JP2018144398A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine capable of enhancing surface accuracy of a molding to be compression-molded.SOLUTION: An injection molding machine is provided with a controller for controlling the advance and the retraction of a movable member used for a compression of a molding material filled in a cavity space of a mold device. After the controller controls the compression of the molding material by controlling the advance of the movable member, it controls a primary depressurization for decreasing the pressure, in a prescribed pattern, of the molding molded by the compression, and a secondary depressurization for retracting the movable member to a prescribed position after the primary depressurization to further decrease the pressure of the mold.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an injection molding machine.

  The injection molding machine described in Patent Document 1 compresses the resin in the cavity by moving the ejector plate of the mold by driving the ejector shaft.

JP 2014-237216 A

  Conventionally, the residual stress remaining in a molded product to be compression molded is large, and the surface accuracy of the molded product is poor.

  This invention is made | formed in view of the said subject, Comprising: It aims at provision of the injection molding machine which can improve the surface precision of the molded article compression-molded.

In order to solve the above problems, according to one aspect of the present invention,
A control device for controlling the advance and retreat of the movable member used for compressing the molding material filled in the cavity space of the mold device;
The controller controls the compression of the molding material by controlling the advance of the movable member, and then performs primary depressurization to lower the pressure of the molded product molded by the compression in a predetermined pattern, An injection molding machine is provided that controls secondary depressurization that lowers the pressure of the molded product by retracting the movable member to a predetermined position after the second depressurization.

  According to one aspect of the present invention, there is provided an injection molding machine that can improve the surface accuracy of a molded article to be compression molded.

It is a figure which shows the state at the time of mold opening completion of the injection molding machine by one Embodiment. It is a figure which shows the state at the time of the mold clamping of the injection molding machine by one Embodiment. FIG. 3 is a partially enlarged view of FIG. 2 showing a state where an ejector rod is in a compression standby position. It is a figure which shows the state which the ejector rod advanced from the compression standby position shown in FIG. 3 to a compression position. It is a figure which shows the state which the ejector rod retracted | retreated from the compression position shown in FIG. 4 to the compression standby position. It is a figure which shows the state which the ejector rod advanced from the compression standby position shown in FIG. 5 to the protrusion position. It is a figure which compares the depressurization pattern of the compression molded product by an Example, and the depressurization pattern of the compression molded product by a comparative example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof will be omitted.

(Injection molding machine)
FIG. 1 is a diagram illustrating a state when mold opening of an injection molding machine according to an embodiment is completed. FIG. 2 is a diagram illustrating a state during mold clamping of the injection molding machine according to the embodiment. As shown in FIGS. 1 to 2, the injection molding machine includes a mold clamping device 100, an ejector device 200, an injection device 300, a moving device 400, and a control device 700. Hereinafter, each component of the injection molding machine will be described.

(Clamping device)
In the description of the mold clamping device 100, the moving direction of the movable platen 120 when the mold is closed (right direction in FIGS. 1 and 2) is the front, and the moving direction of the movable platen 120 when the mold is opened (left in FIGS. 1 and 2). (Direction) will be described as the rear.

  The mold clamping apparatus 100 performs mold closing, mold clamping, and mold opening of the mold apparatus 10. The mold clamping device 100 is, for example, a horizontal mold, and the mold opening / closing direction is the horizontal direction. The mold clamping device 100 includes a fixed platen 110, a movable platen 120, a toggle support 130, a tie bar 140, a toggle mechanism 150, a mold clamping motor 160, a motion converting mechanism 170, and a mold thickness adjusting mechanism 180.

  The fixed platen 110 is fixed to the frame Fr. The fixed mold 11 is attached to the surface of the fixed platen 110 facing the movable platen 120.

  The movable platen 120 is movable in the mold opening / closing direction with respect to the frame Fr. A guide 101 for guiding the movable platen 120 is laid on the frame Fr. The movable platen 120 is attached to the surface of the movable platen 120 facing the fixed platen 110.

  By moving the movable platen 120 forward and backward with respect to the fixed platen 110, mold closing, mold clamping, and mold opening are performed. The fixed mold 11 and the movable platen 120 constitute a mold apparatus 10.

  The toggle support 130 is connected to the fixed platen 110 at an interval, and is placed on the frame Fr so as to be movable in the mold opening / closing direction. The toggle support 130 may be movable along a guide laid on the frame Fr. 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 frame Fr, and the toggle support 130 is movable in the mold opening / closing direction with respect to the frame Fr. However, the toggle support 130 is fixed to the frame Fr and fixed to the fixed platen. 110 may be movable in the mold opening / closing direction with respect to the frame Fr.

  The tie bar 140 connects the fixed platen 110 and the toggle support 130 with an interval L in the mold opening / closing direction. A plurality of tie bars 140 may be used. Each tie bar 140 is parallel to the mold opening / closing direction and extends according to the mold clamping force. At least one tie bar 140 is provided with a tie bar distortion detector 141 that detects distortion of the tie bar 140. The tie bar distortion detector 141 sends a signal indicating the detection result to the control device 700. The detection result of the tie bar distortion detector 141 is used for detecting the clamping force.

  In this embodiment, the tie bar strain detector 141 is used as a mold clamping force detector for detecting the mold clamping force, but the present invention is not limited to this. The mold clamping force detector is not limited to the strain gauge type, and may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, and 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 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 cross head 151, a pair of links, and the like. Each link group includes a first link 152 and a second link 153 that are connected to each other by a pin or the like. The first link 152 is swingably attached to the movable platen 120 with a pin or the like, and 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 the third link 154. When the crosshead 151 is moved back and forth 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 back and forth relative 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 four may be used, and one end of the third link 154 is coupled to the node between the first link 152 and the second link 153. May be.

