WO2022210921A1

WO2022210921A1 - Injection molding machine

Info

Publication number: WO2022210921A1
Application number: PCT/JP2022/016134
Authority: WO
Inventors: 浩基常深; 眞司寺田; 裕成淺井
Original assignee: 住友重機械工業株式会社
Priority date: 2021-03-31
Filing date: 2022-03-30
Publication date: 2022-10-06
Also published as: CN116583366A; JPWO2022210921A1

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

Injection molding machine

The present invention relates to an injection molding machine.

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 technology has been proposed that uses a hydraulic cylinder as a mold clamping device that moves a movable mold during a mold closing process.

Japanese Patent Application Laid-Open No. 2006-015553

Patent Document 1 describes a technique related to the mold opening process when a hydraulic cylinder is used for the mold clamping device. Specifically, in the mold opening process, the torque is limited, and the time element is monitored to detect whether or not there is an abnormality.

When a hydraulic cylinder is used for the mold clamping device, when controlling the movement of the movable platen in the mold closing process, limit the torque or pressure to a low level and monitor the time element to detect whether there is an abnormality. do. In this control, since the torque or pressure is limited to a low level, the mold closing time until the mold closing process ends varies greatly due to the influence of loads such as friction. For this reason, it is necessary to set the monitoring time (time element) for determining whether there is an abnormality or not to be long with a considerable margin.

For this reason, in the mold closing process, if a foreign object is caught between the fixed mold and the movable mold while it is being determined whether the mold closing process has ended within the monitoring time, the monitoring time is The load continues to be applied to the mold device until the time elapses.

One aspect of the present invention provides a technology that enables rapid detection of abnormalities when controlling the speed of the movable platen in the mold closing process.

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 fluid pressure to move the movable platen to bring the movable platen into contact with the stationary platen. It has a mold clamping device that performs a mold closing process and a control section that controls the mold clamping device. 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 that indicates the fluid pressure generated by the movement of the movable platen, and a pressure value that is acquired by the acquisition unit. and a determination unit that determines whether or not a predetermined threshold is exceeded.

According to one aspect of the present invention, when the speed of the movable platen is controlled, it is possible to quickly detect an abnormality by detecting a change in the fluid pressure caused by the movement of the movable platen.

FIG. 1 is a diagram showing a state of an injection molding machine according to one embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of the injection molding machine according to the embodiment at the time of mold clamping. FIG. 3 is a diagram showing an example of the mold clamping device according to the first embodiment. FIG. 4 is a diagram showing functional blocks of components of the control device according to the first embodiment. FIG. 5 is a diagram exemplifying pressure control in the pressure control unit of the control device according to the first embodiment. FIG. 6 is a diagram showing an example of speed control in the speed control unit according to the first embodiment. FIG. 7 is a flow chart showing processing when speed control is performed in the mold closing process of the control device according to the first embodiment. FIG. 8 is a diagram showing an example of speed control in a speed control unit according to Modification 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same or corresponding configurations are denoted by the same or corresponding reference numerals, and description thereof may be omitted.

FIG. 1 is a diagram showing a state of the injection molding machine according to one embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of the injection molding machine according to the embodiment at the time of mold clamping. In this specification, the X-axis direction, Y-axis direction and Z-axis direction are directions 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 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 Y-axis direction negative side is called the operating side, and the Y-axis direction positive side is called the non-operating side.

As shown in FIGS. 1 and 2, the injection molding machine 10 includes a mold 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, and a It has a moving device 400 that advances and retreats the injection device 300 , 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 the molded product molded by the mold device 800 from the mold device 800 (movable mold 820). The frame 900 includes a mold clamping device frame 910 that supports the mold clamping device 100 and an injection device frame 920 that supports the injection device 300 . The mold clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via leveling adjusters 930 . A control device 700 is arranged in the inner space of the injection device frame 920 . Each component of the injection molding machine 10 will be described below.

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

The mold clamping device 100 performs a mold closing process, a pressurization process, a mold clamping process, a depressurization process, and a mold opening process of the mold device 800 . The mold apparatus 800 includes a fixed mold 810 , a movable mold 820 , and a movable member 830 arranged inside (hollow portion) of the movable mold 820 so as to be able to move back and forth.

The mold clamping device 100 is, for example, a horizontal type, and the mold opening/closing direction is horizontal. The mold clamping device 100 has a stationary platen 110, a movable platen 120, tie bars 140, hydraulic cylinders 150, and the like.

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

The movable platen 120 is arranged movably in the mold opening/closing direction with respect to the mold clamping device frame 910 . A guide 101 for guiding the movable platen 120 is laid on the mold clamping device frame 910 . A movable die 820 is attached to the surface of the movable platen 120 facing the stationary platen 110 . By advancing and retracting the movable platen 120 with respect to the fixed platen 110, the mold closing process, pressure increasing process, mold clamping process, pressure releasing process, and mold opening process of the mold apparatus 800 are performed.

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

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 type to move the movable platen 120 in the mold opening/closing direction. The configuration of the hydraulic cylinder 150 and details of the drive mechanism will be described later (see FIG. 3).

Under the control of the control device 700, the mold clamping device 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a depressurizing process, a mold opening process, and the like.

In the mold closing step, the hydraulic cylinder 150 is driven to advance the hydraulic cylinder 150 (a piston portion 152 described later) at a set movement speed to the mold closing completion position, thereby advancing the movable platen 120 and fixing the movable mold 820. The mold 810 is touched. The position and movement speed of the hydraulic cylinder 150 are detected using, for example, a cylinder pressure sensor or the like. The cylinder pressure sensor detects the telescopic position of hydraulic cylinder 150 and sends a signal indicating the detection result to control device 700 . As a result, the control device 700 performs feedback control regarding the position of the hydraulic cylinder 150 (movable platen 120) (the position of the hydraulic cylinder 150) based on the signal indicating the detection result of the cylinder pressure sensor in the mold clamping process and the mold opening process (to be described later). control).

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 ones can be used.

In the pressurizing step, the hydraulic cylinder 150 is further driven to control the pressure of the hydraulic cylinder 150 to a predetermined pressure (hereinafter referred to as “target mold clamping pressure”). generate power. The pressure of the hydraulic cylinder 150 is detected using, for example, a pressure sensor (cylinder pressure sensor) provided on the hydraulic cylinder 150 . The cylinder pressure sensor detects the pressure of a predetermined oil chamber inside hydraulic cylinder 150 (for example, oil chamber 155 described later) and sends a signal indicating the detection result to control device 700 . As a result, the control device 700 performs feedback control on 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, mold clamping process, and depressurizing process, which will be described later. )It can be performed.

