Injection molding machine

Abstract

This injection molding machine comprises: a fixed platen to which a fixed mold is attached; a movable platen to which a movable mold is attached; a mold clamping device that performs a mold closing process for bringing the movable platen into contact with the fixed platen by moving the movable platen by fluid pressure; and a control unit that controls the mold clamping device. The control unit comprises: a speed control unit that controls the speed of the movable platen in the mold closing process; an acquisition unit that acquires a pressure value indicating the fluid pressure caused by the movement of the movable platen; and a determination unit that determines whether the pressure value acquired by the acquisition unit exceeds a predetermined threshold value or not.

Description

[Technical field]

[0001] The present invention relates to an injection molding machine. [Background technology]

[0002] In an injection molding machine, a mold closing process is performed in which a fixed mold and a movable mold, which constitute a mold device for molding a molded product, are brought into contact with each other. A technique has been proposed in which a hydraulic cylinder is used as a mold clamping device for moving the movable mold during the mold closing process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP2006-015553A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes a technique for the mold opening process when a hydraulic cylinder is used in the mold clamping device. Specifically, in the mold opening process, the torque is limited and the time element is monitored to detect whether there is an abnormality.

[0005] When a hydraulic cylinder is used in the mold clamping device, in the mold closing process, if control is performed to move the movable platen, the torque or pressure is limited to a low level and the time element is monitored to detect whether or not there is an abnormality. In this control, since the torque or pressure is limited to a low level, the mold closing time until the mold closing process is completed varies greatly due to the influence of loads such as friction. For this reason, the monitoring time (time element) for determining whether or not there is an abnormality must be set long with a considerable margin of error.

[0006] Therefore, during the mold closing process, if a foreign object is caught between the fixed mold and the movable mold when it is being determined whether the mold closing process has been completed within the monitoring time, a load will continue to be applied to the mold device until the monitoring time has elapsed.

[0007] One aspect of the present invention provides a technique that enables rapid detection of an abnormality when controlling the speed of a movable platen during a mold closing process. [Means for solving the problem]

[0008] An injection molding machine according to one aspect of the present invention includes a stationary platen to which a stationary mold is attached, a movable platen to which a movable mold is attached, and a mold clamping device that performs a mold closing step of moving the movable platen by fluid pressure to bring the movable platen into contact with the stationary platen; a hydraulic cylinder that generates fluid pressure, a flow path that connects a plurality of oil chambers of the hydraulic cylinder, a bi-directional rotary pump provided in the middle of the flow path, and a servo motor that controls the rotation of the bi-directional rotary pump; and a control unit that controls the mold clamping device. The mold clamping device can switch the flow of oil through the flow passage based on the rotation direction of the biaxially rotating pump. The control unit includes a speed control unit that controls the speed of the movable platen in the mold closing process, an acquisition unit that acquires a pressure value indicating a fluid pressure generated by the movement of the movable platen, and a determination unit that determines whether the pressure value acquired by the acquisition unit exceeds a predetermined threshold value. a motor control unit that controls an output of a servo motor in response to the pressure value; has. Effect of the Invention

[0009] According to one aspect of the present invention, when controlling the speed of the movable platen, a change in fluid pressure caused by the movement of the movable platen is detected, thereby enabling rapid detection of an abnormality. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a state when mold opening of an injection molding machine according to an embodiment is completed. [Diagram 2] FIG. 2 is a diagram showing a state during mold clamping of the injection molding machine according to one embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a mold clamping device according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing components of the control device according to the first embodiment in the form of functional blocks. [Diagram 5] FIG. 5 is a diagram illustrating an example of pressure control in the pressure control unit of the control device according to the first embodiment. [Figure 6]FIG. 6 is a diagram showing an example of speed control in the speed control unit according to the first embodiment. [Figure 7] FIG. 7 is a flowchart showing a process for performing speed control in the mold closing process of the control device according to the first embodiment. [Figure 8] FIG. 8 is a diagram showing an example of speed control in the speed control section according to the first modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and the description thereof may be omitted.

[0012] Fig. 1 is a diagram showing a state of an injection molding machine according to an embodiment when mold opening is completed. Fig. 2 is a diagram showing a state of an injection molding machine according to an embodiment when mold clamping is performed. In this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction. When the mold clamping device 100 is of a horizontal type, the X-axis direction is the mold opening / closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side of the Y-axis direction is called the operation side, and the positive side of the Y-axis direction is called the anti-operation side.

[0013] As shown in FIG. 1 and FIG. 2, the injection molding machine 10 includes a clamping device 100 that opens and closes a mold device 800, an injection device 300 that injects a molding material into the mold device 800, a moving device 400 that moves the injection device 300 forward and backward relative to the mold device 800, a control device 700 that controls each component of the injection molding machine 10, and a frame 900 that supports each component of the injection molding machine 10. The injection molding machine 10 also includes an ejector device (not shown) that ejects a molded product molded by the mold device 800 from the mold device 800 (movable mold 820). The frame 900 includes a clamping device frame 910 that supports the clamping device 100, and an injection device frame 920 that supports the injection device 300. The clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via a leveling adjuster 930. The control device 700 is disposed in the internal space of the injection device frame 920. Each component of the injection molding machine 10 will now be described.

[0014] (mold clamping device) In the description of the clamping unit 100, the moving direction of the movable platen 120 during mold closing (for example, the positive direction of the X-axis) is the front, and the moving direction of the movable platen 120 during mold opening (for example, the negative direction of the X-axis) is the rear.

[0015] The mold clamping device 100 performs a mold closing process, a pressure increase process, a mold clamping process, a pressure release process, and a mold opening process of the mold device 800. The mold device 800 includes a fixed mold 810, a movable mold 820, and a movable member 830 that is arranged inside (hollow portion of) the movable mold 820 so as to be capable of moving forward and backward.

[0016] The mold clamping apparatus 100 is, for example, a horizontal type, and the mold opening and closing direction is horizontal. The mold clamping apparatus 100 includes a fixed platen 110, a movable platen 120, tie bars 140, a hydraulic cylinder 150, and the like.

[0017] The stationary platen 110 is fixed to the mold clamping unit frame 910. A stationary mold 810 is attached to the surface of the stationary platen 110 that faces the movable platen 120.

[0018] The movable platen 120 is disposed so as to be movable in the mold opening / closing direction relative to the mold clamping unit frame 910. A guide 101 for guiding the movable platen 120 is laid on the mold clamping unit frame 910. A movable mold 820 is attached to the surface of the movable platen 120 facing the fixed platen 110. By moving the movable platen 120 back and forth relative to the fixed platen 110, the mold closing process, pressure increase process, mold clamping process, depressurization process, and mold opening process of the mold apparatus 800 are performed.

[0019] The tie bars 140 connect the fixed platen 110 and a cylinder body 151 (see FIG. 3) of the hydraulic cylinder 150 at intervals L in the mold opening / closing direction. A plurality of tie bars 140 (for example, four) may be used. The plurality of tie bars 140 are arranged parallel to the mold opening / closing direction and extend according to the mold clamping force.

[0020] The hydraulic cylinder 150 is attached to the movable platen. The hydraulic cylinder 150 drives the movable platen 120 by a so-called direct pressure system, and moves the movable platen 120 in the mold opening and closing direction. The configuration of the hydraulic cylinder 150 and the details of the drive mechanism will be described later (see FIG. 3).

[0021] The mold clamping unit 100 performs a mold closing process, a pressure increase process, a mold clamping process, a pressure release process, a mold opening process, and the like under the control of the control device 700.