  The mold clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The mold clamping motor 160 causes the first link 152 and the second link 153 to bend and extend by advancing and retracting the cross head 151 relative to the toggle support 130, and advances and retracts the movable platen 120 relative to the toggle support 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, a pulley, or the like.

  The motion conversion mechanism 170 converts the rotational motion of the mold clamping motor 160 into the linear motion of the cross head 151. The motion conversion mechanism 170 includes a screw shaft 171 and a screw nut 172 that is screwed onto the screw shaft 171. A ball or a roller may be interposed between the screw shaft 171 and the screw nut 172.

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

  In the mold closing process, the mold clamping motor 160 is driven to advance the cross head 151 to a mold closing completion position at a set speed, thereby moving the movable platen 120 forward and touching the movable platen 120 to the fixed mold 11. The position and speed of the cross head 151 are detected using, for example, the encoder 161 of the mold clamping motor 160. The encoder 161 detects the rotation of the mold clamping motor 160 and sends a signal indicating the detection result to the control device 700.

  In the mold clamping process, a mold clamping force is generated by further driving the mold clamping motor 160 to further advance the cross head 151 from the mold closing completion position to the mold clamping position. A cavity space 14 is formed between the movable platen 120 and the fixed mold 11 during mold clamping, and the injection device 300 fills the cavity space 14 with a liquid molding material. A molded product is obtained by solidifying the filled molding material. A plurality of cavity spaces 14 may be provided, and in this case, a plurality of molded products can be obtained simultaneously.

  In the mold opening process, the mold clamping motor 160 is driven to retract the cross head 151 to the mold opening completion position at a set speed, thereby retracting the movable platen 120 and separating the movable platen 120 from the fixed mold 11. Thereafter, the ejector device 200 ejects the molded product from the movable platen 120.

  Setting conditions in the mold closing process and the mold clamping process are collectively set as a series of setting conditions. For example, the speed and position (including the speed switching position, the mold closing completion position, and the mold clamping position) of the cross head 151 in the mold closing process and the mold clamping process are collectively set as a series of setting conditions. Instead of the speed and position of the cross head 151, the speed and position of the movable platen 120 may be set.

  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 magnification is also called toggle magnification. The toggle magnification changes in accordance with an 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 obtained from the position of the crosshead 151. When the link angle θ is 180 °, the toggle magnification is maximized.

  When the thickness of the mold apparatus 10 changes due to replacement of the mold apparatus 10 or temperature change of the mold apparatus 10, the mold thickness adjustment is performed so that a predetermined mold clamping force can be obtained at the time of mold clamping. In the mold thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle support 130 is set so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle when the movable platen 120 touches the fixed mold 11. adjust.

  The mold clamping apparatus 100 includes a mold thickness adjusting mechanism 180 that performs mold thickness adjustment by adjusting the distance L between the fixed platen 110 and the toggle support 130. The mold thickness adjusting mechanism 180 rotates a screw shaft 181 formed at the rear end portion of the tie bar 140, a screw nut 182 that is rotatably held by the toggle support 130, and a screw nut 182 that is screwed onto the screw shaft 181. And a mold thickness adjusting motor 183.

  The screw shaft 181 and the screw nut 182 are provided for each tie bar 140. The rotation of the mold thickness adjusting motor 183 may be transmitted to the plurality of screw nuts 182 via a rotation transmitting unit 185 configured by a belt, a pulley, or the like. A plurality of screw nuts 182 can be rotated synchronously. In addition, it is also possible to rotate the several screw nut 182 separately by changing the transmission path | route of the rotation transmission part 185. FIG.

  The rotation transmitting unit 185 may be configured with a gear or the like instead of a belt or a pulley. In this case, a passive gear is formed on the outer periphery of each screw nut 182, a drive gear is attached to the output shaft of the mold thickness adjusting motor 183, and a plurality of passive gears and an intermediate gear that meshes with the drive gear are in the central portion of the toggle support 130. It is held rotatably.

  The operation of the mold thickness adjusting mechanism 180 is controlled by the control device 700. The control device 700 drives the mold thickness adjusting motor 183 to rotate the screw nut 182, thereby adjusting the position of the toggle support 130 that rotatably holds the screw nut 182 with respect to the fixed platen 110. The interval L with the toggle support 130 is adjusted.

  In this embodiment, the screw nut 182 is rotatably held with respect to the toggle support 130, and the tie bar 140 on which the screw shaft 181 is formed is fixed with respect to the fixed platen 110. However, the present invention is not limited to this.

  For example, the screw nut 182 may be rotatably held with respect to the fixed platen 110 and the tie bar 140 may be fixed with respect to the toggle support 130. In this case, the interval L can be adjusted by rotating the screw nut 182.

  Further, the screw nut 182 may be fixed to the toggle support 130, and the tie bar 140 may be held rotatably with respect to the fixed platen 110. In this case, the interval L can be adjusted by rotating the tie bar 140.

  Furthermore, the screw nut 182 may be fixed to the fixed platen 110, and the tie bar 140 may be held rotatably with respect to the toggle support 130. In this case, the interval L can be adjusted by rotating the tie bar 140.

  The interval L is detected using the encoder 184 of the mold thickness adjusting motor 183. The encoder 184 detects the amount and direction of rotation of the mold thickness adjusting motor 183 and sends a signal indicating the detection result to the control device 700. The detection result of the encoder 184 is used for monitoring and controlling the position and interval L of the toggle support 130.

