JPS6116843A - Molding method of terminal section of molding made of synthetic resin - Google Patents

Abstract

PURPOSE:To obtain a smooth surface hardly having sink marks by integrally forming an end cap extending in the longitudinal direction of a molding proper while covering the outer surface of an end-cap core material from the cutting end of the molding proper. CONSTITUTION:When the end section of a molding proper 1 to which an end-cap core material 2 is fitted is fixed onto a bottom force 6 and top and bottom forces 5, 6 are fast stuck, a hold-down mold surface in the top force 5 is fast stuck to the outer surface of the molding proper 1, and a predetermined clearance is shaped between a molding die surface 52 and the end-cap core material 2. When an injection molding material is injected from a gate 7, an end cap 3 having a prescribed shape is formed at the end section of the molding proper, and the end cap is solidified under the state in which it is unified with the end- cap core material 2. Accordingly, the terminal section of the molding shape in this manner is finished in a smooth surface hardly having sink marks by the presence of the end-cap core material 2.

Description

[Detailed Description of the Invention] Synthetic resin moldings, which are made by extruding synthetic resin and cutting a bar with a constant cross-section into the required length, are often used for moldings used for the exterior of automobiles. . The cut ends of such synthetic resin moldings must be appropriately treated to maintain their aesthetic appearance.

This invention relates to a method of forming a synthetic resin molding in which the cut end is provided with an end cap formed by an improved means.

As a conventional end treatment means for synthetic resin moldings, it has been common to attach a separately manufactured end cap to the cut end of a molding body obtained by cutting a rod-shaped molding material.

Synthetic resin moldings effectively absorb external shocks and serve as a shock absorber.In addition, moldings are designed to prevent deformation due to aging and to help reduce weight and save materials. It is also possible to provide a hollow part or a recessed part (often a combination of both).
When the end cap is formed by injection molding on such a product, the injection molding material irregularly flows into the hollow part or the opening of the recessed part of the molding.

In order to prevent leakage, special closing means must be taken for the opening, which is difficult to put into practice.

In addition, when attaching a separate end cap to the cut end using the hollow part of the molding body, the connection part between the outer circumferential surface of the molding body and the outer circumferential surface of the end cap may not match, causing problems such as spoiling the appearance. There is a simple drawback.

In this applicant company, when the molding is a solid rod, the cut end thereof is inserted into an injection mold and the entire end portion (end cap portion) is injection molded directly onto the end portion. We also conducted tests and research on the method, but when the end part formed by injection molding becomes thick, shrinkage occurs due to shrinkage when cooling after molding, making it difficult to obtain a desirable surface. I also learned that.

The present invention provides a means for easily applying an end cap to a cut end of a synthetic resin molding by injection molding by making full use of the features of both of the above-mentioned means.

The molding made according to this invention is mainly the body side protector molding P1 shown in FIG.
It is used for front bumper guard, molding FB, IJ back bumper guard, molding RB, etc. End caps 3 are attached at both ends of the molding.
(Fig. 2) is installed. Reference numeral 4 denotes a mounting bracket for mounting the molding.

The molding body 1 is made by cutting a molding material extruded into an infinitely long rod-like body having a hollow part 11 and a recessed part 12 in the body by extrusion molding of synthetic resin, as illustrated in FIG. The end face marked with numeral 13
The main body 1 shown in the figure has an upper surface 15 with four stripes 14 formed in a flat surface, and a cross section of approximately trapezoid along with the upper surface. It consists of both sides 16.16 making up.

In the hollow portion 11, protruding stripes 17 are formed corresponding to the four stripes 14. Reference numeral 18 denotes a metal reinforcing material that is integrally extruded into the recessed notch 12 during extrusion molding of the main body.

In the present invention, a small end cap core material 2 is first attached to the cut end of the molding body 1.

As shown in FIGS. 3 and 3a, the end cap core 2 has a protrusion 23 on the main body 210 and the main body abutting surface 22, which has a cross-sectional shape corresponding to the cross-sectional shape of the hollow part 11 of the molding main body 1. , this protrusion 23 is located in the nuclear hollow part 11
are fixedly coupled with a tight fit.

Reference numeral 24 indicates four stripes corresponding to the protrusions 17 in the hollow portion 11. By press-fitting the protrusion 23 into the hollow portion 11 of the cut end of the main body, the end core material 2 is very easily fixed to the cut end of the main body as shown in FIG. Heartwood body 2
The external shape of end cap 1 is smaller than end cap 3. The core main body 21 of the embodiment has an upper surface 25, both side surfaces 26, and end surfaces 27 each having a similar external shape to that of the end cap 3, which is proportionally reduced in size.

When the end cap core is attached to the cut end of the molding body 1, the bottom surface 28 of the core body 21 also creates a suitable gap with the extension of the bottom surface of the molding body. However, the main body abutting surface 22 of the core body comes into close contact with the end surface 13 of the molding main body and seals the opening surface of the recessed cutout 12 .

In addition, if you want the molding to be equipped with stud bolts or other mounting fittings 4 for attaching it to the car body, you can insert them as an insert part when manufacturing this end cap core material by injection molding or the like. It is advantageous to put

Next, at the cut end of the molding body 1 to which the end cap core material 2 is attached, an end cap 3 having a regular external shape is formed thereon by injection molding, using the core material 2 as a center.

