Manufacturing apparatus and manufacturing method of molded product

Abstract

To reduce molding defects in molded products.SOLUTION: A manufacturing apparatus of the present invention includes: an injection cylinder to which molten resin is fed and from which the molten resin is injected; and an injection plunger that is movable in a first direction and a second direction opposite to the first direction, and that is fitted and positioned in the injection cylinder, wherein the injection cylinder has a substrate for storing the molten resin inside and a sleeve detachable from the substrate, and the injection plunger is inserted inside the substrate through an opening provided in the sleeve and slides on the sleeve.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present disclosure relates to the manufacture of molded articles. [Background technology]

[0002] Generally, manufacturing devices that manufacture resin molded products by injection molding are known. In this type of manufacturing device, molten resin is injected into a cavity in a mold using a screw, plunger, etc., the molten resin is cooled and solidified in the mold, and after solidification, the mold is opened and the molded product is removed. Molded products are mass-produced by repeating a series of operations from injecting the molten resin to removing the molded product. For example, pre-plunger type and in-line screw type injection molding machines are known as manufacturing devices that perform injection molding.

[0003] Patent Document 1 discloses a pre-plunger type injection molding machine. The pre-plunger type injection molding machine includes a plasticizing section equipped with a plasticizing screw, an injection cylinder that stores plasticized and molten resin, an injection plunger that injects the molten resin stored in the injection cylinder, and a drive mechanism that drives the injection plunger. The injection plunger is driven to move forward and backward by the drive mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-261055 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional injection molding machines, for example, in the metering process or the suck back process, the injection plunger is forcibly retracted by the drive mechanism. When the injection plunger is forcibly retracted by the drive mechanism, a sudden pressure change occurs in the molten resin in the injection cylinder, and air may be entrained in the molten resin in the injection cylinder. If a molded product is manufactured in a state in which air is entrained in the molten resin, molding defects such as voids and silver streaks may occur in the molded product.

[0006] The present disclosure provides a technique that is advantageous in reducing molding defects in molded products. [Means for solving the problem]

[0007] A first aspect of the present disclosure is a manufacturing apparatus comprising: an injection cylinder supplied with molten resin and injecting the molten resin; an injection plunger fitted into the injection cylinder so as to be movable in a first direction and a second direction opposite to the first direction; and a pressing member that can be separated from the injection plunger and can press the injection plunger to move the injection plunger in the first direction, wherein the injection cylinder has a base that stores the molten resin therein and a sleeve that can be attached to and detached from the base, the injection plunger is inserted into the base through an opening provided in the sleeve and slides on the sleeve, and when the pressing member is separated from the injection plunger, the molten resin supplied to the injection cylinder presses the injection plunger, thereby moving the injection plunger in the second direction.

[0008] A second aspect of the present disclosure is a manufacturing apparatus comprising: an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger fitted into the injection cylinder and arranged to be movable in a first direction and a second direction opposite to the first direction; a pressing member that is movable away from the injection plunger and capable of pressing the injection plunger to move the injection plunger in the first direction; a drive source that is capable of driving the pressing member in the first direction and the second direction; and a control unit that is capable of controlling the driving source, wherein the injection cylinder has a base that stores the molten resin therein and a sleeve that is detachable from the base, the injection plunger is inserted into the base through an opening provided in the sleeve and slides on the sleeve, and the control unit controls the drive source to move the pressing member to a first position when metering the molten resin supplied to the injection cylinder. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a technique that is advantageous in reducing molding defects in molded products. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a schematic cross-sectional view of a manufacturing apparatus according to the first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of a method for manufacturing a molded product using the manufacturing apparatus according to the first embodiment. [Diagram 3] FIG. 2 is an explanatory diagram of a method for manufacturing a molded product using the manufacturing apparatus according to the first embodiment. [Figure 4] FIG. 2 is an explanatory diagram of a method for manufacturing a molded product using the manufacturing apparatus according to the first embodiment. [Diagram 5] FIG. 2 is an explanatory diagram of a method for manufacturing a molded product using the manufacturing apparatus according to the first embodiment. [Figure 6] 6A to 6C are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus according to a second embodiment. [Figure 7] 6A to 6C are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus according to a second embodiment. [Figure 8]6A to 6C are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus according to a second embodiment. [Figure 9] 6A to 6C are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus according to a second embodiment. [Figure 10] 11 is an explanatory diagram of a manufacturing method of a molded product using a manufacturing apparatus according to a third embodiment. FIG. [Figure 11] 11 is an explanatory diagram of a manufacturing method of a molded product using a manufacturing apparatus according to a third embodiment. FIG. [Figure 12] 11 is an explanatory diagram of a manufacturing method of a molded product using a manufacturing apparatus according to a third embodiment. FIG. [Figure 13] 1A is a schematic cross-sectional view of an injection cylinder, an injection plunger, and a pressing member of a manufacturing apparatus according to Modification 1. FIG. 1B is a schematic cross-sectional view of an injection cylinder, an injection plunger, and a pressing member of a manufacturing apparatus according to Modification 2. FIG. 1C is a schematic cross-sectional view of an injection cylinder, an injection plunger, and a pressing member of a manufacturing apparatus according to a fourth embodiment. [Figure 14] FIG. 13 is an explanatory view of a part of a manufacturing apparatus according to a fourth embodiment. [Figure 15] 13(a) and 13(b) are explanatory views of a part of a manufacturing apparatus according to a fourth embodiment. [Figure 16] FIG. 13 is a schematic cross-sectional view of a manufacturing apparatus according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] [First embodiment] FIG. 1 is a schematic cross-sectional view of a manufacturing apparatus 100 according to a first embodiment. The manufacturing apparatus 100 is a pre-plunger type injection molding apparatus, and is used to manufacture a resin molded product. The manufacturing apparatus 100 includes a plasticizing section 111, an injection section 112, a connecting unit 113 which is an example of a connecting section that connects the plasticizing section 111 and the injection section 112, and a control device 200. The control device 200 is an example of a control section, and is composed of one or more computers having a processor, for example. The control device 200 is capable of controlling the components included in the plasticizing section 111 and the injection section 112.

[0013] The plasticizing section 111 plasticizes the resin material introduced therein and supplies it to the injection section 112 via the connecting unit 113. The injection section 112 injects the molten resin supplied from the plasticizing section 111 into the mold 10 and supplies it inside the mold 10. When the mold 10 is clamped, a cavity CV is defined inside the mold 10. The cavity CV is a space corresponding to the shape of the molded product. The injection section 112 injects the molten resin to fill the cavity CV with the molten resin through the runner.

[0014] The plasticizing section 111 has a hopper (not shown), a plasticizing cylinder 121, a plasticizing screw 122, and a plasticizing drive section 123. For example, pellet-shaped resin material is fed into the hopper (not shown). The resin material is a thermoplastic resin. The plasticizing cylinder 121 is heated by a heater (not shown) to adjust the temperature to a temperature at which the supplied resin material is plasticized. A plasticizing screw 122 is disposed in the interior 126 of the plasticizing cylinder 121. The plasticizing screw 122 is a rotatable screw. The diameter of the plasticizing screw 122 is, for example, 20 mm.

[0015] The plasticizing drive unit 123 includes a drive source such as a motor, and is configured to rotate the plasticizing screw 122. The drive source of the plasticizing drive unit 123 is controlled by the control device 200. The plasticizing screw 122, when rotated by the plasticizing drive unit 123, moves the resin material supplied from a hopper (not shown) to the tip of the plasticizing screw 122 while plasticizing the resin material.

[0016] The injection unit 112 has an injection cylinder 141, an injection plunger 142, a switching valve 143, and an injection drive unit 144. The material of the injection cylinder 141 and the injection plunger 142 is preferably a metal. The metal is preferably, for example, a high-speed steel or a cemented carbide alloy.

[0017] The injection cylinder 141 has a supply port S through which molten resin is supplied, and a nozzle N through which the molten resin is injected. The nozzle N is an example of an injection port. In the first embodiment, the tip of the injection cylinder 141 in the direction of the axis C1 serves as the nozzle N. By bringing the nozzle N into contact with the mold 10, the interior 146 of the injection cylinder 141 and the cavity CV of the mold 10 are communicated with each other.

[0018] The plasticizing cylinder 121 and the injection cylinder 141 are connected via a connecting unit 113. The connecting unit 113 has a check valve 131 connected to the supply port S to prevent the molten resin from flowing back from the supply port S to the outside of the injection cylinder 141 (i.e., the plasticizing section 111). The check valve 131 is a valve that prevents the molten resin from flowing from the supply port S to the outside of the injection cylinder 141. The interior 126 of the plasticizing cylinder 121 and the interior 146 of the injection cylinder 141 are connected by a flow path PT1, and the check valve 131 is arranged in the flow path PT1. The connecting unit 113 has members 132 and 133 that define the flow path PT1. The check valve 131 is arranged inside the members 132 and 133. The check valve 131 has a ball 11, a valve seat 51 provided on the inflow side of the resin, and a valve claw 52 provided on the outflow side of the resin. The diameter of the ball 11 is, for example, 8 mm.

[0019] The check valve 131 is connected to the supply port S in such a direction that the molten resin does not flow back from the injection cylinder 141 to the plasticizing screw 122. By arranging the check valve 131 connected to the supply port S, the molten resin flows in the forward direction from the plasticizing cylinder 121 to the injection cylinder 141 in the flow path PT1, and does not flow in the reverse direction from the injection cylinder 141 to the plasticizing cylinder 121. The flow path PT1 is a flow path through which the molten resin flows. The resin plasticized and melted by the plasticizing screw 122 is supplied to the inside 146 of the injection cylinder 141 through the check valve 131 and the supply port S of the injection cylinder 141. As a result, the inside 146 of the injection cylinder 141 can store the molten resin supplied from the plasticizing screw 122. Note that an opening and closing valve may be provided in the supply port S instead of the check valve 131.

[0020] A switching valve 143 is disposed in the interior 146 of the injection cylinder 141 near the nozzle N. The switching valve 143 is switchable between a position (open position) where the molten resin is injected from the nozzle N and a position (closed position) where the molten resin is blocked from being injected from the nozzle N. The switching valve 143 is a valve that prevents the molten resin from flowing out of the injection cylinder 141 from the nozzle N (injection port). The switching valve 143 is controlled by the control device 200. The injection cylinder 141 has an inner circumferential surface 147 that defines an internal space. The injection plunger 142 is disposed fitted in the injection cylinder 141 so as to be movable in the Z direction, which is the direction of the axis C1 relative to the injection cylinder 141.

[0021] The injection drive unit 144 includes a motor 151, which is an example of a drive source, a transmission mechanism 152, and a pressing member 153. The material of the pressing member 153 is preferably metal. The motor 151 is, for example, a rotary motor, and is controlled by the control device 200. The transmission mechanism 152 is a mechanism that transmits the driving force of the motor 151 to the pressing member 153. The transmission mechanism 152 includes, for example, a linear motion mechanism. The transmission mechanism 152 may further include a timing belt. The linear motion mechanism is a mechanism that converts rotational motion into linear motion, and is, for example, a mechanism that includes a ball screw and a nut. The linear motion mechanism has a linear motion member 154 that moves linearly in the Z direction. The pressing member 153 is connected to the linear motion member 154. As a result, in the first embodiment, the motor 151 can drive the pressing member 153 in the Z direction via the transmission mechanism 152 so that the pressing member 153 moves linearly in the Z direction. The pressing member 153 is configured as a separate body from the injection plunger 142, and is separated from the injection plunger 142. Therefore, the pressing member 153 is capable of coming into contact with and being separated from the injection plunger 142.

