CN116745095A

CN116745095A - Injection molding machine, control device and control method for injection molding machine

Info

Publication number: CN116745095A
Application number: CN202280009107.5A
Authority: CN
Inventors: 丸本洋嗣
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2021-03-31
Filing date: 2022-03-30
Publication date: 2023-09-12
Also published as: JPWO2022210979A1; WO2022210979A1; DE112022001896T5

Abstract

The invention provides a control device of an injection molding machine, which comprises a determining part, an acquiring part and an adjusting part. In the metering step of metering the molding material stored in the cylinder for injection molding, the determining unit determines the retraction speed of retracting the screw based on the metering position indicating the position of the screw in the cylinder after the movement for storing the molding material required for molding the molded article and a preset metering time. In the metering step, the acquisition unit acquires the back pressure of the screw when the screw is controlled according to the retraction speed and the preset rotation speed. The adjusting unit adjusts the rotation speed according to the back pressure.

Description

Injection molding machine, control device and control method for injection molding machine

Technical Field

The present invention relates to a control device for an injection molding machine, and a control method.

Background

In a conventional injection molding machine, the back pressure generated by rotating the screw to feed the molding material to the screw tip side is controlled to be constant in the metering step. However, in the metering step, depending on the type of molding material, a long time may be required until the back pressure reaches a certain value. When such a molding material is used, it is difficult to generate back pressure of the molding material against the screw. At this time, the molding may become unstable.

Accordingly, a technique for setting the retraction speed of the screw in place of the back pressure to mold a molded article has been proposed. For example, patent document 1 describes a technique of adjusting the rotation speed in the vicinity of the metering end position based on the positional deviation and the deviation of the back pressure after the backward movement and rotation control of the screw are performed at a predetermined speed.

Technical literature of the prior art

Patent literature

Patent document 1: japanese patent application laid-open No. 2004-154988

Disclosure of Invention

Technical problem to be solved by the invention

In the technique described in patent document 1, the accuracy of the measurement is improved by adjusting the deviation generated by the control using the preset reverse speed and rotation speed in the vicinity of the measurement end position. However, when the backward movement and rotation control of the screw are performed at a predetermined speed, there is a problem in that it is difficult to set the speed.

The present invention provides a technique for improving the molding stability of a molded product by setting the rotational speed and the retraction speed of a screw to appropriate values.

Means for solving the technical problems

The control device for an injection molding machine according to one aspect of the present invention includes a determination unit, an acquisition unit, and an adjustment unit. In the metering step of metering the molding material stored in the cylinder for injection molding, the determining unit determines the retraction speed of retracting the screw based on the metering position indicating the position of the screw in the cylinder after the movement for storing the molding material required for molding the molded article and a preset metering time. In the metering step, the acquisition unit acquires the back pressure of the screw when the screw is controlled according to the retraction speed and the preset rotation speed. The adjusting unit adjusts the rotation speed according to the back pressure.

Effects of the invention

According to one aspect of the present invention, the rotational speed and the retraction speed of the screw are set to appropriate values to improve the molding stability of the molded article.

Drawings

Fig. 1 is a diagram showing a state at the end of mold opening of an injection molding machine according to an embodiment.

Fig. 2 is a diagram showing a state at the time of mold closing of the injection molding machine according to the embodiment.

Fig. 3 is a diagram showing constituent elements of a control device according to an embodiment, with functional blocks.

Fig. 4 is a diagram illustrating a case where the back pressure obtained by the obtaining unit according to embodiment 1 is higher than the set back pressure.

Fig. 5 is a diagram illustrating a case where the back pressure obtained by the obtaining unit according to embodiment 1 is lower than 50% of the set back pressure.

Fig. 6 is a diagram illustrating a case where the back pressure obtained by the obtaining unit according to embodiment 1 is within a range of 50% to 100% of the set back pressure.

Fig. 7 is a flowchart showing a process for setting parameters used for controlling the reverse speed of the measuring step in the control device according to embodiment 1.

Fig. 8 is a flowchart showing a process of setting parameters when switching from back pressure control to reverse speed control in the measurement process in the control device according to embodiment 1.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding structures may be denoted by the same or corresponding symbols, and description thereof may be omitted.

Fig. 1 is a diagram showing a state at the end of mold opening of an injection molding machine according to an embodiment. Fig. 2 is a diagram showing a state at the time of mold closing of the injection molding machine according to the embodiment. In the present specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are directions perpendicular to each other. The X-axis direction and the Y-axis direction represent horizontal directions, and the Z-axis direction represents vertical directions. When the mold clamping device 100 is horizontal, 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 in the Y-axis direction is referred to as the operation side, and the positive side in the Y-axis direction is referred to as the opposite side to the operation side.

As shown in fig. 1 to 2, the injection molding machine 10 includes: a mold clamping device 100 for opening and closing the mold device 800; an ejector 200 for ejecting the molded article molded by the mold device 800; an injection device 300 injecting a molding material to the mold device 800; a moving device 400 for advancing and retreating the injection device 300 with respect to the mold device 800; a control device 700 for controlling the respective constituent elements of the injection molding machine 10; and a frame 900 for supporting the components of the injection molding machine 10. 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 mold clamping device frame 910 and the injection device frame 920 are respectively provided on the bottom plate 2 via horizontal adjustment casters 930. The control device 700 is disposed in the internal space of the injection device frame 920. The following describes the respective constituent elements of the injection molding machine 10.

(mold clamping device)

In the description of the mold clamping apparatus 100, the moving direction (for example, the positive X-axis direction) of the movable platen 120 during mold closing is set to the front, and the moving direction (for example, the negative X-axis direction) of the movable platen 120 during mold opening is set to the rear.

The mold clamping device 100 performs mold closing, pressure increasing, mold clamping, pressure releasing, and mold opening of the mold device 800. The mold apparatus 800 includes a stationary mold 810 and a movable mold 820.

The mold clamping device 100 is, for example, horizontal, and the mold opening/closing direction is horizontal. The mold clamping device 100 includes a fixed platen 110 to which a fixed mold 810 is attached, a movable platen 120 to which a movable mold 820 is attached, and a moving mechanism 102 that moves the movable platen 120 relative to the fixed platen 110 in a mold opening/closing direction.

The stationary platen 110 is fixed relative to the clamp frame 910. A stationary mold 810 is mounted on a surface of the stationary platen 110 opposite to the movable platen 120.

The movable platen 120 is disposed so as to be movable 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. The movable mold 820 is attached to a surface of the movable platen 120 facing the fixed platen 110.

