Control device for injection molding machine, and injection molding machine

Abstract

This allows for effective utilization of the motor's performance. [Solution] A control device for an injection molding machine according to one embodiment includes a control unit that obtains the current value flowing to a motor provided in the injection molding machine from a detection unit, calculates an integrated value by accumulating the current value detected by the motor for a predetermined time while the injection molding machine is continuously molding a molded product, and stops the molding by the injection molding machine based on the integrated value and a predetermined value, and the control unit further changes the predetermined value while the injection molding machine is continuously molding a molded product.

Description

Technical Field

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

Background Art

[0002] In a conventional injection molding machine, when molding a molded product, abnormal monitoring based on the detection result of a sensor is performed. For example, Patent Document 1 describes monitoring the temperature of a nozzle and stopping the energization of a band heater when the temperature of the nozzle reaches the allowable range temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In addition, the monitoring target for detecting abnormalities is not limited to the temperature of the nozzle or the like, and the current value for driving the motor is also a monitoring target. However, when determining whether or not information regarding the current value exceeds a predetermined value in order to monitor an abnormality, the current flowing through the motor may be restricted, and the performance of the motor may not be able to be exerted.

[0005] One aspect of the present invention provides a technique for monitoring the situation regarding a motor and effectively utilizing the performance of the motor according to the monitored situation.

Means for Solving the Problems

[0006] A control device for an injection molding machine according to one aspect of the present invention includes a control unit that obtains the current value flowing to a motor provided in the injection molding machine from a detection unit, calculates an integrated value by accumulating the current value detected by the motor for a predetermined time while the injection molding machine is continuously molding a molded product, and stops the molding by the injection molding machine based on the integrated value and a predetermined value, and the control unit further changes the predetermined value while the injection molding machine is continuously molding a molded product. [Effects of the Invention]

[0007] According to one aspect of the present invention, the performance of the motor can be effectively utilized. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the state of an injection molding machine upon completion of mold opening according to one embodiment. [Figure 2] This figure shows the state of an injection molding machine during mold clamping according to one embodiment. [Figure 3] This figure illustrates the motor control configuration in an injection molding machine according to the first embodiment. [Figure 4] This figure shows the correspondence for deriving the first protection current threshold stored in the first protection current threshold storage unit according to the first embodiment. [Figure 5] This flowchart illustrates the procedure for abnormality monitoring based on the integrated current value of the current input to the motor in the control device according to the first embodiment. [Figure 6] This figure shows a motor cooling system according to the second embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Furthermore, the embodiments described below are illustrative and not limiting to the invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the invention. In addition, identical or corresponding components in each drawing 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 describing the mold 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.

[0013] The mold clamping device 100 performs mold closing, pressure increasing, mold clamping, pressure decreasing, and mold opening of the mold apparatus 800. The mold apparatus 800 includes a fixed mold 810 and a movable mold 820. The mold clamping device 100 is, for example, a horizontal type, and the mold opening and closing direction is horizontal. The mold 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 relative to the fixed platen 110 in the mold opening and closing direction.

[0014] The fixed platen 110 is fixed to the clamping device frame 910. The fixed mold 810 is attached to the surface of the fixed platen 110 facing the movable platen 120.

[0015] The movable platen 120 is positioned to move freely in the mold opening and closing direction relative to the mold clamping device frame 910. Guides 101 are laid on the mold clamping device frame 910 to guide the movable platen 120. A movable mold 820 is attached to the surface of the movable platen 120 facing the fixed platen 110.

[0016] The moving mechanism 102 performs mold closing, pressure increasing, mold clamping, depressurization, and mold opening of the mold device 800 by moving the movable platen 120 forward and backward relative to the fixed platen 110. The moving mechanism 102 includes a toggle support 130 positioned at a distance 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 and closing direction relative to the toggle support 130, a mold clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the mold clamping motor 160 into linear motion, and a mold thickness adjustment mechanism 180 that adjusts the distance between the fixed platen 110 and the toggle support 130.

[0017] The toggle support 130 is disposed at an interval from the fixed platen 110 and is placed movably in the mold opening / closing direction on the mold clamping device frame 910. Incidentally, the toggle support 130 may be movably arranged along a guide laid on the mold clamping device frame 910. The guide of the toggle support 130 may be common with the guide 101 of the movable platen 120.

[0018] In this embodiment, the fixed platen 110 is fixed to the mold clamping device frame 910, and the toggle support 130 is movably arranged in the mold opening / closing direction with respect to the mold clamping device frame 910. However, the toggle support 130 may be fixed to the mold clamping device frame 910, and the fixed platen 110 may be movably arranged in the mold opening / closing direction with respect to the mold clamping device frame 910.

[0019] The tie bars 140 connect the fixed platen 110 and the toggle support 130 with an interval L in the mold opening / closing direction. A plurality of (for example, four) tie bars 140 may be used. The plurality of tie bars 140 are arranged in parallel in the mold opening / closing direction and extend according to the clamping force. At least one of the tie bars 140 may be provided with a tie bar strain detector 141 for detecting the strain of the tie bar 140. The tie bar strain detector 141 sends a signal indicating the detection result to the control device 700. The detection result of the tie bar strain detector 141 is used for detecting the clamping force and the like.

[0020] In this embodiment, the tie bar strain detector 141 is used as the clamping force detector for detecting the clamping force, but the present invention is not limited thereto. The clamping force detector is not limited to the strain gauge type, and may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, etc., and its mounting position is not limited to the tie bar 140.