The end cap 3 is formed as follows.

In FIG. 5, 5 is the upper mold of the end cap injection molding die, 6 is the lower mold, and the lower surface of the upper mold 5 has a presser mold surface 51 that tightly fits the upper surface 15 and both side surfaces 16 of the molding body. and a mold part 52 for forming the outer shape of the end middle yap are formed by four people. Presser mold surface 51 and mold part 5
It goes without saying that the boundary with 2 is connected by a smooth surface unless there is a special design. Reference numeral 53 indicates a protrusion that fits into a part of the groove 14 of the molding body 1. The lower mold 6 is shown as having a mounting fitting (socket bolt) 4 on its main body like the end cap core 2 of the embodiment, and the upper surface of the lower mold is provided with a mounting bracket that the end cap core has. It has a receptacle 61 for receiving the metal fitting 4. As is clear from the size of the end cap core 2, when the mounting bracket 4 is fitted into the receptacle 61 and the end of the molding body 1 with the end cap core 2 attached is placed on the lower mold 6, the end cap A gap 60 is created between the bottom surface 28 of the core material 2 and the upper surface of the lower mold, but the receiving 6
Injection molding material can be easily prevented from flowing into the receiving hole 61 by, for example, forming an annular ridge 62 corresponding to the height of the gap 60 on the first opening surface. The lower part of the concave notch 12 of the molding body 1 also communicates with the injection mold through the same gap 60, but either a convex part 63 that fits tightly into the concave notch 12 is provided on the upper surface of the lower mold in this part, or an end cap molding is performed. The communication port can be closed by placing the mold surface in a protruding manner so as to create a similar recess on the bottom surface of the end cap 3. 7.7 shows a groove forming a gate for injection molding material.

As shown in FIG. 5, when the end of the molding main body 1 with the end cap core material 2 attached is placed on the lower mold 6 and the upper and lower molds 5.6 are brought into close contact with each other, the presser surface of the upper mold 5 is pressed against the molding surface. It tightly presses the outer surface of the main body 1 and forms a predetermined gap between the mold surface 52 and the end cap core material 2. In this case, the receptacle 61 serves to position the molding edge.

When the injection molding material is injected through the gate 7, an end cap 3 having a predetermined shape is formed at the end of the molding body, and this end cap is solidified while being integrated with the end cap core 2.

The openings of the hollow part 11 and the recessed part 12 which are open in the end face of the molding body are completely closed by the installation of the end cap core material 2 and the mold without the need for any other means. injection molding is performed,
Molding material will not flow into unnecessary areas. It goes without saying that the material for the end cap core material 2 should be selected to be hard enough not to be easily deformed by the injection pressure of the synthetic resin material when molding the end cap 3.

In the above embodiment, the molding body has both a hollow part and a recessed part, so the case where the protruding part of the end cap core material is press-fitted into the hollow part was explained as an example. When only a concave notch is provided, the end cap core may be provided with a protrusion 23 that tightly fits into the appropriate position of the concave notch.

The molding terminal portion formed as described above is
The presence of the end cap core material 2 creates a smooth surface with almost no sink marks, and the connection between the molding body and the end cap 3 is extremely smooth, unlike when the entire molding is molded as one piece. There is no effect of giving an unnatural appearance, and moreover, the formation of the end-middle layer has the effect that the entire process can be completed in a few very simple steps. In addition, when installing a molding with a mounting bracket, there is an advantage that the molding with the mounting bracket can be manufactured without any other effort by attaching it to the metal A4 end cap core material in advance. .

Note that the end cap core material and the end cap may be made of the same synthetic resin material, but if the end cap core material has an external shape that is similar to that of the end cap, the wall thickness of each part of the end cap may be t't is uniform, a stable end cap can be obtained, and when an especially expensive material is used only for the end cap, the amount of the expensive material used can be kept to a minimum. can be done.

A brief explanation of the Buddhist altar surface. Figs. 1(a) and 1(b) are perspective views showing where the molding made according to the present invention is used in an automobile, and Fig. 2 is a side view of the end portion of the molding according to the present invention.
Fig. 3 is a perspective view of the cut end of the molding body and the end cap core attached to it, Fig. 3a is a perspective view of the core seen from a different direction, and Fig. 4 shows how the end cap core is attached to the end of the molding later. The side view, FIG. 5, and FIG. 6 are cross-sectional views of the injection mold showing a state in which a molding end is positioned and a state in which an end cap is molded, respectively.

1... Molding body 200. end cap heartwood 3... End cap

Claims (1)

[Claims] A step of molding a long molding material having a constant cross-sectional shape by extrusion molding of a synthetic resin material, a step of cutting the molding material into a predetermined length to obtain a molding body, and a step of cutting a final molding material at the cut end of the molding body. arranging a separately manufactured end cap core material having an outer diameter smaller than the outer diameter of the end cap formed by the molding body, and placing the end of the molding body in an injection mold consisting of an upper mold and a lower mold; , an injection molding material is injected into the space formed when the upper mold and the lower mold are closed, and an end cap extending in the longitudinal direction of the molding body is integrated, covering the outer surface of the end cap core material from the cut end of the molding body. A method for forming an end portion of a synthetic resin molding, which comprises a step of forming a synthetic resin molding.