Injection molding machine

Abstract

The invention provides a technology capable of reducing deviation of metering time. An injection molding machine includes: a cylinder having a supply port for a molding material; a heater for heating the cylinder; the screw rod is arranged in the cylinder body; and a spiral groove which is formed on the outer periphery of the screw rod, and which conveys the molding material from the rear to the front along the groove by rotating the screw rod. The screw has a supply part and a compression part in this order from the supply port toward the front. (1) D1 / D0 is from 0.140 to 0.260 (inclusive), and (2) D1 / D2 is from 2.50 to 3.80 (inclusive). When the screw is located at the forward limit position, the rear end of the compression part and the rear end of the heater closest to the rear among the heaters closer to the front than the supply port are located at the same position or located at the front position. (3) V1 / V2 is 0.00 or more and less than 12.50.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2023-177211 filed on October 13, 2023. The entire contents of the Japanese Patent Application are incorporated herein by reference.

[0002] The present invention relates to an injection molding machine. Background Art

[0003] The injection molding machine includes a cylinder, a heater for heating the cylinder, a screw disposed inside the cylinder, and a spiral groove formed on the outer circumference of the screw. The injection molding machine performs a metering process and an injection process. In the metering process, the screw is rotated at a set speed to convey the molding material from the rear to the front along the spiral groove. The molding material gradually melts while moving from the rear to the front. As the liquid molding material is conveyed to the front of the screw and accumulated in the front of the cylinder, the screw retreats. In the metering process, a set back pressure can be applied to the screw in order to limit the rapid retreat of the screw. When the screw retreats to the metering completion position and a specified amount of molding material is accumulated in front of the screw, the metering process is completed.

[0004] In the injection process, the screw is moved forward at a set moving speed, and the liquid molding material accumulated in front of the screw is injected from the cylinder into the mold device. The injection molding machine fills the liquid molding material into the cavity space inside the mold device. By solidifying the filled molding material, a molded product can be obtained. The shape and size of the molded product are equal to the shape and size of the cavity space.

[0005] The screw described in Patent Document 1 has a compression section and a metering section from the rear end to the front end. The groove depth of the compression section changes smoothly. The groove depth of the metering section is constant. The ratio of the groove depth at the rear end of the compression section to the groove depth of the metering section is 1.4 to 2.0.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-131854

[0007] Hereinafter, the time of the metering process is referred to as metering time. The deviation of metering time indicates the deviation of at least one of the temperature, viscosity and density of the liquid molding material accumulated in front of the screw inside the cylinder. These deviations will lead to the quality deviation of the molded product.

[0008] The deviation of the metering time is significant when using a crystalline resin as a molding material. Crystalline resins are different from amorphous resins and have a melting point. The viscosity of crystalline resins changes sharply with the melting point as the boundary. Therefore, the deviation of the metering time of crystalline resins tends to become larger. Among crystalline resins, the viscosity of LCP resins (liquid crystal polymers) tends to become lower when the temperature reaches the melting point, and the deviation of the metering time tends to become larger. Summary of the invention

[0009] One aspect of the present invention provides a technology capable of reducing the variation in measurement time.

[0010] An injection molding machine according to one embodiment of the present invention comprises: a cylinder having a supply port for molding material; a heater for heating the cylinder; a screw disposed inside the cylinder; and a spiral groove formed on the outer periphery of the screw, wherein the injection molding machine transports the molding material from the rear to the front along the groove by rotating the screw. The screw comprises, in order from the supply port toward the front: a supply portion having a constant groove depth; and a compression portion, wherein the groove depth becomes shallower as it moves from the front end of the supply portion toward the front. If the diameter of the screw is set to D0, the depth of the groove at the rear end of the compression portion is set to D1, and the depth of the groove at the front end of the compression portion is set to D2, then (1) D1 / D0 is greater than 0.140 and less than 0.260, and (2) D1 / D2 is greater than 2.50 and less than 3.80. When the screw is at the forward limit position, the rear end of the compression section is at the same position as or in front of the rear end of the heater that is the rearmost heater among the heaters that are further forward than the supply port. If the volume of the groove from the rear end of the rearmost heater to the rear end of the compression section when the screw is at the forward limit position is set to V1, and the volume of the groove of the supply section at the rear end of the rearmost heater when the screw is at the forward limit position is set to V2, then (3) V1 / V2 is greater than 0.00 and less than 12.50.

[0011] Effects of the Invention

[0012] According to one aspect of the present invention, it is possible to reduce the variation in measurement time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram showing a state of the injection molding machine according to one embodiment when mold opening is completed.

[0014] Figure 2 It is a diagram showing a state of the injection molding machine according to one embodiment when the mold is clamped.

[0015] Figure 3 This is a diagram showing an example of a cylinder and a screw.

[0016] Figure 4 This is a diagram showing an example of a screw.

[0017] Figure 5 An example of melt film and backflow is shown.

[0018] Figure 6This is a table showing the screw structures and standard deviations of metering times according to Examples 1 to 3.

[0019] Figure 7 It is a box plot showing the standard deviation of the measurement time according to Examples 1 to 3.

[0020] In the figure: 10-injection molding machine, 310-cylinder, 313-first heater (heater), 330-screw, 334-groove, X1-supply section, X2-compression section. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each of the drawings, the same or corresponding structures are denoted by the same reference numerals, and description thereof may be omitted.

[0022] (Injection Molding Machine)

[0023] Figure 1 This is a diagram showing a state of the injection molding machine according to one embodiment when mold opening is completed. Figure 2 1 is a diagram showing a state of an injection molding machine involved in an embodiment when the mold is clamped. In this specification, the X-axis direction, the Y-axis direction and the Z-axis direction are directions perpendicular to each other. The X-axis direction and the Y-axis direction represent horizontal directions, and the Z-axis direction represents a vertical direction. When the clamping device 100 is horizontal, the X-axis direction is the mold opening and 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 opposite side of the operating side.

[0024] like Figure 1-2 As shown, the injection molding machine 10 includes: a mold clamping device 100 for opening and closing a mold device 800; an ejection device 200 for ejecting a molded product molded by the mold device 800; an injection device 300 for injecting a molding material into the mold device 800; a moving device 400 for moving the injection device 300 forward and backward relative to the mold device 800; a control device 700 for controlling each component of the injection molding machine 10; and a frame 900 for supporting each component of the injection molding machine 10. The frame 900 includes a mold clamping device frame 910 for supporting the mold clamping device 100 and an injection device frame 920 for supporting the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are respectively installed on the floor 2 via a leveling adjuster 930. The control device 700 is arranged in the internal space of the injection device frame 920. Hereinafter, each component of the injection molding machine 10 will be described.