[0021] The toggle mechanism 150 is positioned between the movable platen 120 and the toggle support 130, and moves the movable platen 120 in the mold opening and closing direction relative to the toggle support 130. 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 of the link groups has a first link 152 and a second link 153 that are bendable and extendable connected by a pin or the like. The first link 152 is pivotably attached to the movable platen 120 by a pin or the like. The second link 153 is pivotably attached to the toggle support 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 moves forward and backward relative to the toggle support 130, the first link 152 and the second link 153 bend and extend, and the movable platen 120 moves forward and backward relative to the toggle support 130.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] The setting conditions for the mold closing process, the pressurization 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 pressurization 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.

[0034] 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.

[0035] 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.

[0036] 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°.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] (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.

[0047] 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).

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] (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.

[0053] 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 in the mold device 800 with the molding material metered in the cylinder 310. 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Furthermore, the pressure detector used to detect the pressure of the molding material is not limited to the load detector 360, but a general-purpose one can be used. For example, a nozzle pressure sensor or an in-mold pressure sensor may be used. The nozzle pressure sensor is installed on the nozzle 320.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] (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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] (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, an output interface 704, and a communication interface 705. 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.

[0089] The control device 700 repeatedly produces 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."

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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 touch panel 770 accepts operations in the displayed screen area. The screen area 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 configure the injection molding machine 10 (including inputting setting values), etc. Furthermore, the user can operate the injection molding machine 10 corresponding to the operation unit by operating the operation unit provided on the screen. The operation of the injection molding machine 10 may include, for example, the operation (including stopping) of the clamping device 100, ejector device 200, injection device 300, moving device 400, etc. Alternatively, the operation of the injection molding machine 10 may include switching the screen displayed on the touch panel 770, which serves as the display device 760.

[0096] 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).

[0097] (First Embodiment) Figure 3 is a diagram illustrating the motor control configuration in the injection molding machine 10 according to this embodiment. In the example shown in Figure 3, a control device 700, a motor 1301, a motor encoder 1302, an IPM 1303, a current detector 1304, and a temperature sensor 1305 are shown.

[0098] The motor 1301 shown in Figure 3 can be any motor included in the injection molding machine 10, for example, a motor that uses an air-cooling system. Motor 1301 may be, for example, an injection motor 350, a metering motor 340, a clamping motor 160, an ejector motor, a mold thickness adjustment motor 183, or a motor 420. Other examples of motor 1301 include a motor for a supply device that supplies molding material to the cylinder 310, or a motor for a pump in the injection molding machine 10, such as a pump used for opening and closing the mold device 800.

[0099] The motor encoder 1302 detects the rotation of the motor 1301 and transmits a signal indicating the detection result to the control device 700.

[0100] The Intelligent Power Module (IPM) 1303 is a module for driving the motor 1301 according to current commands from the control device 700, which include command values ​​for each phase. For example, the IPM 1303 receives current commands from the control device 700, which include command values ​​(Vu, Vv, Vw) for each phase of the motor 1301, and outputs currents (u, v, w) corresponding to the command values ​​for each phase to each phase of the motor 1301. In addition, both the IPM 1303 and the control device 700 are connected to a power supply (not shown) via PN lines.

[0101] The current detector 1304 detects the current (value) output from the IPM 1303 to the motor 1301 and transmits a signal indicating the detection result to the control device 700.

[0102] The temperature sensor 1305 detects the ambient temperature near the injection molding machine 10 and transmits a signal indicating the detection result to the control device 700. In this embodiment, the temperature sensor 1305 is shown as an example of detecting the ambient temperature near the injection molding machine 10, but it is sufficient to detect the temperature outside the motor 1301, or the temperature around the motor 1301.

[0103] The control device 700 according to this embodiment outputs a current command value for driving the motor 1301 based on the signals input from the above configuration and the molding conditions.

[0104] The control device 700 according to this embodiment includes a CPU 701 and a storage medium 702, as well as a first board 706 and a second board 707 for receiving signals from other components.

[0105] In this embodiment, the control device 700 calculates an integrated value by accumulating the current value detected by the motor 1301 for a predetermined time while the injection molding machine 10 is continuously molding molded products. The control device 700 then determines whether the calculated integrated value exceeds the protection current threshold (first protection current threshold or second protection current threshold), and if it determines that it has exceeded the threshold, it stops the molding by the injection molding machine 10.

[0106] Conventionally, when monitoring for abnormalities by determining whether the cumulative value obtained by accumulating the current value detected by the motor over a predetermined period of time exceeds a predetermined threshold, the protection current threshold was set as a fixed value. Furthermore, the protection current threshold was often set with a certain margin of safety. As a result, when outputting a current value in a way that does not exceed the protection current threshold, the motor's driving force was reduced, potentially leading to a decrease in work efficiency.

[0107] A margin in the protection current threshold arises, for example, when the protection current threshold is set assuming a temperature higher than that of the environment in which the injection molding machine is used. Specifically, if the ambient temperature around the motor is lower than the assumed temperature, even if the cumulative value of the current flowing through the motor reaches the protection current threshold, there is a margin before any malfunction occurs in the motor or other components.

[0108] Furthermore, a margin in the protection current threshold arises, for example, when the protection current threshold is set considering the case when the motor is operating at its maximum rotational speed. The amount of heat generated by the motor changes depending on the rotational speed. Therefore, when the motor is rotating at a rotational speed lower than its maximum rotational speed, even if the cumulative value of the current flowing through the motor reaches the protection current threshold, there is a margin before any abnormality occurs in the motor or other components.

