JPH0545410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a synthetic resin molding that is applied to integrally resin mold an end cap to the end of a molding body.

BACKGROUND TECHNOLOGY In general, in synthetic resin moldings for vehicles, a long molding body M as shown in FIG.
An end cap E is integrally molded with resin at the end of the end cap.

To form this end cap E, a molding material having a bottom surface that matches the surface to which it is attached, such as an automobile body panel, and a desired outer surface shape is made of synthetic resin into a predetermined cross-sectional shape. After extrusion molding and cutting the molding material to a predetermined length to form a molding body, the end portion of this molding body is placed in the mold of an injection molding mold, and the molten resin is poured into the cavity space. Injection molding is carried out by injection.

Normally, when the molding material is extruded, it is inevitable that there will be variations of about ±0.3 mm with respect to a predetermined cross-sectional dimension depending on each production lot. Therefore, when the end portion of the molding body M obtained by cutting the molding material to a predetermined length is placed in the mold of the injection molding mold, the inner surface of the cavity and the outer surface of the molding body M A gap is created between the molding body and the molten resin injected into the cavity space in the mold leaks to the outside surface of the molding body through the gap, causing burrs to be generated on the outside surface of the molding body. There is.

In order to prevent the occurrence of burrs, conventionally, as shown in FIG.
is equipped with a push-up plate 13 supported by a compression spring 12, and the push-up plate 13 pushes up the outer surface of the molding body M from the bottom side so as to press it against the inner surface of the cavity mold 14, and then melts the molding body M. Cavity space 1 for resin
The injection is carried out at 5.

However, in this method of manufacturing a synthetic resin molding, the molding body M, which has a relatively large wall thickness, is simply pushed up in a single direction from the bottom side using the push-up plate 13 by the compression spring 12. Therefore, as shown in FIG. 8, gaps tend to remain on the outer surface of the molding body M, especially on the side sides of the outer surface, and the occurrence of burrs cannot be completely prevented.

Problems to be Solved by the Invention The present invention solves the problem by pushing up the molding body from the bottom side with a pressing material in the same way as described above.
The outer surface of the molding body and the inner surface of the cavity of the injection molding die are brought into closer contact with each other, and the molten resin is injected without any gaps. An object of the present invention is to provide a method for manufacturing a synthetic resin molding that is improved so as to form a molding made of synthetic resin.

Means for Solving the Problems In the method for manufacturing a synthetic resin molding according to the present invention, a longitudinal end portion of a molding body extruded from a synthetic resin so as to have an outer surface and a bottom surface has a resin on the bottom surface side. An injection molding mold is used to form a concave part by partially removing a part of the molding body to leave the outer surface side, and to integrally form an end cap at the end part in the longitudinal direction of the molding body. a pressing member that protrudes from the mold surface and is fitted into the recess of the molding main body, the pressing member is an elastic member having rubber-like elasticity, and the pressing member is fitted into the recess of the molding main body. After placing the longitudinal end portion of the molding body in which the recess is formed in the molding die, the in-die extension is Clamping the mold, at this time, the pressing material is compressed in the mold clamping direction, and its elastic repulsive force presses the recessed part of the molding body in the mold clamping direction, pressing it against the mold surface of the injection molding mold, The molding body is elastically deformed and expanded in the recessed portion of the molding body in a direction crossing the mold clamping direction, so that the outer surface of the molding body at the corresponding position of the pressing member is pressed against the mold surface of the injection molding mold, In this state, molten resin is injected into the cavity space to integrally form an end cap at the end of the molding body.

Function: In this method of manufacturing a synthetic resin molding, a concave portion is formed in the longitudinal end portion of the molding body by partially removing the resin portion on the bottom side, leaving the outer surface side thin, and further, When the longitudinal end portion of the molding body including this concave portion is placed in the mold of an injection molding die and the mold is clamped, a rubber-like elastic material protrudes from the mold surface of the mold located on the bottom surface side within the concave portion. In order to press the pressing member of the elastic member having a It can be pressed or pressed. In particular, when the pressing material is compressed in the mold-clamping direction, its elastic repulsive force presses the recesses of the molding body in the mold-clamping direction and against the mold surface. Since the molding body is elastically deformed and expanded in the intersecting directions, the entire outer surface side corresponding to the concave portion of the molding body can be brought into close contact with the mold surface of the injection molding mold, and there is a gap between the outer surface of the molding body and the molding body. There will be no gaps. Since the end cap is integrally formed by injecting the molten resin into the cavity space in this state, the molten resin is prevented from leaking to the outside surface of the molding body, and burrs are formed on the outside surface of the molding body. can be prevented from occurring.

Embodiments The following description will be made with reference to FIGS. 1 to 5.

The molding body M used in the molding is made by embedding a core material C such as aluminum foil inside and continuously extruding it as a molding material having a predetermined cross-sectional shape surrounded by the outer surface and the bottom surface. It is manufactured by cutting into long pieces of predetermined length.

Prior to placing the end portions of the molding main body M into the injection molding molds 1 and 2, the resin portion of the molding main body M is partially removed from the bottom surface _m1 of the longitudinal end portions of the molding main body M. A concave portion F is provided at an arbitrary length by selectively removing the terminal to reduce the wall thickness of the terminal while leaving the outer surface portion.
The cross-sectional shape of the bottom side of the recessed portion F is preferably formed to be similar and somewhat smaller than the cross-sectional shape of the outer surface m ₂ of the molding body M. This can be easily formed, for example, by using a cutter 3 or the like having the same tooth profile as the desired shape. When forming the recess F, it is preferable to also cut out the core material C of the molding body M. If the resin part of the molding body M shrinks due to cutting of the core material C, the core material C
Even if the molding body M protrudes in the direction of the end cap E in a similar manner, the end of the core material C does not hit the end cap E, and the molding body M and the end cap E come apart due to the end cap E being pushed apart. The occurrence of can be suppressed.