  The mold thickness adjusting mechanism 180 adjusts the interval L by rotating one of the screw shaft 181 and the screw nut 182 that are screwed together. A plurality of mold thickness adjusting mechanisms 180 may be used, and a plurality of mold thickness adjusting motors 183 may be used.

  The mold thickness adjusting mechanism 180 of this embodiment has a screw shaft 181 formed on the tie bar 140 and a screw nut 182 screwed to the screw shaft 181 in order to adjust the interval L. It is not limited to.

  For example, the mold thickness adjusting mechanism 180 may include a tie bar temperature controller that adjusts the temperature of the tie bar 140. The tie bar temperature controller is attached to each tie bar 140 and adjusts the temperature of the plurality of tie bars 140 in cooperation with each other. The higher the temperature of the tie bar 140, the larger the interval L. The temperature of the plurality of tie bars 140 can be adjusted independently.

  The tie bar temperature controller includes a heater such as a heater, and adjusts the temperature of the tie bar 140 by heating. The tie bar temperature controller may include a cooler such as a water cooling jacket, and the temperature of the tie bar 140 may be adjusted by cooling. The tie bar temperature controller may include both a heater and a cooler.

  The mold clamping device 100 of the present embodiment is a horizontal mold in which the mold opening / closing direction is the horizontal direction, but may be a vertical mold in which the mold opening / closing direction is the vertical direction. The vertical mold clamping apparatus includes a lower platen, an upper platen, a toggle support, a tie bar, a toggle mechanism, and a mold clamping motor. One of the lower platen and the upper platen is used as a fixed platen, and the other is used as a movable platen. A lower mold is attached to the lower platen, and an upper mold is attached to the upper platen. The lower die and the upper die constitute a mold apparatus. The lower mold may be attached to the lower platen via a rotary table. The toggle support is disposed below the lower platen. The toggle mechanism is disposed between the toggle support and the lower platen, and moves the movable platen up and down. The mold clamping motor operates a toggle mechanism. The tie bar extends in the vertical direction, passes through the lower platen, and connects the upper platen and the toggle support. When the mold clamping device is a saddle type, the number of tie bars is usually three. The number of tie bars is not particularly limited.

  The mold clamping device 100 according to the present embodiment includes the mold clamping motor 160 as a drive 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 opening and closing the mold and an electromagnet for mold clamping.

(Ejector device)
In the description of the ejector device 200, as in the description of the mold clamping device 100, the movement direction (right direction in FIGS. 1 and 2) of the movable platen 120 when the mold is closed is the front, and the movement of the movable platen 120 when the mold is opened. The direction (left direction in FIGS. 1 and 2) will be described as the rear.

  The ejector device 200 projects a molded product from the mold device 10. The ejector device 200 includes an ejector motor 210, a motion conversion mechanism 220, an ejector rod 230, and the like.

  The ejector motor 210 is attached to the movable platen 120. The ejector motor 210 is directly connected to the motion conversion mechanism 220, but may be connected to the motion conversion mechanism 220 via a belt, a pulley, or the like.

  The motion conversion mechanism 220 converts the rotational motion of the ejector motor 210 into the linear motion of the ejector rod 230. The motion conversion mechanism 220 includes a screw shaft and a screw nut that is screwed onto the screw shaft. A ball or a roller may be interposed between the screw shaft and the screw nut.

  The ejector rod 230 can be moved forward and backward in the through hole of the movable platen 120. The front end portion of the ejector rod 230 is in contact with the movable member 15 disposed inside the movable platen 120 so as to be able to advance and retract. The front end portion of the ejector rod 230 may or may not be connected to the movable member 15.

  The ejector device 200 performs the ejection process under the control of the control device 700.

  In the ejecting step, the ejector motor 210 is driven to advance the ejector rod 230 at a set speed, thereby moving the movable member 15 forward and ejecting the molded product. Thereafter, the ejector motor 210 is driven to retract the ejector rod 230 at the set speed, and the movable member 15 is retracted to the original position. The position and speed of the ejector rod 230 are detected using the encoder 211 of the ejector motor 210, for example. The encoder 211 detects the rotation of the ejector motor 210 and sends a signal indicating the detection result to the control device 700.

(Injection device)
In the description of the injection device 300, unlike the description of the mold clamping device 100 and the description of the ejector device 200, the moving direction of the screw 330 during filling (the left direction in FIGS. 1 and 2) is the front, and the screw 330 during weighing is used. The moving direction (right direction in FIGS. 1 and 2) will be described as the rear.

  The injection device 300 is installed on a slide base 301 that can move forward and backward with respect to the frame Fr, and can move forward and backward with respect to the mold device 10. The injection apparatus 300 is touched by the mold apparatus 10 and fills the cavity space 14 in the mold apparatus 10 with a molding material. The injection device 300 includes, for example, a cylinder 310, a nozzle 320, a screw 330, a metering motor 340, an injection motor 350, a pressure detector 360, and the like.

  The cylinder 310 heats the molding material supplied to the inside from the supply port 311. The supply port 311 is formed at the rear part 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. In front of the cooler 312, a heater 313 such as a band heater and a temperature detector 314 are provided on the outer periphery of the cylinder 310.

  The cylinder 310 is divided into a plurality of zones in the axial direction of the cylinder 310 (the left-right direction in FIGS. 1 and 2). A heater 313 and a temperature detector 314 are provided in each zone. For each zone, the control device 700 controls the heater 313 so that the temperature detected by the temperature detector 314 becomes a set temperature.

  The nozzle 320 is provided at the front end of the cylinder 310 and is pressed against the mold apparatus 10. 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 disposed in the cylinder 310 so as to be rotatable and movable back and forth. When the screw 330 is rotated, the molding material is fed forward along the spiral groove of the screw 330. The molding material is gradually melted by the heat from the cylinder 310 while being fed forward. As the liquid molding material is fed forward of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. Thereafter, 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 apparatus 10.