In the mold clamping process, the hydraulic cylinder 150 is driven to maintain the pressure of the hydraulic cylinder 150 at the target mold clamping pressure. In the mold clamping process, the mold clamping force generated in the pressurizing 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 a liquid molding material. A molded product is obtained by solidifying the filled molding material.

The number of cavity spaces 801 may be one or plural. In the latter case, multiple moldings are obtained simultaneously. The insert material may be arranged in part of the cavity space 801 and the other part of the cavity space 801 may be filled with the molding material. A molded product in which the insert material and the molding material are integrated is obtained.

In the depressurization process, the mold clamping force is reduced by driving the hydraulic cylinder 150 to reduce the hydraulic cylinder 150 from the target mold clamping pressure.

In the mold opening process, the hydraulic cylinder 150 is driven to retract the hydraulic cylinder 150 (piston portion 152) from the mold opening start position to the mold opening completion position at a set moving speed, thereby retracting the movable platen 120 and moving the movable mold. 820 is separated from 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.

The setting conditions in the mold closing process, pressure rising process, and mold clamping process are collectively set as a series of setting conditions. For example, the movement speed, position (including the mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position) and pressure (including the target mold clamping pressure) of the hydraulic cylinder 150 in the mold closing process and the pressurizing process , mold clamping force, etc. are collectively set as a series of setting conditions. The mold closing start position, the movement 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 side, and represent the start point and end point of the section in which the movement speed is set. A moving speed is set for each section. The moving speed switching position may be one or plural. The moving speed switching position does not have to be set. Only one or two of the mold clamping position, target mold clamping pressure, and mold clamping force may be set.

The setting conditions in the depressurization process and the mold opening process are set in the same way. For example, the movement speed and position (mold opening start position, movement speed switching position, and mold opening completion position) of the hydraulic cylinder 150 in the depressurization process and the mold opening process are collectively set as a series of setting conditions. The mold opening start position, the movement speed switching position, and the mold opening completion position are arranged in this order from the front side to the rear side, and represent the start point and end point of the section for which the movement speed is set. A moving speed is set for each section. The moving speed switching position may be one or plural. The moving 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. Also, the mold opening completion position and the mold closing start position may be the same position.

It should be noted that instead of the moving speed and position of the hydraulic cylinder 150, the moving speed and position of the movable platen 120 may be set. Also, instead of the position of the hydraulic cylinder 150 (for example, the mold clamping position) and the position of the movable platen 120, a target mold clamping pressure and a mold clamping force may be set.

Although the mold clamping device 100 of this embodiment is a horizontal type in which the mold opening/closing direction is horizontal, it may be a vertical type in which the mold opening/closing direction is a vertical direction.

(ejector device)
In the description of the ejector device, as in the description of the mold clamping device 100, the direction of movement of the movable platen 120 when the mold is closed (for example, 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 (for example, the X direction) is defined as the front. The negative axis direction) will be described as the rear side.

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

The ejector rod is in contact with a movable member 830 arranged to move back and forth inside the movable mold 820, and can move the movable member forward.

The drive mechanism has, for example, an ejector motor and a motion conversion mechanism that converts the rotary motion of the ejector motor into the linear motion of the ejector rod. The motion conversion mechanism includes a threaded shaft and a threaded nut that screws onto the threaded shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

The ejector device performs the ejecting process under the control of the control device 700. In the ejecting process, the ejector device advances the movable member 830 to eject the molded article.

The position and movement speed of the ejector rod are detected using, for example, an ejector motor encoder. The ejector motor encoder detects rotation of the ejector motor and sends a signal indicating the detection result to the control device 700 . Also, the ejector rod position detector for detecting the position of the ejector rod and the ejector rod moving speed detector for detecting the moving speed of the ejector rod are not limited to the ejector motor encoder, and general ones can be used.

(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 moving direction of the screw 330 during filling (for example, the negative direction of the X axis) is defined as the forward direction, and the moving direction of the screw 330 during metering is defined as the forward direction. (For example, the positive direction of the X-axis) will be described as the rear.

The injection device 300 is installed on a slide base 301 , and the slide base 301 is arranged to move forward and backward relative to the injection device frame 920 . The injection device 300 is arranged to move back and forth with respect 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. 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.

The cylinder 310 heats the molding material supplied inside from the supply port 311 . The molding material includes, for example, resin. The molding material is formed into, for example, a pellet shape and supplied to the supply port 311 in a solid state. A supply port 311 is formed in the rear portion of the cylinder 310 . A cooler 312 such as a water-cooled cylinder is provided on the outer circumference of the rear portion of the cylinder 310 . A heater 313 such as a band heater and a temperature detector 314 are provided on the outer periphery of the cylinder 310 ahead of the cooler 312 .

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

The nozzle 320 is provided at the front end of the cylinder 310 and pressed against the mold device 800 . A heater 313 and a temperature detector 314 are provided around the nozzle 320 . The controller 700 controls the heater 313 so that the detected temperature of the nozzle 320 becomes the set temperature.

The screw 330 is arranged in the cylinder 310 so as to be rotatable and advanceable. When the screw 330 is rotated, the molding material is sent forward along the helical groove of the screw 330 . The molding material is gradually melted by the heat from the cylinder 310 while being fed forward. The screw 330 is retracted as liquid molding material is fed forward of the screw 330 and accumulated at the front of the cylinder 310 . After that, 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 in the mold device 800 .

A backflow prevention ring 331 is movably attached to the front of the screw 330 as a backflow prevention valve that prevents backflow of the molding material from the front to the rear of the screw 330 when the screw 330 is pushed forward.

The anti-backflow ring 331 is pushed backward by the pressure of the molding material in front of the screw 330 when the screw 330 is advanced, and is relatively to the screw 330 until it reaches a closed position (see FIG. 2) that blocks the flow path of the molding material. fall back. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

On the other hand, the anti-backflow ring 331 is pushed forward by the pressure of the molding material sent forward along the helical groove of the screw 330 when the screw 330 is rotated, and is in an open position where the flow path of the molding material is opened. (see FIG. 1) relative to the screw 330. Thereby, the molding material is sent forward of the screw 330 .