[0022] Here, among the Z directions, the direction in which each of the injection plunger 142 and the pressing member 153 approaches the nozzle N along the axis C1, that is, the direction in which the molten resin stored in the injection cylinder 141 is injected from the nozzle N of the injection cylinder 141 to the cavity CV, is defined as the Z1 direction. Also, among the Z directions, the direction in which each of the injection plunger 142 and the pressing member 153 moves away from the nozzle N along the axis C1 is defined as the Z2 direction. The Z2 direction is the opposite direction to the Z1 direction. Also, the movement of each of the injection plunger 142 and the pressing member 153 in the Z1 direction is referred to as forward movement, and the movement of each of the injection plunger 142 and the pressing member 153 in the Z2 direction is referred to as backward movement. The Z1 direction is an example of the first direction, and the Z2 direction is an example of the second direction. Each of the injection plunger 142 and the pressing member 153 can move in the Z1 direction and the Z2 direction.

[0023] The pressing member 153 is driven by the motor 151 to move in the Z direction, thereby being able to come into contact with and separate from the injection plunger 142. That is, the pressing member 153 is driven by the motor 151 to move in the Z1 direction, thereby being able to press the injection plunger 142 in the Z1 direction so as to move the injection plunger 142, which is in contact with the pressing member 153, in the Z1 direction. Also, the pressing member 153 is driven by the motor 151 to move in the Z2 direction, thereby being able to separate from the injection plunger 142. That is, the Z1 direction is the direction in which the pressing member 153 can press the injection plunger 142, and the Z2 direction is the direction in which the pressing member 153 can separate from the injection plunger 142.

[0024] The interior 146 of the injection cylinder 141 includes a portion 148 in which the injection plunger 142 is slidable in the Z direction, and a portion 149 located in the Z1 direction relative to the portion 148. Each of the portions 148 and 149 is a substantially cylindrical space. The portion 148 and the portion 149 are in communication with each other. The portion 148 has a larger diameter than the portion 149. That is, the injection plunger 142 is movable in the Z direction in the portion 148, but is restricted from moving in the Z1 direction by abutting against an abutment surface 150, which is a step portion between the portion 148 and the portion 149 in the injection cylinder 141. In this way, the injection plunger 142 is movable in the Z direction between the pressing member 153 and the abutment surface 150. The injection plunger 142 is restricted from moving in the Z2 direction beyond the pressing member 153 by abutting against the pressing member 153, and is restricted from moving in the Z1 direction beyond the abutment surface 150 by abutting against the abutment surface 150.

[0025] The supply port S and the nozzle N are in communication with a portion 149. In the portion 149, a switching valve 143 is disposed between the supply port S and the nozzle N. The switching valve 143 is an on-off valve. Therefore, when the switching valve 143 is switched to the closed position, the molten resin flowing from the plasticizing cylinder 121 through the flow path PT1 is supplied from the supply port S to the portion 149, and then from the portion 149 to the portion 148.

[0026] After the molten resin is supplied to the injection cylinder 141, with the switching valve 143 switched to the open position, the injection plunger 142 advances in the Z1 direction at a predetermined speed, thereby injecting the molten resin from the nozzle N. At this time, the check valve 131 reduces the backflow of the molten resin in the injection cylinder 141 into the plasticizing cylinder 121. The molten resin injected from the nozzle N is filled into the cavity CV that is connected to the nozzle N.

[0027] The pressing member 153 is a shaft-shaped member extending in the Z direction. The diameter of the pressing member 153 is, for example, 10 mm. The Z direction is also the longitudinal direction of the pressing member 153. The interior 146 of the injection cylinder 141 has an opening that is open at the rear end side in the Z1 direction. The pressing member 153 is inserted through the opening of the injection cylinder 141, so that a tip portion 1531 of the pressing member 153 in the Z1 direction is located in the interior 146 of the injection cylinder 141. The tip portion 1531 of the pressing member 153 in the Z1 direction is a first portion that faces the injection plunger 142. A rear end portion 1532 of the pressing member 153 in the Z1 direction is connected to the linear motion member 154.

[0028] The injection plunger 142 is a substantially cylindrical member. The injection plunger 142 includes a rear end portion 1422 in the Z1 direction that contacts the tip portion 1531 of the pressing member 153, and a tip portion 1421 in the Z1 direction that contacts the molten resin injected into the injection cylinder 141. The rear end portion 1422 is an example of a second portion that faces the pressing member 153. The rear end portion 1422 is a portion opposite to the tip portion 1421 in the Z direction. At least the tip portion 1421 of the injection plunger 142, in the first embodiment, the entire injection plunger 142 is located inside 146 of the injection cylinder 141.

[0029] It is preferable that at least one of the tip portion 1531 and the rear end portion 1422 is spherical. This allows the pressing member 153 and the injection plunger 142 to be in point contact. In the first embodiment, the tip portion 1531 is spherical, and the rear end portion 1422 is flat. Alternatively, the rear end portion 1422 may be spherical, and the tip portion 1531 may be flat. Alternatively, both the rear end portion 1422 and the tip portion 1531 may be spherical.

[0030] The injection plunger 142 is fitted (contacted) with the inner circumferential surface 147 in the interior 146 of the injection cylinder 141 so as to be slidable in the Z direction. The inner diameter φ1 of the injection cylinder 141 is larger than the diameter φ2 of the portion of the injection plunger 142 that fits with the injection cylinder 141. It is preferable that the difference (φ1-φ2) between the inner diameter φ1 of the injection cylinder 141 and the diameter φ2 of the injection plunger 142 is 2 μm or more and 50 μm or less. In the first embodiment, the inner diameter φ1 of the injection cylinder 141 is the diameter of the portion 148 of the interior 146. By making the difference (φ1-φ2) 2 μm or more and 50 μm or less, it is possible to effectively reduce the leakage of resin from the gap between the injection cylinder 141 and the injection plunger 142. In addition, it is possible to effectively reduce the occurrence of the injection plunger 142 getting caught on the inner circumferential surface 147 of the injection cylinder 141, that is, the occurrence of galling.

[0031] For example, if injection plunger 142 is a cylindrical member with a diameter φ2 of 12 mm and a height of 15 mm, and injection cylinder 141 has an inner diameter φ1 of 12.01 mm, the difference between inner diameter φ1 and diameter φ2 (φ1−φ2) is 0.01 mm.

[0032] On the other hand, the pressing member 153 is formed to have a smaller diameter than the injection plunger 142 so as not to come into contact with the inner circumferential surface 147 of the injection cylinder 141. In this manner, the pressing member 153 does not come into contact with the injection cylinder 141, i.e., is separated from the injection cylinder 141.

[0033] In the first embodiment, the manufacturing apparatus 100 further includes a sensor 155 used to detect whether the injection plunger 142 has come into contact with the pressing member 153 or whether the injection plunger 142 has separated from the pressing member 153. The sensor 155 is, for example, a strain gauge provided on the pressing member 153. By using the detection value of this sensor 155, the control device 200 can determine whether the injection plunger 142 has come into contact with the pressing member 153. Note that the sensor 155 may be any sensor that can detect the contact of the injection plunger 142 with the pressing member 153. That is, the sensor 155 may be a sensor that can detect the contact and / or separation between the injection plunger 142 and the pressing member 153. The contact and / or separation may also be abbreviated as contact and separation.

[0034] The sensor 155 is not limited to a mechanical sensor such as a strain gauge, but may be, for example, an electromagnetic sensor or an optical sensor.

[0035] The sensor 155 as an electromagnetic sensor can detect a change in capacitance or magnetic field according to the distance between the injection plunger 142 and the pressing member 153. When the sensor 155 is located near the injection cylinder 141, it is preferable to place a heat insulating member between the injection cylinder 141 and the sensor 155, considering the effect of heat from the injection cylinder 141 on the sensor 155 (reduction in accuracy). As a material for the heat insulating member, a material in which glass fiber is bound with an organic binder such as polyester or an inorganic binder such as a silicon compound can be used. In terms of heat resistance (for example, 200°C or higher), a material in which glass fiber is bound with a silicon compound binder is suitable for the heat insulating member. The sensor 155 as an electromagnetic sensor may be a sensor that detects the torque of a drive source for driving the pressing member 153. If the motor 151 is a servo motor, the sensor 155 may be a sensor that detects a servo motor current value as the distance between the injection plunger 142 and the pressing member 153.

[0036] Sensor 155 as an optical sensor may include a light emitting unit and a light receiving unit. Light is irradiated from the light emitting unit to the vicinity of the contact portion between ejection plunger 142 and pressing member 153. In a first example of detection of contact / separation between ejection plunger 142 and pressing member 153 by an optical sensor, the light emitting unit and the light receiving unit of sensor 155 may be disposed on the same side of the contact portion between ejection plunger 142 and pressing member 153. Of the light irradiated from the light emitting unit of sensor 155 to the vicinity of the contact portion between ejection plunger 142 and pressing member 153, the light receiving unit of sensor 155 receives reflected light from ejection plunger 142 and / or pressing member 153. When the ejection plunger 142 and the pressing member 153 are separated from each other, a gap is generated between the ejection plunger 142 and the pressing member 153, and at least a part of the irradiated light passes through the gap, is not reflected by either the ejection plunger 142 or the pressing member 153, and does not reach the light receiving section of the sensor 155. By utilizing this principle, if the amount of light received by the light receiving section of the sensor 155 is relatively large, it is possible to detect that the ejection plunger 142 and the pressing member 153 are in contact with each other. If the amount of light received by the light receiving section of the sensor 155 is relatively small, it is possible to detect that the ejection plunger 142 and the pressing member 153 are separated from each other. Here, the light reflected from the ejection plunger 142 and / or the pressing member 153 is described, but the reflector does not necessarily have to be the ejection plunger 142 and / or the pressing member 153 itself, and may be a reflecting member that is linked to the ejection plunger 142 and / or the pressing member 153.

[0037] In a second example of detecting the contact / separation between ejection plunger 142 and pressing member 153 by an optical sensor, a light emitting section and a light receiving section of sensor 155 can be disposed on opposite sides of the contact section between ejection plunger 142 and pressing member 153. Of the light irradiated from the light emitting section of sensor 155 to the vicinity of the contact section between ejection plunger 142 and pressing member 153, the light receiving section of sensor 155 receives the transmitted light that passes through the gap between ejection plunger 142 and pressing member 153. When ejection plunger 142 and pressing member 153 are separated from each other, a gap is generated between ejection plunger 142 and pressing member 153, and therefore at least a part of the irradiated light passes through this gap and reaches the light receiving section of sensor 155. When ejection plunger 142 and pressing member 153 are in contact with each other, there is no gap between ejection plunger 142 and pressing member 153, or the gap is small, so that at least a part of the irradiated light does not reach the light receiving portion of sensor 155. By utilizing this principle, if the amount of light received by the light receiving portion of sensor 155 is relatively large, it can be detected that ejection plunger 142 and pressing member 153 are separated from each other. If the amount of light received by the light receiving portion of sensor 155 is relatively small, it can be detected that ejection plunger 142 and pressing member 153 are in contact with each other.

