JPH0667578B2 - Multicolor molded structure - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to multicolor molding, and relates to a multicolor molding structure molded with resin materials having different melting temperatures (injection temperatures).

[Description of Prior Art]

It is known to perform a two-color molding process or a multi-color molding process using a polycarbonate resin or an A / B / S resin. In the molding process for performing the above-mentioned multicolor molding process, the injection temperature is different, especially when the injection temperature is low and the fluidity of the injected material is high, the injected material penetrates between the fixed mold plate and the movable mold plate of the mold. Burrs are generated between the primary molded product and the secondary molded product and in the corners of the secondary molded product.

Further, in the case of multicolor molding, a problem of material shrinkage due to primary molding occurs. This point will be described with reference to FIG. In FIG. 7, 1 is a fixed side mold plate, 2 is a movable side mold plate, 4 is a cavity, 6 is a primary molded product, and PL is a parting line of the fixed part 1 and the movable part 2.

When the primary molded product 6 has a shape as shown in the figure and the X dimension in the cavity 4 is large, the cap 8 is generated due to the molding shrinkage of the primary molded product 6. For example, if the X dimension is 30 mm and the primary molded product is glass fiber reinforced PC molding shrinkage of 0.3%, the gap 8 is 0.09 mm. If a thermoplastic elastomer such as urethane, which is a secondary molding material, is injected in this state, it will flow into the gear 8 due to its high fluidity, resulting in an end burr. In this state, the gear tape 8 is very thin, so the primary molded product 6
The adhesive effect of the elastomer on the can not be expected, and it becomes very unsightly when it is used as an external part because it becomes a wave-like separated state. On the contrary, if the thickness of the gear 8 is to be increased, this is determined by the shape and material of the molded product, and the elastomer cannot be positively twisted thickly. Also, it is difficult to treat with a mold because it becomes an undercut.

[Means for solving problems]

The present invention has an object to solve the above-mentioned problems, and a side wall portion along a cavity inner wall of a mold forming a multicolor molding structure is provided at one end of a primary molding body made of a first resin material, and After inserting the primary molded body into the mold, a second resin material is injected, and the wall portion is pressed against the inner wall of the cavity by the second resin material to press the wall portion and the inner wall of the cavity. We propose a multicolor molded structure characterized by being molded so as to close the gap between the and.

FIG. 1 is a diagram showing a first embodiment of the present invention.

The fixed-side template and the movable-side template configuration are the same as in FIG. The movable mold plate 2 has a protrusion 2a extending along the end surface 6a of the primary molded product 6. In the primary side molding, a wall portion 6b extending from the end surface 6a of the primary molded product 6 along the protrusion 2a of the movable mold plate 2 and the protrusion 2a from the end of the wall portion 6b. Processing is performed so as to form a bent portion 6c that is bent at a substantially right angle.

FIG. 1 shows the shape of the thermoplastic resin 6 on the secondary side after molding shrinkage, in which gears 10 and 12 are generated. The height of the protrusion 2a is larger than the molding shrinkage amount of the thermoplastic resin 6, and a part of the vertical end face 6c bent from one end of the wall portion 6b is located on the protrusion 2a of the movable side template 4. It is in close contact. FIG. 2 shows a state in which the thermoplastic elastomer 14 made of a soft material such as urethane is injected into the cavity in this state.

Thermoplastic resin 6 due to injection pressure of thermoplastic elastomer 14
The horizontal end surface 6d of the wall portion 6b is subjected to a force in the direction of the arrow and elastically deformed as shown in FIG. 2, and the horizontal end surface 6e of the bent portion 6c comes into close contact with the movable side mold plate 2. Further, the vertical end face 6f also remains in close contact only by sliding on the side wall of the protrusion 2a.

With the above structure, the gear tape 12 prevents the inflow of the completely blocked elastomer 14 when the thermoplastic elastomer 14 is injected. This makes it possible to prevent the occurrence of burrs shown in the conventional example. Further, considering various molding conditions, even if a small amount of elastomer may flow into the above-mentioned location, the vertical end face is in close contact with the side wall of the protrusion 2a, so that the burr does not further advance. In consideration of the above, the Y dimension is close to the molding limit of the thermoplastic resin 12, for example 0.3 mm.
It is desirable to make it as small as possible to make the burr under the worst conditions inconspicuous.

FIG. 3 shows an embodiment in which the two-color molded cover according to this embodiment is used for a grip of a camera.

