Rubber injection molding machine, rubber injection molding method

Abstract

To provide a technology that can improve the performance of rubber injection molding machines. [Solution] A rubber injection molding machine 1 for molding rubber molded products, comprising an injection device 10 equipped with a plasticizing device 120 that plasticizes the molding material for the rubber molded product and supplies it to an injection cylinder, a plunger device 140 that has an injection cylinder and a plunger and injects the molding material supplied to the injection cylinder into the cavity of the mold using the plunger, a clamping device 20 that changes the mold from an open state to a closed state and further clamps the mold, and an ejector device 30 of the clamping device 20 that ejects the rubber molded product held in the mold in the open state, and the plasticizing device 120, plunger device 140, clamping device 20 and ejector device 30 each have an electric motor as a drive source.

Description

[Technical Field]

[0001] The present invention relates to a technique for producing a rubber molded product. [Background technology]

[0002] Conventionally, a vertical pre-plunger injection molding machine has been known for molding rubber molded products. It consists of a plasticizing unit and a plunger unit, which serves as an injection unit mounted on top of a mold clamping unit. In this injection molding machine, the plasticizing unit heats and rotates the screw to plasticize the rubber material. The material is then sent to the plunger unit, which then advances the plunger to inject the rubber material. This type of injection molding machine can often produce a larger injection volume than an inline screw injection molding machine. Furthermore, compared to screw injection, plunger injection reduces backflow of the rubber material backward in the injection direction, allowing for more accurate injection volume.

[0003] Generally, a hydraulic motor is used to rotate the screw of the plasticizing device, and a hydraulic cylinder is used as the drive mechanism for the plunger in the plunger device. As a related technique, an injection molding machine described in Patent Document 1 below is known. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Jikko No. 59-5555 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the embodiments of the present disclosure is to provide a technology that can improve the performance of a rubber injection molding machine. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0006] A rubber injection molding machine according to one embodiment is a rubber injection molding machine for molding rubber molded products, and is equipped with: a plasticizing device that plasticizes the molding material of the rubber molded product and supplies it to an injection cylinder; an injection device that has the injection cylinder and a plunger and a plunger that injects the molding material supplied to the injection cylinder into the cavity of a mold using the plunger; a clamping device that changes the mold from an open state to a closed state and further clamps the mold; and an ejector device of the clamping device that ejects the rubber molded product held in the mold in the open state, and is characterized in that the plasticizing device, the plunger device, the clamping device, and the ejector device each have an electric motor as a drive source. [Effects of the Invention]

[0007] The rubber injection molding machine disclosed herein is a rubber injection molding machine that molds rubber molded products, and is equipped with: a plasticizing device that plasticizes the molding material of the rubber molded product and supplies it to an injection cylinder; an injection device that has the injection cylinder and a plunger and a plunger that injects the molding material supplied to the injection cylinder into the cavity of a mold using the plunger; a clamping device that changes the mold from an open state to a closed state and further clamps the mold; and an ejector device of the clamping device that ejects the rubber molded product held in the mold in the open state, and since the plasticizing device, plunger device, clamping device, and ejector device each have an electric motor as a drive source, the performance of the rubber injection molding machine can be improved, and molding stability and power consumption can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an overall configuration of a rubber injection molding machine according to an embodiment. [Figure 2] 1 is a block diagram showing a configuration of a rubber injection molding machine according to an embodiment. FIG. [Figure 3] FIG. 1 is a schematic view showing a configuration of an injection device according to an embodiment. [Figure 4]FIG. 2 is a schematic diagram illustrating the configuration of a mold clamping unit and an ejector unit of the mold clamping unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been appropriately simplified. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. Furthermore, hatching has been omitted in some areas to avoid cluttering the drawings.

[0010] (Device configuration) Fig. 1 is a schematic diagram showing the overall configuration of a rubber injection molding machine according to an embodiment, and Fig. 2 is a block diagram showing the configuration. Fig. 3 is a schematic diagram showing the configuration of an injection device according to an embodiment.

[0011] 1 and 3, the rubber injection molding machine 1 according to this embodiment is a so-called vertical pre-plunger type injection molding machine (also called a PrePla™ type injection molding machine), and includes: a plasticizing device 120 that plasticizes the molding material for the molded product and supplies it to an injection cylinder 141; an injection device 10 that includes the injection cylinder 141 and a plunger 143 and injects the molding material supplied to the injection cylinder 141 (see FIG. 3) into the cavity of a mold 50 using the plunger 143; a mold clamping device 20 that is provided below the injection device 10 and that changes the mold 50 from an open state to a closed state and further clamps the mold; an ejector device 30 that is provided in the mold clamping device 20 and that ejects a molded product held in the mold 50 in the open state; a mold removal device 40 that is also provided in the mold clamping device 20; and a control device 70 (see FIG. 2). In this embodiment, the molded product of the rubber injection molding machine 1 is a rubber molded product, and the molding material is a rubber material. However, this is not limited to this, and it goes without saying that the rubber injection molding machine 1 can also manufacture plastic molded products other than rubber.

[0012] In this embodiment, the injection unit 10 is equipped with a moving device 160 that moves the injection unit 10 so that the molding material discharge port of the injection unit 10 can be moved toward and away from the mold of the mold clamping unit 20, and a rotary valve 180 that is located between the plasticizing unit 120 and the plunger unit 140 and is capable of shifting between an allowable state that allows the molding material to flow into the injection cylinder 141 and a restricting state that restricts the inflow. In addition, the mold clamping unit 20 is provided with a mold thickness adjustment device 220 that adjusts the vertical position of a movable platen 208 that holds the mold 50 when the mold is closed, in order to adjust the mold thickness of the mold 50.

[0013] The plasticizing device 120, plunger device 140, moving device 160, rotary valve 180, mold clamping device 20, mold thickness adjusting device 220 of mold clamping device 20, ejector device 30 of mold clamping device 20, and mold removal device 40 of mold clamping device 20 are each equipped with electric motors 510, 520, 530, 540, 550, 560, 570, and 580 as drive sources. In other words, these various devices are driven by electric motors rather than by fluid pressure such as hydraulics, so the rubber injection molding machine 1 can be said to be an all-electric injection molding machine in terms of its drive mechanism. If these electric motors are servo motors, they are all connected to the control device 70 and a power supply device via servo amplifiers (not shown).

[0014] The control device 70 is connected to and controls the plasticizing device 120, plunger device 140, moving device 160, rotary valve 180, mold clamping device 20, mold thickness adjusting device 220 of mold clamping device 20, ejector device 30 of mold clamping device 20, mold removal device 40 of mold clamping device 20, and mold 50. Specifically, it controls the driving of electric motors 510-580 equipped in various devices and heating mechanisms 610, 620, and 630, which will be described in detail later. In addition, the control device 70 may be controllably connected to a material supply device (not shown) that supplies molding material to the plasticizing device 120, or to driving devices such as compressors and valves when air is used instead of an electric motor, and may also be connected to switches such as limit switches and sensors.

[0015] The control device 70 has hardware such as a central processing unit (CPU), read-only memory (ROM), and random access memory (RAM), which work together to drive and control various devices. The control device 70 may also have an input / output unit to receive input from a user and output the input via a display, for example, to input and display various settings for the rubber injection molding machine 1. The control device 70 may be incorporated into either the injection device 10 or the clamping device 20, or may be provided independently as an operation panel or control panel near the clamping device 20, or may be implemented by an information processing device such as a personal computer (PC). Alternatively, the control devices for peripheral devices such as the heating mechanisms 610-630 may be distributed to each peripheral device.

