Control method for injection molding machine and control device for injection molding machine

Abstract

To provide a technology that combines filling and transferability with reduced molding cycle time.SOLUTION: The method of controlling an injection molding machine controls an injection molding machine that injects molding material from a nozzle into a mold device to form a molded product including a skin layer and a core layer within said mold device. The method of controlling the injection molding machine controls the temperature of the molding material corresponding to the skin layer to be higher than the temperature of the molding material corresponding to the core layer at the start of the injection process.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a control method for an injection molding machine and a control device for an injection molding machine.

Background Art

[0002] The injection nozzle of Patent Document 1 fills a mold with molten resin. The injection nozzle includes a nozzle body portion, a heater provided on the outer periphery of the nozzle body portion, and a small-diameter short protruding portion provided at the tip of the nozzle body portion. The small-diameter short protruding portion abuts against the sprue bush of the mold and injects the molten resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An injection molding machine forms a molded product in a mold device by injecting a molding material from a nozzle into the mold device. The injection molding machine repeatedly performs forming the molded product.

[0005] If the heating temperature of the nozzle is set low, the fluidity of the molding material decreases, and the filling property of the molding material with respect to the mold device and the shape transfer property from the mold device to the molded product decrease.

[0006] On the other hand, if the heating temperature of the nozzle is set high, it takes time to solidify the molten molding material, and the molding cycle time becomes long.

[0007] One aspect of the present invention provides a technique that achieves both filling property and transfer property and shortening of the molding cycle time.

Means for Solving the Problems

[0008] A control method for an injection molding machine according to one aspect of the present invention is to Provided at the tip of the cylinder control an injection molding machine that forms a molded product including a skin layer and a core layer in the mold device by injecting a molding material from a nozzle into the mold device. The control method for the injection molding machine is, at the start of the injection process, Inside the nozzle control the temperature of the molding material corresponding to the skin layer to be Inside the cylinder higher than the temperature of the molding material corresponding to the core layer.

Advantages of the Invention

[0009] According to one aspect of the present invention, by controlling the temperature of the molding material corresponding to the skin layer to be relatively high at the start of the injection process, the filling property and the transfer property can be improved, and by controlling the temperature of the molding material corresponding to the core layer to be relatively low at the start of the injection process, the molding cycle time can be shortened. Therefore, it is possible to achieve both the filling property and the transfer property and the shortening of the molding cycle time.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

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

[0012] (Injection molding machine) FIG. 1 is a diagram showing the state of an injection molding machine according to an embodiment when the mold is fully opened. FIG. 2 is a diagram showing the state of the injection molding machine according to an embodiment when the mold is clamped. In this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction represent the horizontal direction, and the Z-axis direction represents the vertical direction. When the mold clamping device 100 is a horizontal mold, 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 non-operation side.

[0013] As shown in FIGS. 1 to 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 formed by the mold device 800, an injection device 300 that injects a molding material into the mold device 800, a moving device 400 that moves the injection device 300 forward and backward with respect to the mold device 800, a control device 700 that controls each component of the injection molding machine 10, and a frame 900 that supports each component of the injection molding machine 10. The frame 900 includes a mold clamping device frame 910 that supports the mold clamping device 100 and an injection device frame 920 that supports the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are each installed on the floor 2 via a leveling adjuster 930. The control device 700 is disposed in the internal space of the injection device frame 920. Hereinafter, each component of the injection molding machine 10 will be described.

[0014] (Mold clamping device) In the description of the clamping device 100, the moving direction of the movable platen 120 when the mold is closed (for example, the positive X-axis direction) is defined as the front, and the moving direction of the movable platen 120 when the mold is opened (for example, the negative X-axis direction) is defined as the rear for the description.

[0015] The clamping device 100 performs mold closing, pressure boosting, mold clamping, pressure release, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a movable mold 820.

[0016] The clamping device 100 is, for example, a horizontal type, and the mold opening / closing direction is a horizontal direction. The clamping device 100 has a fixed platen 110 to which the fixed mold 810 is attached, a movable platen 120 to which the movable mold 820 is attached, and a moving mechanism 102 that moves the movable platen 120 in the mold opening / closing direction with respect to the fixed platen 110.

[0017] The fixed platen 110 is fixed to the clamping device frame 910. The fixed mold 810 is attached to the opposing surface of the fixed platen 110 with respect to the movable platen 120.

[0018] The movable platen 120 is disposed movably in the mold opening / closing direction with respect to the clamping device frame 910. A guide 101 for guiding the movable platen 120 is laid on the clamping device frame 910. The movable mold 820 is attached to the opposing surface of the movable platen 120 with respect to the fixed platen 110.

[0019] The moving mechanism 102 performs mold closing, pressure boosting, mold clamping, pressure release, and mold opening of the mold device 800 by advancing and retracting the movable platen 120 with respect to the fixed platen 110. The moving mechanism 102 has a toggle support 130 disposed at an interval from the fixed platen 110, a tie bar 140 connecting the fixed platen 110 and the toggle support 130, a toggle mechanism 150 that moves the movable platen 120 in the mold opening / closing direction with respect to the toggle support 130, a clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the clamping motor 160 into a linear motion, and a mold thickness adjustment mechanism 180 that adjusts the interval between the fixed platen 110 and the toggle support 130.

[0020] The toggle support 130 is disposed at a distance from the fixed platen 110 and is placed movably in the mold opening / closing direction on the mold clamping device frame 910. Note that the toggle support 130 may be movably arranged along a guide laid on the mold clamping device frame 910. The guide of the toggle support 130 may be common with the guide 101 of the movable platen 120.

[0021] Note that in the present embodiment, the fixed platen 110 is fixed to the mold clamping device frame 910 and the toggle support 130 is movably arranged in the mold opening / closing direction with respect to the mold clamping device frame 910. However, the toggle support 130 may be fixed to the mold clamping device frame 910 and the fixed platen 110 may be movably arranged in the mold opening / closing direction with respect to the mold clamping device frame 910.

