MONITORING DEVICE OF AN INJECTION MOLDING MACHINE

Abstract

Monitoring device (700) of an injection molding machine (10), comprising: a detection unit (712) which detects an amount of change generated at the linking element (153) on the basis of a measured value in a pressure relief process from a detection unit (156) provided at a linking element (153) of a toggle lever mechanism (150); and a determination unit (713) that, in a case after the pressure release has started, an absolute value of the amount of strain detected by the detection unit (712) increases and then gradually decreases, determines whether or not the absolute value exceeds a predetermined threshold value as the absolute value increases.

Description

Technical area

[0001] The present invention relates to a monitoring device of an injection molding machine. State of the art

[0002] In a conventional injection molding machine, a molded product is formed by filling a molding unit with a molding material. The molding unit includes a stationary mold and a movable mold. The movable mold is attached to a movable platen, and a mold support device is arranged to be movable in a mold opening and closing direction. A toggle mechanism that moves the movable platen in the mold opening and closing direction is composed of multiple linkages. When the movable platen moves in the mold opening and closing direction, the multiple linkages also move, and thus a connecting portion of the linkages wears. Summary of the inventionTechnical problem

[0003] In a technique described in JP 2020-62813 A, wear is measured based on the amount of displacement between a position of an element in an initial state before wear and a position of the element at the time of mold closing / clamping. In recent years, however, there has been a need to measure wear of the above-described linking element in a simple manner. EP 1 920 300 B1 discloses a method and apparatus for automatically monitoring repetitive operations of an injection molding machine. JP H09-254 218 A discloses a mold protection device for an injection molding machine. US 2003 / 0 089 179 A1 further discloses a method and apparatus for monitoring irregularities in the mold clamping mechanism of an injection molding machine.

[0004] One aspect of the present invention provides a technique for easily measuring wear by performing measurement based on the amount of change generated in a link member at the time of pressure release in which a mold closing / clamping force decreases. Solution to the problem

[0005] A monitoring device of an injection molding machine according to one aspect of the present invention includes: a detection unit that detects an amount of change generated in a linkage of a toggle mechanism based on a measured value in a pressure-relieving process from a detection unit provided at the linkage of a toggle mechanism; and a determination unit that determines whether or not the absolute value exceeds a predetermined threshold value as the absolute value increases, in a case where, after pressure-relieving has started, an absolute value of the amount of strain detected by the detection unit increases and then gradually decreases.A monitoring unit according to another aspect of the present invention comprises: a detection unit that detects an amount of change generated in a link member of a toggle mechanism based on a measured value in a pressure relief process from a detection unit provided at the link member; and a determination unit that determines whether or not the amount of change detected by the detection unit or a change rate of the amount of change exceeds a predetermined threshold, wherein the determination unit determines whether wear occurs in the link member or a link mechanism when the amount of change or the change rate of the amount of change exceeds the predetermined threshold. Advantageous effects of the invention

[0006] According to the aspect of the present invention, wear of the linking member is easily measured by performing measurement based on the amount of change generated in the linking member. Brief description of the drawings Fig. 1 is a view showing a state in which mold opening is completed in an injection molding machine according to a first embodiment. Fig. 2 is a view showing a state in which mold closing / clamping is performed in the injection molding machine according to the first embodiment. Fig. 3 is a configuration diagram of a toggle mechanism included in the injection molding machine according to the first embodiment. Fig. 4 is a diagram showing a configuration example of a control device according to the first embodiment. Fig. 5 is a diagram showing forces generated in the toggle mechanism in a pressure relief process according to the first embodiment. Fig. 6 is a perspective view showing a shape of a second link according to the first embodiment. Fig. 7 is a front view showing the shape of the second link according to the first embodiment. Fig. 8 is a diagram illustrating a change in the amount of strain detected by a detection unit in the pressure release process of the first embodiment. Fig. 9 is a flowchart showing a flow of a process of determining, via the control device according to the first embodiment, whether or not wear has occurred. Fig. 10 is a diagram illustrating a change in acceleration detected by the detecting unit in the pressure releasing process of the first embodiment. Fig. 11 is a flowchart showing a flow of a process of determining, via the control device according to the first embodiment, whether or not wear has occurred. Description of embodiments

[0007] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same or corresponding reference numerals are assigned to the same or corresponding configurations, and descriptions thereof will be omitted.

[0008] Fig. 1 is a view showing a state in which mold opening is completed in an injection molding machine according to a first embodiment. Fig. 2 is a view showing a state in which mold closing / clamping is performed in the injection molding machine according to the first embodiment. In the present description, an X-axis direction, a Y-axis direction, and a Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction represent a horizontal direction, and the Z-axis direction represents a vertical direction. In a case where a mold closing / clamping unit 100 is of a horizontal type, the X-axis direction represents a mold opening and closing direction, and the Y-axis direction represents a width direction of an injection molding machine 10. A negative side in the Y-axis direction is referred to as an operation side, and a positive side in the Y-axis direction is referred to as a counter-operation side.

[0009] As in Fig. 1 and Fig. As shown in Figure 2, the injection molding machine 10 includes the mold closing / clamping unit 100 that opens and closes a mold unit 800, an ejector unit 200 that ejects a molded product molded by the mold unit 800, an injection unit 300 that injects a molding material into the mold unit 800, a moving unit 400 that causes the injection unit 300 to move back and forth with respect to the mold unit 800, a controller 700 that controls each component of the injection molding machine 10, and a frame 900 that supports each component of the injection molding machine 10. The frame 900 includes a mold closing / clamping unit frame 910 that supports the mold closing / clamping unit 100, and an injection unit frame 920 that supports the injection unit 300. The mold closing / clamping unit frame 910 and the injection unit frame 920 are each installed on a floor 2 via a height adjuster 930.The control device 700 is arranged in an interior space of the injection unit frame 920. Each component of the injection molding machine 10 will be described below. (Mold closing / clamping unit)

[0010] When describing the mold closing / clamping unit 100, a moving direction of a movable platen 120 during mold closing (for example, a positive direction of an X-axis) is defined as forward, and a moving direction of the movable platen 120 during mold opening (for example, a negative direction of the X-axis) is defined as backward.

[0011] The mold closing / clamping unit 100 performs mold closing, pressurizing, closing / clamping, pressure release, and mold opening of the mold unit 800. The mold unit 800 includes a stationary mold 810 and a movable mold 820.

[0012] For example, the mold closing / clamping unit 100 is of a horizontal type, and the mold opening and closing direction is a horizontal direction. The mold closing / clamping unit 100 includes a stationary platen 110 to which the stationary mold 810 is attached, the 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 and closing direction relative to the stationary platen 110.

[0013] The stationary platen 110 is fixed to the mold closing / clamping unit frame 910. The stationary mold 810 is attached to a surface of the stationary platen 110 facing the movable platen 120.

[0014] The movable platen 120 is arranged to be movable in the mold opening and closing direction relative to the mold clamping / clamping unit frame 910. A guide 101 that guides the movable platen 120 is placed on the mold clamping / clamping unit frame 910. The movable mold 820 is attached to a surface of the movable platen 120 facing the stationary platen 110.

[0015] The moving mechanism 102 causes the movable platen 120 to move back and forth with respect to the stationary platen 110 so that mold closing, pressurizing, mold closing / clamping, pressure releasing, and mold opening of the molding unit 800 are performed.The moving mechanism 102 includes a toggle bracket 130 arranged at a distance from the stationary platen 110, a column 140 connecting the stationary platen 110 and the toggle bracket 130, a toggle mechanism 150 moving the movable platen 120 in the mold opening and closing direction with respect to the toggle bracket 130, a mold closing / clamping motor 160 operating the toggle mechanism 150, a motion converting mechanism 170 converting a rotary motion into a linear motion of the mold closing / clamping motor 160, and a mold space adjusting mechanism 180 adjusting a distance between the stationary platen 110 and the toggle bracket 130.