[0016] The various devices described above will be described in detail below. First, the configuration of the injection device 10 will be described in detail. Figure 3 is a schematic diagram showing the configuration of the injection device according to this embodiment.

[0017] (Plasticizing device 120) As shown in FIG. 3, the plasticizing device 120 of the injection unit 10 extends substantially horizontally, its tip (the left end in the figure) connected to the rotary valve 180, and includes a hollow cylindrical plasticizing cylinder 121 for plasticizing the molding material therein. In FIG. 3, the cross section of the plasticizing cylinder 121 is indicated by hatching. For ease of explanation, the direction of extension of the plasticizing cylinder 121 will be referred to as the left-right direction in the following description. The plasticizing cylinder 121 does not necessarily need to extend horizontally; it may be provided vertically or at an angle. The plasticizing cylinder 121 has a heat medium passage around its periphery through which a heat medium circulates. The heat medium passage of the plasticizing cylinder 121 is not limited to one zone, but may be divided into multiple zones, with heat mediums of different temperatures being supplied to each zone. In this embodiment, the temperature of each zone is preferably controlled to be higher toward the tip. By controlling the temperature in this manner, the molding material in the plasticizing cylinder 121 can be plasticized well.

[0018] The heat medium passage is connected to a heating mechanism 610 (see FIG. 2) serving as a heat medium supply device provided in the plasticizing device 120. The heating mechanism 610 is preferably controlled by the control device 70. The type of heat medium here may be water, hot water, or heat medium oil. The heating mechanism 610 has been described as being configured as a heat medium supply device using a heat medium passage formed on the outer periphery of the plasticizing cylinder 121 to control the temperature of the plasticizing cylinder 121, but it may also be configured as an electric heater using an electric heating wire or an electromagnetic induction heating device, in which case a cooling device using a fan (blower) and air blower may also be used in combination.

[0019] A supply port 122 through which the molding material is supplied is provided near the rear end of the plasticizing cylinder 121. Here, the angle (direction) at which the supply port 122 is provided in the circumferential direction of the plasticizing cylinder 121 is on the lower side of the plasticizing cylinder 121, but it can be freely installed on the upper side, side (including diagonally upward, diagonally downward, etc.), etc. A molding material supply device (not shown) may be provided adjacent to the supply port 122, and the molding material can be supplied into the plasticizing cylinder 121 through the supply port 122 by the supply device.

[0020] A block-shaped flange 123 is provided at the rear end of the plasticizing cylinder 121. A space communicating with the internal space of the plasticizing cylinder 121 is defined in the flange 123, and the rear end of a screw 124 (described later) is inserted therein for relative rotation. In FIG. 3 , the cross section of the flange 123 is indicated by hatching. An electric motor 510 for rotating the screw 124 is provided above the flange 123 via a bracket 512 that is approximately L-shaped in side view, with its drive shaft 511 facing left and right. This electric motor 510 is preferably a servo motor capable of controlling the amount of rotation with high precision. The electric motor 510 is not limited to being provided above the flange 123; it may be provided at any position, such as the bottom, rear, or side, as long as it can rotate the screw 124. However, in consideration of the balance of the rubber injection molding machine 1, this position is preferable.

[0021] The screw 124 is disposed within the internal space of the plasticizing cylinder 121 and is formed in a generally cylindrical shape extending in the same direction as the plasticizing cylinder 121. The axis of the screw 124 preferably coincides with the axis of the plasticizing cylinder 121 and is disposed so as to be capable of relative rotation without displacement. The outer periphery of the screw 124 is provided with spiral flights spaced at equal intervals, and rotation of the screw 124 transports the plasticized rubber material between the flights toward the tip, i.e., toward the plunger device 140. The screw 124 forms, from its rear end, a feed zone, a compression zone, and a metering zone. The shaft diameter of the feed zone is relatively narrow compared to the other zones, while the shaft diameter of the compression zone becomes relatively wider toward the front, and the shaft diameter of the metering zone becomes relatively wider. In this embodiment, the front portion of the screw 124 is not provided with a backflow prevention mechanism and only transports the plasticized rubber material. Therefore, the tip is conical. The screw 124 is preferably subjected to corrosion-resistant and abrasion-resistant processing for rubber molding.

[0022] The rear portion of the screw 124 is inserted into the flange portion 123 so as to be relatively rotatable, and a screw connector (not shown) or the like may be used at the rear end thereof, but a driven pulley 125 is fixed thereto so as to be rotatable together with the screw connector. Meanwhile, a drive pulley 513 is fixed to a drive shaft 511 of the electric motor 510 so as to be rotatable together. A circular belt 126 is stretched around the drive pulley 513 and the driven pulley 125. A plurality of teeth are formed on the outer circumferential surface of each pulley, and teeth that mesh with the teeth are formed on the inner circumferential surface of the belt 126. Therefore, the belt 126 can be moved circumferentially in conjunction with the rotation of the drive pulley 513 by the electric motor 510, and the screw 124 can be rotated via the driven pulley 125.

[0023] (plunger device 140) As shown in FIG. 3, the plunger device 140 has an injection cylinder 141 that is a generally hollow cylinder extending in the vertical direction. The injection cylinder 141 receives the molten rubber material (hereinafter referred to as the molten material) supplied from the plasticizing device 120 in its internal space. In FIG. 3, the cross section of the injection cylinder 141 is shown hatched. Note that the injection cylinder 141 does not necessarily need to extend horizontally, and may be provided vertically or at an angle. The upper end of the injection cylinder 141 is fixed to a front plate 142 that is generally rectangular in plan view, with the center of the generally rectangular shape in plan view inserted through the front plate. Similar to the plasticizing cylinder 121, the injection cylinder 141 has a heat medium passage on its outer periphery through which a heat medium circulates. The heat medium passage of the injection cylinder 141 is not limited to one zone, but may be divided into multiple zones, with heat mediums of different temperatures being supplied to each zone.

[0024] In many cases, it is advantageous for molding to control the temperature of the injection cylinder 141 so that it is higher than the temperature of the plasticizing cylinder 121. For this reason, in this embodiment, the injection cylinder 141 and the plasticizing cylinder 121 have separate heat medium temperature control systems. Specifically, the heat medium passage is connected to a heating mechanism 620 (see FIG. 2 ) serving as a heat medium supply device provided in the plunger device 140. The heating mechanism 620 is preferably controlled by the control device 70. Possible types of heat medium used here include water, hot water, and heat medium oil. While the heating mechanism 620 has been described as a heat medium supply device using a heat medium passage to control the temperature of the injection cylinder 141, it may also be configured as an electric heater using an electric heating wire or an electromagnetic induction heating device. In this case, a cooling device using a fan (blower) and air blower may also be used.

[0025] A cylindrical plunger 143 with a conical bottom end is inserted into the internal space of the injection cylinder 141 so as to be movable up and down. In the following description, downward movement of the plunger 143 will be referred to as forward movement and upward movement as backward movement. A gap is provided between the inner wall defining the internal space and the peripheral surface of the plunger 143, particularly at the front, to prevent the molten material from entering. Alternatively, a sealing member (not shown) may be interposed.

[0026] Two guide rods 144 are erected on the upper surface of the front plate 142, preferably four guide rods 144 near the four corners of the front plate 142. Each guide rod 144 extends upward through an intermediate plate 145 (described later), and its upper end is inserted into and fixed to a rear plate 146 that is approximately rectangular in plan view. An electric motor 520 for moving the plunger 143 forward and backward is mounted on one side (left side in the figure) of the rear plate 146 via a bracket 522 so that its drive shaft 521 faces up and down. This electric motor 520 is preferably a servo motor capable of controlling the amount of rotation with high precision. Note that the electric motor 520 is not limited to being mounted on one side of the rear plate 146, but may be mounted anywhere, such as the top, bottom, or other side (right side in the figure) of the rear plate 146, as long as it can move the plunger 143. However, in consideration of the balance of the rubber injection molding machine 1, this position is preferable.