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

  When the screw 330 is moved forward, the backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330 and retracts to a closed position (see FIG. 2) that closes 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 backflow prevention ring 331 is pushed forward by the pressure of the molding material sent forward along the spiral groove of the screw 330 to open the flow path of the molding material. Advance to (see FIG. 1). Thereby, a molding material is sent ahead of the screw 330.

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

  The injection device 300 may have a drive source that advances and retracts the backflow prevention ring 331 between the open position and the closed position.

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

  The injection motor 350 moves the screw 330 back and forth. Between the injection motor 350 and the screw 330, a motion conversion mechanism for converting the rotational motion of the injection motor 350 into the linear motion of the screw 330 is provided. The motion conversion mechanism includes, for example, a screw shaft and a screw nut that is screwed onto the screw shaft. A ball, a roller, or the like may be provided between the screw shaft and the screw nut. The drive source for moving the screw 330 back and forth is not limited to the injection motor 350, and may be a hydraulic cylinder, for example.

  The pressure detector 360 detects the pressure transmitted between the injection motor 350 and the screw 330. The pressure detector 360 is provided in a force transmission path between the injection motor 350 and the screw 330 and detects the pressure acting on the pressure detector 360.

  The pressure detector 360 sends a signal indicating the detection result to the control device 700. The detection result of the pressure detector 360 is used for control and monitoring of the pressure received by the screw 330 from the molding material, the back pressure against the screw 330, the pressure acting on the molding material from the screw 330, and the like.

  The injection device 300 performs a filling process, a pressure holding process, a weighing process, and the like under the control of the control device 700.

  In the filling step, the injection motor 350 is driven to advance the screw 330 at a set speed, and the liquid molding material accumulated in front of the screw 330 is filled into the cavity space 14 in the mold apparatus 10. The position and speed of the screw 330 are detected using an encoder 351 of the injection motor 350, for example. The encoder 351 detects the rotation of the injection motor 350 and sends a signal indicating the detection result to the control device 700. When the detection value of the pressure detector 360 reaches a predetermined value, switching from the filling process to the pressure holding process (so-called V / P switching) is performed. The V / P switching may be performed when the position of the screw 330 reaches the set position. A position where the V / P switching is performed is also referred to as a V / P switching position. The set speed of the screw 330 may be changed according to the position and time of the screw 330.

  In addition, when the detected value of the pressure detector 360 reaches a predetermined value in the filling process, the screw 330 may be temporarily stopped at that position, and then V / P switching may be performed. Immediately before the V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed.

  In 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 portion of the screw 330 (hereinafter also referred to as “holding pressure”) is maintained at a set pressure, The remaining molding material is pushed toward the mold apparatus 10. Insufficient molding material due to cooling shrinkage in the mold apparatus 10 can be replenished. The holding pressure is detected using a pressure detector 360, for example. The pressure detector 360 sends a signal indicating the detection result to the control device 700. The set value of the holding pressure may be changed according to the elapsed time from the start of the pressure holding process.

  In the pressure holding process, the molding material in the cavity space 14 in the mold apparatus 10 is gradually cooled, and when the pressure holding process is completed, the inlet of the cavity space 14 is closed with the solidified molding material. This state is called a gate seal, and the backflow of the molding material from the cavity space 14 is prevented. After the pressure holding process, the cooling process is started. In the cooling process, the molding material in the cavity space 14 is solidified. In order to shorten the molding cycle, a metering step may be performed during the cooling 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 fed forward along the spiral groove of the screw 330. Along with this, the molding material is gradually melted. As the liquid molding material is fed forward of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. The rotational speed of the screw 330 is detected by using, for example, the encoder 341 of the weighing motor 340. The encoder 341 sends a signal indicating the detection result to the control device 700.

  In the metering step, the set back pressure may be applied to the screw 330 by driving the injection motor 350 in order to limit the rapid retreat of the screw 330. The back pressure with respect to the screw 330 is detected using, for example, a pressure detector 360. The pressure detector 360 sends a signal indicating the detection result to the control device 700. When the screw 330 is retracted to the measurement completion position and a predetermined amount of molding material is accumulated in front of the screw 330, the measurement process is completed.

  In addition, although the injection apparatus 300 of this embodiment is an inline screw system, a pre-plastic system etc. may be sufficient. A pre-plastic injection device supplies a molding material melted in a plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into a mold device. In the plasticizing cylinder, a screw is rotatably or rotatably and reciprocally disposed, and in the injection cylinder, a plunger is reciprocally disposed.

(Moving device)
In the description of the moving device 400, similarly to the description of the injection device 300, the moving direction of the screw 330 during filling (the left direction in FIGS. 1 and 2) is the front, and the moving direction of the screw 330 during weighing (see FIGS. 1 and 2). In the following description, the right direction in FIG.

  The moving device 400 moves the injection device 300 forward and backward with respect to the mold device 10. Further, the moving device 400 presses the nozzle 320 against the mold device 10 to generate a nozzle touch pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

  The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bi-directionally rotatable pump, and by switching the rotation direction of the motor 420, hydraulic fluid (for example, oil) is sucked from one of the first port 411 and the second port 412 and discharged from the other. Then, hydraulic pressure is generated. The hydraulic pump 410 can also suck the working fluid from the tank 413 and discharge the working fluid from either the first port 411 or the second port 412.