The moving mechanism 102 performs mold closing, pressure increasing, mold closing, pressure releasing, and mold opening of the mold apparatus 800 by advancing and retracting the movable platen 120 relative to the fixed platen 110. The moving mechanism 102 includes a toggle base 130 disposed at a distance from the fixed platen 110, a link 140 connecting the fixed platen 110 and the toggle base 130, a toggle mechanism 150 moving the movable platen 120 relative to the toggle base 130 in the mold opening/closing direction, a mold clamping motor 160 operating the toggle mechanism 150, a motion conversion mechanism 170 converting the rotational motion of the mold clamping motor 160 into a linear motion, and a mold thickness adjustment mechanism 180 adjusting the distance between the fixed platen 110 and the toggle base 130.

The toggle seat 130 is disposed at a distance from the fixed platen 110, and is mounted on the clamping device frame 910 so as to be movable in the mold opening/closing direction. The toggle mount 130 may be configured to be movable along a guide provided on the clamp frame 910. The guide of the toggle seat 130 may be common to the guide 101 of the movable platen 120.

In the present embodiment, the stationary platen 110 is fixed to the clamping device frame 910, and the toggle mount 130 is disposed so as to be movable in the mold opening and closing direction with respect to the clamping device frame 910, but the toggle mount 130 may be fixed to the clamping device frame 910, and the stationary platen 110 may be disposed so as to be movable in the mold opening and closing direction with respect to the clamping device frame 910.

The connecting rod 140 connects the fixed platen 110 and the toggle base 130 with a space L therebetween in the mold opening and closing direction. Multiple (e.g., 4) connecting rods 140 may be used. The plurality of tie bars 140 are arranged parallel to the mold opening and closing direction and extend according to the mold clamping force. A link strain detector 141 detecting strain of the link 140 may be provided on at least 1 link 140. The link strain detector 141 transmits a signal indicating the detection result to the control device 700. The detection result of the tie bar strain detector 141 is used for detection of the clamping force or the like.

In the present embodiment, the tie bar strain detector 141 is used as a mold clamping force detector for detecting a mold clamping force, but the present invention is not limited thereto. The mold clamping force detector is not limited to the strain gauge type, but may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and the mounting position thereof is not limited to the tie bar 140.

The toggle mechanism 150 is disposed between the movable platen 120 and the toggle base 130, and moves the movable platen 120 with respect to the toggle base 130 in the mold opening and closing direction. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening and closing direction, and a pair of link groups that are bent and extended by the movement of the crosshead 151. The pair of link groups includes a 1 st link 152 and a 2 nd link 153, which are connected to each other by a pin or the like so as to be freely bendable. The 1 st link 152 is attached to the movable platen 120 by a pin or the like so as to be swingable. The 2 nd link 153 is attached to the toggle base 130 by a pin or the like so as to be swingable. The 2 nd link 153 is attached to the crosshead 151 via the 3 rd link 154. When the crosshead 151 is advanced and retracted relative to the toggle mount 130, the 1 st link 152 and the 2 nd link 153 are extended and retracted to advance and retract the movable platen 120 relative to the toggle mount 130.

The structure of the toggle mechanism 150 is not limited to the structure shown in fig. 1 and 2. For example, in fig. 1 and 2, the number of nodes of each link group is 5, but may be 4, or one end of the 3 rd link 154 may be connected to the node of the 1 st link 152 and the 2 nd link 153.

The clamp motor 160 is mounted to the toggle mount 130 and operates the toggle mechanism 150. The clamp motor 160 advances and retreats the crosshead 151 with respect to the toggle mount 130, and stretches the 1 st link 152 and the 2 nd link 153 to advance and retreat the movable platen 120 with respect to the toggle mount 130. The mold clamping motor 160 is directly connected to the motion conversion mechanism 170, but may be connected to the motion conversion mechanism 170 via a belt, pulley, or the like.

The motion conversion mechanism 170 converts the rotational motion of the clamp motor 160 into a linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

The mold clamping device 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure releasing process, a mold opening process, and the like under the control of the control device 700.

In the mold closing step, the movable platen 120 is advanced by driving the mold clamping motor 160 to advance the crosshead 151 to the mold closing end position at a set movement speed so that the movable mold 820 is brought into contact with the fixed mold 810. For example, the position and the moving speed of the crosshead 151 are detected using a clamp motor encoder 161 or the like. The clamp motor encoder 161 detects the rotation of the clamp motor 160, and transmits a signal indicating the detection result to the control device 700.

The crosshead position detector for detecting the position of the crosshead 151 and the crosshead moving speed detector for detecting the moving speed of the crosshead 151 are not limited to the clamp motor encoder 161, and a conventional detector may be used. The movable platen position detector for detecting the position of the movable platen 120 and the movable platen moving speed detector for detecting the moving speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and a conventional detector may be used.

In the pressure increasing step, the clamping motor 160 is further driven to further advance the crosshead 151 from the mold closing end position to the clamping position, thereby generating clamping force.

In the mold clamping process, the mold clamping motor 160 is driven to maintain the position of the crosshead 151 at the mold clamping position. In the mold clamping step, the mold clamping force generated in the pressure increasing step is maintained. In the mold clamping step, 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. The filled molding material is cured, thereby obtaining a molded article.

The number of cavity spaces 801 may be 1 or more. In the latter case, a plurality of molded articles can be obtained at the same time. An insert may be disposed in a portion of the cavity space 801 and another portion of the cavity space 801 may be filled with molding material. A molded article in which the insert and the molding material are integrated can be obtained.

In the decompression step, the clamping motor 160 is driven to retract the crosshead 151 from the clamping position to the mold opening start position, and the movable platen 120 is retracted to reduce the clamping force. The mold opening start position and the mold closing end position may be the same position.

In the mold opening step, the movable platen 120 is retracted by driving the mold clamping motor 160 to retract the crosshead 151 from the mold opening start position to the mold opening end position at a set movement speed, so that the movable mold 820 is separated from the fixed mold 810. Then, the ejector 200 ejects the molded article from the mold 820.

The setting conditions in the mold closing step, the pressure increasing step, and the mold closing step are set in a unified manner as a series of setting conditions. For example, the moving speed, the position (including the mold closing start position, the moving speed switching position, the mold closing end position, and the mold clamping position) and the mold clamping force of the crosshead 151 in the mold closing step and the pressure increasing step are set in a unified manner as a series of setting conditions. The mold closing start position, the moving speed switching position, the mold closing end position, and the mold closing position are arranged in this order from the rear side to the front side, and indicate the start point and the end point of the section in which the moving speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The moving speed switching position may not be set. Only one of the mold clamping position and the mold clamping force may be set.