[0022] The tie bar 140 connects the fixed platen 110 and the toggle support 130 with a space L in the mold opening / closing direction. A plurality of (for example, four) tie bars 140 may be used. The plurality of tie bars 140 are arranged in parallel in the mold opening / closing direction and extend according to the clamping force. At least one tie bar 140 may be provided with a tie bar strain detector 141 for detecting the strain of the tie bar 140. The tie bar strain detector 141 sends a signal indicating the detection result to the control device 700. The detection result of the tie bar strain detector 141 is used for detecting the clamping force and the like.

[0023] Note that in the present embodiment, the tie bar strain detector 141 is used as the clamping force detector for detecting the clamping force. However, the present invention is not limited to this. The 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, etc., and its mounting position is not limited to the tie bar 140.

[0024] The toggle mechanism 150 is disposed between the movable platen 120 and the toggle support 130, and moves the movable platen 120 in the mold opening and closing direction with respect to the toggle support 130. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening and closing direction, and a pair of link groups that flex by the movement of the crosshead 151. Each of the pair of link groups has a first link 152 and a second link 153 that are flexibly connected by a pin or the like. The first link 152 is swingably attached to the movable platen 120 by a pin or the like. The second link 153 is swingably attached to the toggle support 130 by 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 advanced and retracted with respect to the toggle support 130, the first link 152 and the second link 153 flex, and the movable platen 120 advances and retracts with respect to the toggle support 130.

[0025] Note that the configuration of the toggle mechanism 150 is not limited to the configurations shown in FIGS. 1 and 2. For example, in FIGS. 1 and 2, the number of nodes of each link group is five, but it may be four, and one end of the third link 154 may be coupled to the node between the first link 152 and the second link 153.

[0026] The mold clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The mold clamping motor 160 flexes the first link 152 and the second link 153 by advancing and retracting the crosshead 151 with respect to the toggle support 130, and advances and retracts the movable platen 120 with respect 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.

[0027] The motion conversion mechanism 170 converts the rotational motion of the mold clamping motor 160 into the linear motion of the crosshead 151. The motion conversion mechanism 170 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.

[0028] The mold clamping device 100 performs a mold closing process, a pressure boosting process, a mold clamping process, a pressure releasing process, a mold opening process, etc. under the control of the control device 700.

[0029] In the mold closing process, the mold clamping motor 160 is driven to advance the crosshead 151 to the mold closing completion position at the set moving speed, thereby advancing the movable platen 120 and bringing the movable mold 820 into contact with the fixed mold 810. The position and moving speed of the crosshead 151 are detected using, for example, the 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.

[0030] Note that the crosshead position detector for detecting the position of the crosshead 151 and the crosshead moving speed detector for detecting the moving speed of the crosshead 151 are not limited to the mold clamping motor encoder 161, and general ones can be used. Also, the movable platen position detector for detecting the position of the movable platen 120 and the movable platen moving speed detector for detecting the moving speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and general ones can be used.

[0031] In the pressure boosting process, the mold clamping motor 160 is further driven to advance the crosshead 151 from the mold closing completion position to the mold clamping position to generate a mold clamping force.

[0032] 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 boosting process is maintained. In the mold clamping process, a cavity space 801 (see FIG. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with a liquid molding material. The filled molding material is solidified to obtain a molded product.

[0033] The number of cavity spaces 801 may be one or plural. In the latter case, a plurality of molded products can be obtained simultaneously. An insert material may be arranged in a part of the cavity space 801, and a molding material may be filled in another part of the cavity space 801. A molded product in which the insert material and the molding material are integrated can be obtained.

[0034] In the mold release process, the mold clamping motor 160 is driven to retract the crosshead 151 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.

[0035] In the mold opening process, the mold clamping motor 160 is driven to retract the crosshead 151 from the mold opening start position to the mold opening completion position at a set moving speed, thereby retracting the movable platen 120 and separating the movable mold 820 from the fixed mold 810. Then, the ejector device 200 ejects the molded product from the movable mold 820.

[0036] The setting conditions in the mold closing process, the pressure boosting process, and the mold clamping process are set together as a series of setting conditions. For example, the moving speed and position of the crosshead 151 (including the mold closing start position, the moving 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 boosting process are set together as a series of setting conditions. The mold closing start position, the moving speed switching position, the mold closing completion position, and the mold clamping position are arranged in this order from the rear to the front and represent the start point and the end point of the section where the moving speed is set. The moving speed is set for each section. The number of moving speed switching positions may be one or plural. The moving speed switching position may not be set. Either only the mold clamping position or only the mold clamping force may be set.

[0037] The setting conditions in the pressure release process and the mold opening process are also set in the same way. For example, the moving speed and position of the crosshead 151 in the pressure release process and the mold opening process (mold opening start position, moving speed switching position, and mold opening completion position) are set together as a series of setting conditions. The mold opening start position, moving speed switching position, and mold opening completion position are arranged in this order from the front to the rear, and represent the start and end points of the section where the moving speed is set. The moving speed is set for each section. The moving speed switching position may be one or more. The moving speed switching position may not be set. The mold opening start position and the mold closing completion position may be the same position. Also, the mold opening completion position and the mold closing start position may be the same position.

[0038] In addition, instead of the moving speed and position of the crosshead 151, etc., the moving speed and position of the movable platen 120, etc. may be set. Also, instead of the position of the crosshead (e.g., mold clamping position) and the position of the movable platen, the mold clamping force may be set.

[0039] 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 ratio is also called the toggle ratio. The toggle ratio changes according to 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 obtained from the position of the crosshead 151. When the link angle θ is 180°, the toggle ratio becomes the maximum.

[0040] When the thickness of the mold device 800 changes due to the replacement of the mold device 800 or the temperature change of the mold device 800, etc., mold thickness adjustment is performed so that a predetermined mold clamping force can be obtained during mold clamping. In the mold thickness adjustment, for example, the interval 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.