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

  The hydraulic cylinder 430 includes a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is fixed with respect to the injection device 300. The piston 432 divides the interior of the cylinder body 431 into a front chamber 435 as a first chamber and a rear chamber 436 as a second chamber. The piston rod 433 is fixed to the fixed platen 110. Since the piston rod 433 passes through the front chamber 435, the cross-sectional area of the front chamber 435 is smaller than the cross-sectional area of the rear chamber 436.

  The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via the first flow path 401. The hydraulic fluid discharged from the first port 411 is supplied to the front chamber 435 via the first flow path 401, whereby the injection device 300 is pushed forward. The injection device 300 is advanced, and the nozzle 320 is pressed against the fixed mold 11. The front chamber 435 functions as a pressure chamber that generates the nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

  On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via the second flow path 402. The hydraulic fluid discharged from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 through the second flow path 402, whereby the injection device 300 is pushed backward. The injection device 300 is retracted, and the nozzle 320 is separated from the fixed mold 11.

  The first relief valve 441 opens when the pressure in the first flow path 401 exceeds a set value, returns the excess hydraulic fluid in the first flow path 401 to the tank 413, and Keep pressure below set point.

  The second relief valve 442 opens when the pressure in the second flow path 402 exceeds a set value, returns excess hydraulic fluid in the second flow path 402 to the tank 413, and Keep pressure below set point.

  The flushing valve 443 is a valve that adjusts the excess or deficiency of the circulating amount of the hydraulic fluid caused by the difference between the cross-sectional area of the front chamber 435 and the cross-sectional area of the rear chamber 436. It consists of a 4-port spool valve.

  The first check valve 451 opens when the pressure in the first flow path 401 is lower than the pressure in the tank 413, and supplies the working fluid from the tank 413 to the first flow path 401.

  The second check valve 452 opens when the pressure in the second flow path 402 is lower than the pressure in the tank 413, and supplies the working fluid from the tank 413 to the second flow path 402.

  The electromagnetic switching valve 453 is a control valve that controls the flow of hydraulic fluid between the front chamber 435 of the hydraulic cylinder 430 and the first port 411 of the hydraulic pump 410. The electromagnetic switching valve 453 is provided in the middle of the first flow path 401, for example, and controls the flow of hydraulic fluid in the first flow path 401.

  The electromagnetic switching valve 453 is configured by a 2-position 2-port spool valve as shown in FIGS. 1 and 2, for example. When the spool valve is in the first position (the position on the left side in FIGS. 1 and 2), flow in both directions between the front chamber 435 and the first port 411 is allowed. On the other hand, when the spool valve is in the second position (the right position in FIGS. 1 and 2), the flow from the front chamber 435 to the first port 411 is restricted. In this case, the flow from the first port 411 to the front chamber 435 is not limited, but may be limited.

  The first pressure detector 455 detects the hydraulic pressure in the front chamber 435. Since the nozzle touch pressure is generated by the fluid pressure in the front chamber 435, the nozzle touch pressure can be detected using the first pressure detector 455. The first pressure detector 455 is provided in the middle of the first flow path 401, for example, and is provided at a position on the front chamber 435 side with respect to the electromagnetic switching valve 453. Regardless of the state of the electromagnetic switching valve 453, the nozzle touch pressure can be detected.

  The second pressure detector 456 is provided in the middle of the first flow path 401 and is provided at a position on the first port 411 side with the electromagnetic switching valve 453 as a reference. The second pressure detector 456 detects the hydraulic pressure between the electromagnetic switching valve 453 and the first port 411. When the electromagnetic switching valve 453 is allowed to flow in both directions between the first port 411 and the front chamber 435, the hydraulic pressure between the first port 411 and the electromagnetic switching valve 453, the electromagnetic switching valve 453, and the front The hydraulic pressure between the chamber 435 and the chamber 435 is equal. Therefore, in this state, the nozzle touch pressure can be detected using the second pressure detector 456.

  In the present embodiment, the nozzle touch pressure is detected using a pressure detector provided in the middle of the first flow path 401, but the nozzle touch pressure may be detected using a load cell provided in the nozzle 320, for example. Good. That is, the pressure detector that detects the nozzle touch pressure may be provided in either the moving device 400 or the injection device 300.

  In the present embodiment, the hydraulic cylinder 430 is used as the moving device 400, but the present invention is not limited to this.

(Control device)
The control device 700 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 a program stored in the storage medium 702. In addition, 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 is connected to the operation device 750 and the display device 760. The operation device 750 receives an input operation by a user and outputs a signal corresponding to the input operation to the control device 700. The display device 760 displays an operation screen corresponding to an input operation on the operation device 750 under the control of the control device 700. The operation screen is used for setting the injection molding machine. A plurality of operation screens are prepared and displayed by switching or overlapping. The user performs settings of the injection molding machine (including input of set values) by operating the operation device 750 while viewing the operation screen displayed on the display device 760. The operation device 750 and the display device 760 may be configured with a touch panel, for example, and may be integrated. In addition, although the operating device 750 and the display device 760 of this embodiment are integrated, you may provide independently. In addition, a plurality of operation devices 750 may be provided.

(Compression molding)
The ejector rod 230 of the ejector apparatus 200 compresses the molding material filled in the cavity space 14 of the mold apparatus 10, and a molded article formed by the compression (hereinafter also referred to as “compressed molded article”). It is used for both protrusions from the mold apparatus 10. The molding material is compressed before the molding material is completely solidified.

  The ejector rod 230 is allowed to advance and retract in a through hole that penetrates the movable platen 120 in the front-rear direction. The front end portion of the ejector rod 230 is in contact with the movable member 15 which is disposed inside the movable mold 12 so as to be able to advance and retract.