The conditions for setting in the decompression step and the mold opening step are set in the same manner. For example, the moving speed and the position (the mold opening start position, the moving speed switching position, and the mold opening end position) of the crosshead 151 in the decompression step and the mold opening step are set in a unified manner as a series of setting conditions. The mold opening start position, the movement speed switching position, and the mold opening end position are arranged in this order from the front side to the rear side, and indicate the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The moving speed switching position may not be set. The mold opening start position and the mold closing end position may be the same position. The mold opening end position and the mold closing start position may be the same position.

In addition, instead of the moving speed, position, etc. of the crosshead 151, the moving speed, position, etc. of the movable platen 120 may be set. In addition, the clamping force may be set instead of the position of the crosshead (for example, the clamping position) and the position of the movable platen.

However, the toggle mechanism 150 amplifies the driving force of the clamp motor 160 and transmits it to the movable platen 120. Its magnification is also called toggle magnification. The toggle magnification changes according to an angle θ (hereinafter, also referred to as "link angle θ") formed by the 1 st link 152 and the 2 nd link 153. The link angle θ is obtained from the position of the crosshead 151. When the link angle θ is 180 °, the toggle magnification becomes maximum.

When the thickness of the mold device 800 changes due to replacement of the mold device 800, temperature change of the mold device 800, or the like, mold thickness adjustment is performed to obtain a predetermined clamping force at the time of clamping. In the die thickness adjustment, for example, the interval L between the fixed platen 110 and the toggle base 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the point in time when the movable die 820 contacts the fixed die 810.

The mold clamping device 100 has a mold thickness adjusting mechanism 180. The die thickness adjustment mechanism 180 adjusts the distance L between the fixed platen 110 and the toggle base 130, thereby performing die thickness adjustment. The timing of the mold thickness adjustment is performed, for example, during a period from the end of the molding cycle to the start of the next molding cycle. The die thickness adjusting mechanism 180 includes, for example: a screw shaft 181 formed at a rear end portion of the connection rod 140; a screw nut 182 rotatably held in the toggle seat 130 and being non-retractable; and a die thickness adjusting motor 183 for rotating a screw nut 182 screwed to the screw shaft 181.

A screw shaft 181 and a screw nut 182 are provided for each of the connection rods 140. The rotational driving force of the die thickness adjusting motor 183 may be transmitted to the plurality of lead screw nuts 182 via the rotational driving force transmitting portion 185. A plurality of lead screw nuts 182 can be rotated synchronously. Further, by changing the transmission path of the rotational driving force transmission unit 185, the plurality of lead screw nuts 182 can be rotated individually.

The rotational driving force transmitting portion 185 is constituted by a gear or the like, for example. At this time, driven gears are formed on the outer periphery of each screw nut 182, a driving gear is mounted on the output shaft of the die thickness adjusting motor 183, and an intermediate gear engaged with the driven gears and the driving gear is rotatably held at the center portion of the toggle seat 130. In addition, the rotational driving force transmitting portion 185 may be formed of a belt, a pulley, or the like instead of the gear.

The operation of the die thickness adjusting mechanism 180 is controlled by the control device 700. The control device 700 drives the die thickness adjustment motor 183 to rotate the lead screw nut 182. As a result, the position of the toggle housing 130 relative to the connecting rod 140 is adjusted, and the interval L between the fixed platen 110 and the toggle housing 130 is adjusted. In addition, a plurality of die thickness adjusting mechanisms may be used in combination.

The interval L is detected using a die thickness adjustment motor encoder 184. The die thickness adjustment motor encoder 184 detects the rotation amount and rotation direction of the die thickness adjustment motor 183, and transmits a signal indicating the detection result to the control device 700. The detection result of the die thickness adjustment motor encoder 184 is used to monitor and control the position of the toggle seat 130, the spacing L. The toggle seat position detector for detecting the position of the toggle seat 130 and the interval detector for detecting the interval L are not limited to the die thickness adjusting motor encoder 184, and a conventional detector may be used.

The mold clamping device 100 may have a mold temperature regulator that regulates the temperature of the mold device 800. The die device 800 has a flow path for the temperature control medium therein. The mold temperature regulator regulates the temperature of the temperature regulating medium supplied to the flow path of the mold device 800, thereby regulating the temperature of the mold device 800.

The mold clamping device 100 of the present embodiment is a horizontal mold opening/closing direction, but may be a vertical mold opening/closing direction.

The mold clamping device 100 of the present embodiment includes the mold clamping motor 160 as a driving source, but may include a hydraulic cylinder instead of the mold clamping motor 160. The mold clamping device 100 may include a linear motor for mold opening and closing, or may include an electromagnet for mold clamping.

(ejector device)

In the description of the ejector 200, the moving direction (for example, the positive X-axis direction) of the movable platen 120 during mold closing is set to the front, and the moving direction (for example, the negative X-axis direction) of the movable platen 120 during mold opening is set to the rear, similarly to the description of the mold clamping device 100 and the like.

The ejector 200 is attached to the movable platen 120 and advances and retreats together with the movable platen 120. The ejector 200 includes: an ejector rod 210 ejecting the molded article from the mold device 800; and a driving mechanism 220 for moving the ejector rod 210 in the moving direction (X-axis direction) of the movable platen 120.

The ejector rod 210 is disposed so as to be movable in and out of the through hole of the movable platen 120. The front end of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The tip end of the ejector rod 210 may or may not be connected to the ejector plate 826.

The driving mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts rotational motion of the ejector motor into linear motion of the ejector rod 210. The motion conversion mechanism comprises a screw shaft and a screw nut screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

The ejector 200 performs the ejection process under the control of the control device 700. In the ejection step, the ejector rod 210 is advanced from the standby position to the ejection position at a set movement speed, and the ejector plate 826 is advanced to eject the molded article. Then, the ejector motor is driven to retract the ejector rod 210 at a set movement speed, and the ejector plate 826 is retracted to the original standby position.

The position and moving speed of the ejector rod 210 are detected, for example, using an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and transmits a signal indicating the detection result to the control device 700. The ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod movement speed detector that detects the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and a conventional detector may be used.