[0025] (Mold clamping device)

[0026] In the description of the mold clamping device 100, the moving direction of the movable platen 120 when the mold is closed (for example, the positive direction of the X axis) is set to the front, and the moving direction of the movable platen 120 when the mold is opened (for example, the negative direction of the X axis) is set to the rear.

[0027] The mold clamping device 100 performs mold closing, pressure raising, mold clamping, pressure release, and mold opening of the mold device 800. The mold device 800 includes a fixed mold 810 and a movable mold 820.

[0028] The mold clamping device 100 is, for example, a horizontal type, and the mold opening and closing direction is the horizontal direction. The mold clamping device 100 includes a fixed platen 110 to which the fixed mold 810 is mounted, a movable platen 120 to which the movable mold 820 is mounted, and a moving mechanism 102 to move the movable platen 120 relative to the fixed platen 110 in the mold opening and closing direction.

[0029] The fixed platen 110 is fixed to the mold clamping device frame 910. The fixed mold 810 is mounted on the surface of the fixed platen 110 that faces the movable platen 120.

[0030] The movable platen 120 is arranged to be movable in the mold opening and closing direction relative to the mold clamping device frame 910. A guide 101 for guiding the movable platen 120 is laid on the mold clamping device frame 910. The movable mold 820 is mounted on the surface of the movable platen 120 facing the fixed platen 110.

[0031] The moving mechanism 102 closes, pressurizes, clamps, releases, and opens the mold of the mold device 800 by moving the movable platen 120 forward and backward relative to the fixed platen 110. The moving mechanism 102 includes: a toggle seat 130, which is arranged at a distance from the fixed platen 110; a connecting rod 140, which connects the fixed platen 110 and the toggle seat 130; a toggle mechanism 150, which moves the movable platen 120 relative to the toggle seat 130 in the mold opening and closing direction; a clamping motor 160, which operates the toggle mechanism 150; a motion conversion mechanism 170, which converts the rotational motion of the clamping motor 160 into a linear motion; and a mold thickness adjustment mechanism 180, which adjusts the distance between the fixed platen 110 and the toggle seat 130.

[0032] The toggle seat 130 is arranged at a distance from the fixed platen 110 and is placed on the mold clamping device frame 910 so as to be movable in the mold opening and closing direction. In addition, the toggle seat 130 can be arranged so as to be movable along a guide member laid on the mold clamping device frame 910. The guide member of the toggle seat 130 can be common to the guide member 101 of the movable platen 120.

[0033] In addition, in the present embodiment, the fixed pressure plate 110 is fixed to the mold clamping device frame 910, and the elbow seat 130 is arranged on the mold clamping device frame 910 so as to be freely movable in the mold opening and closing direction. However, the elbow seat 130 may also be fixed to the mold clamping device frame 910, and the fixed pressure plate 110 may be arranged on the mold clamping device frame 910 so as to be freely movable in the mold opening and closing direction.

[0034] The connecting rod 140 connects the fixed platen 110 and the toggle seat 130 at a distance L in the mold opening and closing direction. A plurality of connecting rods 140 (e.g., 4) may be used. The plurality of connecting rods 140 are arranged in parallel in the mold opening and closing direction and extend according to the mold clamping force. A connecting rod strain detector 141 for detecting the strain of the connecting rod 140 may be provided on at least one of the connecting rods 140. The connecting rod strain detector 141 sends a signal indicating its detection result to the control device 700. The detection result of the connecting rod strain detector 141 is used for detecting the mold clamping force, etc.

[0035] In addition, in the present embodiment, the tie rod strain detector 141 is used as the mold clamping force detector for detecting the mold clamping force, but the present invention is not limited to this. The mold clamping force detector is not limited to the strain type, and may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, etc., and its installation position is not limited to the tie rod 140.

[0036] The toggle mechanism 150 is arranged between the movable platen 120 and the toggle seat 130, and moves the movable platen 120 in the mold opening and closing direction relative to the toggle seat 130. The toggle mechanism 150 includes a crosshead 151 that moves in the mold opening and closing direction and a pair of link groups that are extended and retracted by the movement of the crosshead 151. The pair of link groups each includes a first link 152 and a second link 153 that are connected to each other by a pin or the like so as to be retractable. The first link 152 is swingably mounted on the movable platen 120 by a pin or the like. The second link 153 is swingably mounted on the toggle seat 130 by a pin or the like. The second link 153 is mounted on the crosshead 151 via a third link 154. When the crosshead 151 is moved forward and backward relative to the toggle seat 130, the first link 152 and the second link 153 are extended and retracted, and the movable platen 120 moves forward and backward relative to the toggle seat 130.

[0037] In addition, the structure of the toggle mechanism 150 is not limited to Figure 1 and Figure 2 For example, in Figure 1 and Figure 2 In the embodiment, the number of nodes of each link group is five, but may be four. One end of the third link 154 may be connected to the node between the first link 152 and the second link 153 .

[0038] The mold clamping motor 160 is mounted on the toggle base 130 and operates the toggle mechanism 150. The mold clamping motor 160 causes the cross head 151 to move forward and backward relative to the toggle base 130, thereby extending and retracting the first link 152 and the second link 153, and causing the movable platen 120 to move forward and backward relative to the toggle base 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.

[0039] The motion conversion mechanism 170 converts the rotational motion of the mold clamping motor 160 into the linear motion of the cross head 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

[0040] The mold clamping device 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure releasing process, a mold opening process, and the like under the control of the control device 700 .

[0041] In the mold closing process, the mold clamping motor 160 is driven to move the crosshead 151 to the mold closing completion position at a set moving speed, thereby moving the movable platen 120 forward and bringing the movable mold 820 into contact with the fixed mold 810. The position and moving speed of the crosshead 151 are detected using, for example, 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.

[0042] In addition, the crosshead position detector for detecting the position of the crosshead 151 and the crosshead moving speed detector for detecting the moving speed of the crosshead 151 are not limited to the mold clamping motor encoder 161, and a general detector can be used. In addition, the movable platen position detector for detecting the position of the movable platen 120 and the movable platen moving speed detector for detecting the moving speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and a general detector can be used.

[0043] In the pressure increasing step, the mold clamping motor 160 is further driven to move the cross head 151 further from the mold closing completion position to the mold clamping position, thereby generating a mold clamping force.

[0044] In the mold clamping process, the mold clamping motor 160 is driven to maintain the position of the cross head 151 at the mold clamping position. In the mold clamping process, the mold clamping force generated in the pressure increasing process is maintained. In the mold clamping process, a cavity space 801 is formed between the movable mold 820 and the fixed mold 810 (refer to Figure 2 ), the injection device 300 fills the liquid molding material into the cavity space 801. The filled molding material is solidified to obtain a molded product.

[0045] The number of cavity spaces 801 may be one or more. In the latter case, multiple molded products can be obtained at the same time. It is also possible to configure an insert in a part of the cavity space 801 and fill the molding material in another part of the cavity space 801. A molded product in which the insert and the molding material are integrated can be obtained.