[0109] Therefore, the control device 700 according to this embodiment changes a protective current threshold, which serves as a criterion for determining the cumulative value obtained by accumulating the current value detected by the motor over a predetermined period of time while the injection molding machine 10 is continuously molding molded products.

[0110] The storage medium 702 stores various installed programs, as well as files and data necessary for various processes. The storage medium 702 includes, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or flash memory.

[0111] The storage medium 702 stores the first protection current threshold storage unit 721 and the second protection current threshold storage unit 722. The first protection current threshold storage unit 721 and the second protection current threshold storage unit 722 will be described later.

[0112] The CPU 701 executes the program stored in the storage medium 702. As a result, the CPU 701 implements the following functional units: a motor control command generation unit 1701, an output control unit 1702, a current command generation unit 1703, a current detection value input unit 1704, a temperature input unit 1705, a rotation speed input unit 1706, a first update unit 1707, a second update unit 1708, a first current integration unit 1709, a second current integration unit 1710, a first comparison unit 1711, a second comparison unit 1712, and an abnormality control unit 1713.

[0113] The motor control command generation unit 1701 generates a control command to control the motor 1301 based on the molding conditions and the current value flowing through the motor 1301 input from the current detection value input unit 1704, and outputs the control command to the current command generation unit 1703 via the output control unit 1702.

[0114] The motor control command generation unit 1701 generates control commands for performing control based on the molding conditions. The method for generating the control commands may be the same as conventional methods, and therefore the explanation is omitted.

[0115] Furthermore, the motor control command generation unit 1701 performs feedback control to adjust the control command by considering the current value flowing through the motor 1301 input from the current detection value input unit 1704. The feedback control can be performed using conventional control methods such as PI control, so its explanation will be omitted.

[0116] The output control unit 1702 switches whether or not to output the control command input from the motor control command generation unit 1701 to the current command generation unit 1703, according to the control from the abnormality control unit 1713, which will be described later.

[0117] The current command generation unit 1703 generates a current command including the command values ​​(Vu, Vv, Vw) for each phase of the motor 1301 according to the input control command, and outputs it to the IPM 1303.

[0118] The current detection value input unit 1704 receives a signal from the current detector 1304 indicating the detection result of the current value output to the motor 1301, and outputs information indicating the current value flowing through the motor 1301 to the motor control command generation unit 1701 and the first current integration unit 1709.

[0119] The temperature input unit 1705 receives a signal from the temperature sensor 1305 indicating the detection result of the ambient air temperature and outputs information indicating the ambient air temperature to the first update unit 1707 and the second update unit 1708.

[0120] The rotation speed input unit 1706 receives a signal from the motor encoder 1302 indicating the detection result of the rotation of the motor 1301, and outputs information indicating the rotation speed of the motor 1301 to the first update unit 1707 and the second update unit 1708.

[0121] The first current integration unit 1709 calculates a first current integration value by integrating the current value for a first time period according to the information input from the current detection value input unit 1704. The first time period can be any time determined according to the embodiment, for example, 1 second.

[0122] The second current integration unit 1710 further integrates the first current integration value calculated by the first current integration unit 1709 to calculate a second current integration value obtained by integrating the current values ​​for a second time. The second time is a longer period than the first time, for example, 1 minute.

[0123] The control device 700 according to this embodiment monitors for abnormalities in the current flowing through the motor 1301 using a first current integrated value over a short period (e.g., 1 second) and a second current integrated value over a long period (e.g., 1 minute).

[0124] The control device 700 can detect instantaneous overcurrent anomalies by using a first current integral value taken over a short period (e.g., 1 second) for anomaly monitoring. Furthermore, the control device 700 can detect anomalies in the sum of current values ​​in situations where current values ​​are repeatedly excited at predetermined cycle intervals (but do not reach a level that can be detected as an overcurrent) by using a second current integral value taken over a long period (e.g., 1 minute) for anomaly monitoring.

[0125] The first update unit 1707 updates the first protection current threshold used by the first comparison unit 1711 for comparison with the first integrated current value. In this embodiment, the first update unit 1707 derives the first protection current threshold corresponding to the rotational speed of the motor 1301 and the ambient temperature from the first protection current threshold storage unit 721.

[0126] The first protection current threshold memory unit 721 stores the correspondence between the ambient temperature, the rotational speed of the motor 1301, and the first protection current threshold, and is used by the first update unit 1707 to update the first protection current threshold.

[0127] Figure 4 is a diagram showing the correspondence for deriving the first protection current threshold stored in the first protection current threshold storage unit 721 according to this embodiment. In the example shown in Figure 4, the horizontal axis is the rotational speed of the motor 1301, and the vertical axis is the first protection current threshold.

[0128] Line 1401 shows the case where the ambient temperature is a first temperature, and line 1402 shows the case where the ambient temperature is a second temperature. The first temperature is higher than the second temperature. The first temperature may be, for example, 50 degrees, and the second temperature may be, for example, 25 degrees.

[0129] Figure 4 shows a case where the correspondence between a first temperature and a second temperature is set in the first protection current threshold storage unit 721. However, in this embodiment, the first protection current threshold storage unit 721 does not limit the temperatures associated with the first protection current threshold to two; rather, it is sufficient that the correspondence between temperature and the protection current threshold is set so that the first protection current threshold corresponding to the temperature detected by the temperature sensor 1305 can be derived.

