arc around the second connecting mechanism 42. In this embodiment, a threshold T2 (absolute value) is set as a criterion for determining whether or not wear has occurred.

[0147] The determination unit 713 determines that an abnormality exists if the absolute value of the acceleration (vibration) is greater than or equal to a predetermined threshold T2. Therefore, the determination unit 713 determines that at time t2, the absolute value of the acceleration became greater than the threshold T2, and thus at least one of the bushes 42B and 43B of the second link 153 has worn out. The output unit 714 then outputs the determination result from the determination unit 713.

[0148] Next, the procedure for determining whether or not wear is occurring by the control device 700 according to this embodiment will be described. Figure 11 is a flowchart showing the procedure for determining whether or not wear is occurring by the control device 700 according to this embodiment. In the flowchart shown in Figure 11, it is assumed that the process has progressed to the mold clamping process.

[0149] First, after the mold clamping process is completed, the control unit 711 instructs the mold clamping motor 160 to start the depressurization process (S1101).

[0150] Next, the acquisition unit 712 acquires acceleration from the signal output from the acceleration sensor (S1102).

[0151] The determination unit 713 determines whether the absolute value of the acquired acceleration is greater than the threshold T2 (S1103). If it is determined that the absolute value of the acquired acceleration is greater than the threshold T2 (S1103: Yes), the output unit 714 outputs a message to the display device 760 or the like indicating that wear has occurred (S1104), and terminates the process.

[0152] On the other hand, if the determination unit 713 determines that the absolute value of the acquired acceleration is less than or equal to the threshold T2 (S1103: No), the determination unit 713 determines whether or not the depressurization process has been completed (S1105). If it determines that the depressurization process has not been completed (S1105: No), the process returns to S1102.

[0153] On the other hand, if the determination unit 713 determines that the depressurization process is complete (S1105: Yes), it terminates the process.

[0154] In this embodiment, by performing the above-described process, it is possible to determine whether or not wear is occurring based on acceleration during the depressurization process.

[0155] (Modified version of the second embodiment) The second embodiment, like the modification of the first embodiment, may be any device capable of monitoring the injection molding machine 10. For example, it may be a monitoring center connected to the injection molding machine 10 via a network, or it may be a portable diagnostic device owned by an operator who diagnoses the injection molding machine 10.

[0156] Although the embodiments and modifications described above illustrate examples of determining whether or not wear is occurring in the second link 153, the method is not limited to the second link 153. Any of the multiple link members constituting the toggle mechanism 150 that transmit the fastening force from the clamping motor 160 may be used.

[0157] In the embodiments and modifications described above, when performing the depressurization process, whether or not wear has occurred is determined based on the amount of change such as strain and acceleration generated in the second link 153 (an example of a link member). In the method of this embodiment, since it is not necessary to compare with the state before wear as in the conventional method, wear can be easily detected. Furthermore, when performing measurements, by providing a strain gauge 156 or an acceleration sensor on the Z-axis positive side of the second link 153 with respect to the toggle mechanism 150, it is possible to diagnose whether or not wear has occurred, thus reducing the burden of diagnosis.

[0158] The embodiments of the injection molding machine monitoring device according to the present invention have been described above, but the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope described in the claims. These also naturally fall within the technical scope of the present invention.

[0159] This application claims priority based on Japanese Patent Application No. 2021-062430, filed on 31 March 2021, and the entire contents of that Japanese Patent Application are incorporated herein by reference. [Explanation of Symbols]

[0160] 10...Injection molding machine 110...Fixed platen 120...Movable platen 150...Toggle mechanism 160...Clamping motor 800...Mold device 152...First link 153...Second link (example of link member) 154...Third link 42A, 43A...Connecting holes 42B, 43B...Bushings 700...Control device 711...Control unit 712...Acquisition unit 713...Determination unit 714...Output unit

Claims

1. An acquisition unit that acquires the amount of change that occurs in the link member based on the detection value in the depressurization process of the detection unit provided on the link member of the toggle mechanism, The system includes a determination unit that determines whether or not wear is occurring in the link member according to the amount of change acquired by the acquisition unit, The amount of change in the link member acquired by the acquisition unit is either the amount of strain in the link member or the acceleration in the link member. Monitoring device for injection molding machines.

2. The determination unit determines whether or not vibration is present according to the acceleration acquired by the acquisition unit, and determines whether or not wear is occurring in the link member according to the presence or absence of vibration. A monitoring device for an injection molding machine according to claim 1.

3. An acquisition unit that acquires the amount of change that occurs in the link member based on the detection value in the depressurization process of the detection unit provided on the link member of the toggle mechanism, The system includes a determination unit that determines whether the amount of change acquired by the acquisition unit exceeds a predetermined threshold, The aforementioned change is the amount of strain generated in the link member, or the acceleration generated in the link member. Monitoring device for injection molding machines.

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