The injection molding mold on which the longitudinal end portion of the molding main body M is placed has a core mold 1.
The recess F of the molding body M is projected from the inner surface of the molding body M toward the opposing surface of the cavity mold 2.
An elastic member 4 fitted therein is attached as a pressing member. The elastic member 4 is preferably made of a material with high elasticity, flexibility, and resilience such as polyurethane resin, and the upper end surface of the molding body M that is fitted into the recess F of the molding body M is It has a similar shape that is somewhat larger than the inner surface shape in the cross-sectional direction of the recess F, and the longitudinal end portion of the molding main body M is large enough to leave some space with respect to the inner surface of the cavity space 5 of the cavity mold 2 on which it is placed. Preferably one that stands up. Further, this elastic member 4 is supported from behind by a presser plate 6 which is protruded with a relatively smaller rise than the rise of the elastic member 4, and the elastic member 4 is supported by the presser plate 6 in the longitudinal direction of the molding main body M. It is preferable to attach the molding body M so that the elastic member 4 is not greatly deformed and the elastic force due to the compressive deformation of the elastic member 4 is concentrated toward the outer surface of the molding body M.

When using this injection molding mold, when placing the longitudinal end portion of the molding body M inside the core mold 1 and the cavity mold 2, the bottom surface of the molding body M is
After fitting the elastic member 4 into the recess F of _m1 , the core mold 1 and the cavity mold 2 are clamped. Along with this, the elastic member 4 is inserted into the recess F of the molding main body M.
By compression-fitting the elastic members 4, the elastic member 4 is compressed in the mold-clamping direction, and is elastically deformed and expanded in the direction intersecting the mold-clamping direction within the recess F of the molding main body M, so that the elastic member 4 is compressed into the inner surface of the recess F. Pressed. When this elastic member 4 is pressed, the pressing force generated by the elastic member 4 acts radially on the inner surface of the recess F as shown by the arrow in FIG. By pushing it out toward the mold surface of the cavity mold 2, it is possible to prevent a gap from forming between the outer surface _m2 and the mold surface of the cavity mold 2. The outer surface of this molding body M is m ₂
If the molten resin is injected into the cavity space 5 while being pressed against the mold surface of the cavity mold 2, the molten resin leaks between the outer surface _m2 of the molding body M and the mold surface of the cavity mold 2. Since there is no burr on the outer surface _m2 , it is possible to suppress the occurrence of burrs.

Note that when molten resin is injected into the cavity space 5, the molten resin also comes into contact with the elastic member 4, but in this case, even if the elastic member 4 is a porous material, it will harden due to compression. Because of this, the molten resin does not penetrate into the elastic member 4, and when the mold is opened after the resin hardens, the elastic member 4 is released from the compressed state and at the same time an areal expansion force acts, so that the mold with the end cap E is formed. The molding main body M can be easily removed from the mold.

Effects of the Invention As described above, according to the method for manufacturing a synthetic resin molding according to the present invention, even if there is variation in the outer surface shape of the molding body, the molding body can be placed in the mold of the injection molding mold. This prevents gaps from forming between the outer surface of the molding body and the mold surface of the cavity mold on the end side in the longitudinal direction of the molding body, so that burrs caused by resin molding of the end cap are prevented from forming on the outer surface of the molding body. This makes it possible to produce synthetic resin moldings with good decorative surfaces.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method for manufacturing a synthetic resin molding according to the present invention, FIG. 2 is a partial perspective view of a molding body used in the same method, and FIG.
The figure is an explanatory diagram of the step of forming a recess on the bottom surface of the molding body in the process of the same method, Figure 4 is a partial perspective view of the molding body with the recess formed by the same method, and Figure 5 is the same method. Fig. 6 is a partial perspective view of a synthetic resin molding according to a general example, and Fig. 7 forms an end cap of a conventional synthetic resin molding. FIG. 8 is an explanatory diagram of the injection molding die, and is an explanatory diagram showing a problem in end cap molding using the injection molding die. M: Molding body, E: End cap, m ₁ : Bottom of molding body, m ₂ : Outer surface of molding body, F: Recess, 1: Core mold, 2: Cavity mold, 4: Pressing material (elastic Element),
5: Cavity space.

Claims (1)

[Claims] 1. A recess is formed in the longitudinal end portion of the molding main body, which is extruded from a synthetic resin so as to have an outer surface and a bottom surface, by partially removing the resin portion on the bottom surface side and leaving the outer surface side. An injection molding die that integrally forms an end cap at the end portion in the longitudinal direction of the molding body has a pressing member that protrudes from the mold surface located on the bottom side of the molding body and is fitted into the recess of the molding body. The pressing member is an elastic member having rubber-like elasticity, and the portion of the molding main body that is fitted into the recess has a shape that is substantially similar to the inner surface shape in a cross section of the recess. , after placing the longitudinal end portion of the molding body in which the recess is formed in the mold of an injection molding mold, the molding mold is clamped, and at this time, the pressing material is compressed in the mold clamping direction. The elastic repulsive force presses the recess of the molding main body in the mold clamping direction and presses it against the mold surface of the injection molding mold, and at the same time, the molding main body is elastically deformed in the direction intersecting the mold clamping direction within the recess of the molding main body. The outer surface of the molding body at the corresponding position of the pressing material is pressed against the mold surface of the injection molding mold, and in this state, the molten resin is injected into the cavity space to the end of the molding body. A method for manufacturing a synthetic resin molding, characterized in that an end cap is integrally formed.