JP2023148762A - Controller of injection molding machine, injection molding machine, and control method of injection molding machine - Google Patents

Abstract

To provide a technique for reducing an impact that occurs when retreating an injection member in a pressure holding process.SOLUTION: Provided is a controller of an injection molding machine comprising: an injection member provided inside a cylinder for heating a molding material; and an injection driving source which fills the molding material into a molding machine by advancing the injection member. The controller has a limiting part which limits retreating speed of the injection member to a preset limited value or less in a pressure holding process of controlling a filling pressure which works from the injection member to the molding material. The limiting part, when the position of the injection member reaches a preset deceleration starting position during retreat of the injection member in the pressure holding process, controls the retreating speed of the injection member to a speed smaller than the limited value.SELECTED DRAWING: Figure 7

Description

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

An injection molding machine has a cylinder that heats the molding material, an injection member provided inside the cylinder, an injection drive source that moves the injection member forward to fill the inside of the mold device with the molding material, and an injection drive source. and a control device for controlling (see Patent Document 1). The control device performs the filling process and the pressure holding process in this order. The filling step is a step of filling the inside of the mold device with the molding material by controlling the injection drive source so that the actual value of the moving speed of the injection member becomes the set value. In the pressure holding process, the injection drive source is controlled so that the actual value of the filling pressure acting on the molding material from the injection member becomes the set value, thereby replenishing the shortage of molding material due to cooling shrinkage within the mold equipment. This is the process of

Switching from the filling process to the pressure holding process is also called V/P switching. After the V/P switching, if the actual value of the filling pressure is larger than the set value, the injection member is retreated so that the actual value of the filling pressure becomes smaller. Patent Document 1 states that by setting a limit value on the retraction speed of the injection member during the pressure holding process, it is possible to eliminate the adverse effect on the quality of the molded product due to the screw retracting at high speed during the pressure holding process. has been done.

Patent No. 3917459

By the way, a nozzle is provided at the tip of the cylinder. The nozzle injects the molding material heated in the cylinder into the mold device. If the temperature of at least one of the nozzle and the cylinder is too low, the viscosity of the molding material exceeds the viscosity suitable for the injection pressure, resulting in so-called nozzle clogging. Nozzle clogging is a phenomenon in which the molding material is not injected from the nozzle even when the filling process is started and the injection member is advanced.

When nozzle clogging occurs, after V/P switching, the actual value of the filling pressure is larger than the set value, and the deviation is large, so there is a risk that the injection member will be retreated to the retraction limit position of the movable range. . When the injection member is retracted to the retraction limit position, an impact is generated on the mechanical elements constituting the injection device, shortening the life of the mechanical elements.

An example of the mechanical element is a ball screw. The ball screw converts the rotational motion of the injection motor into linear motion of the injection member. A ball screw includes a screw shaft, a screw nut, and a ball that rolls between the screw shaft and the screw nut. When the screw nut reaches the stroke end of the screw shaft, the injection member reaches the retraction limit position, and the injection member stops retreating.

Note that the cause of the injection member being retracted to the retraction limit position is not limited to nozzle clogging. For example, a similar problem may occur if a molded product is improperly removed. If a molded product fails to be taken out, the filling process is started with the molded product still inside the mold device. Therefore, after the V/P switching, since the actual value of the filling pressure is larger than the set value and the deviation thereof is large, there is a possibility that the injection member will be retreated to the retraction limit position of the movable range.

One aspect of the present invention provides a technique for reducing the impact caused by retreating the injection member during the pressure holding process.

A control device for an injection molding machine according to one aspect of the present invention includes an injection member provided inside a cylinder that heats molding material, and filling the inside of a mold device with the molding material by advancing the injection member. A control device for an injection molding machine including an injection drive source. The control device includes a limiter that limits the retraction speed of the injection member to a preset limit value or less in a pressure holding step that controls the filling pressure applied to the molding material from the injection member. In the pressure holding step, when the position of the injection member reaches a predetermined deceleration start position while the injection member is retracting, the restriction portion sets the retraction speed of the injection member to be smaller than the limit value. Control the speed.

According to one aspect of the present invention, when the position of the injection member reaches a preset deceleration start position during retraction of the injection member in the pressure holding process, the retraction speed of the injection member is controlled to a speed smaller than a limit value. . As a result, even if the injection member is retracted to the maximum retraction position, the retraction speed of the injection member at that time is small and the impact is small. Therefore, the impact can be reduced.

FIG. 1 is a diagram illustrating a state of an injection molding machine according to an embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment during mold clamping. FIG. 3 is a diagram showing an example of the components of the control device in functional blocks. FIG. 4 is a diagram showing an example of a molding cycle process. FIG. 5 is a diagram showing an example of an injection control section. FIG. 6 is a diagram illustrating an example of a restriction section. FIG. 7 is a diagram showing an example of changes over time in screw speed, filling pressure, and screw position.

Embodiments of the present invention will be described below with reference to the drawings. Note that in each drawing, the same or corresponding configurations are denoted by the same reference numerals, and the description thereof may be omitted.