[0041] 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. Note that the timing of the mold thickness adjustment is performed, for example, between the end of the molding cycle and the start of the next molding cycle. The mold thickness adjustment mechanism 180 includes, for example, a screw shaft 181 formed at the rear end of the tie bar 140, a screw nut 182 rotatably and non-axially held by the toggle support 130, and a mold thickness adjustment motor 183 that rotates the screw nut 182 screwed onto the screw shaft 181.

[0042] The screw shaft 181 and the 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 a plurality of screw nuts 182 via a rotational driving force transmission unit 185. The plurality of screw nuts 182 can be rotated synchronously. In addition, by changing the transmission path of the rotational driving force transmission unit 185, it is also possible to rotate the plurality of screw nuts 182 individually.

[0043] The rotational driving force transmission unit 185 is composed of, for example, gears. 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 meshing with the plurality of driven gears and the driving gear is rotatably held at the center of the toggle support 130. Note that the rotational driving force transmission unit 185 may be composed of a belt, a pulley, or the like instead of gears.

[0044] The operation of the mold thickness adjustment mechanism 180 is controlled by a 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 the toggle support 130 relative to the tie bar 140 is adjusted, and the distance L between the fixed platen 110 and the toggle support 130 is adjusted. Note that a plurality of mold thickness adjustment mechanisms may be used in combination.

[0045] The interval L is detected using the mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the amount of rotation and the direction of rotation of the mold thickness adjustment motor 183, and sends a signal indicating the detection result to the control device 700. The detection result of the mold thickness adjustment motor encoder 184 is used for monitoring and controlling the position of the toggle support 130 and the interval L. Note that the toggle support position detector for detecting the position of the toggle support 130 and the interval detector for detecting the interval L are not limited to the mold thickness adjustment motor encoder 184, and general ones can be used.

[0046] The mold clamping device 100 may have a mold temperature controller for adjusting the temperature of the mold device 800. The mold device 800 has a flow path for a temperature control medium inside. The mold temperature controller adjusts the temperature of the mold device 800 by adjusting the temperature of the temperature control medium supplied to the flow path of the mold device 800.

[0047] Note that the mold clamping device 100 of the present embodiment is a horizontal type in which the mold opening and closing direction is the horizontal direction, but it may also be a vertical type in which the mold opening and closing direction is the vertical direction.

[0048] Note that the mold clamping device 100 of the present embodiment has a mold clamping motor 160 as a drive unit, but it may have a hydraulic cylinder instead of the mold clamping motor 160. Further, the mold clamping device 100 may have a linear motor for mold opening and closing and an electromagnet for mold clamping.

[0049] (Ejector device) In the description of the ejector device 200, similar to the description of the mold clamping device 100, the moving direction of the movable platen 120 at the time of mold closing (for example, the positive X-axis direction) is defined as the front, and the moving direction of the movable platen 120 at the time of mold opening (for example, the negative X-axis direction) is defined as the rear for explanation.

[0050] The ejector device 200 is attached to the movable platen 120 and moves forward and backward together with the movable platen 120. The ejector device 200 has an ejector rod 210 that protrudes the molded product from the mold device 800 and a drive mechanism 220 that moves the ejector rod 210 in the moving direction (X-axis direction) of the movable platen 120.

[0051] The ejector rod 210 is disposed so as to be able to advance and retract in the through hole of the movable platen 120. The front end portion of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The front end portion of the ejector rod 210 may or may not be connected to the ejector plate 826.

[0052] 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 the linear motion of the ejector rod 210. The motion conversion mechanism includes a screw shaft and a screw nut that engages with the screw shaft. A ball or a roller may be interposed between the screw shaft and the screw nut.

[0053] The ejector device 200 performs a protruding process under the control of the control device 700. In the protruding process, the ejector rod 210 is advanced from the standby position to the protruding position at a set moving speed, whereby the ejector plate 826 is advanced to eject the molded product. Thereafter, the ejector motor is driven to retract the ejector rod 210 at the set moving speed, and the ejector plate 826 is retracted to the original standby position.

[0054] The position and the 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 moving 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.

[0055] (Injection device) In the description of the injection device 300, unlike the description of the mold clamping device 100 and the description of the ejector device 200, the moving direction of the screw 330 during filling (for example, the negative X-axis direction) is defined as the front, and the moving direction of the screw 330 during metering (for example, the positive X-axis direction) is defined as the rear for the description.

[0056] The injection device 300 is installed on the slide base 301, and the slide base 301 is arranged to be movable forward and backward with respect to the injection device frame 920. The injection device 300 is arranged to be movable forward and backward with respect to the mold device 800. The injection device 300 touches the mold device 800 and fills the cavity space 801 in the mold device 800 with the molding material. The injection device 300 includes, for example, a cylinder 310 for heating the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 arranged to be movable forward and backward and rotatable within the cylinder 310, a metering motor 340 for rotating the screw 330, an injection motor 350 for moving the screw 330 forward and backward, and a load detector 360 for detecting the load transmitted between the injection motor 350 and the screw 330.

[0057] The cylinder 310 heats the molding material supplied into it from the supply port 311. The molding material includes, for example, resin and the like. The molding material is formed, for example, in the shape of pellets 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 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.

[0058] 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 detected temperature of the first temperature detector 314 becomes the set temperature.

[0059] 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.

[0060] The screw 330 is rotatably and axially displaceably arranged within the cylinder 310. When the screw 330 is rotated, the molding material is fed forward along the helical groove of the screw 330. While being fed forward, the molding material is gradually melted by the heat from the cylinder 310. As the liquid molding material is fed forward and accumulates at the front of the screw 330 in the front part 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 fills the mold device 800.

[0061] At the front of the screw 330, a backflow prevention ring 331 is axially displaceably attached as a backflow prevention valve that prevents the backflow of the molding material from the front to the back of the screw 330 when the screw 330 is pushed forward.

