Rotary injection molding apparatus

Abstract

To provide a rotary injection molding apparatus simplified in its constitution, easy in maintenance and eliminating the waste of a material after molding by dispensing with the provision of a runner to each of a plurality of molds on a rotary table.SOLUTION: The rotary injection-molding apparatus includes a mold (3) having a cavity 31b for forming a molded article (B), and a rotary table (2) on which a plurality of molds (3) are mounted in a circumferential direction, and a forming material (A) is injected and poured into the cavity 31b of the mold (3) sequentially corresponding to rotation of the rotary table (2) from an injection unit (4) by an operation of an extrusion cylinder (5) to form the molded article (B). The mold (3) includes a plurality of injection port 31b communicating with the cavity 31a. 31a.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rotary injection molding apparatus. [Background technology]

[0002] Conventionally, a rotary injection molding machine has been used to mold rubber products. This machine has multiple molds mounted on a rotary table, and as the rotary table rotates, molding material is injected from an injection unit into the corresponding molds in sequence to form the molded product.

[0003] For example, the rotary injection molding device shown in Patent Document 1 includes a disk-shaped rotary table equipped with multiple mold clamping devices arranged circumferentially, a support unit that supports the rotary table so that it can rotate freely around a vertical axis, a rotary drive unit that intermittently drives and rotates the rotary table, and a vertical injection unit that injects molding material into the mold after the mold has been clamped.

[0004] The schematic configuration of the parts involved in the injection and injection molding operations of such a conventional rotary injection molding apparatus is shown in Figures 4 and 5. In rotary injection molding apparatus 100, mold 103 is composed of upper mold 103a and lower mold 103b, with multiple cavities 105, which are molding spaces, formed between them. Multiple molds 103 are mounted on rotary table 102, and as rotary table 102 rotates, molding material A is injected and injected from injection unit 106 into the corresponding molds 103 in sequence, thereby forming molded product B. Injection unit 106 is composed of extrusion cylinder 108 that extrudes molding material A, and nozzle 107, which is the injection part for molding material A.

[0005] In this configuration, a conventional rotary injection molding apparatus 100 has runners 104a on the mold 103 that branch the flow of molding material to multiple cavities 105 in the mold 103. That is, on the upper mold 103a of the mold 103, runner plates 104 each having a runner 104a serving as a flow path for the molding material and an injection port 104b for the molding material are stacked.

[0006] Before molding, injection unit 106 is in a raised position away from mold 103, as shown in Fig. 4. During molding, injection unit 103 moves downward (in the direction of arrow T), and nozzle 107 abuts against injection port 104b of runner plate 104, as shown in Fig. 5. In this state, extrusion cylinder 108 is actuated to extrude molding material A into extrusion port 108a, whereby molding material A is injected from nozzle 107. The injected molding material A passes through runner 104a, branches, and is injected into multiple cavities 105, thereby forming molded product B. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-44178 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional rotary injection molding machines such as those described above have a runner for each of the multiple molds on the rotary table, which means the rotary injection molding machine has a complex configuration, requires a lot of maintenance, and wastes a lot of material after molding. The present invention has been made to solve these problems, and its purpose is to provide a rotary injection molding apparatus that eliminates the need to provide a runner for each of the multiple molds on the rotary table, thereby simplifying the configuration of the rotary injection molding apparatus, making maintenance easier, and reducing waste of material after molding. [Means for solving the problem]

[0009] In order to achieve the above object, the first invention is a rotary injection molding apparatus comprising a mold having a cavity for molding a molded product, and a rotary table on which a plurality of molds are mounted in the circumferential direction, in which molding material is injected and poured from an injection unit by actuation of an extrusion cylinder into the corresponding mold cavities in sequence as the rotary table rotates, thereby molding a molded product, the mold has a plurality of injection ports communicating with the cavity; The injection unit is characterized by being provided with a runner that branches the flow of molding material to the multiple injection ports of the mold. The second invention is characterized in that in the first invention, the mold is composed of at least an upper mold and a lower mold, and has a plurality of cavities, which are molding spaces, between them. The third invention of the present invention is characterized in that, in the first or second invention, the runner is kept at a temperature that ensures the fluidity of the molding material by a heat retention means that is common to the extrusion cylinder. [Effects of the Invention]

[0010] According to the present invention, by providing a runner on the injection unit side, there is no need to provide a runner for each of the multiple molds on the rotary table, which simplifies the configuration of the rotary injection molding device, makes maintenance easier, and reduces waste of material after molding. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view showing a schematic configuration of a rotary injection molding apparatus according to an embodiment of the present invention. [Figure 2] 1 is a partially enlarged cross-sectional view showing the schematic configuration of a rotary injection molding apparatus according to an embodiment of the present invention, showing the state before a molding material is injected into a mold. [Figure 3] 1 is a partially enlarged cross-sectional view showing the schematic configuration of a rotary injection molding apparatus according to an embodiment of the present invention, showing the state after a molding material has been injected into a mold. [Figure 4] FIG. 1 is a partially enlarged cross-sectional view showing the schematic configuration of a conventional rotary injection molding device, showing the state before molding material is injected into the mold. [Figure 5] FIG. 1 is a partially enlarged cross-sectional view showing the schematic configuration of a conventional rotary injection molding device, showing the state after a molding material has been injected into a mold. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a rotary rubber injection molding apparatus for molding rubber products will be described as an example of the rotary injection molding apparatus. Note that this embodiment is merely an example of the present invention and should not be construed as being limited thereto, and design modifications are possible within the scope of the present invention.