[0046] In the depressurization process, the mold clamping motor 160 is driven to retract the crosshead 151 from the mold clamping position to the mold opening start position, so that the movable platen 120 is retracted to reduce the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

[0047] In the mold opening process, the mold clamping motor 160 is driven to move the crosshead 151 backward from the mold opening start position to the mold opening completion position at a set moving speed, so that the movable platen 120 is retreated and the movable mold 820 is separated from the fixed mold 810. Then, the ejector device 200 ejects the molded product from the movable mold 820.

[0048] The setting conditions in the mold closing process, the pressure increasing process and the mold clamping process are set together as a series of setting conditions. For example, the moving speed and position (including the mold closing start position, the moving speed switching position, the mold closing completion position and the mold clamping position) and the mold clamping force of the crosshead 151 in the mold closing process and the pressure increasing process are set together as a series of setting conditions. The mold closing start position, the moving speed switching position, the mold closing completion position and the mold clamping position are arranged in sequence from the back to the front, indicating the starting point and end point of the interval for setting the moving speed. Set the moving speed in each interval. The moving speed switching position can be one or more. The moving speed switching position can also be not set. Only one of the mold clamping position and the mold clamping force can be set.

[0049] The setting conditions in the pressure release process and the mold opening process are also set in the same way. For example, the moving speed and position (mold opening start position, moving speed switching position and mold opening completion position) of the crosshead 151 in the pressure release process and the mold opening process are set together as a series of setting conditions. The mold opening start position, the moving speed switching position and the mold opening completion position are arranged in sequence from the front to the back, indicating the starting point and end point of the interval for setting the moving speed. The moving speed is set in each interval. The moving speed switching position can be one or more. The moving speed switching position can also be not set. The mold opening start position and the mold closing completion position can be the same position. In addition, the mold opening completion position and the mold closing start position can be the same position.

[0050] Alternatively, 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 mold clamping force may be set instead of the position of the crosshead 151 (for example, the mold clamping position) and the position of the movable platen 120.

[0051] The toggle mechanism 150 amplifies the driving force of the mold clamping motor 160 and transmits it to the movable platen 120. This amplification ratio is also called a toggle ratio. The toggle ratio changes according to the angle θ (hereinafter also referred to as "link angle θ") formed by the first link 152 and the second link 153. The link angle θ is obtained according to the position of the crosshead 151. When the link angle θ is 180°, the toggle ratio is maximum.

[0052] When the thickness of the mold device 800 changes due to replacement of the mold device 800 or temperature change of the mold device 800, mold thickness adjustment is performed to obtain a predetermined mold clamping force when the mold is clamped. In the mold thickness adjustment, for example, the interval L between the fixed platen 110 and the toggle seat 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the mold contacting moment when the movable mold 820 contacts the fixed mold 810.

[0053] The mold clamping device 100 has a mold thickness adjustment mechanism 180. The mold thickness adjustment mechanism 180 adjusts the mold thickness by adjusting the interval L between the fixed platen 110 and the toggle seat 130. In addition, the mold thickness adjustment timing is, for example, performed during the period from the end of the molding cycle to 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 connecting rod 140, a screw nut 182 rotatably held in the toggle seat 130 and unable to move forward and backward, and a mold thickness adjustment motor 183 that rotates the screw nut 182 screwed to the screw shaft 181.

[0054] The lead screw shaft 181 and the lead screw nut 182 are provided on each connecting rod 140. The rotational driving force of the mold thickness adjustment motor 183 can be transmitted to the plurality of lead screw nuts 182 via the rotational driving force transmission unit 185. The plurality of lead screw nuts 182 can be rotated synchronously. In addition, by changing the transmission path of the rotational driving force transmission unit 185, the plurality of lead screw nuts 182 can also be rotated individually.

[0055] The rotational driving force transmission part 185 is composed of, for example, gears. In this case, a driven gear is formed on the outer periphery of each lead screw nut 182, a driving gear is mounted on the output shaft of the mold thickness adjustment motor 183, and an intermediate gear meshing with a plurality of driven gears and the driving gear is rotatably held at the center of the toggle seat 130. In addition, the rotational driving force transmission part 185 may be composed of a belt and a pulley instead of a gear.

[0056] The operation of the mold thickness adjustment mechanism 180 is controlled by the control device 700. The control device 700 drives the mold thickness adjustment motor 183 to rotate the lead screw nut 182. As a result, the position of the toggle seat 130 relative to the connecting rod 140 is adjusted, and the interval L between the fixed platen 110 and the toggle seat 130 is adjusted. In addition, a plurality of mold thickness adjustment mechanisms may be used in combination.

[0057] The interval L is detected using the mold thickness adjustment motor encoder 184. The mold thickness adjustment motor encoder 184 detects the rotation amount and rotation direction of the mold thickness adjustment motor 183, and sends a signal indicating the detection result to the control device 700. The detection result of the mold thickness adjustment motor encoder 184 is used to monitor and control the position of the toggle seat 130 and the interval L. In addition, the toggle seat position detector for detecting the position of the toggle seat 130 and the interval detector for detecting the interval L are not limited to the mold thickness adjustment motor encoder 184, and a general detector can be used.

[0058] The mold clamping device 100 may include a mold temperature regulator for regulating the temperature of the mold device 800. The mold device 800 has a flow path of a temperature regulating medium therein. The mold temperature regulator regulates the temperature of the mold device 800 by regulating the temperature of the temperature regulating medium supplied to the flow path of the mold device 800.

[0059] Furthermore, the mold clamping device 100 of the present embodiment is a horizontal type mold clamping device in which the mold opening and closing direction is the horizontal direction, but may be a vertical type mold clamping device in which the mold opening and closing direction is the vertical direction.

[0060] The mold clamping device 100 of this embodiment includes the mold clamping motor 160 as a driving source, but may include a hydraulic cylinder instead of the mold clamping motor 160. Furthermore, the mold clamping device 100 may include a linear motor for mold opening and closing and an electromagnet for mold clamping.

[0061] (Ejector device)

[0062] In the description of the ejection device 200, similar to the description of the mold clamping device 100, the moving direction of the movable platen 120 when the mold is closed (for example, the positive direction of the X-axis) is set to the front and the moving direction of the movable platen 120 when the mold is opened (for example, the negative direction of the X-axis) is set to the rear.

[0063] The ejector device 200 is mounted on the movable platen 120 and moves forward and backward together with the movable platen 120. The ejector device 200 includes an ejector rod 210 for ejecting a molded product from the mold device 800, and a drive mechanism 220 for moving the ejector rod 210 in the moving direction of the movable platen 120 (X-axis direction).