[0062] 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 relatively retracts with respect to the screw 330 to a closed position (see FIG. 2) that closes the flow path of the molding material. Thereby, the backflow of the molding material accumulated in front of the screw 330 to the back is prevented.

[0063] 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 fed forward along the helical groove of the screw 330 and relatively advances with respect to the screw 330 to an open position (see FIG. 1) that opens the flow path of the molding material. Thereby, the molding material is fed to the front of the screw 330.

[0064] 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.

[0065] Furthermore, the injection device 300 may have a drive source that axially displaces the backflow prevention ring 331 with respect to the screw 330 between the open position and the closed position.

[0066] The metering motor 340 rotates the screw 330. The drive source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump or the like.

[0067] The injection motor 350 moves the screw 330 forward and backward. Between the injection motor 350 and the screw 330, a motion conversion mechanism or the like for converting the rotational motion of the injection motor 350 into the linear motion of the screw 330 is provided. The motion conversion mechanism has, for example, a screw shaft and a screw nut screwed onto the screw shaft. Between the screw shaft and the screw nut, balls, rollers, or the like may be provided. The drive source for moving the screw 330 forward and backward is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder or the like.

[0068] The load detector 360 detects the load transmitted between the injection motor 350 and the screw 330. The detected load is converted into pressure by the control device 700. The load detector 360 is provided in the load transmission path between the injection motor 350 and the screw 330, and detects the load acting on the load detector 360.

[0069] The load detector 360 sends the signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into the pressure acting between the screw 330 and the molding material, and is used for the control and monitoring of the pressure received by the screw 330 from the molding material, the back pressure on the screw 330, the pressure acting from the screw 330 on the molding material, and the like.

[0070] In addition, the pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a general one can be used. For example, a nozzle pressure sensor or an in-mold pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320. The in-mold pressure sensor is installed inside the mold device 800.

[0071] The injection device 300 performs a metering process, a filling process, a holding pressure process, and the like under the control of the control device 700. The filling process and the holding pressure process may be collectively referred to as an injection process.

[0072] In the metering process, 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 accumulates at the front part of the cylinder 310, the screw 330 is retracted. The rotational speed of the screw 330 is detected, for example, using the metering motor encoder 341. The metering motor encoder 341 detects the rotation of the metering motor 340 and sends a signal indicating the detection result to the control device 700. Note that the screw rotational speed detector for detecting the rotational speed of the screw 330 is not limited to the metering motor encoder 341, and a general one can be used.

[0073] In the metering process, in order to limit the sudden retraction of the screw 330, the injection motor 350 may be driven to apply a set back pressure to the screw 330. The back pressure on the screw 330 is detected, for example, using the load detector 360. When the screw 330 retracts to the metering completion position and a predetermined amount of molding material accumulates in front of the screw 330, the metering process is completed.

[0074] The position and rotational speed of the screw 330 in the metering process are set together as a series of set conditions. For example, the metering start position, the rotational speed switching position, and the metering completion position are set. These positions are arranged in this order from the front to the rear, and represent the start point and end point of the section where the rotational speed is set. The rotational speed is set for each section. The rotational speed switching position may be one or a plurality. The rotational speed switching position may not be set. Also, the back pressure is set for each section.

[0075] In the filling process, the injection motor 350 is driven to move the screw 330 forward at a set moving speed, and the liquid molding material accumulated in front of the screw 330 is filled into the cavity space 801 in the mold device 800. The position and moving speed of the screw 330 are detected using, for example, the injection motor encoder 351. The injection motor encoder 351 detects the rotation of the injection motor 350 and sends a signal indicating the detection result to the control device 700. When the position of the screw 330 reaches the set position, the switching from the filling process to the holding pressure process (so-called V / P switching) is performed. The position at which the V / P switching is performed is also called the V / P switching position. The set moving speed of the screw 330 may be changed according to the position and time of the screw 330, etc. [[ID=]2]

[0076] The position and moving speed of the screw 330 in the filling process are set together as a series of set conditions. For example, the filling start position (also called the "injection start position"), the moving speed switching position, and the V / P switching position are set. These positions are arranged in this order from the rear to the front and represent the start and end points of the section where the moving speed is set. The moving speed is set for each section. The moving speed switching position may be one or more. The moving speed switching position may not be set.

[0077] For each section where the moving speed of the screw 330 is set, the upper limit value of the pressure of the screw 330 is set. The pressure of the screw 330 is detected by the load detector 360. When the pressure of the screw 330 is below the set pressure, the screw 330 is advanced at the set moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, for the purpose of mold protection, the screw 330 is advanced at a moving speed slower than the set moving speed so that the pressure of the screw 330 becomes below the set pressure.

[0078] Further, 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 advanced or retracted at a very low speed. Also, the screw position detector for detecting the position of the screw 330 and the screw moving speed detector for detecting the moving speed of the screw 330 are not limited to the injection motor encoder 351, and general ones can be used.

[0079] In the holding pressure process, the injection motor 350 is driven to push the screw 330 forward, 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 molding material remaining in the cylinder 310 is pushed toward the mold device 800. The shortage of the molding material due to the cooling shrinkage in the mold device 800 can be replenished. The holding pressure is detected using, for example, the load detector 360. The set value of the holding pressure may be changed according to the elapsed time from the start of the holding pressure process and the like. A plurality of holding pressures and holding times for holding the holding pressure may be set in the holding pressure process, respectively, and may be set together as a series of setting conditions.

[0080] In the holding pressure process, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and when the holding pressure process is completed, the inlet of the cavity space 801 is blocked by the solidified molding material. This state is called gate sealing, and the backflow of the molding material from the cavity space 801 is prevented. After the holding pressure process, the cooling process is started. In the cooling process, the molding material in the cavity space 801 is solidified. For the purpose of shortening the molding cycle time, the metering process may be performed during the cooling process.