The front cover part of the grip, which is formed by two-color molding of the thermoplastic resin 18 and the thermoplastic elastomer 17, is attached to the grip body 19 and the reinforcing plate 20.
It is also tightened with screws. It can be attached and detached by a tightening screw receiver 22 and a tightening screw 21 on the camera body side. twenty three
Is a side cover, 24 is an upper lid, 25 is a back lid, 26 is an aft lid, and 27 is a battery storage chamber. With this structure, the removable grip also serves as the battery lid. Here, the end face
17a and 18a are portions exposed to the outside when the grip is removed. If the conventional example is left as it is, it is very unsightly because burrs of the thermoplastic elastomer 17 are generated. By doing so, burr is surely prevented.

Also, regarding the mating parts 17b, 19a, it seems that there is no problem in particular because it is a vertical burr that can be seen in the back, but if it is the conventional example, the burr of the elastomer 17 will be separated and it will become a wavy shape and interfere with the part itself However, it is undesirable and it is desirable to take a burr countermeasure based on the embodiment of the present invention because it is visually unobservable through the gap.

FIG. 4 shows another embodiment of the present invention. The shape of the protrusion 30a of the movable side mold plate 30 is different from the example of FIG. The horizontal end face 28a is adhered to the movable side mold plate 30 by the injection pressure of the thermoplastic elastomer 29 to prevent the burrs of the elastomer 29 from being the same as in the above-mentioned embodiment, but there are two vertical end faces 28b and 28c. ,
In addition to the above-described embodiment, a safety structure with a loop for preventing burr is adopted. However, the main purpose of this shape is to extend the shape of the thermoplastic resin as a molded product from the end surface of the elastomer as a single paragraph as shown in FIG. Like the embodiment, it is processed as a groove having vertical end faces 28b, 28c to make the appearance look more beautiful.

FIG. 5 shows another embodiment in which the movable side mold plate 33 has no protrusion. This is an example in the case where it is not desirable to provide a stepped portion, a groove portion or the like as shown in FIGS. 2 and 4 on the end surface of the thermoplastic resin 31 for the sake of appearance. In this case, the injection pressure of the thermoplastic elastomer 32 causes the horizontal end surface 31a of the thermoplastic resin to be drawn.
It is necessary to set the conditions so that the slab will surely adhere to the movable side mold plate 33.

FIG. 6 shows another embodiment, that is, an example in which a flange portion for promoting elastic deformation of the thermoplastic resin 34 due to the injection pressure of the thermoplastic elastomer 35 cannot be provided. Movable side template
The side wall of the projection 36a of 36 and the vertical end surface 34a of the thermoplastic resin 34 are in close contact with each other even after molding shrinkage. When the thermoplastic elastomer 35 is injected in this state, the elastomer enters the gear gap formed by the molding shrinkage of 34, and the burr 35a is generated. However, because of the action of the vertical end face 34a described above, no further progress is made. Therefore, as described with reference to FIG. 4, by taking a small z dimension close to the molding limit of the thermoplastic resin 34, the burr is made inconspicuous as much as possible. Is something that can be done. As described above, the elastomer does not enter the gear 37.

As described above, the side wall portion 6b along the inner wall of the mold cavity is formed at one end of the primary molded body 6 of the thermoplastic resin material, and after the primary molded body is put into the cavity, it is placed in the cavity. The second resin is injected, and the wall portion 6b of the primary molded body is pressed against the inner wall of the cavity by the injected second resin material to close the gap between the wall and the inner wall of the cavity. By doing so, it was possible to prevent the resin material from wrapping around, and to prevent the occurrence of resin burrs. Further, by providing the bent portion 6c on the wall portion 6b, the horizontal end portion 6e and the vertical end portion 6f of the bent portion can reliably prevent the second resin material from wrapping around.

[Brief description of drawings]

1 and 2 are sectional views of a mold structure showing a first embodiment of the present invention. 3A and 3B show perspective views of the multicolor molding structure according to the present invention. 4, 5, and 6 are sectional views of the mold structure of another embodiment according to the present invention. FIG. 7 shows an explanatory diagram related to the prior art. 1 …… Fixed side template 2 …… Movable side template 6,28,31,34 …… Primary molded product 14,29,32,35 …… Secondary molded product

Claims (2)

[Claims] 1. A multicolor molding structure produced by injecting a first resin material and a second resin material into a cavity of a mold for molding a molded article, the primary molding body being made of the first resin material. A wall portion along the cavity inner wall of the mold is formed at one end of the mold, and after the primary molded body is put into the cavity, the second resin is injected into the cavity and the second injected resin is injected. A multicolor molded structure characterized in that the resin material is used to press the wall portion of the primary molded body against the inner wall of the cavity to close the gap between the wall portion and the inner wall of the cavity. 2. The multicolor molded structure according to claim 1, wherein a bent portion is provided on a wall portion of the primary molded body.