(injection device)

In the description of the injection device 300, the direction of movement of the screw 330 (for example, the negative X-axis direction) during filling is set to the front, and the direction of movement of the screw 330 (for example, the positive X-axis direction) during metering is set to the rear, unlike the description of the mold clamping device 100 and the description of the ejector 200.

The injection device 300 is provided on the slide base 301, and the slide base 301 is disposed so as to be movable relative to the injection device frame 920. The injection device 300 is disposed so as to be movable in and out of the mold device 800. The injection device 300 is in contact with the mold device 800 and fills the cavity space 801 in the mold device 800 with molding material. The injection device 300 includes, for example, a cylinder 310 for heating a molding material, a nozzle 320 provided at a distal end portion of the cylinder 310, a screw 330 rotatably disposed in the cylinder 310, a metering motor 340 for rotating the screw 330, an injection motor 350 for advancing and retreating the screw 330, and a load detector 360 for detecting a load transmitted between the injection motor 350 and the screw 330.

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

The cylinder 310 is divided into a plurality of regions along an axial direction (e.g., an X-axis direction) of the cylinder 310. The heater 313 and the temperature detector 314 are provided in each of the plurality of regions. The control device 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 presses the die 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.

The screw 330 is rotatably disposed in the cylinder 310 and is movable forward and backward. When the screw 330 is rotated, the molding material is conveyed forward along the spiral groove of the screw 330. The molding material is gradually melted by heat from the cylinder 310 while being conveyed forward. As the molding material in the liquid state is conveyed to the front of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. Then, when the screw 330 is advanced, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled in the mold device 800.

The check ring 331 is attached to the front of the screw 330 so as to be movable forward and backward, and the check ring 331 serves as a check valve to prevent the molding material from flowing backward from the front of the screw 330 when the screw 330 is pushed forward.

When the screw 330 is advanced, the check ring 331 is pushed rearward by the pressure of the molding material in front of the screw 330, and retreats relatively to the screw 330 to a closed position (see fig. 2) blocking the flow path of the molding material. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

On the other hand, when the screw 330 is rotated, the check ring 331 is pushed forward by the pressure of the molding material conveyed forward along the spiral groove of the screw 330, and relatively advances to the open position (refer to fig. 1) for opening the flow path of the molding material with respect to the screw 330. Thereby, the molding material is conveyed to the front of the screw 330.

Check ring 331 may be either a co-rotating type that rotates with screw 330 or a non-co-rotating type that does not rotate with screw 330.

In addition, the injection device 300 may have a driving source that advances and retreats the check 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 driving source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump.

Injection motor 350 advances and retracts screw 330. A motion conversion mechanism or the like for converting the rotational motion of injection motor 350 into the linear motion of screw 330 is provided between injection motor 350 and screw 330. The motion conversion mechanism includes, for example, a screw shaft and a screw nut screwed to the screw shaft. Balls, rollers, etc. may be provided between the screw shaft and the screw nut. The driving source for advancing and retreating the screw 330 is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder or the like.

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

The load detector 360 transmits a signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into a pressure acting between the screw 330 and the molding material, and 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 acting on the molding material from the screw 330, and the like.

The pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a conventional detector can be used. For example, a nozzle pressure sensor or an in-mold pressure sensor may be used. The nozzle pressure sensor is provided to the nozzle 320. The mold internal pressure sensor is provided inside the mold device 800.

The injection device 300 performs a metering process, a filling process, a pressure maintaining process, and the like under the control of the control device 700. The filling step and the pressure maintaining step may be collectively referred to as an injection step.

In the metering step, the metering motor 340 is driven to rotate the screw 330 at a set rotational speed, and the molding material is conveyed forward along the spiral groove of the screw 330. Thereby, the molding material is gradually melted. As the molding material in the liquid state is conveyed to the front of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. The rotational speed of screw 330 is detected, for example, using a metering motor encoder 341. The metering motor encoder 341 detects the rotation of the metering motor 340 and transmits a signal indicating the detection result to the control device 700. 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 conventional detector can be used.

In the metering step, injection motor 350 may be driven to apply a set back pressure to screw 330 in order to limit rapid retraction of screw 330. The back pressure on the screw 330 is detected, for example, using a load detector 360. When the screw 330 is retracted to the metering end position and a predetermined amount of molding material is accumulated in front of the screw 330, the metering process ends.

The position and the rotation speed of the screw 330 in the moving direction in the measuring step are set in a unified manner as a series of setting conditions. For example, a measurement start position, a rotation speed switching position, and a measurement end position are set. These positions are arranged in order from the front side to the rear side, and indicate the start point and the end point of the section in which the rotational speed is set. The rotational speed is set for each section. The number of rotational speed switching positions may be 1 or a plurality of rotational speed switching positions. The rotational speed switching position may not be set. Back pressure is set for each section.

In the filling step, the injection motor 350 is driven to advance the screw 330 at a set moving speed, and the cavity space 801 in the mold apparatus 800 is filled with the liquid molding material stored in front of the screw 330. The position and moving speed of the screw 330 are detected, for example, using the injection motor encoder 351. The injection motor encoder 351 detects the rotation of the injection motor 350 and transmits a signal indicating the detection result thereof to the control device 700. When the position of the screw 330 reaches the set position, the filling process is switched to the pressure maintaining process (so-called V/P switching). The position where the V/P switch is performed is also referred to as a V/P switch position. The set moving speed of the screw 330 may be changed according to the position, time, etc. of the screw 330.

The position and the moving speed of the screw 330 in the filling process are set uniformly as a series of setting conditions. For example, a filling start position (also referred to as 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 indicate the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The movement speed switching position may not 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 the screw 330 is detected by a load detector 360. When the pressure of the screw 330 is below the set pressure, the screw 330 advances at the set moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is advanced at a movement speed slower than the set movement speed so that the pressure of the screw 330 becomes equal to or lower than the set pressure in order to protect the mold.

In the filling step, after the position of the screw 330 reaches the V/P switching position, the screw 330 may be suspended at the V/P switching position and then V/P switching may be performed. Instead of stopping the screw 330, the screw 330 may be advanced at a slight speed or retracted at a slight speed immediately before the V/P switching. The screw position detector for detecting the position of the screw 330 and the screw movement speed detector for detecting the movement speed of the screw 330 are not limited to the injection motor encoder 351, and a conventional detector may be used.

