Nozzle for injection molding machine, and injection molding machine

Abstract

To provide technology for suppressing unintentional leakage of molding material from a nozzle.SOLUTION: A nozzle for an injection molding machine has a flow path formed therein through which a molding material flows from rear to front. The flow path has, from rear to front, a first narrowed part, a straight part, a second narrowed part, and an outlet part, in this order, forward of a forward movement limit of a screw that pushes the molding material forward. The first narrowed part and the second narrowed part narrow a hole diameter forward, the straight part maintains the hole diameter forward, and the outlet part widens or maintains the hole diameter forward. The nozzle for the injection molding machine also has at least one of a heat insulating part that limits heat transfer in the nozzle and a cooling part that cools the nozzle, rearward of a boundary between the second narrowed part and the outlet part and forward of a heater that heats the nozzle.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a nozzle for an injection molding machine and an injection molding machine. [Background technology]

[0002] FIG. 3 of Patent Document 1 illustrates a nozzle for an injection molding machine. The nozzle is attached to the front end of a cylinder that heats a molding material. The molding material includes, for example, a resin. The cylinder heats and melts the molding material. The nozzle has an internal flow path through which the molding material flows from the rear to the front. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 07-060795 Summary of the Invention [Problem to be solved by the invention]

[0004] As shown in Figures 8 and 9, the flow path 321 of the nozzle 320 of the first conventional example has, from the rear side (right side in the figure) to the front side (left side in the figure), a straight section A1 and an outlet section A5, in this order. The straight section A1 maintains its hole diameter toward the front. The outlet section A5 widens its hole diameter toward the front. Although not shown, the outlet section A5 may maintain its hole diameter toward the front.

[0005] The front end of the nozzle 320 contacts the fixed mold 810. The fixed mold 810 and the movable mold 820 constitute a mold device 800. When the molds are clamped, a cavity space 801 is formed at the parting surface between the fixed mold 810 and the movable mold 820. The cavity space 801 is a space in which a molded article (product) is molded. In addition, a sprue space 802 is formed in the fixed mold 810.

[0006] 8, during mold clamping, molding material M injected forward from nozzle 320 passes through sprue space 802 and fills cavity space 801. The temperature of mold assembly 800 is lower than the temperature of nozzle 320, and molding material M solidifies inside mold assembly 800. At this time, molding material M at outlet A5 of nozzle 320 also solidifies.

[0007] Thereafter, the mold is opened as shown in Fig. 9. The solidified molding material MA moves together with the movable mold 820. Thereafter, the solidified molding material MA is ejected from the movable mold 820 by an ejector device (not shown).

[0008] 8 and 9, at the boundary between the straight portion A1 and the outlet portion A5, the hole diameter of the outlet portion A5 is smaller than the hole diameter of the straight portion A1, and the flow path 321 is sharply narrowed. As a result, when the mold is opened, the elongational viscosity of the molding materials M and MA is high at the boundary between the straight portion A1 and the outlet portion A5, which limits stress relaxation and makes the molding materials M and MA prone to tearing.

[0009] 8 and 9, if the flow path 321 is suddenly narrowed at the boundary between the straight portion A1 and the outlet portion A5, the molding material M will accumulate in the region B. The accumulation of the molding material M will lead to carbonization (so-called burning) of the molding material M. If the carbonized molding material M gets mixed into the molded product, the quality of the molded product will be reduced.

[0010] As shown in Figure 10, the flow path 321 of the nozzle 320 of the second conventional example has, from the rear side (right side in the figure) to the front side (left side in the figure), a straight section A1, a first narrowed section A2, and an outlet section A5, in this order. The first narrowed section A2 narrows its hole diameter toward the front. The side surface of the first narrowed section A2 has a gentle slope.

[0011] The first narrowed section A2 can prevent the molding material M from accumulating. However, the first narrowed section A2 makes it difficult to sufficiently increase the elongational viscosity of the molding material M, MA at the boundary between the straight section A1 and the outlet section A5 when the mold is opened. Because the elongational viscosity is low, stress relaxation is likely to occur, causing the molding material M to stretch into threads (so-called stringiness).

