Injection molding machine and manufacturing method of molded product

Abstract

To provide an injection molding machine capable of achieving high transfer molding and suppressing stringiness.SOLUTION: There is provided an injection molding machine 10 comprising: a clamping device 100 that closes, pressurizes, clamps, de-pressurizes, and opens a mold device 800; an injection device 300 that injects a molding material into the mold device 800; and a control device 700 that controls the clamping device 100 and the injection device 300. The injection device 300 includes: a nozzle 320 that forms a flow path through which the molding material flows inside; and a cooling unit that cools the nozzle 320. The control device 700 performs first cooling in which the nozzle 320 is cooled by the cooling unit after the start of mold clamping and before the start of mold opening, and second cooling in which the nozzle 320 is cooled by the cooling unit after the start of mold opening and before the completion of mold opening. Furthermore, the control device 700 stops supply of a refrigerant to the cooling unit or reduces a flow rate between the first cooling and the second cooling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an injection molding machine and a method for manufacturing a molded product. [Background technology]

[0002] Conventionally, there has been known an injection molding apparatus that performs injection molding without problems such as stringiness by cooling the tip of the nozzle that injects molten resin (see Patent Document 1 below). The injection molding apparatus described in Patent Document 1 has a nozzle, a flow path, a valve pin, and a nozzle cooling means.

[0003] The nozzle injects molten resin into a cavity formed by relatively approaching molds. The flow path guides the molten resin to the tip of the nozzle. The valve pin is inserted into the nozzle and opens and closes the tip of the nozzle by reciprocating along the insertion direction. The nozzle cooling means guides a portion of the working medium for opening and closing the valve pin to the tip of the nozzle.

[0004] This conventional injection molding device sends cooling medium to the tip of the nozzle in synchronization with the start of injection of molten resin, and stops sending cooling medium in synchronization with the end of injection of molten resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-337187 Summary of the Invention [Problem to be solved by the invention]

[0006] To achieve high-transfer molding, in which the shape of the mold cavity is transferred with high precision to the molded product produced by the injection molding machine, it is necessary to set the molten resin temperature high. However, in the conventional injection molding machine, the supply of cooling medium is stopped when the injection of the molten resin is completed, so if the set temperature of the molten resin is increased, the temperature at the tip of the nozzle increases after the injection of the molten resin is completed, which may cause stringing when the mold is opened.

[0007] The present disclosure provides an injection molding machine that can achieve high transfer molding and suppress stringing, and a method for manufacturing a molded product. [Means for solving the problem]

[0008] One aspect of the present disclosure provides an injection molding machine comprising: a clamping device that closes, pressurizes, clamps, depressurizes, and opens a mold device; an injection device that injects a molding material into the mold device; and a control device that controls the clamping device and the injection device, wherein the injection device includes a nozzle that forms a flow path therein through which the molding material flows, and a cooling unit that cools the nozzle, and the control device performs a first cooling step in which the cooling unit cools the nozzle after the start of clamping and before the start of mold opening, and a second cooling step in which the cooling unit cools the nozzle after the start of mold opening and before the completion of mold opening, and stops or reduces the flow rate of refrigerant to the cooling unit between the first cooling step and the second cooling step.

[0009] Another aspect of the present disclosure provides a method for manufacturing a molded product, which includes a metering step, a mold closing step, a pressurization step, a mold clamping step, a filling step, a pressure holding step, a cooling step, a depressurization step, a mold opening step, and an ejection step, and which includes a first cooling step of cooling the nozzle that injected the molding material in the filling step after the start of the mold clamping step and before the start of the mold opening step, a second cooling step of cooling the nozzle after the start of the mold opening step and before the completion of the mold opening step, and a step of stopping or reducing the flow rate of the refrigerant supply to a cooling section that cools the nozzle between the first cooling step and the second cooling step. [Effects of the Invention]

[0010] According to the above aspects of the present disclosure, it is possible to provide an injection molding machine and a method for manufacturing a molded product that can achieve high transfer molding and suppress stringing. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 10 is a diagram showing a state when mold opening of the injection molding machine is completed. [Figure 2] FIG. 2 is a diagram showing a state in which the injection molding machine is clamped. [Figure 3] FIG. 2 is a cross-sectional view showing an example of an injection device. [Figure 4] 1 is a time chart showing steps included in a method for manufacturing a molded product. [Figure 5] FIG. 2 is a flow diagram illustrating a first cooling step and a second cooling step of the nozzle. [Figure 6] FIG. 10 is a cross-sectional view showing the state of the nozzle before mold opening begins. [Figure 7] 4 is a graph showing the flow rates of the refrigerant in the first cooling step and the second cooling step. [Figure 8] FIG. 10 is a cross-sectional view showing the state of the nozzle after mold opening has started. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of an injection molding machine and a method for manufacturing a molded product according to the present disclosure will be described with reference to the drawings. The embodiments described below are illustrative and do not limit the invention. Not all features and combinations thereof in the embodiments of the present disclosure are necessarily essential to the invention. In addition, identical or corresponding components in each drawing are designated by identical or corresponding reference numerals, and redundant description may be omitted.

[0013] (injection molding machine) Fig. 1 is a diagram showing a state of an injection molding machine according to an embodiment of the present disclosure when mold opening is completed. Fig. 2 is a diagram showing a state of the injection molding machine according to the embodiment of Fig. 1 when mold clamping is performed. In this specification, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction represent horizontal directions, and the Z-axis direction represents vertical directions. When the mold clamping device 100 is of a horizontal type, the X-axis direction is the mold opening / closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side of the Y-axis direction is called the operating side, and the positive side of the Y-axis direction is called the counter-operating side.

[0014] As shown in FIGS. 1 and 2 , the injection molding machine 10 includes a mold clamping unit 100 that opens and closes a mold apparatus 800, an ejector unit 200 that ejects a molded product molded by the mold apparatus 800, an injection unit 300 that injects molding material into the mold apparatus 800, a moving unit 400 that moves the injection unit 300 forward and backward relative to the mold apparatus 800, a control unit 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 unit frame 910 that supports the mold clamping unit 10 and an injection unit frame 920 that supports the injection unit 300. The mold clamping unit frame 910 and the injection unit frame 920 are each installed on the floor 2 via leveling adjusters 930. The control unit 700 is disposed in the internal space of the injection unit frame 920. Each component of the injection molding machine 10 will be described below.

[0015] (mold clamping device) In the description of the mold clamping unit 100, the moving direction of the movable platen 120 during mold closing (for example, the positive X-axis direction) is defined as the front, and the moving direction of the movable platen 120 during mold opening (for example, the negative X-axis direction) is defined as the rear.

[0016] The mold clamping device 100 performs mold closing, pressure increase, mold clamping, depressurization, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a movable mold 820.

[0017] The mold clamping unit 100 is, for example, a horizontal type, and the mold opening and closing direction is horizontal. The mold clamping unit 100 has a fixed platen 110 to which a fixed mold 810 is attached, a movable platen 120 to which a movable mold 820 is attached, and a movement mechanism 102 that moves the movable platen 120 relative to the fixed platen 110 in the mold opening and closing direction.

[0018] The stationary platen 110 is fixed to the mold clamping unit frame 910. A stationary mold 810 is attached to the surface of the stationary platen 110 that faces the movable platen 120.

[0019] The movable platen 120 is disposed so as to be movable in the mold opening / closing direction relative to the mold clamping unit frame 910. A guide 101 for guiding the movable platen 120 is installed on the mold clamping unit frame 910. A movable mold 820 is attached to the surface of the movable platen 120 facing the fixed platen 110.

[0020] The moving mechanism 102 moves the movable platen 120 forward and backward relative to the fixed platen 110, thereby performing mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold apparatus 800. The moving mechanism 102 has a toggle support 130 arranged at a distance from the fixed platen 110, tie bars 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 relative to the toggle support 130, a mold clamping motor 160 that operates the toggle mechanism 150, a motion conversion mechanism 170 that converts the rotational motion of the mold clamping motor 160 into linear motion, and a mold thickness adjustment mechanism 180 that adjusts the distance between the fixed platen 110 and the toggle support 130.