(Injection molding machine)
FIG. 1 is a diagram illustrating a state of an injection molding machine according to an embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment during mold clamping. In this 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 the horizontal direction, and the Z-axis direction represents the vertical direction. When the mold clamping device 100 is a horizontal type, the X-axis direction is the mold opening/closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side in the Y-axis direction is called the operation side, and the positive side in the Y-axis direction is called the counter-operation 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 ejector device 200 that ejects a molded product molded in the mold device 800, and a mold device 800 that ejects a molded product formed by the mold device 800. an injection device 300 that injects molding material into the mold, a moving device 400 that moves the injection device 300 forward and backward with respect to the mold device 800, a control device 700 that controls each component of the injection molding machine 10, and each of the injection molding machines 10. It has a frame 900 that supports the components. Frame 900 includes a mold clamping device frame 910 that supports mold clamping device 100 and an injection device frame 920 that supports injection device 300. The mold clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via a leveling adjuster 930. The control device 700 is arranged in the interior space of the injection device frame 920. Each component of the injection molding machine 10 will be explained 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 referred to as the front, and the moving direction of the movable platen 120 when the mold is opened (for example, the X-axis negative direction) is referred to as the rear. do.

The mold clamping device 100 performs mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold device 800. Mold device 800 includes a fixed 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 in the mold opening/closing direction relative to the fixed platen 110. has.

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

The movable platen 120 is arranged 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 installed on the mold clamping device frame 910. A movable mold 820 is attached to a surface of the movable platen 120 facing the fixed platen 110.

The moving mechanism 102 moves the movable platen 120 forward and backward relative to the fixed platen 110 to close the mold, increase the pressure, clamp the mold, depressurize the mold, and open the mold. The moving mechanism 102 includes a toggle support 130 arranged at a distance from the fixed platen 110, a tie bar 140 that connects the fixed platen 110 and the toggle support 130, and a movable platen 120 that moves the movable platen 120 in the mold opening/closing direction relative to the toggle support 130. a toggle mechanism 150 that operates the toggle mechanism 150, a mold clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the mold clamping motor 160 into linear motion, and a mold that adjusts the distance between the fixed platen 110 and the toggle support 130. It has a thickness adjustment mechanism 180.

The toggle support 130 is arranged at a distance from the fixed platen 110 and is placed on the mold clamping device frame 910 so as to be movable in the mold opening/closing direction. Note that the toggle support 130 may be arranged to be movable along a guide laid on the mold clamping device frame 910. The guide of the toggle support 130 may be the same as the guide 101 of the movable platen 120.

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

The tie bar 140 connects the fixed platen 110 and the toggle support 130 at a distance L in the mold opening/closing direction. A plurality of tie bars 140 (for example, four) may be used. The plurality of tie bars 140 are arranged parallel to the mold opening/closing direction, and expand according to the mold clamping force. At least one tie bar 140 may be provided with a tie bar distortion detector 141 that detects distortion of the tie bar 140. Tie bar distortion detector 141 sends a signal indicating the detection result to control device 700. The detection results of the tie bar distortion detector 141 are used for detecting mold clamping force and the like.

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

The toggle mechanism 150 is disposed between the movable platen 120 and the toggle support 130, and moves the movable platen 120 relative to the toggle support 130 in the mold opening/closing direction. The toggle mechanism 150 includes a crosshead 151 that moves in the mold opening/closing direction, and a pair of links that bend and expand as the crosshead 151 moves. Each of the pair of link groups includes a first link 152 and a second link 153 that are connected to each other with a pin or the like in a flexible manner. The first link 152 is swingably attached to the movable platen 120 with a pin or the like. The second link 153 is swingably attached to the toggle support 130 with a pin or the like. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 is moved forward and backward with respect to the toggle support 130, the first link 152 and the second link 153 are bent and extended, and the movable platen 120 is moved forward and backward with respect to the toggle support 130.

Note that the configuration of the toggle mechanism 150 is not limited to the configuration shown in FIGS. 1 and 2. For example, in FIGS. 1 and 2, the number of nodes in each link group is five, but it may be four, and one end of the third link 154 is connected to the nodes of the first link 152 and the second link 153. may be done.

The mold clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The mold clamping motor 160 moves the crosshead 151 forward and backward relative to the toggle support 130, thereby bending and extending the first link 152 and the second link 153, and moves the movable platen 120 forward and backward relative to the toggle support 130. The mold clamping motor 160 is directly connected to the motion conversion mechanism 170, but may also be connected to the motion conversion mechanism 170 via a belt, a pulley, or the like.

The motion conversion mechanism 170 converts the rotational motion of the mold clamping motor 160 into linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut that is threaded onto the screw shaft. A ball or roller 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 depressurizing process, a mold opening process, etc. under the control of the control device 700.

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

Note that the crosshead position detector that detects the position of the crosshead 151 and the crosshead movement speed detector that detects the moving speed of the crosshead 151 are not limited to the mold clamping motor encoder 161, but general ones can be used. can. Furthermore, the movable platen position detector that detects the position of the movable platen 120 and the movable platen movement speed detector that detects the moving speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, but may be general ones. can.