[0027] The non-threaded portion of a ball screw 147 is inserted through the central portion of the approximately square rear plate 146 in plan view, preferably coaxially with the plunger 143, and is supported by a bearing (not shown) for relative rotation.

[0028] An intermediate plate 145 is provided between the front plate 142 and the rear plate 146, and is guided by a guide rod 144 to be able to move up and down. A ball screw nut 148 is fixed to the upper surface of the central portion of the intermediate plate 145, which is generally square in plan view, and a threaded portion of a ball screw 147 is threadedly engaged with and inserted into this ball screw nut 148 so as to be relatively rotatable. The upper end of a plunger 143 (or the rear portion of a connector or the like connected to the plunger 143) is connected to the lower surface of the central portion of the intermediate plate 145, which is generally square in plan view. Therefore, the plunger 143 extends downward from the intermediate plate 145 and is inserted into the internal space of the injection cylinder 141 from the rear end side thereof.

[0029] A driven pulley 149 is fixed to the upper end of the ball screw 147 so as to rotate integrally therewith. Meanwhile, a drive pulley 523 is fixed to the drive shaft 521 of the electric motor 520 so as to rotate integrally therewith. A circular belt 150 is stretched around the drive pulley 523 and the driven pulley 149. A plurality of teeth are formed on the outer circumferential surface of each pulley, and teeth that mesh with the teeth are formed on the inner circumferential surface of the belt 150. Therefore, the belt 150 can be moved circumferentially in conjunction with the rotation of the drive pulley 523 by the electric motor 520, and the ball screw 147 can be rotated via the driven pulley 149. As the ball screw 147 rotates, the intermediate plate 145 and the plunger 143 can be moved up and down via the ball screw nut 148 in accordance with the rotation direction of the drive shaft 521 of the electric motor 520. Therefore, the electric motor 520 can move the plunger 143 forward and backward within the injection cylinder 141.

[0030] (Mobile device 160) On one side (left side in the drawing) of the front plate 142 that supports the injection cylinder 141, an electric motor 530 for raising and lowering the entire plunger device 140 provided in the moving device 160 is provided via a plate-shaped bracket 532 so that its drive shaft 531 faces up and down. This electric motor 530 is preferably a servo motor that can control the amount of rotation with high precision. Note that the electric motor 530 is not limited to being provided on one side of the front plate 142, but may be provided on the other side, upper part, lower part, or any other position as long as it can move the plunger device 140. However, in consideration of the balance of the rubber injection molding machine 1, it is preferable to provide the electric motor in this position.

[0031] Furthermore, a bracket 161 for fixing the plasticizing device 120 is provided on the other side of the front plate (the right side in the figure), which is formed in a roughly L-shape in side view. A support column 162, which serves as a fixing member for the plasticizing device 120, is attached downward from the underside of the bracket 161. The lower end of the support column 162 is connected to the upper surface of the plasticizing cylinder 121 of the plasticizing device 120. The lower end of the support column 162 may be connected to the plasticizing cylinder 121 and the flange 123, or may be connected to the flange 123 instead of the plasticizing cylinder 121. The front plate 142 and the plasticizing device 120 are integrally formed by the fixing member consisting of the bracket 161 and the support column 162. It goes without saying that the fixing member may be provided in a different shape if the plasticizing cylinder 121 of the plasticizing device 120 is installed vertically or obliquely.

[0032] The upper ends of two ball screws 163 extending in the vertical direction are rotatably supported on the lower surface of the front plate 142 by bearings 164 provided within the front plate 142. In this embodiment, there are two ball screws 163, but there may be one or three or more. The lower ends of the ball screws 163 are individually inserted into two hollow cylindrical portions 165 that are erected so as to extend upward on the upper surface of the upper movable platen 208 of the mold clamping unit 20 located below the moving device 160. A ball screw nut 166 is fixed to the upper end of the cylindrical portion 165, and the threaded portion of the ball screw 163 is threadedly engaged with and inserted into this ball screw nut 166 so as to be rotatable relative to the ball screw 163.

[0033] Two guide rods 167, preferably four guide rods 167, are erected on the upper surface of the upper movable platen 208 near the four corners of the upper movable platen 208 in a plan view. The guide rods 167 are slidably inserted into guide holes (not shown) formed in the front plate 142. Note that the guide rods 167 may also serve as the above-mentioned guide rods 144, that is, the guide rods 144 may be eliminated, and the upper ends of the guide rods 167 may pass through the front plate 142 and the intermediate plate 145 and be connected to the rear plate 146.

[0034] A driven pulley 168 is fixed to the non-threaded portion of the ball screw 163 so as to rotate integrally therewith. Meanwhile, a drive pulley 533 is fixed to the drive shaft 531 of the electric motor 530 so as to rotate integrally therewith. A circular belt 169 is stretched around the drive pulley 533 and the driven pulley 168. Therefore, the belt 169 can be moved circumferentially in conjunction with the rotation of the drive pulley 533 by the electric motor 530, and the ball screw 163 can be rotated via the driven pulley 168. As the ball screw 163 rotates, the ball screw 163 moves up and down relative to the ball screw nut 166 in accordance with the rotation direction of the drive shaft 531 of the electric motor 530. This movement causes the elements integrated with the front plate 142 together with the ball screw 163, specifically, the plasticizing device 120, the plunger device 140, the electric motor 530 of the moving device 160, and the rotary valve 180 and nozzle 190 (described later), to move up and down. Therefore, the injection device 10 can be moved forward / backward by the electric motor 530, and can be moved to both the nozzle touch position and the maintenance position.

[0035] Note that the moving device 160 is capable of moving the injection unit 10 to both the nozzle touch position and the maintenance position, and therefore high accuracy of positioning is not essential. Therefore, instead of a servo motor, another electric motor may be used for the electric motor 530, or a combination of an electric motor and a spring may be used. Also, an actuator other than an electric motor, such as a hydraulic cylinder, may be used.

[0036] (Rotary Valve 180) As shown in FIG. 3, the rotary valve 180 has a generally cylindrical valve element 182 inserted into the connection block 181, which is connected to the tip of the plasticizing cylinder 121 of the plasticizing device 120, through an insertion hole formed on the side (toward the rear or front in FIG. 3) of the connection block 181. The insertion hole has an axis facing the side. The insertion hole faces the side. The upper surface of the connection block 181 is connected to the tip of the injection cylinder 141 of the plunger device 140. A horizontal connection passage 181A is formed between the insertion hole of the connection block 181 and the internal space of the plasticizing cylinder 121, fluidly connecting the two. An upper connection passage 181B is formed between the insertion hole of the connection block 181 and the internal space of the injection cylinder 141, fluidly connecting the two. A lower connection passage 181C is formed between the insertion hole of the connection block 181 and the nozzle 190 (details of which will be described later) provided below the valve element 182.