[0021] The toggle support 130 is disposed at a distance from the fixed platen 110 and is placed on the mold clamping unit frame 910 so as to be freely movable in the mold opening and closing direction. The toggle support 130 may be disposed so as to be freely movable along a guide laid on the mold clamping unit frame 910. The guide of the toggle support 130 may be the same as the guide 101 of the movable platen 120.

[0022] In this embodiment, the fixed platen 110 is fixed to the mold clamping unit frame 910, and the toggle support 130 is arranged to be movable in the mold opening / closing direction relative to the mold clamping unit frame 910. Note that the toggle support 130 may be fixed to the mold clamping unit frame 910, and the fixed platen 110 may be arranged to be movable in the mold opening / closing direction relative to the mold clamping unit frame 910.

[0023] The tie bars 140 connect the fixed platen 110 and the toggle support 130 at an interval L in the mold opening / closing direction. A plurality of tie bars 140 (for example, four) may be used. The plurality of tie bars 140 are arranged parallel to the mold opening / closing direction and extend according to the mold clamping force. At least one tie bar 140 may be provided with a tie bar strain detector 141 that detects strain in 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 to detect the mold clamping force, etc.

[0024] In this embodiment, the tie bar strain detector 141 is used as the mold clamping force detector that detects 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 capacitance type, a hydraulic type, an electromagnetic type, or the like, and the attachment position thereof is also not limited to the tie bar 140.

[0025] 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 has a crosshead 151 that moves in the mold opening / closing direction and a pair of link groups that bend and extend with 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 connected to bendable and extendable by a pin or the like. The first link 152 is attached to the movable platen 120 by a pin or the like so that it can swing. The second link 153 is attached to the toggle support 130 by a pin or the like so that it can swing. The second link 153 is attached to the crosshead 151 via a third link 154. When the crosshead 151 advances or retreats relative to the toggle support 130, the first link 152 and the second link 153 bend and extend, and the movable platen 120 advances or retreats relative to the toggle support 130.

[0026] The configuration of the toggle mechanism 150 is not limited to the configuration shown in Figures 1 and 2. For example, although each link group has five nodes in Figures 1 and 2, it may have four nodes, and one end of the third link 154 may be connected to the node between the first link 152 and the second link 153.

[0027] The mold clamping motor 160 is attached to the toggle support 130 and operates the toggle mechanism 150. The mold clamping motor 160 moves the crosshead 151 forward and backward relative to the toggle support 130, thereby bending and extending the first link 152 and the second link 153 and moving the movable platen 120 forward and backward relative to the toggle support 130. The mold clamping motor 160 is directly connected to the motion conversion mechanism 170, but may also be connected to the motion conversion mechanism 170 via a belt, a pulley, or the like.

[0028] 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 screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0029] The mold clamping unit 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure reducing process, a mold opening process, and the like under the control of the control device 700.

[0030] In the mold closing process, the mold clamping motor 160 is driven to move the crosshead 151 forward at a set movement speed to a mold closing completion position, thereby moving the movable platen 120 forward and bringing the movable mold 820 into contact with the fixed mold 810. The position and movement speed of the crosshead 151 are detected using, for example, a mold clamping motor encoder 161. The mold clamping motor encoder 161 detects the rotation of the mold clamping motor 160 and sends a signal indicating the detection result to the control device 700.

[0031] The crosshead position detector that detects the position of the crosshead 151 and the crosshead movement speed detector that detects the movement speed of the crosshead 151 are not limited to the mold clamping motor encoder 161, and general types can be used. Furthermore, the movable platen position detector that detects the position of the movable platen 120 and the movable platen movement speed detector that detects the movement speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and general types can be used.

[0032] In the pressure increasing step, the mold clamping motor 160 is further driven to move the crosshead 151 further forward from the mold closing completion position to the mold clamping position, thereby generating a mold clamping force.

[0033] 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 increase process is maintained. In the mold clamping process, a cavity space 801 (see FIG. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with liquid molding material. The filled molding material is solidified to obtain a molded product.

[0034] The number of cavity spaces 801 may be one or more. In the latter case, multiple molded products are obtained at the same time. An insert material may be placed in a part of the cavity space 801, and the molding material may be filled in another part of the cavity space 801. This results in a molded product in which the insert material and the molding material are integrated.

[0035] In the depressurization process, the mold clamping motor 160 is driven to move the crosshead 151 back from the mold clamping position to the mold opening start position, thereby moving the movable platen 120 back and reducing the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

[0036] In the mold opening process, the mold clamping motor 160 is driven to move the crosshead 151 backward at a set moving speed from the mold opening start position to the mold opening completion position, thereby moving the movable platen 120 backward and separating the movable mold 820 from the fixed mold 810. Thereafter, the ejector unit 200 ejects the molded product from the movable mold 820.

[0037] The setting conditions for the mold closing process, pressure increase process, and mold clamping process are set together as a series of setting conditions. For example, the movement speed and position of the crosshead 151 in the mold closing process and pressure increase process (including the mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position), and the mold clamping force are set together as a series of setting conditions. The mold closing start position, movement speed switching position, mold closing completion position, and mold clamping position are arranged in this order from the rear side to the front, and represent the start and end points of the section for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set. Only one of the mold clamping position and the mold clamping force may be set.

[0038] The setting conditions for the depressurization process and mold opening process are also set in a similar manner. For example, the movement speed and position of the crosshead 151 in the depressurization process and mold opening process (mold opening start position, movement speed switching position, and mold opening completion position) are set together as a series of setting conditions. The mold opening start position, movement 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 for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set. The mold opening start position and the mold closing completion position may be the same position. Furthermore, the mold opening completion position and the mold closing start position may be the same position.

[0039] It should be noted that the moving speed and position of the movable platen 120 may be set instead of the moving speed and position of the crosshead 151. Furthermore, the clamping force may be set instead of the position of the crosshead (e.g., clamping position) or the position of the movable platen.

[0040] The toggle mechanism 150 amplifies the driving force of the mold clamping motor 160 and transmits it to the movable platen 120. The amplification factor is also called the toggle factor. The toggle factor changes depending on the angle θ between the first link 152 and the second link 153 (hereinafter also referred to as the "link angle θ"). The link angle θ is determined from the position of the crosshead 151. When the link angle θ becomes 180°, the toggle factor becomes maximum.

[0041] When the thickness of the mold device 800 changes due to replacement of the mold device 800 or a temperature change in the mold device 800, a mold thickness adjustment is performed so that a predetermined clamping force is obtained during mold clamping. In mold thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle support 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the time of mold touch when the movable mold 820 touches the fixed mold 810.

[0042] The mold clamping unit 100 has a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the mold thickness by adjusting the distance L between the fixed platen 110 and the toggle support 130. The mold thickness adjustment is performed, for example, between the end of a molding cycle and the start of the next molding cycle. The mold thickness adjustment mechanism 180 has, for example, a screw shaft 181 formed at the rear end of the tie bar 140, a screw nut 182 held rotatably and immovably by the toggle support 130, and a mold thickness adjustment motor 183 that rotates the screw nut 182 that is threaded onto the screw shaft 181.

[0043] A screw shaft 181 and a screw nut 182 are provided for each tie bar 140. The rotational driving force of the mold thickness adjustment motor 183 may be transmitted to the plurality of screw nuts 182 via a rotational driving force transmission unit 185. The plurality of screw nuts 182 can be rotated synchronously. Note that by changing the transmission path of the rotational driving force transmission unit 185, the plurality of screw nuts 182 can also be rotated individually.

[0044] The rotational drive 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, and a drive gear is attached to the output shaft of the mold thickness adjustment motor 183. Also, an intermediate gear that meshes with the multiple driven gears and drive gear is rotatably held in the center of the toggle support 130. Note that the rotational drive force transmission unit 185 may be composed of a belt, a pulley, or the like instead of gears.