In the pressure increasing process, the mold clamping motor 160 is further driven to further advance the crosshead 151 from the mold closing completion position to the mold clamping position, thereby generating mold 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 process, the mold clamping force generated in the pressure increasing process is maintained. In the mold clamping process, a cavity space 801 (see FIG. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with liquid molding material. A molded article is obtained by solidifying the filled molding material.

The number of cavity spaces 801 may be one or more. In the latter case, multiple molded articles can be obtained simultaneously. An insert material may be placed in a part of the cavity space 801, and another part of the cavity space 801 may be filled with a molding material. A molded product in which the insert material and the molding material are integrated can be obtained.

In the depressurization step, the mold clamping motor 160 is driven to move the crosshead 151 back from the mold clamping position to the mold opening start position, thereby retracting the movable platen 120 and reducing the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

In the mold opening process, the movable platen 120 is moved backward by driving the mold clamping motor 160 to move the crosshead 151 backward from the mold opening start position to the mold opening completion position at a set movement speed, and the movable mold 820 is moved between the fixed metal molds and the mold opening process. Separate from mold 810. Thereafter, the ejector device 200 ejects the molded product from the movable mold 820.

Setting conditions in the mold closing process, pressure increasing process, and mold clamping process are collectively set as a series of setting conditions. For example, the moving speed and position of the crosshead 151 (including the mold closing start position, the movement speed switching position, the mold closing completion position, and the mold clamping position) and the mold clamping force in the mold closing process and the pressure increasing process are determined by a series of setting conditions. are set all together as . The mold closing start position, the moving speed switching position, the mold closing completion position, and the mold closing position are arranged in this order from the rear side toward the front, and represent the starting point and ending point of the section in which the moving speed is set. A moving speed is set for each section. There may be one or more moving speed switching positions. The moving speed switching position does not need to be set. Only one of the mold clamping position and mold clamping force may be set.

Setting conditions in the depressurization process and mold opening process are similarly set. For example, the moving speed and position (mold opening start position, moving speed switching position, and mold opening completion position) of the crosshead 151 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 toward the rear, 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. There may be one or more moving speed switching positions. The moving speed switching position does not need to be set. The mold opening start position and the mold closing completion position may be the same position. Further, the mold opening completion position and the mold closing start position may be the same position.

Note that instead of the moving speed, position, etc. of the crosshead 151, the moving speed, position, etc. of the movable platen 120 may be set. Moreover, the mold clamping force may be set instead of the position of the crosshead 151 (for example, mold clamping position) or the position of the movable platen 120.

By the way, the toggle mechanism 150 amplifies the driving force of the mold clamping motor 160 and transmits it to the movable platen 120. The amplification factor is also called the toggle factor. The toggle magnification changes depending on the angle θ formed by the first link 152 and the second link 153 (hereinafter also referred to as “link angle θ”). The link angle θ is determined from the position of the crosshead 151. When the link angle θ is 180°, the toggle magnification is maximum.

When the thickness of the mold device 800 changes due to replacement of the mold device 800 or a change in the temperature of the mold device 800, the mold thickness is adjusted so that a predetermined mold clamping force is obtained during mold clamping. In the mold thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle support 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the time of mold touch when the movable mold 820 touches the fixed mold 810. Adjust.

The mold clamping device 100 has a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the mold thickness by adjusting the distance L between the fixed platen 110 and the toggle support 130. The mold thickness adjustment is performed, for example, between the end of a molding cycle and the start of the next molding cycle. The mold thickness adjustment mechanism 180 is, for example, screwed into a screw shaft 181 formed at the rear end of the tie bar 140, a screw nut 182 that is rotatably but not retractably held on the toggle support 130, and screwed onto the screw shaft 181. It has a mold thickness adjustment motor 183 that rotates a screw nut 182.

A screw shaft 181 and a screw nut 182 are provided for each tie bar 140. The rotational driving force of the mold thickness adjustment motor 183 may be transmitted to the plurality of threaded nuts 182 via the rotational driving force transmission section 185. A plurality of screw nuts 182 can be rotated synchronously. Note that by changing the transmission path of the rotational driving force transmission section 185, it is also possible to rotate the plurality of screw nuts 182 individually.

The rotational driving force transmission section 185 is composed of, for example, a gear. In this case, a driven gear is formed on the outer periphery of each screw nut 182, a driving gear is attached to the output shaft of the mold thickness adjustment motor 183, and an intermediate gear that meshes with the plurality of driven gears and the driving gear is located at the center of the toggle support 130. is held rotatably. Note that the rotational driving force transmission section 185 may be configured with a belt, a pulley, or the like instead of a gear.

The operation of mold thickness adjustment mechanism 180 is controlled by control device 700. The control device 700 drives the mold thickness adjustment motor 183 to rotate the screw nut 182. As a result, the position of toggle support 130 with respect to tie bar 140 is adjusted, and the distance L between fixed platen 110 and toggle support 130 is adjusted. Note that a plurality of mold thickness adjustment mechanisms may be used in combination.