The anti-backflow 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 .

It should be noted that the injection device 300 may have a drive source that advances and retracts the backflow prevention ring 331 with respect to the screw 330 between the open position and the closed position.

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.

The injection motor 350 moves the screw 330 forward and backward. Between the injection motor 350 and the screw 330, a motion conversion mechanism or the like that converts the rotary motion of the injection motor 350 into the linear motion of the screw 330 is provided. The motion conversion mechanism has, for example, a screw shaft and a screw nut that screws onto the screw shaft. Balls, rollers, or the like may be provided between the screw shaft and the screw nut. The drive source for advancing and retreating the screw 330 is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder.

A 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 in the force transmission path between the injection motor 350 and the screw 330 and detects the force acting on the load detector 360 .

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 for controlling and monitoring the pressure that the screw 330 receives from the molding material, the back pressure against the screw 330, the pressure that the screw 330 acts on the molding material, and the like.

Note that the pressure detector that detects the pressure of the molding material is not limited to the load detector 360, and a general one can be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. A nozzle pressure sensor is installed at the nozzle 320 . The mold internal pressure sensor is installed inside the mold apparatus 800 .

Under the control of the control device 700, the injection device 300 performs a weighing process, a filling process, a holding pressure process, and the like. The filling process and the holding pressure process may collectively be called an injection process.

In the weighing process, the weighing motor 340 is driven to rotate the screw 330 at a set rotation speed, and the molding material is fed forward along the helical groove of the screw 330. Along with this, the molding material is gradually melted. The screw 330 is retracted as liquid molding material is fed forward of the screw 330 and accumulated at the front of the cylinder 310 . The rotation speed of the screw 330 is detected using a metering motor encoder 341, for example. Weighing motor encoder 341 detects the rotation of weighing motor 340 and sends a signal indicating the detection result to control device 700 . Moreover, the screw rotation speed detector for detecting the rotation speed of the screw 330 is not limited to the metering motor encoder 341, and a general one can be used.

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

The position and rotational speed of the screw 330 in the weighing process are collectively set as a series of setting conditions. For example, a weighing start position, rotation speed switching position, and weighing completion position are set. These positions are arranged in this order from the front side to the rear side, and represent the start point and end point of the section in which the rotational speed is set. A rotation speed is set for each section. The rotational speed switching position may be one or plural. The rotation speed switching position does not have to be set. Also, the back pressure is set for each section.

In the filling process, the injection motor 350 is driven to advance the screw 330 at a set movement 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 using an injection motor encoder 351, for example. The injection motor encoder 351 detects 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, switching from the filling process to the holding pressure process (so-called V/P switching) is performed. The position at which V/P switching takes place is also called the V/P switching position. The set moving speed of the screw 330 may be changed according to the position of the screw 330, time, and the like.

The position and movement speed of the screw 330 in the filling process are collectively set as a series of setting conditions. For example, a filling start position (also called an “injection start position”), a moving 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 side, and represent the start point and end point of the section for which the movement speed is set. A moving speed is set for each section. The moving speed switching position may be one or plural. The moving speed switching position does not have to be set.

The upper limit value of 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 screw 330 is detected by load detector 360 . When the detected value of the load detector 360 is equal to or less 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 moves at a slower moving speed than the set moving speed so that the detected value of the load detector 360 becomes equal to or less than the set pressure for the purpose of mold protection. to move forward.

It should be noted that 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 slowly advanced or slowly retracted. Moreover, the screw position detector for detecting the position of the screw 330 and the screw moving speed detector for detecting the moving speed of the screw 330 are not limited to the injection motor encoder 351, and general ones can be used.

In the holding pressure process, 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 the set pressure. The remaining molding material is pushed toward the mold device 800 . A shortage of molding material due to cooling shrinkage in the mold apparatus 800 can be replenished. The holding pressure is detected using the load detector 360, for example. Load detector 360 sends a signal indicating the detection result to control device 700 . The set value of the holding pressure may be changed according to the elapsed time from the start of the holding pressure process. A plurality of holding pressures and holding times for holding the holding pressure in the holding pressure step may be set respectively, and may be collectively set as a series of setting conditions.

In the holding pressure process, the molding material in the cavity space 801 inside the mold device 800 is gradually cooled, and when the holding pressure process is completed, the entrance of the cavity space 801 is closed with 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 holding pressure process, the cooling process is started. In the cooling process, the molding material inside the cavity space 801 is solidified. A metering step may be performed during the cooling step for the purpose of shortening the molding cycle time.

Although the injection device 300 of the present embodiment is of the in-line screw method, it may be of the pre-plastic method or the like. A pre-plastic injection apparatus supplies molding material melted in a plasticizing cylinder to an injection cylinder, and injects the molding material from the injection cylinder into a mold apparatus. Inside the plasticizing cylinder, a screw is arranged to be rotatable and non-retractable, or a screw is arranged to be rotatable and reciprocal. On the other hand, a plunger is arranged in the injection cylinder so that it can move back and forth.

Further, the injection device 300 of the present 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. The mold clamping device combined with the vertical injection device 300 may be either vertical or horizontal. Similarly, the mold clamping device combined with the horizontal injection device 300 may be horizontal or vertical.

Thus, in this embodiment, the injection device 300 is electrically driven by electric actuators such as the metering motor 340 and the injection motor 350 . As a result, the injection device 300 can be relatively more responsive to the control command from the control device 700 than when it is hydraulically driven. Therefore, the injection molding machine 10 can achieve relatively excellent controllability of the injection device 300 .

(moving device)
In the description of the moving device 400, as in the description of the injection device 300, the moving direction of the screw 330 during filling (for example, the negative direction of the X-axis) is defined as forward, and the moving direction of the screw 330 during weighing (eg, the positive direction of the X-axis). is described as backward.

The moving device 400 advances and retreats the injection device 300 with respect to the mold device 800 . Further, the moving device 400 presses the nozzle 320 against the mold device 800 to generate 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.

The hydraulic pump 410 has a first port 411 and a second port 412 . Hydraulic pump 410 is a pump that can rotate in both directions, and by switching the rotation direction of motor 420, hydraulic fluid (for example, oil) is sucked from one of first port 411 and second port 412 and discharged from the other. to generate hydraulic pressure. In addition, the hydraulic pump 410 can also suck the hydraulic fluid from the tank and discharge the hydraulic fluid from either the first port 411 or the second port 412 .