[0045] The operation of the mold thickness adjustment mechanism 180 is controlled by a control device 700. The control device 700 drives a 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.

[0046] The distance L is detected using a mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the amount and 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 to monitor and control the position of the toggle support 130 and the distance L. Note that the toggle support position detector that detects the position of the toggle support 130 and the distance detector that detects the distance L are not limited to the mold thickness adjustment motor encoder 184, and general detectors can be used.

[0047] The mold clamping unit 100 may have a mold temperature regulator that regulates the temperature of the mold device 800. The mold device 800 has a flow path for a temperature regulation medium inside. The mold temperature regulator regulates the temperature of the mold device 800 by regulating the temperature of the temperature regulation medium supplied to the flow path of the mold device 800.

[0048] The mold clamping unit 100 of this embodiment is a horizontal type in which the mold opening and closing direction is horizontal, but it may also be a vertical type in which the mold opening and closing direction is vertical.

[0049] Furthermore, the mold clamping unit 100 of this embodiment has a mold clamping motor 160 as a drive unit, but may have a hydraulic cylinder instead of the mold clamping motor 160. Furthermore, the mold clamping unit 100 may have a linear motor for opening and closing the mold, and an electromagnet for mold clamping.

[0050] (Ejector device) In describing the ejector device 200, similar to the description of the mold clamping device 100, the direction of movement of the movable platen 120 when the mold is closed (e.g., the positive direction of the X-axis) is defined as the front, and the direction of movement of the movable platen 120 when the mold is opened (e.g., the negative direction of the X-axis) is defined as the rear.

[0051] The ejector unit 200 is attached to the movable platen 120 and moves forward and backward together with the movable platen 120. The ejector unit 200 has an ejector rod 210 that ejects a molded product from the mold device 800, and a drive mechanism 220 that moves the ejector rod 210 in the movement direction of the movable platen 120 (X-axis direction).

[0052] The ejector rod 210 is arranged so as to be able to move forward and backward in a through-hole of the movable platen 120. The front end of the ejector rod 210 contacts an ejector plate 826 of the movable mold 820. The front end of the ejector rod 210 may or may not be connected to the ejector plate 826.

[0053] 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 screws onto the screw shaft. A ball or roller may be interposed between the screw shaft and the screw nut.

[0054] The ejector unit 200 performs an ejection process under the control of the control unit 700. In the ejection process, the ejector rod 210 advances from the standby position to the ejection position at a set moving speed, thereby advancing the ejector plate 826 and ejecting 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.

[0055] The position and movement speed of the ejector rod 210 are detected using, for example, an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and sends a signal indicating the detection result to the control device 700. Note that the ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod movement speed detector that detects the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and general types can be used.

[0056] (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 movement direction of the screw 330 during filling (e.g., the negative X-axis direction) is described as the front, and the movement direction of the screw 330 during metering (e.g., the positive X-axis direction) is described as the rear.

[0057] The injection unit 300 is mounted on a slide base 301, and the slide base 301 is disposed so as to be able to move forward and backward relative to the injection unit frame 920. The injection unit 300 is disposed so as to be able to move forward and backward relative to the mold unit 800. The injection unit 300 touches the mold unit 800 and fills a cavity space 801 in the mold unit 800 with a molding material. The injection unit 300 includes, for example, a cylinder 310 that heats the molding material, a nozzle 320 provided at the front end of the cylinder 310, a screw 330 that is disposed so as to be able to move forward and backward and to be able to rotate within the cylinder 310, a metering motor 340 that rotates the screw 330, an injection motor 350 that moves the screw 330 forward and backward, and a load detector 360 that detects a load transmitted between the injection motor 350 and the screw 330.

[0058] Cylinder 310 heats the molding material supplied to the interior through supply port 311. The molding material includes, for example, resin. The molding material is formed, for example, in the form of pellets and supplied to supply port 311 in a solid state. Supply port 311 is formed at the rear of cylinder 310. A cooler 312, such as a water-cooled cylinder, is provided on the outer periphery of the rear of cylinder 310. A first heater 313, such as a band heater, and a first temperature detector 314 are provided on the outer periphery of cylinder 310, ahead of cooler 312.

[0059] Cylinder 310 is divided into a plurality of zones in the axial direction (e.g., X-axis direction) of 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 in each of the plurality of zones, and control device 700 controls first heater 313 so that the temperature detected by first temperature detector 314 becomes the set temperature.

[0060] 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.

[0061] The screw 330 is disposed within the cylinder 310 so as to be rotatable and movable forward and backward. When the screw 330 is rotated, the molding material is fed forward along the spiral groove of the screw 330. As the molding material is fed forward, it is gradually melted by the heat from the cylinder 310. As the liquid molding material is fed forward of the screw 330 and accumulates in the front part of the cylinder 310, the screw 330 is moved backward. Thereafter, when the screw 330 is moved forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled into the mold device 800.

[0062] A backflow prevention ring 331 is attached to the front of the screw 330 so as to be movable back and forth as a backflow prevention valve for preventing the molding material from flowing back from the front to the rear of the screw 330 when the screw 330 is pushed forward.

[0063] 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 moves back relative to the screw 330 to a blocking position (see FIG. 2) where it blocks the flow path of the molding material. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

[0064] On the other hand, when the screw 330 is rotated, the backflow prevention ring 331 is pushed forward by the pressure of the molding material sent forward along the spiral groove of the screw 330, and moves forward relative to the screw 330 to the open position (see FIG. 1) where it opens the flow path of the molding material. This causes the molding material to be sent forward of the screw 330.

[0065] The backflow prevention ring 331 may be either a co-rotating type that rotates together with the screw 330 or a non-co-rotating type that does not rotate together with the screw 330.

[0066] The injection device 300 may have a drive source for moving the backflow prevention ring 331 back and forth relative to the screw 330 between the open position and the closed position.

[0067] 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.

[0068] The injection motor 350 advances and retreats the screw 330. A motion conversion mechanism that converts the rotational motion of the injection motor 350 into linear motion of the screw 330 is provided between the injection motor 350 and the screw 330. The motion conversion mechanism has, for example, a screw shaft and a screw nut that screws onto the screw shaft. A ball or roller may be provided between the screw shaft and the screw nut. The drive source that advances and retreats the screw 330 is not limited to the injection motor 350 and may be, for example, a hydraulic cylinder.

[0069] 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 on the load transmission path between the injection motor 350 and the screw 330, and detects the load acting on the load detector 360.

[0070] The load detector 360 sends a signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into pressure acting between the screw 330 and the molding material, and is used to control and monitor the pressure that the screw 330 receives from the molding material, the back pressure on the screw 330, the pressure that the screw 330 acts on the molding material, and the like.

[0071] The pressure detector that detects the pressure of the molding material is not limited to the load detector 360, and a general detector can be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle 320. The mold internal pressure sensor is installed inside the mold device 800.

[0072] The injection device 300 performs a metering process, a filling process, a pressure holding process, etc. under the control of the control device 700. The filling process and the pressure holding process may be collectively referred to as the injection process.

[0073] 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 sent forward along the spiral groove of the screw 330. As this happens, the molding material gradually melts. As the liquid molding material is sent forward to the screw 330 and accumulates at the front of the cylinder 310, the screw 330 is moved backward. The rotational speed of the screw 330 is detected, for example, using a metering motor encoder 341. The metering motor encoder 341 detects the rotation of the metering motor 340 and sends a signal indicating the detection result to the control device 700. Note that the screw rotational speed detector that detects the rotational speed of the screw 330 is not limited to the metering motor encoder 341, and a general one can be used.

[0074] In the metering process, in order to restrict abrupt 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 using, for example, a 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.

[0075] The position and rotational speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, a metering start position, a rotational speed switching position, and a metering completion position are set. These positions are arranged in this order from the front to the rear, and represent the start and end points of the section for which the rotational speed is set. The rotational speed is set for each section. There may be one or more rotational speed switching positions. The rotational speed switching position does not have to be set. In addition, a back pressure is set for each section.