The distance L is detected using a mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the rotation amount and rotation direction of the mold thickness adjustment motor 183 and sends a signal indicating the detection result to the control device 700. The detection results of the mold thickness adjustment motor encoder 184 are used for monitoring and controlling the position and interval L of the toggle support 130. Note that the toggle support position detector that detects the position of the toggle support 130 and the interval detector that detects the interval L are not limited to the mold thickness adjustment motor encoder 184, and general ones can be used.

The mold clamping device 100 may include a mold temperature regulator that adjusts the temperature of the mold device 800. The mold device 800 has a temperature control medium flow path therein. The mold temperature regulator adjusts the temperature of the mold device 800 by adjusting the temperature of the temperature regulating medium supplied to the flow path of the mold device 800.

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

Although the mold clamping device 100 of this embodiment has a mold clamping motor 160 as a drive unit, it may have a hydraulic cylinder instead of the mold clamping motor 160. Moreover, the mold clamping device 100 may have a linear motor for opening and closing the mold, and may have an electromagnet for mold clamping.

(Ejector device)
In the description of the ejector device 200, similarly to the description of the mold clamping device 100, the moving direction of the movable platen 120 when closing the mold (for example, The explanation will be made assuming that the X-axis negative direction) is the rear direction.

Ejector device 200 is attached to movable platen 120 and moves forward and backward together with movable platen 120. Ejector device 200 includes an ejector rod 210 that ejects a molded product from mold device 800, and a drive mechanism 220 that moves ejector rod 210 in the moving direction of movable platen 120 (X-axis direction).

The ejector rod 210 is arranged in a through hole of the movable platen 120 so as to be able to move forward and backward. The front end of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The front end of the ejector rod 210 may or may not be connected to the ejector plate 826.

The drive mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts the rotational motion of the ejector motor into linear motion of the ejector rod 210. The motion conversion mechanism includes a screw shaft and a screw nut that is threaded onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

The ejector device 200 performs an ejection process under the control of the control device 700. In the ejecting step, the ejector rod 210 is advanced from the standby position to the ejecting position at a set movement speed, thereby advancing the ejector plate 826 and ejecting the molded product. Thereafter, the ejector motor is driven to move the ejector rod 210 backward at a set movement speed, and the ejector plate 826 is moved back to its original standby position.

The position and moving speed of the ejector rod 210 are detected using, for example, an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and sends a signal indicating the detection result to the control device 700. Note that the ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod movement speed detector that detects the moving speed of the ejector rod 210 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 ejector device 200, the direction of movement of the screw 330 during filling (for example, the negative direction of the X axis) is referred to as the front, and the direction of movement of the screw 330 during metering is (For example, the X-axis positive direction) will be explained as being backward.

The injection device 300 is installed on a slide base 301, and the slide base 301 is arranged to be movable forward and backward relative to the injection device frame 920. The injection device 300 is arranged to be movable forward and backward relative to the mold device 800. The injection device 300 touches the mold device 800 and fills the cavity space 801 in the mold device 800 with the molding material. The injection device 300 includes, for example, a cylinder 310 that heats the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 that is rotatably disposed in the cylinder 310 so as to be able to move forward and backward, and rotate the screw 330. an injection motor 350 that moves the screw 330 forward and backward, and a load detector 360 that detects the load transmitted between the injection motor 350 and the screw 330.

The cylinder 310 heats the molding material supplied therein from the supply port 311 . The molding material includes, for example, resin. The molding material is formed into a pellet shape, for example, and is supplied to the supply port 311 in a solid state. The supply port 311 is formed at the rear of the cylinder 310 . A cooler 312 such as a water-cooled cylinder is provided on the outer periphery of the rear portion of the cylinder 310 . A first heater 313 such as a band heater and a first 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 zones in the axial direction (for example, the X-axis direction) of the cylinder 310. A first heater 313 and a first 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 control device 700 controls the first heater 313 so that the temperature detected by the first temperature detector 314 becomes the set temperature.

The nozzle 320 is provided at the front end of the cylinder 310 and is pressed against the mold device 800. A second heater 323 and a second temperature detector 324 are provided on the outer periphery of the nozzle 320. The control device 700 controls the second heater 323 so that the detected temperature of the nozzle 320 becomes the set temperature.

The screw 330 is arranged within the cylinder 310 so as to be rotatable and movable back and forth. When the screw 330 is rotated, the molding material is sent forward along the spiral groove of the screw 330. The molding material is gradually melted by heat from the cylinder 310 while being sent forward. As the liquid molding material is sent forward of the screw 330 and accumulated at the front of the cylinder 310, the screw 330 is retracted. Thereafter, when the screw 330 is moved forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled into the mold device 800.

A backflow prevention ring 331 is attached to the front of the screw 330 so that it can move forward and backward as a backflow prevention valve that prevents 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 backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and is moved relative to the screw 330 to a closed position (see FIG. 2) where it 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, when the screw 330 is rotated, the backflow prevention ring 331 is pushed forward by the pressure of the molding material sent forward along the spiral groove of the screw 330, and is moved to an open position where the flow path of the molding material is opened. (see FIG. 1) relative to the screw 330. As a result, the molding material is sent to the front of the screw 330.

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

Note that the injection device 300 may include a drive source that moves the backflow prevention ring 331 forward and backward relative to the screw 330 between an open position and a closed position.