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

The hydraulic cylinder 430 has a cylinder body 431 , a piston 432 and a piston rod 433 . The cylinder body 431 is fixed with respect to the injection device 300 . The piston 432 partitions 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. Piston rod 433 is fixed relative to stationary platen 110 .

The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via the first flow path 401 . The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 through the first flow path 401, thereby pushing the injection device 300 forward. The injection device 300 is advanced and the nozzle 320 is pressed against the stationary mold 810 . The front chamber 435 functions as a pressure chamber that generates nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410 .

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 through the second flow path 402, thereby pushing the injection device 300 rearward. The injection device 300 is retracted and the nozzle 320 is separated from the stationary mold 810 .

Although the moving device 400 includes the hydraulic cylinder 430 in this embodiment, 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 rotary motion of the electric motor to the linear motion of the injection device 300 may be used.

(Control device)
The control device 700 is composed of, for example, 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 FIGS. The control device 700 performs various controls by causing the CPU 701 to execute programs stored in the storage medium 702 . The control device 700 also receives signals from the outside through an input interface 703 and transmits signals to the outside through an output interface 704 .

The control device 700 repeatedly performs a weighing process, a mold closing process, a pressurizing process, a mold clamping process, a filling process, a holding pressure process, a cooling process, a depressurizing process, a mold opening process, and an ejecting process, thereby producing a molded product. Repeat production. A series of operations for obtaining a molded product, for example, the operation from the start of the weighing process to the start of the next weighing process, is also called "shot" or "molding cycle". The time required for one shot is also called "molding cycle time" or "cycle time".

A single molding cycle has, for example, a weighing process, a mold closing process, a pressure increasing process, a mold clamping process, a filling process, a holding pressure process, a cooling process, a depressurizing process, a mold opening process, and an ejecting process in this order. The order here is the order of the start of each step. The filling process, holding pressure process, and cooling process are performed during the clamping process. The start of the clamping process may coincide with the start of the filling process. The end of the depressurization process coincides with the start of the mold opening process.

In addition, multiple processes may be performed at the same time for the purpose of shortening the molding cycle time. For example, the metering step may occur during the cooling step of the previous molding cycle and may occur during the clamping step. In this case, the mold closing process may be performed at the beginning of the molding cycle. The filling process may also be initiated during the mold closing process. Also, the ejecting process may be initiated during the mold opening process. If an on-off valve for opening and closing the flow path of the nozzle 320 is provided, the mold opening process may be initiated during the metering process. This is because the molding material does not leak from the nozzle 320 as long as the on-off valve closes the flow path of the nozzle 320 even if the mold opening process is started during the metering process.

One molding cycle includes processes other than the weighing process, mold closing process, pressurizing process, mold clamping process, filling process, holding pressure process, cooling process, depressurizing process, mold opening process, and ejecting process. may

For example, after the pressure holding process is completed, a pre-measuring suck-back process may be performed in which the screw 330 is retracted to a preset measuring start position before starting the measuring process. It is possible to reduce the pressure of the molding material accumulated in front of the screw 330 before the start of the metering process, and to prevent the screw 330 from abrupt retraction at the start of the metering process.

Also, after the weighing process is completed and before the filling process starts, a post-weighing suck-back process may be performed in which the screw 330 is retracted to a preset filling start position (also referred to as an "injection start position"). The pressure of the molding material accumulated in front of the screw 330 before the start of the filling process can be reduced, and leakage of the molding material from the nozzle 320 before the start of the filling process can be prevented.

The control device 700 is connected to an operation device 750 that receives user input operations and a display device 760 that displays screens. The operation device 750 and the display device 760 may be configured by, for example, a touch panel 770 and integrated. A touch panel 770 as a display device 760 displays a screen under the control of the control device 700 . Information such as the settings of the injection molding machine 10 and the current state of the injection molding machine 10 may be displayed on the screen of the touch panel 770 . Further, on the screen of the touch panel 770, for example, an operation unit such as a button for receiving an input operation by the user or an input field may be displayed. A 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 . As a result, for example, the user can operate the operation unit provided on the screen while confirming the information displayed on the screen to set the injection molding machine 10 (including input of set values). can. Further, the user can operate the operation unit provided on the screen to cause the injection molding machine 10 to operate corresponding to the operation unit. The operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the mold clamping device 100, the ejector device 200, the injection device 300, the moving device 400, and the like. Also, the operation of the injection molding machine 10 may be switching of screens displayed on the touch panel 770 as the display device 760 .

Although the operating device 750 and the display device 760 of the present embodiment have been described as being integrated as the touch panel 770, they may be provided independently. Also, a plurality of operating devices 750 may be provided. The operating device 750 and the display device 760 are arranged on the operating side (Y-axis negative direction) of the mold clamping device 100 (more specifically, the fixed platen 110).

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

FIG. 3 is a diagram showing an example of the mold clamping device 100 according to this embodiment. Specifically, FIG. 3 is a diagram showing the operating state of the mold clamping device 100 in the mold closing process. In addition, drawing of the mold device 800 is omitted in FIG.

As shown in FIG. 3, the mold clamping device 100 includes a stationary platen 110, a movable platen 120, tie bars 140, a hydraulic cylinder 150, a hydraulic circuit 160, and a servomotor 170.

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

The cylinder body portion 151 is a fixed portion of the hydraulic cylinder 150 . Cylinder main body 151 is connected to the other end of tie bar 140 , one end of which is connected to stationary platen 110 . As a result, the cylinder main body 151 is fixed at a constant distance (interval L) from the fixed platen 110 . The cylinder main body 151 is provided with a hollow portion whose front end (the end in the negative direction of the X axis) is open.

One of the cylinder main body 151 and the stationary platen 110 that are connected via tie bars 140 is fixed to the mold clamping device frame 910 and the other is movably mounted on the mold clamping device frame 910 . Thereby, the elongation of the tie bar 140 due to the generation of the mold clamping force can be allowed.

One end of the piston portion 152 is inserted into the interior (hollow portion) of the cylinder body portion 151 and the other end is fixed to the movable platen 120 . As a result, the piston portion 152 can move in the front-rear direction (X direction) by the action of the working oil supplied to and discharged from the cylinder body portion 151, and as a result, the movable platen 120 fixed to one end of the piston portion 152 moves back and forth. It can be moved in the direction (X direction). Further, the piston portion 152 is provided with a hollow portion that opens to the inside of the cylinder body portion 151 .