[0076] 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, an 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 a set position, a switch from the filling process to a pressure holding process (so-called V / P switch) is performed. The position at which the V / P switch is performed is also called the V / P switch position. The set moving speed of the screw 330 may be changed depending on the position of the screw 330, time, etc.

[0077] The position and movement speed of the screw 330 in the filling process are set together as a series of setting conditions. For example, a filling start position (also called an "injection start position"), a movement speed switching position, and a V / P switching position are set. These positions are arranged in this order from rear to front, and represent the start and end points of the section for which the movement speed is set. The movement speed is set for each section. There may be one or more movement speed switching positions. The movement speed switching position does not have to be set.

[0078] An upper limit value for the pressure of the screw 330 is set for each section in which the movement speed of the screw 330 is set. The pressure of the screw 330 is detected by a load detector 360. When the pressure of the screw 330 is equal to or lower than the set pressure, the screw 330 is advanced at the set movement speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is advanced at a movement speed slower than the set movement speed so that the pressure of the screw 330 is equal to or lower than the set pressure, in order to protect the mold.

[0079] It should be noted that, after the position of the screw 330 reaches the V / P switching position during the filling process, the screw 330 may be temporarily stopped at the V / P switching position, and then V / P switching may be performed. Immediately before V / P switching, instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed. Furthermore, the screw position detector that detects the position of the screw 330 and the screw movement speed detector that detects the movement speed of the screw 330 are not limited to the injection motor encoder 351, and general detectors may be used.

[0080] In the dwelling step, the injection motor 350 is driven to push the screw 330 forward, maintaining the pressure of the molding material at the front end of the screw 330 (hereinafter also referred to as "holding pressure") at a set pressure, and pushing the molding material remaining in the cylinder 310 toward the mold device 800. This can replenish the molding material that is insufficient due to cooling contraction within the mold device 800. The holding pressure is detected, for example, using a load detector 360. The set value of the holding pressure may be changed depending on the elapsed time from the start of the dwelling step, etc. Multiple holding pressures and holding times for maintaining the holding pressure in the dwelling step may be set, or they may be set together as a series of setting conditions.

[0081] In the dwelling step, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and when the dwelling step is completed, the entrance to the cavity space 801 is blocked by the solidified molding material. This state is called a gate seal, and prevents the molding material from flowing back from the cavity space 801. After the dwelling step, the cooling step begins. In the cooling step, the molding material in the cavity space 801 is solidified. A metering step may be performed during the cooling step in order to shorten the molding cycle time.

[0082] The injection device 300 of this embodiment is of an in-line screw type, but may also be of a pre-plasticization type. A pre-plasticization type injection device supplies molding material molten in a plasticization cylinder to an injection cylinder, and injects the molding material from the injection cylinder into a mold device. A screw is disposed in the plasticization cylinder so that it can rotate freely but cannot move back and forth, or the screw is disposed so that it can rotate freely and move back and forth. Meanwhile, a plunger is disposed in the injection cylinder so that it can move back and forth.

[0083] Furthermore, although the injection unit 300 of this embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, it may be a vertical type in which the axial direction of the cylinder 310 is vertical. The mold clamping unit combined with the vertical injection unit 300 may be either a vertical type or a horizontal type. Similarly, the mold clamping unit combined with the horizontal injection unit 300 may be either a horizontal type or a vertical type.

[0084] (Mobile 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 (e.g., the negative X-axis direction) is defined as the front, and the moving direction of the screw 330 during metering (e.g., the positive X-axis direction) is defined as the rear.

[0085] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. The moving device 400 also presses the nozzle 320 against the mold device 800 to generate nozzle touch pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a drive source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

[0086] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectional pump, and by switching the rotation direction of the motor 420, it draws in hydraulic fluid (e.g., oil) from one of the first port 411 and the second port 412 and discharges it from the other, thereby generating hydraulic pressure. Note that the hydraulic pump 410 can also draw in hydraulic fluid from a tank and discharge it from either the first port 411 or the second port 412.

[0087] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 in a rotational direction and with a rotational torque according to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servo motor.

[0088] The hydraulic cylinder 430 has a cylinder body 431, a piston 432, and a piston rod 433. The cylinder body 431 is fixed to the injection device 300. The piston 432 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.

[0089] A front chamber 435 of the hydraulic cylinder 430 is connected to a first port 411 of the hydraulic pump 410 via a 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, thereby pushing the injection unit 300 forward. The injection unit 300 is moved forward, and the nozzle 320 is pressed against the fixed mold 810. The front chamber 435 functions as a pressure chamber that generates nozzle touch pressure of the nozzle 320 by the pressure of the hydraulic fluid supplied from the hydraulic pump 410.

[0090] Meanwhile, 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 via the second flow path 402, thereby pushing the injection unit 300 backward. The injection unit 300 is moved backward, and the nozzle 320 is separated from the fixed mold 810.

[0091] In this embodiment, the moving device 400 includes the hydraulic cylinder 430, but the present invention is not limited to this. For example, instead of the hydraulic cylinder 430, an electric motor and a motion conversion mechanism that converts the rotational motion of the electric motor into the linear motion of the injection device 300 may be used.

[0092] (Control device) The control device 700 is configured, for example, by 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 Figures 1 and 2. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. The control device 700 also receives signals from the outside via the input interface 703 and transmits signals to the outside via the output interface 704.

[0093] The control device 700 includes electronic circuits such as a CPU, an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), and performs the various control operations described in this specification by executing instruction codes stored in a memory or by being a circuit designed for a specific application.

[0094] The control device 700 repeatedly manufactures molded products by repeating processes such as a metering process, mold closing process, pressure increase process, mold clamping process, filling process, pressure dwell process, cooling process, pressure release process, mold opening process, and ejection process. A series of operations required to obtain a molded product, for example, the operations from the start of a metering process to the start of the next metering process, is also called a "shot" or a "molding cycle." The time required for one shot is also called the "molding cycle time" or "cycle time."

[0095] One molding cycle includes, for example, a metering process, a mold closing process, a pressurization process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a depressurization process, a mold opening process, and an ejection process, in this order. The order here refers to the order in which each process starts. 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 depressurization process coincides with the start of the mold opening process.

[0096] It should be noted that, in order to shorten the molding cycle time, multiple 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 at the beginning of the molding cycle. The filling process may be started during the mold closing process. The ejection process may be started during the mold opening process. If an on-off valve for opening and closing the flow path of the nozzle 320 is provided, the mold opening process may be started during the metering process. This is because, even if the mold opening process is started during the metering process, the molding material will not leak from the nozzle 320 as long as the on-off valve closes the flow path of the nozzle 320.

[0097] Note that one molding cycle may include steps other than the metering step, mold closing step, pressure increase step, mold clamping step, filling step, pressure holding step, cooling step, pressure release step, mold opening step, and ejection step.

[0098] For example, after the dwelling step is completed and before the metering step begins, a pre-metering suck-back step may be performed in which the screw 330 is retracted to a preset metering start position. This can reduce the pressure of the molding material accumulated in front of the screw 330 before the metering step begins, and prevent the screw 330 from retracting suddenly at the start of the metering step.

[0099] Furthermore, after the metering step is completed and before the filling step begins, a post-metering suck-back step may be performed in which the screw 330 is retracted to a preset filling start position (also referred to as the "injection start position"). This can reduce the pressure of the molding material accumulated in front of the screw 330 before the filling step begins, and can prevent the molding material from leaking from the nozzle 320 before the filling step begins.

[0100] The control device 700 is connected to an operation device 750 that accepts input operations by a user and a display device 760 that displays a screen. The operation device 750 and the display device 760 may be integrated, for example, by using a touch panel 770. The touch panel 770 serving as the display device 760 displays a screen under the control of the control device 700. The screen of the touch panel 770 may display information such as settings of the injection molding machine 10 and the current status of the injection molding machine 10. The screen of the touch panel 770 may also display operation units such as buttons and input fields that accept input operations by the user. The touch panel 770 serving as the operation device 750 detects input operations on the screen by the user and outputs signals corresponding to the input operations to the control device 700. This allows, for example, a user to operate the operation units provided on the screen while checking information displayed on the screen to perform settings of the injection molding machine 10 (including input of setting values). The user can also operate the operation units provided on the screen to cause the injection molding machine 10 to perform operations corresponding to the operation units. The operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the clamping device 100, the ejector device 200, the injection device 300, the moving device 400, etc. The operation of the injection molding machine 10 may also be the switching of a screen displayed on the touch panel 770 serving as the display device 760, etc.