[0016] The toggle lever support 130 is arranged at a distance from the stationary platen 110 and is placed on the mold closing / clamping unit frame 910 so that it is movable in the mold opening and closing direction. The toggle lever support 130 can be arranged so that it is movable along a guide laid on the mold closing / clamping unit frame 910. The guide of the toggle lever support 130 can be common to the guide 101 of the movable platen 120.

[0017] In the present embodiment, the stationary platen 110 is fixed to the mold clamping / clamping unit frame 910, and the toggle bracket 130 is arranged to be movable relative to the mold clamping / clamping unit frame 910 in the mold opening and closing direction. However, the toggle bracket 130 may be fixed to the mold clamping / clamping unit frame 910, and the stationary platen 110 may be arranged to be movable relative to the mold clamping / clamping unit frame 910 in the mold opening and closing direction.

[0018] The column 140 connects the stationary platen 110 and the toggle bracket 130 at a distance L in the mold opening and closing direction. A plurality of (for example, four) columns 140 may be used. The plurality of columns 140 are arranged parallel to each other in the mold opening and closing direction and stretch in accordance with a mold closing / clamping force. At least one of the columns 140 may be provided with a column strain detector 141 that measures a strain of the column 140. The column strain detector 141 transmits a signal indicative of a measurement result thereof to the control device 700. The measurement result of the column strain detector 141 is used in measuring the mold closing / clamping force or the like.

[0019] In the present embodiment, the column strain detector 141 is used as a mold clamping / clamping force detector for measuring the mold clamping / clamping force. However, the present invention is not limited to this. The mold clamping / clamping force detector is not limited to one type of strain gauge. The mold clamping / clamping force detector may be of a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and its mounting position is not limited to the column 140.

[0020] The toggle mechanism 150 is arranged between the movable platen 120 and the toggle beam 130 to connect the movable platen 120 (an example of a first platen) to the stationary platen 110 (an example of a second platen) for mold opening and closing of the molding unit 800. Furthermore, the toggle mechanism 150 moves the movable platen 120 (the example of the first platen) in the mold opening and closing direction with respect to the toggle beam 130. The toggle mechanism 150 includes a crosshead 151 that moves in the mold opening and closing direction and a pair of link groups that are flexed and extended by movement of the crosshead 151. Each of the pair of link groups includes a first link 152 and a second link 153 that are connected to be freely flexed and extended by a pin or the like.The first link 152 is oscillatingly attached to the movable plate 120 by a pin or the like. The second link 153 is oscillatingly attached to the toggle bracket 130 by a pin or the like. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 is caused to move back and forth with respect to the toggle bracket 130, the first link 152 and the second link 153 flex and extend, and the movable plate 120 moves back and forth with respect to the toggle bracket 130.

[0021] A configuration of the toggle mechanism 150 is not shown in Fig. 1 and Fig. 2 shown configurations. In Fig. 1 and Fig. 2, the number of nodes in each link group is, for example, five, but may be four. An end portion of the third link 154 may be connected to the node between the first link 152 and the second link 153.

[0022] The mold closing / clamping motor 160 is mounted on the toggle beam 130 and actuates the toggle mechanism 150. The mold closing / clamping motor 160 causes the crosshead 151 to move forward and backward with respect to the toggle beam 130, so that the first link 152 and the second link 153 flex and extend, and the movable platen 120 moves forward and backward with respect to the toggle beam 130. The mold closing / clamping motor 160 is directly connected to the motion conversion mechanism 170, but may be connected to the motion conversion mechanism 170 via a belt, pulley, or the like.

[0023] The motion conversion mechanism 170 converts the rotary motion of the mold closing / clamping motor 160 into the linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut screwed onto the screw shaft. A ball or roller may be inserted between the screw shaft and the screw nut.

[0024] The mold closing / clamping unit 100 performs a mold closing process, a pressurizing process, a mold closing / clamping process, a pressure releasing process, a mold opening process, and the like under the control of the control device 700.

[0025] During the mold closing process, the mold clamping / clamping motor 160 is driven to cause the crosshead 151 to move forward at a set movement speed to a mold clamping completion position, thereby causing the movable platen 120 to move forward so that the movable mold 820 contacts the stationary mold 810. For example, a position or a movement speed of the crosshead 151 is measured using a mold clamping / clamping motor encoder 161. The mold clamping / clamping motor encoder 161 measures rotation of the mold clamping / clamping motor 160 and transmits a signal indicating a measurement result thereof to the controller 700.

[0026] A crosshead position detector for measuring the position of the crosshead 151 and a crosshead movement speed detector for measuring the movement speed of the crosshead 151 are not limited to the mold clamping / clamping motor encoder 161, and a general detector may be used. Furthermore, a movable platen position detector for measuring a position of the movable platen 120 and a movable platen movement speed detector for measuring a movement speed of the movable platen 120 are not limited to the mold clamping / clamping motor encoder 161, and a general detector may be used.

[0027] In the pressurizing process, the mold closing / clamping motor 160 is further driven to cause the crosshead 151 to further move forward from the mold closing completion position to a mold closing / clamping position, thereby generating a mold closing / clamping force.

[0028] During the mold closing / clamping process, the mold closing / clamping motor 160 is driven to maintain the position of the crosshead 151 at the mold closing / clamping position. During the mold closing / clamping process, the mold closing / clamping force generated during the pressurization process is maintained. During the mold closing / clamping process, a cavity space 801 (see Fig. 2) is formed between the movable mold 820 and the stationary mold 810, and the injection unit 300 fills the cavity 801 with a liquid molding material. A molded product is obtained by solidifying the molding material filled therein.

[0029] The number of cavity spaces 801 may be one or more. In the latter case, a plurality of molded products can be obtained simultaneously. A feed material may be arranged in one portion of the cavity space 801, and the other portion of the cavity space 801 may be filled with the molding material. A molded product in which the feed material and the molding material are integrated with each other can be obtained.

[0030] During the pressure release process, the mold closing / clamping motor 160 is driven to cause the crosshead 151 to move backward from the mold closing / clamping position to a mold opening start position, so that the movable platen 120 moves backward to reduce the mold closing / clamping force. The mold opening start position and the mold closing end position may be the same position.

[0031] During the mold opening process, the mold closing / clamping motor 160 is driven to cause the crosshead 151 to move backward at a set moving speed from the mold opening start position to a mold opening completion position, so that the movable platen 120 moves backward and the movable mold 820 is separated from the stationary mold 810. Thereafter, the ejector unit 200 ejects the molded product from the movable mold 820.

[0032] Setting conditions in the mold clamping process, the pressurizing process, and the mold clamping / clamping process are collectively set as a series of setting conditions. For example, the moving speed or positions (including a mold clamping start position, a moving speed switching position, the mold clamping completion position, and the mold clamping / clamping position) of the crosshead 151 and the mold clamping / clamping force in the mold clamping process and the pressurizing process are collectively set as a series of setting conditions. The mold clamping start position, the moving speed switching position, the mold clamping completion position, and the mold clamping / clamping position are arranged in this order from a back side to a front side and represent a starting point and an ending point of a section in which the moving speed is set.The movement speed is set for each section. The number of movement speed switching positions can be one or more. The movement speed switching position may not be set. Only one of the mold closing / clamping position and the mold closing / clamping force may be set.