One end of the rod portion 153 is fixed to the closed end portion of the hollow portion of the cylinder main body portion 151 (that is, the end portion in the negative direction of the X axis), and the other end is inserted into the hollow portion of the piston portion 152 . Accordingly, the rod portion 153 can move the piston portion 152 forward (positive direction of the X-axis) by the action of hydraulic oil supplied to a hollow portion (an oil chamber 157 described later) of the piston portion 152 . Further, the rod portion 153 is provided with a hole extending in the axial direction from the other end side that is inserted into the hollow portion of the piston portion 152 .

The cylinder closing portion 154 closes the open end of the cylinder body portion 151 . The cylinder closing portion 154 is provided with a through hole through which the piston portion 152 can advance and retreat.

Also, oil chambers 155 to 157 are provided inside the hydraulic cylinder 150 .

The oil chamber 155 is defined by the inner wall of the cylinder body 151 and the tip (one end) of the piston 152 at the closed end (the end in the negative direction of the X axis) of the hollow portion of the cylinder body 151 . be provided. As a result, the piston portion 152 can exert a mold clamping force on 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.

This embodiment relates to the mold closing process, and the hydraulic circuit for supplying and discharging working oil to and from the oil chamber 155 for applying the mold clamping force may be the same as the conventional hydraulic circuit, and the description is omitted. do.

The oil chamber 156 is partitioned by the inner wall of the cylinder body 151, the inner wall of the cylinder closing portion 154, and the intermediate portion of the piston portion 152 at the open end of the cylinder body 151 (the end in the positive direction of the X axis). provided in As a result, the piston portion 152 can move backward (that is, move in the negative direction of the X-axis) by the action of hydraulic oil supplied to the oil chamber 156 . The oil chamber 156 is provided with a port 156P for supplying and discharging hydraulic oil.

The oil chamber 157 is provided so as to be partitioned by the inner wall of the hollow portion of the piston portion 152 and the tip portion of the rod portion 153 . As a result, the piston portion 152 can move forward (that is, move in the positive direction of the X-axis) by the action of hydraulic oil supplied to the oil chamber 157 . The oil chamber 157 communicates with the hole of the rod portion 153 , and a port 157</b>P for supplying and discharging working oil to and from the oil chamber 157 is provided at the tip of the hole of the rod portion 153 .

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

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.

The oil passage OL2 connects between the supply/discharge port 157P of the oil chamber 157 and the double rotary pump 164. Also, the oil passage OL2 is connected to each of the mold closing side relief valve 161, the regulating valve 163, and the check valve 165. As shown in FIG. A pressure sensor 167 is provided in the vicinity of the supply/discharge port 157P of the oil chamber 157 of the oil passage OL2.

The oil passage OL3 connects between the supply/discharge port 156P of the oil chamber 156 and the double rotary pump 164. Also, 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. As shown in FIG.

Both rotary pumps 164 are provided on flow paths (oil path OL2 and oil path OL3) that connect between a plurality of oil chambers (oil chamber 157 and oil chamber 156) of hydraulic cylinder 150 that generates fluid pressure. there is The dual rotary pump 164 according to this embodiment is driven by a servomotor 170 to adjust the flow direction and flow rate of the working oil flowing between the oil passages OL2 and OL3. In this manner, both rotary pumps 164 can discharge working oil to both oil passage OL2 and oil passage OL3 based on the drive by servomotor 170 .

For example, both rotary pumps 164 are driven by the servomotor 170 to discharge the working oil supplied from the oil passage OL2 to the oil passage OL3. This realizes a flow path through which working oil flows from the supply/discharge port 157P of the oil chamber 157 to the supply/discharge port 156P of the oil chamber 156 through the oil passages OL2 and OL3 in this order. As a result, the piston part 152 retreats (that is, moves in the X-axis negative direction), so that the mold opening step of moving the movable mold 820 in the mold opening direction can be realized.

As another example, both rotary pumps 164 discharge the working oil supplied from oil passage OL3 to oil passage OL2 based on the drive by servomotor 170. This realizes a flow path through which working oil flows from the supply/discharge port 156P of the oil chamber 156 to the supply/discharge port 157P of the oil chamber 157 through the oil passages OL3 and OL2 in this order. As a result, the piston part 152 advances (that is, moves in the positive direction of the X-axis), so that the mold closing process of moving the movable mold 820 in the mold closing direction can be realized.

The mold opening side relief valve 162 is a relief valve provided in the oil passage OL3, and is a mechanical valve that switches between a communication state and a cutoff 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 becomes equal to or higher than a predetermined pressure, the mold opening side relief valve 162 is put into a communication state, and the working oil flowing in the oil passage OL3 is discharged to the tank 168 via the oil passage OL1. discharge up to

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 communication state and a cutoff 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 exceeds a predetermined pressure, the mold closing side relief valve 161 is put into a communication state, and the working oil flowing in the oil passage OL2 is discharged to the tank 168 via the oil passage OL1. discharge up to

The check valve 165 is a valve that allows the hydraulic oil to flow in one direction from the oil passage OL1 to the oil passage OL2 and prevents reverse flow. The hydraulic circuit 160 of this embodiment is provided with a check valve 165 so that working oil is supplied from the tank 168 to the oil passage OL2.

The check valve 166 is a valve that allows the hydraulic oil to flow in one direction from the oil passage OL1 to the oil passage OL3 and prevents reverse flow. The hydraulic circuit 160 of the present embodiment is provided with a check valve 166 so that working oil is supplied from the tank 168 to the oil passage OL3.

The tank 168 stores hydraulic oil. Also, the tank 168 is 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. Thereby, 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. Also, the tank 168 supplies the stored working oil through the oil passage OL1 from the check valve 165 to the oil passage OL2 or from the check valve 166 to the oil passage OL3.

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

Since the pressure sensor 167 is provided on the oil passage OL2 and in the vicinity of the supply/discharge port 157P of the oil chamber 157 of the hydraulic cylinder 150, the pressure applied to the oil chamber 157 of the hydraulic cylinder 150 is detected. .