[0022] In the mold closing process, the hydraulic cylinder 150 (piston portion 152 described below) is driven to advance to a mold closing completion position at a set moving speed, thereby moving the movable platen 120 forward and bringing the movable mold 820 into contact with the fixed mold 810. The position and moving speed of the hydraulic cylinder 150 are detected using, for example, a cylinder pressure sensor. The cylinder pressure sensor detects the extension / retraction position of the hydraulic cylinder 150 and sends a signal indicating the detection result to the control device 700. As a result, the control device 700 can perform feedback control (position control of the hydraulic cylinder 150) regarding the position of the hydraulic cylinder 150 (movable platen 120) based on the signal indicating the detection result of the cylinder pressure sensor during the mold clamping process and the mold opening process described below.

[0023] The hydraulic cylinder position detector that detects the position of the hydraulic cylinder 150 and the hydraulic cylinder movement speed detector that detects the movement speed of the hydraulic cylinder 150 are not limited to cylinder pressure sensors, and general types may be used.

[0024] In the pressurizing process, the hydraulic cylinder 150 is further driven to control the pressure of the hydraulic cylinder 150 to a predetermined pressure (hereinafter, "target clamping pressure"), and the pressure of the hydraulic cylinder 150 is increased to generate a clamping force. The pressure of the hydraulic cylinder 150 is detected, for example, using a pressure sensor (cylinder pressure sensor) or the like provided in the hydraulic cylinder 150. The cylinder pressure sensor detects the pressure of a predetermined oil chamber inside the hydraulic cylinder 150 (for example, an oil chamber 155 described below), and sends a signal indicating the detection result to the control device 700. As a result, the control device 700 can perform feedback control of the pressure of the hydraulic cylinder 150 (pressure control of the hydraulic cylinder 150) based on the signal indicating the detection result of the cylinder pressure sensor in the pressurizing process, as well as the clamping process and depressurizing process described below.

[0025] In the mold clamping process, the hydraulic cylinder 150 is driven to maintain the pressure of the hydraulic cylinder 150 at a target mold clamping pressure. In the mold clamping process, the mold clamping force generated in the pressure increase process is maintained. In the mold clamping process, a cavity space 801 (see FIG. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with liquid molding material. The filled molding material is solidified to obtain a molded product.

[0026] The number of cavity spaces 801 may be one or more. In the latter case, multiple molded products are obtained at the same time. An insert material may be placed in a part of the cavity space 801, and another part of the cavity space 801 may be filled with a molding material. A molded product in which the insert material and the molding material are integrated is obtained.

[0027] In the depressurization step, the hydraulic cylinder 150 is driven to reduce the hydraulic cylinder 150 from the target clamping pressure, thereby reducing the clamping force.

[0028] In the mold opening process, the hydraulic cylinder 150 is driven to move the hydraulic cylinder 150 (piston portion 152) backward at a set moving speed from the mold opening start position to the mold opening completion position, thereby moving the movable platen 120 backward and separating the movable mold 820 from the fixed mold 810. After that, the ejector device ejects the molded product from the movable mold 820. The mold opening start position and the mold closing completion position may be the same position.

[0029] The set conditions in the mold closing process, the pressure increase process, and the mold clamping process are set together as a series of set conditions. For example, the moving speed, position (including the mold closing start position, the moving speed switching position, the mold closing completion position, and the mold clamping position), pressure (including the target mold clamping pressure), mold clamping force, etc. of the hydraulic cylinder 150 in the mold closing process and the pressure increase process are set together as a series of set conditions. The mold closing start position, the moving speed switching position, the mold closing completion position, and the mold clamping position are arranged in this order from the rear side to the front, and represent the start point and the end point of the section in which the moving speed is set. The moving speed is set for each section. There may be one or more moving speed switching positions. The moving speed switching position does not have to be set. Only one or two of the mold clamping position, the target mold clamping pressure, and the mold clamping force may be set.

[0030] The setting conditions in the depressurization process and mold opening process are set in the same manner. For example, the movement speed and position of the hydraulic cylinder 150 in the depressurization process and 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 the front to the rear, 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. The movement speed switching position does not have to be set. The mold opening start position and the mold closing completion position may be the same position. Furthermore, the mold opening completion position and the mold closing start position may be the same position.

[0031] Note that the moving speed and position of the movable platen 120 may be set instead of the moving speed and position of the hydraulic cylinder 150. Also, instead of the position of the hydraulic cylinder 150 (e.g., the mold clamping position) or the position of the movable platen 120, a target mold clamping pressure or mold clamping force may be set.

[0032] Although the mold clamping apparatus 100 of this embodiment is of a horizontal type in which the mold opening and closing direction is horizontal, it may be of a vertical type in which the mold opening and closing direction is vertical.

[0033] (Ejector device) In describing the ejector device, similarly to the description of the mold clamping device 100, the direction of movement of the movable platen 120 when the mold is closed (e.g., the positive direction of the X-axis) is defined as the front, and the direction of movement of the movable platen 120 when the mold is opened (e.g., the negative direction of the X-axis) is defined as the rear.

[0034] The ejector unit is attached to the movable platen 120 and moves forward and backward together with the movable platen 120. The ejector unit has an ejector rod that ejects a molded product from the mold device 800, and a drive mechanism that moves the ejector rod in the moving direction of the movable platen 120 (X-axis direction).

[0035] The ejector rod comes into contact with a movable member 830 that is arranged inside the movable mold 820 so as to be able to move forward and backward, and can move the movable member forward.

[0036] The drive mechanism 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. 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.

[0037] The ejector unit performs an ejection process under the control of the control unit 700. In the ejection process, the ejector unit advances the movable member 830 to eject the molded product.

[0038] The position and moving speed of the ejector rod are detected, for example, by 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. In addition, the ejector rod position detector that detects the position of the ejector rod and the ejector rod moving speed detector that detects the moving speed of the ejector rod are not limited to the ejector motor encoder, and general detectors can be used.

[0039] (injection device) In the description of the injection device 300, unlike the description of the mold clamping device 100 and the description of the ejector device 200, the movement direction of the screw 330 during filling (e.g., the negative X-axis direction) is described as the forward direction, and the movement direction of the screw 330 during metering (e.g., the positive X-axis direction) is described as the rearward direction.

[0040] The injection device 300 is mounted on a slide base 301, and the slide base 301 is disposed so as to be movable forward and backward with respect to an injection device frame 920. The injection device 300 is disposed so as to be movable forward and backward with respect to a mold device 800. The injection device 300 touches the mold device 800, and fills a cavity space 801 in the mold device 800 with molding material. The injection device 300 has, for example, a cylinder 310, a nozzle 320, a screw 330, a metering motor 340, an injection motor 350, a load detector 360, and the like.

[0041] Cylinder 310 heats the molding material supplied to the inside from supply port 311. The molding material includes, for example, resin. The molding material is formed, for example, in the shape of pellets, and is supplied to supply port 311 in a solid state. Supply port 311 is formed at the rear of cylinder 310. A cooler 312 such as a water-cooled cylinder is provided on the outer periphery of the rear of cylinder 310. A heater 313 such as a band heater and a temperature detector 314 are provided on the outer periphery of cylinder 310, forward of cooler 312.

[0042] Cylinder 310 is divided into a plurality of zones in the axial direction (e.g., X-axis direction) of cylinder 310. Each of the plurality of zones is provided with heater 313 and temperature detector 314. A set temperature is set for each of the plurality of zones, and control device 700 controls heater 313 so that the detected temperature of temperature detector 314 becomes the set temperature.

[0043] The nozzle 320 is provided 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 periphery of the nozzle 320. The control device 700 controls the heater 313 so that the detected temperature of the nozzle 320 becomes the set temperature.

[0044] The screw 330 is disposed in the cylinder 310 so as to be rotatable and movable forward and backward. When the screw 330 is rotated, the molding material is sent forward along the spiral groove of the screw 330. As the molding material is sent forward, it is gradually melted by heat from the cylinder 310. As the liquid molding material is sent forward of the screw 330 and accumulates in the front part of the cylinder 310, the screw 330 is moved backward. Thereafter, when the screw 330 is moved forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled into the mold device 800.