[0037] The horizontal connecting passage 181A has a flow path that narrows from its end on the plasticizing cylinder 121 side, from its connection with the internal space of the plasticizing cylinder 121, toward the valve body 182 side; that is, the inner wall surface has a tapered shape, and the cross-sectional area of ​​the flow path is narrowed compared to the cross-sectional area of ​​the internal space of the plasticizing cylinder 121. Similarly, the upper connecting passage 181B has a flow path that narrows from its upper end, from its connection with the internal space of the injection cylinder 141, toward the valve body 182 side; that is, the inner wall surface has a tapered shape, and the cross-sectional area of ​​the flow path is narrowed compared to the cross-sectional area of ​​the internal space of the injection cylinder 141. In this case, the angle of the conical tapered surface at the tip of the plunger 143 and the angle of the tapered surface of the upper connecting passage 181B may be approximately the same angle or may be slightly different. As a result, when the plunger 143 advances to its most forward position during injection, the amount of molten material remaining in the internal space of the injection cylinder 141 is eliminated or reduced to an extremely small amount, thereby preventing old molten material from remaining inside the injection cylinder 141.

[0038] The valve element 182 and the insertion hole are close to each other to prevent the molten material from entering the gap defined between them. The gap may be sealed with a sealing member (not shown). Meanwhile, a concave flow path (concave flow path) through which the molten material passes is formed on the circumferential surface of the valve element 182 at a portion that contacts the upper connecting passage 181B or the horizontal connecting passage 181A when the valve element 182 rotates. In FIG. 3, the cross section of the valve element 182 is shown hatched. It can be seen that the concave flow path is formed in the portion 120 to 140 degrees around the axis of the valve element 182, and the valve element 182 is recessed toward the axis. The portion of the valve element 182 other than the concave flow path remains as a circumferential surface, forming a closed portion through which the molten material cannot pass. The end of the valve element 182 protrudes from the connection block 181, and the driven pulley 183 is fixed to the protruding portion so as to be rotatable integrally therewith.

[0039] Meanwhile, on one side (left side in FIG. 3) of the connection block 181, an electric motor 540 for rotating the rotary valve of the rotary valve 180 is mounted via a bracket 542 so that its drive shaft 541 faces to the side (toward the rear or front in FIG. 3). It is preferable to have a heat insulating material between the bracket 542 and the connection block 181. This electric motor 540 is preferably a servo motor that can control the amount of rotation with high precision. It is not limited to being mounted on the side of the connection block 181, but may be mounted on any other side, top, bottom, or other position as long as it can rotate the valve element 182. However, in consideration of the balance of the rubber injection molding machine 1, it is preferable to mount the electric motor in this position.

[0040] A drive pulley 543 is fixed to the drive shaft 541 of the electric motor 540 so as to be rotatable together with the drive pulley 543. A circular timing belt 184, such as a heat-resistant type, is wound around the drive pulley 543 and driven pulley 183. A plurality of teeth are formed on the outer circumferential surface of each pulley, and teeth that mesh with the teeth are formed on the inner circumferential surface of the timing belt 184. Therefore, the timing belt 184 can be moved circumferentially in conjunction with the rotation of the drive pulley 543 by the electric motor 540, and the valve element 182 can be rotated via the driven pulley 183. This rotation of the valve element 182 makes it possible to switch the feed direction of the molten material. Specifically, the rotary valve 180 can be switched between an allowable state in which the horizontal connecting passage 181A and the upper connecting passage 181B are connected to the recessed flow path of the valve body 182, and the lower connecting passage 181C is closed at its closing portion to allow the supply of molten material from the plasticizing cylinder 121 to the injection cylinder 141, and a restrictive state in which the horizontal connecting passage 181A is closed at its closing portion, and the lower connecting passage 181C is connected to the recessed flow path of the valve body 182 to restrict the supply of molten material from the plasticizing cylinder 121 to the injection cylinder 141. In FIG. 3, the rotary valve 180 is in the restrictive state. In this restrictive state, molten material can be injected from the injection cylinder 141 through the nozzle 190 into the cavity of the mold in the mold clamping unit 20. However, the valve body 182 of the rotary valve 180 may be configured to realize the restrictive state and the injectable state at different positions.

[0041] The position where valve element 182 stops after rotating may be determined by abutting a member, etc. In this case, a different electric motor may be used instead of a servo motor for electric motor 540, or an actuator other than a motor, for example, an actuator using fluid pressure such as oil pressure or gas pressure, may be used.

[0042] Furthermore, the connection block 181 may be provided with a heating mechanism using a heat medium, similar to the plasticizing cylinder 121 of the plasticizing device 120 and the injection cylinder 141 of the plunger device 140. In other words, a heat medium flow path may be formed in the connection block 181. Possible types of heat medium include water, hot water, and heat medium oil. The heating mechanism may be configured as a heat medium supply device using a heat medium path, or may be configured as an electric heater using an electric heating wire or an electromagnetic induction heating device. Furthermore, the temperature may be controlled by the heating mechanism 620 of the plunger device 140, i.e., controlled to the same temperature as the injection cylinder 141.

[0043] (Nozzle 190) The nozzle 190 is formed in the shape of a hollow cylinder extending in the vertical direction, and its upper end is connected to the lower surface of the connection block 181. The internal space of the nozzle 190 is connected to the lower connection passage 181C of the connection block 181 described above. Note that in FIG. 3, the cross section of the nozzle 190 is shown by hatching. The upper connection passage 181B in the connection block 181 and the flow passage from the injection cylinder 141 of the plunger device 140 to the rotary valve 180 are also provided vertically, so that a flow passage is formed in a substantially straight line from the plunger device 140 to the nozzle 190, although the rotary valve 180 is interposed in the middle. A discharge port 191 communicating with the internal space is formed at the lower end of the nozzle 190. The area around this discharge port 191 forms the contact surface of the mold clamping unit 20 with the mold.

[0044] The nozzle 190 may be provided with a heating mechanism using a heat medium, similar to the plasticizing cylinder 121 of the plasticizing device 120 and the injection cylinder 141 of the plunger device 140. That is, a heat medium flow path may be formed in the nozzle 190. Possible types of heat medium include water, hot water, and heat medium oil. The heating mechanism may be configured as a heat medium supply device using a heat medium path, or may be configured as an electric heater using an electric heating wire or an electromagnetic induction heating device. Furthermore, the temperature may be controlled by the heating mechanism 620 of the plunger device 140, that is, controlled to the same temperature as the injection cylinder 141.

[0045] Next, the configurations of the mold clamping unit 20 and the ejector unit 30 of the mold clamping unit will be described in detail. Fig. 4 is a schematic diagram showing the configurations of the mold clamping unit and the ejector unit of the mold clamping unit according to this embodiment.

[0046] (mold clamping device 20) 4, the mold clamping device 20 is composed of a mold clamping mechanism section 230 and a bed 200 that supports the mold clamping mechanism section 230, and this mold clamping mechanism section 230 is composed of a toggle link mechanism 210 that opens / closes and clamps a lower fixed mold 206 and an upper movable mold 207 that constitute the mold 50, a mold thickness adjustment device 220 that adjusts the distance between the lower fixed platen 204 and the upper movable platen 208 in the mold closed state, a mold removal device 40 that moves the lower fixed mold 206 and its mounting bolster section 216 in the horizontal direction, and an ejector device 30 that ejects the molded product from the mold. Details of these devices will be described later.

[0047] The bed 200 is composed of a base frame 201 that is roughly rectangular when viewed from above, vertically extending pillars 203 provided at the four corners of the base frame 201, and an upper plate connected to the upper ends of the pillars 203, and the upper surface of the upper plate is connected to the lower surface of a lower fixed plate 204 that is roughly rectangular when viewed from above.

[0048] Tie bar insertion holes (not shown) through which tie bars 205 extending in the vertical direction are inserted are formed near the four corners of the lower fixed platen 204 in a plan view. The upper surface of the lower fixed platen 204 (hereinafter referred to as the lower fixed platen 204 including a mounting bolster portion 216 described later) is configured so that a lower fixed mold 206 can be attached. In this embodiment, the manufactured rubber molded product is held in the lower fixed mold 206 until it is ejected upward by the ejector device 30. In addition, the upper surface of the lower fixed platen 204 is configured so that the lower fixed mold 206 can slide, as will be described later.