[0012] If the molding material M stretches into strings and adheres to the mold assembly 800, it may cause damage to the mold assembly 800 or a deterioration in the quality of the molded product. The phenomenon of the molding material M stretching into strings may occur not only when the mold is opened, but also when the nozzle 320 is separated from the fixed mold 810. The phenomenon of the molding material M stretching into strings when the nozzle 320 is separated from the fixed mold 810 is also called stringing and drooling.

[0013] One embodiment of the present invention provides a technique for suppressing unintentional leakage of molding material from a nozzle. [Means for solving the problem]

[0014] An injection molding machine nozzle according to one embodiment of the present invention has a flow path formed therein through which molding material flows from rear to front. The flow path has, from rear to front, a first narrowed portion, a straight portion, a second narrowed portion, and an outlet portion, in this order, forward of the forward movement limit of a screw that pushes the molding material forward. The first narrowed portion and the second narrowed portion narrow the hole diameter forward, the straight portion maintains the hole diameter forward, and the outlet portion widens or maintains the hole diameter forward. The injection molding machine nozzle also has at least one of an insulating portion that limits heat transfer in the nozzle and a cooling portion that cools the nozzle, located rearward of the boundary between the second narrowed portion and the outlet portion and forward of a heater that heats the nozzle. [Effects of the Invention]

[0015] According to one embodiment of the present invention, it is possible to suppress unintended leakage of molding material from the nozzle. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a state when mold opening of an injection molding machine according to one embodiment is completed. [Figure 2] FIG. 2 is a diagram showing a state of the injection molding machine according to one embodiment when clamping the mold. [Figure 3] FIG. 3 is a cross-sectional view showing an example of an injection device. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which the nozzle assembly according to one embodiment is clamped. [Figure 5] FIG. 5 is a cross-sectional view showing the nozzle assembly shown in FIG. 4 in a state where the mold is opened. [Figure 6] FIG. 6 is a cross-sectional view showing a nozzle assembly according to a first modified example. [Figure 7] FIG. 7 is a cross-sectional view showing a nozzle assembly according to a second modified example. [Figure 8] FIG. 8 is a cross-sectional view showing a state in which the nozzle assembly according to the first conventional example is clamped. [Figure 9] FIG. 9 is a cross-sectional view showing a state of the nozzle assembly according to the first conventional example when the mold is opened. [Figure 10] FIG. 10 is a cross-sectional view showing a nozzle assembly according to a second conventional example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals, and the description thereof may be omitted.

[0018] (injection molding machine) FIG. 1 is a diagram showing a state of an injection molding machine according to an embodiment when mold opening is completed. FIG. 2 is a diagram showing a state of an injection molding machine according to an embodiment 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.

[0019] As shown in FIGS. 1 and 2 , injection molding machine 10 includes a mold clamping unit 100 that opens and closes mold apparatus 800, an ejector unit 200 that ejects a molded product molded by mold apparatus 800, an injection unit 300 that injects molding material into mold apparatus 800, a moving unit 400 that moves injection unit 300 forward and backward relative to mold apparatus 800, a control unit 700 that controls each component of injection molding machine 10, and a frame 900 that supports each component of injection molding machine 10. Frame 900 includes a mold clamping unit frame 910 that supports mold clamping unit 10 and an injection unit frame 920 that supports injection unit 300. Clamping unit frame 910 and injection unit frame 920 are each installed on floor 2 via leveling adjusters 930. Control unit 700 is disposed in the interior space of injection unit frame 920. Each component of injection molding machine 10 will be described below.

[0020] (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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] In this embodiment, the fixed platen 110 is fixed to the mold clamping unit frame 910, and the toggle support 130 is arranged so as to be freely movable in the mold opening and closing direction relative to the mold clamping unit frame 910, but the toggle support 130 may also be fixed to the mold clamping unit frame 910, and the fixed platen 110 may be arranged so as to be freely movable in the mold opening and closing direction relative to the mold clamping unit frame 910.

[0028] 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.

[0029] 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.

[0030] 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 freely. The second link 153 is attached to the toggle support 130 by a pin or the like so that it can swing freely. 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 another part of the cavity space 801 may be filled with a molding material. A molded product is obtained in which the insert material and the molding material are integrated.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 mold closing completion position may be the same position. Furthermore, the mold opening completion position and mold closing start position may be the same position.

[0044] 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.

[0045] 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 is 180°, the toggle factor is maximum.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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, a drive gear is attached to the output shaft of the mold thickness adjustment motor 183, and 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.