  As shown in FIGS. 3 to 6, the movable member 15 includes a plate-like ejector plate 21 perpendicular to the front-rear direction, a rod-like compression core pin 22 extending forward from the ejector plate 21, and extending forward from the ejector plate 21. It has a rod-like ejector pin 23.

  The ejector plate 21 is pushed forward by an ejector rod 230 disposed rearward of the ejector plate 21. Further, the ejector plate 21 is pushed rearward by the spring 16 disposed in front of the ejector plate 21.

  The compression core pin 22 extends forward from the ejector plate 21 and penetrates the movable mold 12. The front end surface of the compression core pin 22 is a part of the wall surface of the cavity space 14. The compression core pin 22 advances and retreats together with the ejector plate 21, and compresses the molding material 2, depressurizes the molded product that has been compression molded, and ejects the molded product that has been depressurized.

  The ejector pin 23 extends forward from the ejector plate 21 and penetrates the movable mold 12. As shown in FIG. 3, the molding material 2 flowing through the runner 18 is stuck to the front end portion of the ejector pin 23. The hugging molding material 2 is in close contact with the front end portion of the ejector pin 23 by solidifying. The ejector pin 23 is used for protruding the molding material 2 solidified by the runner 18.

  The front end portion of the ejector rod 230 is not connected to the movable member 15, but may be connected to the movable member 15. When the front end portion of the ejector rod 230 is connected to the movable member 15, the spring 16 described later may be omitted.

  When the ejector motor 210 is driven to move the ejector rod 230 forward, the movable member 15 moves forward, and the molding material 2 is compressed and the molded product that is compression-molded is ejected.

  On the other hand, when the ejector rod 230 is driven to retract the ejector rod 230, the movable member 15 is retracted while being pressed against the ejector rod 230 by the elastic restoring force of the spring 16, and the molded product is depressurized. The depressurized molded product is ejected from the movable mold 12 by the advancement of the ejector rod 230.

  The control device 700 controls the compression of the molding material 2 by controlling the advancement of the ejector rod 230, and controls the decompression of the molded product by controlling the retraction of the ejector rod 230, thereby controlling the 230 advancement of the ejector rod. This controls the extrusion of the molded product that has been depressurized.

  Hereinafter, the operation of the ejector rod 230 will be described with reference to FIGS. FIG. 3 is a partially enlarged view of FIG. 2 and shows a state where the ejector rod is in the compression standby position. FIG. 4 is a view showing a state in which the ejector rod has advanced from the compression standby position shown in FIG. 3 to the compression position. FIG. 5 is a view showing a state where the ejector rod is retracted from the compression position shown in FIG. 4 to the compression standby position. 6 is a view showing a state in which the ejector rod has advanced from the compression standby position shown in FIG. 5 to the protruding position.

  The control device 700 advances the ejector rod 230 from the compression standby position shown in FIG. 3 to the compression position shown in FIG. 4 between the start of the filling process and the completion of the pressure holding process. Thereby, the movable member 15 is advanced, and the molding material 2 filled in the cavity space 14 is compressed. The ejector rod 230 is not in contact with the movable member 15 in FIG. 3 when in the compression standby position, but may be in contact with the movable member 15. In the latter case, the ejector rod 230 may be connected to the movable member 15.

  The start of advancement of the ejector rod 230 may be performed during the filling process, and may be performed before the flow front of the molding material 2 reaches the end of the flow path. Further, the completion of the forward movement of the ejector rod 230 may be substantially simultaneous with the completion of the filling process, and may be substantially simultaneously with the time when the flow front of the molding material 2 reaches the end of the flow path. Preferably, the forward start of the ejector rod 230 is performed substantially at the same time that the flow front end of the molding material 2 reaches the end point of the flow path.

  The advance of the ejector rod 230 may be started after the filling process is started and before the pressure holding process is completed, or may be performed after the pressure holding process is started. Similarly, the advance completion of the ejector rod 230 may be performed after the filling process is started and before the pressure holding process is completed, and may be performed before the flow front of the molding material 2 reaches the end of the flow path. Then, it may be performed after the flow front of the molding material 2 reaches the end point of the flow path.

  By the way, in the mold apparatus 10, the molding material 2 passes through a sprue 17 formed in the fixed mold 11, a runner 18 branched at the end portion of the sprue 17, and a gate 19 provided at the end portion of the runner 18. To the cavity space 14.

  In order to detect the flow of the molding material 2 inside the mold apparatus 10, pressure detectors such as a runner pressure detector 31 and a cavity space pressure detector 32 are provided inside the mold apparatus 10. The runner pressure detector 31 is provided, for example, at the end of the runner 18 and detects the pressure of the molding material 2 that passes through the runner 18. The cavity space pressure detector 32 is provided on the back side of the core forming the wall surface of the cavity space 14 and detects the pressure of the molding material 2 filled in the cavity space 14. The runner pressure detector 31 and the cavity space pressure detector 32 are provided in the fixed mold 11 in FIGS. 3 to 6, but may be provided in the movable mold 12.

  When the molding material 2 reaches the installation position of the pressure detector provided inside the mold apparatus 10, the pressure of the molding material 2 acts on the pressure detector, so that the detection value of the pressure detector increases. The arrival of the molding material 2 at a predetermined position can be detected from the increase in the detection value of the pressure detector. For example, when the detection value of the pressure detector exceeds a set value, it is assumed that the molding material 2 has reached the installation position of the pressure detector. Alternatively, it is assumed that the molding material 2 has reached the installation position of the pressure detector when the time differential value of the detection value of the pressure detector exceeds the set value.

  The control device 700 starts to advance the ejector rod 230 based on the detection result of the pressure detector provided inside the mold apparatus 10. The timing of starting the forward movement of the ejector rod 230 can be adjusted according to the filling state of the molding material 2 in the mold apparatus 10, and the quality of the molded product can be stabilized.

