JP2797615B2 - Multicolor molded products - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multicolor molded article injection-molded by sequentially injecting a plurality of molten resins into a cavity formed in a mold.

[Conventional technology]

In general, for example, when an audio cassette half is injection-molded, the molten metal that has flowed through the mold in a cavity between a mold that forms the outer surface of the cassette half and a core that forms the inner surface of the cassette half. The product is formed by supplying resin through a gate.

[Problems to be solved by the invention]

By the way, in this case, if a normal type gate is provided on the mold corresponding to the outer surface of the cassette half, there is a problem that an uneven gate mark remains on the outer surface of the formed cassette half and the appearance is poor. In particular, it is desired that the gate position for injecting the secondary injection material (transparent resin) for molding the window portion of the cassette half, which is a two-color molded product, has no problem in appearance and function.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a gate in opposition to the surface of a molded product, and not to recognize a gate mark, to cause no problem in appearance, and to provide a gate. It is an object of the present invention to provide a multicolor molded product that can be designed to have a large shape, can significantly improve the fluidity of a resin, and can be easily and smoothly injection-molded.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a multicolor molded article injection-molded by sequentially injecting a plurality of molten resins into a cavity formed in a mold, comprising: a primary molded part; Consisting of a secondary molding part surrounded by molding parts,
Gate traces due to the valve gate are formed on the surface of the secondary molded portion, and the gate trace due to the valve gate has an irregular shape.

[Action]

In the multicolor molded article of the present invention, by using a valve gate when injection molding the secondary molded portion, the mark of the valve gate is not unsightly, and the mark of the valve gate is not a circle such as a triangle, a square, or a star. By adopting a different shape, the design is improved, the valve gate can no longer be distinguished from the mark, and the valve gate can be designed large, and the fluidity of the resin during secondary molding can be greatly improved. In addition, the pressure in the mold during the secondary molding can be kept low, so that excessive pressure can be prevented from being applied to the primary molded portion during the secondary molding, and the occurrence of defects such as deformation of the primary molded portion can be prevented. Can be prevented beforehand, and a good quality product can be easily and smoothly injection-molded.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a perspective view showing a cassette half according to an embodiment of the present invention. The cassette half C has a band-shaped transparent portion (secondarily formed portion) 1 formed at a central portion and the transparent portion 1. Colored parts (primary molded parts) 2, 3 formed on both sides of the
A pair of connecting portions (primary molding portions) 4 connecting these colored portions 2 and 3 is formed. Submarine gate marks 6 at the time of primary molding are formed on a pair of upright edges 5 on the front surface of the colored portion 3, and a triangular valve gate mark 7 is formed at the center of the outer surface of the transparent portion 1. Are formed.

As the injection molding die for two-color molding the cassette half C, for example, the one shown in FIGS. 2 and 3 is used. That is, the injection mold is provided with a fixed mold plate 10 that forms the outer surface of the cassette half C, and is provided so as to be able to approach and separate from the fixed mold plate 10 and the inner surfaces of the colored portions 2 and 3. The movable mold plate 11 forming the
1 and a movable body 12 which forms the inner surface of the transparent portion 1 and is movably provided. And
A passage 13 for supplying the primary injection material is formed on the mating surface of the fixed mold plate 10 and the movable mold plate 11, and a position of the cavity corresponding to the rising edge 5 on the front surface of the cassette half C is formed from this passage 13. The submarine gate 14 is formed before reaching. Further, a valve gate 15 having a triangular shape in a plan view is formed in the fixed mold plate 10 at the position of the cavity corresponding to the center of the outer surface of the transparent portion 1 of the cassette half C.

As shown in FIG. 3, a cylindrical bush 16 is mounted inside the fixed mold plate 10, and a heat insulating space is provided around the cylindrical bush 16.
17 are formed. A funnel-shaped tip member 18 is screwed to a tip portion of the cylindrical bush 16 by a screw portion 19.On the inside and outside portions of the screw portion 19, each tip surface 20, 20 of the bush 16 is provided. The configuration is such that 21 and the rear end surfaces 22, 23 of the front end member 18 are in close contact with each other.
In the screw portion 19, a rotation preventing pin 24 is inserted from the outer peripheral side of the tip member 18 to the bush 16. Further, the tip member 18 is mounted in a recess 25 formed in the fixed mold plate 10, and the rear end 26 of the inner wall surface of the fixed mold plate 10 constituting the recess 25 has a straight shape having no slope. It is formed in a curved surface, and is in close contact with the rear end of the outer peripheral surface of the distal end member 18. And the recess of the fixed mold plate 10
The valve gate (resin injection port) 15 is formed at the center of 25. Further, the inner wall surface 27 other than the rear end portion of the fixed mold plate 10 has a tapered surface whose diameter decreases toward the front end so that the solidified resin can be easily removed. A predetermined gap 28 is formed between the tip member 18 and the recess 25 of the fixed mold plate 10 except for the rear end.
28 is set to be small during thermal expansion. Furthermore, a heater 30 is mounted on a step portion 29 formed on the outer periphery of the tip member 18, and is covered with a tubular member 31 fitted to the tip member 18 by shrinkage fitting. The heater 30 is integrally connected to a heater (not shown) mounted on the outer periphery of the bush 16 and has one temperature sensor (not shown) mounted in the mounting hole 32 of the bush 16. ).