[0101] Although the operation device 750 and the display device 760 of this embodiment have been described as being integrated as the touch panel 770, they may be provided independently. Also, a plurality of operation devices 750 may be provided. The operation device 750 and the display device 760 are disposed on the operation side (negative Y-axis direction) of the mold clamping unit 100 (more specifically, the fixed platen 110).

[0102] (Details of the injection unit) Next, the injection device 300 will be described in detail with reference to Fig. 3. The injection device 300 has, for example, a cylinder 310 that heats the molding material and a screw 330 provided inside the cylinder 310. The injection device 300 feeds the molding material from the upstream side to the downstream side (from right to left in Fig. 3) along a spiral groove formed in the screw 330 by rotating the screw 330. Hereinafter, the upstream side may be referred to as the rear side, and the downstream side may be referred to as the front side.

[0103] The cylinder 310 is divided into a plurality of (for example, five) zones Z0 to Z4 in the axial direction (for example, the X-axis direction) of the cylinder 310. A cooler 312 is provided in the most upstream zone Z0, and a first heater 313 and a first temperature detector 314 are provided in each of the remaining zones Z1 to Z4. A set temperature is set in each of the plurality of zones Z0 to Z4. The number of zones is not limited to five.

[0104] The control device 700 performs feedback control of the temperature of the coolant supplied from the coolant supplier 315 to the cooler 312 so that the actual temperature of zone Z0 becomes the set temperature. The cooler 312 suppresses a phenomenon called bridging by cooling the supply port 311 of the molding material. Bridging is a phenomenon in which resin pellets, which are the molding material, melt and clog. The cooler 312 is, for example, a water-cooled cylinder. The cooler 312 or the coolant supplier 315 may have a temperature detector.

[0105] The control device 700 detects the actual temperatures of each of the multiple zones Z1 to Z4 using the first temperature detector 314, and individually feedback controls the output of the first heater 313 for each of the zones Z1 to Z4 so that the actual temperatures detected by the first temperature detector 314 become the set temperatures. The multiple first heaters 313 may have the same configuration or different configurations. The first heaters 313 are, for example, band heaters.

[0106] The output of the first heater 313 is expressed, for example, as the percentage (%) of power-on time per unit time. The larger the percentage of power-on time, the higher the output of the first heater 313. Although not shown, when multiple first heaters 313 are provided in one zone, the percentage of power-on time of the multiple first heaters 313 is controlled to be the same. Furthermore, although not shown, multiple first temperature detectors 314 may be provided in one zone. The number of zones, the number of first heaters 313, and the number of first temperature detectors 314 do not have to match.

[0107] A nozzle 320 is attached to the front end of the cylinder 310. The nozzle 320 is pressed against a mold device 800 (see FIGS. 1 and 2) and injects a pre-melted molding material into 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 second heater 323 and the second temperature detector 324 are provided in zone Z5. The nozzle 320 and the second heater 323 constitute a nozzle assembly 303. The nozzle assembly 303 may include the second temperature detector 324.

[0108] The control device 700 detects the actual temperature of zone Z5 using the second temperature detector 324, and feedback controls the output of the second heater 323 so that the actual temperature detected by the second temperature detector 324 becomes the set temperature. The second heater 323 is, for example, a coil heater or a band heater. The output of the second heater 323 is expressed, for example, as a percentage (%) of power-on time per unit time.

[0109] Note that the nozzle 320 may also be divided into multiple zones in the X-axis direction, similar to the cylinder 310. A second heater 323 and a second temperature detector 324 are provided in each of the multiple zones. In this case, the control device 700 performs feedback control of the output of the second heater 323 for each zone individually. The multiple second heaters 323 may have the same configuration or different configurations.

[0110] The screw 330 is disposed within the cylinder 310 so as to be rotatable and movable forward and backward. When the metering motor 340 rotates the screw 330, the molding material is fed forward along the spiral groove of the screw 330. As the molding material is fed forward, it is gradually melted by the heat from the cylinder 310.

[0111] As the liquid molding material is sent forward of the screw 330 and accumulates in the front part of the cylinder 310, the screw 330 is moved backward. When the injection motor 350 then moves the screw 330 forward, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and fills the mold device 800. The screw 330 pushes the molding material forward.

[0112] The nozzle 320 has a flow path 321 formed therein through which the molding material flows from rear to front. The flow path 321 has a pocket portion A0 at its rear end. The front end of the screw 330 is inserted into the pocket portion A0. The hole diameter of the pocket portion A0 narrows toward the front. The hole diameter at the front end of the pocket portion A0 is smaller than the outer diameter of the screw 330. It is physically impossible for the screw 330 to advance forward beyond the pocket portion A0.

[0113] The injection molding machine 10 of this embodiment and the method for manufacturing a molded product will be described in more detail below with reference to FIGS.

[0114] Fig. 4 is a time chart showing the steps included in the manufacturing method of a molded product of this embodiment. Fig. 5 is a flow diagram explaining the first and second cooling steps of the nozzle 320. Fig. 6 is a cross-sectional view showing the state of the nozzle 320 before mold opening begins. Fig. 7 is a graph showing the refrigerant flow rates Q1 and Q2 in the first and second cooling steps, with the horizontal axis representing time T and the vertical axis representing the refrigerant flow rate Q. Fig. 8 is a cross-sectional view showing the state of the nozzle 320 after mold opening begins.

[0115] 6, the nozzle assembly 303 of the injection molding machine 10 of this embodiment is provided with a cooling unit 305 that cools the tip of the nozzle 320. The cooling unit 305 includes, for example, a refrigerant supplier 305A and a refrigerant flow path 305B.

[0116] Coolant supplier 305A includes, for example, a pump, a compressor, etc., and is a device that supplies a coolant for cooling nozzle 320. The coolant for cooling nozzle 320 is not particularly limited, and may be, for example, a gas such as air or an inert gas, or a liquid such as water or a coolant. Coolant supplier 305A is controlled by control device 700 to supply a predetermined flow rate of coolant to coolant flow path 305B.

[0117] Refrigerant flow path 305B is a flow path provided in nozzle 320 to circulate the refrigerant supplied from refrigerant supplier 305A. Refrigerant flow path 305B includes, for example, a pipe in contact with the outer surface of nozzle 320, or a through-hole formed in nozzle 320. In the example shown in Fig. 6, refrigerant flow path 305B is a pipe with a rectangular cross section that is in contact with a tapered surface provided at the tip of nozzle 320, and is provided so as to surround the tip of nozzle 320. The shape and arrangement of refrigerant flow path 305B are not particularly limited.

[0118] Coolant flow path 305B may be, for example, a pipe having a plurality of holes wound around the tip of nozzle 320. In this case, by circulating a gas such as air as a coolant through coolant flow path 305B, the coolant can be ejected from the plurality of holes to selectively cool the tip of nozzle 320.

[0119] The injection molding machine 10 of this embodiment is mainly characterized by the following configuration: The control device 700 executes a first cooling operation in which the cooling unit 305 cools the nozzle 320 after the clamping unit 100 starts clamping and before the mold opening starts, and a second cooling operation in which the cooling unit 305 cools the nozzle 320 after the mold opening starts and before the mold opening is completed.

[0120] In other words, the manufacturing method of a molded product of this embodiment is mainly characterized by having a first cooling step and a second cooling step. The first cooling step is a step of cooling the nozzle 320 that injected the molding material M in the filling step after the start of the mold clamping step and before the start of the mold opening step. The second cooling step is a step of cooling the nozzle 320 after the start of the mold opening step and before the completion of the mold opening step.