[0038] In both the first and second examples of detecting the contact and separation between the injection plunger 142 and the pressing member 153 by the optical sensor, both the light emitting unit and the light receiving unit can be arranged so as to be linked to one of the injection plunger 142 and the pressing member 153. Alternatively, one of the light emitting unit and the light receiving unit can be arranged so as to be linked to one of the injection plunger 142 and the pressing member 153, and the other of the light emitting unit and the light receiving unit can be arranged so as to be linked to the other of the injection plunger 142 and the pressing member 153. Alternatively, one of the light emitting unit and the light receiving unit can be attached to a different structure that is not linked to either the injection plunger 142 or the pressing member 153. Natural light or illumination light in the installation environment of the manufacturing apparatus 100 can be used instead of the light emitting unit. On the other hand, if the light emitted by the sensor 155 is a modulated pulse type, the influence of disturbance light such as natural light or illumination light in the installation environment of the manufacturing apparatus 100 can be reduced, and stable detection can be achieved.

[0039] Considering the mounting space for sensor 155 and the effect (reduction in accuracy) of heat from injection cylinder 141 and injection plunger 142 on sensor 155, it is preferable to fix sensor 155, which integrates a light emitting section and a light receiving section, to pressing member 153. The light emitting section of optical sensor 155 fixed to pressing member 153 irradiates the end of injection plunger 142 on the pressing member 153 side, and the amount of light reflected by injection plunger 142 can be detected by the light receiving section of optical sensor 155.

[0040] By analyzing the output obtained from the sensor 155, it is possible to detect the contact and / or separation between the ejection plunger 142 and the pressing member 153 in a binary or multi-value manner. The binary detection of the contact and / or separation can be performed by comparing the output obtained from the sensor 155 with a predetermined threshold value. Furthermore, in the multi-value detection of the contact and / or separation, it is possible to obtain information such as the difference in the distance between the ejection plunger 142 and the pressing member 153 and the difference in the pressure between the ejection plunger 142 and the pressing member 153. Furthermore, by analyzing the output obtained from the sensor 155, it is possible to obtain various information. For example, the control device 200 can measure, in synchronization with the output from the sensor 155, the time from when the injection plunger 142 and the pressing member 153 are separated from each other until they come into contact with each other, and / or the time from when the injection plunger 142 and the pressing member 153 are in contact with each other until they are separated from each other. Then, the control device 200 can estimate information corresponding to the sliding resistance between the injection cylinder 141 and the injection plunger 142 based on the measured time. As a method for estimating information corresponding to the sliding resistance, calculation using an algorithm, LUT processing, machine learning model, etc. can be used, and these processes can be performed by the control device 200. In this way, the manufacturing apparatus 100 acquires information corresponding to the change in the sliding resistance between the injection cylinder 141 and the injection plunger 142 based on the change over time of the output from the sensor 155. If the sliding resistance changes, the back pressure during metering and the absolute pressure during the pressure holding process will change (the actual internal pressure will decrease), which may cause a change in the density of the resin in the molded product. The density of the resin in the molded product is related to the quality of the molded product. Therefore, by detecting the change in the sliding resistance using the sensor 155, it is possible to detect the change in the quality of the molded product. This makes it possible to ensure the quality of the molded product. The control device 200 can warn of the change in the quality of the molded product (inform the operator) before a large number of defective products are manufactured, thereby reducing the number of defective products. In this way, the sensor 155 can be used to reduce molding defects in molded products.

[0041] A method for manufacturing a molded product using the manufacturing apparatus 100 having the above configuration will be described in detail. FIGS. 2 to 5 are explanatory diagrams of a method for manufacturing a molded product using the manufacturing apparatus 100 according to the first embodiment. FIGS. 2 to 5 are schematic cross-sectional views of the manufacturing apparatus 100. In the first embodiment, the operation of the pressing member 153 is controlled by position and speed control rather than pressure control. In the manufacturing apparatus 100 according to the first embodiment, a metering step, an injection step, and a cooling step are repeated to sequentially manufacture a molded product. The manufacturing apparatus 100 according to the first embodiment can be used for molding an elastomer resin that does not require a pressure holding step. When molten resin is metered in the manufacturing apparatus 100, which is a pre-plunger type injection molding machine, the plasticizing screw 122 is rotated to rotate the plasticizing screw 122, and the plasticized molten resin is transported to the injection cylinder 141 and stored in the interior 146 of the injection cylinder 141.

[0042] 2 shows the state immediately before the start of the metering process of the manufacturing apparatus 100. At the completion of the injection process, that is, immediately before the start of the metering process, the control device 200 stops the rotation of the plasticizing screw 122. At that time, the injection plunger 142 stops at a cushion position P1 that is retreated in the Z2 direction by a predetermined amount (for example, 2 mm) from the cushion position P0. The cushion position P0 is the position where the injection plunger 142 contacts the abutment surface 150 in the interior 146 of the injection cylinder 141.

[0043] The ball 11 of the check valve 131 moves toward the plasticizing screw 122, and the flow path PT1 is closed in a state where the ball 11 is seated on the valve seat 51 as shown by the dashed circle in Fig. 2. In addition, the injection plunger 142 and the pressing member 153 are in contact with each other.

[0044] FIG. 3 shows the state of the manufacturing apparatus 100 during the metering process. The metering process is a process of metering the molten resin supplied from the plasticizing screw 122 to the injection cylinder 141. In the metering process, the control device 200 closes the switching valve 143 and operates the motor 151 to move the linear moving member 154 back in the Z2 direction, thereby moving the pressing member 153 back to the metering completion position P2. That is, in the metering process, the control device 200 controls the motor 151 to move the pressing member 153 to the metering completion position P2. The metering completion position P2 is an example of the first position. The metering completion position P2 is, for example, a position 25 mm away from the cushion position P0 in the Z2 direction. The injection plunger 142 remains at the cushion position P1 and is separated from the pressing member 153.

[0045] Thereafter, the control device 200 rotates the plasticizing screw 122 at, for example, 50 rpm to supply the molten resin plasticized by the plasticizing screw 122 to the injection cylinder 141 through the flow path PT1. At that time, the ball 11 of the check valve 131 moves toward the injection cylinder 141, and the ball 11 contacts the valve claw 52 as shown by the dashed circle in Fig. 3. In this contact state, a gap exists between the ball 11 and the valve claw 52, ​​and the flow path PT1 is opened. The injection plunger 142 is pushed by the pressure of the molten resin that has flowed into the interior 146 of the injection cylinder 141 through the supply port S, and retreats in the Z2 direction.

[0046] When molten resin is supplied to the injection cylinder 141 by the plasticizing screw 122 while the injection plunger 142 is separated from the pressing member 153, the injection plunger 142 is pressed in the Z2 direction by the molten resin and retreats in the Z2 direction until it comes into contact with the pressing member 153.

[0047] FIG. 4 shows the state of the manufacturing apparatus 100 at the completion of the metering process. The control device 200 determines that the metering of the molten resin is completed because the movement of the injection plunger 142 is restricted by the pressing member 153 located at the metering completion position P2. When the injection plunger 142 comes into contact with the pressing member 153, the movement in the Z2 direction is restricted. When the injection plunger 142 retreats in the Z2 direction and comes into contact with the pressing member 153, the detection value of the sensor 155 installed on the pressing member 153 changes beyond the threshold value. This causes the control device 200 to detect that the injection plunger 142 has come into contact with the pressing member 153. When the control device 200 detects that the injection plunger 142 has come into contact with the pressing member 153, it stops the rotation of the plasticizing screw 122. This completes the metering process. That is, the control device 200 determines that the metering of the molten resin is completed when the injection plunger 142 comes into contact with the pressing member 153 located at the metering completion position P2.

[0048] Here, if the injection plunger is forcibly retracted by the drive mechanism in the metering process, a phenomenon in which air is entrained in the molten resin in the injection cylinder may occur. There are several possible reasons why air is entrained in the molten resin. For example, air may be drawn into the injection cylinder from the gap between the injection plunger and the injection cylinder or from the plasticizing screw. In addition, for example, air dissolved in the molten resin may appear as air bubbles due to a change in the pressure of the molten resin. In any case, if a molded product is manufactured with air entrained in the molten resin, molding defects such as voids and silver streaks may occur in the molded product.

[0049] In the first embodiment, injection plunger 142 retracts due to the resin pressure in injection cylinder 141 in the metering process, so that air entrainment in the molten resin can be reduced compared to the case where the injection plunger is forcibly retracted.

[0050] FIG. 5 shows a state during the injection process of the manufacturing apparatus 100. In the injection process, the control device 200 opens the switching valve 143 and advances the pressing member 153 in the Z1 direction at a predetermined speed (for example, 20 mm / s). When the injection plunger 142 is pressed in the Z1 direction by the pressing member 153 advancing in the Z1 direction, the injection plunger 142 advances in the Z1 direction so as to inject the molten resin in the inside 146 of the injection cylinder 141 from the nozzle N of the injection cylinder 141 into the cavity CV. In this way, the injection plunger 142 advances while being pressed by the pressing member 153 in a state of contact with the pressing member 153, thereby injecting the molten resin in the injection cylinder 141 into the cavity CV of the mold 10. Then, the control device 200 stops the movement of the pressing member 153 when the injection plunger 142 reaches the cushion position P1.

[0051] During this injection process, the resin pressure inside 146 of injection cylinder 141 and in flow path PT1 increases, so that ball 11 of check valve 131 moves toward plasticizing screw 122 and flow path PT1 is closed. Closing flow path PT1 can reduce the backflow of resin into plasticizing screw 122.

[0052] Here, in the injection process, a large injection reaction force is applied to the pressing member 153. This force may cause the housing to which the transmission mechanism 152 is fixed to bend, causing the pressing member 153 to tilt slightly with respect to the axis C1.

[0053] In the first embodiment, even if the pressing member 153 is advanced in a slightly tilted state in the injection process, the outer circumferential surface of the pressing member 153 is kept out of contact with the inner circumferential surface 147 of the injection cylinder 141. That is, a clearance is provided between the pressing member 153 and the injection cylinder 141 so that the pressing member 153 and the injection cylinder 141 do not come into contact with each other.

[0054] In addition, because the tip portion 1531 of the pressing member 153 is spherical, even if the pressing member 153 advances with a slight inclination, the tip portion 1531 slides relative to the rear end portion 1422. This reduces the load on the mating portion between the injection plunger 142 and the injection cylinder 141, and reduces the occurrence of the injection plunger 142 getting caught on the injection cylinder 141, i.e., the occurrence of seizing.

[0055] In the injection process, the cavity CV of the mold 10 is filled with molten resin, and then in the cooling process, the resin in the mold 10 is cooled and solidified over a cooling time (e.g., 7 seconds). Thereafter, the mold 10 is opened, and the molded product is removed from the mold 10.

[0056] By the above process, the occurrence of molding defects such as voids and silver streaks in molded products can be reduced, and the yield rate of molded products is improved.

[0057] In the first embodiment, during the cooling time in the mold 10, the above-mentioned measuring step for producing the next molded product can be carried out.

[0058] [Second embodiment] A second embodiment will be described. In the second embodiment, the description of matters similar to those in the first embodiment will be simplified or omitted. FIGS. 6 to 9 are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus 100A according to the second embodiment. FIGS. 6 to 9 are schematic cross-sectional views of the manufacturing apparatus 100A. The configuration of the manufacturing apparatus 100A in the second embodiment is obtained by adding a pressure sensor 161 to the manufacturing apparatus 100 shown in FIG. 1 described in the first embodiment.