[0033] Setting conditions in the pressure release process and the mold opening process are set in the same way. For example, the movement speed or the positions (the mold opening start position, the movement speed switching position, and the mold opening completion position) of the crosshead 151 in the pressure release process and the mold opening process are collectively set as a series of setting conditions. The mold opening start position, the movement speed switching position, and the mold opening completion position are arranged in this order from the front to the back and represent the start point and end point of the section in which the movement speed is set. The movement speed is set for each section. The number of movement speed switching positions can be one or more.The movement speed switching position may not be set. The mold opening start position and the mold closing completion position may be the same position. Furthermore, the mold opening completion position and the mold closing start position may be the same position.

[0034] Instead of the movement speed, positions, and the like of the crosshead 151, the movement speed, positions, and the like of the movable platen 120 may be set. Furthermore, instead of the position (e.g., the mold closing / clamping position) of the crosshead or the position of the movable platen, the mold closing / clamping force may be set.

[0035] The toggle mechanism 150 amplifies a driving force of the mold closing / clamping motor 160 and transmits the driving force to the movable platen 120. This amplification magnification is referred to as a toggle magnification. The toggle magnification is changed according to an angle θ (hereinafter also referred to as a "link angle θ") formed between the first link 152 and the second link 153. The link angle θ is obtained from the position of the crosshead 151. When the link angle θ is 180°, the toggle magnification is maximized.

[0036] In a case where a mold space of the molding unit 800 is changed due to replacement of the molding unit 800, a temperature change in the molding unit 800, or the like, mold space adjustment is performed so that a predetermined mold closing / clamping force is obtained during mold closing / clamping. For example, in the mold space adjustment, the distance L between the stationary platen 110 and the toggle bracket 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at a mold contact time at which the movable mold 820 contacts the stationary mold 810.

[0037] The mold closing / clamping unit 100 includes the mold space adjustment mechanism 180. The mold space adjustment mechanism 180 performs the mold space adjustment by adjusting the distance L between the stationary platen 110 and the toggle bracket 130. For example, a time for the mold space adjustment is determined from an end point of one molding cycle to a start point of a subsequent molding cycle. The mold space adjustment mechanism 180 includes, for example, a screw shaft 181 formed in a rear end portion of the column 140, a screw nut 182 supported by the toggle bracket 130 so as to be rotatable and not move back and forth, and a mold space adjustment motor 183 that rotates the screw nut 182 screwed onto the screw shaft 181.

[0038] The spindle shaft 181 and the spindle nut 182 are provided for each of the columns 140. A rotational drive force of the mold space adjustment motor 183 can be transmitted to a plurality of the spindle nuts 182 via a rotational drive force transmission unit 185. The plurality of spindle nuts 182 can be rotated synchronously with each other. The plurality of spindle nuts 182 can be rotated individually by changing a transmission channel of the rotational drive force transmission unit 185.

[0039] The rotary drive force transmission unit 185 is configured, for example, to include a gear. In this case, a driven gear is formed on an outer periphery of each spindle nut 182, a driving gear is mounted on an output shaft of the mold space adjustment motor 183, and a plurality of intermediate gears meshing with the driven gear and the driving gear are rotatably supported in a central portion of the toggle bracket 130. The rotary drive force transmission unit 185 may be configured to include a belt, a pulley, or the like instead of the gear.

[0040] The operation of the mold space adjustment mechanism 180 is controlled by the controller 700. The controller 700 drives the mold space adjustment motor 183 to rotate the spindle nut 182. As a result, a position of the toggle bracket 130 relative to the column 140 is adjusted, and the distance L between the stationary platen 110 and the toggle bracket 130 is adjusted. Furthermore, several of the mold space adjustment mechanisms can be used in combination.

[0041] The distance L is measured using a mold space adjustment motor encoder 184. The mold space adjustment motor encoder 184 measures a rotation amount or rotation direction of the mold space adjustment motor 183 and transmits a signal indicating a measurement result thereof to the controller 700. The measurement result of the mold space adjustment motor encoder 184 is used in monitoring or controlling the position or distance L of the toggle beam 130. A toggle beam position detector for measuring the position of the toggle beam 130 and a distance detector for measuring the distance L are not limited to the mold space adjustment motor encoder 184, and a general detector can be used.

[0042] The mold closing / clamping unit 100 may include a mold temperature controller that adjusts a temperature of the mold unit 800. The mold unit 800 has a flow path of a temperature control medium inside. The mold temperature controller adjusts the temperature of the mold unit 800 by adjusting a temperature of the temperature control medium supplied to the flow path of the mold unit 800.

[0043] The mold closing / clamping unit 100 of the present embodiment is of the horizontal type in which the mold opening and closing direction is the horizontal direction, but may be of a vertical type in which the mold opening and closing direction is an up-down direction.

[0044] The mold closing / clamping unit 100 of the present embodiment includes the mold closing / clamping motor 160 as a drive source. However, a hydraulic cylinder may be provided instead of the mold closing / clamping motor 160. Furthermore, the mold closing / clamping unit 100 may include a linear motor for mold opening and closing, and it may include an electromagnet for mold closing / clamping. (ejector unit)

[0045] When describing the ejector unit 200, similarly to the description of the mold closing / clamping unit 100, a moving direction of the movable platen 120 during mold closing (for example, the positive direction of the X-axis) is defined as forward, and a moving direction of the movable platen 120 during mold opening (for example, the negative direction of the X-axis) is defined as reverse.

[0046] The ejector unit 200 is attached to the movable platen 120 and moves back and forth along with the movable platen 120. The ejector unit 200 includes an ejector rod 210 that ejects a molded product from the molding unit 800, and a drive mechanism 220 that moves the ejector rod 210 in the moving direction (X-axis direction) of the movable platen 120.

[0047] The ejector rod 210 is arranged to move back and forth within a through hole of the movable platen 120. A front end portion of the ejector rod 210 contacts an ejector plate 826 of the movable mold 820. The front end portion of the ejector rod 210 may or may not be connected to the ejector plate 826.

[0048] The drive mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts a rotary motion of the ejector motor into a linear motion of the ejector rod 210. The motion conversion mechanism includes a spindle shaft and a spindle nut screwed onto the spindle shaft. A ball or roller can be inserted between the spindle shaft and the spindle nut.

[0049] The ejector unit 200 performs an ejection process under the control of the controller 700. During the ejection process, the ejector rod 210 is caused to move forward from a standby position to an ejection position at a set movement speed, so that the ejector plate 826 moves forward to eject the molded product. Thereafter, the ejector motor is driven to cause the ejector rod 210 to move backward at a set movement speed, so that the ejector plate 826 moves backward to an original standby position.

[0050] For example, a position or a movement speed of the ejector rod 210 is measured using an ejector motor encoder. The ejector motor encoder measures the rotation of the ejector motor and transmits a signal indicating a measurement result thereof to the controller 700. An ejector rod position detector for measuring the position of the ejector rod 210 and an ejector rod movement speed detector for measuring the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and a general detector can be used. (injection unit)

[0051] When describing the injection unit 300, unlike the description of the mold closing / clamping unit 100 or the description of the ejector unit 200, a moving direction of a screw 330 during filling (for example, the negative direction of the X-axis) is defined as forward, and a moving direction of the screw 330 during plasticizing (for example, the positive direction of the X-axis) is defined as reverse.

[0052] The injection unit 300 is mounted on a slide base 301, and the slide base 301 is arranged to move forward and backward relative to the injection unit frame 920. The injection unit 300 is arranged to move forward and backward relative to the mold unit 800. The injection unit 300 contacts the mold unit 800 and fills the cavity 801 in the mold unit 800 with the molding material.The injection unit 300 includes, for example, a cylinder 310 that heats the molding material, a nozzle 320 provided in a front end portion of the cylinder 310, the screw 330 that is arranged to move back and forth and rotate inside the cylinder 310, a plasticizing motor 340 that rotates the screw 330, an injection motor 350 that causes the screw 330 to move back and forth, and a load detector 360 that measures a load transmitted between the injection motor 350 and the screw 330.