[0121] The timing for starting the first cooling step may be any time after the start of the mold clamping step, but is preferably after the start of the filling step, more preferably after the completion of the filling step, and even more preferably after the completion of the pressure holding step. It is preferable to cool the nozzle 320 after completing the injection of the molding material M. In addition, the timing for starting the first cooling step may be any time before the start of the mold opening step, but is preferably before the start of the pressure release step.

[0122] Specifically, the method for manufacturing a molded product of this embodiment includes, for example, as shown in Figure 4, the aforementioned single molding cycle, which includes a mold closing process, a pressure increase process, a mold clamping process, a pressure release process, a mold opening process, and an ejection process, in this order. The mold clamping process also includes, in this order, a filling process, a pressure dwell process, and a cooling process. The cooling process also includes a measuring process. The control device 700 starts the processing flow shown in Figure 5, for example, after the mold clamping process has started and before the mold opening process has started.

[0123] When the control device 700 starts the process flow shown in FIG. 5, it waits for a cooling trigger that triggers the cooling unit 305 to start cooling the nozzle 320 (process P01), and determines whether or not the cooling trigger has been detected (process P02).

[0124] The cooling trigger can be the start or end of any process that is performed after the start of the mold clamping process and before the start of the mold opening process, such as the completion of the pressure holding process or the completion of the cooling process. The cooling trigger may also be set according to an advance time that is a predetermined time before the completion of depressurization or the start of mold opening, for example.

[0125] For example, when the control device 700 determines that a cooling trigger has not been detected in process P02 (NO), it repeatedly executes processes P01 and P02, and when it determines that a cooling trigger has been detected in process P02 (YES), it starts the delay timer. The delay timer is started, for example, when the cooling trigger is detected, and is set to complete before the mold opening process is started.

[0126] Thereafter, the control device 700 executes process P03 to determine whether the delay timer has completed, and if it determines that the delay timer has not completed (NO), it repeats process P03, and if it determines that the delay timer has completed (YES), it starts the first cooling (process P04).

[0127] In this first cooling, the control device 700 cools the nozzle 320 using the cooling unit 305 shown in Fig. 6. More specifically, the control device 700 controls the refrigerant supply device 305A of the cooling unit 305 to start supplying the refrigerant at a predetermined flow rate Q1 from the refrigerant supply device 305A to the refrigerant flow path 305B of the cooling unit 305. As a result, for example, as shown in Fig. 7, before time T2 corresponding to the timing when mold opening starts, the refrigerant flows through the refrigerant flow path 305B at the predetermined flow rate Q1, and the tip of the nozzle 320 is cooled.

[0128] Thereafter, the control device 700 continues the first cooling of the nozzle 320 by the cooling unit 305, and determines whether the lower limit temperature of the nozzle 320 has been detected (process P05). If it determines that the lower limit temperature has not been detected (NO), it determines whether the cooling timer has completed (process P06). The temperature of the nozzle 320 is detected, for example, by the second temperature detector 324 shown in FIG. 3 or another temperature detector provided on the nozzle 320, and is input to the control device 700.

[0129] The lower limit temperature of the nozzle 320 in the first cooling step P05 is a temperature threshold of the nozzle 320, and is set to, for example, a temperature lower than the allowable lower limit temperature of the nozzle 320. In other words, the lower limit temperature of the nozzle 320 in step P05 is a temperature at which molding defects may occur in the molded product, such as a temperature at which the molten molding material at the tip of the nozzle 320 may solidify and cause a cold slug that clogs the nozzle 320. More specifically, the lower limit temperature of the nozzle 320 in step P05 is a temperature that is lower than the allowable lower limit temperature of the nozzle 320 and is within 10°C of the allowable lower limit temperature of the nozzle 320, for example.

[0130] The cooling timer for the first cooling is started, for example, simultaneously with the start of the first cooling (process P04), and is set to a predetermined time that completes before time T2, which is the timing when mold opening starts, as shown in Fig. 7. In the example shown in Fig. 7, the cooling timer for the first cooling is started before time T1, which is the timing when depressurization starts, and completes after time T1 has elapsed and before time T2, which is the timing when mold opening starts. The control device 700 can set the duration of the first cooling of the nozzle 320, for example, by setting the cooling timer.

[0131] If the control device 700 determines in the above-mentioned process P06 that the cooling timer has not completed (NO), it repeats the above-mentioned processes P05 and P06. Also, if the control device 700 determines in the above-mentioned process P05 that the lower limit temperature of the nozzle 320 has been detected (YES), it interrupts the first cooling of the nozzle 320 that started in the above-mentioned process P04, and ends the process flow shown in FIG.

[0132] In this case, the control device 700 may, for example, log the fact that the lower limit temperature of the first cooling of the nozzle 320 has been detected in this molding cycle, and terminate the processing flow shown in Fig. 5. This is to record the possibility that a molding defect has occurred in the molded product produced in this molding cycle. Thereafter, the control device 700 may continue the molding cycle by the injection molding machine 10, or may interrupt the molding cycle by the injection molding machine 10.

[0133] On the other hand, if the control device 700 repeatedly determines that the lower limit temperature of the nozzle 320 has not been detected (NO) in the aforementioned process P05, and determines that the cooling timer has completed (YES) in the aforementioned process P06, it ends the first cooling (process P07).

[0134] 7, the first cooling, in which the refrigerant at the flow rate Q1 is supplied to the refrigerant flow path 305B, is started before time T1, which is the timing when depressurization starts. More specifically, the first cooling of the nozzle 320 is started, for example, before time T1, which is the timing when depressurization starts, and is finished before time T2, which is the timing when mold opening starts. The timing when the first cooling starts may be close to time T1, which is the timing when depressurization starts.

[0135] 7, time T2, which is the timing when mold opening begins, is also the timing when depressurization is completed. That is, in the example shown in FIG. 7, the start of the mold opening process and the completion of the depressurization process coincide. Therefore, in a period S1 before time T2, the fixed mold 810 and the movable mold 820 are in close contact with each other, and in a period S2 after time T2, the fixed mold 810 and the movable mold 820 are separated from each other. Note that the completion of the depressurization process and the start of the mold opening process do not necessarily have to coincide, and there may be a predetermined delay time between the completion of the depressurization process and the start of the mold opening process.

[0136] Thereafter, the control device 700 starts waiting (process P08), for example, as shown in Fig. 5. In process P08, the control device 700 reduces the flow rate of the coolant supplied from the coolant supplier 305A to the coolant flow path 305B between the first cooling and the second cooling of the nozzle 320 to a value lower than the flow rates of the coolant in the first cooling and the second cooling. Specifically, in process P08, the control device 700 supplies the coolant from the coolant supplier 305A to the coolant flow path 305B at a flow rate Qs that is lower than the flow rate Q1 of the coolant in the first cooling and the flow rate Q2 of the coolant in the second cooling, for example, as shown in Fig. 7.

[0137] The flow rate Qs of the coolant supplied from the coolant supplier 305A to the coolant flow path 305B while the control device 700 is on standby may be zero. That is, the control device 700 may stop the supply of the coolant from the coolant supplier 305A to the coolant flow path 305B, for example, while on standby between the first cooling and the second cooling of the nozzle 320.

[0138] The control device 700 also starts a standby timer simultaneously with the start of the above-described process P08, and then executes process P09 to determine whether the standby timer has completed, repeating process P09 until it determines in process P09 that the standby timer has completed (YES). For example, as shown in FIG. 7, the standby timer is set to start before time T2, which is the timing at which mold opening starts, and to continue beyond time T2. For example, the standby timer is set to end after time T2 has elapsed but before time T3, which is the timing at which mold opening is completed. The control device 700 can, for example, set the standby timer to set the duration of the standby between the first cooling and the second cooling of the nozzle 320.

[0139] When the control device 700 determines in the above-mentioned process P09 that the standby timer has expired (YES), it ends the standby (process P10) and starts the second cooling of the nozzle 320 (process P11).