[0045] A check ring 331 is attached to the front of the screw 330 so as to be movable back and forth as a check valve for preventing the backflow of molding material from the front to the rear of the screw 330 when the screw 330 is pushed forward.

[0046] When the screw 330 is moved forward, the backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and moves backward relatively to the screw 330 to a blocking position (see FIG. 2) where the flow path of the molding material is blocked. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

[0047] 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 sent forward along the spiral groove of the screw 330, and moves forward relatively to the screw 330 to an open position (see FIG. 1) where the flow path of the molding material is opened. As a result, the molding material is sent forward of the screw 330.

[0048] 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.

[0049] The injection device 300 may have a drive source for moving the backflow prevention ring 331 back and forth between the open position and the closed position relative to the screw 330.

[0050] The metering motor 340 rotates the screw 330. The drive source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump.

[0051] The injection motor 350 advances and retreats the screw 330. A motion conversion mechanism that converts the rotational motion of the injection motor 350 into the linear motion of the screw 330 is provided between the injection motor 350 and the screw 330. The motion conversion mechanism has, for example, a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be provided between the screw shaft and the screw nut. The drive source that advances and retreats the screw 330 is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder.

[0052] The load detector 360 detects the force transmitted between the injection motor 350 and the screw 330. The detected force is converted into pressure by the control device 700. The load detector 360 is provided on a force transmission path between the injection motor 350 and the screw 330, and detects the force acting on the load detector 360.

[0053] The load detector 360 sends a signal indicating the detection result to the control device 700. The detection result of the load detector 360 is used to control and monitor the pressure that the screw 330 receives from the molding material, the back pressure on the screw 330, the pressure that the screw 330 exerts on the molding material, and the like.

[0054] The pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a general detector may be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320. The mold internal pressure sensor is installed inside the mold device 800.

[0055] The injection device 300 performs a metering process, a filling process, a pressure holding process, and the like under the control of the control device 700. The filling process and the pressure holding process may be collectively referred to as the injection process.

[0056] In the metering process, the metering motor 340 is driven to rotate the screw 330 at a set rotation speed, and the molding material is sent forward along the spiral groove of the screw 330. As a result, the molding material is gradually melted. As the liquid molding material is sent forward of the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is moved backward. The rotation speed of the screw 330 is detected, for example, by using a metering motor encoder 341. The metering motor encoder 341 detects the rotation of the metering motor 340 and sends a signal indicating the detection result to the control device 700. In addition, the screw rotation speed detector that detects the rotation speed of the screw 330 is not limited to the metering motor encoder 341, and a general one can be used.

[0057] In the metering process, in order to restrict abrupt retraction of the screw 330, the injection motor 350 may be driven to apply a set back pressure to the screw 330. The back pressure on the screw 330 is detected, for example, by using a load detector 360. The load detector 360 sends a signal indicating the detection result to the control device 700. When the screw 330 retracts to the metering completion position and a predetermined amount of molding material is accumulated in front of the screw 330, the metering process is completed.

[0058] The position and rotation speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, a metering start position, a rotation speed switching position, and a metering completion position are set. These positions are arranged in this order from the front to the rear, and represent the start and end points of the section in which the rotation speed is set. The rotation speed is set for each section. There may be one or more rotation speed switching positions. The rotation speed switching position does not have to be set. In addition, a back pressure is set for each section.

[0059] In the filling step, the injection motor 350 is driven to move the screw 330 forward at a set moving speed, and the liquid molding material accumulated in front of the screw 330 is filled into the cavity space 801 in the mold device 800. The position and moving speed of the screw 330 are detected, for example, by 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 a set position, switching from the filling step to the pressure holding step (so-called V / P switching) is performed. The position where the V / P switching is performed is also called the V / P switching position. The set moving speed of the screw 330 may be changed depending on the position of the screw 330, time, etc.

[0060] The position and movement speed of the screw 330 in the filling process are set together as a series of setting conditions. For example, a filling start position (also called an "injection start position"), a movement speed switching position, and a V / P switching position are set. These positions are arranged in this order from the rear side to the front, and represent the start and end points of the section for 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 do not have to be set.

[0061] An upper limit value for the pressure of the screw 330 is set for each section in which the moving speed of the screw 330 is set. The pressure of the screw 330 is detected by the load detector 360. When the detected value of the load detector 360 is equal to or lower than the set pressure, the screw 330 is advanced at the set moving speed. On the other hand, when the detected value of the load detector 360 exceeds the set pressure, the screw 330 is advanced at a moving speed slower than the set moving speed so that the detected value of the load detector 360 is equal to or lower than the set pressure, in order to protect the die.

[0062] After the position of the screw 330 reaches the V / P switching position in the filling process, the screw 330 may be temporarily stopped at the V / P switching position, and then the V / P switching may be performed. Immediately before the V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed. Furthermore, 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, and general detectors may be used.

[0063] In the holding pressure step, the injection motor 350 is driven to push the screw 330 forward, and the pressure of the molding material at the front end of the screw 330 (hereinafter also referred to as "holding pressure") is maintained at a set pressure, and the molding material remaining in the cylinder 310 is pushed toward the mold device 800. The molding material that is insufficient due to cooling contraction in the mold device 800 can be replenished. The holding pressure is detected, for example, by a load detector 360. The load detector 360 sends a signal indicating the detection result to the control device 700. The set value of the holding pressure may be changed depending on the elapsed time from the start of the holding pressure step, etc. The holding pressure and the holding time for which the holding pressure is held in the holding pressure step may each be set multiple times, or may be set collectively as a series of setting conditions.

[0064] In the dwelling step, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and when the dwelling step is completed, the entrance to the cavity space 801 is blocked by the solidified molding material. This state is called a gate seal, and prevents the molding material from flowing back from the cavity space 801. After the dwelling step, the cooling step is started. In the cooling step, the molding material in the cavity space 801 is solidified. A measuring step may be performed during the cooling step in order to shorten the molding cycle time.

[0065] The injection device 300 of this embodiment is of an in-line screw type, but may be of a pre-plastication type or the like. A pre-plastication type injection device supplies molding material molten in a plasticization cylinder to an injection cylinder, and injects the molding material from the injection cylinder into a mold device. A screw is disposed in the plasticization cylinder so as to be rotatable but unable to move forward or backward, or a screw is disposed so as to be rotatable and able to move forward or backward. Meanwhile, a plunger is disposed in the injection cylinder so as to be able to move forward or backward.

[0066] Furthermore, the injection device 300 of this embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, but may be a vertical type in which the axial direction of the cylinder 310 is vertical. A mold clamping device to be combined with the vertical injection device 300 may be either a vertical type or a horizontal type. Similarly, a mold clamping device to be combined with the horizontal injection device 300 may be either a horizontal type or a vertical type.

[0067] As described above, in this embodiment, the injection unit 300 is electrically driven by electric actuators such as the metering motor 340 and the injection motor 350. This allows the injection unit 300 to have relatively higher responsiveness to control commands from the control device 700 than when the injection unit 300 is hydraulically driven. Therefore, the injection molding machine 10 can achieve relatively excellent controllability of the injection unit 300.

[0068] (Mobile device) In the description of the moving device 400, similar to the description of the injection device 300, the moving direction of the screw 330 during filling (for example, the negative X-axis direction) is the front, and the moving direction of the screw 330 during metering (for example, the positive X-axis direction) is the rear.

[0069] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. In addition, the moving device 400 presses the nozzle 320 against the mold device 800 to generate a 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.

[0070] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a pump that can rotate in both directions, and by switching the rotation direction of the motor 420, it draws in hydraulic fluid (e.g., oil) from one of the first port 411 and the second port 412 and discharges it from the other, thereby generating hydraulic pressure. The hydraulic pump 410 can also draw in hydraulic fluid from a tank and discharge the hydraulic fluid from one of the first port 411 and the second port 412.