[0130] As shown in Figure 4, the first update unit 1707 identifies a first protection current threshold corresponding to the rotational speed of the motor 1301 and the temperature detected by the temperature sensor 1305, and updates (changes) the identified first protection current threshold for use in comparison with the first integrated current value.

[0131] For example, the value shown on the vertical axis of point 1411 is the conventionally set first protection current threshold. In other words, the conventionally set first protection current threshold is used when the rotational speed of motor 1301 is R1 and the temperature is a first.

[0132] Furthermore, if the rotational speed of the motor 1301 is R1, but the ambient temperature drops from the first temperature to the second temperature, the first update unit 1707 changes the first protection current threshold to the value shown on the vertical axis of point 1421.

[0133] Furthermore, if the ambient temperature is the first temperature, but the rotational speed of the motor 1301 decreases from R1 to R2, the first update unit 1707 changes the first protection current threshold to the value shown on the vertical axis of point 1412.

[0134] Furthermore, if the rotational speed of the motor 1301 decreases from R1 to R2, and the ambient temperature decreases from the first temperature to the second temperature, the first update unit 1707 changes the first protection current threshold to the value shown on the vertical axis of point 1422.

[0135] As described above, the first update unit 1707 according to this embodiment changes the first protection current threshold according to the rotational speed of the motor 1301 and the ambient temperature.

[0136] In other words, if the motor 1301 is air-cooled, the first update unit 1707 according to this embodiment changes the first protection current threshold based on the external temperature of the motor 1301 detected by the temperature sensor (an example of a second detection unit) 1305.

[0137] Furthermore, the first update unit 1707 according to this embodiment changes the first protection current threshold based on the rotational speed of the motor 1301 detected by the motor encoder (an example of a third detection unit) 1302.

[0138] The second update unit 1708 updates the second protection current threshold, which is used in the second comparison unit 1712 for comparison with the second integrated current value. In this embodiment, the second update unit 1708 derives the second protection current threshold corresponding to the rotational speed of the motor 1301 and the ambient temperature from the second protection current threshold storage unit 722.

[0139] The second protection current threshold storage unit 722 stores the correspondence between the ambient temperature, the rotational speed of the motor 1301, and the second protection current threshold, and is used by the second update unit 1708 to update the second protection current threshold. The correspondence stored in the second protection current threshold storage unit 722 is the same as in Figure 4, except that the vertical axis is changed from the first protection current threshold to the second protection current threshold, so its explanation is omitted.

[0140] Incidentally, conventionally, protection current thresholds were set to correspond to rotational speeds and temperatures higher than those actually used in injection molding machines. Therefore, the first update unit 1707 and the second update unit 1708 in this embodiment can set a first protection current threshold and a second protection current threshold that are higher than the values ​​used conventionally, based on the rotational speed of the motor 1301 and the ambient temperature.

[0141] The first comparison unit 1711 determines whether the first current integration value calculated by the first current integration unit 1709 is greater than the first protection current threshold value updated by the first update unit 1707. The first comparison unit 1711 then outputs the determination result to the abnormality control unit 1713.

[0142] The second comparison unit 1712 determines whether the second current integration value calculated by the second current integration unit 1710 is greater than the second protection current threshold value, which is updated by the second update unit 1708. The second comparison unit 1712 then outputs the determination result to the abnormality control unit 1713.

[0143] The abnormality control unit 1713 controls the output control unit 1702 based on the determination results input from the first comparison unit 1711 and the second comparison unit 1712.

[0144] For example, if the error control unit 1713 determines, based on the determination result by the first comparison unit 1711, that the first integrated current value exceeds the first protection current threshold, it instructs the output control unit 1702 to stop outputting control commands from the motor control command generation unit 1701 to the current command generation unit 1703. In this case, the error control unit 1713 may output a control command to the current command generation unit 1703 to stop the motor 1301.

[0145] As another example, if the error control unit 1713 determines, based on the judgment result of the second comparison unit 1712, that the second integrated current value exceeds the second protection current threshold, it instructs the output control unit 1702 to stop outputting control commands from the motor control command generation unit 1701 to the current command generation unit 1703. In this case, the error control unit 1713 may output a control command to the current command generation unit 1703 to stop the motor 1301.

[0146] In this embodiment, the abnormality control unit 1713 may perform control to immediately stop the motor according to the determination result, but if it stops in the middle of the molding cycle, there are situations where purging or the like is necessary. Therefore, the abnormality control unit 1713 may operate the motor 1301 with the current value suppressed until the completion of the molding cycle, and then perform control to stop it after the completion of the molding cycle. Furthermore, in this embodiment, an example is shown in which an abnormality is detected according to whether the integrated current value (first integrated current value or second integrated current value) exceeds the protection current threshold (first protection current threshold or second protection current threshold), but the determination is not limited to whether or not the protection current threshold has been exceeded. The determination of whether or not an abnormality is present can be based on a predetermined value that serves as a criterion for determination, such as the protection current threshold (e.g., first protection current threshold or second protection current threshold), and the integrated current value (e.g., first integrated current value or second integrated current value).

[0147] In this embodiment, the motor 1301, which changes the protection current threshold considering the combination of external temperature and rotational speed, can be applied to, for example, the injection motor 350, metering motor 340, and ejector motor of the injection molding machine 10, but it may also be applied to other motors.

[0148] Furthermore, the control device 700 according to this embodiment is not limited to changing the protection current threshold (first protection current threshold or second protection current threshold) based on the external temperature of the motor 1301 and the rotational speed of the motor 1301. Depending on the type of motor of the injection molding machine 10, the control device 700 may also change the protection current threshold (first protection current threshold or second protection current threshold) based on the external temperature of the motor 1301. Examples of motors to which this embodiment can be applied include the clamping motor 160, the mold thickness adjustment motor 183, or the motor 420.