Metering motor 340 rotates 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. A motion conversion mechanism or the like that converts the rotational motion of the injection motor 350 into linear motion of the screw 330 is provided between the injection motor 350 and the screw 330. The motion conversion mechanism includes, for example, a screw shaft and a screw nut that is threaded onto the screw shaft. A ball, roller, etc. may be provided between the screw shaft and the screw nut. The drive source for advancing and retracting the screw 330 is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder.

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

Load detector 360 sends a detected load signal to control device 700. The load detected by the load detector 360 is converted into the pressure that acts between the screw 330 and the molding material, and includes the pressure that the screw 330 receives from the molding material, the back pressure on the screw 330, and the pressure that acts on the molding material from the screw 330. Used for controlling and monitoring pressure, etc.

Note that the pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and any general pressure detector can be used. For example, a nozzle pressure sensor or an internal mold pressure sensor may be used. A nozzle pressure sensor is installed on the nozzle 320. The mold internal pressure sensor is installed inside the mold device 800.

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

In the metering process, the screw 330 is rotated at a set rotation speed by driving the metering motor 340, and the molding material is sent forward along the spiral groove of the screw 330. Along with this, the molding material is gradually melted. As the liquid molding material is sent forward of the screw 330 and accumulated at the front of the cylinder 310, the screw 330 is retracted. The rotational speed of the screw 330 is detected using, for example, a metering motor encoder 341. Measuring motor encoder 341 detects the rotation of metering motor 340 and sends a signal indicating the detection result to control device 700. Note that 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 type 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, for example, a load detector 360. 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 metering process is completed.

The position and rotational speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, a measurement start position, a rotational speed switching position, and a measurement completion position are set. These positions are lined up in this order from the front to the rear, and represent the start and end points of the section in which the rotational speed is set. The rotation speed is set for each section. The number of rotational speed switching positions may be one or more. The rotational speed switching position does not need to be set. Further, 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 moving speed, and the liquid molding material accumulated in front of the screw 330 is filled into the cavity space 801 in the mold device 800. The position and moving speed of the screw 330 are detected using, for example, an injection motor encoder 351. Injection motor encoder 351 detects rotation of injection motor 350 and sends a signal indicating the detection result to control device 700. When the position of the screw 330 reaches the set position, the filling process is switched to the pressure holding process (so-called V/P switching). The position where V/P switching is performed is also called the V/P switching position. The set moving speed of the screw 330 may be changed depending on the position of the screw 330, time, etc.

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 referred to as an "injection start position"), a moving speed switching position, and a V/P switching position are set. These positions are lined up in this order from the rear to the front, and represent the start and end points of the section in which the moving speed is set. A moving speed is set for each section. There may be one or more moving speed switching positions. The moving speed switching position does not need 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 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 is advanced at the set travel speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is moved forward at a moving speed slower than the set moving speed so that the pressure of the screw 330 becomes equal to or lower than the set pressure for the purpose of protecting the mold.

In addition, after the position of the screw 330 reaches the V/P switching position in the filling process, the screw 330 may be temporarily stopped at the V/P switching position, and then the V/P switching may be performed. Immediately before the V/P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a very slow speed. Further, the screw position detector that detects the position of the screw 330 and the screw movement speed detector that detects the moving speed of the screw 330 are not limited to the injection motor encoder 351, and general ones can be used.

In the pressure holding 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, and the pressure inside the cylinder 310 is maintained. The remaining molding material is pushed toward the mold apparatus 800. Insufficient molding material due to cooling shrinkage within the mold device 800 can be replenished. The holding pressure is detected using the load detector 360, for example. The set value of the holding pressure may be changed depending on the elapsed time from the start of the pressure holding process. A plurality of holding pressures and a plurality of holding times for holding the holding pressure in the pressure holding step may be set, and may be set all at once as a series of setting conditions.

In the pressure holding process, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and when the pressure holding 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 backflow of the molding material from the cavity space 801 is prevented. After the pressure holding process, a cooling process is started. In the cooling process, the molding material within the cavity space 801 is solidified. A metering step may be performed during the cooling step to reduce molding cycle time.

Although the injection device 300 of this embodiment is of an in-line screw type, it may also be of a pre-plastic type. A pre-plastic injection device supplies a molding material melted in a plasticizing cylinder to an injection cylinder, and injects the molding material from the injection cylinder into a mold device. Inside the plasticizing cylinder, a screw is arranged so as to be rotatable but not moveable, or a screw is arranged so as to be rotatable and move back and forth. On the other hand, a plunger is arranged within the injection cylinder so that it can move forward and backward.

Moreover, although the injection device 300 of this embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, it 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 vertical or horizontal. Similarly, the mold clamping device combined with the horizontal injection device 300 may be horizontal or vertical.

(mobile device)
In the description of the moving device 400, similarly to the description of the injection device 300, the direction of movement of the screw 330 during filling (for example, the negative direction of the X-axis) is referred to as the front, and the direction of movement of the screw 330 during metering (for example, the positive direction of the X-axis) is referred to as the front. will be explained as backward.

The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. Furthermore, 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.

Hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectionally rotatable pump, and by switching the rotation direction of the motor 420, the hydraulic pump 410 sucks in hydraulic fluid (for example, oil) from one of the first port 411 and the second port 412 and discharges it from the other. to generate hydraulic pressure. Note that 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.

Motor 420 operates hydraulic pump 410. Motor 420 drives hydraulic pump 410 in a rotational direction and rotational torque according to a control signal from control device 700. 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. The cylinder body 431 is fixed 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 fixed 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 injection device 300 is pushed forward by the hydraulic fluid discharged from the first port 411 being supplied to the front chamber 435 via the first flow path 401. The injection device 300 is advanced and the nozzle 320 is pressed against the fixed 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 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 second port 412 of the hydraulic pump 410 via the second flow path 402 . The injection device 300 is pushed rearward by the hydraulic fluid discharged from the second port 412 being supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402. The injection device 300 is moved back, and the nozzle 320 is separated from the fixed mold 810.

Note that in this embodiment, the moving device 400 includes a hydraulic cylinder 430, but the present invention is not limited thereto. For example, instead of the hydraulic cylinder 430, an electric motor and a motion conversion mechanism that converts the rotational motion of the electric motor into linear motion of the injection device 300 may be used.

(Control device)
The control device 700 is composed of, for example, a computer, and includes 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. Furthermore, the control device 700 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 controls the molded product by repeatedly performing a measuring process, a mold closing process, a pressurizing process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a depressurizing process, a mold opening process, an ejecting process, etc. Manufacture repeatedly. A series of operations for obtaining a molded product, for example, from the start of a metering process to the start of the next metering process, is also called a "shot" or a "molding cycle." The time required for one shot is also called "molding cycle time" or "cycle time."

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

Note that 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 during the cooling step of the previous molding cycle, or during the clamping step. In this case, the mold closing step may be performed at the beginning of the molding cycle. Also, the filling process may be started during the mold closing process. Also, the ejection process may be started during the mold opening process. If an on-off valve is provided to open and close the flow path of the nozzle 320, the mold opening process may be started during the metering process. This is because even if the mold opening process is started during the metering process, if the on-off valve closes the flow path of the nozzle 320, the molding material will not leak from the nozzle 320.

In addition, one molding cycle includes processes other than the measuring process, mold closing process, pressure increase process, mold clamping process, filling process, pressure holding process, cooling process, depressurization process, mold opening process, and ejection process. It's okay.

For example, after the pressure holding process is completed and before the measurement process is started, a pre-measurement suckback process may be performed in which the screw 330 is retreated to a preset measurement start position. The pressure of the molding material accumulated in front of the screw 330 before the start of the metering process can be reduced, and rapid retraction of the screw 330 at the start of the metering process can be prevented.

Further, after the completion of the measurement process and before the start of the filling process, a post-measurement suck-back process may be performed in which the screw 330 is retreated to a preset filling start position (also referred to as "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 operating device 750 that accepts input operations by a user and a display device 760 that displays a screen. The operating device 750 and the display device 760 may be configured with a touch panel 770, for example, and may be integrated. The touch panel 770 serving as the 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, for example. Further, the screen of the touch panel 770 may display, for example, an operation unit such as a button or an input field that accepts an input operation by the user. The touch panel 770 serving as the operating 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, the user can, for example, configure the injection molding machine 10 (including inputting setting values) by operating the operation unit provided on the screen while checking the information displayed on the screen. can. Further, by the user operating an operating section provided on the screen, it is possible to cause the injection molding machine 10 to perform an operation corresponding to the operating section. Note that 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. Further, the operation of the injection molding machine 10 may be switching of screens displayed on a touch panel 770 serving as the display device 760.

Note that although the operating device 750 and the display device 760 of this embodiment have been described as being integrated as the touch panel 770, they may be provided independently. Further, 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).

(Details of control device)
Next, an example of the components of the control device 700 will be described with reference to FIG. 3. Note that each functional block illustrated in FIG. 3 is conceptual and does not necessarily need to be physically configured as illustrated. It is possible to configure all or part of each functional block by functionally or physically distributing and integrating it in arbitrary units. All or any part of each processing function performed by each functional block can be realized by a program executed by a CPU, or can be realized by hardware using wired logic.

As shown in FIG. 3, the control device 700 includes, for example, a mold clamping control section 711, an ejector control section 712, an injection control section 713, and a metering control section 714. The mold clamping control unit 711 controls the mold clamping device 100 and performs a mold closing process, a pressure increasing process, a mold clamping process, a depressurizing process, and a mold opening process shown in FIG. The ejector control unit 712 controls the ejector device 200 and performs the ejecting process. The injection control unit 713 controls the injection drive source of the injection device 300 and performs an injection process. The injection drive source is, for example, the injection motor 350, but may also be a hydraulic cylinder or the like. The injection process includes a filling process and a pressure holding process. The injection process is performed during the mold clamping process. The metering control unit 714 controls the metering drive source of the injection device 300 and carries out a metering process. The metering drive source is, for example, the metering motor 340, but may also be a hydraulic pump or the like. The metering process is performed during the cooling process.