[0013] 1 to 3, the rotary injection molding apparatus 1 of this embodiment is equipped with a mold 3 having a cavity 31b for molding a molded rubber product B, and a rotary table 2 on which a plurality of molds 3 are mounted in the circumferential direction. The rotary table 2 is placed on a machine stand on the floor on which the rotary injection molding apparatus 1 is installed.

[0014] As shown in FIG. 2, the injection unit 4 of the rotary injection molding device 1 is composed of an extrusion cylinder 5 that extrudes molding material A made of unvulcanized rubber, and a nozzle portion 6 that is the injection portion of molding material A.

[0015] The nozzle section 6 includes a nozzle 61 provided at the tip for injecting the molding material A into the mold 3, and a runner 62 for supplying the molding material A to the nozzle 61.

[0016] As the rotary table 2 rotates, molding material A made of unvulcanized rubber is injected and injected from the injection unit 4 by the operation of the extrusion cylinder 5 into the corresponding cavities 31b of the mold 3, thereby forming a molded rubber product B. The rotary injection molding apparatus 1 of this embodiment has a single injection unit 4, that is, one injection unit 4 arranged vertically and equipped with a plurality of nozzles 61.

[0017] Furthermore, the upper mold 31 of the mold 3 is provided with a plurality of injection ports 31a that communicate with the respective cavities 31b, and a plurality of nozzles 61 are arranged vertically on the injection unit 4 side corresponding to the respective injection ports 31a. In this embodiment, as shown in Fig. 1, four injection ports 31a are provided in the mold 3. Accordingly, four cavities 31b (enough for four pieces) are also provided in the mold 3, and four nozzles 61 are also provided in the injection unit 4.

[0018] The injection unit 4 is provided with a runner 62 that is continuous with the extrusion port 51 of the extrusion cylinder 5 and that branches the flow of the molding material A to the multiple injection ports 31a of the mold 3. This will be described in detail below.

[0019] The mold 3 is composed of at least an upper mold 31 and a lower mold 32, with a plurality of cavities 31b, which are molding spaces, between them. The mold 3 may also be configured with a middle mold disposed between the upper mold 31 and the lower mold 32. The upper mold 31 of the mold 3 has a plurality of injection ports 31a, each of which communicates with the plurality of cavities 31b.

[0020] The runner 62 is a flow path that branches the flow of molding material A to the multiple injection ports 31a, and during molding, the multiple nozzles 61 at the branching ends of the runner 62 each come into contact with the multiple injection ports 31a and the molding material A is injected.

[0021] In the conventional example shown in Figures 4 and 5 above, the runners 104a that branch the flow of molding material A were provided for each of the multiple molds 103 on the rotary table 102, but in this embodiment, the runners 62 that branch the flow of molding material A are provided on the side of a single injection unit 4.

[0022] In this embodiment, by providing runner 62 on the injection unit 4 side, it is no longer necessary to provide a runner for each of the multiple molds 3 on the rotary table 2 as in the conventional example. This simplifies the configuration of the rotary injection molding apparatus 1, makes maintenance easier, and also reduces waste of material after molding.

[0023] As shown in Fig. 1, a plurality of molds 3 (six molds 3a, 3b, 3c, 3d, 3e, and 3f in this embodiment) are mounted at equal intervals in the circumferential direction on a turntable 2. The turntable 2 is intermittently rotated by a rotary drive means (motor) (not shown), and moves the plurality of molds 3 sequentially from 3a to 3f to positions corresponding to the injection units 4. In Fig. 1, the rotation direction of the turntable 2 is indicated by an arrow S in a counterclockwise direction.

[0024] The injection unit 4 is moved up and down between an elevated position away from the mold 3 and a lowered position in contact with the mold 3 by a lifting mechanism (not shown).

[0025] During molding, the mold 3 is fixed and held in a closed state by a mold clamping mechanism (not shown). During molding, the mold 3 is heated to the vulcanization temperature of the molding material A by a heating means such as a heater.

[0026] The injection unit 4 includes an extrusion cylinder 5 , and extrudes the molding material A, which is unvulcanized rubber, from an extrusion port 51 to a nozzle portion 6 .

[0027] The injection unit 4 is provided with a runner 62 that is continuous with the extrusion port 51 of the extrusion cylinder 5 and branches the flow of molding material A to multiple injection ports 31a of the mold 3, and the molding material A is injected from multiple nozzles 61 at the tips branched by this runner 62.