[0071] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 with a rotational direction and rotational torque according to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servo motor.

[0072] The hydraulic cylinder 430 has 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.

[0073] A front chamber 435 of the hydraulic cylinder 430 is connected to a first port 411 of the hydraulic pump 410 via a first flow path 401. The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 via the first flow path 401, thereby pushing the injection unit 300 forward. The injection unit 300 is moved forward, and the nozzle 320 is pressed against the fixed die 810. The front chamber 435 functions as a pressure chamber that generates a nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0074] On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via the second flow path 402. The hydraulic fluid discharged from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402, thereby pushing the injection unit 300 backward. The injection unit 300 is moved backward, and the nozzle 320 is separated from the fixed mold 810.

[0075] In this embodiment, the moving device 400 includes the hydraulic cylinder 430, but the present invention is not limited to this. 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.

[0076] (Control device) The control device 700 is configured, for example, by a computer, and has a CPU (Central Processing Unit) 701, a storage medium 702 such as a memory, an input interface 703, and an output interface 704 as shown in Fig. 1 and Fig. 2. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. The control device 700 also receives signals from the outside via the input interface 703, and transmits signals to the outside via the output interface 704.

[0077] The control device 700 repeatedly performs a metering process, a mold closing process, a pressure increase process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure release process, a mold opening process, and an ejection process, etc., to repeatedly manufacture molded products. A series of operations to obtain a molded product, for example, an operation from the start of a metering process to the start of the next metering process, is also called a "shot" or a "molding cycle." The time required for one shot is also called a "molding cycle time" or a "cycle time."

[0078] One molding cycle includes, for example, a metering process, a mold closing process, a pressure increase process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure release process, a mold opening process, and an ejection process, in this order. The order here refers to the order in which each process starts. The filling process, the pressure holding process, and the cooling process are performed during the mold clamping process. The start of the mold clamping process may coincide with the start of the filling process. The end of the pressure release process coincides with the start of the mold opening process.

[0079] In addition, in order to shorten the molding cycle time, a plurality of processes may be performed simultaneously. 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 be started during the mold closing process. The ejection process may be started during the mold opening process. In the case where an opening / closing valve for opening and closing the flow path of the nozzle 320 is provided, 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, the molding material will not leak from the nozzle 320 as long as the opening / closing valve closes the flow path of the nozzle 320.

[0080] Note that one molding cycle may include steps other than the metering step, mold closing step, pressure increase step, mold clamping step, filling step, pressure holding step, cooling step, pressure release step, mold opening step, and ejection step.

[0081] For example, after the dwelling step is completed, a pre-metering suck-back step may be performed in which the screw 330 is retracted to a preset metering start position before the metering step is started. This can reduce the pressure of the molding material accumulated in front of the screw 330 before the metering step starts, and can prevent the screw 330 from suddenly retracting at the start of the metering step.

[0082] Furthermore, after the metering step is completed, a post-metering suck-back step may be performed in which the screw 330 is retracted to a preset filling start position (also called the "injection start position") before the filling step is started. This can reduce the pressure of the molding material accumulated in front of the screw 330 before the filling step is started, and can prevent the molding material from leaking from the nozzle 320 before the filling step is started.

[0083] The control device 700 is connected to an operation device 750 that accepts input operations by a user and a display device 760 that displays a screen. The operation device 750 and the display device 760 may be configured, for example, by a touch panel 770 and may be integrated. The touch panel 770 as the display device 760 displays a screen under the control of the control device 700. For example, the screen of the touch panel 770 may display information such as the settings of the injection molding machine 10 and the current state of the injection molding machine 10. In addition, for example, an operation unit such as a button that accepts an input operation by a user and an input field may be displayed on the screen of the touch panel 770. The touch panel 770 as the operation device 750 detects an input operation on the screen by the user and outputs a signal corresponding to the input operation to the control device 700. Thereby, for example, the user can operate the operation unit provided on the screen while checking the information displayed on the screen to perform settings of the injection molding machine 10 (including input of a setting value). In addition, the user can operate the operation unit provided on the screen to perform an operation of the injection molding machine 10 corresponding to the operation unit. The operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the clamping device 100, the ejector device 200, the injection device 300, the moving device 400, etc. The operation of the injection molding machine 10 may be the switching of a screen displayed on the touch panel 770 serving as the display device 760, etc.

[0084] In this embodiment, the operation device 750 and the display device 760 are described as being integrated as the touch panel 770, but they may be provided independently. Also, a plurality of operation devices 750 may be provided. The operation device 750 and the display device 760 are disposed on the operation side (Y-axis negative direction) of the mold clamping unit 100 (more specifically, the fixed platen 110).

[0085] (First embodiment) Next, the details of the mold clamping device 100 will be described with reference to FIG.

[0086] Fig. 3 is a diagram showing an example of the mold clamping apparatus 100 according to this embodiment. Specifically, Fig. 3 is a diagram showing an operating state of the mold clamping apparatus 100 in a mold closing process. Note that in Fig. 3, the illustration of the mold apparatus 800 is omitted.

[0087] As shown in FIG. 3, the mold clamping unit 100 includes a fixed platen 110, a movable platen 120, tie bars 140, a hydraulic cylinder 150, a hydraulic circuit 160, and a servo motor 170.

[0088] The hydraulic cylinder 150 includes a cylinder body portion 151 , a piston portion 152 , a rod portion 153 , and a cylinder closing portion 154 .

[0089] The cylinder main body 151 is a fixed part of the hydraulic cylinder 150. The cylinder main body 151 is connected to one end of a tie bar 140, the other end of which is connected to the fixed platen 110. This fixes the distance between the cylinder main body 151 and the fixed platen 110 at a constant value (distance L). The cylinder main body 151 is provided with a hollow part whose front end (the end in the negative direction of the X-axis) is open.

[0090] One of the cylinder main body 151 and the fixed platen 110, which are connected via the tie bar 140, is fixed to the mold clamping unit frame 910, and the other is movably placed on the mold clamping unit frame 910. This makes it possible to allow the tie bar 140 to elongate due to the generation of the mold clamping force.

[0091] One end of the piston portion 152 is inserted into the interior (hollow portion) of the cylinder main body portion 151, and the other end is fixed to the movable platen 120. This allows the piston portion 152 to move in the front-to-rear direction (X direction) by the action of the working oil supplied to and discharged from the cylinder main body portion 151, and as a result, the movable platen 120 fixed to one end of the piston portion 152 can be moved in the front-to-rear direction (X direction). Also, the piston portion 152 is provided with a hollow portion that is open to the interior side of the cylinder main body portion 151.

[0092] One end of the rod portion 153 is fixed to a closed end (i.e., the end in the negative direction of the X-axis) of the hollow portion of the cylinder main body portion 151, and the other end is inserted into the hollow portion of the piston portion 152. This allows the rod portion 153 to move the piston portion 152 forward (in the positive direction of the X-axis) by the action of hydraulic oil supplied to the hollow portion of the piston portion 152 (oil chamber 157 described below). Also, the rod portion 153 is provided with a hole portion extending in the axial direction from the other end side inserted into the hollow portion of the piston portion 152.

[0093] The cylinder closing portion 154 closes the open end of the cylinder main body portion 151. The cylinder closing portion 154 is provided with a through hole through which the piston portion 152 passes and is capable of advancing and retreating.

[0094] Moreover, oil chambers 155 to 157 are provided inside the hydraulic cylinder 150.

[0095] The oil chamber 155 is provided at a closed end (end in the negative direction of the X-axis) of the hollow portion of the cylinder body 151, in a form partitioned by the inner wall of the cylinder body 151 and the tip (one end) of the piston 152. This enables the piston 152 to apply a clamping force to the movable platen 120 by the action of hydraulic oil supplied to the oil chamber 155. The oil chamber 155 is provided with a port 155P for supplying and discharging hydraulic oil.