[0053] The cylinder 310 heats the molding material supplied from a supply port 311 into the cylinder 310. The molding material contains, for example, a resin. The molding material is formed, for example, in a pellet shape and is supplied to the supply port 311 in a solid state. The supply port 311 is formed in a rear portion of the cylinder 310. A cooler 312, such as a water-cooled cylinder, is provided on an outer periphery of the rear portion of the cylinder 310. A heating unit 313, such as a band heater, and a temperature measuring device 314 are provided in front of the cooler 312 on an outer periphery of the cylinder 310.

[0054] The cylinder 310 is divided into a plurality of zones in an axial direction (e.g., the X-axis direction) of the cylinder 310. The heating unit 313 and the temperature measuring device 314 are provided in each of the plurality of zones. The control device 700 controls the heating unit 313 so that a set temperature is set in each of the plurality of zones and a measurement temperature of the temperature measuring device 314 reaches the set temperature.

[0055] The nozzle 320 is provided in the front end portion of the cylinder 310 and is pressed against the molding unit 800. The heating unit 313 and the temperature measuring device 314 are provided on an outer periphery of the nozzle 320. The control device 700 controls the heating unit 313 so that a measuring temperature of the nozzle 320 reaches the set temperature.

[0056] The screw 330 is arranged to rotate and move back and forth inside the cylinder 310. As the screw 330 rotates, the molding material is conveyed forward along a spiral groove of the screw 330. The molding material is gradually melted by heat from the cylinder 310 as it is conveyed forward. When the liquid molding material is conveyed to the front of the screw 330 and accumulated in a front portion of the cylinder 310, the screw 330 moves backward. Thereafter, when the screw 330 is caused to move forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and fills an interior of the molding unit 800.

[0057] As a backflow prevention valve for preventing backflow of the molding material fed backward from the front of the screw 330 when the screw 330 is pushed forward, a backflow prevention ring 331 is attached to a front portion of the screw 330 so as to be able to move forward and backward.

[0058] When the screw 330 is caused to move forward, the backflow prevention ring 331 is pushed backward by a pressure of the molding material in front of the screw 330 and moves backward relative to the screw 330 to a closing position (see Fig. 2), where a flow path of the molding material is closed. Accordingly, the molding material accumulated in front of the screw 330 is prevented from flowing backward.

[0059] 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 conveyed forward along the spiral groove of the screw 330 and moves forward relative to the screw 330 to an opening position (see Fig. 1), where the flow path of the molding material is open. Accordingly, the molding material is conveyed to the front of the screw 330.

[0060] The backflow prevention ring 331 may be either a co-rotating type that rotates together with the screw 330 or a non-rotating type that does not rotate together with the screw 330.

[0061] The injection unit 300 may include a drive source that causes the backflow prevention ring 331 to move back and forth with respect to the screw 330 between the open position and the close position.

[0062] The plasticizing motor 340 rotates the screw 330. A drive source that rotates the screw 330 is not limited to the plasticizing motor 340 and may be, for example, a hydraulic pump.

[0063] The injection motor 350 causes the screw 330 to move back and forth. A motion conversion mechanism that converts a rotational motion of the injection motor 350 into a linear motion of the screw 330 or the like is provided between the injection motor 350 and the screw 330. The motion conversion mechanism includes, for example, a screw shaft and a screw nut screwed onto the screw shaft. A ball or a roller may be provided between the screw shaft and the screw nut. The drive source that causes the screw 330 to move back and forth is not limited to the injection motor 350 and may be, for example, a hydraulic cylinder.

[0064] The load detector 360 measures a load transmitted between the injection motor 350 and the screw 330. The measured load is converted into a pressure by the control device 700. The load detector 360 is provided in a load transmission channel between the injection motor 350 and the screw 330 and measures the load acting on the load detector 360.

[0065] The load detector 360 transmits a signal of the measured load to the control device 700. The load measured by the load detector 360 is converted into the pressure acting between the screw 330 and the molding material and is used in controlling or monitoring the pressure received by the screw 330 from the molding material, a back pressure against the screw 330, the pressure acting from the screw 330 on the molding material, or the like.

[0066] A pressure detector for measuring the pressure of the molding material is not limited to the load detector 360, and a general detector can be used. For example, a nozzle pressure sensor or a mold cavity pressure sensor can be used. The nozzle pressure sensor is installed in the nozzle 320. The mold cavity pressure sensor is installed inside the molding unit 800.

[0067] The injection unit 300 performs a plasticizing process, a filling process, a pressure-holding process, and the like under the control of the control device 700. The filling process and the pressure-holding process may be collectively referred to as an injection process.

[0068] During the plasticizing process, the plasticizing motor 340 is driven to rotate the screw 330 at a set speed, so that the molding material is conveyed forward along the spiral groove of the screw 330. As a result, the molding material is gradually melted. As the liquid molding material is conveyed to the front of the screw 330 and accumulated in the front portion of the cylinder 310, the screw 330 moves backward. The rotational speed of the screw 330 is measured, for example, by using a plasticizing motor encoder 341. The plasticizing motor encoder 341 measures the rotation of the plasticizing motor 340 and transmits a signal indicating a measurement result thereof to the control device 700. A screw speed detector for measuring the rotational speed of the screw 330 is not limited to the plasticizing motor encoder 341, and a general detector can be used.

[0069] During the plasticizing process, the injection motor 350 can be driven to apply a set back pressure to the screw 330 to limit sudden backward movement of the screw 330. The back pressure applied to the screw 330 is measured, for example, using the load detector 360. When the screw 330 moves backward to a plasticizing completion position and a predetermined amount of molding material is accumulated in front of the screw 330, the plasticizing process is completed.

[0070] The position in the movement direction and the rotational speed of the screw 330 in the plasticizing process are collectively set as a series of setting conditions. For example, a plasticizing start position, a speed switching position, and the plasticizing completion position are set. These positions are arranged in this order from the front to the back and represent a starting point and an end point of a section in which the rotational speed is set. The rotational speed is set for each section. The number of speed switching positions can be one or more. The speed switching position may not be set. In addition, the back pressure is set for each section.

[0071] During the filling process, the injection motor 350 is driven to cause the screw 330 to move forward at a set moving speed, and the cavity space 801 within the molding unit 800 is filled with the liquid molding material accumulated in front of the screw 330. The position or moving speed of the screw 330 is measured, for example, by using an injection motor encoder 351. The injection motor encoder 351 measures the rotation of the injection motor 350 and transmits a signal indicating a measurement result thereof to the controller 700. When the position of the screw 330 reaches a set position, the filling process is switched to the pressure-holding process (so-called V / P switching). The position at which the V / P switching is performed is referred to as a V / P switching position.The set moving speed of the screw 330 can be changed in accordance with the position, time, or the like of the screw 330.

[0072] The position and movement speed of the screw 330 during the filling process are collectively set as a series of setting conditions. For example, a filling start position (also referred to as an "injection start position"), the movement speed switching position, and the V / P switching position are set. These positions are arranged in this order from the back to the front and represent the starting point and end point of the section in which the movement speed is set. The movement speed is set for each section. The number of movement speed switching positions can be one or more. The movement speed switching position may not be set.

[0073] For each section where the movement speed of the screw 330 is set, an upper limit of the pressure of the screw 330 is set. The pressure of the screw 330 is measured by the load detector 360. In a case where the pressure of the screw 330 is equal to or lower than a set pressure, the screw 330 moves forward at a set movement speed. On the other hand, in a case where the pressure of the screw 330 exceeds the set pressure, in order to protect the mold, the screw 330 is caused to move forward at a movement speed slower than the set movement speed so that the pressure of the screw 330 is equal to or lower than the set pressure.