[0028] In this way, by providing the runner 62 that branches the flow of molding material on the injection unit 4 side, there is no need to provide a runner for each of the multiple molds 3, which simplifies the configuration of the rotary injection molding device 1, makes maintenance easier, and reduces waste of material after molding.

[0029] The injection unit 4 also includes a heat retention section 7 around the extrusion cylinder 5. The heat retention means of the heat retention section 7 is, for example, an oil flow path that surrounds the extrusion cylinder 5, and oil heated to a predetermined temperature is passed through this oil flow path to maintain the temperature of the extrusion cylinder 5 at a temperature that is lower than the vulcanization temperature of the molding material A, which is unvulcanized rubber, and that ensures the fluidity of the molding material A.

[0030] Furthermore, in the nozzle section 6, the runner 62 is kept warm by a heat retention means that is common to the extrusion cylinder 5. That is, in the nozzle section 6, an oil flow path of the same system as the heat retention section 7 described above is provided around the runner 62, so that the runner 62 is kept warm at a temperature that is below the vulcanization temperature of the molding material A and that ensures the fluidity of the molding material A. By sharing the heat retention means between the extrusion cylinder 5 and the runner 62 in this way, efficient heat retention is achieved.

[0031] Next, the molding operation of the rotary injection molding apparatus 1 of the present invention will be described. First, the rotation of the rotary table 2 causes the plurality of molds 3 to rotate and move in sequence to positions corresponding to the injection units 4, and molding is performed by injecting and pouring molding material A from the injection units 4 into the cavities 31b of the molds 3. These operations are driven and controlled by a rotation control means and a motor driver, not shown.

[0032] Here, before molding, the injection unit 4 is in an elevated position away from the mold 3 as shown in FIG.

[0033] Then, when the target mold 3 reaches a position corresponding to the injection unit 4, the injection unit 4 moves downward (in the direction of arrow T), and the tip side of the nozzle 61 is pressed against the injection port 31a of the mold 3 as shown in Figure 3.

[0034] In this state, the extrusion cylinder 5 of the injection unit 4 is actuated, and molding material A, which is unvulcanized rubber, is injected from the nozzle 61 through the extrusion port 51 and the runner 62. For example, in this case, the injection unit 4 rotates a screw (not shown) in the extrusion cylinder 5 in a predetermined direction, and the molding material A is extruded from the extrusion port 51 by the screw feed action of the screw, passes through the runner 62 and is injected from the nozzle 61. Note that the means for extruding the molding material A in the extrusion cylinder 5 is not limited to the screw type.

[0035] During this injection operation, the extrusion cylinder 5 and the runner 62 are kept at a temperature below the vulcanization temperature of the molding material A and at a temperature that ensures the fluidity of the molding material A (for example, 60 to 70°C in the case of fluororubber) by the heat retention means of the heat retention section 7, so that the molding material A is injected smoothly.

[0036] The molding material A injected from the nozzle 61 is then poured into the cavity 31b through the injection port 31a of the mold 3, and then the mold 3 is heated by a heating means at the vulcanization temperature of the molding material A for the required time (for example, in the case of fluororubber, 180°C for 240 seconds), thereby vulcanizing the molding material A in the cavity 31b and turning it into a molded rubber product B.

[0037] After molding, the injection unit 4 moves to a raised position away from the mold 3 and prepares for injection into the next mold 3 that is sent there by the rotation of the turntable 2.

[0038] After molding, the mold 3 is sent by the rotation of the turntable 2 to a position not corresponding to the injection unit 4, and while it is stationary, the upper mold 31 and the lower mold 32 are opened to remove the molded product B. Taking into consideration the cooling time of the mold after molding and the mold opening process, the removal position of this molded product is preferably a position 180° from the injection unit 4 (the position of the mold 3d shown in Figure 1).

[0039] The above operations are repeated to perform molding in sequence. [Industrial Applicability]

[0040] The rotary injection molding apparatus according to the present invention is not limited to the molding of rubber products, but can also be applied to the molding of resin products. [Explanation of symbols]

[0041] 1 Rotary injection molding machine 2 Rotating Tables 3. Mold 4 injection unit 5. Extrusion cylinder 6 Nozzle section 7 Heat retention section 31a Inlet 31b cavity 61 nozzles 62 Runner A Molding material B Molded product

Claims

1. A rotary injection molding apparatus comprising a mold having a cavity for molding a molded product, and a rotary table on which a plurality of molds are mounted in a circumferential direction, in which molding material is injected and poured from an injection unit by actuation of an extrusion cylinder into corresponding mold cavities in sequence as the rotary table rotates, thereby molding a molded product, the mold has a plurality of injection ports communicating with the cavity; A rotary injection molding apparatus characterized in that the injection unit is provided with a runner that branches the flow of molding material toward the injection port of the mold.

2. 2. The rotary injection molding apparatus according to claim 1, wherein the mold is composed of at least an upper mold and a lower mold, and has a plurality of cavities serving as molding spaces therebetween.

3. 3. The rotary injection molding apparatus according to claim 1, wherein the runner is maintained at a temperature that ensures the fluidity of the molding material by a heat retaining means that is common to the extrusion cylinder.

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