That is, in conventional hydraulic circuits for controlling hydraulic cylinders, a variable pump capable of discharging working oil in only one direction was often used in place of the bidirectional rotary pump 164 capable of discharging working oil in both directions. . When such a variable pump is used, an electromagnetic switching valve (an example of a direction switching valve) for switching the oil chamber for supplying working oil is provided. By switching the oil chamber to which the working oil is supplied with this electromagnetic switching valve, the mold opening process and the mold closing process are realized.

　Conventional electromagnetic switching valves were often installed near the hydraulic cylinder. When a pressure sensor is provided in such a conventional hydraulic circuit, various parts constituting an electromagnetic switching valve are interposed between the hydraulic sensor and the hydraulic cylinder. Therefore, in the conventional hydraulic circuit, it was difficult to detect the pressure applied to the oil chamber of the hydraulic cylinder with the pressure sensor.

On the other hand, in the hydraulic circuit 160 of the present embodiment, the oil chamber to which the working oil is supplied can be switched by switching the discharge direction of the working oil of the two rotary pumps 164 according to the rotating direction of the servomotor 170 . Such a configuration eliminates the need 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 the present embodiment can reduce the number of constituent parts compared to the conventional hydraulic circuit, the pipe length of the hydraulic circuit 160 can be shortened compared to the conventional hydraulic circuit. Since the piping length can be shortened, the hydraulic circuit 160 can be formed of steel pipes. Thereby, the pressure change due to disturbance can be reduced.

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 the oil passage OL2A (part of the oil passage OL2). Since pressure changes due to disturbances can also be reduced in the hydraulic circuit 160, the pressure sensor 167 can detect the pressure applied to the oil chamber 157 of the hydraulic cylinder 150 with high accuracy.

Compared to conventional hydraulic circuits, the hydraulic circuit 160 of this embodiment does not have an electromagnetic contactor or the like and has a short pipe length, so the amount of heat generated is small and the oil temperature is less likely to rise. Therefore, the amount of hot water used in the hydraulic circuit 160 can be reduced. As a result, the capacity of the tank 168 can be reduced, so that the mold clamping device 100 can be made compact.

The servomotor 170 operates under the control of the control device 700 and controls the rotation of both rotary pumps 164 . Thereby, the control device 700 can control the operation of both rotary pumps 164 by controlling the servo motor 170 .

The control device 700 controls the flow of hydraulic oil in the hydraulic circuit 160 by controlling both rotary pumps 164 (servo motors 170), and realizes the mold closing process and the mold opening process by the mold clamping device 100. Further, the control device 700 also realizes a pressurizing process, a mold clamping process, and a depressurizing process by controlling the hydraulic circuit 160, but the description thereof will be omitted.

FIG. 4 is a diagram showing functional blocks of the components of the control device 700 according to the first embodiment. Each functional block illustrated in FIG. 4 is conceptual and does not necessarily need to be physically configured as illustrated. All or part of each functional block can be functionally or physically distributed and integrated in arbitrary units. Each processing function performed by each functional block is implemented by a program executed by the CPU 701, in whole or in part. Alternatively, each functional block may be implemented as hardware by 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, and 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 .

The threshold storage unit 710 stores the pressure threshold used when speed control is performed in the mold closing process.

The input processing unit 711 inputs and processes user operations from the operation device 750 via the input interface 703 . For example, the input processing unit 711 performs input processing for selecting either pressure control or speed control from the user when performing the mold closing process.

When moving the movable platen in the mold closing process, the switching unit 714 of the present embodiment controls the movable platen 120 and the piston unit 152 by pressure control by the pressure control unit 712 based on the selection operation input processed by the input processing unit 711. Control to move and control to move the movable platen 120 and the piston part 152 by speed control by the speed control unit 713 are switched. The pressure control section 712 and the speed control section 713 will be described later.

The pressure control unit 712 performs pressure control using the hydraulic cylinder 150 in the mold closing process. FIG. 5 is a diagram showing an example of pressure control in the pressure control section 712. As shown in FIG. FIG. 5 shows velocity 1502 and pressure 1501 of piston portion 152 .

In the example shown in FIG. 5, the mold closing process is started at the mold closing start time. The pressure control section 712 controls the movable platen 120 together with the piston section 152 of the hydraulic cylinder 150 so that it reaches the speed V1. After the piston portion 152 reaches the mold protection position, the pressure control portion 712 switches the control performed on the piston portion 152 from speed control to pressure control. Pressure control, in pressure control, is to control so that the pressure does not exceed 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 reaching the mold protection position.

The determination unit 716 determines whether or not the time required for the movable platen 120 to reach the pressure increase start position (an example of the predetermined position) has exceeded the monitoring time (an example of the predetermined time). In the example shown in FIG. 5, at time t1, it is assumed that an abnormality such as a foreign object being caught in mold device 800 occurs. As a result, the speed 1502 of the movable platen 120 is reduced together with the piston portion 152 .

The determination unit 716 determines that an abnormality has occurred when the monitoring time t2 has passed. Although the determination is not performed until the monitoring time t2 has elapsed after the foreign matter is caught in this way, the effect that the foreign matter has little influence on the mold apparatus 800 can be obtained because of the low pressure control.

The stop control unit 717 stops the servomotor 170 when the determining unit 716 determines that the time taken to reach the boost start position (an example of the predetermined position) exceeds the monitoring time (an example of the predetermined time). control to allow

The notification unit 718 notifies that an abnormality has occurred when the determination unit 716 determines that the time taken to reach the boost start position (an example of the predetermined position) exceeds the monitoring time (an example of the predetermined time). , a worker using the injection molding machine 10, a monitoring center, or the like.

By the way, when the pressure applied to the piston part 152 is lowered like the low pressure control by the pressure control part 712, it becomes susceptible to the influence of friction and the like, so the completion time of the mold closing process varies. Therefore, in the low pressure control by the pressure control unit 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 an abnormality.

Therefore, the control device 700 according to the present embodiment enables speed control by the speed control unit 713 instead of pressure control by the pressure control unit 712 .

Returning to FIG. 4, the speed control unit 713 of this embodiment controls the speed of the movable platen 120 fixed to the hydraulic cylinder 150 together with the hydraulic cylinder 150 that moves in the mold closing process.