[0049] An upper movable platen 208 is provided above the lower fixed platen 204 so as to be movable up and down, and has an upper movable mold 207 attached to its underside which can be mated with the lower fixed mold 206. 207A in the upper movable mold 207 indicates a nozzle touch portion that abuts against the periphery of the discharge port 191 of the nozzle 190, and the upper movable platen 208 is formed with a nozzle insertion hole (conical portion) 208A that communicates with the nozzle touch portion 207A and whose cross-sectional area in the horizontal direction decreases downward.

[0050] The upper ends of the tie bars 205 are connected to the vicinity of the four corners in plan view of the lower surface of the upper movable platen 208. As described above, the tie bars 205 are inserted into the tie bar insertion holes of the lower fixed platen 204, and further, their lower ends are connected to the vicinity of the four corners in plan view of the housing platen 209, which has a substantially rectangular shape in plan view and is disposed below the lower fixed platen 204. A toggle link mechanism 210 is provided between the lower fixed platen 204 and the housing platen 209.

[0051] An electric motor 550 for mold opening / closing and mold clamping is mounted on one side of the housing platen 209 via a bracket 542 so that its drive shaft 551 faces up and down. This electric motor 550 is preferably a servo motor capable of controlling the amount of rotation with high precision. The electric motor 550 is not limited to being mounted on one side of the housing platen 209, but may be mounted anywhere, such as on another side, upper part, or lower part, as long as it can rotate a ball screw 211 (described later). However, in consideration of the balance of the rubber injection molding machine 1, this position is preferable. A ball screw 211 extending up and down is inserted through the center of the housing platen 209, which is approximately rectangular in plan view. The non-threaded portion of the ball screw 211 is rotatably supported by the housing platen 209 via a bearing (not shown).

[0052] The toggle link mechanism 210 is a so-called double toggle mechanism and, as is well known, includes two toggle links, such as a first toggle link 210A, a second toggle link 210B, and a third toggle link 210C, with a ball screw 211 positioned therebetween. The first toggle link 210A is connected to the lower fixed platen 204 via a link holder provided on the underside of the lower fixed platen 204, and the second toggle link 210B is connected to the housing platen 209 via a link holder provided on the upper surface of the housing platen 209. The toggle link mechanism 210 may include additional toggle links, such as a fourth toggle link. The threaded portion of the ball screw 211 is threadedly engaged with and inserted through a ball screw nut 212, which is fixed to a crosshead 210D to which inner links, such as the third toggle link 210C, are coupled, so as to be capable of relative rotation.

[0053] A driven pulley 213 is fixed to the lower end of the non-threaded portion of the ball screw 211 so as to rotate integrally therewith. Meanwhile, a drive pulley 553 is fixed to a drive shaft 551 of the electric motor 550 so as to rotate integrally therewith. A circular belt 214 is stretched around the drive pulley 553 and the driven pulley 213. A plurality of teeth are formed on the outer circumferential surface of each pulley, and teeth that mesh with the teeth are formed on the inner circumferential surface of the belt 214. Therefore, the belt 214 can be moved circumferentially in conjunction with the rotation of the drive pulley 553 by the electric motor 550, and the ball screw 211 can be rotated via the driven pulley 213. As the ball screw 211 rotates, the crosshead 210D moves up and down via the ball screw nut 212 in accordance with the rotation direction of the drive shaft 551 of the electric motor 550. In response to the movement of the crosshead 210D, each link of the toggle link mechanism 210 operates, and the upper movable platen 208 can be moved up and down via the housing platen 209 and the tie bar 205.

[0054] (Mold thickness adjustment device 220) 4, an electric motor 560 for adjusting mold thickness provided in the mold thickness adjusting device 220 is provided on the other side of the housing platen 209 of the mold clamping unit 20 with its drive shaft facing up and down. This electric motor 560 is preferably a servo motor capable of controlling the amount of rotation with high precision. Note that the electric motor 560 is not limited to being provided on the other side of the housing platen 209, but may be provided in any position such as on another side, above, or below as long as it can rotate the tie bar 205. However, in consideration of the balance of the rubber injection molding machine 1, it is preferable to provide the electric motor 560 in this position.

[0055] A gear 563 is fixed to the drive shaft of the electric motor 560 so as to rotate integrally therewith. Furthermore, a thread is cut into the lower end of each tie bar 205, and a tie bar nut 221 is screwed onto the lower end of the tie bar nut 221, which is provided at a position on the housing platen 209 corresponding to the tie bar 205. A gear 222 is fixed to the outer periphery on the lower side of the tie bar nut 221 so as to rotate integrally therewith. Furthermore, a large gear 223 is provided in the center of the approximately rectangular shape in plan view on the lower surface of the housing platen 209 so as to rotate relatively. The gear 563 of the electric motor 560 directly meshes with the gear 222 of an adjacent tie bar nut 221 or with the large gear 223. Note that the gear 222 may be rotated using a chain instead of the large gear 223.

[0056] With this structure, when gear 563 is rotated via the drive shaft of electric motor 560 in mold thickness adjusting device 220 of mold clamping unit 20, gear 222 of one adjacent tie bar nut 221 rotates, and gear 222 of another tie bar nut 221 rotates via large gear 223 meshing with it. Tie bar nuts 221 rotate integrally with the rotation of each gear 222, and tie bar nuts 221, and therefore housing platen 209, move up and down along tie bar 205 according to the rotation direction of the drive shaft of electric motor 560. This makes it possible to adjust the distance between upper movable platen 208 and housing platen 209, i.e., the effective length of tie bar 205, and makes it possible to accommodate changes to various molds to be attached, even if they are changed to ones with different thicknesses.

[0057] The mold thickness adjusting device 220, which includes the electric motor 560, tie bar 205, tie bar nut 221, and various gears, may use a system in which the tie bar nut 221 is rotated by a chain and a gear meshing with the chain, instead of a system in which rotational force is transmitted by meshing gears. The electric motor 560 may be another type of electric motor, or an actuator using fluid pressure such as oil pressure or gas pressure may be used.

[0058] (Mold removal device 40) As shown in FIG. 4 , the lower fixed mold 206 can be pulled out toward one side of the mold clamping unit 20 (the left side in FIG. 4 ) by a mold removal device 40 attached to the mold clamping unit 20. Specifically, a guide groove 215 is formed on the lower fixed platen 204 for moving the lower fixed mold 206 and its mounting bolster 216. A conveying section 401 is formed on one side of the lower fixed platen 204 and extends in the left-right direction, serving as a path for moving the lower fixed mold 206 and the mounting bolster 216. Stoppers (not shown) that can come into contact with the mounting bolster 216 are preferably provided at both ends of the conveying section 401. These stoppers are used to position the lower fixed mold 206 at an ejection position where a molded product held by the lower fixed mold 206 is ejected and at a molding position where the lower fixed mold 206 can be mated with the upper movable mold 207. The mounting bolster 216 functions as part of the lower fixed platen 204, particularly when it is in the molding position.