[0064] The ejector rod 210 is arranged to be able to move forward and backward in the through hole of the movable platen 120. The front end of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The front end of the ejector rod 210 may be connected to the ejector plate 826 or may not be connected thereto.

[0065] The driving 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 screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

[0066] The ejector device 200 performs an ejection process under the control of the control device 700. In the ejection process, the ejector rod 210 is moved forward from the standby position to the ejection position at a set moving speed, and the ejector plate 826 is moved forward to eject the molded product. Then, the ejector motor is driven to move the ejector rod 210 backward at the set moving speed, and the ejector plate 826 is moved backward to the original standby position.

[0067] The position and moving speed of the ejector rod 210 are detected using, for example, an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and sends a signal indicating the detection result to the control device 700. In addition, the ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod moving speed detector that detects the moving speed of the ejector rod 210 are not limited to the ejector motor encoder, and a general detector can be used.

[0068] (Injection device)

[0069] In the description of the injection device 300, unlike the description of the mold clamping device 100 or the description of the ejection device 200, the moving direction of the screw 330 during filling (for example, the negative direction of the X-axis) is set to the front and the moving direction of the screw 330 during metering (for example, the positive direction of the X-axis) is set to the rear.

[0070] The injection device 300 is provided on a sliding base 301, and the sliding base 301 is configured to be able to move forward and backward relative to the injection device frame 920. The injection device 300 is configured to be able to move forward and backward relative to the mold device 800. The injection device 300 contacts the mold device 800 and fills the molding material into the cavity space 801 in the mold device 800. The injection device 300 includes, for example: a cylinder 310 for heating the molding material; a nozzle 320 provided at the front end of the cylinder 310; a screw 330 configured to be able to move forward and backward and rotate freely in the cylinder 310; a metering motor 340 for rotating the screw 330; an injection motor 350 for moving the screw 330 forward and backward; and a load detector 360 for detecting the load transmitted between the injection motor 350 and the screw 330.

[0071] The cylinder 310 heats the molding material supplied from the supply port 311. The molding material includes, for example, resin. The molding material is formed into, for example, granules and supplied to the supply port 311 in a solid state. The supply port 311 is formed at the rear of the cylinder 310. A cooler 312 such as a water-cooled cylinder is provided on the outer periphery of the rear of the cylinder 310. A first heater 313 such as a belt heater and a first temperature detector 314 are provided on the outer periphery of the cylinder 310 in front of the cooler 312.

[0072] The cylinder 310 is divided into a plurality of regions in the axial direction (e.g., X-axis direction) of the cylinder 310. The first heater 313 and the first temperature detector 314 are respectively provided in the plurality of regions. The set temperature is respectively set in the plurality of regions, and the control device 700 controls the first heater 313 so that the detection temperature of the first temperature detector 314 becomes the set temperature.

[0073] The nozzle 320 is set 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.

[0074] The screw 330 is arranged in the cylinder 310 so as to be rotatable and to be able to move forward and backward. When the screw 330 is rotated, the molding material is sent forward along the spiral groove of the screw 330. While the molding material is sent forward, it is gradually melted by the heat from the cylinder 310. As the liquid molding material is sent forward to the front of the screw 330 and accumulated in the front part of the cylinder 310, the screw 330 moves backward. Then, when the screw 330 is moved forward, the liquid molding material accumulated in front of the screw 330 is ejected from the nozzle 320 and filled into the mold device 800.

[0075] At the front part of the screw 330, a backflow prevention ring 331 is movably mounted 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.

[0076] When the screw 330 is advanced, the backflow prevention ring 331 is pushed backward by the pressure of the molding material in front of the screw 330, and retreats relative to the screw 330 to a closed position that blocks the flow path of the molding material (see Figure 2 ). Thus, the molding material accumulated in front of the screw 330 is prevented from flowing backward.

[0077] 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 conveyed forward along the spiral groove of the screw 330, and moves forward relative to the screw 330 to an open position (refer to Figure 1 ). As a result, the molding material is transported to the front of the screw 330.

[0078] The backflow prevention ring 331 may be of 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 .

[0079] In addition, the injection device 300 may include a driving source that moves the backflow prevention ring 331 forward and backward relative to the screw 330 between the open position and the closed position.

[0080] The metering motor 340 rotates the screw 330. The driving source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump or the like.

[0081] The injection motor 350 moves the screw 330 forward and backward. A motion conversion mechanism that converts the rotational motion of the injection motor 350 into the linear motion of the screw 330 is provided between the injection motor 350 and the screw 330. The motion conversion mechanism includes, for example, a screw shaft and a screw nut screwed with the screw shaft. A ball or roller may be provided between the screw shaft and the screw nut. The driving source that moves the screw 330 forward and backward is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder.

[0082] 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.

[0083] 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 a pressure acting between the screw 330 and the molding material, and is used to control or monitor the pressure applied to the molding material to the screw 330, the back pressure on the screw 330, and the pressure acting on the molding material from the screw 330.

[0084] In addition, the pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a common detector can be used. For example, a nozzle pressure sensor or a mold internal pressure sensor can also be used. The nozzle pressure sensor is provided at the nozzle 320. The mold internal pressure sensor is provided inside the mold device 800.

[0085] The injection device 300 performs a metering process, a filling process, a pressure-maintaining process, etc. under the control of the control device 700. The filling process and the pressure-maintaining process can be collectively referred to as an injection process.

[0086] In the metering process, the metering motor 340 is driven to rotate the screw 330 at a set speed, and the molding material is transported to the front along the spiral groove of the screw 330. As a result, the molding material gradually melts. As the liquid molding material is transported to the front of the screw 330 and accumulated in the front part of the cylinder 310, the screw 330 retreats. The rotation speed of the screw 330 is detected using, for example, 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. In addition, the screw rotation speed detector that detects the rotation speed of the screw 330 is not limited to the metering motor encoder 341, and a common screw rotation speed detector can be used.

[0087] In order to prevent the screw 330 from retreating rapidly during the metering process, the injection motor 350 may be driven to apply a set back pressure to the screw 330. The back pressure on the screw 330 is detected, for example, using a load detector 360. When the screw 330 retreats to the metering completion position and a predetermined amount of molding material is accumulated in front of the screw 330, the metering process is completed.

[0088] The position and speed of the screw 330 in the metering process are set together as a series of setting conditions. For example, the metering start position, the speed switching position and the metering completion position are set. These positions are arranged in sequence from the front to the back, indicating the starting point and end point of the interval for setting the speed. The speed is set in each interval. The speed switching position can be one or more. The speed switching position can also be not set. In addition, a back pressure is set in each interval.

[0089] In the filling process, the injection motor 350 is driven to move the screw 330 forward at a set moving speed, so that the liquid molding material accumulated in front of the screw 330 is filled in 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. If the position of the screw 330 reaches the set position, a switch is made from the filling process to the pressure holding process (so-called V / P switching). The position where the V / P switching is performed is also referred to as the V / P switching position. The set moving speed of the screw 330 can be changed according to the position and time of the screw 330.