[0059] In the manufacturing apparatus 100A of the second embodiment, pressure control is used in controlling the operation of the pressing member 153. The pressure sensor 161 is a sensor for detecting the resin pressure inside the injection cylinder 141, and is provided inside the injection cylinder 141. A pressure value corresponding to the pressure sensed by the pressure sensor 161 is input to the control device 200 and processed. The control device 200 controls the motor 151 by issuing a control command to the motor 151 so that the pressure inside the injection cylinder 141 becomes a set pressure.

[0060] In the manufacturing apparatus 100A of the second embodiment, a measuring step, a suck back step, an injection step, a pressure holding step, and a cooling step are repeated to sequentially manufacture a molded product.

[0061] 6 shows the state of the manufacturing apparatus 100A immediately before the start of the metering process. The diameter of the plasticizing screw 122 is, for example, 32 mm. The outer diameter of the pressing member 153 is, for example, 18 mm. The injection plunger 142 is, for example, a cylindrical member having a diameter of 20 mm and a height of 25 mm, and the inner diameter of the injection cylinder 141 is, for example, 20.01 mm. At this time, the difference between the inner diameter of the injection cylinder 141 and the diameter of the injection plunger 142 is 0.01 mm, which is within the range of 2 μm to 50 μm.

[0062] At the completion of the injection process, that is, immediately before the start of the metering process, the control device 200 stops the rotation of the plasticizing screw 122. At that time, the injection plunger 142 stops at a cushion position P1, which is retreated in the Z2 direction by a predetermined amount (e.g., 3 mm) from the cushion position P0. The cushion position P0 is the position where the injection plunger 142 contacts the abutment surface 150 in the interior 146 of the injection cylinder 141.

[0063] The ball 11 of the check valve 131 moves to the side of the plasticizing screw 122, and the flow path PT1 is closed in a state in which the ball 11 is seated on the valve seat 51. In addition, the injection plunger 142 and the pressing member 153 are in contact with each other.

[0064] 7 shows the state of the manufacturing apparatus 100A during the metering process. In the metering process, the control device 200 closes the switching valve 143 and rotates the plasticizing screw 122 at, for example, 100 rpm to supply the molten resin plasticized by the plasticizing screw 122 to the injection cylinder 141 through the flow path PT1. At that time, the ball 11 of the check valve 131 moves to the injection cylinder 141 side, and the ball 11 contacts the valve claw 52. In this contact state, a gap exists between the ball 11 and the valve claw 52, ​​and the flow path PT1 is opened. The molten resin flows into the injection cylinder 141 through the check valve 131 and the supply port S. This increases the resin pressure in the injection cylinder 141.

[0065] In the metering process, a pressure called back pressure is applied to the injection plunger 142 by using the pressing member 153 against the molten resin flowing into the injection cylinder 141 by the rotation of the plasticizing screw 122. That is, the control device 200 operates the pressing member 153 in the Z2 direction so that the pressure inside the injection cylinder 141 is kept constant (for example, a back pressure of 1 MPa). Specifically, the control device 200 rotates the plasticizing screw 122, and moves the pressing member 153 backward in the Z2 direction while keeping the pressure of the molten resin constant in a state where the rear end portion 1422 of the injection plunger 142 and the front end portion 1531 of the pressing member 153 are in contact with each other.

[0066] Then, the control device 200 ends the metering process when the pressing member 153 reaches the metering completion position P2. Thus, in the metering process, the control device 200 controls the motor 151 to move the pressing member 153 to the metering completion position P2. The metering completion position P2 is an example of the first position, and is, for example, a position 60 mm away from the cushion position P0 in the Z2 direction. Thereafter, the process proceeds to the suck back process.

[0067] 8 shows the state of the manufacturing apparatus 100A during the suck back process. The suck back process is performed to reduce the resin pressure in the injection cylinder 141 after the measurement process, thereby reducing molding defects such as resin leakage from the nozzle N, i.e., dripping, and jetting that occurs in the next injection process.

[0068] In the suck back process, the control device 200 controls the motor 151 to move the pressing member 153 backward to a suck back completion position P3, which is backward in the Z2 direction from the metering completion position P2. The suck back completion position P3 is an example of the second position, and is, for example, a position 65 mm away from the cushion position P0 in the Z2 direction.

[0069] When the pressing member 153 is retracted, the injection plunger 142 and the pressing member 153 separate, and the pressing member 153 retracts first to the suck-back completion position P3. After that, the injection plunger 142 is pressed by the molten resin in the injection cylinder 141, retracts to the suck-back completion position P3, and contacts the pressing member 153 again. This causes the suck-back to occur, reducing nasal dripping and jetting.

[0070] In the second embodiment, in the suck back process, injection plunger 142 is not forcibly moved back by a drive mechanism or the like, but is moved back by the resin pressure of the molten resin. Therefore, injection plunger 142 moves back against the resin pressure in injection cylinder 141 in the suck back process, so no gap is generated between the molten resin and tip portion 1421 of injection plunger 142, and it is possible to reduce entrainment of air into the molten resin.

[0071] 9 shows the state of manufacturing apparatus 100A during the injection process. In the injection process, control device 200 opens switching valve 143 and moves pressing member 153 forward in the Z1 direction at a predetermined speed (e.g., 30 mm / s). Injection plunger 142 moves forward while being pressed by pressing member 153 in a state of contact with pressing member 153, and injects the molten resin in injection cylinder 141 into cavity CV of mold 10. Then, control device 200 stops the movement of pressing member 153 when injection plunger 142 reaches cushion position P1.

[0072] During this injection process, the resin pressure in the interior 146 of the injection cylinder 141 and in the flow path PT1 increases, so that the ball 11 of the check valve 131 moves toward the plasticizing screw 122 and the flow path PT1 is closed. Closing the flow path PT1 can reduce the backflow of resin into the plasticizing screw 122.

[0073] After filling the cavity CV of the mold 10 with resin in the injection process, the process moves to a pressure holding process. In the pressure holding process, the control device 200 controls the motor 151 so that the pressing member 153 presses the injection plunger 142 so that the pressure inside the injection cylinder 141 is kept constant (e.g., a pressure holding of 50 MPa), thereby compensating for contraction of the molded product in the cavity CV due to cooling. After completion of the pressure holding process, the molded product in the mold 10 is cooled for a cooling time (e.g., 10 s) in the cooling process. Thereafter, the mold 10 is opened, and the molded product is removed from the mold 10.

[0074] By the above process, the occurrence of molding defects such as voids and silver streaks in molded products can be reduced, and the yield rate of molded products is improved.

[0075] In the second embodiment, during the cooling time in the mold 10, the above-mentioned measuring step and suck back step for producing the next molded product can be carried out.

[0076] [Third embodiment] A third embodiment will be described. In the third embodiment, a case where the manufacturing apparatus is a family molding apparatus will be described. The family molding apparatus is an example of an injection molding apparatus, and has a mold capable of molding a plurality of molded products having different shapes. The mold is configured to define a plurality of cavities.

[0077] Figures 10 to 12 are explanatory diagrams of a method for manufacturing a molded product using a manufacturing apparatus 100B according to the third embodiment. Figures 10 to 12 are schematic cross-sectional views of the manufacturing apparatus 100B. Figure 10 shows a state in which the manufacturing apparatus 100B performs an injection process, which will be described later, Figure 11 shows a state in which the manufacturing apparatus 100B performs a pressure holding process, which will be described later, and Figure 12 shows a state in which the manufacturing apparatus 100B performs a measuring process, which will be described later.

[0078] The manufacturing apparatus 100B includes an injection molding machine 101B, a mold 112B, and a control device 200B. Inside the mold 112B, a cavity CV1 which is a first cavity and a cavity CV2 which is a second cavity are defined. The cavities CV1 and CV2 have different shapes or sizes. Different dwell pressures are applied to the cavities CV1 and CV2 in a dwell process.

[0079] The control device 200B is an example of a control unit, and is configured with, for example, one or more computers having a processor. The control device 200B is capable of controlling the entire manufacturing apparatus.

[0080] The injection molding machine 101B is, for example, an in-line screw type injection molding machine. The operation of the injection molding machine 101B is controlled by a control device 200B. The injection molding machine 101B includes a plasticizing section 111B and an injection section 123B. The molten resin supplied to the mold 112B by the injection molding machine 101B is filled into each of the cavities CV1 and CV2.

[0081] The plasticizing section 111B has a hopper (not shown), a plasticizing cylinder 121B, and a plasticizing screw 122B. For example, pellet-shaped resin material is fed into the hopper (not shown). The resin material is a thermoplastic resin, for example, polyphenylene ether (PPE). The plasticizing cylinder 121B is heated by a heater (not shown) to adjust the temperature to plasticize the supplied resin material. A plasticizing screw 122B is disposed in an interior 126B of the plasticizing cylinder 121B. The plasticizing screw 122B is a rotatable screw that can move forward and backward. The diameter of the plasticizing screw 122B is, for example, 36 mm.

[0082] The injection unit 123B has a motor (not shown) and is configured to rotate the plasticizing screw 122B and move the plasticizing screw 122B forward and backward. The injection unit 123B moves the plasticizing screw 122B forward, thereby injecting the molten resin into the mold 112B. The injection unit 123B is controlled by the control device 200B.

[0083] The manufacturing apparatus 100B has an injection cylinder 141B, an injection plunger 142B, a hot runner 143B, and an injection drive unit 144B. The operation of the injection drive unit 144B is controlled by a control device 200B. The injection cylinder 141B has a supply port S1 to which molten resin is supplied, and a gate G1 that injects the molten resin into the cavity CV1. The gate G1 is an example of an injection port. An interior 146B of the injection cylinder 141B and the cavity CV1 are connected via the gate G1. The material of the injection cylinder 141B and the injection plunger 142B is preferably metal.

[0084] The hot runner 143B is an injection cylinder. The plasticizing cylinder 121B is connected to a supply port of the molten resin in the hot runner 143B. The hot runner 143B has a gate G2 that injects the molten resin into the cavity CV2. The gate G2 is an example of an injection port. The inside of the hot runner 143B and the cavity CV2 are in communication with each other through the gate G2.

[0085] Furthermore, the manufacturing apparatus 100B has a valve pin V1 that opens and closes the gate G1, and a valve pin V2 that opens and closes the gate G2. The valve pin V1 is a valve for stopping the molten resin from flowing from the gate G1 to the outside of the injection cylinder 141B. The valve pin V2 is a valve for stopping the molten resin from flowing from the gate G2 to the outside of the hot runner 143B. The operations of the valve pins V1 and V2 are controlled by the control device 200B.

[0086] The hot runner 143B and the injection cylinder 141B are connected via a check valve 131B. The check valve 131B has the same configuration as the check valve 131 described in the first and second embodiments. The check valve 131B is connected to the supply port S1 in such a direction that the molten resin does not flow back from the injection cylinder 141B to the hot runner 143B. By arranging the check valve 131B in connection with the supply port S1, the molten resin flows in the forward direction from the hot runner 143B to the injection cylinder 141B, but does not flow in the reverse direction from the injection cylinder 141B to the hot runner 143B. The resin plasticized and melted by the plasticizing screw 122B is supplied to the inside 146B of the injection cylinder 141B via the hot runner 143B, the check valve 131B, and the supply port S1 of the injection cylinder 141B. This allows the molten resin supplied from the plasticizing screw 122B to be stored in the interior 146B of the injection cylinder 141B.