[0074] After the position of the screw 330 reaches the V / P switching position in the filling process, 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 caused to move forward at a low speed, or it may be caused to move backward at a low speed. Furthermore, a screw position detector for measuring the position of the screw 330 and a screw movement speed detector for measuring the movement speed of the screw 330 are not limited to the injection motor encoder 351, and a general detector may be used.

[0075] In the pressure-holding process, the injection motor 350 is driven to push the screw 330 forward. A pressure (hereinafter also referred to as a "holding pressure") of the molding material in a front end portion of the screw 330 is maintained at a set pressure, and the molding material remaining within the cylinder 310 is pushed toward the molding unit 800. An insufficient amount of the molding material due to cooling shrinkage inside the molding unit 800 can be replenished. The holding pressure is measured, for example, by using the load detector 360. A set value of the holding pressure can be changed depending on an elapsed time since the start of the pressure-holding process, or the like. A plurality of holding pressures and a plurality of holding times for holding the holding pressures in the pressure-holding process can be set respectively, or they can be set collectively as a series of setting conditions.

[0076] During the pressure-holding process, the molding material in the cavity 801 within the molding unit 800 is gradually cooled. When the pressure-holding process is completed, an inlet of the cavity 801 is closed by the solidified molding material. This state is called gate sealing and prevents the backflow of the molding material from the cavity 801. After the pressure-holding process, a cooling process starts. During the cooling process, the molding material within the cavity 801 is solidified. To shorten a molding cycle time, the plasticizing process can be performed during the cooling process.

[0077] The injection unit 300 of the present embodiment is of an in-line screw type, but may be of a pre-plasticizing type. The pre-plasticizing type injection unit supplies the molding material molten within a plasticizing cylinder to an injection cylinder, and the molding material is injected from the injection cylinder into the molding unit. Inside the plasticizing cylinder, the screw is arranged so that it is rotatable and cannot move back and forth, or the screw is arranged so that it is rotatable and can move back and forth. Meanwhile, a plunger is arranged so that it can move back and forth inside the injection cylinder.

[0078] Furthermore, the injection unit 300 of the present embodiment is of a horizontal type in which the axial direction of the cylinder 310 is a horizontal direction, but may be of a vertical type in which the axial direction of the cylinder 310 is an up-down direction. The mold closing / clamping unit combined with a vertical-type injection unit 300 may be of the vertical type or the horizontal type. Similarly, the mold closing / clamping unit combined with a horizontal-type injection unit 300 may be of the horizontal type or the vertical type. (movement unit)

[0079] When describing the moving unit 400, similarly to the description of the injection unit 300, a moving direction of the screw 330 during filling (for example, the negative direction of the X-axis) is defined as forward, and a moving direction of the screw 330 during plasticizing (for example, the positive direction of the X-axis) is defined as backward.

[0080] The moving unit 400 causes the injection unit 300 to move back and forth with respect to the molding unit 800. The moving unit 400 presses the nozzle 320 against the molding unit 800, thereby generating a nozzle contact pressure. The moving unit 400 includes a hydraulic pump 410, a motor 420 serving as a drive source, a hydraulic cylinder 430 serving as a hydraulic actuator, and the like.

[0081] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectional pump that switches the rotational directions of the motor 420, so that a hydraulic fluid (e.g., oil) is sucked in from any one of the first port 411 and the second port 412 and discharged from the other to generate hydraulic pressure. The hydraulic pump 410 can suck the hydraulic fluid from a tank and discharge the hydraulic fluid from the first port 411 or the second port 412.

[0082] The motor 420 drives the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 in a rotational direction and with a torque in accordance with a control signal transmitted from the controller 700. The motor 420 may be an electric motor or may be an electric servomotor.

[0083] The hydraulic cylinder 430 includes a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is attached to the injection unit 300. The piston 432 divides an inner surface of the cylinder body 431 into a front chamber 435, which serves as a first chamber, and a rear chamber 436, which serves as a second chamber. The piston rod 433 is attached to the stationary plate 110.

[0084] The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via a first flow path 401. The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 via the first flow path 401, thereby pushing the injection unit 300 forward. The injection unit 300 moves forward, and the nozzle 320 is pressed against the stationary mold 810. The front chamber 435 functions as a pressure chamber that generates the nozzle contact pressure of the nozzle 320 using the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0085] On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via a second flow path 402. The hydraulic fluid discharged from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402, thereby pushing the injection unit 300 backward. The injection unit 300 moves backward, and the nozzle 320 is separated from the stationary mold 810.

[0086] In the present embodiment, the movement unit 400 includes the 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 a rotational motion of the electric motor into a linear motion of the injection unit 300 may be used. (control device)

[0087] For example, the control device 700 is configured to include a computer and, as shown in Fig. 1 and Fig. 2, a central processing unit (CPU) 701, a storage medium 702 such as a memory, an input interface 703, and an output interface 704. The control device 700 performs various types of control by causing the CPU 701 to execute a program stored in the storage medium 702. Furthermore, the control device 700 receives a signal from the outside through the input interface 703 and transmits the signal to the outside through the output interface 704.

[0088] The control device 700 repeatedly performs the plasticizing process, the mold closing process, the pressurizing process, the mold closing / clamping process, the filling process, the pressure holding process, the cooling process, the pressure releasing process, the mold opening process, the ejection process, and the like, thereby repeatedly producing the molded product. A series of operations for obtaining the molded product, for example, an operation from the start of the plasticizing process to the start of the subsequent plasticizing process, is referred to as a "shot" or a "molding cycle." Furthermore, a time required for one shot is referred to as a "molding cycle time" or a "cycle time."

[0089] For example, a molding cycle includes the plasticizing process, the mold closing process, the pressurization process, the mold closing / clamping process, the filling process, the pressure holding process, the cooling process, the pressure release process, the mold opening process, and the ejection process, in this order. The sequence described here is the order of the start times of the respective processes. The filling process, the pressure holding process, and the cooling process are performed during the mold closing / clamping process. The start of the mold closing / clamping process can coincide with the start of the filling process. The completion of the pressure release process coincides with the start of the mold opening process.

[0090] Multiple processes can be performed simultaneously to shorten the molding cycle time. For example, the plasticizing process may be performed during the cooling process of the previous molding cycle, or it may be performed during the mold closing / clamping process. In this case, the mold closing process may be performed at an initial stage of the molding cycle. Moreover, the filling process may start during the mold closing process. Furthermore, the ejection process may start during the mold opening process. In a case where an on-off valve is provided for opening and closing a flow path of the nozzle 320, the mold opening process may start during the plasticizing process. The reason is as follows. Even in a case where the mold opening process starts during the plasticizing process, the molding material will not discharge from the nozzle 320 if the on-off valve closes the flow path of the nozzle 320.

[0091] A molding cycle may include a process other than the plasticizing process, the mold closing process, the pressurizing process, the mold closing / clamping process, the filling process, the pressure holding process, the cooling process, the pressure releasing process, the mold opening process, and the ejection process.

[0092] For example, after the pressure-holding process is completed and before the plasticizing process begins, a pre-plasticizing suction-back process of causing the screw 330 to move backward to a preset plasticizing start position can be performed. The pressure of the molding material accumulated in front of the screw 330 before the start of the plasticizing process can be reduced, and a sudden backward movement of the screw 330 at the start of the plasticizing process can be prevented.

[0093] Furthermore, after the plasticizing process is completed and before the filling process begins, a post-plasticizing suction process can be performed, in which the screw 330 is caused to move backward to the preset filling start position (also referred to as the "injection start position"). The pressure of the molding material accumulated in front of the screw 330 before the start of the filling process can be reduced, and leakage of the molding material from the nozzle 320 before the start of the filling process can be prevented.