[0081] The injection device 300 of the present embodiment is of the in-line screw type, but it may also be of the pre-plunger type or the like. The injection device of the pre-plunger type supplies the molding material melted in the plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into the mold device. In the plasticizing cylinder, a screw is disposed rotatably and non-axially movable, or a screw is disposed rotatably and axially movable. On the other hand, in the injection cylinder, a plunger is disposed axially movable.

[0082] Further, the injection device 300 of the present embodiment is horizontal with the axial direction of the cylinder 310 being the horizontal direction, but it may be vertical with the axial direction of the cylinder 310 being the vertical direction. 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.

[0083] (Moving device) In the description of the moving device 400, similar to the description of the injection device 300, the moving direction of the screw 330 during filling (for example, the negative X-axis direction) is defined as the front, and the moving direction of the screw 330 during metering (for example, the positive X-axis direction) is defined as the rear for description.

[0084] The moving device 400 moves the injection device 300 forward and backward with respect to the mold device 800. Further, the moving device 400 presses the nozzle 320 against the mold device 800 to generate a nozzle touch pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

[0085] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a pump that can rotate in both directions. 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 to generate hydraulic pressure. Incidentally, the hydraulic pump 410 can also suck the hydraulic fluid from the tank and discharge the hydraulic fluid from one of the first port 411 and the second port 412.

[0086] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 with a rotation direction and a rotational torque according to a control signal from the control device 700. The motor 420 may be an electric motor and may be an electric servo motor.

[0087] The hydraulic cylinder 430 has a cylinder main body 431, a piston 432, and a piston rod 433. The cylinder main body 431 is fixed to the injection device 300. The piston 432 divides the inside of the cylinder main 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.

[0088] 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. By supplying the hydraulic fluid discharged from the first port 411 to the front chamber 435 via the first flow path 401, the injection device 300 is pushed forward. The injection device 300 advances, and the nozzle 320 is pressed against the fixed mold 810. 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.

[0089] 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. By supplying the hydraulic fluid discharged from the second port 412 to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402, the injection device 300 is pushed backward. The injection device 300 retreats, and the nozzle 320 is separated from the fixed mold 810.

[0090] In addition, in this embodiment, the moving device 400 includes the 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 a linear motion of the injection device 300 may be used.

[0091] (Control device) The control device 700 is configured by, for example, a computer, and has a CPU (Central Processing Unit) 701, a storage medium 702 such as a memory, an input interface 703, and an output interface 704 as shown in FIGS. 1 to 2. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. Further, 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.

[0092] The control device 700 repeatedly manufactures molded products by repeatedly performing a metering process, a mold closing process, a pressure boosting process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure releasing process, a mold opening process, a protruding process, and the like. A series of operations for obtaining a molded product, for example, the operations from the start of the metering process to the start of the next metering process, are also called "shots" or "molding cycles". Further, the time required for one shot is also called "molding cycle time" or "cycle time".

[0093] One molding cycle has, for example, a metering process, a mold closing process, a pressure boosting process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure releasing process, a mold opening process, and a protruding process in this order. The order here is the order of the start of each process. The filling process, the pressure holding process, and the cooling process are performed during the mold clamping process. The start of the mold clamping process may coincide with the start of the filling process. The completion of the pressure releasing process coincides with the start of the mold opening process.

[0094] Incidentally, for the purpose of shortening the molding cycle time, a plurality of processes may be performed simultaneously. For example, the metering process may be performed during the cooling process of the previous molding cycle or during the mold clamping process. In this case, the mold closing process may be performed first in the molding cycle. Further, the filling process may be started during the mold closing process. Further, the protruding process may be started during the mold opening process. When an on-off valve for opening and closing the flow path of the nozzle 320 is provided, the mold opening process may be started during the metering process. Even if the mold opening process is started during the metering process, as long as the on-off valve closes the flow path of the nozzle 320, the molding material does not leak from the nozzle 320.

[0095] Furthermore, one molding cycle may have processes other than a metering process, a mold closing process, a pressure boosting process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a pressure releasing process, a mold opening process, and an ejection process.

[0096] For example, after completion of the pressure holding process and before start of the metering process, a pre-metering suck-back process of retracting the screw 330 to a preset metering start position may be performed. The pressure of the molding material accumulated in front of the screw 330 can be reduced, and a sudden retraction of the screw 330 at the start of the metering process can be prevented.

[0097] Also, after completion of the metering process and before start of the filling process, a post-metering suck-back process of retracting the screw 330 to a preset filling start position (also referred to as an "injection start position") may be performed. The pressure of the molding material accumulated in front of the screw 330 can be reduced, and leakage of the molding material from the nozzle 320 before start of the filling process can be prevented.

[0098] The control device 700 is connected to an operation device 750 that receives input operations by the user and a display device 760 that displays a screen. The operation device 750 and the display device 760 may be configured by, for example, a touch panel 770 and integrated. The touch panel 770 as the display device 760 displays a screen under the control of the control device 700. On the screen of the touch panel 770, information such as settings of the injection molding machine 10 and the current state of the injection molding machine 10 may be displayed. Also, on the screen of the touch panel 770, operation units such as buttons and input fields for receiving input operations by the user may be displayed. The touch panel 770 as the operation device 750 detects an input operation on the screen by the user and outputs a signal corresponding to the input operation to the control device 700. Thereby, for example, the user can perform settings (including input of set values) of the injection molding machine 10 and the like by operating the operation unit provided on the screen while checking the information displayed on the screen. Also, by the user operating the operation unit provided on the screen, the operation of the injection molding machine 10 corresponding to the operation unit can be made to be performed. 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. Also, the operation of the injection molding machine 10 may be, for example, the switching of the screen displayed on the touch panel 770 as the display device 760.

[0099] Incidentally, although the operation device 750 and the display device 760 of the present embodiment have been described as being integrated as the touch panel 770, they may be provided independently. Also, a plurality of operation devices 750 may be provided. The operation device 750 and the display device 760 are arranged on the operation side (negative Y-axis direction) of the mold clamping device 100 (more specifically, the fixed platen 110).