[0090] The position and moving speed of the screw 330 in the filling process are set together as a series of setting conditions. For example, the filling start position (also called the "injection start position"), the moving speed switching position and the V / P switching position are set. These positions are arranged in sequence from the back to the front, indicating the starting point and end point of the interval for setting the moving speed. The moving speed is set in each interval. The moving speed switching position can be one or more. The moving speed switching position can also be not set.

[0091] The upper limit value of the pressure of the screw 330 is set in each interval of setting the moving speed of the screw 330. The pressure of the screw 330 is detected by the load detector 360. When the pressure of the screw 330 is below the set pressure, the screw 330 moves forward at the set moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 moves forward at a moving speed slower than the set moving speed for the purpose of protecting the mold so that the pressure of the screw 330 becomes below the set pressure.

[0092] In addition, in the filling process, after the position of the screw 330 reaches the V / P switching position, the screw 330 may be temporarily stopped at the V / P switching position, and then the V / P switching may be performed. Instead of stopping the screw 330, the screw 330 may be moved forward or backward at a slow speed just before the V / P switching. Furthermore, the screw position detector for detecting the position of the screw 330 and the screw moving speed detector for detecting the moving speed of the screw 330 are not limited to the injection motor encoder 351, and a common screw position detector may be used.

[0093] In the pressure holding process, the injection motor 350 is driven to push the screw 330 forward, and the pressure of the molding material in the front end of the screw 330 (hereinafter also referred to as "holding pressure") is maintained at a set pressure, and the molding material remaining in the cylinder 310 is pushed toward the mold device 800. The insufficient molding material due to cooling shrinkage in the mold device 800 can be supplemented. The holding pressure is detected using a load detector 360, for example. The setting value of the holding pressure can be changed according to the elapsed time from the start of the pressure holding process. The holding pressure in the pressure holding process and the holding time for maintaining the holding pressure can be set separately in multiples, or can be set together as a series of setting conditions.

[0094] In the pressure holding process, the molding material in the cavity space 801 in the mold device 800 is gradually cooled. When the pressure holding process is completed, the entrance of the cavity space 801 is blocked by the solidified molding material. This state is called gate sealing, which prevents the molding material from flowing back from the cavity space 801. After the pressure holding process, the cooling process begins. The molding material in the cavity space 801 is solidified in the cooling process. In order to shorten the molding cycle time, a metering process can be performed in the cooling process.

[0095] In addition, the injection device 300 of this embodiment is a coaxial screw type, but it can also be a screw pre-plasticization type. The pre-plasticization type injection device supplies the molding material melted in the plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into the mold device. In the plasticizing cylinder, the screw is configured to be able to rotate freely and cannot move forward or backward, or the screw is configured to rotate freely and move forward and backward freely. On the other hand, in the injection cylinder, the plunger is configured to move forward and backward freely.

[0096] Furthermore, the injection device 300 of the present embodiment is a horizontal type in which the axial direction of the cylinder 310 is in the horizontal direction, but it may be a vertical type in which the axial direction of the cylinder 310 is in the up-down direction. The mold clamping device combined with the vertical injection device 300 may be a vertical type or a horizontal type. Similarly, the mold clamping device combined with the horizontal injection device 300 may be a horizontal type or a vertical type.

[0097] (Mobile device)

[0098] In the description of the moving device 400, similar to the description of the injection device 300, the moving direction of the screw 330 during filling (for example, the negative direction of the X axis) is set to the front and the moving direction of the screw 330 during metering (for example, the positive direction of the X axis) is set to the rear.

[0099] The moving device 400 moves the injection device 300 forward and backward relative to the mold device 800. In addition, the moving device 400 presses the nozzle 320 against the mold device 800 to generate nozzle contact pressure. The moving device 400 includes a hydraulic pump 410, a motor 420 as a driving source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

[0100] The hydraulic pump 410 has a first port 411 and a second port 412. The hydraulic pump 410 is a bidirectionally rotatable pump, and by switching the rotation direction of the motor 420, the hydraulic pump 410 sucks working fluid (for example, oil) from one of the first port 411 and the second port 412 and discharges it from the other to generate hydraulic pressure. Alternatively, the hydraulic pump 410 can also suck working fluid from a tank and discharge the working fluid from one of the first port 411 and the second port 412.

[0101] The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 with a rotation direction and torque corresponding to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servomotor.

[0102] 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.

[0103] The front chamber 435 of the hydraulic cylinder 430 is connected to the first port 411 of the hydraulic pump 410 via the first flow path 401. The working fluid discharged from the first port 411 is supplied to the front chamber 435 via the first flow path 401, thereby pushing the injection device 300 forward. The injection device 300 moves forward, and the nozzle 320 is pressed against the fixed mold 810. The front chamber 435 functions as a pressure chamber that generates the nozzle contact pressure of the nozzle 320 by the pressure of the working fluid supplied from the hydraulic pump 410.

[0104] On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the second port 412 of the hydraulic pump 410 via the second flow path 402. The hydraulic fluid discharged from the second port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the second flow path 402, thereby pushing the injection device 300 backward. The injection device 300 retreats, and the nozzle 320 is separated from the fixed mold 810.

[0105] In this embodiment, the moving device 400 includes the hydraulic cylinder 430 , but the present invention is not limited thereto. For example, 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 instead of the hydraulic cylinder 430 .

[0106] (Control device)

[0107] The control device 700 is constituted by a computer, for example. Figure 1-2 As shown, the control device 700 includes a CPU (Central Processing Unit) 701, a storage medium such as a memory 702, an input interface 703, and an output interface 704. The control device 700 performs various controls by causing the CPU 701 to execute a program stored in the storage medium 702. In addition, the control device 700 receives signals from the outside through the input interface 703 and sends signals to the outside through the output interface 704.

[0108] The control device 700 repeatedly manufactures molded products by repeatedly performing metering steps, mold closing steps, pressure increasing steps, mold clamping steps, filling steps, pressure holding steps, cooling steps, pressure releasing steps, mold opening steps, and ejection steps. A series of actions for obtaining molded products, such as the actions from the start of a metering step to the start of the next metering step, are also referred to as "injection" or "molding cycle". In addition, the time required for one injection is also referred to as "molding cycle time" or "cycle time".

[0109] A molding cycle, for example, includes a metering process, a mold closing process, a pressure increasing process, a mold closing process, a filling process, a pressure holding process, a cooling process, a pressure releasing process, a mold opening process, and an ejection process in sequence. The order here is the order in which each process starts. The filling process, the pressure holding process, and the cooling process are performed during the mold closing process. The start of the mold closing process can coincide with the start of the filling process. The completion of the pressure releasing process coincides with the start of the mold opening process.