[0059] At one end of the conveying section 401, an electric motor 580 for moving the lower fixed mold of the mold removal device 40 is mounted via a plate-shaped bracket 582 so that its drive shaft (not shown) faces the left-right direction. A ball screw nut 402 is fixed to the mounting bolster 216. Meanwhile, a ball screw 403 is fixed to the drive shaft of the electric motor 580 so as to rotate integrally therewith, either directly or via a circular belt. As a result, when the drive shaft of the electric motor 580 rotates, the ball screw 403 rotates in the same direction, and the mounting bolster 216, and therefore the lower fixed mold 206, can be slid between the removal position and the molding position via the ball screw nut 402 in either the left or right direction depending on the rotation direction. Note that in FIG. 4, the lower fixed mold 206 and the mounting bolster 216 at the removal position are indicated by dashed lines as imaginary lines.

[0060] The mold removal device 40, including the conveying unit 401, ball screw nut 402, ball screw 403, and electric motor 580, may be configured such that the lower fixed mold 206 does not slide laterally, but rather the lower fixed mold 206 and the mounting bolster unit 216 are mounted on a rotary table centered on a single axis, and the lower fixed mold 206 and the mounting bolster unit 216 are rotated between the removal position and the molding position. In this case, the electric motor 580 is mounted on the lower fixed platen 204 with its drive shaft facing up and down, and the rotary table is attached directly or indirectly to the drive shaft. The electric motor 580 may be a servo motor or another electric motor. An actuator other than a motor, such as an actuator using fluid pressure such as hydraulic or gas pressure, may also be used. This molding machine can be realized even if the mold clamping unit does not include a mold removal device. As shown in FIG. 1, the mold removal device 40 is located on the opposite side of the main body of the rubber injection molding machine 1 from the plasticizing device 120. It is preferable to install the mold removal device 40 in this position in consideration of the balance of the rubber injection molding machine 1. However, the mold removal device 40 may be installed perpendicular to the plasticizing device 120 in a plan view (on the front or back side in FIG. 1) or on the same side as the plasticizing device 120.

[0061] (Ejector device 30) 4, an ejector unit 30 that ejects upward a rubber molded product held in the lower fixed mold 206 is provided on the underside of the transfer unit 401 on the removal position side of the mold clamping unit 20. The ejector unit 30 is equipped with an ejector electric motor 570. A plurality of support units 301 (four in this case) that also serve as guide rods are vertically extended hang down from the underside of the transfer unit 401, and a support plate 302 that is approximately square in plan view and is used to attach the electric motor 570 is fixed to the tip end of each support unit 301. In addition, in the case of a machine in which the mold clamping unit 20 does not have a mold removal unit 40, the ejector unit 30 is provided below the lower fixed mold 206 during molding.

[0062] An electric motor 570 is mounted on the other side of the support platen 302 via a plate-shaped bracket 572 so that its drive shaft 571 faces up and down. This electric motor 570 is preferably a servo motor that can control the amount of rotation with high precision. Note that the electric motor 570 is not limited to being mounted on the other side of the support platen 302, and may be mounted on one side or another side, or anywhere else as long as it can rotate a ball screw nut 303 (described later). However, in consideration of the balance of the rubber injection molding machine 1, it is preferable to mount the electric motor in this position.

[0063] A ball screw nut 303 is provided in the center of the support plate 302, which is generally square in plan view, so as to be relatively rotatable but not movable in the vertical direction. A threaded portion of a ball screw 304 is threadedly engaged with and inserted into the ball screw nut 303. A ball screw support plate 305, which is generally square in plan view, is guided by the support portion 301 so as to be able to move up and down freely. The non-threaded portion of the ball screw 304 is fixed to the ball screw support plate 305 so as not to rotate.

[0064] A driven pulley 306 is fixed to the cylindrical surface of the ball screw nut 303. Meanwhile, a drive pulley 573 is fixed to the lower end of a drive shaft 571 of an electric motor 570 so as to rotate integrally therewith. A circular belt 307 is stretched around the drive pulley 573 and the driven pulley 306. A plurality of teeth are formed on the outer circumferential surface of each pulley, and teeth that mesh with the teeth are formed on the inner circumferential surface of the belt 307. Therefore, the belt 307 can be moved circumferentially in conjunction with the rotation of the drive pulley 573 by the electric motor 570, and the ball screw nut 303 can be rotated via the driven pulley 306 in accordance with the rotation direction of the drive shaft 571. The rotation of the ball screw nut 303 can move the ball screw 304 up and down in accordance with the rotation direction. The upper end of the non-threaded portion of the ball screw 304 forms an ejector rod, which can be inserted into ejector rod insertion holes formed in the lower fixed mold 206 and the mounting bolster 216, respectively.

[0065] A known ejector plate or an ejector pin attached to the ejector plate and projecting from and retracting from the cavity CA surface, which will be described later, may be provided inside the lower fixed mold 206. The ejector device 30 may be configured such that the ball screw 304 rotates to move the ball screw nut 303 and a plate or rod to which the ball screw nut 303 is fixed up and down, thereby ejecting the rubber molded product from the lower fixed mold 206 using an ejector rod attached to the plate or rod.

[0066] (Mold 50) As described above, the mold 50 attached to the mold clamping unit 20 is composed of the lower fixed mold 206 and the upper movable mold 207. In the lower fixed mold 206 and the upper movable mold 207, the molten material injected from the injection unit 10 is vulcanized in the cavity CA formed by the mold alignment. Therefore, it is preferable to control the temperature of the lower fixed mold 206 and the upper movable mold 207 to a temperature higher than that of the injection unit 10, for example, the injection cylinder 141 or the nozzle 190. Therefore, in this embodiment, the lower fixed mold 206 and the upper movable mold 207 preferably use an electric heater such as a cartridge heater that heats with an electric heating wire as the heating mechanism 630 (see FIG. 2 ). It is preferable that the heating mechanism 630 be driven and controlled by the control device 70. Note that the heating mechanism 630 is not limited to an electric heater, and a heat medium supplying device that controls the temperature using a heat medium such as water, hot water, or heat transfer oil, or an electromagnetic induction heating device may also be used.

[0067] (device operation) Next, a manufacturing method for producing a rubber molded product will be described, as an example of the operation of the rubber injection molding machine 1. The rubber used in the rubber molded product of the present invention may be any type, including natural rubber, nitrile rubber, acrylic rubber, ethylene propylene rubber, silicone rubber, and fluororubber. The concept of rubber in the present invention also includes various elastomers that require vulcanization, and may be a polymer of any of the above materials. This manufacturing method is carried out by controlling each device with the control device 70. First, the temperature of the plasticizing cylinder 121 of the plasticizing device 120 is controlled to 50°C to 130°C by the heating mechanism 610, depending on the type of molding material. Next, a ribbon-shaped material (e.g., an endless string-shaped material with a cross section of approximately 5 mm x 50 mm) is supplied into the plasticizing cylinder 121 from the supply port 122 on the lower side of the plasticizing cylinder 121 by the supply device, as the screw 124 is rotated by the electric motor 510. The rotation speed of the screw 124 is 50 to 100 revolutions per minute. -1 ) and the supplied rubber material is melted in the plasticizing cylinder 121 as the screw 124 rotates and is sent forward.

[0068] At this time, the valve element 182 of the rotary valve 180 is set to an allowable state that allows the molten material to flow into the injection cylinder 141, and the molten material is sent from the plasticizing device 120 to the injection cylinder 141 of the plunger device 140. The temperature of the injection cylinder 141 is preferably higher than that of the plasticizing cylinder 121 of the plasticizing device 120 and is preferably controlled to 55°C to 135°C. At this time, the electric motor 520 of the plunger device 140 controls the back pressure, i.e., the plunger 143 is advanced to press the molten material, and the molten material in front of the plunger 143 is maintained at a predetermined pressure while the plunger 143 gradually retreats, thereby executing a metering process. When a servo motor is used as the electric motor 520 that drives the plunger device 140, the retreat of the plunger 143 can be detected by a rotary encoder attached to the servo motor to indicate the completion of the metering process. This allows for more accurate detection of the position of the plunger 140. Furthermore, if a servo motor is also used for the electric motor 510 that drives the plasticizing device 120, it is possible to stop the servo motor quickly upon receiving a signal that the plunger 140 has reached the metering completion position. Furthermore, when a servo motor is used for the plasticizing device 120, the rotation speed of the screw 124 in the metering process can be set at a more accurate setting, and metering can be performed with the plastic state of the rubber molding material, including shear heat, stabilized to a desired state.