[0096] This embodiment is a description of the mold closing process, and the hydraulic circuit that supplies and discharges the working oil to the oil chamber 155 for applying the mold clamping force may be the same as a conventional hydraulic circuit, so the description will be omitted.

[0097] The oil chamber 156 is provided at the open end (end in the positive direction of the X-axis) of the cylinder main body 151, in a form partitioned by the inner wall of the cylinder main body 151, the inner wall of the cylinder closing portion 154, and a middle portion of the piston portion 152. This allows the piston portion 152 to move backward (i.e., move in the negative direction of the X-axis) by the action of the hydraulic oil supplied to the oil chamber 156. The oil chamber 156 is provided with a port 156P for supplying and discharging the hydraulic oil.

[0098] Oil chamber 157 is provided in a form partitioned by the inner wall of the hollow portion of piston portion 152 and the tip end of rod portion 153. This allows piston portion 152 to move forward (i.e., move in the positive direction of the X-axis) by the action of hydraulic oil supplied to oil chamber 157. Oil chamber 157 communicates with a hole in rod portion 153, and a port 157P is provided at the tip end of the hole in rod portion 153 for supplying and discharging hydraulic oil between oil chamber 157.

[0099] The hydraulic circuit 160 drives the hydraulic cylinder 150. The hydraulic circuit 160 includes a mold closing side relief valve 161, a mold opening side relief valve 162, an adjustment valve 163, a bidirectional rotary pump 164, a check valve 165, a check valve 166, a pressure sensor 167, a tank 168, and oil passages OL1 to OL3.

[0100] The oil passage OL1 connects the tank 168, the mold closing side relief valve 161, the mold opening side relief valve 162, the check valve 165, and the check valve 166.

[0101] The oil passage OL2 connects the supply / discharge port 157P of the oil chamber 157 to the bidirectional rotary pump 164. The oil passage OL2 is also connected to each of the mold closing side relief valve 161, the adjustment valve 163, and the check valve 165. A pressure sensor 167 is provided in the oil passage OL2 near the supply / discharge port 157P of the oil chamber 157.

[0102] The oil passage OL3 connects between the supply / discharge port 156P of the oil chamber 156 and the bidirectional rotary pump 164. In addition, the oil passage OL2 is connected to each of the mold-opening side relief valve 162, the adjustment valve 163, and the check valve 166.

[0103] The bidirectional pump 164 is provided on a flow path (oil passage OL2 and oil passage OL3) that connects between a plurality of oil chambers (oil chamber 157 and oil chamber 156) of the hydraulic cylinder 150 that generates fluid pressure. The bidirectional pump 164 according to this embodiment adjusts the flow direction and flow amount of the working oil flowing between the oil passage OL2 and the oil passage OL3 by being driven by the servo motor 170. In this way, the bidirectional pump 164 can discharge the working oil to either the oil passage OL2 or the oil passage OL3 based on the drive of the servo motor 170.

[0104] For example, the bidirectional rotary pump 164 discharges the working oil supplied from the oil passage OL2 to the oil passage OL3 based on the drive of the servo motor 170. This realizes a flow path through which the working oil flows from the supply / discharge port 157P of the oil chamber 157, via the oil passage OL2 and the oil passage OL3, in that order, to the supply / discharge port 156P of the oil chamber 156. This causes the piston portion 152 to move backward (i.e., move in the negative direction of the X-axis), thereby realizing the mold opening process in which the movable mold 820 is moved in the mold opening direction.

[0105] As another example, the bidirectional rotary pump 164 discharges the working oil supplied from the oil passage OL3 to the oil passage OL2 based on the drive of the servo motor 170. This realizes a flow path through which the working oil flows from the supply / discharge port 156P of the oil chamber 156, via the oil passage OL3 and the oil passage OL2, in that order, to the supply / discharge port 157P of the oil chamber 157. This causes the piston portion 152 to move forward (i.e., move in the positive direction of the X-axis), thereby realizing a mold closing process in which the movable mold 820 is moved in the mold closing direction.

[0106] The mold opening relief valve 162 is a relief valve provided in the oil passage OL3, and is a mechanical valve that switches between a connected state and a cut-off state based on the pressure of the working oil flowing through the oil passage OL3. For example, in the mold opening process, when the pressure in the oil passage OL3 reaches a predetermined level or higher, the mold opening relief valve 162 is in a connected state, and the working oil flowing through the oil passage OL3 is discharged to the tank 168 via the oil passage OL1.

[0107] The mold closing side relief valve 161 is a relief valve provided in the oil passage OL2, and is a mechanical valve that switches between a connected state and a cut-off state based on the pressure of the working oil flowing through the oil passage OL2. For example, in the mold closing process, when the pressure in the oil passage OL2 reaches a predetermined level or higher, the mold closing side relief valve 161 is in a connected state, and the working oil flowing through the oil passage OL2 is discharged to the tank 168 via the oil passage OL1.

[0108] The check valve 165 is a valve that unidirectionally controls the flow of hydraulic oil from the oil passage OL1 to the oil passage OL2 and prevents reverse flow. In the hydraulic circuit 160 of the present embodiment, the check valve 165 is provided so that the working oil is supplied from the tank 168 to the oil passage OL2.

[0109] The check valve 166 is a valve that unidirectionally controls the flow of hydraulic oil from the oil passage OL1 to the oil passage OL3 and prevents reverse flow. In the hydraulic circuit 160 of the present embodiment, the check valve 166 is provided so that the working oil is supplied from the tank 168 to the oil passage OL3.

[0110] The tank 168 stores hydraulic oil. The tank 168 is also connected to the mold opening side relief valve 162, the mold closing side relief valve 161, the check valve 165, and the check valve 166 through the oil passage OL1. In this way, the tank 168 stores the working oil discharged from the mold opening side relief valve 162 or the mold closing side relief valve 161 through the oil passage OL1. The tank 168 also supplies the stored working oil from the check valve 165 to the oil passage OL2, or from the check valve 166 to the oil passage OL3, through the oil passage OL1.

[0111] The adjusting valve 163 is a valve for adjusting the amount of oil in each of the oil passages OL2 and OL3 during the mold opening process and the mold closing process. By providing the adjusting valve 163, the passing flow rate can be adjusted to be constant during the mold opening process and the mold closing process.

[0112] The pressure sensor 167 is provided on the oil passage OL2 near the supply / discharge port 157P of the oil chamber 157 of the hydraulic cylinder 150, and detects the pressure acting on the oil chamber 157 of the hydraulic cylinder 150.

[0113] That is, in the hydraulic circuit controlling the hydraulic cylinder used conventionally, instead of the bidirectional rotary pump 164 capable of discharging the working oil in both directions, a variable pump capable of discharging the working oil in only one direction was often used. When such a variable pump was used, an electromagnetic switching valve (an example of a directional switching valve) was provided to switch the oil chamber to which the working oil was supplied. The mold opening process and mold closing process were realized by switching the oil chamber to which the working oil was supplied with this electromagnetic switching valve.

[0114] Conventional electromagnetic switching valves are often installed near the hydraulic cylinder. If a pressure sensor is installed in such a conventional hydraulic circuit, various parts that make up the electromagnetic switching valve will be between the hydraulic sensor and the hydraulic cylinder. Therefore, in conventional hydraulic circuits, it is difficult for the pressure sensor to detect the pressure applied to the oil chamber of the hydraulic cylinder.

[0115] In contrast, in the hydraulic circuit 160 of this embodiment, the discharge direction of the working oil from the bidirectional rotary pump 164 is switched according to the rotation direction of the servo motor 170, thereby switching the oil chamber to which the working oil is supplied. With this configuration, it becomes unnecessary to provide an electromagnetic contactor or the like between the hydraulic cylinder 150 and the pressure sensor 167. Furthermore, since the hydraulic circuit 160 according to this embodiment can reduce the number of components compared to conventional hydraulic circuits, the piping length of the hydraulic circuit 160 can be shortened compared to conventional circuits. Since the piping length can be shortened, the hydraulic circuit 160 can be formed of steel pipes. This makes it possible to reduce pressure changes due to disturbances.