[0100] (Temperature Control of Molding Material) Next, with reference to FIG. 3, an example of the components of the control device 700 will be described. Note that each functional block illustrated in FIG. 3 is conceptual, and it is not necessarily physically configured as shown. All or part of each functional block can be functionally or physically distributed and integrated in any unit. Each processing function performed in each functional block can be realized by a program executed by a CPU for all or any part of it, or can be realized as hardware by wired logic.

[0101] The control device 700 includes, for example, a clamping control unit 711, an ejector control unit 712, an injection control unit 713, a metering control unit 714, a temperature control unit 715, and a cooling control unit 716. The clamping control unit 711 controls the clamping device 100 and performs the mold closing process, pressure boosting process, clamping process, pressure releasing process, and mold opening process shown in FIG. 4. The ejector control unit 712 controls the ejector device 200 and performs the protruding process. The injection control unit 713 controls the injection motor 350 of the injection device 300 and performs the injection process. The injection process includes a filling process and a holding pressure process. The injection process is performed during the clamping process. The metering control unit 714 controls the metering motor 340 of the injection device 300 and performs the metering process. The metering process is performed during the cooling process. Details of the temperature control unit 715 and the cooling control unit 716 will be described later.

[0102] The temperature control unit 715 controls the first heater 313 and the second heater 323 of the injection device 300 to control the temperature of the molding material. An example of the configuration of the injection device 300 will be described with reference to FIG. 5. The injection device 300 includes, for example, a cylinder 310, a nozzle 320, a first heater 313, a second heater 323, a screw 330, a metering motor 340, and an injection motor 350.

[0103] The cylinder 310 has a plurality of zones CZ (only one is shown in FIG. 5) along the injection direction (for example, the X-axis direction). In each of the zones CZ, a first heater 313 and a first temperature detector 314 are provided, and a set temperature is set. The temperature control unit 715 controls the first heater 313 so that the detected temperature of the first temperature detector 314 becomes the set temperature. The first heater 313 is provided on the outer periphery of the cylinder 310 and heats the cylinder 310.

[0104] The nozzle 320 is provided at the tip of the cylinder 310. The nozzle 320 is provided separately from the cylinder 310 and attached to the cylinder 310. The nozzle 320 may be detachably attached to the cylinder 310. The nozzle 320 has an outer diameter smaller than that of the cylinder 310. Although not shown, an adapter for relaying between the cylinder 310 and the nozzle 320 may be provided between the cylinder 310 and the nozzle 320. A second heater 323 is provided on the outer periphery of the nozzle 320 and heats the nozzle 320.

[0105] The nozzle 320 has a plurality of zones NZ1 to NZ4 along the injection direction (for example, the X-axis direction). In each of the zones NZ1 to NZ4, a second heater 323 and a second temperature detector 324 are provided, and a set temperature is set. An insulating portion 328 that blocks heat transfer between two adjacent zones (for example, zones NZ1 and NZ2) may be provided between two adjacent zones. The insulating portion 328 includes, for example, a groove. The temperature control unit 715 controls the second heater 323 so that the detected temperature of the second temperature detector 324 becomes the set temperature. Note that, as will be described later, the number of the second heaters 323 may be one.

[0106] The nozzle 320 has, for example, a nozzle body 321 provided with a second heater 323, and a nozzle tip 322 provided at the tip of the nozzle body 321. A plurality of second heaters 323 may be provided at intervals in the injection direction on the outer periphery of the nozzle body 321. Also, a heat insulating portion 328 may be provided between the plurality of second heaters 323. The nozzle tip 322 has an outer diameter smaller than that of the nozzle body 321. The nozzle tip 322 touches the mold device 800 and injects the molding material into the mold device 800.

[0107] The screw 330 is an injection member that injects the molding material inside the cylinder 310 and the nozzle 320 from the nozzle 320. Note that the injection member is not limited to the screw 330 and may be, for example, a plunger. The injection member is provided so as to be able to advance and retreat inside the cylinder 310. Molten molding material is stored in front of the injection member.

[0108] The injection motor 350 is a drive source for advancing and retreating the injection member. The injection motor 350 injects the molten molding material stored in front of the screw 330 from the nozzle 320, for example, by advancing the screw 330. The drive source for advancing and retreating the injection member is not limited to the injection motor 350 and may be, for example, a hydraulic cylinder.

[0109] The injection device 300 manufactures the molded product 20 (see FIG. 7) by filling the molten molding material into the cavity space 801 (see FIG. 2) of the mold device 800 and solidifying the filled molding material. The shape and dimensions of the molded product 20 are determined by the shape and dimensions of the cavity space 801. By replacing the mold device 800, it is possible to change the dimensions and shape of the molded product 20.

[0110] The molding material flows into the cavity space 801 from the entrance of the cavity space 801, is cooled from the point where it contacts the wall surface of the cavity space 801, and forms, for example, the skin layer 21. The thickness of the skin layer 21 is, for example, 0.05 mm to 1 mm. The thickness of the skin layer 21 is measured, for example, by cross-sectional observation using an optical microscope.

[0111] While forming the skin layer 21, the molding material forms the core layer 22 filled inside the skin layer 21. After the cavity space 801 is filled with the molding material, a seal layer 23 that closes the inlet of the cavity space 801 is formed. As a result, a molded product 20 including the skin layer 21, the core layer 22, and the seal layer 23 is obtained.

[0112] Conventionally, when the heating temperature of the nozzle 320 is set low, the fluidity of the molding material decreases, and there has been a problem that the filling property of the molding material with respect to the mold apparatus 800 and the shape transferability from the mold apparatus 800 to the molded product 20 decrease. On the other hand, when the heating temperature of the nozzle 320 is set high, it takes time to solidify the molten molding material, and there has been a problem that the molding cycle time becomes long.