The filling process is a process of controlling the injection drive source so that the actual value of the moving speed of the injection member provided inside the cylinder 310 becomes the set value. The filling step is a step of moving the injection member forward to fill the inside of the mold device 800 with the liquid molding material accumulated in front of the injection member. The injection member is, for example, a screw 330 (see FIGS. 1 and 2), but may also be a plunger.

The moving speed of the injection member is detected using a speed detector. The speed detector is, for example, the injection motor encoder 351. In the filling process, as the injection member moves forward, the pressure that acts on the molding material from the injection member (hereinafter also referred to as "filling pressure") increases. The filling step may include a step of temporarily stopping the injection member or a step of retracting the injection member immediately before the pressure holding step.

The pressure holding process is a process of controlling the injection drive source so that the actual value of the filling pressure becomes the set value. The holding pressure step is a step of pushing the injection member forward to replenish the molding material that is insufficient due to cooling shrinkage within the mold device 800. Filling pressure is detected using a pressure detector such as load detector 360. A nozzle pressure sensor or a mold internal pressure sensor may be used as the pressure detector.

The pressure holding process is controlled by the injection control section 713. As shown in FIG. 5, the injection control section 713 includes, for example, a speed setting section 713a and a command creation section 713b. The speed setting unit 713a creates a set value for the speed of the injection member based on the deviation between the set value of the filling pressure and the actual value. The command creation unit 713b creates a command (for example, a current command) for the injection drive source based on the deviation between the set value and the actual value of the speed of the injection member. The injection drive source is, for example, the injection motor 350. The injection drive source is driven according to the command created by the command creation section 713b.

The speed setting unit 713a creates a set value for the speed of the injection member so that the actual value of the filling pressure becomes the set value. The actual value of the filling pressure is obtained using a pressure detector such as the load detector 360. The speed setting unit 713a creates a set value for the speed of the injection member by, for example, PID calculation or PI calculation.

The command creation unit 713b creates a command to the injection drive source so that the actual value of the speed of the injection member becomes the set value. The actual value of the speed of the injection member is obtained using a speed detector such as the injection motor encoder 351. The command creation unit 713b creates commands for the injection drive source by, for example, PID calculation or PI calculation.

The injection control section 713 has a restriction section 713c. The restricting portion 713c limits the retraction speed of the injection member to a preset limit value V1 or less during the retraction of the injection member in the pressure holding process. In the pressure holding step, it is possible to eliminate the adverse effect on the quality of the molded product due to the injection member retreating at high speed. The limit value V1 is set so as to eliminate the adverse effect on the quality of the molded product due to the injection member retreating at high speed.

For example, as shown in FIG. 6, the limiting unit 713c compares the set value (>0) of the backward speed created by the speed setting unit 713a with the limiting value V1 (V1>0). The limiter 713c sets the minimum value between the set value (>0) of the backward speed created by the speed setting unit 713a and the limit value V1 (V1>0) (including the case where the set value and the limit value V1 are equal). It is output to the command generation unit 713b as a set value of the backward speed. The command creation unit 713b creates a command for the injection drive source based on the deviation between the set value and the actual value output by the restriction unit 713c.

Therefore, as shown in FIG. 6, the restriction part 713c monitors the position of the injection member while the injection member is retracting in the pressure holding process, corrects the set value of the retraction speed according to the position of the injection member, and corrects the The correction unit 713d outputs the set value to the command creation unit 713b. The correction unit 713d uses a position detector such as the injection motor encoder 351 to obtain the position of the injection member.

In the pressure holding process, when the position of the injection member reaches a preset deceleration start position A2 (see FIG. 7) while the injection member is retracting, the correction unit 713d changes the set value of the retraction speed of the injection member to a limit value. Correct the speed to be smaller than V1. The deceleration start position A2 is set behind the filling start position A3 and ahead of the retraction limit position A0. The filling start position A3 is the position at the start of the filling process.

Thereby, in the pressure holding step, when the position of the injection member reaches the deceleration start position A2 while the injection member is retracting, the retraction speed of the injection member becomes smaller than the limit value V1. Therefore, even if the injection member is retracted to the retraction limit position A0, the retraction speed at that time is small and the impact is small. Therefore, the impact can be reduced. Further, until the position of the injection member reaches the deceleration start position A2, the retraction speed can be controlled to the limit value V1, and the filling pressure can be quickly reduced.

In the pressure holding process, when the position of the injection member reaches a preset stop position A1 while the injection member is retracting, the correction unit 713d corrects the set value of the retraction speed of the injection member to zero. The stop position A1 is set behind the deceleration start position A2 and ahead of the reverse limit position A0. Thereby, in the pressure holding process, when the position of the injection member reaches the stop position A1 while the injection member is retreating, the injection member is stopped. Therefore, the position of the injection member can be prevented from being retracted to the maximum retraction position A0, and the impact caused by the position of the injection member being retracted to the maximum retraction position A0 can be eliminated.

The correction unit 713d gradually corrects the backward speed of the injection member to a smaller speed as the position of the injection member approaches the stop position A1 from the deceleration start position A2. As a result, as the position of the injection member approaches the stop position A1 from the deceleration start position A2, the retraction speed of the injection member gradually decreases. It is possible to gently reduce the backward speed and suppress the occurrence of vibration.