[0116] The hydraulic circuit 160 that hydraulically drives the mold clamping device 100 (hydraulic cylinder 150) is configured as a closed circuit as described above. Moreover, in the hydraulic circuit 160 according to this embodiment, the pressure sensor 167 and the hydraulic cylinder 150 are directly connected by an oil passage OL2A (a part of the oil passage OL2). In the hydraulic circuit 160, pressure changes due to disturbances can also be reduced, so that the pressure sensor 167 can detect the pressure applied to the oil chamber 157 of the hydraulic cylinder 150 with high accuracy.

[0117] The hydraulic circuit 160 of this embodiment does not have an electromagnetic contactor and has a shorter piping length than conventional hydraulic circuits, so the amount of heat generated is small and the oil temperature is less likely to rise. This makes it possible to reduce the amount of hot water used in the hydraulic circuit 160. This allows the capacity of the tank 168 to be reduced, allowing the mold clamping unit 100 to be made compact.

[0118] The servo motor 170 operates based on the control of the control device 700, and controls the rotation of the bidirectional rotary pump 164. In this way, the control device 700 can control the operation of the bidirectional rotary pump 164 by controlling the servo motor 170.

[0119] The control device 700 controls the flow of hydraulic oil in the hydraulic circuit 160 by controlling the bidirectional rotary pump 164 (servo motor 170), and realizes the mold closing process and mold opening process by the mold clamping device 100. The control device 700 also realizes a pressure increase process, a mold clamping process, and a pressure release process by controlling the hydraulic circuit 160, but a description thereof will be omitted.

[0120] FIG. 4 is a diagram showing components of the control device 700 according to the first embodiment in the form of functional blocks. Each functional block shown in FIG. 4 is conceptual, and does not necessarily have to be physically configured as shown in the figure. All or a part of each functional block can be functionally or physically distributed and integrated in any unit. All or any part of each processing function performed by each functional block is realized by a program executed by the CPU 701. Alternatively, each functional block may be realized as hardware using wired logic. As shown in FIG. 4, the control device 700 includes an input processing unit 711, a pressure control unit 712, a speed control unit 713, a switching unit 714, an acquisition unit 715, a determination unit 716, a stop control unit 717, and a notification unit 718. The control device 700 also includes a threshold storage unit 710 on the storage medium 702.

[0121] The threshold value storage unit 710 stores a pressure threshold value used when performing speed control in the mold closing process.

[0122] The input processing unit 711 processes the input of a user's operation from the operation device 750 via the input interface 703. For example, the input processing unit 711 processes the input of a selection operation of either pressure control or speed control from the user when performing a mold closing process.

[0123] In this embodiment, when moving the movable platen in the mold closing process, a switching unit 714 switches between control of moving the movable platen 120 and the piston portion 152 under pressure control by a pressure control unit 712 and control of moving the movable platen 120 and the piston portion 152 under speed control by a speed control unit 713, based on a selection operation input and processed by an input processing unit 711. The pressure control unit 712 and the speed control unit 713 will be described later.

[0124] In the mold closing process, the pressure control unit 712 performs pressure control using the hydraulic cylinder 150. Fig. 5 is a diagram showing an example of pressure control in the pressure control unit 712. Fig. 5 shows a speed 1502 and a pressure 1501 of the piston portion 152.

[0125] In the example shown in Fig. 5, the mold closing process starts at the mold closing start time. The pressure control unit 712 controls the movable platen 120 together with the piston portion 152 of the hydraulic cylinder 150 so that the speed becomes V1. Then, after the piston portion 152 reaches the mold protection position, the pressure control unit 712 switches the control performed on the piston portion 152 from speed control to pressure control. Pressure control is a control that does not apply a pressure equal to or greater than a predetermined limit value, and is also called low pressure control. The predetermined limit value is a pressure value lower than the pressure applied from the start of mold closing until the arrival at the mold protection position.

[0126] The determination unit 716 determines whether the time taken for the movable platen 120 to reach the pressure increase start position (an example of a predetermined position) exceeds a monitoring time (an example of a predetermined time). In the example shown in Fig. 5, it is assumed that an abnormality occurs at time t1, such as a foreign object being trapped in the mold device 800. As a result, the speed 1502 of the movable platen 120 decreases together with the piston portion 152.

[0127] The determination unit 716 determines that an abnormality has occurred when the monitoring time t2 has passed. In this manner, no determination is made until the monitoring time t2 has passed since the foreign object was trapped, but the effect of the foreign object on the mold device 800 being less due to the low pressure control can be obtained.

[0128] The stop control unit 717 performs control to stop the servo motor 170 when the judgment unit 716 judges that the time taken to reach the boost start position (an example of a predetermined position) exceeds a monitoring time (an example of a predetermined time).

[0129] When the judgment unit 716 judges that the time taken to reach the pressure increase start position (an example of a predetermined position) has exceeded the monitoring time (an example of a predetermined time), the notification unit 718 notifies the operator using the injection molding machine 10, a monitoring center, etc., that an abnormality has occurred.

[0130] However, when the pressure applied to the piston portion 152 is reduced, as in the low pressure control by the pressure control portion 712, the pressure is easily affected by friction, etc., and the completion time of the mold closing process varies. Therefore, in the low pressure control by the pressure control portion 712, the monitoring time t2 is set with a margin. When determining whether or not an abnormality has occurred based on such monitoring time t2, it may take a long time to detect the abnormality.

[0131] Therefore, the control device 700 according to this embodiment enables speed control by a speed control section 713 instead of pressure control by a pressure control section 712 .

[0132] Returning to FIG. 4, the speed control unit 713 of this embodiment controls the speed of the hydraulic cylinder 150 that moves in the mold closing process, as well as the speed of the movable platen 120 that is fixed to the hydraulic cylinder 150.

[0133] Specifically, the speed control unit 713 of this embodiment controls the speed of the piston unit 152 and the movable platen 120 so that they move at a speed V1 from the start of the mold closing process until they reach the mold protection position. Then, after the piston unit 152 and the movable platen 120 reach the mold protection position, the speed control unit 713 controls the speed of the piston unit 152 and the movable platen 120 so that they move at a speed V2 (speed V2<speed V1) until they reach the pressure increase start position. When the speed control unit 713 controls the speed, it judges whether or not there is an abnormality based on the pressure value detected by the pressure sensor 167. That is, in this embodiment, since the above-mentioned hydraulic circuit 160 is provided, the detection accuracy of the pressure value is high, and therefore it is possible to judge whether or not there is an abnormality based on the pressure value.

[0134] Furthermore, feedback control may be incorporated into the speed control section 713 to control the speed of the piston portion 152 and the movable platen 120 so as to prevent variation.

[0135] The acquisition unit 715 acquires from the pressure sensor 167 a pressure value indicating the fluid pressure acting on the oil chamber 157 of the piston portion 152 due to the movement of the piston portion 152 and the movable platen 120 .

[0136] Furthermore, the acquisition unit 715 acquires the position of the piston portion 152 in the mold closing direction from a linear sensor (not shown) provided on the hydraulic cylinder 150. This makes it possible to recognize whether the piston portion 152 has reached the mold protection position or the temperature rise start position. The mold protection position is a position where the speed or pressure is reduced to protect the mold device 800. The temperature rise start position is a position (an example of a predetermined position) where the mold closing process is completed.

[0137] The determination unit 716 determines whether or not the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold value stored in the threshold value storage unit 710 .

[0138] Fig. 6 is a diagram showing an example of speed control in the speed control unit 713 according to this embodiment. Fig. 6 shows a speed 1601 of the piston portion 152 and a pressure value 1602 of the fluid pressure acquired by the acquisition unit 715.