[0149] Furthermore, the control device 700 may also change the protection current threshold (first protection current threshold or second protection current threshold) based on the rotational speed of the motor 1301 detected by the motor encoder (an example of a third detection unit) 1302.

[0150] Figure 5 is a flowchart illustrating the procedure for abnormality monitoring based on the integrated current value of the current input to the motor 1301 in the control device 700 according to this embodiment.

[0151] First, the motor control command generation unit 1701 generates a control command based on the molding conditions (S1501).

[0152] Next, the current command generation unit 1703 generates a current command according to the control command and outputs it to the IPM 1303 (S1502). The IPM 1303 then controls the rotation of the motor 1301 according to the input current command.

[0153] The current detection value input unit 1704 then processes a signal from the current detector 1304 indicating the detection result of the current value (S1503). The current detection value input unit 1704 then outputs information indicating the current value flowing through the motor 1301 to the motor control command generation unit 1701 and the first current integration unit 1709.

[0154] Then, the first current integration unit 1709 calculates a first current integration value by integrating the current value for the first time period according to the information input from the current detection value input unit 1704, and the second current integration unit 1710 further integrates the first current integration value to calculate a second current integration value by integrating the current value for the second time period (S1504).

[0155] Then, the temperature input unit 1705 processes the signal output from the temperature sensor 1305, which indicates the detection result of the ambient temperature, and the rotation speed input unit 1706 processes the signal output from the motor encoder 1302, which indicates the detection result of the rotation of the motor 1301 (S1505).

[0156] The first update unit 1707 refers to the first protection current threshold storage unit 721 and updates it to the first protection current threshold corresponding to the rotational speed of the motor 1301 and the ambient temperature, and the second update unit 1708 refers to the second protection current threshold storage unit 722 and updates it to the second protection current threshold corresponding to the rotational speed of the motor 1301 and the ambient temperature (S1506).

[0157] The first comparison unit 1711 determines whether the first integrated current value is greater than the first protection current threshold, and the second comparison unit 1712 determines whether the second integrated current value is greater than the second protection current threshold (S1507).

[0158] If the first comparison unit 1711 determines that the first integrated current value is less than or equal to the first protection current threshold, and the second comparison unit 1712 determines that the second integrated current value is less than or equal to the second protection current threshold (S1507: NO), the motor control command generation unit 1701 generates a control command based on the molding conditions and the current value input from the current detection value input unit 1704 (S1508). In other words, if the first integrated current value and the second integrated current value are determined to be normal, the motor control command generation unit 1701 generates a control command by feedback control based on the input current value along with the molding conditions. After that, processing is carried out again from S1502.

[0159] On the other hand, if the first comparison unit 1711 determines that the first current integrated value is greater than the first protection current threshold, or if the second comparison unit 1712 determines that the second current integrated value is greater than the second protection current threshold (S1507: YES), the abnormality control unit 1713 instructs the output control unit 1702 to stop the output of control commands from the motor control command generation unit 1701 and to stop the motor 1301 (S1509).

[0160] The control device 700 according to this embodiment continuously performs the process shown in Figure 5 during one shot in which the injection molding machine 10 forms a molded product. In other words, the control device 700 according to this embodiment changes the first protection current threshold and the second protection current threshold during one shot in which the injection molding machine 10 forms a molded product.

[0161] The control device 700 according to this embodiment continues to perform the processing shown in Figure 5 not only during a single shot, but also when multiple shots are performed consecutively. In other words, the control device 700 changes the first protection current threshold and the second protection current threshold between the first shot that forms the first molded product and the second shot that forms the second molded product.

[0162] The storage medium 702 according to this embodiment stores the first protection current threshold storage unit 721 and the second protection current threshold storage unit 722 as information that determines the first protection current threshold and the second protection current threshold based on the status of the injection molding machine 10.

[0163] Therefore, when the status of the injection molding machine 10 is acquired, the first update unit 1707 and the second update unit 1708 set the first protection current threshold and the second protection current threshold based on the acquired status and the first protection current threshold storage unit 721 and the second protection current threshold storage unit 722.

[0164] This embodiment describes an example of acquiring the rotational speed of the motor 1301 and the ambient temperature around the injection molding machine 10 as an example of the conditions of the injection molding machine 10. However, the conditions of the injection molding machine 10 are not limited to the rotational speed of the motor 1301 and the ambient temperature around the injection molding machine 10, but any conditions related to or affecting the operation of the motor 1301 are acceptable.

[0165] The control device 700 according to this embodiment does not limit the control for monitoring abnormalities in the injection molding machine 10 to determining whether the integrated value of the current exceeds the protection current threshold, but may also combine other abnormality monitoring methods. Other abnormality monitoring methods include, for example, monitoring the temperature of the motor 1301. However, since monitoring the temperature of the motor 1301 only monitors a portion of the temperature, it is difficult to detect localized heat generation in phase-locked states, etc. The control device 700 according to this embodiment can perform dual monitoring of abnormalities in the injection molding machine 10 by combining monitoring the temperature of the motor 1301 with determining whether the integrated value of the current exceeds the protection current threshold, thereby improving safety.

[0166] In this embodiment, the control device 700 is modified so that the first protection current threshold and the second protection current threshold increase as the rotational speed of the motor 1301 decreases. In other words, the control device 700 in this embodiment makes it possible to supply a larger current to the motor 1301 as the rotational speed of the motor 1301 decreases.

