JPH04270614A - Joining structure of synthetic resin hollow body - Google Patents

Abstract

PURPOSE:To prevent a deviation of confronting surfaces of half-split bodies due to contraction and a leak of joining resin through a space in the confronting surfaces in a two stage molding method, by a method wherein a hollow and protrusion which are positioned to each other are formed respectively in the confronting surfaces of the half-split bodies. CONSTITUTION:Protrusions 43 which are meshed with hollow parts 33, projected upward and possess a triangular section are formed in a longitudinal direction into confronting surfaces between flange parts 41, 42, fitted into mold surfaces at the time of curing of resin in the primary molding of the half-split bodies 3, 4 and confronting surfaces 30, 40 are prevented from falling into inward. Then under their confronting state, they are meshed with each other and the confronting surfaces 30, 40 are held at a fixed confronting position without having a deviation. Therefore, spaces 34, 44 of flanges 31, 41, which are confronted with each other, form a casting space R1 where it is damped up inwardly. Since the confronted surfaces abut almost completely against each other, it is eliminated that molten resin B is leaked through the space when the molten resin B is cast through the sprue and a hollow body product having a favorable external appearance is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining structure for producing a hollow body by abutting and joining injection molded half bodies.

0002

[Prior Art] Blow molding is a common method for manufacturing hollow containers, but due to the structural strength or shape of the hollow body, primary injection molding is performed on the divided halves. A two-stage molding method has been proposed in which the butted parts are joined by secondary injection molding of resin (Patent Publication No. 2).
-20410). However, in this type of two-stage molding, product shrinkage occurs when the half-split body of the primary injection molding hardens.
There is a problem in that the abutting end surfaces collapse inward within the cavity in the mold, making it difficult to perform a predetermined butt joint. There is also the problem that the molten resin injected into the void formed by the abutting end surfaces leaks out of the void and forms burrs.

0003

[Problem to be Solved by the Invention] Incidentally, the inward collapse of the abutting end surface due to product shrinkage can be resolved by providing an engaging portion with the mold on the outside of the abutting end surface and pulling it outward. , which requires cutting and polishing after molding. Furthermore, it is necessary to take measures to prevent the molten resin from leaking out of the cavity, which complicates the mold structure. Therefore, the present invention focuses on the fact that the leakage of the molten resin is also caused by the inward collapse of the abutting end faces, and aims to provide a joining structure that can simultaneously solve the above conventional problems. Take it as a challenge.

0004

[Means for Solving the Problems] The present invention involves injection-molding half bodies, abutting their end faces against each other in a mold, and then secondarily injecting a molten resin material for joining into the abutting portions to join them. In this structure, the joint structure of synthetic resin hollow bodies is characterized in that unevenness for positioning each other is formed along the longitudinal direction on the abutting surfaces of each half body.

[0005]

[Operation] According to the present invention, the joining end surface forms an uneven surface that mutually positions each other in the die cutting direction along the longitudinal direction, so that in the primary forming of the half body, each uneven part meshes with the mold and collides with the die. It is possible to prevent the end face from falling inward. In addition, when clamping the mold in secondary molding, the abutting end surfaces of the opposing half bodies are positioned by fitting the concave and convex portions into each other,
Since the cavity into which the molten resin is injected is prevented from deforming and the abutting end faces are completely sealed inward, leakage of the molten resin for joining can be prevented.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on specific examples shown in the accompanying drawings. FIG. 1 is a cross-sectional view showing the molded state of the joint structure of the present invention, showing the state before mold clamping for secondary molding after primary molding of each half of the hollow body. FIG. 2 is an enlarged perspective view of the main parts thereof, FIG. 3 is a sectional view showing a state in which molten resin is injected into the joint structure of the present invention after mold clamping for secondary molding, and FIG. 4 is an enlarged perspective view of the main parts. It is.