In the pressure maintaining step, the injection motor 350 is driven to push the screw 330 forward, and the pressure of the molding material at the tip end portion of the screw 330 (hereinafter, also referred to as "holding pressure") is maintained at a set pressure, so that the molding material remaining in the cylinder 310 is pushed to the mold device 800. An insufficient amount of molding material due to cooling shrinkage in the mold device 800 can be replenished. The holding pressure is detected, for example, using a load detector 360. The set value of the holding pressure may be changed according to the elapsed time from the start of the pressure-maintaining process. The holding pressure and the holding time for holding the holding pressure in the plurality of holding pressure steps may be set individually or may be set collectively as a series of setting conditions.

In the pressure maintaining step, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and at the end of the pressure maintaining step, the inlet of the cavity space 801 is blocked by the solidified molding material. This state is called gate sealing, and prevents backflow of molding material from the cavity space 801. After the pressure maintaining process, a cooling process is started. In the cooling step, solidification of the molding material in the cavity space 801 is performed. The metering step may be performed in the cooling step in order to shorten the molding cycle time.

The injection device 300 of the present embodiment is of a coaxial screw type, but may be of a pre-molding type or the like. The injection device of the pre-molding method supplies the molding material melted in the plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into the mold device. In the plasticizing cylinder, the screw is rotatably disposed so as not to advance and retreat, or the screw is rotatably disposed so as to advance and retreat. On the other hand, in the injection cylinder, the plunger is disposed so as to be movable forward and backward.

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 either horizontal or vertical.

(Mobile device)

In the description of the moving device 400, the moving direction of the screw 330 (for example, the X-axis negative direction) during filling is set to the front, and the moving direction of the screw 330 (for example, the X-axis positive direction) during metering is set to the rear, as in the description of the injection device 300.

The movement device 400 advances and retracts the injection device 300 relative to the mold device 800. The moving device 400 presses the nozzle 320 against the die device 800 to generate a nozzle contact pressure. The traveling apparatus 400 includes a hydraulic pump 410, a motor 420 as a driving source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

The hydraulic pump 410 has a 1 st port 411 and a 2 nd port 412. The hydraulic pump 410 is a pump capable of rotating in both directions, and generates hydraulic pressure by switching the rotation direction of the motor 420 so that a working fluid (for example, oil) is sucked from one of the 1 st port 411 and the 2 nd port 412 and discharged from the other port. The hydraulic pump 410 may suck the working fluid from the tank and discharge the working fluid from any one of the 1 st port 411 and the 2 nd port 412.

The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 by a rotation direction and a torque corresponding to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servo motor.

Hydraulic cylinder 430 has a cylinder body 431, a piston 432, and a piston rod 433. Cylinder body 431 is fixed relative to injection device 300. Piston 432 divides the interior of cylinder body 431 into a front chamber 435 that is a 1 st chamber and a rear chamber 436 that is a 2 nd chamber. The piston rod 433 is fixed with respect to the fixed platen 110.

The front chamber 435 of the hydraulic cylinder 430 is connected to the 1 st port 411 of the hydraulic pump 410 via the 1 st flow path 401. The working fluid discharged from the 1 st port 411 is supplied to the front chamber 435 via the 1 st flow path 401, and the injection device 300 is pushed 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 a nozzle contact pressure of the nozzle 320 by the pressure of the working fluid supplied from the hydraulic pump 410.

On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the 2 nd port 412 of the hydraulic pump 410 via the 2 nd flow path 402. The working fluid discharged from the 2 nd port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the 2 nd flow path 402, whereby the injection device 300 is pushed rearward. The injection device 300 is retracted and the nozzle 320 is separated from the stationary mold 810.

In the present 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 rotational motion of the electric motor into linear motion of the injection device 300 may be used.

(control device)

As shown in fig. 1 to 2, the control device 700 is configured by a computer, for example, and includes a CPU (Central Processing Unit: central processing unit) 701, a storage medium 702 such as a memory, an input interface 703, and an output interface 704. The control device 700 performs various controls by causing the CPU701 to execute a program stored in the storage medium 702. The control device 700 receives a signal from the outside through the input interface 703 and transmits a signal to the outside through the output interface 704.

The control device 700 repeatedly performs a metering process, a mold closing process, a pressure increasing process, a mold closing process, a filling process, a pressure maintaining process, a cooling process, a pressure releasing process, a mold opening process, an ejection process, and the like, to thereby repeatedly manufacture a molded product. A series of operations for obtaining a molded product, for example, an operation from the start of a metering process to the start of the next metering process is also referred to as "injection" or "molding cycle". The time required for one shot is also referred to as "molding cycle time" or "cycle time".

The one-shot molding cycle includes, for example, a metering step, a mold closing step, a pressure increasing step, a mold closing step, a filling step, a pressure maintaining step, a cooling step, a pressure releasing step, a mold opening step, and an ejection step in this order. The sequence here is the sequence in which the respective steps are started. The filling step, the pressure maintaining step and the cooling step are performed during the mold closing step. The start of the mold clamping process may be coincident with the start of the filling process. The end of the decompression step corresponds to the start of the mold opening step.

In addition, a plurality of steps may be performed simultaneously for the purpose of shortening the molding cycle time. For example, the metering step may be performed in the cooling step of the previous molding cycle, or may be performed during the mold clamping step. In this case, the mold closing step may be performed at the beginning of the molding cycle. The filling process may be started in the mold closing process. The ejection step may be started in the mold opening step. When an opening/closing valve for opening/closing the flow path of the nozzle 320 is provided, the mold opening process may be started in the metering process. Even if the mold opening process is started in the metering process, the molding material does not leak from the nozzle 320 as long as the opening/closing valve closes the flow path of the nozzle 320.

The one-shot molding cycle may include steps other than the metering step, the mold closing step, the pressure increasing step, the mold closing step, the filling step, the pressure maintaining step, the cooling step, the pressure releasing step, the mold opening step, and the ejection step.

For example, the pre-metering suck-back step of retracting the screw 330 to a preset metering start position may be performed after the end of the pressure maintaining step and before the start of the metering step. The pressure of the molding material stored in front of the screw 330 can be reduced before the start of the metering process, and the screw 330 can be prevented from rapidly backing up when the metering process is started.

After the completion of the metering step and before the start of the filling step, the post-metering suck-back step of retracting the screw 330 to a preset filling start position (also referred to as "injection start position") may be performed. The pressure of the molding material stored in front of the screw 330 can be reduced before the start of the filling process, and leakage of the molding material from the nozzle 320 can be prevented before the start of the filling process.