[0050] 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.

[0051] The gap 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 gap L. Note that the toggle support position detector that detects the position of the toggle support 130 and the gap detector that detects the gap L are not limited to the mold thickness adjustment motor encoder 184, and general detectors can be used.

[0052] 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.

[0053] 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.

[0054] Although the mold clamping unit 100 of this embodiment has a mold clamping motor 160 as a drive unit, it may have a hydraulic cylinder instead of the mold clamping motor 160. Also, the mold clamping unit 100 may have a linear motor for opening and closing the mold, and an electromagnet for mold clamping.

[0055] (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.

[0056] 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).

[0057] 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.

[0058] The drive mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts the rotational motion of the ejector motor into linear motion of the ejector rod 210. The motion conversion mechanism includes a screw shaft and a screw nut that screws onto the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

[0059] The ejector unit 200 performs an ejection process under the control of the control unit 700. In the ejection process, the ejector rod 210 is advanced from the standby position to the ejection position at a set moving speed, thereby advancing the ejector plate 826 and ejecting the molded product. After that, 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.

[0060] 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.

[0061] (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 forward direction, and the movement direction of the screw 330 during metering (e.g., the positive X-axis direction) is described as the rearward direction.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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 sent forward along the spiral groove of the screw 330. As 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 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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 any 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.

[0086] 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.

[0087] Although the injection device 300 of this embodiment is of an in-line screw type, it 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.

[0088] 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.

[0089] (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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] (Control device) The control device 700 is configured, for example, by a computer, and as shown in Figures 1 and 2, has a CPU (Central Processing Unit) 701, a storage medium 702 such as a memory, 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. 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.

[0098] The control device 700 includes electronic circuits such as a CPU, a Field Programmable Gate Array (FPGA), or an Application Specific Integrated Circuit (ASIC), 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.

[0099] 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, such as the operations from the start of a metering process to the start of the next metering process, is also called a "shot" or "molding cycle." The time required for one shot is also called the "molding cycle time" or "cycle time."

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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).

[0107] (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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] Next, the flow path 321 will be described in detail with reference to Fig. 4 and Fig. 5. Fig. 4 shows the state when the mold is clamped, and Fig. 5 shows the state when the mold is opened. In Fig. 4 and Fig. 5, M represents the molten molding material, and in Fig. 5, MA represents the solidified molding material.

[0119] The flow path 321 has, in this order from the rear to the front, a straight section A1, a first narrowed section A2, a straight section A3, a second narrowed section A4, and an outlet section A5 forward of the forward limit position (in other words, the pocket section A0) of the screw 330 (see FIG. 3). The straight sections A1 and A3 maintain the hole diameter forward. The first narrowed section A2 and the second narrowed section A4 narrow the hole diameter forward. The outlet section A5 widens or maintains the hole diameter forward.

[0120] The straight portion A1 has, for example, a cylindrical shape. The straight portion A1 is provided from the pocket portion A0 to the first narrowed portion A2 shown in FIG. 3, and adjusts the flow of the molding material M narrowed in the pocket portion A0 to a uniform flow toward the front. The flow path 321 may have a third narrowed portion (not shown) midway along the straight portion A1. The third narrowed portion narrows the hole diameter toward the front.

[0121] The first narrowed portion A2 has, for example, a truncated cone shape. The gradient of the side surface of the first narrowed portion A2 is constant. If the gradient of the side surface of the first narrowed portion A2 is constant, the flow of the molding material M can be gradually narrowed without causing the molding material M to stagnate. The inclination angle α of the side surface of the first narrowed portion A2 is not particularly limited, but is, for example, about 10°.

[0122] It is preferable that the entire first narrowed portion A2 overlaps with the second heater 323 in the front-to-rear direction. The second heater 323 can heat the entire first narrowed portion A2, preventing the molding material M from accumulating in the first narrowed portion A2. Accumulation of the molding material M can lead to carbonization (so-called burning) of the molding material M. If the carbonized molding material M gets mixed into the molded product, the quality of the molded product will be reduced.

[0123] The straight section A3 has, for example, a cylindrical shape. The straight section A3 is provided from the first narrowed section A2 to the second narrowed section A4, and adjusts the flow of the molding material M narrowed at the first narrowed section A2 into a uniform flow toward the front. The flow of the molding material M can be adjusted just before the second narrowed section A4. The length of the straight section A3 is preferably as short as possible, as long as it is possible to adjust the flow of the molding material M.