[0087] The injection cylinder 141B has an inner circumferential surface 147B that defines an internal space. The injection plunger 142B is fitted into the injection cylinder 141B and arranged to be movable in the Z direction, which is the direction of the axis C3, relative to the injection cylinder 141B.

[0088] The injection drive unit 144B includes a motor 151B, which is an example of a drive source, a transmission mechanism 152B, and a pressing member 153B. The material of the pressing member 153B is preferably metal. The motor 151B is, for example, a rotary motor, and is controlled by the control device 200B. The transmission mechanism 152B is a mechanism that transmits the driving force of the motor 151B to the pressing member 153B. The transmission mechanism 152B includes, for example, a linear motion mechanism. The transmission mechanism 152B may further include a timing belt. The linear motion mechanism is a mechanism that converts rotary motion into linear motion, and is, for example, a mechanism that includes a ball screw and a nut.

[0089] The linear motion mechanism has a linear motion member 154B that moves linearly in the Z direction. The pressing member 153B is connected to the linear motion member 154B. As a result, in the third embodiment, the motor 151B can drive the pressing member 153B in the Z direction via the transmission mechanism 152B so that the pressing member 153B moves linearly in the Z direction. The pressing member 153B is configured separately from the injection plunger 142B and is separated from the injection plunger 142B. Therefore, the pressing member 153B can come into contact with and be separated from the injection plunger 142B.

[0090] Here, the Z direction is the direction in which the injection plunger 142B and the pressing member 153B approach the gate G1 along the axis C3, that is, the direction in which the molten resin stored in the injection cylinder 141B is injected from the gate G1 to the cavity CV1, and is defined as the Z1 direction. The Z direction is the direction in which the injection plunger 142B and the pressing member 153B move away from the gate G1 along the axis C3. The Z2 direction is the opposite direction to the Z1 direction. The movement of the injection plunger 142B and the pressing member 153B in the Z1 direction is called forward movement, and the movement of the injection plunger 142B and the pressing member 153B in the Z2 direction is called backward movement. The Z1 direction is an example of the first direction, and the Z2 direction is an example of the second direction. The injection plunger 142B and the pressing member 153B can move in the Z1 direction and the Z2 direction.

[0091] The pressing member 153B is driven by the motor 151B to move in the Z direction, and can come into contact with and separate from the injection plunger 142B. That is, the pressing member 153B is driven by the motor 151B to move in the Z1 direction, and can press the injection plunger 142B in the Z1 direction so as to move the injection plunger 142B in contact with the pressing member 153B in the Z1 direction. Also, the pressing member 153B is driven by the motor 151B to move in the Z2 direction, and can separate from the injection plunger 142B. That is, the Z1 direction is the direction in which the pressing member 153B can press the injection plunger 142B, and the Z2 direction is the direction in which the pressing member 153B can separate from the injection plunger 142B.

[0092] An interior 146B of the injection cylinder 141B is a substantially cylindrical space in which the injection plunger 142B is slidable in the Z direction.

[0093] The pressing member 153B is a shaft-shaped member extending in the Z direction. The Z direction is also the longitudinal direction of the pressing member 153B. The interior 146B of the injection cylinder 141B has an opening with a rear end side in the Z1 direction open. The pressing member 153B is inserted through the opening of the injection cylinder 141B, so that the tip portion of the pressing member 153B in the Z1 direction is located in the interior 146B of the injection cylinder 141B. The tip portion of the pressing member 153B in the Z1 direction is a first portion facing the injection plunger 142B. The rear end portion of the pressing member 153B in the Z1 direction is connected to the linear motion member 154B.

[0094] The injection plunger 142B is a substantially cylindrical member. The diameter of the injection plunger 142B is, for example, 8 mm. The injection plunger 142B includes a rear end portion in the Z1 direction that contacts the tip portion of the pressing member 153B, and a front end portion in the Z1 direction that contacts the molten resin injected into the injection cylinder 141B. The rear end portion of the injection plunger 142B is an example of a second portion that faces the pressing member 153B. The rear end portion of the injection plunger 142B is a portion opposite to the tip portion of the injection plunger 142B in the Z direction. At least the tip portion of the injection plunger 142B, in the third embodiment, the entire injection plunger 142B is located inside 146B of the injection cylinder 141B.

[0095] It is preferable that at least one of the tip portion of the pressing member 153B and the rear end portion of the injection plunger 142B is spherical. This allows the pressing member 153B and the injection plunger 142B to be in point contact. In the third embodiment, the tip portion of the pressing member 153B is spherical, and the rear end portion of the injection plunger 142B is flat. The rear end portion of the injection plunger 142B may be spherical, and the tip portion of the pressing member 153B may be flat. Alternatively, both the rear end portion of the injection plunger 142B and the tip portion of the pressing member 153B may be spherical.

[0096] The injection plunger 142B is fitted (contacted) with the inner circumferential surface 147B in the interior 146B of the injection cylinder 141B so as to be slidable in the Z direction. The inner diameter of the injection cylinder 141B is larger than the diameter of the portion of the injection plunger 142B that fits with the injection cylinder 141B. It is preferable that the difference between the inner diameter of the injection cylinder 141B and the diameter of the portion of the injection plunger 142B that fits with the injection cylinder 141B is 2 μm or more and 50 μm or less. This can effectively reduce the leakage of resin from the gap between the injection cylinder 141B and the injection plunger 142B. In addition, it can effectively reduce the occurrence of the injection plunger 142B getting caught on the inner circumferential surface 147B of the injection cylinder 141B, i.e., the occurrence of galling.

[0097] On the other hand, the pressing member 153B is formed to have a smaller diameter than the injection plunger 142B so as not to come into contact with the inner circumferential surface 147B of the injection cylinder 141B. In this manner, the pressing member 153B is not in contact with the injection cylinder 141B, that is, is separated from the injection cylinder 141B.

[0098] A method for manufacturing a molded product using the manufacturing apparatus 100B having the above configuration will be described. FIG. 10 shows the state of the injection process of the manufacturing apparatus 100B. In the injection process, the control device 200B opens the gate G1 connected to the cavity CV1 while closing the gate G2 connected to the cavity CV2, and advances the plasticizing screw 122B of the injection molding machine 101B at a predetermined speed, for example, 50 mm / s. The molten resin injected from the injection molding machine 101B flows through a flow path in the hot runner 143B and passes through the check valve 131B. The molten resin that has passed through the check valve 131B passes through the gate G1 and is filled into the cavity CV1. The control device 200B opens the gate G2 at the timing when the unfilled volume of the cavity CV1 becomes a predetermined volume, for example, 30 cc. As a result, the molten resin also flows into the cavity CV2, and the molten resin can be simultaneously filled into two cavities CV1 and CV2 having different volumes. At this time, the tip portion of the pressing member 153B is held at the metering completion position P2, and the injection plunger 142B and the pressing member 153B are in contact with each other. The metering completion position P2 is an example of the first position. The metering completion position P2 is, for example, a position 20 mm away from the cushion position P0 in the Z2 direction.

[0099] 11 shows the state of the dwelling process of the manufacturing apparatus 100B. In the dwelling process, the control device 200B controls the injection drive unit 144B to apply a first dwelling pressure to the cavity CV1, and controls the injection molding machine 101B to apply a second dwelling pressure lower than the first dwelling pressure to the cavity CV2. In the dwelling process, the control device 200B applies a dwelling pressure of, for example, 80 MPa to the flow path of the injection cylinder 141B for, for example, 3 s by causing the pressing member 153B to press the injection plunger 142B. Meanwhile, the control device 200B applies a dwelling pressure of, for example, 50 MPa to the flow path of the hot runner 143B for, for example, 3 s by the plasticizing screw 122B of the injection molding machine 101B. During this dwelling process, the relationship between the pressure on the inlet side and the pressure on the outlet side of the resin of the check valve 131B is "outlet side pressure" > "inlet side pressure". Therefore, the check valve 131B is closed. Therefore, the dwelling pressure of 80 MPa applied by the injection plunger 142B is applied to the cavity CV1, and the dwelling pressure of 50 MPa applied by the plasticizing screw 122B of the injection molding machine 101B is applied to the cavity CV2. After the dwelling process is completed, the gates G1 and G2 are closed. When the dwelling process is completed, the injection plunger 142B is located at the cushion position P1. The cushion position P1 is, for example, 2 mm away from the cushion position P0 in the Z2 direction.

[0100] FIG. 12 shows the state of the metering process of the manufacturing apparatus 100B. In the metering process, the control device 200B operates the motor 151B to move the pressing member 153B backward to the metering completion position P2. At this time, the injection plunger 142B stays at or near the cushion position P1 and separates from the pressing member 153B. After that, the control device 200B rotates the plasticizing screw 122B of the injection molding machine 101B at, for example, 100 rpm to apply a back pressure of 2 MPa. As a result, the relationship between the pressure on the inflow side and the pressure on the outflow side of the resin of the check valve 131B becomes "pressure on the outflow side" < "pressure on the inflow side". Therefore, the check valve 131B is in an open state, and the molten resin plasticized and melted by the plasticizing screw 122B of the injection molding machine 101B flows into the inside of the injection cylinder 141B through the hot runner 143B. Then, the pressure of the molten resin flowing into the injection cylinder 141B presses the injection plunger 142B in the Z2 direction, and it retreats until it comes into contact with the pressing member 153B, which is stopped at the metering completion position P2. Meanwhile, the plasticizing screw 122B of the injection molding machine 101B continues to retreat while rotating until it has completed metering the amount of resin required for the next shot. After the injection molding machine 101B has completed metering, the molded products are removed from each of the cavities CV1 and CV2 after a cooling period. Then, the process moves to the injection process again.

[0101] In the third embodiment, injection plunger 142B is retracted by the resin pressure in injection cylinder 141B in the metering process, so that air entrainment in the molten resin can be reduced compared to the case where the injection plunger is forcibly retracted.

[0102] By the above process, the occurrence of molding defects such as voids and silver streaks in molded products can be reduced, and the yield rate of molded products is improved.

[0103] [Variations] In the above-mentioned first to third embodiments, the injection cylinder, the injection plunger and the pressing member can be modified in various ways.

[0104] (Variation 1) FIG. 13(a) is a schematic cross-sectional view of the injection cylinder 141C, the injection plunger 142C, and the pressing member 153C in the first modification. The material of the injection cylinder 141C, the injection plunger 142C, and the pressing member 153C is preferably metal. The material of the injection cylinder 141C is, for example, high-speed steel. The material of the injection plunger 142C is, for example, powdered high-speed steel. The material of the pressing member 153C is, for example, high-speed steel. As in the first to third embodiments, the direction in which the injection plunger 142C advances and retreats is the Z direction, the direction in which the injection plunger 142C advances is the Z1 direction, and the direction in which the injection plunger 142C retreats is the Z2 direction. The Z1 direction is the direction in which the molten resin is injected, and the Z2 direction is the direction opposite to the Z1 direction.

[0105] The injection plunger 142C has a front end portion 1421C in the Z1 direction and a rear end portion 1422C in the Z1 direction. The front end portion 1421C of the injection plunger 142C is located inside 146C of the injection cylinder 141C, and the rear end portion 1422C of the injection plunger 142C is located outside of the injection cylinder 141C.