[0069] Around the time of the end of the metering process, the electric motor 550 is driven on the mold clamping unit 20 side, and the toggle link mechanism 210 is operated to place the lower fixed mold 206 and the upper movable mold 207 in a mold-closed state and then in a mold-clamped state. In the case of the toggle link mechanism 210 using an electric motor 550 such as a servo motor, the toggle link of the toggle link mechanism 210 is extended and the mold is clamped, and the power consumption of the electric motor 550 is extremely small. Therefore, even when molding a rubber molded product, which has an extremely long molding time (vulcanization time including pressure dwell) compared to general resin molded products, the power consumption required for mold clamping can be significantly reduced. Furthermore, in this embodiment, the nozzle 190 provided in the injection unit 10 is constantly in contact with the nozzle touch portion 207A of the upper movable mold 207 by the moving device 160.

[0070] As the supply of molten material to the injection cylinder 141 continues and the plunger 143 retreats to a preset position (determined by the molding volume of the rubber molded product) previously set in the control device 70, the rotation of the screw 124 of the plasticizing device 120 is stopped, and the valve motor 540, which is the drive source for the valve element 182 provided in the rotary valve 180, is driven to switch the valve element 182 to a restricted state. By switching to the restricted state, the communication between the plasticizing cylinder 121 and the injection cylinder 141 is cut off, and the injection cylinder 141 and the nozzle 190 are connected to each other. At this time, it is preferable that the nozzle 190 be temperature-controlled to be approximately the same temperature as the injection cylinder 141.

[0071] After switching to the restricted state (injection state), the electric motor 520 of the plunger device 140 is driven, and the molten material stored in front of the plunger 143 is supplied from the discharge port 191 of the nozzle 190 through the sprue in the upper movable mold 207 to the cavity CA formed between the lower fixed mold 206 and the upper movable mold 207. After the injection process, a pressure-holding process is performed to apply a force to the plunger 143 in the forward direction. Note that with hydraulic rubber injection molding machines such as those described in Patent Document 1, variations in the pressure-holding switch position during the injection process can cause variations in the injection amount or inconsistent pressure during pressure-holding, resulting in unstable molding. Therefore, particularly in rubber molding, flashing occurs when the injection amount is too large or the pressure during pressure-holding is too high. Conversely, sink marks occur due to insufficient filling if the injection amount is too small or the pressure during pressure-holding is too low. Therefore, flashing has been considered unavoidable when molding rubber products using hydraulic rubber injection molding machines. However, when a servo motor is used for the electric motor 520 of the plunger device 140, in an injection device 10 in which the plasticizing device 120 and plunger device 140 are provided separately, the above problem can be significantly improved, along with stable metering, and the occurrence of burrs can be significantly reduced. Note that during this pressure holding step, the plunger 143 may be further pushed to its most forward position to perform a pressure holding step. After the injection step and / or pressure holding step are completed, the valve element 182 of the rotary valve 180 on the injection device 10 side is switched back to the permissive state, and the metering step for the next rubber molded product is carried out.

[0072] Meanwhile, the mold clamping state continues on the mold clamping device 20 side. The lower fixed mold 206 and the upper movable mold 207 are heated and temperature-controlled by the heating mechanism 630 to about 180°C to 240°C, which is higher than the temperature of the molten material before injection, and a solidification step is carried out to advance the vulcanization of the rubber molded product.

[0073] After the solidification process is completed, the electric motor 550 of the mold clamping device 20 is driven again, and the lower fixed mold 206 and the upper movable mold 207 are opened using the toggle link mechanism 210. At this time, the rubber molded product is held by the lower fixed mold 206 and released from the mold. Next, the electric motor 580 of the mold removal device 40 is driven, and the lower fixed mold 206 holding the rubber molded product is slid to the removal position. Once it is confirmed that the lower fixed mold 206 has reached the removal position after sliding, the electric motor 570 of the ejector device 30 is driven, and the ball screw 304 moves upward, and the ejector rod ejects the rubber molded product upward from the lower fixed mold 206. After ejection, the rubber molded product is grasped by, for example, a multi-axis robot hand and transported to a predetermined position. Thereafter, the electric motor 570 is driven again, and the ball screw 304 moves downward to the reference position, and the electric motor 580 is driven, and the lower fixed mold 206 is returned to the molding position. When the lower fixed mold 206 is returned to the molding position, the electric motor 550 is driven again, and the toggle link mechanism 210 closes and clamps the lower fixed mold 206 and the upper movable mold 207, and the process waits again until the molten material that has undergone the metering process is injected.

[0074] According to the present embodiment described above, at least the plasticizing device 120, plunger device 140, rotary valve 180, mold clamping device 20, and ejector device 30 of the mold clamping device 20 in the rubber injection molding machine 1 can be driven by electric motors 510, 520, 540, 550, and 570. Therefore, compared to control using a drive device using fluid pressure, improved controllability (control accuracy) and a faster molding cycle due to improved response can be achieved. This is also extremely advantageous in terms of energy savings. In the rubber injection molding machine 1 of the present disclosure, servo motors are used for the electric motor 510 that drives the plasticizing device 120, the electric motor 520 that drives the plunger device 140, the electric motor 550 that drives the mold clamping device 20, and the electric motor 570 that drives the ejector device 30, thereby improving the performance of the rubber injection molding machine 1, and achieving molding stability and reduced power consumption. It is also preferable to drive all of the drive mechanisms included in the rubber injection molding machine 1, such as the injection device 10, the mold clamping device 20, and the ejector device 30 of the mold clamping device 20, using a drive source that uses electricity or gas pressure rather than using hydraulic pressure, thereby preventing deterioration of the cleanliness of the molding space due to oil leaks, generation of oil mist, etc.

[0075] In this embodiment, the mold clamping unit 20 moves the upper movable platen 208 located above the lower fixed platen 204 up and down using the toggle link mechanism 210, but this is not limited to this. For example, the lower fixed platen 204 may be fixedly provided as an upper fixed platen relative to the housing platen 209 by supports or tie bars 205, the upper movable platen 208 may be disposed as a lower movable platen between the upper fixed platen and the housing platen 209, and the lower movable platen may be moved up and down while being guided by the tie bars 205. In this case, the injection unit 10 is placed above the upper fixed platen, and the toggle link mechanism 210 is provided between the housing platen 209 and the lower movable platen. Similar to the above, an electric motor 550 that operates the toggle link mechanism 210 is attached to the housing platen 209. The ejector unit 30 is preferably provided below the lower movable platen.