[0124] The second narrowed portion A4 has a shape similar to, for example, a cut-out portion of a sphere. The slope of the side surface of the second narrowed portion A4 becomes steeper toward the front. If the slope of the side surface of the second narrowed portion A4 becomes steeper toward the front, the molding material M can be rapidly compressed at the boundary between the second narrowed portion A4 and the outlet portion A5, and the elongational viscosity of the molding materials M and MA can be rapidly increased. Therefore, the molding materials M and MA are likely to break at the boundary between the second narrowed portion A4 and the outlet portion A5 when the mold is opened, for example.

[0125] The gradient of the side surface of the second narrowed portion A4 at its front end is steeper than the gradient of the side surface of the first narrowed portion A2. At the boundary between the second narrowed portion A4 and the outlet portion A5, the molding material M can be rapidly compressed, rapidly increasing the elongational viscosity of the molding materials M and MA. Therefore, the molding materials M and MA are likely to break at the boundary between the second narrowed portion A4 and the outlet portion A5 during mold opening, etc. The inclination angle β of the side surface of the second narrowed portion A4 at its front end is not particularly limited, but is, for example, approximately 70°. To increase the elongational viscosity of the molding materials M and MA at the boundary between the second narrowed portion A4 and the outlet portion A5, the inclination angle β is preferably greater than 60°, and the difference between the inclination angle β and the inclination angle α is preferably greater than 50°. The difference between the inclination angle α and the inclination angle β allows the molding material M to be rapidly compressed, rapidly increasing the elongational viscosity of the molding materials M and MA.

[0126] The gradient of the side surface of the second narrowed portion A4 at the rear end of the second narrowed portion A4 may also be steeper than the gradient of the side surface of the first narrowed portion A2. In other words, the gradient of the side surface of the second narrowed portion A4 may be steeper than the gradient of the side surface of the first narrowed portion A2 throughout the entire second narrowed portion A4. The inclination angle of the side surface of the second narrowed portion A4 at the rear end of the second narrowed portion A4 is not particularly limited, but is, for example, about 10°.

[0127] In this embodiment, the second narrowed portion A4 has a shape obtained by cutting out a portion of a sphere, but may have a truncated cone shape, similar to the first narrowed portion A2. The slope of the side surface of the second narrowed portion A4 may be constant. In this embodiment, a fillet is not provided at the boundary between the second narrowed portion A4 and the outlet portion A5, but a fillet may be provided. However, if a fillet is not provided, the molding materials M and MA are more likely to break at the boundary between the second narrowed portion A4 and the outlet portion A5 when the mold is opened, for example.

[0128] It is preferable that the entire second narrowed section A4 be located forward of the second heater 323. Compared to when part of the second narrowed section A4 overlaps the second heater 323 in the front-to-rear direction, the temperature of the molding material M is more easily reduced while passing through the second narrowed section A4, and the elongational viscosity of the molding materials M and MA can be increased at the boundary between the second narrowed section A4 and the outlet A5. Therefore, the molding materials M and MA are more likely to break at the boundary between the second narrowed section A4 and the outlet A5 when the mold is opened, etc.

[0129] The outlet portion A5 has, for example, a truncated cone shape. The outlet portion A5 widens its hole diameter toward the front. Therefore, when the mold is opened, the molding material MA solidified at the outlet portion A5 can be easily extracted forward from the outlet portion A5. The outlet portion A5 may have a cylindrical shape, and the outlet portion A5 may maintain its hole diameter toward the front. The outlet portion A5 only needs to have a hole diameter that does not narrow toward the front.

[0130] The nozzle assembly 303 includes a heat insulating portion 304 behind the boundary between the second narrowed portion A4 and the outlet portion A5 and ahead of the second heater 323. The heat insulating portion 304 limits the transfer of heat in the nozzle. The nozzle assembly 303 includes, for example, an annular groove 304A formed on the outer periphery of the nozzle 320 as the heat insulating portion 304.