[0106] An interior 146C of the injection cylinder 141C is a cylindrical space defined by an inner peripheral surface 147C of the injection cylinder 141C. The injection plunger 142C has a cylindrical shaft portion 41C inserted into the interior 146C and a flange portion 42C that can abut against an abutment surface 150C of the injection cylinder 141C. As a result, the shaft portion 41C of the injection plunger 142C fits into the inner peripheral surface 147C of the injection cylinder 141C.

[0107] In the first modification, the tip portion of the shaft portion 41C is the tip portion 1421C of the injection plunger 142C, and the rear end portion of the flange portion 42C is the rear end portion 1422C of the injection plunger 142C. Thus, the tip portion 1421C is included in the shaft portion 41C, and the rear end portion 1422C is included in the flange portion 42C.

[0108] The pressing member 153C has a tip portion 1531C in the Z1 direction. The tip portion 1531C of the pressing member 153C is capable of coming into contact with and being separated from the rear end portion 1422C of the injection plunger 142C, i.e., the rear end portion of the flange portion 42C. Because the flange portion 42C is located outside the injection cylinder 141C, the pressing member 153C capable of coming into contact with and being separated from the flange portion 42C is kept in a non-contact state with the injection cylinder 141C, i.e., kept separated from the injection cylinder 141C.

[0109] At least one of rear end portion 1422C of injection plunger 142C facing pressing member 153C and front end portion 1531C of injection plunger 142C facing pressing member 153C is preferably formed in a spherical shape. Here, front end portion 1531C is an example of the first portion, and rear end portion 1422C is an example of the second portion.

[0110] In the example of Fig. 13(a), the tip portion 1531C is formed in a spherical shape, and the rear end portion 1422C is formed in a flat shape. This allows the injection plunger 142C and the pressing member 153C to be in point contact. Note that the rear end portion 1422C may be spherical, and the tip portion 1531C may be flat. Alternatively, both the rear end portion 1422C and the tip portion 1531C may be spherical.

[0111] The inner diameter of the injection cylinder 141C is larger than the diameter of the shaft portion 41C of the injection plunger 142C. The difference between the inner diameter of the injection cylinder 141C and the diameter of the shaft portion 41C of the injection plunger 142C is preferably 2 μm or more and 50 μm or less. This effectively reduces the leakage of resin from the gap between the injection cylinder 141C and the shaft portion 41C of the injection plunger 142C. In addition, it effectively reduces the occurrence of the injection plunger 142C getting caught on the inner circumferential surface 147C of the injection cylinder 141C, i.e., the occurrence of galling.

[0112] In the first modification, since the rear end portion 1422C of the injection plunger 142C is exposed to the outside, the injection plunger 142C can be easily pulled out from the injection cylinder 141C during maintenance such as cleaning, improving maintainability.

[0113] In addition, because the rear end portion 1422C is included in the flange portion 42C, the injection plunger 142C can be easily pulled out from the injection cylinder 141C by hooking a tool on the flange portion 42C, further improving maintainability.

[0114] (Variation 2) 13(b) is a schematic cross-sectional view of injection cylinder 141D, injection plunger 142D, and pressing member 153D in Modification 2. The material of injection cylinder 141D, injection plunger 142D, and pressing member 153D is preferably metal. As in the first to third embodiments, the direction in which injection plunger 142D advances and retreats is the Z direction, the direction in which injection plunger 142D advances is the Z1 direction, and the direction in which injection plunger 142D retreats is the Z2 direction. The Z1 direction is the direction in which molten resin is injected, and the Z2 direction is the opposite direction to the Z1 direction.

[0115] The injection plunger 142D has a front end portion 1421D in the Z1 direction and a rear end portion 1422D in the Z1 direction. The front end portion 1421D of the injection plunger 142D is located inside 146D of the injection cylinder 141D, and the rear end portion 1422D of the injection plunger 142D is located outside the injection cylinder 141D.

[0116] The interior 146D of the injection cylinder 141D is a cylindrical space defined by an inner circumferential surface 147D of the injection cylinder 141D. The injection plunger 142D has a cylindrical shaft portion 41D inserted into the interior 146D, a cylindrical shaft portion 40D inserted into the interior 146D and having a larger diameter than the shaft portion 41D, and a flange portion 42D that can abut against an abutment surface 150D of the injection cylinder 141D. The shaft portion 40D is located in the Z1 direction relative to the shaft portion 41D. As a result, the shaft portion 40D of the injection plunger 142D fits into the inner circumferential surface 147D of the injection cylinder 141D.

[0117] In the second modification, the tip portion of shaft 40D is tip portion 1421D of injection plunger 142D, and the rear end portion of flange 42D is rear end portion 1422D of injection plunger 142D. Thus, tip portion 1421D is included in shaft 40D, and rear end portion 1422D is included in flange 42D.

[0118] The pressing member 153D has a tip portion 1531D in the Z1 direction. The tip portion 1531D of the pressing member 153D is capable of coming into contact with and being separated from the rear end portion 1422D of the injection plunger 142D, i.e., the rear end portion of the flange portion 42D. Because the flange portion 42D is located outside the injection cylinder 141D, the pressing member 153D that is capable of coming into contact with and being separated from the flange portion 42D is kept in a non-contact state with the injection cylinder 141D, i.e., kept separated from the injection cylinder 141D.

[0119] At least one of rear end portion 1422D of injection plunger 142D facing pressing member 153D and front end portion 1531D of injection plunger 142D facing pressing member 153D is preferably formed into a spherical shape. Here, front end portion 1531D is an example of the first portion, and rear end portion 1422D is an example of the second portion.

[0120] In the example of Fig. 13(b), the tip portion 1531D is formed in a spherical shape, and the rear end portion 1422D is formed in a flat shape. This allows the injection plunger 142D and the pressing member 153D to be in point contact. Note that the rear end portion 1422D may be spherical, and the tip portion 1531D may be flat. Alternatively, both the rear end portion 1422D and the tip portion 1531D may be spherical.

[0121] The inner diameter of the injection cylinder 141D is larger than the diameter of the shaft portion 40D of the injection plunger 142D. The difference between the inner diameter of the injection cylinder 141D and the diameter of the shaft portion 40D of the injection plunger 142D is preferably 2 μm or more and 50 μm or less. This effectively reduces the leakage of resin from the gap between the injection cylinder 141D and the shaft portion 40D of the injection plunger 142D. In addition, it effectively reduces the occurrence of the injection plunger 142D getting caught on the inner circumferential surface 147D of the injection cylinder 141D, i.e., the occurrence of galling.

[0122] In the second modification, since the rear end portion 1422D of the injection plunger 142D is exposed to the outside, the injection plunger 142D can be easily pulled out from the injection cylinder 141D during maintenance such as cleaning, improving maintainability.

[0123] In addition, because rear end portion 1422D is included in flange portion 42D, injection plunger 142D can be easily pulled out from injection cylinder 141D by hooking a tool on flange portion 42D, further improving maintainability.

[0124] The contact area of ​​the injection plunger 142D of the modification 2 with the inner circumferential surface 147D is smaller than that of the modification 1. Therefore, it is possible to effectively reduce the injection plunger 142D from getting caught on the inner circumferential surface 147D of the injection cylinder 141D more effectively than in the modification 1.

[0125] [Fourth embodiment] 13(c) is a schematic cross-sectional view of injection cylinder 141E, injection plunger 142E, and pressing member 153E of the manufacturing apparatus according to the fourth embodiment. The material of injection cylinder 141E, injection plunger 142E, and pressing member 153E is preferably metal. As in the first to third embodiments, the direction in which injection plunger 142E advances and retreats is the Z direction, the direction in which injection plunger 142E advances is the Z1 direction, and the direction in which injection plunger 142E retreats is the Z2 direction. The Z1 direction is the direction in which molten resin is injected, and the Z2 direction is the direction opposite to the Z1 direction.

[0126] The injection plunger 142E has a front end portion 1421E in the Z1 direction and a rear end portion 1422E in the Z1 direction. The front end portion 1421E of the injection plunger 142E is located inside 146E of the injection cylinder 141E, and the rear end portion 1422E of the injection plunger 142E is located outside of the injection cylinder 141E.

[0127] The injection cylinder 141E has a base body 61E and a sleeve 62E. The sleeve 62E is detachably attached to the base body 61E. The injection plunger 142E is fitted into the sleeve 62E.

[0128] The sleeve 62E has an inner circumferential surface 148E that defines a cylindrical opening. The opening of the sleeve 62E is in communication with the interior of the base body 61E. The interior of the base body 61E is also formed in a cylindrical shape. The diameter of the opening of the sleeve 62E is smaller than the diameter of the interior of the base body 61E. The opening of the sleeve 62E and the interior of the base body 61E constitute an interior 146E of the injection cylinder 141E. The interior 146E of the injection cylinder 141E is a space defined by an inner circumferential surface 147E of the injection cylinder 141E.

[0129] The injection plunger 142E has a cylindrical shaft portion 41E inserted into the interior 146E and a flange portion 42E that can abut against an abutment surface 150E of the injection cylinder 141E. The abutment surface 150E is included in the sleeve 62E. In the fourth embodiment, the shaft portion 41E of the injection plunger 142E is inserted into an opening of the sleeve 62E and engages with an inner circumferential surface 148E of the sleeve 62E. The engagement length in the Z direction of the engagement portion between the injection plunger 142E and the sleeve 62E is, for example, 35 mm.

[0130] In the fourth embodiment, the tip portion of the shaft portion 41E is the tip portion 1421E of the injection plunger 142E, and the rear end portion of the flange portion 42E is the rear end portion 1422E of the injection plunger 142E. Thus, the tip portion 1421E is included in the shaft portion 41E, and the rear end portion 1422E is included in the flange portion 42E.

[0131] The pressing member 153E has a tip portion 1531E in the Z1 direction. The tip portion 1531E of the pressing member 153E can come into contact with and separate from the rear end portion 1422E of the injection plunger 142E, i.e., the rear end portion of the flange portion 42E. Because the flange portion 42E is located outside the injection cylinder 141E, the pressing member 153E that can come into contact with and separate from the flange portion 42E is kept in a non-contact state with the injection cylinder 141E, i.e., kept apart from the injection cylinder 141E.

[0132] At least one of rear end portion 1422E of injection plunger 142E facing pressing member 153E and front end portion 1531E of pressing member 153E facing injection plunger 142E is preferably formed in a spherical shape. Here, front end portion 1531E is an example of the first portion, and rear end portion 1422E is an example of the second portion.

[0133] In the example of Fig. 13(c), the tip portion 1531E is formed in a spherical shape, and the rear end portion 1422E is formed in a flat shape. This allows the injection plunger 142E and the pressing member 153E to be in point contact. Note that the rear end portion 1422E may be spherical, and the tip portion 1531E may be flat. Alternatively, both the rear end portion 1422E and the tip portion 1531E may be spherical.

[0134] The inner diameter of the sleeve 62E of the injection cylinder 141E is larger than the diameter of the shaft portion 41E of the injection plunger 142E. The difference between the inner diameter of the sleeve 62E of the injection cylinder 141E and the diameter of the shaft portion 41E of the injection plunger 142E is preferably 2 μm or more and 50 μm or less. This effectively reduces the leakage of resin from the gap between the sleeve 62E of the injection cylinder 141E and the shaft portion 41E of the injection plunger 142E. In addition, it effectively reduces the occurrence of the injection plunger 142E getting caught on the inner circumferential surface 148E of the sleeve 62E of the injection cylinder 141E, i.e., the occurrence of galling.