[0139] 6, the mold closing process starts at the mold closing start time. The speed control unit 713 controls the movable platen 120 together with the piston portion 152 of the hydraulic cylinder 150 to move at a speed V1. Then, after the piston portion 152 reaches the mold protection position, the speed control unit 713 controls the movable platen 120 together with the piston portion 152 to move at a speed V2 (speed V2<speed V1). By moving the movable platen 120 at such a low speed, the movable mold 820 fixed to the movable platen 120 can be protected.

[0140] The acquiring unit 715 acquires a pressure value P2 that is lower than the pressure value P1 in accordance with the speed change caused by the speed control unit 713.

[0141] The threshold storage unit 710 stores a pressure threshold T1 required to reach the mold protection position and a pressure threshold T2 required to reach the pressure increase start position from the mold protection position for speed control by the speed control unit 713. In this manner, the threshold storage unit 710 stores predetermined pressure thresholds according to the positions to which the movable platen 120 and the piston portion 152 have moved.

[0142] The determination unit 716 determines whether the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold stored in the threshold storage unit 710. The determination unit 716 in this embodiment performs determination based on a predetermined pressure threshold for each position to which the movable platen 120 and the piston unit 152 are moved. Specifically, the determination unit 716 determines whether the acquired pressure value exceeds the pressure threshold T1 until the mold protection position is reached, and determines whether the acquired threshold exceeds the pressure threshold T2 from the mold protection position until the pressure increase start position is reached. In addition, in the case of speed control, similarly to pressure control, the determination unit 716 may determine whether an abnormality has occurred depending on whether the time until the pressure increase start position is reached exceeds a monitoring time.

[0143] 6, at time t3, the determination unit 716 determines that the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold value T2 stored in the threshold value storage unit 710. In this way, with the speed control of this embodiment, if a foreign object is caught, an abnormality determination can be made immediately.

[0144] When it is determined that the pressure value acquired by the determination unit 716 exceeds the pressure threshold value, the stop control unit 717 performs control to stop the servo motor 170. Note that, in this embodiment, a case where control to stop the servo motor 170 is described, but the present invention is not limited to the control to stop the servo motor 170, and it is also possible to perform control to rotate the servo motor 170 in the reverse direction, for example.

[0145] When the notification unit 718 determines that the pressure value acquired by the judgment unit 716 exceeds the pressure threshold value, it notifies the operator using the injection molding machine 10, a monitoring center, etc. that an abnormality has occurred.

[0146] 7 is a flow chart showing a process of speed control in the mold closing process of the control device 700 according to this embodiment. Note that the pressure control may be performed using a method similar to that of the prior art, and therefore a description thereof will be omitted.

[0147] First, the control device 700 judges whether or not the mold closing process by speed control has started (S701). When it is judged that the mold closing process by speed control has not started (S701: No), the process ends.

[0148] When the control device 700 determines that the mold closing process by speed control is to start (S701: Yes), the speed control section 713 controls the servo motor 170 to perform speed control so that the piston portion 152 moves at a speed V1 (S702).

[0149] The acquiring unit 715 acquires a pressure value indicating the fluid pressure acting on the oil chamber 157 of the piston portion 152 from the pressure sensor 167 (S703).

[0150] Until the mold protection position is reached, the determination unit 716 determines whether or not the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold T1 (S704). When the determination unit 716 determines that the acquired pressure value exceeds the pressure threshold T1 (S704: Yes), the stop control unit 717 performs stop control on the servo motor 170, and the notification unit 718 notifies the fact that an abnormality has occurred (S705), and the process ends.

[0151] On the other hand, if the determination unit 716 determines that the acquired pressure value does not exceed the pressure threshold T1 (S704: No), the acquisition unit 715 acquires the position of the piston portion 152 in the mold closing direction (S706). The determination unit 716 determines whether the position of the piston portion 152 acquired by the acquisition unit 715 has reached the mold protection position (S707). If it is determined that the position has not reached the mold protection position (S707: No), the process is repeated from S702.

[0152] On the other hand, if the judgment unit 716 determines that the position of the piston portion 152 acquired by the acquisition unit 715 has reached the mold protection position (S707: Yes), the speed control unit 713 controls the servo motor 170 to perform speed control so that the piston portion 152 reaches speed V2 (S708).

[0153] The acquiring unit 715 acquires a pressure value indicating the fluid pressure acting on the oil chamber 157 of the piston portion 152 from the pressure sensor 167 (S709).

[0154] Until the mold protection position is reached, the determination unit 716 determines whether or not the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold T2 (S710). When the determination unit 716 determines that the acquired pressure value exceeds the pressure threshold T2 (S710: Yes), the stop control unit 717 performs stop control on the servo motor 170, and the notification unit 718 notifies the fact that an abnormality has occurred (S711), and the process ends.

[0155] On the other hand, if the determination unit 716 determines that the acquired pressure value does not exceed the pressure threshold T2 (S710: No), the acquisition unit 715 acquires the position of the piston portion 152 in the mold closing direction (S712). The determination unit 716 determines whether the position of the piston portion 152 acquired by the acquisition unit 715 has reached the temperature rise start position (S713). If it is determined that the position has not reached the mold protection position (S713: No), the process is repeated from S708.

[0156] On the other hand, when the determining unit 716 determines that the position of the piston portion 152 acquired by the acquiring unit 715 has reached the temperature increase start position (S713: Yes), the process ends.

[0157] As in the above-described processing procedure, in this embodiment, the speed of the piston portion 152 and the movable platen 120 is controlled from the mold protection position until they reach the pressure increase start position, and whether or not there is an abnormality is determined based on the pressure value detected by the pressure sensor 167. This allows for immediate detection of any abnormality, such as the occurrence of a foreign object being caught, thereby realizing protection of the mold device 800. Furthermore, in this embodiment, the above-described speed control can be performed to suppress variation in the end time of the mold closing process.

[0158] (Variation 1) In the above embodiment, the speed control is performed at the speed V2 from the die protection position to the pressure increase start position. However, the speed control after the die protection position is not limited to one stage, and may be performed in multiple stages. Therefore, in this modification, the speed control is performed in multiple stages after the die protection position.

[0159] Fig. 8 is a diagram showing an example of speed control in the speed control unit 713 according to Modification 1. Fig. 8 shows a speed 1801 of the piston portion 152 and a pressure value 1802 of the fluid pressure acquired by the acquisition unit 715.

[0160] 8, the mold closing process starts at the mold closing start time. The speed control unit 713 controls the piston portion 152 of the hydraulic cylinder 150 to move at a speed V1. Then, when the piston portion 152 reaches the first mold protection position, the speed control unit 713 controls the piston portion 152 to move at a speed V3 (speed V3<speed V1).

[0161] Thereafter, when it reaches the second mold protection position, the speed control unit 713 controls the piston portion 152 to have a speed V4 (speed V4<speed V3), and when it reaches the third mold protection position, the speed control unit 713 controls the piston portion 152 to have a speed V5 (speed V5<speed V4).

[0162] As shown in FIG. 8, in accordance with the speed change caused by the speed control section 713 of the acquisition section 715, the pressure value 1202 detected by the pressure sensor 167 decreases.

[0163] In this modification, the pressure threshold 1803 stored in the threshold storage unit 710 is set to decrease according to the speed. For example, the threshold storage unit 710 stores a pressure threshold T1 from the start of mold closing to arrival at the first mold protection position, stores a pressure threshold T3 from arrival at the first mold protection position to arrival at the second mold protection position, stores a pressure threshold T4 from arrival at the second mold protection position to arrival at the third mold protection position, and stores a pressure threshold T5 from arrival at the third mold protection position to arrival at the temperature rise start position.

[0164] Then, the judgment unit 716 judges whether the pressure value acquired by the acquisition unit 715 exceeds a pressure threshold value (any one of pressure threshold values ​​T1, T3, T4, and T5) stored in the threshold memory unit 710 that is associated with the position where the pressure value was detected.