Specifically, the speed control unit 713 of this embodiment controls the speed so that the piston unit 152 and the movable platen 120 are at the speed V1 from the start of the mold closing process to the arrival at the mold protection position. After the piston portion 152 and the movable platen 120 arrive at the mold protection position, the speed control portion 713 controls the piston portion 152 and the movable platen 120 at the speed V2 (speed V2<speed V1) until the pressure rise start position is reached. Control the speed so that When the speed control unit 713 performs speed control, the pressure value detected by the pressure sensor 167 is used to determine whether there is an abnormality. In other words, since the present embodiment includes the above-described hydraulic circuit 160, the pressure value can be detected with high accuracy, so it is possible to determine whether or not the pressure value is abnormal.

In addition, feedback control may be incorporated into the speed control unit 713 to control the speeds of the piston unit 152 and the movable platen 120 so as not to vary.

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

Furthermore, the acquisition unit 715 acquires the position of the piston part 152 in the mold closing direction from a linear sensor (not shown) provided in the hydraulic cylinder 150 . This makes it possible to recognize whether the piston portion 152 has reached the mold protection position or the temperature increase start position. The mold protection position is a position where 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) at which the mold closing process is completed.

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 .

FIG. 6 is a diagram showing an example of speed control in the speed control section 713 according to this embodiment. FIG. 6 shows the velocity 1601 of the piston part 152 and the pressure value 1602 of the fluid pressure acquired by the acquisition part 715 .

In the example shown in FIG. 6, the mold closing process is started 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 so that it reaches the speed V1. After the piston portion 152 reaches the mold protecting position, the speed control portion 713 controls the moving platen 120 together with the piston portion 152 to 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.

The acquisition unit 715 acquires the pressure value P2 that has decreased from the pressure value P1 according to the speed change by the speed control unit 713 .

The threshold storage unit 710 stores a pressure threshold value T1 for speed control by the speed control unit 713 and a pressure threshold value T2 for reaching the mold protection position and the pressure increase start position from the mold protection position. is doing. Thus, the threshold storage unit 710 stores predetermined pressure thresholds according to the positions to which the movable platen 120 and the piston unit 152 have moved.

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 of this embodiment performs determination based on a predetermined pressure threshold for each position to which the movable platen 120 and the piston unit 152 have moved. Specifically, the determining unit 716 determines whether or not the acquired pressure value exceeds the pressure threshold value T1 until reaching the mold protection position, , determines whether the acquired threshold exceeds the pressure threshold T2. Also, in the case of speed control, as in pressure control, determination unit 716 determines whether or not an abnormality has occurred according to whether or not the time until reaching the pressure increase start position exceeds the monitoring time. good too.

In the example shown in FIG. 6, 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 storage unit 710 at time t3. As described above, in the speed control of the present embodiment, it is possible to immediately perform an abnormality determination when a foreign object is caught.

The stop control unit 717 performs control to stop the servomotor 170 when it is determined that the pressure value acquired by the determination unit 716 exceeds the pressure threshold. In this embodiment, the case of performing control to stop the servomotor 170 will be described, but the control is not limited to the control to stop, and for example, control to reversely rotate the servomotor 170 is also conceivable.

When the determination unit 716 determines that the pressure value obtained by the determination unit 716 exceeds the pressure threshold, the notification unit 718 notifies the operator using the injection molding machine 10, the monitoring center, etc. that an abnormality has occurred. .

FIG. 7 is a flow chart showing processing when speed control is performed in the mold closing process of the control device 700 according to this embodiment. As for the pressure control, the same method as the conventional method may be used, and the explanation is omitted.

First, the control device 700 determines whether or not the mold closing process is started by speed control (S701). If it is determined that the mold closing process by speed control is not started (S701: No), the process ends.

When the control device 700 determines that the mold closing process is started by speed control (S701: Yes), the speed control section 713 controls the servo motor 170 to control the speed of the piston section 152 to the speed V1. (S702).

The acquisition unit 715 acquires from the pressure sensor 167 the pressure value indicating the fluid pressure applied to the oil chamber 157 of the piston portion 152 (S703).

The determination unit 716 determines whether the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold value T1 until the die protection position is reached (S704). When the determination unit 716 determines that the acquired pressure value exceeds the pressure threshold value T1 (S704: Yes), the stop control unit 717 controls the servomotor 170 to stop, and the notification unit 718 has occurred (S705), and the process ends.

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

On the other hand, when the determination unit 716 determines that the position of the piston part 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 , the speed control is performed so that the piston portion 152 reaches the speed V2 (S708).

The acquisition unit 715 acquires from the pressure sensor 167 the pressure value indicating the fluid pressure applied to the oil chamber 157 of the piston portion 152 (S709).

The determination unit 716 determines whether the pressure value acquired by the acquisition unit 715 exceeds the pressure threshold value T2 until the die protection position is reached (S710). When the determination unit 716 determines that the acquired pressure value exceeds the pressure threshold value T2 (S710: Yes), the stop control unit 717 controls the servomotor 170 to stop, and the notification unit 718 detects an abnormality. is notified (S711), and the process ends.

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

On the other hand, when the determination unit 716 determines that the position of the piston part 152 acquired by the acquisition unit 715 has reached the temperature increase start position (S713: Yes), the process ends.

As in the processing procedure described above, in this embodiment, the speed of the piston portion 152 and the movable platen 120 is controlled from the mold protection position to the pressure increase start position, and the pressure value detected by the pressure sensor 167 is Based on the above, it is determined whether or not there is an abnormality. As a result, it is possible to immediately detect when an abnormality such as a foreign object is caught, so that the mold apparatus 800 can be protected. Further, in the present embodiment, by performing the speed control described above, it is possible to suppress variations in the end time of the mold closing process.

(Modification 1)
In the embodiment described above, the case where speed control is performed at the speed V2 from the mold protection position to the pressure rising start position has been described. However, the speed control after the die protection position is not limited to one step, and may be controlled in multiple steps. Therefore, in this modified example, a case in which speed control is performed in multiple steps after the mold protection position will be described.

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

In the example shown in FIG. 8, the mold closing process is started at the mold closing start time. The speed control unit 713 controls the piston portion 152 of the hydraulic cylinder 150 to reach the speed V1. Then, when the piston portion 152 reaches the first mold protection position, the speed control portion 713 controls the piston portion 152 to have a speed V3 (speed V3<speed V1).

After that, when reaching the second mold protection position, the speed control unit 713 controls the piston part 152 to have a speed V4 (speed V4<speed V3), and when reaching the third mold protection position, The speed control portion 713 controls the piston portion 152 to have a speed V5 (speed V5<speed V4).

