JPS5949904B2 - Cap manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a double-layer cap consisting of a combination of an inner wall having chemical resistance and an outer wall made of a material with excellent printing and moldability. A frame-shaped inner wall with a smooth surface is preformed from a chemical-resistant material,
Then, the frame-shaped inner wall is inserted into the screw core of the mold (L), and a synthetic resin with excellent surface treatment and beautiful appearance is injected into the cavity provided around the frame-shaped inner wall to melt the resin. The frame-shaped inner wall is plastically deformed along the screw core by temperature and injection pressure, and a thread groove is formed, and the frame-shaped inner wall and the injection resin are integrally fused and welded, and an outer wall is formed on the outside of the inner wall. The present invention relates to a cap manufacturing method characterized by manufacturing a double cap by fitting and forming.

The caps of bottles for storing medicines, cosmetics, etc. had to be made of chemically resistant synthetic resin materials such as polyethylene, polypropylene, vinyl chloride, etc., or metals, rubber materials, etc. Materials generally have poor suitability for printing and molding, making it impossible to create beautiful, smart products with high commercial value.

Therefore, conventionally, in order to improve this drawback, the inner wall was molded from a chemical-resistant material, and the outer wall was separately molded from a synthetic resin with excellent printing and molding processability, such as AS resin, ABS resin, etc. A double cap was constructed by forcibly fitting the inner and outer walls of the cap using ribs, undercuts, etc., but this type of method poses the risk that the two may separate if a strong torque is applied to the cap. In addition, there were disadvantages such as the forced fitting work was difficult and it was difficult to construct a thin cap.

Also, recently, a method has been implemented in which two types of resin are injected separately from two sprues and the inner and outer walls are molded with the different resins at once, but in order to implement this method, It requires an expensive injection molding machine with a special structure, and although it is good when the inner and outer walls are molded with synthetic resin materials, it has disadvantages such as being impossible when using metal materials for the inner walls. It was hot.

The method according to the present invention relates to a completely new technique that fundamentally improves the drawbacks of the prior art.

To specifically explain one embodiment of the present invention with reference to the drawings, the first embodiment is as follows.
In Figures 4 to 4, 1 is a plug-shaped inner wall with a thin and smooth surface constructed by vacuum forming a polypropylene sheet, 2 is a cavity with a sprue 3 on the top, and 4 is a cavity. This is a screw core inserted into 2. In the present invention, as described above, the pre-formed thin plug-shaped inner wall 1 is attached around the screw core 4 and inserted into the cavity 2. After the screw core 4 and the cavity 2 are closed, the cavity 2 is closed. By injecting ABS resin from the sprue 3, the inner wall 1 is softened by the injection pressure and the melting temperature of the resin and plastically deformed around the screw core 4, and the thread groove 6 is formed. After the outer wall 5 of a constant thickness is fused and welded to the inner wall 1 around the inner wall 1 and the inner wall 1 and the outer wall 5 are integrally formed, the screw core 4 is extracted from the inner wall 1 to form a thread groove on the inner peripheral surface. A double cap with 6 can be molded.

In the above embodiment, the plug-shaped inner wall 1 with a smooth surface can be made of resins such as vinyl chloride, polyethylene, and polypropylene, which are highly resistant to chemicals, as well as metals such as aluminum, and its thickness is equal to that of the outer wall 5. The thickness may be as long as it can be deformed depending on the injection pressure and temperature of the resin injected.
A range of 0 micron to 1.0 mm is preferred.

This inner wall 1 can be formed by vacuum forming, injection molding, press molding, or the like. As the material for the outer wall 5 in the above embodiment for the nose, ABS resin, AS resin, polypropylene, etc., which have excellent workability and can be molded with a beautiful appearance, can be used, and the pressure during injection molding is 50 to 80 k9/CIR.
Also, the melt concentration is preferably 190 to 210°C.

As described above, the method according to the present invention involves forming a plug-shaped inner wall with a smooth surface from a chemical-resistant material in advance, and injecting a synthetic resin with excellent workability around it while attaching it to the screw core. The inner wall is plastically deformed by the temperature and pressure and brought into close contact with the screw core to automatically form a thread groove on the inner circumferential surface of the inner wall, and the outer circumferential surface of the inner wall is melted and welded with the injection resin. It is possible to automatically and easily manufacture a double cap in which the outer wall made of resin is fitted with a screw groove, and can be easily manufactured using a general injection molding machine without using a special injection molding machine as in the past. In addition, metal materials can be used in addition to synthetic resin as the inner wall material, and the finished product is constructed by integrally fusing the inner wall and the outer wall, and has a threaded groove. Since the two parts are fitted together, there is no risk of the outer wall peeling off from the inner wall during use, unlike conventional products, and the cap as a whole can be molded thinly, making it beautiful and stylish. be.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the inner wall, FIGS. 2 and 3 are explanatory diagrams showing the manufacturing process, and FIG. 4 is an explanatory diagram of the completed part. 1...Inner wall, 2...Cavity, 4
...Screw core, 5...Outer wall, 6...
...Screw groove.

Claims (1)

[Claims] 1. A plug-shaped inner wall with a smooth surface is molded in advance from a chemical-resistant material, the plug-shaped inner wall is inserted into a screw core of a mold, and a surface treatment is applied to the cavity provided around the plug-shaped inner wall. By injecting a synthetic resin with excellent properties and a beautiful appearance, the plug-shaped inner wall is plastically deformed along the screw core by the resin melting temperature and injection pressure, and a thread groove is formed, and the plug-shaped inner wall and injection A method for manufacturing a cap characterized by manufacturing a double cap by integrally fusing and welding resin and forming an outer wall on the outside of an inner wall.