Next, with reference to FIG. 7, an example of changes over time in screw speed, filling pressure, and screw position will be described. In FIG. 7, the screw speed is an example of the speed of the injection member, and the screw position is an example of the position of the injection member. The screw position is expressed as a distance from the forward limit position of the movable range of the screw 330. As the screw position retreats from the forward limit position, the distance representing the screw position increases.

In FIG. 7, t0 is the start time of the filling process, t1 is the time of V/P switching, t2 is the time when the actual value of the screw speed (backward speed) reaches the limit value V1, and t3 is the time when the screw position decelerates. t4 represents the time when the screw position reaches the stop position A1, and t5 represents the end time of the pressure holding process.

When the filling process is started at time t0, the screw position advances at a set speed. As a result, the filling pressure increases. If the nozzle is clogged or the molded product is not ejected properly, the filling pressure will increase rapidly because almost no molding material will be injected even if the screw position moves forward.

Thereafter, when the screw position reaches the V/P switching position at time t1, the pressure holding process is started. In the pressure holding step, the screw position is controlled so that the actual value of the filling pressure becomes the set value P1. When nozzle clogging occurs, the actual value of the filling pressure is larger than the set value P1, and the deviation thereof is large.

Therefore, when nozzle clogging occurs, the screw position is moved back after time t1 so that the actual value of the filling pressure becomes smaller. Then, the screw speed (specifically, the retraction speed) gradually increases, and the retraction speed reaches the limit value V1 at time t2.

The limiter 713c limits the backward speed to the limit value V1 so that the backward speed does not exceed the limit value V1. Thereafter, at time t3, when the screw position reaches the deceleration start position A2, the limiter 713c controls the retraction speed to a speed smaller than the limit value V1. As a result, even if the screw position is retracted to the retraction limit position A0, the retraction speed at that time is small and the impact is small. Therefore, the impact can be reduced. Further, until the screw position reaches the deceleration start position A2, the retraction speed can be controlled to the limit value V1, and the filling pressure can be quickly reduced.

Thereafter, at time t4, when the screw position reaches the stop position A1, the restricting portion 713c stops the screw 330. The stop position A1 is set ahead of the reverse limit position A0. Therefore, it is possible to prevent the screw position from being retracted to the maximum retraction position A0, and it is possible to eliminate the impact caused by the screw position being retracted to the maximum retraction position A0.

As shown in FIG. 7, from time t3 to time t4, as the screw position approaches the stop position A1 from the deceleration start position A2, the limiter 713c gradually controls the retraction speed to a lower speed. It is possible to gently reduce the backward speed and suppress the occurrence of vibration.

Although the embodiments of the injection molding machine control device, the injection molding machine, and the injection molding machine control method 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 naturally fall within the technical scope of the present invention.

10 Injection molding machine 310 Cylinder 330 Screw (injection member)
350 Injection motor (injection drive source)
700 Control device 713c Restriction section 800 Mold device

Claims (6)

A control device for an injection molding machine, comprising: an injection member provided inside a cylinder that heats molding material; and an injection drive source that moves the injection member forward to fill the inside of a mold device with the molding material. hand,
In the pressure holding step of controlling the filling pressure acting on the molding material from the injection member, the method includes a restriction portion that limits the retraction speed of the injection member to a preset limit value or less,
In the pressure holding step, when the position of the injection member reaches a predetermined deceleration start position while the injection member is retracting, the restriction portion sets the retraction speed of the injection member to be smaller than the limit value. A control device for an injection molding machine that controls speed. In the pressure holding step, when the position of the injection member reaches a preset stop position while the injection member is retreating, the restriction portion stops the injection member at the stop position;
The control device for an injection molding machine according to claim 1, wherein the stop position is set behind the deceleration start position and ahead of a retraction limit position of a movable range of the injection member. The control of the injection molding machine according to claim 2, wherein the restriction section controls the retraction speed of the injection member to a gradually smaller speed as the position of the injection member approaches the stop position from the deceleration start position. Device. a speed setting unit that creates a set value for the speed of the injection member based on the deviation between the actual value and the set value of the filling pressure; a command creation unit that creates a command;
The limiting section is configured to set the minimum value between the set value of the retreat speed created by the speed setting section and the limit value as the set value of the retreat speed during the retreat of the injection member in the pressure holding step. The control device for an injection molding machine according to any one of claims 1 to 3, wherein the control device outputs the command to a command creation section. An injection molding machine comprising: the control device according to claim 1; the injection member; and the injection drive source. A method for controlling an injection molding machine comprising: an injection member provided inside a cylinder that heats molding material; and an injection drive source that advances the injection member to fill the inside of a mold device with the molding material. hand,
In the pressure holding step of controlling the injection drive source so that the actual value of the filling pressure acting on the molding material from the injection member becomes a set value, the retraction speed of the injection member is limited to a preset limit value or less. The process of
In the pressure holding step, when the position of the injection member reaches a preset deceleration start position while the injection member is retracting, the retraction speed of the injection member is reduced to a speed smaller than the limit value. and,
A method for controlling an injection molding machine, comprising:

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