As shown in FIG. 8, the acquisition unit 715 decreases the pressure value 1202 detected by the pressure sensor 167 according to the speed change by the speed control unit 713 .

In this modified example, 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, and stores a pressure threshold T3 from arrival at the first mold protection position to arrival at the second mold protection position. Then, a pressure threshold T4 from arrival at the second mold protection position to arrival at the third mold protection position is stored, and a pressure threshold T5 from arrival at the third mold protection position to arrival at the temperature rise start position is stored.

Then, the determination unit 716 determines that the pressure value acquired by the acquisition unit 715 is a pressure threshold (pressure thresholds T1, T3, Either one of T4 and T5) is exceeded.

In the example shown in FIG. 8, at time t4 after arriving at the third mold protection position, the determination unit 716 determines that the pressure value acquired by the acquisition unit 715 is the pressure threshold value T5 stored in the threshold storage unit 710. determined to have exceeded The process when it is determined that the pressure value exceeds the pressure threshold value T5 stored in the threshold storage unit 710 is the same as in the above-described embodiment, and the description thereof is omitted.

(Modification 2)
In the above-described embodiment, an example of determining 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 storage unit 710 has been described. However, the threshold used to determine whether an abnormality has occurred is not limited to the pre-stored pressure threshold. Therefore, in Modification 1, an example of updating based on an actually acquired pressure value will be described.

The acquisition unit 715 of this modified example updates the threshold storage unit 710 by associating a value obtained by adding a predetermined value to the pressure value acquired this time as the next pressure threshold value with the position where the pressure value was acquired. Note that the position at which the pressure value is acquired can be acquired from a linear sensor (not shown) provided in the hydraulic cylinder 150 . It should be noted that the predetermined value is a value that is determined in order to provide a margin in determining abnormality, and may be an arbitrary value according to the mode of implementation. The interval between the positions where the pressure values are acquired is set according to the embodiment. As a result, the pressure threshold value can be updated in consideration of friction and the like for each position, and the abnormality detection accuracy can be improved.

In this modified example, an example has been described in which the acquisition unit 715 updates the threshold storage unit 710 with a value obtained by adding a predetermined value to the pressure value acquired this time (one shot) as the next pressure threshold. However, the method is not limited to the method of updating the next pressure threshold value based on the pressure value of one shot. The threshold storage unit 710 may be updated using the moving average of the values as the pressure threshold.

(Modification 3)
In the embodiments and modifications described above, the example in which the pressure threshold is stored in the threshold storage unit 710 has been described. However, the pressure threshold is not limited to static parameters, but may be dynamically generated parameters.

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

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 using a combination of an estimated pressure value and a predetermined value will be described, but the same abnormality detection as in the case of using the pressure threshold shown in the above-described embodiment and modified example can be realized. Furthermore, when the determination is made using the combination of the estimated value of the pressure and the predetermined value, in addition to the same effect as the above-described embodiment, the rotational speed of the servomotor is taken into consideration, and the abnormality determination can be made with higher accuracy. It can be performed.

In the embodiment and modification described above, the use of both the rotary pump 164 and the servomotor 170 makes the hydraulic circuit 160 a closed circuit, thereby reducing the pipe length. Since this can suppress disturbance, it is possible to 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.

In the present embodiment and the modified example, 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, an abnormality is detected based on the pressure value detected by the pressure sensor 167. An example of doing so has been described. However, the method of detecting an abnormality based on the pressure value detected by the pressure sensor 167 while performing low-speed control between the mold protection position and the temperature rise start position is limited to the example using the closed circuit described above. It may be applied to a conventional open circuit hydraulic circuit instead of a conventional one.

In the above-described embodiment and modification, the speed control unit 713 controls the speed of the piston unit 152 after the mold protection position, thereby suppressing variations in arrival time at the temperature rise start position. can.

In the above-described embodiment and modification, when speed control is performed in the mold closing process, the determination unit 716 determines whether the pressure value obtained from the pressure sensor 167 exceeds the pressure threshold. An abnormality such as a foreign object being caught is determined. As a result, it is possible to realize quick abnormality detection as compared with the conventional determination of whether or not the monitoring time has passed. In addition, since stop control can be performed more quickly than in the conventional art, the protection of the mold apparatus 800 can be realized.

Although the embodiments of the injection molding machine according to the present invention have been described above, the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally belong to the technical scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2021-062344 filed on March 31, 2021, and the entire contents of this Japanese Patent Application are incorporated herein by reference.

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 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

a stationary platen to which the stationary mold is attached;
a movable platen to which the movable mold is attached;
a mold clamping device that performs a mold closing step of moving the movable platen by fluid pressure and bringing the movable platen into contact with the stationary platen;
a control unit that controls the mold clamping device,
The control unit
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 movement of the movable platen;
a determination unit that determines whether the pressure value acquired by the acquisition unit exceeds a predetermined threshold;
an injection molding machine.
a hydraulic cylinder that produces the fluid pressure;
a flow path connecting a plurality of oil chambers of the hydraulic cylinder;
a dual rotating pump provided in the middle of the flow path;
a servomotor for controlling the rotation of the double-rotating pump;
The injection molding machine of claim 1, comprising:
The determination unit performs determination based on the predetermined threshold that is set in advance for each position to which the movable platen is moved.
The injection molding machine according to claim 1.
The determination unit determines whether or not the time required for the movable platen to reach a predetermined position exceeds a predetermined time.
The injection molding machine according to claim 1.
a pressure control unit that performs pressure control on the movable platen in the mold closing process;
a switching unit for switching 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;
When the pressure control unit performs the pressure control, the determination unit determines whether or not the time required to reach the predetermined position exceeds the predetermined time. When performing control, determining whether the pressure value obtained by the obtaining unit exceeds the predetermined threshold value,
The injection molding machine according to claim 4.
Further comprising a storage unit that stores the predetermined threshold,
wherein the predetermined threshold value stored in the storage unit is updated according to the pressure value acquired by the acquisition unit;
The injection molding machine according to claim 1.
The determination unit calculates an estimated value of pressure generated by movement of the movable platen from the rotation speed of the servomotor that generates the fluid pressure, and calculates the estimated value of the pressure and the pressure acquired by the acquisition unit. If the difference from the value is a predetermined value or more, determine that the predetermined threshold has been exceeded,
The injection molding machine according to claim 2.