[0167] For example, conventionally, there have been cases where a low motor speed was sufficient, but high torque was required. In such cases, when the motor was outputting high torque, the integrated power value could exceed the protection current threshold, potentially causing the motor to stop and resulting in molding defects.

[0168] In contrast, the control device 700 according to this embodiment increases the first and second protection current thresholds as the rotational speed of the motor 1301 decreases, enabling the output of high torque and thus suppressing the stopping of the motor 1301. Therefore, it is possible to suppress the occurrence of molding defects and the waste of molding material due to molding defects.

[0169] In this embodiment, the first protection current threshold and the second protection current threshold, after being modified by the control device 700, are set to be lower than the rated current value of the power line or terminal block, etc. Therefore, this embodiment makes it possible to ensure safety.

[0170] (Second embodiment) In the embodiments described above, the case in which an air-cooled motor 1301 is applied was explained. However, the embodiments described above do not limit the motor to which the above-described control is applied to a motor using a water-cooled system, and may also be applied to a water-cooled motor. Therefore, in this embodiment, the case in which it is applied to an injection molding machine 10 having a water-cooled motor will be explained.

[0171] The water-cooled motor can be applied to any motor provided in the injection molding machine 10, but for example, it can be applied to the injection motor 350.

[0172] Figure 6 shows the cooling system of the motor 1301A according to this embodiment. The cooling system 1600 shown in Figure 6 includes a circulation passage 1611 that returns the coolant CL that has passed through a flow path provided in the motor case 1601 of the motor 1301A to the said flow path, and a heat exchanger 1620 provided in the middle of the circulation passage 1611. The heat exchanger 1620 cools the coolant CL by transferring the heat from the coolant CL to cold water CW such as industrial water. The coolant CL cooled by the heat exchanger 1620 is sent again to the flow path in the motor case 1601 and used to cool the motor 1301A.

[0173] In this embodiment, the motor 1301A is housed inside a motor case 1601, which is provided with a passage for the coolant CL to pass through. As a result, the motor 1301A is cooled by the coolant CL passing through the passage provided in the motor case 1601.

[0174] The circulation passage 1631 of the cooling system 1600 includes a cooling path 1631a that allows the coolant CL to flow through the heat exchanger 1620, a bypass path 1631b that prevents the coolant CL from passing through the heat exchanger 1620, and a directional switching valve 1632 located upstream of the heat exchanger 1620 and at the branching point between the cooling path 1631a and the bypass path 1631b.

[0175] The cooling system 1600 circulates coolant CL through a flow path that is cooled by the heat exchanger 1620 via the cooling path 1631a before being guided to the motor case 1601. If the temperature of the coolant CL becomes too low, the directional valve 1632 switches the path through which the coolant CL flows from the cooling path 1631a to the bypass path 1631b. The coolant CL passing through the bypass path 1631b is not cooled by the heat exchanger 1620, so its temperature rises. This prevents an excessive drop in the temperature of the coolant CL.

[0176] Furthermore, after the temperature of the coolant CL flowing through the bypass path 1631b has risen to a certain extent, the directional valve 1632 switches the path through which the coolant CL flows from the bypass path 1631b to the cooling path 1631a. As a result, the coolant CL is cooled by the heat exchanger 1620, and its temperature decreases again.

[0177] In the cooling system 1600, a reserve tank 1650 is provided in the middle of the circulation passage 1631, downstream of the heat exchanger 1620, and downstream of the confluence point MP of the cooling path 1631a and the bypass path 1631b. Furthermore, in the cooling system 1600, a coolant supply pump 1633 is provided downstream of the reserve tank 1650 to send coolant CL into the flow path of the motor case 1601.

[0178] Furthermore, the cooling system 1600 includes a temperature sensor 1661 for measuring the ambient temperature in the environment where the motor 1301A is installed, and a liquid temperature sensor 1662 for measuring the temperature of the coolant CL supplied to the flow path of the motor case 1601. The temperature sensor 1661 and the liquid temperature sensor 1662 are, for example, thermocouples. In this embodiment, the temperature sensor 1661 is provided around the motor 1301A, and the liquid temperature sensor 1662 is provided inside the reserve tank 1650. Note that this embodiment does not restrict the location of the temperature sensor 1661 and the liquid temperature sensor 1662. The liquid temperature sensor 1662 only needs to be capable of measuring the temperature of the coolant CL flowing into the flow path of the motor case 1601.

[0179] According to this cooling system 1600, the temperature of the coolant CL is monitored by the liquid temperature sensor 1662, and the directional control valve 1632 is activated in response to the change in temperature, thereby suppressing the occurrence of condensation in the motor 1301A.

[0180] Conventionally, when a motor is water-cooled, a threshold value was set for the cumulative current flowing through the motor over a predetermined period of time, taking into account that the refrigerant temperature is at a predetermined temperature, in order to detect a malfunction in the motor. In other words, if the refrigerant temperature changes, there may be a margin of error in the threshold value of the cumulative current.

[0181] Therefore, in the case where the motor 1301A is water-cooled, the control device 700 according to this embodiment changes the first protection current threshold and the second protection current threshold based on the temperature of the refrigerant detected by the liquid temperature sensor (an example of a first detection unit) 1662.