[0094] The control device 700 is connected to an operation device 750 that receives a user's input operation, and to a display device 760 that displays a screen. For example, the operation device 750 and the display device 760 may be integrated with each other in a form of a touch panel 770. The touch panel 770, which serves as the display device 760, displays the screen under the control of the control device 700. The screen of the touch panel 770 may display, for example, settings of the injection molding machine 10 and information regarding a current state of the injection molding machine 10. Furthermore, the screen of the touch panel 770 may display, for example, a button for accepting the user's input operation or an operation section such as an input field.The touch panel 770 serving as the operation device 750 detects a user's input operation on the screen and outputs a signal corresponding to the input operation to the control device 700. In this way, for example, while checking information displayed on the screen, the user can perform adjustment (including input of a setting value) of the injection molding machine 10 by operating the operation section provided on the screen. Furthermore, the user can operate the injection molding machine 10 corresponding to the operation section by operating the operation section provided on the screen. For example, the operation of the injection molding machine 10 may be an operation (including stopping) of the mold closing / clamping unit 100, the ejector unit 200, the injection unit 300, the moving unit 400, or the like.In addition, the operation of the injection molding machine 10 may be switching between the screens displayed on the touch panel 770 serving as the display device 760.

[0095] A case where the operation device 750 and the display device 760 of the present embodiment are integrated with each other as the touch panel 770 has been described. However, these two may be provided independently. Furthermore, a plurality of the operation devices 750 may be provided. The operation device 750 and the display device 760 are arranged on the operation side (a negative direction of the Y-axis) of the mold closing / clamping unit 100 (more specifically, the stationary platen 110). (Configuration of toggle mechanism)

[0096] Next, a configuration of the toggle mechanism 150 will be described. Fig. 3 is a configuration diagram of the toggle mechanism 150 included in the injection molding machine 10 according to the first embodiment.

[0097] As in Fig. 3, a link connecting portion 131 of the toggle lever support 130 is connected to the second link 153 by a second connecting mechanism 42. A connecting pin 51 is used for connection by the second connecting mechanism 42. The connecting pin 51 is fixed to a connecting hole of the link connecting portion 131 of the toggle lever support 130 in a non-rotatable manner and can be inserted into a connecting hole 42A (see Fig. 7) of the second connecting link 153 pressed-in bushing 42B (see Fig. 7). A sliding surface between the bushing 42B and the connecting pin 51 is lubricated.

[0098] The first link 152 and the second link 153 are connected to each other by a third connection mechanism 43. A connection pin 52 is used for connection by the third connection mechanism 43. The connection pin 52 is fixed to a connection hole of the first link 152 in a non-rotatable manner and can be inserted into a connection hole 43A (see Fig. 7) of the second link 153, which is the other connecting element, press-fitted bushing 43B (see Fig. 7). A sliding surface between the bushing 43B and the connecting pin 52 is lubricated.

[0099] Similarly, in link mechanisms (a first link mechanism 41, a fourth link mechanism 44, and a fifth link mechanism 45) described later, the link pins 50, 53, and 54 are respectively fixed to one set of links in a non-rotatable manner and can slide on bushings press-fitted into the other set of links. Sliding surfaces between the bushings and the link pins 50, 53, and 54 are lubricated.

[0100] A link connecting portion 121 of the movable plate 120 is connected to the first link 152 through the first link mechanism 41. The connecting pin 50 is used for connection through the first link mechanism 41.

[0101] The crosshead 151 is connected to the third link 154 by the fourth link mechanism 44. The connecting pin 53 is used for the connection by the fourth link mechanism 44. The third link 154 is connected to the second link 153 on a substantially positive direction side of the Z-axis by the fifth link mechanism 45. The connecting pin 54 is used for the connection by the fifth link mechanism 45.

[0102] During each process of mold clamping, pressurizing, mold closing / clamping, pressure release, and mold opening, the crosshead 151 is moved in the X-axis direction by a thrust force generated by driving the mold closing / clamping motor 160. 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 around the second link mechanism 42 so as to arc on an XZ-axis plane. Accordingly, the first link 152 and the second link 153 are flexed and extended, and the movable platen 120 moves back and forth with respect to the toggle bracket 130.

[0103] The second link 153 of the present embodiment is provided with a strain gauge 156 on a side surface on the substantially positive direction side of the Z-axis. A signal generated by the strain gauge 156 is transmitted to the control device 700. The control device 700 then determines, via the signal from the strain gauge 156, whether or not wear has occurred in the link mechanisms connected to the second link 153 (for example, the second link mechanism 42 and the third link mechanism 43).

[0104] Fig. 4 is a diagram showing a configuration example of the control device 700 according to the present embodiment. As shown in Fig. 4, the Fig. 4 is realized by the CPU 701 provided in the control device 700. In addition, the configuration shown in Fig. 4 may be realized by hardware connection, may be realized by software control, or may be realized by a combination of hardware connection and software control.

[0105] As in Fig. As shown in Figure 4, the control device 700 includes a control unit 711, a detection unit 712, a determination unit 713, and an output unit 714.

[0106] The control unit 711 controls the mold clamping / clamping motor 160 during each process of mold clamping, pressurizing, mold closing / clamping, pressure release, and mold opening. For example, during the pressure release process, the control unit 711 drives and controls the mold clamping / clamping motor 160 to cause the crosshead 151 to move backward from the mold closing / clamping position to the mold opening start position.

[0107] The detection unit 712 detects the amount of strain generated at the second link 153 (an example of the amount of change) based on the signal (measured value) in the pressure release process from the strain gauge 156 (an example of a detection unit) provided at the second link 153 (an example of a linking element). In the present embodiment, it is determined whether wear has occurred according to the amount of strain detected in the pressure release process. Therefore, the strain generated at the second link 153 of the present embodiment will be described.

[0108] Fig. 5 is a diagram showing forces generated in the toggle mechanism 150 in the pressure relief process according to the first embodiment. As shown in Fig. As shown in Figure 5, the thrust force generated by driving the mold closing / clamping motor 160 generates a force 1501 to move the crosshead 151 in the negative direction of the X-axis. Via the movement of the crosshead 151 in the negative direction of the X-axis, the third link 154 connected by the fourth link mechanism 44 also begins to move in the negative direction of the X-axis.

[0109] The second link 153 is also connected to the third link 154 through the fifth link mechanism 45 provided on a substantially negative direction side of the Z-axis. Therefore, when the third link 154 moves, a force 1502 is generated to move the second link 153 around the second link mechanism 42 to the substantially negative direction side of the Z-axis where the third link 154 is present. In a case where wear has occurred in the third link mechanism 43, when the second link 153 moves in response to the force 1502, friction occurs between the second link 153 and the connecting pin 52 in the third link mechanism 43, and a force 1503 is generated.

[0110] During a normal pressure release process, the mold closing / clamping force decreases, so the strain generated at the second link 153 decreases. However, in a case where wear has occurred in the link mechanism, such as the third link mechanism 43, a force in a direction opposite to the force 1502 is generated by the link mechanism, so the strain generated at the second link 153 increases. Therefore, in the present embodiment, it is determined whether wear has occurred based on whether the strain increases during the pressure release process.

[0111] Fig. Fig. 6 is a perspective view showing a shape of the second link 153 according to the present embodiment, and Fig. 7 is a front view showing the shape of the second link 153 according to the present embodiment.