[0110] In addition, in order to shorten the molding cycle time, multiple processes can be performed simultaneously. For example, the metering process can be performed in the cooling process of the previous molding cycle, or during the mold closing process. In this case, the mold closing process can be performed at the very beginning of the molding cycle. Furthermore, the filling process can be started in the mold closing process. Furthermore, the ejection process can be started in the mold opening process. In the case of an on-off valve that opens and closes the flow path of the nozzle 320, the mold opening process can be started in the metering process. This is because, even if the mold opening process is started in the metering process, if the on-off valve closes the flow path of the nozzle 320, the molding material will not leak from the nozzle 320.

[0111] In addition, a primary molding cycle may include processes other than the metering process, the mold closing process, the pressure increasing process, the mold clamping process, the filling process, the pressure holding process, the cooling process, the pressure releasing process, the mold opening process, and the ejection process.

[0112] For example, after the pressure holding process is completed and before the metering process begins, a pre-metering suction process can be performed to retract the screw 330 to a preset metering start position. The pressure of the molding material accumulated in front of the screw 330 can be reduced before the metering process begins, and the screw 330 can be prevented from retreating sharply when the metering process begins.

[0113] Furthermore, after the metering process is completed and before the filling process begins, a post-metering backsucking process may be performed in which the screw 330 is retracted to a preset filling start position (also referred to as an "injection start position"). The pressure of the molding material accumulated in front of the screw 330 can be reduced before the filling process begins, and the molding material can be prevented from leaking from the nozzle 320 before the filling process begins.

[0114] The control device 700 is connected to an operation device 750 that receives input operations from a user or a display device 760 that displays a screen. The operation device 750 and the display device 760 may be formed of, for example, a touch panel 770 and integrated. The touch panel 770 as the display device 760 displays a screen under the control of the control device 700. On the screen of the touch panel 770, for example, information such as the settings of the injection molding machine 10 and the current state of the injection molding machine 10 may be displayed. In addition, on the screen of the touch panel 770, for example, operation parts such as buttons and input fields that receive input operations from a user may be displayed. The touch panel 770 as the operation device 750 detects the input operation of the user on the screen and outputs a signal corresponding to the input operation to the control device 700. Thus, for example, the user can operate the operation part set on the screen while confirming the information displayed on the screen to perform settings of the injection molding machine 10 (including input of a set value). In addition, by the user operating the operation part set on the screen, the injection molding machine 10 corresponding to the operation part can be operated. In addition, the operation of the injection molding machine 10 may be, for example, the operation (including stopping) of the mold clamping device 100, the ejection device 200, the injection device 300, the moving device 400, etc. Furthermore, the operation of the injection molding machine 10 may be the switching of the screen displayed on the touch panel 770 as the display device 760, etc.

[0115] In addition, the operating device 750 and the display device 760 of this embodiment are described as being integrated into a touch panel 770, but they may be provided independently. In addition, a plurality of operating devices 750 may be provided. The operating device 750 and the display device 760 are arranged on the operating side (negative direction of the Y axis) of the mold clamping device 100 (more specifically, the fixed platen 110).

[0116] (Detailed description of injection device)

[0117] Next, refer to Figure 3 An example of the cylinder 310 and the screw 330 will be described. Figure 3 In the figure, the right is the rear and the left is the front. The injection device 300 includes, for example, a cylinder 310 having a supply port 311 for molding material; a first heater 313 for heating the cylinder 310; a screw 330 disposed inside the cylinder 310; and a spiral groove 334 disposed on the outer periphery of the screw 330. The injection device 300 transports the molding material from the rear to the front along the spiral groove 334 by rotating the screw 330. The rear is the upstream and the front is the downstream.

[0118] The cylinder 310 is divided into a plurality of (e.g., five) zones Z0 to Z4 along the axial direction (e.g., X-axis direction) of the cylinder 310. A cooler 312 is provided in the zone Z0 on the most upstream side, and a first heater 313 and a first temperature detector 314 are provided in each of the remaining zones Z1 to Z4. Set temperatures are set in each of the zones Z0 to Z4. In addition, the number of zones may be two or more, and is not limited to five.

[0119] The control device 700 performs feedback control on the temperature of the refrigerant supplied from the refrigerant supplier 315 to the cooler 312 so that the actual temperature of the 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 particles of the molding material melt and become clogged. The cooler 312 is, for example, a water-cooled cylinder. The cooler 312 or the refrigerant supplier 315 may have a temperature detector.

[0120] Furthermore, the control device 700 detects the actual temperature of each of the plurality of zones Z1 to Z4 by the first temperature detector 314, and performs feedback control on the output of the first heater 313 for each zone Z1 to Z4 so that the actual temperature detected by the first temperature detector 314 becomes the set temperature. The plurality of first heaters 313 may have the same structure or different structures. The first heater 313 is, for example, a belt heater.

[0121] The output of the first heater 313 is represented, for example, by a ratio (%) of the power-on time per unit time. The greater the ratio of the power-on time, the greater the output of the first heater 313. In addition, although not shown in the figure, when a plurality of first heaters 313 are provided in one area, the ratio of the power-on time of the plurality of first heaters 313 is controlled to be the same ratio. Furthermore, although not shown in the figure, a plurality of first temperature detectors 314 may be provided in one area. The number of areas, the number of first heaters 313, and the number of first temperature detectors 314 may be inconsistent.

[0122] A nozzle 320 is provided at the front end of the cylinder 310. The nozzle 320 is pressed against the mold device 800 (refer to Figure 1 and Figure 2 ), and injects the pre-melted molding material into the interior of the mold device 800. A second heater 323 and a second temperature detector 324 are provided on the periphery of the nozzle 320. The second heater 323 and the second temperature detector 324 are provided in the zone Z5.

[0123] The control device 700 detects the actual temperature of the zone Z5 by the second temperature detector 324, and performs feedback control on 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. The output of the second heater 323 is represented, for example, by a ratio (%) of the power-on time per unit time.

[0124] In addition, the nozzle 320 may be divided into a plurality of regions along the X-axis direction similarly to the cylinder 310. The second heater 323 and the second temperature detector 324 are respectively provided in the plurality of regions. In this case, the control device 700 performs feedback control on the output of the second heater 323 for each region separately. The plurality of second heaters 323 may have the same structure or different structures.

[0125] The screw 330 is rotatably and reciprocatably arranged in the cylinder 310. When the metering motor 340 rotates the screw 330, the molding material is fed forward along the spiral groove 334. The molding material is gradually melted by the heat from the cylinder 310 while being fed forward.

[0126] As the liquid molding material is transported to the front of the screw 330 and accumulated in the front part of the cylinder 310, the screw 330 retreats. Then, if the injection motor 350 advances the screw 330, the liquid molding material accumulated in front of the screw 330 is ejected from the nozzle 320 and filled in the mold device 800.