The control device 700 is connected to an operation device 750 that receives an input operation from a user and a display device 760 that displays a screen. The operation device 750 and the display device 760 are constituted by, for example, 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. Information such as the setting of the injection molding machine 10, the current state of the injection molding machine 10, and the like may be displayed on the screen of the touch panel 770. Further, an operation unit such as a button or an input field for receiving an input operation by a user may be displayed on the screen of the touch panel 770. The touch panel 770 as the operation device 750 detects an input operation of a user on a screen, and outputs a signal corresponding to the input operation to the control device 700. Thus, for example, the user can perform setting (including input of a set value) of the injection molding machine 10 by operating the operation unit provided on the screen while checking information displayed on the screen. The user can operate the operation unit provided on the screen, and thereby operate the injection molding machine 10 corresponding to the operation unit. The operation of the injection molding machine 10 may be, for example, the operations (including stopping) of the mold clamping device 100, the ejector 200, the injection device 300, the moving device 400, and the like. The operation of the injection molding machine 10 may be, for example, switching of a screen displayed on the touch panel 770 as the display device 760.

The operation device 750 and the display device 760 according to the present embodiment are integrated into the touch panel 770, but may be provided independently. Further, 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 device 100 (more specifically, the stationary platen 110).

Fig. 3 is a diagram showing constituent elements of a control device 700 according to an embodiment, with functional blocks. The functional blocks illustrated in fig. 3 are conceptual functional blocks, and are not necessarily physically configured as illustrated. All or part of the functional blocks may be functionally or physically distributed/integrated in arbitrary units. All or any part of the processing functions performed in the respective functional blocks are realized by programs executed by the CPU 701. Alternatively, each functional block may be implemented as hardware based on wired logic. As shown in fig. 3, the control device 700 includes a setting information storage unit 711, an input processing unit 712, a determination unit 713, an acquisition unit 714, a control unit 715, and an adjustment unit 716. The setting information storage 711 stores various parameters subjected to input processing, adjustment, and the like. The input processing unit 712 processes information input by the user via the operation device 750. In the injection molding, the determining unit 713 determines the retraction speed at which the screw 330 is retracted, based on a metering position indicating the position of the screw in the cylinder for determining the amount of molding material required for molding the molded article and a preset metering time in the metering step for metering the molding material stored in the cylinder 310. The detecting unit 604 detects the back pressure of the screw 330 when the measuring process is performed at the reverse speed and the rotational speed. The adjustment unit 716 adjusts the rotation speed according to the back pressure. The specific description of each structure will be described later.

Next, the operation of the injection molding machine 10 will be described.

In the metering step, the metering motor 340 is rotationally driven, and the screw 330 is rotated. In accordance with this rotation, the screw 330 is operated with its thread (thread), and the resin particles (solid molding material) filled in the thread groove of the screw 330 are conveyed forward. The resin particles are gradually melted by being heated by heat or the like from the heater 313 through the cylinder 310 while moving forward in the cylinder 310. Then, the resin particles are in a completely melted state in the front end portion of the cylinder 310. Then, as the molding material (resin) in a liquid state is conveyed to the front of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted.

In the metering process of the present embodiment, the control device 700 controls the injection motor 350 to retract the screw 330 at a predetermined retraction speed, and controls the metering motor 340 to rotate the screw 330 at a predetermined rotation speed.

The injection motor encoder 351 detects the rotation of the injection motor 350 and transmits a signal indicating the detection result thereof to the control device 700. The screw reverse speed detector that detects the reverse speed of the screw 330 is not limited to the injection motor encoder 351, and a conventional detector can be used. Thus, the control device 700 can control the screw 330 to have a predetermined backward speed.

The metering motor encoder 341 detects the rotation of the metering motor 340 and transmits a signal indicating the detection result to the control device 700. 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 conventional detector can be used. Thus, the control device 700 can control the screw 330 to have a predetermined rotational speed.

The load detector 360 detects the back pressure on the screw 330 and transmits a signal indicating the detection result to the control device 700. The load detector for detecting the back pressure of the screw 330 can use a conventional detector.

The control device 700 of the present embodiment adjusts the rotation speed of the screw 330 so that the back pressure detected by the load detector 360 becomes an appropriate value in the latter half of the measurement process.

That is, in the normal metering step, the back pressure is controlled to be constant, but the measurement may be ended before the back pressure of the molding material is constant, depending on the type of the molding material, the size of the molded article, and the like. In this case, the retraction speed and the rotation speed of the screw 330 are preset, but this setting is difficult for the user, and requires man-hours and experience. Therefore, the molding material may be under-filled or over-filled into the mold device 800 according to the setting.

Therefore, the control device 700 according to the present embodiment reduces the load of setting the reverse speed and the rotation speed.

The input processing unit 712 inputs parameters and the like set by the user via the operation device 750 and necessary for molding the molded product. For example, the input processing unit 712 performs input processing on settings related to the metering position, the cooling time, the set back pressure, and the cycle.

For example, the user determines the cooling time required for cooling the molded product according to the type of molding material, the thickness of the molded product, and the like, and the user inputs the cooling time from the operation device 750. In the present embodiment, an example in which the cooling time is input by the user is described, but the cooling time may be automatically set. For example, the input processing unit 712 may input the thickness of the processed molded product, the type of the molding material, and the like, and the determining unit 713 may determine the cooling time based on the thickness of the molded product, the type of the molding material, and the like.

The metering position shows the position of the screw 330 in the cylinder 310 at the end of the metering step, in other words, the position of the screw 330 after the movement for accumulating the molding material necessary for molding the molded article, in the metering step for metering the molding material accumulated in the cylinder 310. The metering position is set according to the metering start position of the screw 330 and the stroke amount of the screw 330 for accumulating the molding material required for molding the molded product. The metering start position is set according to the embodiment. The stroke amount of the screw 330 can be derived from the weight of the molded article. Therefore, the user can determine the metering position at the end of metering from the start position and the stroke amount at the time of metering of the screw 330.

The user determines the setting back pressure according to the type of molding material, the shape of the molded article, and the like. Then, the user inputs a set back pressure from the operation device 750. The set back pressure is set to a value set as a reference of the back pressure detected at the end of the measurement. In the present embodiment, the rotation speed of the screw 330 and the like need to be adjusted so that the back pressure becomes 50% to 100% of the set back pressure at the end of the measurement.

The determining section 713 determines the cooling time of the input process as the metering time.

In the metering step of metering the molding material stored in the cylinder 310, the determining unit 713 determines the withdrawal speed of the screw 330 for storing the molding material, which moves in the cylinder 310, based on the metering position set based on the amount of the molding material filled for molding the molded article and the metering time set based on the cooling time. As described above, the stroke amount is set according to the metering position. Therefore, for example, the determination unit 713 can determine the reverse speed by dividing the stroke amount by the measurement time.