[0182] Specifically, the first protection current threshold storage unit 721 stores the correspondence between the refrigerant temperature, the rotational speed of the motor 1301A detected by the motor encoder 1302, and the first protection current threshold. Then, the second protection current threshold storage unit 722 stores the correspondence between the refrigerant temperature, the rotational speed of the motor 1301A detected by the motor encoder 1302, and the second protection current threshold.

[0183] Furthermore, the first update unit 1707 according to this embodiment changes the first protection current threshold according to the rotational speed of the motor 1301A and the temperature of the refrigerant.

[0184] Similarly, the second update unit 1708 according to this embodiment changes the second protection current threshold according to the rotational speed of the motor 1301A and the temperature of the refrigerant.

[0185] The control device 700 according to this embodiment changes the protection current threshold according to the temperature of the refrigerant. In other words, this embodiment makes it possible to supply a larger current to the motor 1301A as the temperature of the refrigerant decreases. Therefore, it becomes possible to utilize the performance of the motor 1301A more effectively, such as enabling the motor 1301A to output a higher torque.

[0186] In this embodiment, the case where a water-cooled motor is used has been described. However, this embodiment is not limited to the use of a water-cooled motor, and an oil-cooled motor may also be used in the injection molding machine 10. The control when an oil-cooled motor is used is the same as in this embodiment and will not be described further.

[0187] (Variation 1) In the embodiments described above, an example was given in which the protection current threshold is changed according to the ambient temperature or refrigerant temperature and the motor speed. However, the embodiments described above do not limit the parameters for changing the protection current threshold to one or more of the ambient temperature or refrigerant temperature and the motor speed; any parameter related to the operation of the motor is acceptable.

[0188] Modification 1 is applied to a metering motor 340 for rotating a screw provided in an injection molding machine 10. In this modification, the control device 700 changes the first protection current threshold and the second protection current threshold according to one or more of the following: the shot volume, which is the volume of molding material poured into the mold device 800, and the metering completion position by the screw 330. The shot volume can be calculated according to the metered value of the molding material and the metering position of the screw 330. The reason for changing the first protection current threshold and the second protection current threshold according to one or more of the shot volume and the metering completion position is that the shot volume and the metering completion position by the screw 330 are correlated with the rotation speed of the motor 1301.

[0189] In other words, the control device 700 according to this modified example changes the first protection current threshold and the second protection current threshold according to one or more of the following, which are correlated with the rotational speed of the motor 1301: the shot volume and the metering completion position by the screw 330. The control device 700 according to this modified example makes it possible to utilize the performance of the motor 1301 more effectively, such as enabling the motor 1301 to output a higher torque.

[0190] Alternatively, the control device 700 may change the first protection current threshold and the second protection current threshold according to the metering position of the screw 330, instead of using a shot volume control.

[0191] (Modification 2) The protection current threshold may be changed based on a parameter correlated with the rotational speed of the motor 1301, without being limited to the embodiments and modifications described above.

[0192] Modification 2 applies to a metering motor 340 used to rotate a screw 330 provided in an injection molding machine 10. For example, the rotational speed of the metering motor 340 is correlated with the viscosity of the molding material.

[0193] Therefore, the control device 700 according to this modified example changes the first protection current threshold and the second protection current threshold based on at least one of the following: the type of molding material and the temperature of the molding material. Alternatively, the temperature of the cylinder 310 may be used instead of the temperature of the molding material. In this case, the control device 700 changes the first protection current threshold and the second protection current threshold based on the temperature of the cylinder 310.

[0194] Another example is that the rotational speed of the metering motor 340 correlates with the characteristics of the screw 330.

[0195] Therefore, the control device 700 according to this modified example changes the first protection current threshold and the second protection current threshold based on at least one of the rotational speed of the screw 330 and the type of screw 330.

[0196] In this modified example, the storage medium 702 may store a correspondence between one or more of the following: the rotational speed of the screw 330, the type of molding material, the temperature of the molding material in the cylinder 310, the temperature of the cylinder 310 provided in the injection molding machine 10, and the type of screw 330, and the protection current threshold (first protection current threshold and second protection current threshold). In this case, the control device 700 according to this modified example changes the first protection current threshold and the second protection current threshold by referring to the correspondence.

[0197] The type of molding material and the type of screw 330 may be information input to the user via the operating device 750, or information received from a management device to which the injection molding machine 10 is communicatively connected. The rotational speed of the screw 330, the temperature of the molding material in the cylinder 310, and the temperature of the cylinder 310 provided in the injection molding machine 10 are, for example, the results of detection by a detection unit provided in the injection molding machine 10.

[0198] Furthermore, if information regarding the molding material, such as the viscosity of the molding material, is input via the operating device 750, the control device 700 may change the first protection current threshold and the second protection current threshold based on the viscosity of the molding material.

[0199] Furthermore, the control device 700 may change the first protection current threshold and the second protection current threshold depending on the type of mold device 800. In this case, the storage medium 702 stores the correspondence between the type of mold device 800 and the protection current thresholds (first protection current threshold and second protection current threshold). When a user inputs the type of mold device via the operating device 750, the control device 700 refers to the correspondence and changes the first protection current threshold and the second protection current threshold to those corresponding to the type of mold device 800.

[0200] <effect> In the embodiments and modifications described above, the cumulative value of power flowing into the motor over a predetermined time can be increased by changing the first and second protective current thresholds, thereby enabling effective utilization of the motor's performance. Therefore, in the injection molding machines according to the embodiments and modifications described above, the motor can be used under high load depending on the conditions and environment.