[0127] Next, refer to Figure 4 An example of the screw 330 is described. The screw 330 has a rotation axis 332 and a thread 333 that is spirally arranged around the rotation axis 332. The pitch of the thread 333 is constant in this embodiment, but it may not be constant. A spiral groove 334 is formed along the thread 333. When the metering motor 340 rotates the screw 330, the molding material is fed from the rear to the front along the spiral groove 334.

[0128] The screw 330 is supplied from the supply port 311 (see Figure 3 ) has a supply section X1, a compression section X2 and a metering section X3 in sequence toward the front. The supply section X1 is a region where particles of the molding material are kept in a solid state and transported forward. The compression section X2 is a region where the molding material is compressed and the molding material is transported forward while being melted. The metering section X3 is a region where the molten molding material is transported forward.

[0129] The depth of the groove 334 in the supply section X1 is constant. The depth of the groove 334 in the supply section X1 is equal to the depth D1 of the groove 334 in the rear end X2b of the compression section X2. The rear end X2b of the compression section X2 is the entrance of the molding material in the compression section X2. The depth of the groove 334 in the compression section X2 becomes shallower from the front end of the supply section X1 toward the front. The depth of the groove 334 in the metering section X3 is constant. The depth of the groove 334 in the metering section X3 is equal to the depth D2 of the groove 334 in the front end X2a of the compression section X2. The front end X2a of the compression section X2 is the exit of the molding material in the compression section X2. The ratio of D1 to D2 (D1 / D2) is called the compression ratio.

[0130] In addition, the structure of screw 330 is not particularly limited. For example, between compression section X2 and metering section X3, there may be a second compression section not shown. The variation of the depth of the groove 334 of each pitch of the second compression section and the compression section X2 may be the same or different. In the former case, between the second compression section and the compression section X2, there may be an intermediate portion with a constant depth of the groove 334. In the latter case, there may be no intermediate portion, and the second compression section and the compression section X2 may be continuously connected. In any case, when there is a second compression section between compression section X2 and metering section X3, the depth of the groove 334 in metering section X3 is less than D2.

[0131] like Figure 3 As shown, when the screw 330 is located at the forward limit position, the rear end X2b of the compression section X2 is located in the first heater 313 that is further forward than the supply port 311, and is further forward than the rear end of the rearmost first heater 313 (i.e., the rear end Z1b of the zone Z1). Before the molding material reaches the rear end X2b of the compression section X2, the molding material reaches the rear end Z1b of the zone Z1. Therefore, after the molding material is properly heated in the supply section X1, it enters the compression section X2. In addition, although not shown in the figure, when the screw 330 is located at the forward limit position, the rear end X2b of the compression section X2 may also be located at the same position as the rear end Z1b of the zone Z1.

[0132] The forward limit position of the screw 330 is a position that becomes a reference position of the buffer position. The buffer position is a position when the screw 330 advances the most during the injection process. The buffer position is a position further back than the forward limit position or the same position as the forward limit position. The molding conditions are set in such a way that the buffer position falls within a set range from the forward limit position. If the buffer position reaches the forward limit position, the screw 330 may collide with the nozzle 320, so the control device 700 stops the advancement of the screw 330.

[0133] Next, refer to Figure 3 and Figure 4 as well as Figure 5, the relationship between the structure of the screw 330 and the deviation of the metering time is described. The deviation of the metering time indicates the deviation of at least one of the temperature, viscosity and density of the liquid molding material accumulated in front of the screw 330 inside the cylinder 310. These deviations may lead to the quality deviation of the molded product.

[0134] The deviation of the metering time is significant when using a crystalline resin as a molding material. Crystalline resins are different from amorphous resins and have a melting point. The viscosity of crystalline resins changes sharply with the melting point as the boundary. Therefore, the deviation of the metering time of crystalline resins tends to become larger. Among crystalline resins, the viscosity of LCP resins (liquid crystal polymers) tends to become lower when the temperature reaches the melting point, and the deviation of the metering time tends to become larger.

[0135] In order to reduce the deviation of metering time, the inventors of the present invention focus on the following (D1 / D0), (D1 / D2) and (V1 / V2). D0 is the diameter of the screw 330. D0 is constant. D1 is the depth of the groove 334 in the rear end X2b of the compression section X2. D1 is equal to the depth of the groove 334 in the supply section X1. D2 is the depth of the groove 334 in the front end X2a of the compression section X2. The depth of D2 is equal to the depth of the groove 334 in the metering section X3. However, in the case where there is a second compression section (not shown) between the compression section X2 and the metering section X3, D2 is greater than the depth of the groove 334 in the metering section X3. In addition, V1 and V2 will be described later.

[0136] (D1 / D0) represents the ratio of the volume of the groove 334 in the supply portion X1 to the volume of the cylinder 310. The larger (D1 / D0) is, the larger the ratio of the volume of the groove 334 is. (D1 / D0) is, for example, 0.140 or more and 0.260 or less. If (D1 / D0) is 0.140 or more, the particles P of the molding material easily enter the groove 334 in the supply port 311 of the cylinder 310. And, if (D1 / D0) is 0.260 or less, the rigidity of the screw 330 is reduced less due to the formation of the groove 334, and the durability of the screw 330 to the injection pressure of the molding material is good.

[0137] If (D1 / D0) is greater than 0.140, then Figure 5 As shown in FIG. 1 , the depth of the groove 334 in the supply portion X1 is deep, and a large amount of particles P can be accommodated inside the groove 334. The particles P are melted by the heat from the cylinder 310. As a result, a molten film M may be generated on the inner periphery of the cylinder 310. The amount of the molten film M does not depend on the depth of the groove 334. Therefore, in the supply portion X1, the deeper the depth of the groove 334, the smaller the ratio of the amount of the molten film M to the amount of the particles P.

[0138] If the melt film M is generated, the pellets P are likely to slide relative to the inner circumference of the cylinder 310. If the ratio of the amount of the melt film M is too large, the pellets P rotate together with the screw 330, and cannot be fed forward. If (D1 / D0) is greater than 0.140, the ratio of the amount of the melt film M to the amount of the pellets P is small in the supply section X1. Therefore, if (D1 / D0) is greater than 0.140, the pellets P can be stably fed forward in the supply section X1, and the deviation of the metering time can be reduced.

[0139] Furthermore, if (D1 / D0) is greater than 0.140, then Figure 5 As shown by arrow A in , even if the liquid resin flows back from the metering section X3 and the compression section X2 to the supply section X1, the proportion of the amount of liquid resin in the gaps between the particles P is small. If this proportion is too large, the liquid resin hinders the contact between the particles P and the inner circumference of the cylinder body 310, so the particles P cannot be stably fed to the front. If (D1 / D0) is greater than 0.140, the particles P can be strongly pressed against the inner circumference of the body 310. As a result, the friction between the cylinder body 310 and the particles P is enhanced, and the particles P will not rotate with the screw 330, but will be fed to the front. The particles P can be stably fed to the front in the supply section X1, and the deviation of the metering time can be reduced.