[0165] 8, at time t4 after arrival at the third mold protection position, the determination unit 716 determines that the pressure value acquired by the acquisition unit 715 has exceeded the pressure threshold T5 stored in the threshold storage unit 710. The process performed when it is determined that the pressure value has exceeded the pressure threshold T5 stored in the threshold storage unit 710 is similar to the above-described embodiment, and therefore the description thereof will be omitted.

[0166] (Variation 2) In the above-described embodiment, an example has been described in which it is determined whether or not an abnormality has occurred based on whether or not the acquired pressure value is higher than the pressure threshold value stored in the threshold value storage unit 710. However, the threshold value used to determine whether or not an abnormality has occurred is not limited to the pre-stored pressure threshold value. Therefore, in Modification 1, an example in which the pressure value is updated based on the actually acquired pressure value will be described.

[0167] The acquisition unit 715 of this modified example adds a predetermined value to the pressure value acquired this time, and associates the value with the position where the pressure value was acquired as the next pressure threshold, and updates the threshold storage unit 710. The position where the pressure value was acquired can be acquired from a linear sensor (not shown) provided in the hydraulic cylinder 150. The predetermined value is a value determined to allow a margin for abnormality determination, and may be any value according to the embodiment. The interval between positions where the pressure value is acquired is set to an interval determined according to the embodiment. This allows the pressure threshold to be updated for each position, taking friction, etc. into consideration, and improves the accuracy of abnormality detection.

[0168] In this modified example, the acquisition unit 715 adds a predetermined value to the pressure value acquired this time (one shot) and sets the value as the next pressure threshold to update the threshold storage unit 710. However, the present invention is not limited to a method of updating the next pressure threshold based on the pressure value of one shot, and the mold closing process may be performed multiple times (e.g., 10 times), and the threshold storage unit 710 may be updated using a moving average of the pressure values ​​acquired by the acquisition unit 715 multiple times as the pressure threshold.

[0169] (Variation 3) The above-described embodiment and modified examples have been described with reference to examples in which the pressure threshold is stored in the threshold storage unit 710. However, the pressure threshold is not limited to being a static parameter, and may be a dynamically generated parameter.

[0170] The determination unit 716 of this modified example holds a mathematical model representing the hydraulic circuit 160 and the hydraulic cylinder 150. The determination unit 716 then acquires the rotation speed of the servo motor 170 controlled by the speed control unit 713, and applies the rotation speed to the mathematical model to calculate an estimate of pressure indicating the fluid pressure generated in the hydraulic cylinder 150.

[0171] Then, the determination unit 716 determines whether or not the difference between the pressure value acquired by the acquisition unit 715 and the estimated pressure value is equal to or greater than a predetermined value. The determination unit 716 determines that an abnormality has occurred when the difference between the pressure value acquired by the acquisition unit 715 and the estimated pressure value is equal to or greater than a predetermined value. In this modified example, an example in which a combination of the estimated pressure value and the predetermined value is used is described, but the same abnormality detection as in the case of using the pressure threshold value shown in the above-mentioned embodiment and modified example can be realized. Furthermore, when the determination is performed using the combination of the estimated pressure value and the predetermined value, in addition to the same effects as in the above-mentioned embodiment, the abnormality determination can be performed with higher accuracy by taking into account the rotation speed of the servo motor.

[0172] In the above-described embodiment and modified example, the piping length can be reduced by forming the hydraulic circuit 160 into a closed circuit using the bidirectional rotary pump 164 and the servo motor 170. This can suppress disturbances, and therefore can improve the accuracy of abnormality detection based on the pressure value detected by the pressure sensor 167 when low-speed control is performed between the mold protection position and the temperature rise start position.

[0173] In the present embodiment and the modified example, an example has been described in which an abnormality is detected based on the pressure value detected by the pressure sensor 167 when low-speed control is performed between the mold protection position and the temperature rise start position in a closed circuit such as the hydraulic circuit 160. However, the method of detecting an abnormality based on the pressure value detected by the pressure sensor 167 while low-speed control is performed between the mold protection position and the temperature rise start position is not limited to the above-mentioned example using a closed circuit, and may be applied to a conventional open hydraulic circuit.

[0174] In the above-described embodiment and modified examples, after the mold protection position, the speed control unit 713 controls the speed of the piston portion 152, thereby making it possible to suppress variation in the arrival time at the temperature rise start position.

[0175] In the above-described embodiment and modified example, when speed control is performed in the mold closing process, the determination unit 716 determines whether or not the pressure value acquired from the pressure sensor 167 exceeds the pressure threshold value, thereby determining whether or not a foreign object has been trapped. This allows for quicker detection of an abnormality than the conventional method of determining whether or not a monitoring time has passed. In addition, since stop control can be performed more quickly than in the past, the mold device 800 can be protected.

[0176] Although the embodiment of the injection molding machine according to the present invention has been described above, the present invention is not limited to the above embodiment. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. Naturally, these also fall within the technical scope of the present invention.

[0177] This application claims priority based on Japanese Patent Application No. 2021-062344, filed on March 31, 2021, the entire contents of which are incorporated by reference into this application. [Explanation of symbols]

[0178] 10 injection molding machine 100 mold clamping device 110 fixed platen 120 movable platen 150 hydraulic cylinder 160 hydraulic circuit 170 servo motor 700 control device 710 threshold value storage unit 711 input processing unit 712 pressure control unit 713 speed control unit 714 switching unit 715 acquisition unit 716 determination unit 717 stop control unit 718 notification unit

Claims

1. a fixed platen on which a fixed mold is mounted; a movable platen on which a movable mold is mounted; a mold clamping device that performs a mold closing step of moving the movable platen by a fluid pressure to bring the movable platen into contact with the fixed platen; a hydraulic cylinder for generating the fluid pressure; A flow path connecting a plurality of oil chambers of the hydraulic cylinder; a bidirectional rotary pump provided in the flow path; A servo motor for controlling the rotation of the double rotary pump; A control unit that controls the mold clamping device, the mold clamping device is capable of switching a flow of oil flowing through the flow path based on a rotation direction of the bidirectional rotary pump, The control unit is a speed control unit that controls a speed of the movable platen in the mold closing process; an acquisition unit that acquires a pressure value indicating the fluid pressure generated by the movement of the movable platen; a determination unit that determines whether the pressure value acquired by the acquisition unit exceeds a predetermined threshold value; a motor control unit that controls an output of the servo motor in response to the pressure value; An injection molding machine comprising:

2. the determining unit performs a determination for each position to which the movable platen is moved based on the predetermined threshold value that is set in advance.

2. The injection molding machine according to claim 1.

3. the determining unit determines whether a time taken for the movable platen to reach a predetermined position exceeds a predetermined time.

2. The injection molding machine according to claim 1.

4. a pressure control unit that controls a pressure on the movable platen in the mold closing process; a switching unit that switches between the pressure control by the pressure control unit and the speed control by the speed control unit when moving the movable platen in the mold closing step, The determination unit, when performing the pressure control by the pressure control unit, determines whether a time taken to reach the predetermined position exceeds the predetermined time, and, when performing the speed control by the speed control unit, determines whether the pressure value acquired by the acquisition unit exceeds the predetermined threshold.

4. The injection molding machine according to claim 3.

5. A storage unit that stores the predetermined threshold value, The predetermined threshold value stored in the storage unit is updated in accordance with the pressure value acquired by the acquisition unit.

2. The injection molding machine according to claim 1.

6. the determination unit calculates an estimate of a pressure generated by movement of the movable platen from a rotation speed of the servo motor that generates the fluid pressure, and determines that the predetermined threshold has been exceeded when a difference between the estimated pressure value and the pressure value acquired by the acquisition unit is equal to or greater than a predetermined value.

2. The injection molding machine according to claim 1.

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