[0140] In this second cooling, the control device 700 cools the nozzle 320 using the cooling unit 305 shown in Fig. 8. More specifically, the control device 700 controls the refrigerant supply device 305A of the cooling unit 305 to start supplying the refrigerant at a predetermined flow rate Q2 from the refrigerant supply device 305A to the refrigerant flow path 305B of the cooling unit 305. As a result, for example, as shown in Fig. 7, after time T2 corresponding to the timing when mold opening starts, the refrigerant at the predetermined flow rate Q2 flows through the refrigerant flow path 305B, and the tip of the nozzle 320 is cooled.

[0141] 7, the control device 700 reduces the flow rate Q2 of the coolant during the second cooling of the nozzle 320 to be less than the flow rate Q1 of the coolant during the first cooling of the nozzle 320. Furthermore, the control device 700 reduces the supply time of the coolant during the second cooling of the nozzle 320 to be less than the supply time of the coolant during the first cooling of the nozzle 320 described above.

[0142] Thereafter, the control device 700 continues the second cooling of the nozzle 320 by the cooling unit 305, and determines whether the lower limit temperature of the nozzle 320 has been detected (process P12), and if it determines that the lower limit temperature has not been detected (NO), it determines whether the cooling timer has completed (process P13).

[0143] The lower limit temperature of the nozzle 320 in the second cooling process P12 is a temperature threshold of the nozzle 320 and is set, for example, to a temperature lower than the lower limit temperature of the nozzle 320 in the first cooling process P05 described above. The lower limit temperature of the nozzle 320 in this process P12 is, for example, a temperature lower than the upper limit temperature at which the molding material MA solidified in the sprue space 802 of the fixed mold 810 shown in FIG. 8 can be cut while suppressing stringing between the molding material MA and the molten molding material M remaining at the tip of the nozzle 320. That is, the control device 700 of this embodiment can separately set the lower limit temperature of the nozzle 320 in the first cooling process and the lower limit temperature of the nozzle 320 in the second cooling process.

[0144] The cooling timer for the second cooling is set to a predetermined time that starts, for example, at the same time as the start of the second cooling (process P11) and completes before time T3, which is the timing when mold opening is completed. In the example shown in Fig. 7, the cooling timer for the second cooling is set to start after time T2, which is the timing when mold opening starts, and completes before time T3, which is the timing when mold opening is completed. The control device 700 can set the duration of the second cooling of the nozzle 320, for example, by setting the cooling timer.

[0145] If the control device 700 determines in the above-mentioned process P13 that the cooling timer has not completed (NO), it repeats the above-mentioned processes P12 and P13. Furthermore, if the control device 700 determines in the above-mentioned process P12 that the lower limit temperature of the nozzle 320 has been detected (YES), it interrupts the second cooling of the nozzle 320 that started in the above-mentioned process P11, and ends the process flow shown in FIG.

[0146] In this case, the control device 700 may, for example, log the fact that the lower limit temperature of the second cooling of the nozzle 320 has been detected in this molding cycle, and terminate the processing flow shown in Fig. 5. This is to record the possibility that a molding defect has occurred in the molded product produced in this molding cycle or the next molding cycle. Thereafter, the control device 700 may continue the molding cycle by the injection molding machine 10, or may interrupt the molding cycle by the injection molding machine 10.

[0147] On the other hand, if the control device 700 repeatedly determines in the above-mentioned process P12 that the lower limit temperature of the second cooling of the nozzle 320 has not been detected (NO), and determines in the above-mentioned process P13 that the cooling timer for the second cooling has completed (YES), it ends the second cooling (process P14). This stops the supply of refrigerant from the refrigerant supplier 305A to the refrigerant flow path 305B. Thereafter, the control device 700 continues the molding cycle by the injection molding machine 10.

[0148] As described above, injection molding machine 10 of this embodiment includes mold clamping unit 100, which performs mold closing, pressurization, mold clamping, depressurization, and mold opening of mold apparatus 800; injection unit 300, which injects molding material into mold apparatus 800; and control device 700, which controls mold clamping unit 100 and injection unit 300. Injection unit 300 includes nozzle 320, which defines flow path 321 therein through which molding material flows, and cooling unit 305, which cools nozzle 320. Control device 700 performs first cooling (processes P04 to P07), in which cooling unit 305 cools nozzle 320 after mold clamping begins and before mold opening begins, and second cooling (processes P11 to P14), in which cooling unit 305 cools nozzle 320 after mold opening begins and before mold opening is completed. Furthermore, the control device 700 stops the supply of the refrigerant to the cooling unit 305 or reduces the flow rate between the first cooling and the second cooling (processes P08 to P10).

[0149] With this configuration, the injection molding machine 10 of this embodiment can achieve high transfer molding and suppress stringing. Specifically, while increasing the temperature of the molding material to achieve high transfer molding of the molded product, the control device 700 executes the first and second cooling of the nozzle 320, thereby suppressing stringing between the molded product and the molten molding material in the nozzle 320. More specifically, by executing the first cooling of the nozzle 320 before the start of mold opening, the nozzle 320 can be cooled to a level that prevents cold slugs from forming at the tip of the nozzle 320. Furthermore, by executing the second cooling of the nozzle 320 after the start of mold opening, the temperature of the nozzle 320, which was lowered by the first cooling, is further lowered. As a result, as shown in FIG. 8 , the elongational viscosity is increased at the planned cutting location near the boundary between the molten molding material M in the nozzle 320 and the solidified molding material MA in the mold device 800, and the molding material M is cut at the planned cutting location. The reason for executing the second cooling after the start of mold opening is to efficiently increase the elongational viscosity at the planned cutting location between the molten molding material M and the solidified molding material MA. As a result, even if the temperature of the molding material is increased, the molding material can be cut while suppressing stringing of the molding material. Furthermore, by stopping the supply of refrigerant to the cooling section 305 or reducing the flow rate of the refrigerant between the first and second cooling stages, it is possible to prevent the nozzle 320 from being excessively cooled. Therefore, the injection molding machine 10 of this embodiment can achieve high transfer molding and suppress stringing. Furthermore, by shortening the refrigerant supply time during the second cooling stage after mold opening begins, it is possible to shorten the time required for one molding cycle and improve the productivity of molded products.

[0150] Furthermore, in the injection molding machine 10 of this embodiment, the control device 700 may stop the supply of the refrigerant to the cooling section 305 or reduce the flow rate when mold opening begins (processes P08 to P10).

[0151] This configuration makes it possible to prevent the temperature of the nozzle 320 from dropping more than necessary between the first and second cooling of the nozzle 320 at the start of mold opening. Furthermore, by continuing to supply the coolant from the coolant supplier 305A to the coolant flow path 305B at a predetermined flow rate Qs while the control device 700 is on standby between the first and second cooling, it is possible to prevent the temperature of the nozzle 320, which is heated to a temperature within a predetermined temperature range, from overshooting.

[0152] Furthermore, in the injection molding machine 10 of this embodiment, the injection device 300 includes a second temperature detector 324 that is a temperature detector that detects the temperature of the nozzle 320. The control device 700 interrupts the first cooling and the second cooling when the temperature of the nozzle 320 detected by the second temperature detector 324 falls below a threshold value (processes P05 and P12).

[0153] With this configuration, if the temperature of the nozzle 320 drops too low during the first or second cooling, potentially resulting in molding defects in the molded product, the first and second cooling processes can be interrupted to prevent further defects. The lower limit temperature, which is the temperature threshold for the nozzle 320 during the first and second cooling processes, is different from the target temperature used to control the temperature of the nozzle 320; it is merely a temperature threshold for the nozzle 320 for interrupting the first and second cooling processes. In other words, in this embodiment, feedback control based on a target temperature for the nozzle 320 is not performed. This is because the second temperature detector 324, which measures the temperature of the nozzle 320, has a large time constant with respect to changes in the temperature of the nozzle 320, making it difficult to control the temperature of the nozzle 320 to a temperature that does not generate cold slugs using feedback control based on a target temperature for the nozzle 320.