[0113] The temperature control unit 715 controls the temperature of the molding material corresponding to the skin layer 21 to be higher than the temperature of the molding material corresponding to the core layer 22 at the start of the injection process. Since the molding material corresponding to the skin layer 21 flows into the cavity space 801 earlier than the molding material corresponding to the core layer 22, it is located in the front in the injection direction (negative X-axis direction). At the start of the injection process, the molding material corresponding to the skin layer 21 is accommodated in the nozzle 320, and the molding material corresponding to the core layer 22 is accommodated in the cylinder 310.

[0114] The temperature control unit 715 controls, for example, the temperature of at least a part of the molding material in the nozzle 320 to be higher than the temperature of the molding material in the cylinder 310 at the start of the injection process. Specifically, for example, as shown in FIG. 6, the temperature control unit 715 controls the temperature of at least a part of the second heaters 323 (for example, the temperatures of the zones NZ2, NZ3, NZ4) to be higher than the temperature of the first heater 313 (for example, the temperature of the zone CZ).

[0115] When a plurality of first heaters 313 are provided in the axial direction of the cylinder 310, among the plurality of first heaters 313, the temperature of at least a part of the second heaters 323 is controlled to be higher than the temperature of the first heater 313 closest to the nozzle 320. For two adjacent second heaters 323, the temperature of the second heater 323 on the front side (negative X-axis direction) of the injection direction is controlled to be equal to or higher than the temperature of the second heater 323 on the rear side (positive X-axis direction) of the injection direction (see Fig. 6).

[0116] As described above, the temperature control unit 715 controls the temperature of the molding material corresponding to the skin layer 21 to be relatively high at the start of the injection process. The temperature of the molding material corresponding to the skin layer 21 at the start of the injection process is, for example, (Tg + 100)°C or higher and (Tg + 200)°C or lower. Here, Tg is the glass transition temperature of the resin that is the molding material. Therefore, the temperature of at least a part of the second heaters 323 is, for example, (Tg + 100)°C or higher and (Tg + 200)°C or lower. The higher the temperature of the molding material corresponding to the skin layer 21, the smoother the molding material flows along the wall surface of the cavity space 801. Thus, the filling property of the molding material with respect to the mold device 800 and the shape transferability from the mold device 800 to the molded product 20 can be improved.

[0117] Also, as described above, the temperature control unit 715 controls the temperature of the molding material corresponding to the core layer 22 to be low at the start of the injection process. The temperature of the molding material corresponding to the core layer 22 at the start of the injection process is, for example, (Tg + 60)°C or higher and (Tg + 130)°C or lower. Therefore, the temperature of the first heater 313 closest to the nozzle 320 is, for example, (Tg + 60)°C or higher and (Tg + 130)°C or lower. The lower the temperature of the molding material, the faster the molding material solidifies in a short time. Thus, the molding cycle time can be shortened.

[0118] The temperature control unit 715 can set the temperature of the first heater 313 lower than before by making the temperature of at least a part of the second heater 323 higher than the temperature of the first heater 313, and can reduce the power consumption of the first heater 313 and the second heater 323. The ratio of the power consumed by the first heater 313 and the second heater 323 in the total power consumed by the injection molding machine 10 is high, for example, 40% - 80%. Therefore, by reducing the power consumed by the first heater 313 and the second heater 323, the power consumed by the entire injection molding machine 10 can be sufficiently reduced.

[0119] The temperature control unit 715 may change the volume of the molding material in the nozzle 320, which is controlled to a temperature higher than the temperature of the molding material in the cylinder 310 at the start of the injection process, according to the volume of the skin layer 21. The volume of the skin layer 21 is determined by the shape and dimensions of the cavity space 801 of the mold device 800, and more specifically, by the shape and dimensions of the wall surface of the cavity space 801. It becomes possible to cope with the replacement of the mold device 800.

[0120] For example, as shown in FIG. 5, when a plurality of second heaters 323 are provided along the injection direction, the temperature control unit 715 changes the number of second heaters 323 that are controlled to a temperature higher than the temperature of the first heater 313 according to the volume of the skin layer 21. The temperature control unit 715 changes the number of zones among the zones NZ1 - NZ4 that have a temperature higher than the temperature of the zone CZ according to the volume of the skin layer 21. The larger the volume of the skin layer 21, the more the number of zones with a higher temperature increases.

[0121] Next, with reference to FIGS. 8 and 9, a modified example of the injection device 300 will be described. As shown in FIG. 8, the number of the second heaters 323 may be one. Also in this case, as shown in FIG. 9, the temperature control unit 715 controls the temperature of the second heater 323 (for example, the temperature of the zone NZ1) to be higher than the temperature of the first heater 313 (for example, the temperature of the zone CZ).

[0122] The injection control unit 713 may control the volume of the molding material in the nozzle 320, which is controlled to a temperature higher than the temperature of the molding material in the cylinder 310, by controlling the position of the screw 330 inserted into the nozzle 320 at the completion of the injection process as shown in FIG. 8(A).

[0123] As shown in FIG. 8(A), at the completion of the injection process, the tip of the screw 330 is inserted into the zone NZ1, which is heated to a temperature higher than the zone CZ. Then, as shown in FIG. 8(B), by the completion of the metering process, the tip of the screw 330 is withdrawn from the zone NZ1.

[0124] In FIG. 8(B), the region A is a part of the zone NZ1, and from the completion of the injection process to the completion of the metering process, the tip of the screw 330 is withdrawn, and the molding material flows into the region instead of the screw 330. Relatively cold molding material flows into the region A. If the molding cycle time is short, the temperature of the molding material in the region A remains cold at the start of the next injection process.

[0125] Therefore, by controlling the position of the screw 330 inserted into the nozzle 320 at the completion of the injection process, it is possible to control the volume of the molding material in the nozzle 320, which is controlled to a temperature higher than the temperature of the molding material in the cylinder 310, at the start of the next injection process. This control is also applicable when the number of the second heaters 323 is plural.