[0131] The groove 304A forms an air layer. The air layer restricts the transfer of heat from the rear to the front of the groove 304A. This reduces the temperature of the molding materials M and MA at the boundary between the second narrowed portion A4 and the outlet portion A5, thereby increasing the elongational viscosity of the molding materials M and MA. The deeper the groove 304A, the better, as long as the nozzle 320 is not damaged by the pressure pressing the nozzle 320 against the fixed mold 810.

[0132] 4 and 5, the heat insulating section 304 is preferably located at the boundary between the second narrowed section A4 and the straight section A3 or behind the boundary, which facilitates lowering the temperature of the molding material M while passing through the second narrowed section A4, and can increase the elongational viscosity of the molding materials M, MA at the boundary between the second narrowed section A4 and the outlet section A5.

[0133] 6 or 7 instead of or in addition to the heat insulating section 304. The cooling section 305 cools the nozzle 320 behind the boundary between the second narrowed section A4 and the outlet section A5 and ahead of the second heater 323. The cooling section 305 can lower the temperature of the molding materials M, MA at the boundary between the second narrowed section A4 and the outlet section A5, thereby increasing the extensional viscosity of the molding materials M, MA.

[0134] The cooling section 305 is preferably located at the boundary between the second narrowed section A4 and the straight section A3 or behind that boundary, as shown in Figures 6 and 7. This makes it easier to lower the temperature of the molding material M while it passes through the second narrowed section A4, and it is possible to increase the elongational viscosity of the molding materials M, MA at the boundary between the second narrowed section A4 and the outlet section A5.

[0135] 6, the nozzle assembly 303 includes, as the cooling section 305, for example, an annular fin 305A formed on the outer periphery of the nozzle 320. The fin 305A cools the nozzle 320 by releasing heat from the nozzle 320 into the air. A plurality of fins 305A may be provided at intervals in the front-rear direction.

[0136] Alternatively, as shown in Fig. 7, the nozzle assembly 303 may include a pipe 305B, through which a coolant flows, around the outer periphery of the nozzle 320 as the cooling section 305. The coolant may be either a liquid such as water or oil, or a gas such as air. The coolant cools the nozzle 320 by receiving heat from the nozzle 320. The pipe 305B may be wound multiple times in a coil shape.

[0137] 4 to 7 can also be used with a hot runner. A nozzle 320 constituting the hot runner is provided inside a fixed mold 810 and faces a cavity space 801. The molding material flows into the cavity space 801 without passing through a sprue space 802. The nozzle assembly 303 may have a valve gate that opens and closes an outlet portion A5.

[0138] While the embodiments of the injection molding machine nozzle and injection molding machine according to the present invention have been described above, the present invention is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These changes also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0139] 320 nozzle 321 Channel 323 Second heater (heater) A2 1st stenosis A3 straight section A4 2nd stenosis A5 exit section

Claims

1. A nozzle for an injection molding machine, which has a flow path formed therein through which a molding material flows from rear to front, the flow path has, in this order from the rear side to the front side, a first narrowed portion, a straight portion, a second narrowed portion, and an outlet portion, ahead of a forward movement limit of a screw that pushes the molding material forward; the first narrowed portion and the second narrowed portion narrow the hole diameter toward the front, the straight portion maintains the hole diameter toward the front, and the outlet portion widens or maintains the hole diameter toward the front, a nozzle for an injection molding machine, comprising at least one of an insulating section that limits heat transfer in the nozzle and a cooling section that cools the nozzle, the insulating section being located rearward of the boundary between the second narrowed section and the outlet section and forward of a heater that heats the nozzle.

2. The nozzle for an injection molding machine according to claim 1 , wherein the first narrowed portion entirely overlaps the heater in the front-to-rear direction.

3. 2. The nozzle for an injection molding machine according to claim 1, wherein the second narrowed portion is entirely located in front of the heater.

4. 2. The nozzle for an injection molding machine according to claim 1, wherein the slope of the side surface of the first narrowed portion is constant.

5. The nozzle for an injection molding machine according to claim 1 , wherein the slope of the side surface of the second narrowed portion becomes steeper toward the front.

6. 2. The nozzle for an injection molding machine according to claim 1, wherein the slope of the side surface of the second narrowed portion at the front end of the second narrowed portion is steeper than the slope of the side surface of the first narrowed portion.

7. An injection molding machine comprising: the nozzle according to any one of claims 1 to 6; the heater that heats the nozzle; and a cylinder to which the nozzle is attached.

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