The input processing unit 712 performs a process of inputting an initial value of the rotational speed of the screw 330 from the user. The initial value of the rotational speed of the screw 330 is set to a value set by the user according to the type of molding material, the amount of molding material, and the like. The initial value of the rotation speed is not limited to the example set by the user, and the determination unit 713 may determine the rotation speed stored in advance as the initial value of the rotation speed, for example. The rotation speed is adjusted to an appropriate value by the following configuration. Therefore, the initial value of the rotation speed may be an arbitrary value.

The setting information storage 711 stores information necessary for the measurement process. For example, the setting information storage 711 stores the setting back pressure, the reverse speed, and the rotational speed. The stored set back pressure is set to a value input to the processing unit 712. The stored retraction speed is set to a value determined by the determination unit 713. The stored rotation speed may be the rotation speed input through the input processing portion 712. The stored rotation speed is updated each time it is adjusted by the adjusting unit 716.

The setting information storage 711 of the present embodiment stores the set back pressure, the reverse speed, and the adjusted rotational speed. Accordingly, the subsequent processing can automate the setting for molding the molded article by reading the parameters from the setting information storage 711.

The acquisition unit 714 acquires the retraction speed of the screw 330 based on the rotation speed of the injection motor 350 detected by the injection motor encoder 351. The acquisition unit 714 acquires the actual rotation speed of the screw 330 from the rotation speed of the metering motor 340 detected by the metering motor encoder 341.

The control unit 715 controls the injection motor 350 so that the actual retraction speed of the screw 330 acquired by the acquisition unit 714 becomes the retraction speed stored in the setting information storage unit 711.

The control unit 715 controls the metering motor 340 so that the actual rotation speed of the screw 330 acquired by the acquisition unit 714 becomes the rotation speed stored in the setting information storage unit 711.

Then, in the metering step, the acquisition unit 714 acquires the back pressure of the screw 330 from the load detector 360 when the control unit 715 controls the screw 330 at the retraction speed and the preset rotation speed. The acquisition unit 714 according to the present embodiment acquires the back pressure at the end of the measurement process.

The adjusting unit 716 adjusts the rotation speed based on the back pressure obtained at the end of the metering process. In the present embodiment, the adjustment unit 716 adjusts the rotation speed so that the back pressure detected at the end of the measurement process falls within a range of 50% to 100% of the set back pressure set as a reference at the end of the measurement. In the next injection molding metering step, the control unit 715 controls the metering motor 340 so that the rotational speed is adjusted. By repeating this process, the rotation speed can be adjusted so that the back pressure detected at the end of the metering process is limited.

In the present embodiment, since the back pressure detected at the start of the measurement is unstable, the rotation speed is adjusted based on the back pressure acquired at the end of the measurement.

Fig. 4 is a diagram illustrating a case where the back pressure acquired by the acquisition unit 714 according to the present embodiment is higher than the set back pressure. In the example shown in fig. 4, the rotational speed 1401, the measurement position 1402, and the back pressure 1403 are set. As shown by the rotation speed 1401, the control unit 715 controls the metering motor 340 to increase the rotation speed R1 of the screw 330 from the metering start time '0', and thereafter maintains the rotation speed R1. Along with this rotation control, as shown in a metering position 1402, the control unit 715 controls the injection motor 350 to retract the screw 330 to a metering position Pf at a metering end time tf. Then, the control section 715 ends the backward movement control of the screw 330, and reduces the rotational speed to '0'. The measurement time from the start of measurement to the measurement end time tf is set to be equal to or shorter than the cooling time.

In the example shown in fig. 4, at the measurement end time tf, the acquisition unit 714 acquires a back pressure that is 100% higher than the set back pressure (see back pressure 1403 in fig. 4). Therefore, the adjustment unit 716 determines that the filling is excessive, and adjusts the next rotation speed to be lower than the rotation speed R1.

Fig. 5 is a diagram illustrating a case where the back pressure acquired by the acquisition unit 714 according to the present embodiment is 50% lower than the set back pressure. In the example shown in fig. 5, the rotation speed 1501 and the back pressure 1503 are set. The reverse speed is the same as in fig. 4, so metering position 1402 is the same as in fig. 4. As shown by the rotation speed 1501, the control unit 715 controls the metering motor 340 to increase the rotation speed R2 of the screw 330 from the metering start time '0' (rotation speed R2 < rotation speed R1), and then maintains the rotation speed R2. Along with this rotation control, as shown in a metering position 1402, the control unit 715 controls the injection motor 350 to retract the screw 330 to a metering position Pf at a metering end time tf. Then, the control section 715 ends the backward movement control of the screw 330, and reduces the rotational speed to '0'.

In the example shown in fig. 5, at the measurement end time tf, the acquisition unit 714 acquires a back pressure 50% lower than the set back pressure (see back pressure 1503 in fig. 5). Therefore, the adjustment unit 716 determines that the filling is too small, and adjusts the next rotation speed to be higher than the rotation speed R2.

Fig. 6 is a diagram illustrating a case where the back pressure acquired by the acquisition unit 714 according to the present embodiment is within a range of 50% to 100% of the set back pressure. In the example shown in fig. 6, the rotation speed 1601 and the back pressure 1603 are set. The retraction speed is the same as in fig. 4 and 5, and therefore the metering position 1402 is the same as in fig. 4 and 5. As shown by the rotation speed 1601, the control unit 715 controls the metering motor 340 to increase the rotation speed R3 of the screw 330 from the metering start time '0' (rotation speed R2 < rotation speed R3 < rotation speed R1), and then maintains the rotation speed R3. Along with this rotation control, as shown in a metering position 1402, the control unit 715 controls the injection motor 350 to retract the screw 330 to a metering position Pf at a metering end time tf. Then, the control section 715 ends the backward movement control of the screw 330, and reduces the rotational speed to '0'.

At the measurement end time tf, the acquisition unit 714 acquires a back pressure in the range of 50% to 100% of the set back pressure (see back pressure 1603 in fig. 6). Accordingly, the adjusting unit 716 determines that the rotational speed is adjusted to an appropriate rotational speed, and stores the rotational speed R3 in the setting information storage unit 711. Thereby, the adjustment of the rotation speed is ended.