[0135] In the fourth embodiment, since the rear end portion 1422E of the injection plunger 142E is exposed to the outside, the injection plunger 142E can be easily pulled out from the injection cylinder 141E during maintenance such as cleaning, improving maintainability.

[0136] In addition, because rear end portion 1422E is included in flange portion 42E, injection plunger 142E can be easily pulled out from injection cylinder 141E by hooking a tool on flange portion 42E, further improving maintainability.

[0137] The injection plunger 142E is configured not to come into contact with the base body 61E of the injection cylinder 141E. Therefore, the contact area of ​​the injection plunger 142E with the inner circumferential surface 147E is smaller than that of the first modification. That is, the injection plunger 142E comes into contact with only the inner circumferential surface 148E of the sleeve 62E of the inner circumferential surface 147E. Therefore, according to the fourth embodiment, it is possible to effectively reduce the occurrence of the injection plunger 142E getting caught on the inner circumferential surface 147E of the injection cylinder 141E, that is, the occurrence of galling, more effectively than in the first modification.

[0138] Furthermore, by using a detachable sleeve 62E on the base 61E, even if wear or the like occurs in the fitting portion between the injection cylinder 141E and the injection plunger 142E due to long-term use, it can be dealt with by replacing only the sleeve 62E, further improving maintainability.

[0139] Here, injection plunger 142E includes a portion that slides relative to injection cylinder 141E. Resin adhering to the portion that slides relative to injection cylinder 141E may leak out of injection cylinder 141E and accumulate outside injection cylinder 141E.

[0140] FIG. 14 is an explanatory diagram of a part of the manufacturing apparatus according to the fourth embodiment. FIG. 14 shows a cross section of a part of the manufacturing apparatus according to the fourth embodiment. In FIG. 14, a seal member 63 such as an O-ring seals between the sleeve 62E and the base 61E. In FIG. 14, the sleeve 62E is fixed (fastened) to the base 61E of the injection cylinder 141E with a screw 64. The screw 64 presses the sleeve 62E against the base 61E of the injection cylinder 141E. In the area where the injection plunger 142E and the sleeve 62E slide with each other due to the movement of the injection plunger 142E, the area of ​​the part of the injection plunger 142E that slides against the sleeve 62E is preferably larger than the area of ​​the part of the sleeve 62E that slides against the injection plunger 142E.

[0141] The shaft portion 41E of the injection plunger 142E includes a portion that fits and slides in the injection cylinder 141E. The diameter of the shaft portion 41E of the injection plunger 142E is L1. The inner diameter of the sleeve 62E is L2. The inner diameter of the base 61E is L3. The fitting length in the Z direction of the fitting portion between the injection plunger 142E and the sleeve 62E is L4.

[0142] The amount of resin leakage M can be calculated from the following formula (1).

number

[0143] In formula (1), b is the diameter, i.e., the width of the gap, l is the length of the gap, h is the height of the gap, η is the viscosity of the fluid, and P1-P2 is the pressure difference. From formula (1), we can see that the larger l is or the smaller b is, the more the amount of resin leakage M can be reduced.

[0144] Here, l corresponds to the fitting length L4, and b corresponds to the diameter L1 of the shaft portion 41E. That is, in order to reduce the amount of resin leakage M, the longer the fitting length L4, the better, and / or the smaller the diameter L1 of the shaft portion 41E, the better.

[0145] Therefore, it is preferable that the fitting length L4 is longer than the diameter L1. Experimental results show that the fitting length L4 is preferably 103% or more of the diameter L1 of the shaft portion 41E. On the other hand, if the fitting length L4 is extremely large, the sliding properties decrease, so it is preferable that the fitting length L4 is 270% or less of the diameter L1 of the shaft portion 41E. For example, it is preferable that the diameter L1 is 5 mm to 12.5 mm, and the fitting length L4 is 12.5 mm to 20 mm.

[0146] The diameter L1 of the shaft portion 41E is smaller than the inner diameter L2 of the sleeve 62E. The difference between the diameter L1 of the shaft portion 41E and the inner diameter L2 of the sleeve 62E is preferably 0.001 mm to 0.010 mm.

[0147] The inner diameter L2 of the sleeve 62E may be the same as the inner diameter L3 of the base 61E of the injection cylinder 141E, but it is preferable that the inner diameter L2 of the sleeve 62E is smaller than the inner diameter L3 of the base 61E. Experimental results show that the inner diameter L2 of the sleeve 62E is preferably 99.0% or more and less than 100.0% of the inner diameter L3 of the base 61E, more preferably 99.5% or more, and more preferably 99.8% or less. For example, it is preferable that the inner diameter L2 of the sleeve 62E is 0.01 mm to 0.1 mm smaller than the inner diameter L3 of the base 61E.

[0148] If the gap between the base 61E of the injection cylinder 141E and the injection plunger 142E is large, the resin present in the gap may leak out of the injection cylinder. Therefore, in the fourth embodiment, the inner diameter L3 of the base 61E is made as close as possible to the inner diameter L2 of the sleeve 62E to make the gap between the base 61E and the injection plunger 142E as small as possible, thereby reducing the resin leakage.

[0149] 15(a) and 15(b) are explanatory views of a part of a manufacturing apparatus according to a fourth embodiment. In FIG. 15(a) and FIG. 15(b), a cross section of a part of a manufacturing apparatus according to a fourth embodiment is shown. In FIG. 15(a) and FIG. 15(b), a chamfered portion 42 is formed at the tip of an injection plunger 142E. The chamfered portion 42 can be, for example, a C-chamfered portion. The chamfering is performed at a distance of about 0.1 mm to 1.0 mm, preferably 0.2 mm to 0.6 mm, from the corner before chamfering. The width of the chamfered portion 42 is about 0.15 mm to 1.5 mm.

[0150] 15(b), a chamfered portion 43 is further formed on the inner side of the sleeve 62E, on the side of the base 61E. The chamfered portion 43 forms a step L5 corresponding to the depth of the chamfered portion 43 on the surface formed by the inner wall of the sleeve 62E and the inner wall of the base 61E, i.e., the surface facing the side surface of the shaft portion 41E.

[0151] If there is a step between the sleeve 62E and the base 61E, resin is likely to accumulate at the step, and the resin accumulated at the step is likely to increase in viscosity. The highly viscous resin accumulated at the step may adhere to the injection plunger and cause resin leakage. Therefore, it is preferable that the step between the sleeve 62E and the base 61E is as small as possible. A step of about (L3 - L2) / 2 can be formed between the sleeve 62E and the base 61E. The step formed between the sleeve 62E and the base 61E is preferably smaller than the difference between the inner diameter L3 of the base 61E and the diameter L1 of the injection plunger 142E, that is, L3 - L1. More preferably, the step formed between the sleeve 62E and the base 61E is (L3 - L1) / 2 or less. For example, if a chamfered portion (for example, the chamfered portion 43 of the sleeve 62E) is provided on the sleeve 62E and / or the base 61E, the step L5 formed between the sleeve 62E and the base 61E may exceed L3 - L1. L3 - L1 is, for example, 0.01 mm to 0.1 mm. The step L5 formed by a chamfered portion 43 similar to the chamfered portion 42 of the injection plunger 142E can be 0.1 mm to 1.0 mm. If a chamfered portion is provided on the sleeve 62E or the base 61E to a depth of about 0.1 mm to 1.0 mm, the step L5 formed between the sleeve 62E and the base 61E will be about 0.1 mm to 1.0 mm, exceeding L3 - L1 which is about 0.01 mm to 0.1 mm. Therefore, as shown in Fig. 15(b), it is preferable not to provide a chamfered portion of about 0.1 mm to 1.0 mm on the base 61E side of the sleeve 62E or on the sleeve 62E side of the base 61E. As shown in Fig. 15(a) rather than Fig. 15(b), it is preferable to minimize the step between the sleeve 62E and the base 61E, for example, making the step L5 smaller than L3 - L1 (L5 < L3 - L1), and more preferably making the step L5 half or less of L3 - L1 (L5 ≤ (L3 - L1) / 2).

[0152] The surface of the injection plunger 142E is preferably provided with a crystal layer containing crystals with a crystal grain size of 10 nm to 1 μm, preferably 50 nm to 500 nm, more preferably 100 nm to 300 nm. The crystal grain size of polycrystalline metal materials is often several μm to several tens of μm, but by forming a crystal layer (nanocrystalline layer, microcrystalline layer) composed of nanocrystals (microcrystals) with a crystal grain size of 1 μm or less near the surface, wear resistance, fatigue strength, and sliding properties are improved. Such surface treatment can be performed using shot peening. Shot peening is a type of cold processing method in which a workpiece is subjected to high-speed collision with countless spherical particles called abrasives or media. Shot peening causes uneven plastic deformation due to the spherical particles colliding with the workpiece, and can also achieve surface modification such as suppressing crack growth due to compressive residual stress and improving wear resistance due to increased surface hardness. Note that a similar crystal layer can also be applied to the injection plungers of other embodiments.

[0153] [Fifth embodiment] A fifth embodiment will be described. In the fifth embodiment, the description of the same matters as in the first embodiment will be simplified or omitted. Fig. 16 is a schematic cross-sectional view of a manufacturing apparatus 100F according to the fifth embodiment.

[0154] In the manufacturing apparatus 100 of the first embodiment described above, the case where the injection plunger 142 is separated from the injection drive unit 144, that is, the case where the injection plunger 142 is capable of approaching and retracting from the pressing member 153 has been described. In the manufacturing apparatus 100F of the fifth embodiment, the pressing member 153 and the injection plunger 142 in the manufacturing apparatus 100 of the first embodiment are replaced with the injection plunger 142F. That is, the injection plunger 142F is connected to the linear motion member 154 of the injection drive unit 144. In the manufacturing apparatus 100F, the other configurations are the same as those of the manufacturing apparatus 100 of the first embodiment. The injection plunger 142F can be driven in the Z direction by the motor 151. The control device 200 can control the motor 151. That is, the control device 200 can control the drive of the motor 151 so that the injection plunger 142F moves in the Z direction.

[0155] When supplying molten resin to the injection cylinder 141, the control device 200 stops driving the motor 151 so that the injection plunger 142F can move in the Z2 direction. For example, when performing position and speed control as in the first embodiment, the driving of the motor 151 can be stopped in the metering process. As a result, the driving force of the motor 151 is no longer generated, and the injection plunger 142F can move in the Z2 direction by the pressing force of the molten resin. Then, when injecting the molten resin from the injection cylinder 141, the control device 200 drives the motor 151 so that the injection plunger 142F can move in the Z1 direction.

[0156] As another example, the control device 200 may stop driving the motor 151 so that the injection plunger 142F can move in the Z2 direction when the supply of the molten resin to the injection cylinder 141 is completed. For example, when performing pressure control as in the second embodiment, the driving of the motor 151 may be stopped in the suck back process. As a result, the driving force of the motor 151 is no longer generated, and the injection plunger 142F can move in the Z2 direction by the pressing force of the molten resin.

