JPS6347454Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a core used for molding the connecting part of annular products with hollow parts such as weather strips, which consists of a bullet-shaped core body and a bent rod-shaped handle. Regarding. Here, we will explain an example in which a weather strip (hereinafter abbreviated as W/S) having the cross section shown in FIG. The scope of application is not limited to W/S. In FIG. 1, 2 is a hollow seal made of sponge rubber, and 3 is a U-shaped grip made of solid rubber in which an insert 4 is embedded. Usually, the connecting portion 2 is molded using a mold 5 as shown in FIG. That is, after inserting and fixing both ends of the W/S extrudate W from both sides into the cavity 6 formed in the mold and having the same cross section as the external cross section shown in FIG. 1 (see FIG. 4), the core 7 is W/S via child removal hole 8
It is inserted into the hollow seal portion 2 of the extrudate and set at a predetermined position in the mold 5 (see FIG. 5). Here, the middle child 7 is
It consists of a bullet-shaped core body 7a and a bent rod-shaped handle 7b for setting and removing the core. Next, rubber material (solid) is injected or injected into the cavity formed in the cavity 6 through the sprue 9 and after vulcanization is completed, the mold is opened and the core 7 is inserted through the hollow seal portion 2 through the core extraction hole 8. Then take it out. At this time, the temperature of the core (usually both the main body and the handle are made of metal such as iron) has risen to near the vulcanization temperature (usually around 200°C), so the core extraction hole 8 is inserted into the core body 7.
When subjected to the expansion action at step a, the rubber material around the hole gets heated and its strength decreases, making the hole more likely to tear. For this reason, although it is desired to reduce the diameter of the core punching hole mainly from the viewpoint of product appearance, it has not been possible to make the diameter of the core punching hole very small (usually the diameter is approximately the same as the core body). ). This trend is based on EPDM
This is noticeable in the case of rubber materials such as rubber materials, which have a large decrease in strength at high temperatures. In view of the above, the object of this invention is to provide a core for forming a connecting portion of an annular product, which allows the diameter of the core punching hole to be smaller than that of the conventional core. The core for forming the connection part of an annular product of this invention achieves this purpose by forming the core body from a heat-resistant synthetic resin material. This idea will be explained in detail below. As shown in FIG. 5, in the core 7 consisting of a core body 7a and a handle 7b, the core body 7a is made of a heat-resistant synthetic resin material. At this time, examples of heat-resistant synthetic resin materials include fluororesins, polyamide resins, and phenolic resins. Also, the handle 7
The material of b is not particularly limited, but from the viewpoint of rigidity etc., it is made of metal such as iron as in the past. This core 7 is
Usually, it is obtained by integrally molding the handle as an insert by injection or the like. The method of forming the connection part 1 of the W/S using the core 7 is the same as the conventional method, but when the core is extracted after vulcanization molding, the diameter of the core extraction hole is Even if it is considerably smaller than before, it is difficult for holes to break when removing the core. The reason for this is not clear, but since the core body is made of synthetic resin, the heat transfer resistance in the boundary film is much higher than that of metal materials, and even if the core body comes into contact with the hole edge, the hole It is presumed that this is because the rubber member on the edge is less susceptible to the heat effect. Table 1 shows the results of the hole breakage rate when the connecting portion was molded using a W/S having a core punching hole of each diameter and core punching was performed 50 times each. The diameter of the core body is 11φ in both cases, and the rubber material of the W/S is FPDM. Additionally, during testing, it was necessary to apply silicone oil every time the core body was made of iron to improve the slippage of the core body, but for the core body made of PTFE (fluoroplastic), it was necessary to apply silicone oil each time. was unnecessary. As described above, in the core for forming the connection part of an annular product of this invention, even if the diameter of the core punching hole is considerably smaller than that of the conventional core, the hole is not easily torn when the core is punched out. 【table】

[Brief explanation of drawings]

Fig. 1 is an enlarged sectional view of the W/S to which this invention is applied in Fig. 2, Fig. 2 is a plan view of the annular W/S, and Fig. 3 is the mold used for forming the connection part in Fig. 2. Fig. 4 is a perspective view showing both ends of the W/S extrudate inserted into the mold shown in Fig. 3, and Fig. 5 shows a state in which the core is set in the mold for connection molding. FIG. 1...Connection part, 2...Hollow seal part (hollow part),
5... Mold, 6... Cavity, 7... Inside, 7a... Core body, 7b... Handle, 8... Core extraction hole, W...
...W/S extrudate.

Claims (1)

[Claims for Utility Model Registration] A core used for molding a connecting part of an annular product with a hollow part such as a weather strip, which consists of a bullet-shaped core body and a bent rod-shaped handle, A core for forming a connection part of an annular product, characterized in that the core body is made of a heat-resistant synthetic resin material.