Next, the setting process of the parameters used for controlling the reverse speed of the measurement process in the control device 700 will be described. Fig. 7 is a flowchart showing a process for setting parameters used for controlling the reverse speed of the measurement process in the control device 700 according to the present embodiment. The type and cycle of the molded article and the molding material are determined before the parameters are set.

First, the input processing unit 712 performs a process of inputting parameters and the like necessary for molding the molded product by the user via the operation device 750 (step S701). Examples of the parameters include settings related to setting back pressure, cooling time, metering position, initial value of rotational speed, and cycle.

The determining unit 713 determines the cooling time as the measurement time, and calculates the initial retraction speed of the screw 330 moving in the cylinder 310 based on the measurement position and the measurement time (step S702). The measured time is stored in the setting information storage unit 711.

Then, the control unit 715 controls the molding process including the metering step of retracting the screw 330 at the initial retraction speed (step S703).

Then, the determining unit 713 adjusts the retraction speed so that the measurement is completed within the measurement period based on the control result of the molding process in step S703 (step S704: an example of the determining process). The adjusted reverse speed is stored in the setting information storage unit 711.

Then, the control unit 715 controls the molding process including the metering step of retracting the screw 330 at the retraction speed adjusted in step S704 (step S705).

The acquisition unit 714 acquires the back pressure at the measurement end time tf from the load detector 360 (step S706: an example of the acquisition process).

The adjusting unit 716 determines whether the acquired back pressure is within a range of 50% to 100% of the set back pressure (step S707).

When it is determined that the acquired back pressure is out of the range of 50% to 100% of the set back pressure (step S707: no), the adjusting unit 716 determines whether or not the acquired back pressure is greater than 100% of the set back pressure (step S708). When it is determined that the obtained back pressure is greater than 100% of the set back pressure (step S708: yes), the rotational speed of the screw 330 is reduced by a predetermined value (step S709: an example of the adjustment step). Then, the processing is performed again from step S705.

On the other hand, when it is determined that the obtained back pressure is not more than 100% of the set back pressure (step S708: no), the adjusting unit 716 determines that the back pressure is not more than 100% of the set back pressure and is out of the range of 50% to 100% of the set back pressure, and adjusts the rotation speed of the screw 330 by a predetermined value (step S710: an example of the adjusting step). Then, the processing is performed again from step S705.

Then, in step S707, when it is determined that the acquired back pressure is within the range of 50% to 100% of the set back pressure, the adjusting unit 716 stores the current rotation speed of the screw 330 in the setting information storage unit 711, and the process ends.

By performing the control, the reverse speed and the rotational speed, which are the appropriate back pressure at the end of the measurement process, can be set.

In the above processing steps, the case where the control of the reverse speed is performed from the beginning based on the parameter input by the user is described. The above-described processing steps are shown as an example of a control method of the injection molding machine, and are not limited to a method of performing the reverse speed control from the beginning. As a control method of the injection molding machine, for example, the control may be switched from the normal back pressure control to the reverse speed control. Therefore, next, a case of switching from the back pressure control to the reverse speed control will be described.

Fig. 8 is a flowchart showing a process of setting parameters when switching from back pressure control to reverse speed control in the measurement step in the control device 700 according to the present embodiment. In the example shown in fig. 8, the setting for back pressure control is performed.

First, the control unit 715 performs a molding process including a measurement step based on back pressure control (step S801).

The input processing unit 712 receives an input from the user via the operation device 750 to switch from the back pressure control to the reverse speed control (step S802).

The determination unit determines initial values of the set back pressure, the measurement position, the cooling time, the rotational speed, and the like based on the actual situation at the time of back pressure control (step S803). The setting back pressure is set based on, for example, a back pressure used for setting by back pressure control. The metering position is set to the same position as when the back pressure control is performed. The cooling time is also set to be the same time as when the back pressure control is performed. The initial value of the rotation speed is also set to be equal to the rotation speed at the time of back pressure control. The parameters are not limited to the method determined according to the actual situation at the time of back pressure control, and may be changed by the user.

Then, the determining unit 713 calculates the initial retraction speed of the screw 330 moving in the cylinder 310 based on the actual value of the measurement time and the measurement position (step S804).

The subsequent processing is performed in the same manner as in step S703 to step S710 in fig. 7, and the rotation speed is adjusted and then ended (step S805 to step S812).

The control device 700 according to the present embodiment has the above-described configuration, and can set an appropriate reverse speed and rotational speed, so that the burden on the user in setting can be reduced.

Further, the mold device 800 can be prevented from being filled with the molding material too little or too much, and thus the burden on the mold device 800 can be reduced.

The embodiments of the control device for an injection molding machine, the injection molding machine, and the control method according to the present application have been described above, but the present application is not limited to the above embodiments and the like. Various changes, modifications, substitutions, additions, deletions and combinations can be made within the scope described in the claims. These are, of course, within the technical scope of the present application.

The present application claims priority based on japanese patent application No. 2021-062316 filed on 3 months of 2021, 31, the entire contents of which are incorporated herein by reference.

Symbol description

10-injection molding machine, 300-injection device, 330-screw, 340-metering motor, 350-injection motor, 700-control device, 711-setting information storage section, 712-input processing section, 713-determination section, 714-acquisition section, 715-control section, 716-adjustment section.

Claims

1. A control device for an injection molding machine, comprising:

a determining unit that determines a retraction speed at which the screw is retracted, based on a metering position indicating a position of the screw in the cylinder after the movement for accumulating the molding material required for molding the molded article and a preset metering time, in a metering step for metering the molding material accumulated in the cylinder for injection molding;

An acquisition unit that acquires, in the metering step, a back pressure of the screw when the screw is controlled in accordance with the retraction speed and a preset rotation speed; and

And an adjusting unit that adjusts the rotation speed according to the back pressure.

2. The control device of an injection molding machine according to claim 1, wherein,

the acquisition unit acquires the back pressure at the end of the measurement process.

3. The control device of an injection molding machine according to claim 1, wherein,

the metering time used in determining the retreat speed by the determining portion is set according to a cooling time of a mold device filled with the molding material.

4. An injection molding machine, comprising:

5. A control method of an injection molding machine includes:

a determination step of determining a retraction speed of retracting the screw, based on a metering position indicating a position of the screw in the cylinder for determining an amount of molding material required for molding a molded article and a preset metering time, in a metering step of metering the molding material stored in the cylinder for injection molding;

an acquisition step of acquiring, in the metering step, a back pressure of the screw when the screw is controlled in accordance with the retraction speed and a preset rotation speed; and

And an adjustment step of adjusting the rotation speed according to the back pressure.