In the drawings, 1 is an upper mold, 2 is a lower mold, and hollow halves 3 and 4 are molded in each mold. The half body 3 has flanges 31 and 32 protruding outward from the periphery on the abutment surface 30 of the main body, and a recess 33 with a triangular cross section is formed in the abutment surface 30 extending in the longitudinal direction. At the same time, the outer lower surfaces of the flange portions 31 and 32 are cut out to form a cavity 34 extending in the longitudinal direction. On the other hand, the half body 4 also has outwardly protruding flange parts 41 and 42 on the peripheral edge of the main body part 40, and a convex part 43 with a triangular cross section that protrudes upward and engages with the above-mentioned concave part 33 on the abutting surface thereof. are formed in the longitudinal direction, and the outer lower surfaces of the flanges 41 and 42 are cut out to form a cavity 44 extending in the longitudinal direction.

The uneven portions 33 and 43 formed on the abutting surfaces engage with a mold surface (not shown) when the resin hardens in the primary molding of the half bodies 3 and 4, and the inner surfaces of the abutting surfaces 30, 40 engage with a mold surface (not shown). Prevent falling. Also, in their collision state,
As shown in FIG.
are held in a predetermined abutment position without shifting. Therefore, the flange portions 31 (32
) and 41 (42) spaces 34, 44 are the uneven portions 33,
34, an inwardly dammed injection cavity R1 is formed, and the abutting surfaces almost completely abut, so that when molten resin B is injected through the spool, it will not leak from the cavity R1. It disappears.

As shown in FIG. 5, the above-mentioned positioning unevenness and injection cavity are formed by half bodies 5 and 6 of a hollow body having a circular cross section.
If the end face is thick as shown in Figure 6,
The recesses 51, the protrusions 61 and the cavities 52, 62 can be formed directly on the abutment surfaces 50, 60. It is sufficient that these uneven parts can be positioned with respect to each other, and as shown in FIG.
3 may have a circular cross section. In addition, as shown in FIG.
A recess 64 may be formed in the abutting surface 60 on the half body 6 side, and in this case, the shape of the recess may be changed to a rectangular cross-section 65 (see FIG. 9). In short, the concavo-convex portions may have any shape as long as they fit into each other so as to be positionable.

0010

As is clear from the above description, according to the present invention, injection molded half bodies are abutted against each other in their end faces in a mold, and molten resin for joining is applied to the abutting portions. In the structure in which materials are bonded by secondary injection, the joint end surface has an uneven surface that positions each other in the die cutting direction along the longitudinal direction, so that each uneven part engages with the mold during the primary molding of the half body. This can prevent the abutting end surfaces from falling inward. In addition, when clamping the mold in secondary molding, the abutting end surfaces of the opposing half bodies fit into each other and are positioned,
The hollow space into which the molten resin is injected is prevented from deforming, and the abutting end faces are completely sealed inward, which prevents the molten resin for joining from leaking and provides a hollow body with a good appearance. A product can be formed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the molded state of the joint structure of the present invention;

[Figure 2] An enlarged perspective view of the main parts of Figure 1,

[Fig. 3] A cross-sectional view showing a state in which molten resin is injected into the joint structure of the present invention,

[Figure 4] An enlarged perspective view of the main parts of Figure 3,

[Fig. 5] A cross-sectional view when the first modification of the joining structure of the present invention is applied to another hollow body,

[Figure 6] Enlarged side view of the main part of Figure 5,

[Fig. 7] A cross-sectional view of a second modification of the joining structure of the present invention,

[Fig. 8] A cross-sectional view of a third modification of the joining structure of the present invention,

FIG. 9 is a sectional view of a fourth modification of the joining structure of the present invention.

[Explanation of symbols]

1 is an upper mold, 2 is a lower mold, 3 and 4 are hollow halves, 3
0 and 40 are abutment surfaces, 31 and 32 are flange parts, 33
41 and 42 are flange portions, 43 is a convex portion, and R1 is an injection cavity.

Claims (1)

[Claims] Claim 1: In a structure in which injection-molded halves are brought together by abutting their end surfaces against each other in a mold and a molten resin material for joining is secondarily injected into the abutting portions, each half is A joining structure of synthetic resin hollow bodies, characterized in that unevenness for mutual positioning is formed along the longitudinal direction on the abutting surfaces of the bodies.