  For example, the control device 700 detects the arrival of the molding material 2 at a predetermined position based on the detection result of the pressure detector such as the runner pressure detector 31, and starts the compression operation in which the elapsed time from the arrival is preset. When the time is reached, the ejector rod 230 begins to advance. Variations in the arrival timing of the molding material 2 to a predetermined position can be absorbed, and variations in peak pressure can be absorbed.

  Further, the control device 700 detects the flow front position of the molding material 2 based on the detection result of the pressure detector such as the runner pressure detector 31, and when the detected position reaches a preset compression operation start position, The advancement of the ejector rod 230 may be started. The detection of the flow front position of the molding material 2 may be performed, for example, by measuring an elapsed time from when the molding material 2 reaches a predetermined position. As the elapsed time advances, the flow front position of the molding material 2 approaches the end point of the flow path.

  In addition, although the control apparatus 700 of this embodiment performs the advance start of the ejector rod 230 based on the detection result of the pressure detector provided in the inside of the metal mold | die apparatus 10, this invention is not limited to this.

  For example, the control device 700 may start the forward movement of the ejector rod 230 based on a detection result of a temperature detector provided in the mold apparatus 10. When the molding material 2 arrives at or near the installation position of the temperature detector, the molding material 2 is at a higher temperature than the mold apparatus 10, and therefore the measured value of the temperature detector increases. The arrival of the molding material 2 at a predetermined position can be detected from the rise in the measured value of the temperature detector. For example, when the measured value of the temperature detector exceeds a set value, it is assumed that the molding material 2 has arrived at or near the installation position of the temperature detector. Alternatively, it is assumed that the molding material 2 has arrived at or near the installation position of the temperature detector when the time differential value of the measurement value of the temperature detector exceeds the set value.

  Further, the control device 700 may start the forward movement of the ejector rod 230 based on the detection result of the compression core pin pressure detector 33 that detects the pressure acting on the compression core pin 22. This is because the compression core pin 22 is pressed when the molding material 2 reaches the cavity space 14. When the ejector rod 230 is in contact with the movable member 15 when the ejector rod 230 starts moving forward, when the molding material 2 reaches the cavity space 14, not only the movable member 15 but also the ejector rod 230 is pressed. Therefore, an ejector rod pressure detector 34 that detects the pressure acting on the ejector rod 230 can be used.

  The control device 700 may stop the ejector rod 230 for a predetermined time at the compression position after moving the ejector rod 230 forward to the compression position shown in FIG. 4 and before retracting the ejector rod 230 from the compression position. The molding material 2 is sufficiently pressed against the wall surface of the cavity space 14 to improve transferability.

  The control device 700 retracts the ejector rod 230 from the compression position shown in FIG. 4 to the compression standby position shown in FIG. Thereby, the movable member 15 is retracted, and the molded product compression-molded in the cavity space 14 is depressurized.

  Note that the position of the ejector rod 230 at the completion of the depressurization may be a position different from the compression standby position shown in FIG. 5, may be a position ahead of the compression standby position, or may be a position behind the compression standby position. It may be a position.

  After the compression of the molding material 2, the control device 700 performs the primary depressurization for lowering the pressure of the molded product in a predetermined pattern and before the ejection of the compression molded molded product, and the ejector rod 230 after the primary depressurization. Is retreated to a predetermined position to control secondary depressurization that further lowers the pressure of the molded product. In the primary depressurization, the pressure of the compression-molded molded product is gradually reduced in a predetermined pattern while suppressing the collapse of the shape and dimensions of the compression-molded molded product.

  FIG. 7 is a diagram comparing the depressurization pattern of the compression-molded product according to the example and the depressurization pattern of the compression-molded product according to the comparative example. Fig.7 (a) is a figure which shows the depressurization pattern of the molded article compression-molded by 1st Example. FIG.7 (b) is a figure which shows the depressurization pattern of the molded article compression-molded by 2nd Example. FIG.7 (c) is a figure which shows the depressurization pattern of the molded article compression-molded by 3rd Example. FIG.7 (d) is a figure which shows the depressurization pattern of the molded article compression-molded by the comparative example.

  In the comparative example of FIG. 7D, after the molding material 2 is compressed, the ejector rod 230 is retracted to a predetermined position, and the pressure of the compression-molded molded product is discontinuously reduced to substantially zero. For this reason, a large residual stress is generated in the molded product after depressurization, the surface shape changes greatly due to the residual stress, and the surface accuracy of the molded product is poor.

  On the other hand, in the first embodiment of FIG. 7A, the pressure of the molded product that has been compression-molded is continuously reduced over time in the primary depressurization. In the second embodiment of FIG. 7B, the pressure of the compression molded product is kept constant after being continuously reduced in the primary depressurization. In the third embodiment shown in FIG. 7 (c), the pressure of the compression-molded product is lowered stepwise in the primary depressurization. In the first to third embodiments, in the secondary depressurization, the pressure of the compression molded product is decreased more rapidly than the primary depressurization. In the secondary depressurization, the pressure of the compression molded product may be reduced to substantially zero.

  According to 1st Example-3rd Example, after compression of the molding material 2, it is compression by performing primary depressurization and secondary depressurization before extrusion of the compression-molded molded product. It is possible to reduce the residual stress of the molded product by reducing the pressure of the molded product that has been compression-molded while suppressing the collapse of the shape and dimensions of the molded product. As a result, a change in the surface shape due to the residual stress can be suppressed, so that the surface accuracy of the molded product can be improved. This effect is particularly remarkable when the molded product has a thin part and a thick part (for example, a lens). This is because the stress that compresses the molding material 2 tends to concentrate on the thin portion.