A resin passage 33 for molten resin is formed inside the bush 16 and the tip member 18. In addition, the tip member
A support member 34 is mounted on the bush 16 side inside 18, and the support member 34 is formed by connecting an outer cylinder 35 and an inner cylinder 36 by a plurality of support plate portions 37. In the resin passage 33, a movable rod 38 is disposed so as to be able to reciprocate along the axis thereof, and the distal end of the movable rod 38 passes through a reduced diameter portion 39, and the opening shape of the valve gate 15, A slightly smaller triangular gate closure 40 is provided. further,
The tip member 18 and the support member 34 mounted therein.
A rotation preventing member for preventing rotation of the support member 34
41 are provided. The movable rod 38 is reciprocated while being supported and guided by the inner cylinder 36 of the support member 34, and the movable rod 38 is provided so as not to rotate in a plane orthogonal to the axis thereof.

When two-color molding of the cassette half C is performed by using the injection molding die configured as described above, the movable mold plate 11 is tightly closed to the fixed mold plate 10 and the movable mold body 12 is clamped. In a state in which the primary injection material (colored resin) supplied through the passage 13 is in close contact with the fixed mold plate 10, the primary injection material (colored resin) is supplied to the submarine gate 14.
Into the cavity through the colored part 3, the connecting part 4,
4. The colored portion 2 is formed.

Then, after the completion of the primary molding, the movable mold body 12 is separated from the fixed mold plate 10, and in a state where the secondary injection material filling space is formed, the movable rod 38 is moved along the axis thereof,
The gate closing portion 40 of the movable rod 38 is pulled out from the valve gate 15. Thereby, the secondary injection material (transparent resin) supplied through the resin passage 33 is filled into the secondary injection material filling space through the valve gate 15. Subsequently, when the filling of the resin is completed, the movable rod 38 is moved, and the gate closing portion 40 of the movable rod 38 is inserted into the valve gate 15. In this case, the movable rod 38 reciprocates in the inner cylinder 36 of the support member 34, and the movement is supported and guided by the inner cylinder 36, so that the tip of the movable rod 38 is blurred or in a plane perpendicular to its axis. The valve gate 15 does not rotate smoothly at
Can be opened and closed.

The cassette half C thus secondary-formed is
The space between the fixed mold plate 10 and the movable mold plate 11 is opened, and the mold is protruded by a protruding pin provided on the movable mold plate 11 side to be smoothly released. In this case, in the obtained cassette half C, the primary molding is performed by the submarine gate method,
Submarine gate mark 6 formed on the edge 5 of the colored portion 3
Is small and inconspicuous, and the secondary molding is performed by the valve gate method, so that the valve gate mark 7 formed at the center of the surface of the transparent portion 1 is flat and has no irregularities.
Since it has a triangular shape, it is not unsightly as a gate mark, and the design is improved. In addition, since the gate shape can be designed to be large, the fluidity can be greatly improved and the pressure in the mold can be kept low. Therefore, it is possible to reduce the pressure applied to the colored portions 2 and 3 and the connecting portion 4 which are the primary forming portions during the secondary molding, and to suppress the deformation of the colored portions 2 and 3 and the connecting portion 4. Thus, a high-quality product can be easily and smoothly formed.

The shape of the valve gate is not limited to the triangular shape of the present embodiment, but various shapes such as a polygonal shape and a star shape can be adopted.

〔The invention's effect〕

As described above, the present invention is directed to a multicolor molded article injection-molded by sequentially injecting a plurality of molten resins into a cavity formed in a mold, comprising a primary molded part, and a primary molded part. Since the gate trace by the valve gate is formed on the surface of the secondary molded part and the gate trace by the valve gate is formed in a different shape, By using a valve gate when injection molding the molded part, the valve gate trace is not unsightly, and the design is improved by making the valve gate trace a different shape other than circular such as triangle, square, star, The valve gate mark can no longer be discriminated and there is no problem in appearance, and the valve gate can be designed large, greatly improving the fluidity of the resin during secondary molding. As a result, the pressure in the mold at the time of the secondary molding can be kept low, and therefore, it is possible to prevent excessive pressure from being applied to the primary molding part at the time of the secondary molding. Can be prevented beforehand, and a good quality product can be easily and smoothly injection-molded.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention.
FIG. 1 is a perspective view showing an example of a cassette half, FIG. 2 is a sectional view showing an example of an injection mold, and FIG. 3 is a sectional view of a valve gate portion. 1 ... Transparent part (secondary molding part), 2,3 ... Colored part (primary molding part), 4 ... Connecting part (primary molding part), 6 ... Submarine gate mark, 7 ... Valve gate mark, 15: Valve gate (resin injection port), C: Cassette half.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinobu Takeda 3-1, Koganecho, Niigata City, Niigata Pref. Niigata Works, Mitsubishi Metals (56) References Japanese Utility Model No. 3-90921 (JP, U)

Claims (1)

(57) [Claims] 1. A multicolor molded article injection-molded by sequentially injecting a plurality of molten resins into a cavity formed in a mold, comprising: a primary molded part; and a secondary molded part surrounded by the primary molded part. A multi-color molded product comprising a secondary molding portion, wherein a gate trace by a valve gate is formed on the surface of the secondary molding portion, and the gate trace by the valve gate has a different shape.