[0140] (D1 / D2) represents the amount of change in the depth of the groove 334 in the compression section X2. The larger (D1 / D2) is, the greater the amount of change in the depth of the groove 334 in the compression section X2 is. (D1 / D2) is, for example, 2.50 or more. If (D1 / D2) is 2.50 or more, the depth D1 of the groove 334 in the supply section X1 is large enough. Therefore, in the supply section X1, the ratio of the amount of the molten film M to the amount of the particles P is small, and the ratio of the amount of the liquid resin in the gaps between the particles P is small. Therefore, the particles P can be stably fed to the front in the supply section X1, and the deviation of the metering time can be reduced.

[0141] (D1 / D2) is, for example, less than 3.80. If (D1 / D2) is less than 3.80, the depth of the groove 334 in the metering section X3 is sufficiently small. Therefore, when a portion of the molding material flows into the metering section X3 while maintaining a solid state, the solid-phase molding material can be fully compressed and sheared in the metering section X3. Therefore, the solid-phase molding material can be melted by the heat caused by the shear stress. The fully melted molding material can be accumulated in front of the screw 330, and the quality degradation of the molded product can be suppressed.

[0142] In order to reduce the deviation of the measurement time, the present inventors also focus on the following (V1 / V2). Figure 3 As shown, V1 is the volume of the groove 334 from the rear end Z1b of the zone Z1 to the rear end X2b of the compression section X2 when the screw 330 is at the forward limit position. Figure 3 As shown, V2 is the volume of the slot 334 of the supply portion X1 at the rear end Z1b of the region Z1 when the screw 330 is at the forward limit position. The volume of the slot 334 of one pitch is measured between two adjacent upper ends of the screw blade 333 in the X-axis direction.

[0143] (V1 / V2) represents the time T1 from when the particles P start to be heated to when the particles P start to be compressed. The larger (V1 / V2), the longer the time T1. (V1 / V2) is, for example, greater than 0.00 and less than 12.50. If (V1 / V2) is less than 12.50, the time T1 is short, and the particles P begin to be compressed before they are completely melted by the heat. The particles P maintain their granular shape. Therefore, in the compression section X2, the particles P can be strongly pressed against the inner circumference of the cylinder 310. As a result, the friction between the cylinder 310 and the particles P is enhanced, and the particles P will not rotate with the screw 330, but will be sent to the front. The particles P can be stably sent to the front, and the deviation of the metering time can be reduced.

[0144] In addition, when (V1 / V2) is less than 0.00, that is, when the rear end X2b of the compression section X2 is located further back than the rear end Z1b of the zone Z1, the particles P begin to be compressed before the particles P begin to be heated. At this time, in the compression section X2, the particles P are blocked due to being too hard. As a result, the screw 330 is strongly pushed back to the rear. In this way, the control device 700 quickly retreats the screw 330 in order to maintain the back pressure of the screw 330 at a set value. Therefore, the metering time is shortened. In addition, if the particles P are blocked in the compression section X2, new particles P will not flow from the supply section X1 into the compression section X2, thereby causing the density of the molding material accumulated in front of the screw 330 to decrease. As a result, the quality of the molded product deteriorates.

[0145] According to this embodiment, since (V1 / V2) is 0.00 or more, clogging of the pellets P in the compression section X2 can be suppressed, and the metering time can be stabilized. In addition, the density of the molding material accumulated in front of the screw 330 can be suppressed from decreasing, and the quality of the molded product can be suppressed from decreasing.

[0146] (V1 / V2) is more preferably 0.00 or more and less than 9.50. If (V1 / V2) is less than 9.50, the pellets P can be more strongly pressed against the inner circumference of the cylinder 310 in the compression section X2, and the variation in the metering time can be further reduced.

[0147] Next, refer to Figure 6 and Figure 7 The experimental data are explained. In Examples 1 to 3, except for Figure 6In addition to D1, (D1 / D0), (D1 / D2) and (V1 / V2) shown in the figure, a screw 330 with the same structure was also produced, and the deviation of the metering time was measured five times. Each time, 19 injections were performed. The deviation of the metering time was evaluated by the standard deviation σ (unit: sec (seconds)) in the 19 injections. Figure 6 In , σave is the average value of σ. Figure 7 In FIG. 1 , the vertical axis is σ, which indicates the deviation of σ of the screw 330. Example 1 is a comparative example, and Examples 2 and 3 are examples.

[0148] Comparison of Examples 1 and 2 clearly shows that if (D1 / D0) is 0.140 or more and 0.260 or less, and (D1 / D2) is 2.50 or more and 3.80 or less, the standard deviation σ of the metering time is small. Comparison of Examples 2 and 3 clearly shows that the smaller (V1 / V2) is, the smaller the standard deviation σ of the metering time is. If (V1 / V2) is less than 9.50, the standard deviation σ of the metering time is particularly small.

[0149] The above is an explanation of the embodiments of the injection molding machine involved in the present invention, but the present invention is not limited to the above embodiments, etc. Various changes, modifications, replacements, additions, deletions and combinations can be made within the scope of the technical solution. These contents certainly also fall within the technical scope of the present invention.

Claims

1. An injection molding machine, comprising: a cylinder having a supply port for molding material; a heater for heating the cylinder; a screw disposed inside the cylinder; and a spiral groove formed on the outer periphery of the screw, wherein the injection molding machine transports the molding material from the rear to the front along the groove by rotating the screw, wherein: The screw has, in order from the supply port toward the front: a supply portion, in which the depth of the groove is constant; and a compression portion, in which the depth of the groove becomes shallower as it moves toward the front from the front end of the supply portion. If the diameter of the screw is D0, the depth of the groove at the rear end of the compression portion is D1, and the depth of the groove at the front end of the compression portion is D2, then (1) D1 / D0 is greater than or equal to 0.140 and less than or equal to 0.260, and (2) D1 / D2 is greater than or equal to 2.50 and less than or equal to 3.80, When the screw is at the forward limit position, the rear end of the compression portion is at the same position as or in front of the rear end of the heater that is rearward of the supply port. If the volume of the groove from the rear end of the rearmost heater to the rear end of the compression section when the screw is in the forward limit position is set to V1, and the volume of the groove of one pitch of the supply section at the rear end of the rearmost heater when the screw is in the forward limit position is set to V2, then (3) V1 / V2 is greater than 0.00 and less than 12.

50.

2. The injection molding machine according to claim 1, wherein: V1 / V2 is greater than or equal to 0.00 and less than 9.50.

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