[0154] Furthermore, in the injection molding machine 10 of this embodiment, the control device 700 can set the duration of the first cooling and the duration of the second cooling. With this configuration, it becomes possible to efficiently control the temperature of the nozzle 320 at the end of the first cooling and the temperature of the nozzle 320 at the end of the second cooling.

[0155] Furthermore, in the injection molding machine 10 of this embodiment, the control device 700 can set the duration of the first cooling, the duration of the standby period during which the supply of refrigerant is stopped or the flow rate is reduced, and the duration of the second cooling. With this configuration, it is possible to efficiently control the temperature of the nozzle 320 at the end of the first cooling, the temperature of the nozzle 320 at the start of the second cooling, and the temperature of the nozzle 320 at the end of the second cooling.

[0156] Furthermore, in the injection molding machine 10 of this embodiment, the control device 700 reduces the flow rate of the refrigerant in the second cooling step to be lower than the flow rate of the refrigerant in the first cooling step. This configuration prevents the temperature of the nozzle 320 from decreasing too much in the second cooling step. It also makes it possible to reduce the energy used to supply the refrigerant in the second cooling step.

[0157] Furthermore, in the injection molding machine 10 of this embodiment, the control device 700 reduces the refrigerant supply time in the second cooling step compared to the refrigerant supply time in the first cooling step. This configuration prevents the nozzle 320 from dropping too low in temperature during the second cooling step. Furthermore, the time required for the second cooling step can be shortened, allowing thread trimming of the molding material without stopping mold opening. This also reduces the energy used to supply the refrigerant during the second cooling step.

[0158] The method for manufacturing a molded product of this embodiment includes a metering step, a mold closing step, a pressurization step, a mold clamping step, a filling step, a pressure holding step, a cooling step, a depressurization step, a mold opening step, and an ejection step. The method for manufacturing a molded product of this embodiment also includes a first cooling step (steps P04 to P07) for cooling the nozzle 320 that injected the molding material in the filling step after the start of the mold clamping step and before the start of the mold opening step, a second cooling step (steps P11 to P14) for cooling the nozzle 320 after the start of the mold opening step and before the completion of the mold opening step, and a step (steps P08 to P10) for stopping or reducing the flow rate of the coolant supply to the cooling unit 305 that cools the nozzle 320 between the first and second cooling steps.

[0159] With this configuration, the manufacturing method for a molded product of this embodiment can achieve high transfer molding and suppress stringing. Specifically, by increasing the temperature of the molding material to achieve high transfer molding of the molded product, and by performing the first and second cooling steps of the nozzle 320, it is possible to suppress stringing between the molded product and the molten molding material in the nozzle 320. More specifically, by performing the first cooling step of the nozzle 320 before the start of the mold opening step, it is possible to cool the nozzle 320 to a level that does not cause cold slugs to form at the tip of the nozzle 320. Furthermore, by performing the second cooling step of the nozzle 320 after the start of the mold opening step, it is possible to further reduce the temperature of the nozzle 320, which was reduced in the first cooling step, and form a boundary between the molten molding material in the nozzle 320 and the solidified molding material in the mold device 800. As a result, even if the temperature of the molding material is increased, it is possible to cut the molding material while suppressing stringing of the molding material. Moreover, by stopping the supply of the coolant to the cooling unit 305 or reducing the flow rate of the coolant between the first cooling step and the second cooling step, it is possible to prevent the nozzle 320 from being excessively cooled. Therefore, according to the manufacturing method of the molded product of this embodiment, it is possible to achieve high transfer molding and suppress stringiness.

[0160] As described above, according to the present embodiment, it is possible to provide an injection molding machine and a method for manufacturing a molded product that can achieve high transfer molding and suppress stringing.

[0161] The preferred embodiments of the present disclosure have been described above. However, the invention according to the present disclosure is not limited to the above-described embodiments. Various modifications, substitutions, etc. may be applied to the above-described embodiments without departing from the scope of the invention according to the present disclosure. Furthermore, each of the features described with reference to the above-described embodiments may be combined as appropriate as long as there is no technical contradiction.

[0162] For example, the present disclosure can be applied not only to the nozzle of an injection molding machine, but also to parts through which molten molding material passes, such as valve gates and hot runners, i.e., parts where a boundary between the molten molding material and the solidified molding material is desired. Furthermore, the control device may temporarily suspend the mold opening operation after mold opening begins at a length at which stringing of the molding material is desired to be cut. Even when the control device temporarily suspends mold opening, the control device can shorten the time the mold opening is paused by performing first and second cooling of the nozzle. Furthermore, the control device may reduce the flow rate of the refrigerant supplied from the refrigerant supplier to the refrigerant flow path when it detects the lower limit temperature of the nozzle for the first and second cooling. [Explanation of symbols]

[0163] 100 Mold clamping device 300 Injection device 305 Cooling section 305A Refrigerant supply device 305B Refrigerant flow path 320 nozzle 321 Channel 324 Second temperature detector (temperature detector) 700 control device 800 mold equipment M Molding material P04 Treatment (1st cooling / 1st cooling process) P05 Treatment (1st cooling / 1st cooling process) P06 Processing (1st cooling / 1st cooling process) P07 Treatment (1st cooling / 1st cooling process) P08 Treatment (Process to stop the supply of refrigerant or reduce the flow rate) P09 Treatment (Process to stop the supply of refrigerant or reduce the flow rate) P10 Treatment (Process to stop the supply of refrigerant or reduce the flow rate) P11 Treatment (Second Cooling / Second Cooling Process) P12 Treatment (Second Cooling / Second Cooling Process) P13 Treatment (Second Cooling / Second Cooling Process) P14 Treatment (Second Cooling / Second Cooling Process) Q1 Flow rate Q2 Traffic Qs traffic

Claims

1. a mold clamping device that performs mold closing, pressurization, mold clamping, depressurization, and mold opening of the mold device; an injection device that injects a molding material into the mold device; a control device that controls the mold clamping device and the injection device, the injection device includes a nozzle that forms a flow path through which the molding material flows, and a cooling unit that cools the nozzle, The control device performs first cooling to cool the nozzle using the cooling unit after the start of mold clamping and before the start of mold opening, and second cooling to cool the nozzle using the cooling unit after the start of mold opening and before the completion of mold opening, and stops the supply of refrigerant to the cooling unit or reduces the flow rate between the first cooling and the second cooling.

2. the control device stops the supply of the coolant or reduces the flow rate when the mold opening starts.

2. The injection molding machine according to claim 1.

3. the injection device includes a temperature detector that detects a temperature of the nozzle; the control device interrupts the first cooling and the second cooling when the temperature of the nozzle detected by the temperature detector falls below a threshold value.

3. The injection molding machine according to claim 1 or 2.

4. The control device is capable of setting a duration of the first cooling period and a duration of the second cooling period.

3. The injection molding machine according to claim 1 or 2.

5. the control device is capable of setting a duration of the first cooling, a duration of stopping the supply of the refrigerant or reducing the flow rate of the refrigerant, and a duration of the second cooling.

3. The injection molding machine according to claim 2.

6. the control device reduces the flow rate of the refrigerant in the second cooling step to be lower than the flow rate of the refrigerant in the first cooling step.

3. The injection molding machine according to claim 2.

7. the control device reduces a supply time of the refrigerant in the second cooling period to be shorter than a supply time of the refrigerant in the first cooling period.

3. The injection molding machine according to claim 2.

8. A method for manufacturing a molded product, comprising a metering step, a mold closing step, a pressurizing step, a mold clamping step, a filling step, a pressure holding step, a cooling step, a depressurizing step, a mold opening step, and an ejection step, a first cooling step of cooling the nozzle that injected the molding material in the filling step after the start of the mold clamping step and before the start of the mold opening step; a second cooling step of cooling the nozzle after the mold opening step starts and before the mold opening step is completed; a step of stopping or reducing the flow rate of the coolant to a cooling unit that cools the nozzle between the first cooling step and the second cooling step. Manufacturing method of molded products.

Images