[0076] Furthermore, in this embodiment, the supply path of the molten material is switched by the rotary valve 180, but this is not limiting. A slide-type flow path switching valve may be used instead of the rotary valve 180. The slide-type flow path switching valve has a cylindrical portion that is movable in the axial direction (for example, toward the rear or front in FIG. 3 ), and has two flow paths formed at different positions in the axial direction: a first flow path that connects the internal spaces of the plasticizing cylinder 121 of the plasticizing device 120 and the injection cylinder 141 of the plunger device 140; and a second flow path that connects the internal space of the injection cylinder 141 and the internal space of the nozzle 190. By moving this cylindrical portion back and forth in the axial direction, it is possible to switch between a state in which the first flow path, the plasticizing cylinder 121, and the injection cylinder 141 are connected to each other and the injection cylinder 141 and the nozzle 190 are blocked (a state for the metering process), and a state in which the second flow path, the injection cylinder 141, and the nozzle 190 are connected to each other and the plasticizing cylinder 121 and the injection cylinder 141 are blocked (a state for the injection process). Alternatively, a switching valve such as a flow path switching valve including the rotary valve 180 may not be used. For example, when the plasticizing device 120 uses a mechanism in which the screw 124 moves back and forth, the screw 124 is advanced, and the conical surface at the tip of the screw 124 is pressed against a tapered surface in the connection block 181 where the valve body 182 is not provided, thereby closing the horizontal connection path 181A, thereby preventing backflow of the molten material into the plasticizing cylinder 121 when the plunger 143 is advanced. When molten material is supplied from the plasticizing cylinder 121 to the injection cylinder 141, the flow path from the plasticizing cylinder 121 to the nozzle 190 may be closed by a known closing means, or the flow path may be prevented from flowing into the nozzle 190 by the molten material already present therein without any closing means.

[0077] In addition, in this embodiment, the rubber injection molding machine 1 has been described as a vertical pre-plunger type injection molding machine, but this is not limited to this. The rubber injection molding machine 1 may be constructed as a horizontal pre-plunger type injection molding machine by installing the injection unit 10 and the mold clamping unit 20 adjacent to each other in the left-right direction.

[0078] In addition, the rubber injection molding machine 1 according to this embodiment has the following features: a moving device that moves the injection device so that the discharge port of the molding material in the injection device can be moved toward or away from the mold; Further provided with the moving device has a moving motor as a drive source, the injection device includes a valve located between the injection cylinder and the plasticizing cylinder, the valve being capable of shifting between an allowable state in which the molding material is allowed to flow into the injection cylinder and a restricting state in which the molding material is restricted from flowing into the injection cylinder; a valve motor that is a drive source for the valve; and the moving device is provided at approximately the center of the injection device in the up-down direction, the mold is provided below the injection device, and the mold clamping device is provided below the mold, The tip of the plasticizing cylinder is connected to one side of the injection cylinder, and the rear end of the plasticizing cylinder is provided with an electric motor of the plasticizing device; an electric motor of the injection device is provided at an upper end of the injection device and on the opposite side of the injection cylinder; an electric motor of the mold clamping device is provided on the opposite side of the injection cylinder in the mold clamping device, the removal device and its motor are provided above the electric motor of the mold clamping device, the moving motor is provided on the opposite side of the moving device from the injection cylinder, The valve motor is provided on the opposite side of the injection cylinder. This is one of its characteristics. According to this feature, excessive load due to the weight of the molding machine is not applied to any part of the molding machine, and the rubber injection molding machine 1 can be made into a vertical type machine with excellent balance.

[0079] Although the embodiments of the invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims. [Explanation of symbols]

[0080] 1. Rubber injection molding machine 10 Injection device 120 Plasticizing equipment 121 Plasticizing Cylinder 140 Plunger device 141 Injection cylinder 160 Mobile Device 180 rotary valve 182 Valve 190 nozzles 191 Discharge port 20 Mold clamping device 206 Lower fixed mold 207 Upper movable mold 210 Toggle link mechanism (toggle mechanism) 30 Ejector device 50 molds 510~580 Electric motor 620, 630 Heating mechanism (first heating mechanism, second heating mechanism) CA Cavity

Claims

1. A rubber injection molding machine for molding a rubber molded product, an injection device including a plasticizing device that plasticizes the molding material of the rubber molded product and supplies it to an injection cylinder; and a plunger device that has the injection cylinder and a plunger and injects the molding material supplied to the injection cylinder into a cavity of a mold using the plunger; a mold clamping device that changes the mold from an open state to a closed state and further clamps the mold; an ejector device of the mold clamping device that ejects the rubber molded product held in the mold in a mold open state; Equipped with The plasticizing device, the plunger device, the mold clamping device, and the ejector device each have an electric motor as a drive source. Rubber injection molding machine.

2. The electric motor is a servo motor 2. The rubber injection molding machine according to claim 1.

3. a moving device that moves the injection device so that the discharge port of the molding material in the injection device can be moved toward and away from the mold; Further provided with The moving device has a moving motor as a driving source.

2. The rubber injection molding machine according to claim 1.

4. The injection device a valve located between the plasticizing device and the plunger device, the valve being capable of shifting between an allowable state in which the molding material is allowed to flow into the injection cylinder and a restricting state in which the molding material is restricted from flowing into the injection cylinder; a valve motor that is a drive source for the valve; The rubber injection molding machine according to claim 1, further comprising:

5. The valve is a rotary valve.

5. The rubber injection molding machine according to claim 4.

6. a first heating mechanism that adjusts the temperature of the injection unit using a heat medium, an electric heating wire, or an electromagnetic induction heating device; a second heating mechanism that adjusts the temperature of the mold using a heat medium, an electric heating wire, or an electromagnetic induction heating device; Further provided with All of the drive mechanisms of the injection device, the mold clamping device, and the ejector device included in the rubber injection molding machine are driven by a drive source using electricity or gas pressure.

2. The rubber injection molding machine according to claim 1.

7. The mold holding the rubber molded product at the time of demolding is configured to be slidable from a mold mating position where it can be mated with another mold to a removal position where the rubber molded product is removed, The electric motor of the ejector device is With the mold slid to the removal position, the protruding portion is advanced to eject the rubber molded product from the mold.

2. The rubber injection molding machine according to claim 1.

8. A rubber injection molding machine for molding a rubber molded product, an injection device including a plasticizing device that plasticizes the molding material of the rubber molded product and supplies it to an injection cylinder; and a plunger device that has the injection cylinder and injects the molding material supplied to the injection cylinder into a cavity of a mold using a plunger; a mold clamping device having a toggle mechanism that changes the mold from an open state to a closed state in the vertical direction and further clamps the mold; an ejector device of the mold clamping device that ejects the rubber molded product held in the mold in a mold open state; Equipped with The plasticizing device, the plunger device, the mold clamping device having the toggle mechanism, and the ejector device each have an electric motor as a drive source. Rubber injection molding machine.

9. A rubber molding method for a rubber injection molding machine that molds a rubber molded product, comprising: Rubber injection molding machine an injection device including a plasticizing device that uses an electric motor to drive the molding material for the rubber molded product to plasticize it and supply it to an injection cylinder; and a plunger device that has the injection cylinder and a plunger and uses an electric motor to drive the molding material supplied to the injection cylinder to inject it into a cavity of a mold using the plunger; a mold clamping device that uses an electric motor to drive the mold to change from an open state to a closed state and further clamp the mold; an ejector device of the mold clamping device that uses an electric motor to drive and eject the rubber molded product held in the mold in an open state; It is equipped with The temperatures of the plasticizer, the injection cylinder, and the mold are controlled so that the temperatures of the molding material applied to the plasticizer, the injection cylinder, and the mold are gradually increased in this order. Rubber injection molding method.

10. The temperature of the plasticizing cylinder of the plasticizing device and the injection cylinder of the plunger device is controlled by heating them using an electric heating wire, a heating medium, or an electromagnetic induction heating device; The temperature control of the plasticizing cylinder of the plasticizing device and the temperature control of the injection cylinder of the plunger device are performed separately in separate systems. The rubber injection molding method according to claim 9.

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