[0126] The injection control unit 713 may change the position of the screw 330 inserted into the nozzle 320 at the completion of the injection process according to the volume of the skin layer 21. Thereby, it is possible to cope with the replacement of the mold device 800. When the mold device 800 is replaced, the shape and dimensions of the cavity space 801 change, and the volume of the skin layer 21 changes.

[0127] Next, with reference to FIGS. 4 and 10, an example of the cooling control unit 716 shown in FIG. 3 will be described. The cooling control unit 716 controls the cooler 325 to cool the tip of the nozzle 320. As shown in FIG. 10, the cooler 325 is provided at the tip of the nozzle 320, specifically, for example, on the outer periphery of the nozzle tip 322.

[0128] The cooler 325 has, for example, a cooling pipe 326 and a refrigerant supplier 327 that supplies refrigerant to the cooling pipe 326. As the refrigerant, a gas such as air or a liquid such as water is used. The cooling pipe 326 is wound around the outer periphery of the nozzle tip 322 in a coil shape, but may be formed in a cylindrical shape along the injection direction.

[0129] The refrigerant supplier 327 supplies the refrigerant temperature-controlled to a predetermined temperature to the cooling pipe 326 under the control of the cooling control unit 716. The refrigerant cools the nozzle tip 322 by absorbing heat from the nozzle tip 322 while flowing through the cooling pipe 326. The refrigerant supplier 327 starts cooling the nozzle tip 322 by starting the supply of the refrigerant to the cooling pipe 326. The refrigerant supplier 327 stops cooling the nozzle tip 322 by stopping the supply of the refrigerant to the cooling pipe 326.

[0130] Note that the cooler 325 may include a Peltier element and a current supplier instead of the cooling pipe 326 and the refrigerant supplier 327. The current supplier starts cooling the nozzle tip 322 by starting the supply of current to the Peltier element. The current supplier stops cooling the nozzle tip 322 by stopping the supply of current to the Peltier element. Note that the Peltier element can also heat the nozzle tip 322 by reversing the direction of the current.

[0131] The cooler 325 cools the nozzle tip 322 to such an extent that so-called stringing can be prevented at the start of the mold opening process. Stringing is a phenomenon in which the molding material that has not completely solidified at the boundary between the nozzle tip 322 and the mold device 800 extends in a thread shape due to mold opening. Stringing can cause appearance defects in the molded product 20 or damage to the mold device 800.

[0132] If the cooler 325 continues to cool the nozzle tip 322 during the molding cycle, the temperature of the molding material inside the nozzle body 321 will be low at the start of the injection process. Therefore, the cooling control unit 716 may cool the tip of the nozzle 320 only for part of the molding cycle, as shown in FIG.

[0133] The cooling control unit 716 starts cooling the nozzle tip 322 before the mold opening process starts so that the nozzle tip 322 can be cooled to a degree that prevents stringiness at the start of the mold opening process. The timing for starting cooling the nozzle tip is, for example, between the start of the mold closing process and the start of the injection process.

[0134] Furthermore, at the start of the next injection process, the cooling control unit 716 stops cooling of the nozzle tip at a desired timing in order to increase the temperature of the molding material inside the nozzle body 321. The timing for stopping cooling of the nozzle tip is, for example, between the completion of the injection process and the completion of the mold opening process, and preferably between the completion of the injection process and the start of the mold opening process.

[0135] Although the embodiments of the injection molding machine control method and injection molding machine control device according to the present invention have been described above, the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These changes also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0136] 10 injection molding machine 20 Molded products 21 Skin layer 22 Core layer 310 cylinder 313 1st heater 320 nozzle 323 Second heater 330 Screw (injection member) 350 Injection motor (drive source) 700 control device 800 Die Set

Claims

A control method for controlling an injection molding machine that forms a molded product including a skin layer and a core layer in the mold device by injecting a molding material from a nozzle provided at the tip of a cylinder, comprising: At the start of the injection process, controlling the temperature of the molding material corresponding to the skin layer in the nozzle to be higher than the temperature of the molding material corresponding to the core layer in the cylinder. A control method for an injection molding machine.

2. By controlling the position of the injection member inserted into the nozzle at the end of the injection process, controlling the volume of the molding material in the nozzle that is controlled to a temperature higher than the temperature of the molding material in the cylinder. The control method for an injection molding machine according to claim 1.

3. Changing the volume of the molding material in the nozzle that is controlled to a temperature higher than the temperature of the molding material in the cylinder at the start of the injection process according to the volume of the skin layer. The control method for an injection molding machine according to claim 1.

4. A plurality of second heaters are provided in the nozzle along the injection direction. A first heater is provided in the cylinder. Changing the number of the second heaters controlled to a temperature higher than the temperature of the first heater according to the volume of the skin layer. The control method for an injection molding machine according to claim 3.

5. Changing the position of the injection member inserted into the nozzle at the end of the injection process according to the volume of the skin layer. The control method for an injection molding machine according to claim 3 or 4.

6. A control device for controlling an injection molding machine that forms a molded product including a skin layer and a core layer in the mold device by injecting a molding material from a nozzle provided at the tip of a cylinder, comprising: At the start of the injection process, having a temperature control unit that controls the temperature of the molding material corresponding to the skin layer in the nozzle to be higher than the temperature of the molding material corresponding to the core layer in the cylinder. A control device for an injection molding machine.

7. Comprising a cylinder, a nozzle provided at the tip of the cylinder, a first heater for heating the cylinder, and a second heater for heating the nozzle. By injecting a molding material from the nozzle into a mold device, it is a control device for controlling an injection molding machine that forms a molded product including a skin layer and a core layer in the mold device, A temperature control unit that controls the temperature of at least a part of the second heaters to be higher than the temperature of the first heater, A cooling control unit that controls a cooler provided at the tip of the nozzle. having, The cooling control unit is a control device for an injection molding machine that cools the tip of the nozzle only during a part of the molding cycle. **Claim 8** The control device for an injection molding machine according to claim 7, further comprising an injection control unit that controls the position of an injection member inserted into the nozzle at the completion of the injection process.

Images