[0201] While conventional methods exist for monitoring motor temperature using temperature sensors, this only monitors a portion of the motor temperature. Therefore, by combining motor temperature monitoring with the abnormality monitoring described in the above-described embodiments and modifications, dual monitoring of abnormalities in the injection molding machine can be performed. Consequently, the above-described embodiments and modifications can improve safety.

[0202] In the embodiments and modifications described above, the first and second protection current thresholds are changed based on the external temperature of the motor or the temperature of the refrigerant used to cool the motor. Therefore, in the injection molding machine according to the embodiments and modifications described above, the motor can be used under high load depending on the external temperature or the temperature of the refrigerant used to cool the motor.

[0203] In conventional injection motors, during molding with long holding pressure times, the proportion of motor torque generated during a single cycle is high. This can cause the integrated current to exceed the protection current threshold, leading to abnormal shutdowns.

[0204] In contrast, the control device 700 according to the above-described embodiment and modified example changes the first protection current threshold and the second protection current threshold corresponding to the injection motor 350. This makes it possible to suppress the cumulative value of the current from exceeding one or more of the first protection current threshold and the second protection current threshold, even when the proportion of motor torque generated during one cycle is high.

[0205] Furthermore, in the case of conventional clamping motors, when used in high-cycle conditions, the mold is opened and closed continuously in a short period of time, which can cause the integrated current to exceed the protection current threshold, leading to abnormal shutdown. Moreover, in the case of multi-toggle clamping, the proportion of motor torque is high, which can also cause the integrated current to exceed the protection current threshold, leading to abnormal shutdown.

[0206] In contrast, the control device 700 according to the above-described embodiment and modified example changes the first protection current threshold and the second protection current threshold corresponding to the mold clamping motor 160. This makes it possible to prevent the integrated current value from exceeding one or more of the first protection current threshold and the second protection current threshold, even when mold opening and closing are operated continuously in a short period of time, or when the proportion of motor torque is high during mold clamping, such as in multi-toggle systems.

[0207] In the embodiments and modifications described above, the first protective current threshold and the second protective current threshold are changed based on the motor speed. For example, when the injection molding machine 10 produces molded products, the screw 330 may rotate at a low speed and high torque may be required. In the embodiments and modifications described above, when the motor speed is low, the first protective current threshold and the second protective current threshold are changed to a higher value, enabling the motor to output high torque, thus making it possible to produce molded products that would otherwise have stopped abnormally.

[0208] Preferred embodiments of the present disclosure have been described above. However, the inventions of the present disclosure are not limited to the embodiments described above. Various modifications, substitutions, etc., can be applied to the embodiments described above without departing from the scope of the inventions of the present disclosure. Furthermore, each of the features described with reference to the embodiments described above may be combined as appropriate, as long as they do not contradict each other technically. [Explanation of Symbols]

[0209] 10 injection molding machine 1301, 1301A motor 1302 Motor Encoder 1303 IPM 1304 Current detector 1305 Temperature Sensor 700 Control Unit 702 Storage medium 721 First protection current threshold memory unit 722 Second protection current threshold memory unit 701 CPU 1701 Motor control command generation unit 1702 Output Control Unit 1703 Current command generation section 1704 Current detection value input section 1705 Temperature input section 1706 Rotation speed input section 1707 1st update part 1708 2nd update part 1709 First Current Integration Unit 1710 Second Current Integration Unit 1711 First Comparative Section 1712 Second Comparative Section 1713 Anomaly Control Unit

Claims

1. The current value flowing through the motor installed in the injection molding machine is obtained from the detection unit. While the injection molding machine is continuously molding the molded product, the current value detected by the motor is accumulated for a predetermined period of time to calculate the cumulative value. The system includes a control unit that stops molding by the injection molding machine based on the cumulative value and a predetermined value, The control unit further changes the predetermined value while the injection molding machine is continuously molding molded products. Control device for an injection molding machine.

2. The control unit further changes the predetermined value during one shot in which the injection molding machine molds the product. The control device for an injection molding machine according to claim 1.

3. The control unit further changes the predetermined value between the first shot in which the injection molding machine molds the first molded product and the second shot in which it molds the second molded product. The control device for an injection molding machine according to claim 1.

4. When the motor is being cooled using a refrigerant, the control unit changes the predetermined value based on the temperature of the refrigerant detected by the first detection unit. The control device for an injection molding machine according to claim 1.

5. The control unit changes the predetermined value based on the external temperature of the motor detected by the second detection unit when the motor is air-cooled. A control device for an injection molding machine according to claim 1.

6. The control unit holds information that determines the predetermined value based on the status of the injection molding machine, When the status of the injection molding machine is obtained, the predetermined value is determined based on the obtained status and the information. The control device for an injection molding machine according to claim 1.

7. The control unit changes the predetermined value based on the rotational speed of the motor detected by the third detection unit. A control device for an injection molding machine according to claim 1.

8. The control unit, when the motor is a metering motor for rotating a screw provided in the injection molding machine, changes the predetermined value according to the volume of molding material poured into the mold device or the position where metering by the screw is completed. A control device for an injection molding machine according to claim 1.

9. The control unit, when the motor is a metering motor for rotating a screw provided in the injection molding machine, changes the predetermined value based on at least one of the following: the rotational speed of the screw, the type of molding material used to mold the molded product, the temperature of the molding material present in the cylinder provided in the injection molding machine, the temperature of the cylinder provided in the injection molding machine, and the type of screw. A control device for an injection molding machine according to claim 1.

10. The control device is provided according to any one of claims 1 to 9. Injection molding machine.

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