[0112] The Fig. 6 and Fig. The second link 153 shown in FIG. 7 is formed from a single piece. The second link 153 of the present embodiment is one of a plurality of links (an example of a plurality of linking elements) constituting the toggle mechanism 150, and includes the connecting hole 42A (an example of a first connecting portion) for constituting the second link mechanism 42 and the connecting hole 43A (an example of the first connecting portion) for constituting the third link mechanism 43 for connecting the stationary platen 110 (a second platen) and the movable platen 120 (a first platen).

[0113] In the second link 153, the connecting hole 42A and the connecting hole 43A are formed such that distances L1 from a center 42C of the connecting hole 42A and a center 43C of the connecting hole 43A to side surfaces in a substantially positive direction of the Z-axis and distances L1 to side surfaces in a substantially negative direction of the Z-axis are equal to each other.

[0114] Furthermore, the second link 153 of the present embodiment has a connection hole 45A (an example of a second connection portion) constituting the fifth connection mechanism 45 for transmitting the mold closing / clamping force from the mold closing / clamping motor 160 (an example of a drive source) to the molding unit 800.

[0115] A center 45C of the connection hole 45A is located substantially at the center with respect to a length of the second link 153 in the X-axis direction. Furthermore, the center 45C of the connection hole 45A is located at a position closer to a negative direction side of the Z-axis. Accordingly, the second link 153 can be connected to the third link 154 located in the negative direction of the Z-axis.

[0116] The bushing 42B is fitted into the connecting hole 42A of the second link 153 by using shrinkage fitting. Since the bushing 42B has the sliding surface on an inner side thereof, the bushing 42B functions as a bearing of the connecting pin 51 provided to be in contact with the inner side.

[0117] Similarly, the bushing 43B is fitted into the connecting hole 43A of the second link 153 by using shrinkage fitting. Since the bushing 43B has the sliding surface on an inner side thereof, the bushing 43B functions as a bearing of the connecting pin 52 provided to be in contact with the inner side.

[0118] For example, in a case where the bushing 43B is worn, a friction coefficient of the sliding surface increases. Accordingly, when the force 1502 in the negative direction of the Z-axis is generated by the third link 154 at the connecting hole 45A constituting the fifth link mechanism 45, in a case where sliding is reduced by the friction occurring within the bushing 43B, the force 1503 is generated in the positive direction of the Z-axis.

[0119] Furthermore, in a case where the bushing 42B is worn, a friction coefficient of the sliding surface increases. Accordingly, when the force 1502 is generated in the negative direction of the Z-axis at the connecting hole 45A constituting the fifth connecting mechanism 45, in a case where sliding is reduced by the friction occurring within the bushing 42B, a force 1504 is generated in the positive direction of the Z-axis.

[0120] Due to these forces, strain is generated in each of a region 601, a region 602, and a region 603 of side surfaces present on a positive direction side of the Z-axis of the second link 153. Therefore, in the control device 700 of the present embodiment, the strain generated in any of these regions 601 to 603 is measured to determine whether or not wear has occurred. In the present embodiment, an example in which the strain gauge 156 (an example of the detection unit) is provided in the region 602 has been described. However, the strain may be measured in the other regions 601 and 603 to determine whether or not wear has occurred.

[0121] Back to Fig. 4, the determination unit 713 determines whether or not the amount of strain detected by the detection unit 712 exceeds a predetermined threshold value T1.

[0122] Fig. Fig. 8 is a graph illustrating a change in the amount of strain detected by the detection unit 712 in the pressure release process of the present embodiment. Fig. In the example shown in Figure 8, a horizontal axis indicates a lapse of time, and a time "0" represents the time at which pressure release begins. A vertical axis indicates the amount of elongation and the mold closing / clamping force.

[0123] As in Fig. As shown in Figure 8, after pressure release has begun, the mold closing / clamping force 1801 decreases over time and approaches a mold closing / clamping force of “0”.

[0124] In the Fig. In the example shown in Figure 8, a change 1802 in the amount of elongation in a case where no wear has occurred and a change 1803 in the amount of elongation when wear has occurred are shown. Fig. In the example shown in Figure 8, at the time pressure release began, strain was already generated due to the mold closing / clamping force in the mold closing / clamping process. In the case where no wear occurred, as indicated by the change 1802 in the amount of strain, the amount of strain approaches a strain amount of "0" after a predetermined time has elapsed.

[0125] On the other hand, in the case where wear has occurred, as indicated by the change 1803 in the amount of strain after the pressure release begins, an absolute value of the amount of strain increases and then gradually decreases. In the present embodiment, the threshold value T1 (absolute value) is set as a criterion for determining whether or not wear has occurred.

[0126] Therefore, since the absolute value of the amount of strain at a time t1 becomes larger than the threshold value T1, the determination unit 713 determines that at least one of the bushings 42B and 43B of the second link 153 is worn.

[0127] Furthermore, in the present embodiment, an example in which the threshold value T1 is set as a reference of the absolute value of the strain amount has been described. However, the threshold value T1 is not limited to a value as the reference of the absolute value of the strain amount, and, for example, a threshold value for a change rate of the strain amount may be provided.

[0128] The output unit 714 outputs a determination result from the determination unit 713. For example, the display device 760 can be considered as an output destination of the determination result. However, the output destination may also be a terminal used by a worker performing remote control, a monitoring center monitoring the injection molding machine, or the like.

[0129] Next, a flow of a process of determining whether or not wear has occurred via the control device 700 according to the present embodiment will be described. Fig. Fig. 9 is a flowchart showing the flow of the process of determining whether or not wear has occurred via the control device 700 according to the present embodiment. Fig. In the flowchart shown in Figure 9, it is assumed that processes up to the mold closing / clamping process have been completed.

[0130] First, after the mold closing / clamping process is completed, the control unit 711 instructs the mold closing / clamping motor 160 to start the pressure release process (S901). Accordingly, during the pressure release process, the mold closing / clamping motor 160 starts controlling the crosshead 151 to move in the negative direction of the X-axis.

[0131] Next, the detection unit 712 detects the amount of strain from the signal output from the strain gauge 156 (S902).

[0132] The determination unit 713 determines whether the absolute value of the detected strain amount is greater than the threshold value T1 (S903). If it is determined that the absolute value of the detected strain amount is greater than the threshold value T1 (Yes at S903), the output unit 714 outputs to the display device 760 or the like that wear has occurred (S904), and the process is terminated.

[0133] On the other hand, if the determination unit 713 determines that the absolute value of the detected strain amount is equal to or less than the threshold value T1 (No at S903), the determination unit 713 determines whether the pressure relief process is completed (S905). If it is determined that the pressure relief process is not completed (No at S905), the process from S902 is performed again.

[0134] On the other hand, in a case where the determination unit 713 determines that the pressure relief process is completed (Yes at S905), the process is terminated.

[0135] In the present embodiment, by performing the above-described process, it is possible to determine whether or not the wear has occurred based on the amount of strain in the pressure release process. (Modification example of the first embodiment)

[0136] Moreover, in the above-described embodiment, the case where a monitoring device of the injection molding machine 10 is the control device 700 was described. However, in the above-described embodiment, the monitoring device of the injection molding machine 10 is not limited to the control device 700, and it may be any device capable of monitoring the injection molding machine 10. As a modification example, the monitoring device of 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, via a public network, information indicating that the pressure relief process has started and information indicating the amount of strain detected by the strain gauge 156. Then, the monitoring center determines whether or not wear has occurred based on the received information.