[0157] As described above, in the fifth embodiment as well, the occurrence of molding defects such as voids and silver streaks in molded products can be reduced, and the yield rate of manufacturing molded products is improved.

[0158] The configuration and control operation of the fifth embodiment can also be applied to the third embodiment described above.

[0159] The present disclosure is not limited to the above-described embodiments, and many modifications of the present embodiments are possible within the technical concept of the present disclosure. Furthermore, the effects described in the embodiments are merely a list of the most preferable effects resulting from the embodiments of the present disclosure, and the effects of the embodiments of the present disclosure are not limited to those described in the embodiments.

[0160] The disclosure of this specification includes not only what is explicitly described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto. The disclosure of this specification also includes the complement of each individual concept described in this specification. In other words, if this specification contains a statement that "A is B," for example, this specification can be said to disclose that "A is not B," even if the statement that "A is not B" is omitted. This is because when a statement that "A is B" is made, it is assumed that the case in which "A is not B" is taken into consideration.

[0161] The disclosure of the above embodiments includes the following sections.

[0162] (Section 1) an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger that is fitted to the injection cylinder and arranged to be movable in a first direction and a second direction opposite to the first direction; the injection cylinder has a base body that stores the molten resin therein and a sleeve that is detachable from the base body, The injection plunger is inserted into the base through an opening provided in the sleeve and slides along the sleeve. A manufacturing apparatus comprising:

[0163] (Section 2) the injection plunger is spaced from the base; 2. The manufacturing apparatus according to item 1,

[0164] (Section 3) a pressing member that is movable away from the injection plunger and that is capable of pressing the injection plunger so as to move the injection plunger in the first direction; 3. The manufacturing apparatus according to item 1 or 2,

[0165] (Section 4) an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger that is fitted to the injection cylinder and arranged to be movable in a first direction and a second direction opposite to the first direction; a pressing member that is movable away from the injection plunger and that is capable of pressing the injection plunger so as to move the injection plunger in the first direction; and a sensor capable of detecting contact and / or separation between the injection plunger and the pressing member. A manufacturing apparatus comprising:

[0166] (Section 5) The injection plunger is moved in the second direction by the molten resin supplied to the injection cylinder pressing the injection plunger while the pressing member is separated from the injection plunger. 5. The manufacturing apparatus according to item 3 or 4.

[0167] (Section 6) an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger that is fitted to the injection cylinder and arranged to be movable in a first direction and a second direction opposite to the first direction; a pressing member that is movable away from the injection plunger and that is capable of pressing the injection plunger so as to move the injection plunger in the first direction; a drive source capable of driving the pressing member in the first direction and the second direction; A control unit capable of controlling the driving source, The injection plunger is moved in the second direction by the molten resin supplied to the injection cylinder pressing the injection plunger while the pressing member is separated from the injection plunger, The control unit is controlling the driving source to move the pressing member to a first position when metering the molten resin to be supplied to the injection cylinder; controlling the driving source so as to perform injection after retracting the pressing member to a second position retracted in the second direction from the first position; A manufacturing apparatus comprising:

[0168] (Section 7) At least a tip portion of the injection plunger is located inside the injection cylinder. 7. The manufacturing apparatus according to any one of items 1 to 6,

[0169] (Section 8) The entire injection plunger is located within the injection cylinder. 8. The manufacturing apparatus according to any one of items 1 to 7.

[0170] (Section 9) A rear end portion of the injection plunger is located outside the injection cylinder. 8. The manufacturing apparatus according to any one of items 1 to 7.

[0171] (Section 10) the injection cylinder has a base body that stores the molten resin therein and a sleeve that is detachable from the base body, The injection plunger is inserted into the base through an opening provided in the sleeve and fitted into the sleeve. 7. The manufacturing apparatus according to any one of items 4 to 6,

[0172] (Section 11) an area of ​​a portion of the injection plunger that slides against the sleeve is larger than an area of ​​a portion of the sleeve that slides against the injection plunger; 11. The manufacturing apparatus according to any one of items 1 to 3 and 10.

[0173] (Section 12) A fitting length of a fitting portion between the sleeve and the injection plunger is greater than a diameter of the injection plunger. 12. The manufacturing apparatus according to any one of items 1 to 3, 10 and 11,

[0174] (Section 13) The length of the engagement between the sleeve and the injection plunger is 103% or more and 270% or less of the diameter of the injection plunger. 13. The manufacturing apparatus according to any one of items 1 to 3 and 10 to 12.

[0175] (Section 14) The inner diameter of the sleeve is smaller than the inner diameter of the base body. 14. The manufacturing apparatus according to any one of items 1 to 3 and 10 to 13.

[0176] (Section 15) The inner diameter of the sleeve satisfies at least one of the following: the inner diameter of the sleeve is 99.0% or more and less than 100.0% of the inner diameter of the base; and the inner diameter of the sleeve is 0.01 mm to 0.1 mm smaller than the inner diameter of the base. 15. The manufacturing apparatus according to any one of items 1 to 3 and 10 to 14.

[0177] (Section 16) a step between the sleeve and the base is smaller than a difference between a diameter of the injection plunger and an inner diameter of the base; 16. The manufacturing apparatus according to any one of items 1 to 3 and 10 to 15.

[0178] (Section 17) The pressing member is spaced from the injection cylinder. 7. The manufacturing apparatus according to any one of items 3 to 6,

[0179] (Section 18) At least one of a first portion of the pressing member facing the injection plunger and a second portion of the injection plunger facing the pressing member is formed in a spherical shape. 7. The manufacturing apparatus according to any one of items 3 to 6,

[0180] (Section 19) The difference between the inner diameter of the injection cylinder and the diameter of the part of the injection plunger that fits with the injection cylinder is 2 μm or more and 50 μm or less. 19. The manufacturing apparatus according to any one of items 1 to 18,

[0181] (Section 20) the injection cylinder has a supply port through which the molten resin is supplied, The injection cylinder further includes a valve that prevents the molten resin from flowing out of the injection cylinder from the supply port. 20. The manufacturing apparatus according to any one of items 1 to 19,

[0182] (Section 21) the injection cylinder has an injection port through which the molten resin is injected, Further, a valve is provided to prevent the molten resin from flowing out of the injection cylinder from the injection port. 21. The manufacturing apparatus according to any one of items 1 to 20,

[0183] (Section 22) A mold defining a cavity, the molten resin being injected into the cavity. 22. The manufacturing apparatus according to any one of items 1 to 21,

[0184] (Section 23) A mold is provided that defines a plurality of cavities, and the molten resin is injected into the plurality of cavities. 22. The manufacturing apparatus according to any one of items 1 to 21,

[0185] (Section 24) a drive source capable of driving the pressing member in the first direction and the second direction; A control unit capable of controlling the driving source is further provided. 6. The manufacturing apparatus according to any one of items 3 to 5,

[0186] (Section 25) The control unit is controlling the driving source to move the pressing member to a first position when metering the molten resin to be supplied to the injection cylinder; 25. The manufacturing apparatus according to item 24,

[0187] (Section 26) the control unit determines that the metering of the molten resin is completed when the movement of the injection plunger is restricted by the pressing member located at the first position. 26. The manufacturing apparatus according to item 25,

[0188] (Section 27) Further comprising a sensor for detecting whether the injection plunger has contacted the pressing member or whether the injection plunger has separated from the pressing member. 7. The manufacturing apparatus according to item 3 or 6, (Section 28) The sensor is an optical sensor. 5. The manufacturing apparatus according to item 4,

[0189] (Section 29) acquiring information corresponding to a change in sliding resistance between the injection cylinder and the injection plunger based on a change over time in an output from the sensor; 5. The manufacturing apparatus according to item 4,

[0190] (Section 30) the control unit controls the drive source to move the pressing member backward to a second position that is backward in the second direction from the first position. 26. The manufacturing apparatus according to item 25,

[0191] (Section 31) an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger that is fitted to the injection cylinder and arranged to be movable in a first direction and a second direction opposite to the first direction; A drive source that drives the injection plunger; A control unit that controls the drive source, the control unit drives the drive source so that the injection plunger is movable in the first direction when the molten resin is injected from the injection cylinder; the control unit stops driving the drive source so that the injection plunger is movable in the second direction when the molten resin is supplied to the injection cylinder or when the supply of the molten resin to the injection cylinder is completed. A manufacturing apparatus comprising:

[0192] (Section 32) Item 32. A method for producing a molded product, comprising producing a molded product by the manufacturing apparatus according to any one of items 1 to 31. [Explanation of symbols]

[0193] 100... manufacturing apparatus, 141... injection cylinder, 142... injection plunger

Claims

1. an injection cylinder to which molten resin is supplied and which injects the molten resin; an injection plunger fitted to the injection cylinder so as to be movable in a first direction and a second direction opposite to the first direction; a pressing member that is movable away from the injection plunger and that is capable of pressing the injection plunger so as to move the injection plunger in the first direction; a drive source capable of driving the pressing member in the first direction and the second direction; a control unit capable of controlling the drive source, the injection plunger is moved in the second direction by the molten resin supplied to the injection cylinder pressing the injection plunger while the pressing member is separated from the injection plunger, The control unit controlling the drive source to move the pressing member to a first position when metering the molten resin to be supplied to the injection cylinder; controlling the drive source so as to perform injection after the pressing member is retracted to a second position retracted in the second direction from the first position; A manufacturing apparatus characterized by:

2. At least a tip portion of the injection plunger is located inside the injection cylinder. The manufacturing apparatus according to claim 1 .

3. The injection plunger is entirely located inside the injection cylinder. The manufacturing apparatus according to claim 1 .

4. a rear end portion of the injection plunger located outside the injection cylinder; The manufacturing apparatus according to claim 1 .

5. The pressing member is spaced apart from the injection cylinder. The manufacturing apparatus according to claim 1 .

6. At least one of a first portion of the pressing member facing the injection plunger and a second portion of the injection plunger facing the pressing member is formed in a spherical shape. The manufacturing apparatus according to claim 1 .

7. a difference between an inner diameter of the injection cylinder and a diameter of a portion of the injection plunger that fits with the injection cylinder being 2 μm or more and 50 μm or less; The manufacturing apparatus according to claim 1 .

8. the injection cylinder has a supply port through which the molten resin is supplied, The injection cylinder further includes a valve that prevents the molten resin from flowing out of the injection cylinder from the supply port. The manufacturing apparatus according to claim 1 .

9. the injection cylinder has an injection port through which the molten resin is injected, The injection cylinder further includes a valve that prevents the molten resin from flowing out of the injection port. The manufacturing apparatus according to claim 1 .

10. a mold defining a cavity, and the molten resin is injected into the cavity; The manufacturing apparatus according to claim 1 .

11. a mold defining a plurality of cavities, and the molten resin is injected into the plurality of cavities; The manufacturing apparatus according to claim 1 .

12. The injection device further includes a sensor used to detect whether the injection plunger has contacted the pressing member or whether the injection plunger has separated from the pressing member. The manufacturing apparatus according to claim 1 .

13. the sensor is an optical sensor; The manufacturing apparatus according to claim 12 .

14. acquiring information corresponding to a change in sliding resistance between the injection cylinder and the injection plunger based on a change over time in the output from the sensor; The manufacturing apparatus according to claim 12 .

15. A molded product is manufactured by the manufacturing apparatus according to any one of claims 1 to 14. A method for producing a molded article, comprising:

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