  In the primary depressurization, the pressure of the compression molded product may or may not be detected. In the latter case, the relationship between the position of the ejector rod 230 and the pressure of the compression molded product is obtained by a test or the like, and stored in the storage medium 702 in advance. By controlling the position of the ejector rod 230 according to the time based on the stored data, the pressure of the compression-molded molded product can be lowered in a predetermined pattern.

  The controller 700 may detect the pressure of the compression molded product in the primary depressurization and control the retreat of the ejector rod 230 based on the detection result. The pressure of the compression molded product is detected using, for example, a cavity space pressure detector 32. By detecting the actual pressure of the compression molded product, the actual pressure can be accurately reduced in a predetermined pattern.

  For example, the controller 700 detects the pressure of the compression-molded molded product in the primary depressurization, and controls the retreat of the ejector rod 230 so that the deviation between the detected value and the target value becomes zero. For this control, for example, a PI (Proportional Integral) operation or a PID (Proportional Integral Derivative) operation is used.

  In the primary depressurization, the pressure of the compression molded product can also be detected by the runner pressure detector 31. This is because the cavity space 14 and the runner 18 are connected.

  In the primary depressurization, the pressure of the compression-molded molded product can be detected by the compression core pin pressure detector 33 and the ejector rod pressure detector 34. This is because the pressure of the compression-molded product acts on the compression core pin 22 and the ejector rod 230.

  On the other hand, the controller 700 may control the retreat of the ejector rod 230 in the secondary depressurization regardless of the detected pressure value of the compression molded product. For example, the control device 700 retracts the ejector rod 230 to a preset position at a preset speed in the secondary decompression. The retracting speed of the ejector rod 230 in the secondary depressurization may be larger than the retracting speed of the ejector rod 230 in the primary depressurizing.

  The control device 700 may start the decompression of the compression molded product, that is, start the retraction of the ejector rod 230 before the pressure holding step is finished. Since the compression-molded molded product is not completely hardened before the pressure holding step is completed, the pressure of the compression-molded molded product is likely to be lowered, and the residual stress of the molded product is likely to be lowered.

  The control device 700 may perform the completion of the depressurization of the compression-molded molded product, that is, the completion of the retraction of the ejector rod 230 before the completion of the pressure holding process. Since the compression-molded molded product is not completely hardened before the pressure holding step is completed, the pressure of the compression-molded molded product is likely to be lowered, and the residual stress of the molded product is likely to be lowered.

  The compression molded product is completely solidified at the end of the cooling step. Therefore, the control device 700 may perform the start of the backward movement of the ejector rod 230 and the completion of the backward movement of the ejector rod 230 before the end of the cooling process.

(Deformation and improvement)
The embodiments of the injection molding machine have been described above, but the present invention is not limited to the above embodiments and the like, and various modifications are possible within the scope of the gist of the present invention described in the claims. Improvements are possible.

  For example, the movable member 15 of the above embodiment is used for both (1) compression of the molding material 2 filled in the cavity space 14 and (2) extrusion of the molded product solidified in the cavity space 14 (1 ) Used only for compression (2) Not used for ejection. In this case, the protruding member is disposed in the mold apparatus 10 separately from the movable member 15.

  When the protruding member and the movable member 15 are provided separately, the ejector device 200 may function as a driving device that drives the protruding member and the movable member 15 independently. You may function as a drive device which drives only a member. In the latter case, for example, a hydraulic cylinder or the like is separately provided as a driving device for driving the movable member 15.

  The movable member 15 of the above embodiment is disposed on the movable platen 120 side, but may be disposed on the fixed mold 11 side. The movable member 15 may be disposed on both sides of the movable platen 120 and the fixed mold 11. The arrangement of the ejector device 200 is selected according to the arrangement of the movable member 15.

DESCRIPTION OF SYMBOLS 10 Mold apparatus 11 Fixed mold 12 Movable mold 14 Cavity space 15 Movable member 16 Spring 17 Sprue 18 Runner 19 Gate 21 Ejector plate 22 Compression core pin 23 Ejector pin 31 Runner pressure detector 32 Cavity space pressure detector 33 Compression core pin pressure Detector 34 Ejector rod pressure detector 200 Ejector device 210 Ejector motor 220 Motion conversion mechanism 230 Ejector rod 700 Control device

Claims (5)

A control device for controlling the advance and retreat of the movable member used for compressing the molding material filled in the cavity space of the mold device;
The controller controls the compression of the molding material by controlling the advance of the movable member, and then performs primary depressurization to lower the pressure of the molded product molded by the compression in a predetermined pattern, An injection molding machine that controls secondary depressurization that further lowers the pressure of the molded product by retracting the movable member to a predetermined position after the second depressurization.   2. The injection molding machine according to claim 1, wherein the control device detects a pressure of the molded product in the primary depressurization and retracts the movable member based on the detection result.   3. The injection molding machine according to claim 1, wherein the control device starts depressurization of the molded product before the end of the pressure holding process.   The injection control machine according to any one of claims 1 to 3, wherein the control device completes the depressurization of the molded product before the pressure holding step. The movable member is used for both the compression of the molding material filled in the cavity space of the mold apparatus and the ejection of the molded product formed by the compression from the mold apparatus. And
After the compression, the control device lowers the pressure of the molded product in a predetermined pattern before the ejection, and retracts the ejector rod to a predetermined position after the primary pressure is released. The injection molding machine according to any one of claims 1 to 4, wherein the secondary depressurization for further lowering the pressure of the molded product is controlled.

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