[0137] Furthermore, a portable diagnostic device owned by a worker periodically diagnosing the injection molding machine 10 may be used. When performing the diagnosis, the worker attaches the strain gauge 156 to any 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 has occurred based on whether the amount of strain indicated by the signal received from the strain gauge 156 is greater than the threshold value T1. (Second embodiment)

[0138] In the first embodiment, an example in which the strain gauge 156 is used to measure the amount of strain as the amount of change generated at the second link 153 (an example of the linking element) was described. However, in the above-described embodiment, the amount of change generated at the second link 153 (an example of the linking element) is not limited to the amount of strain. Therefore, in a second embodiment, a case in which acceleration is measured as the amount of change generated at the second link 153 will be described. In the present embodiment, the same configurations as those in the first embodiment are assigned the same reference numerals, and description thereof will be omitted.

[0139] In the present embodiment, an acceleration sensor is provided on the second link 153 (an example of the linking element) instead of the strain gauge 156. In the present embodiment, the acceleration sensor is provided in the area 602 of the Fig. 7 is provided. Although the acceleration sensor is provided in the region 602 in the present embodiment, the acceleration sensor may also be provided in another region.

[0140] The detection unit 712 detects an acceleration (an example of the amount of change) generated at the second link 153 based on a signal (measured value) in the pressure release process from the acceleration sensor provided at the second link 153 (an example of the linking element). In the present embodiment, whether or not wear has occurred is determined according to the acceleration detected in the pressure release process. As described above, in a case where the bushings 43B and 42B are worn, the friction coefficient of the sliding surface increases. Therefore, in a case where the force 1502 is generated in the pressure release process, vibration (acceleration) is generated in the region 602 due to the friction occurred within the bushings 43B and 42B.

[0141] The determination unit 713 determines whether or not an absolute value of the acceleration detected by the detection unit 712 exceeds a predetermined threshold T2.

[0142] Fig. Fig. 10 is a diagram illustrating a change in acceleration detected by the detection unit 712 in the pressure release process of the present embodiment. Fig. In the example shown in Figure 10, a horizontal axis represents the lapse of time, and a time "0" represents the time at which pressure release begins. A vertical axis represents the acceleration and the mold closing / clamping force.

[0143] As in Fig. As shown in Figure 10, after pressure release has begun, a mold closing / clamping force 1001 decreases over time and approaches a mold closing / clamping force of “0”.

[0144] In the Fig. The example shown in Figure 10 shows a change 1002 in acceleration in a case where wear has occurred. Fig. In the example shown in Figure 10, no acceleration (vibration) is generated at the time of starting pressure release. In a case where wear has occurred in the bushings 42B and 43B of the second link 153, acceleration (vibration) is generated when the second link 153 moves around the second link mechanism 42 to form an arc. In the present embodiment, the threshold value T2 (absolute value) is set as a criterion for determining whether or not wear has occurred.

[0145] The determination unit 713 determines an abnormality when the absolute value of the acceleration (vibration) is equal to or greater than the predetermined threshold T2. Therefore, since the absolute value of the acceleration becomes greater than the threshold T2 at time t2, the determination unit 713 determines that at least one of the bushings 42B and 43B of the second link 153 is worn. The output unit 714 then outputs the determination result from the determination unit 713.

[0146] Next, a flow of a process of determining whether or not wear has occurred via the control device 700 according to the present embodiment will be described. Fig. 11 is a flowchart showing the flow of the process of determining whether wear has occurred or not via the control device 700 according to the present embodiment. Fig.In the flowchart shown in Figure 11, it is assumed that processes up to the mold closing / clamping process have been completed.

[0147] First, after the mold closing / clamping process is completed, the control unit 711 instructs the mold closing / clamping motor 160 to start the pressure release process (S1101).

[0148] Next, the detection unit 712 detects the acceleration from the signal output from the acceleration sensor (S1102).

[0149] The determination unit 713 determines whether the absolute value of the detected acceleration is greater than the threshold T2 (S1103). If it is determined that the absolute value of the detected acceleration is greater than the threshold T2 (Yes at S1103), the output unit 714 outputs to the display device 760 or the like that wear has occurred (S1104), and the process is terminated.

[0150] On the other hand, if the determination unit 713 determines that the absolute value of the detected acceleration is equal to or less than the threshold T2 (No at S1103), the determination unit 713 determines whether the depressurization process is completed (S1105). If it is determined that the depressurization process is not completed (No at S1105), the process from S1102 is performed again.

[0151] On the other hand, in a case where the determination unit 713 determines that the pressure relief process is completed (Yes at S1105), the process is terminated.

[0152] In the present embodiment, by performing the above-described process, it is possible to determine whether or not the wear has occurred based on the acceleration in the pressure release process. (Modification example of second embodiment)

[0153] Similar to the modification example of the first embodiment, in the second embodiment, the monitoring device of the injection molding machine 10 may be any device capable of monitoring the injection molding machine 10, and may be, for example, a monitoring center connected to the injection molding machine 10 via a network or a portable diagnostic device owned by a worker diagnosing the injection molding machine 10.

[0154] Moreover, although an example of determining whether or not wear has occurred in the second link 153 has been described in the above-described embodiments and modification examples, the determination is not limited to the second link 153 and may be a plurality of link members constituting the toggle mechanism 150 and a link member to which a mold closing / clamping force is transmitted from the mold closing / clamping motor 160.

[0155] In the embodiments and modification examples described above, when the pressure relief process is performed, whether or not wear has occurred is determined based on the amount of change in strain, acceleration, or the like generated in the second link 153 (an example of the linking element). In a method of the present embodiment, unlike the prior art, it is not necessary to make a comparison with a state before wear, so that wear can be easily detected. Furthermore, when the measurement is performed, whether or not wear has occurred can be diagnosed by providing the strain gauge 156 or the acceleration sensor on the positive direction side of the Z-axis of the second link 153 in the toggle mechanism 150, so that it is possible to reduce a load during diagnosis.

[0156] Although the embodiments of the monitoring device of the injection molding machine according to the present invention have been described above, the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, omissions, and combinations are possible within the scope of the claims. Naturally, all of these also fall within the technical scope of the present invention.

[0157] This application claims priority based on Japanese Patent Application No. 2021-062430 filed on March 31, 2021, the entire contents of which are incorporated herein by reference. List of reference symbols 10 injection molding machine 110 stationary plate 120 movable plate 150 Knee lever mechanism 160 mold closing / clamping motor 800 molding units 152 first link 153 second link (example of linking element) 154 third link 42A, 43A connection hole 42B, 43B socket 700 control device 711 control unit 712 registration unit 713 Determination unit 714 Output unit

Claims

[1] Monitoring device (700) of an injection molding machine (10), comprising: a detection unit (712) which detects an amount of change generated at the linking element (153) on the basis of a measured value in a pressure relief process from a detection unit (156) provided at a linking element (153) of a toggle lever mechanism (150); and a determination unit (713) that, in a case after the pressure release has started, an absolute value of the amount of strain detected by the detection unit (712) increases and then gradually decreases, determines whether or not the absolute value exceeds a predetermined threshold value as the absolute value increases. [2] The monitoring device (700) of an injection molding machine (10) according to claim 1, wherein the amount of change generated at the linking element (153) detected by the detection unit (712) is an amount of strain generated at the linking element (153). [3] The monitoring device (700) of an injection molding machine (10) according to claim 1, wherein the amount of change generated at the linking element (153) detected by the detection unit (712) is an acceleration generated at the linking element (153). [4] Monitoring device (700) of an injection molding machine (10), comprising: a detection unit (712) which detects an amount of change generated at the linking element (153) on the basis of a measured value in a pressure relief process from a detection unit (156) provided at a linking element (153) of a toggle lever mechanism (150); and a determination unit (713) that determines whether or not the amount of change detected by the detection unit (712) or a rate of change of the amount of change exceeds a predetermined threshold, wherein the determination unit (713) determines whether wear occurs in the linking element (153) or a connecting mechanism (42, 43) when the predetermined threshold is exceeded by the amount of change or by the rate of change of the amount of change.

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