JPS61177226A - Molding of cap - Google Patents

Abstract

PURPOSE:To obtain a cap, the mechanical strength of which is increased and the external appearance of which is made nice, by a method wherein a cylindrical movable mold for outside wall, on the peripheral surface of which a spiral groove is engraved, is arranged movably in both forward and backward directions with respect to a mold for outside wall, on the inner peripheral surface of which a stepped part is formed. CONSTITUTION:Air-pressure forming operation through the outer periphery of a jig 5, which advances downwards, is applied to a heated synthetic resin sheet 10, which is fixed to the open end of a mold 1 for outside wall, in order to form a bottomed short cylindrical molded part 19. After that, a topped short cylindrical form is made by retreating the jig 5 upwards under the state that the air-pressure forming operation continues to be applied and simultaneously advancing a movable mold 3 upwards to the neighborhood of the opening end of the mold 1. The lower end of the outside wall 11 is kept in a posture abutted against the molding surface of a stepped part 2. In addition, some portion of a bottom wall 12 gouges into a spiral groove 4 on the peripheral surface of the movable mold 3, resulting in forming a spiral bead 14 on an inside wall 13. A double cylindrical formed part 20 is made by screwing out the movable mold 3 and by cutting off the upper end of the outside wall 11 from the remaining part of the synthetic resin sheet 10.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for molding a double-cylindrical synthetic resin mold camp.

``Prior art'' Caps that are screwed onto the mouthpiece of containers are generally injection molded from synthetic resin, but since they must have high mechanical strength, they are inevitably thick, and therefore they are made from plastic. It has disadvantages in that it consumes a large amount of material, is heavy, and suffers from a so-called sink phenomenon, especially in thick parts, resulting in slight unevenness on the surface, resulting in poor appearance.

In order to overcome this drawback, for example, a method of cutting out the thickness of the thick portion has been considered, but this has the disadvantage that the molding die becomes complicated and the molding process is time-consuming.

"Problems to be Solved by the Invention" The present invention is a cap molding method developed to solve the above-mentioned conventional drawbacks and inconveniences, and is a method for forming a cap that is high in mechanical strength, lightweight, and has a good appearance. ``Means for solving the problems'' and ``effects'' The cap forming method of the present invention involves slightly reducing the inner diameter of the lower end of the cylindrical forming space. The outer wall mold 1 has a stepped portion 2 formed on its inner peripheral surface, has an outer diameter equal to the inner diameter of the lower end of the molding space of the outer wall mold 1, and has a screw groove 4 carved on its peripheral surface. This is carried out using a movable mold 3 which has a cylindrical shape and is arranged in the outside wall mold 1 so as to be able to move forward and backward.

First, the movable mold 3 is waiting in a retracted position where its flat upper surface is approximately at the same height as the stepped portion 2, and the heated synthetic resin sheet 10 is placed at the open end of the outside wall mold 1. A primary molded product 19 having a short cylindrical shape with a bottom is formed by fixing it to and performing pressure forming.

After that, the movable mold 3 is moved while continuing the air pressure molding operation.
is advanced to near the open end of the outer wall mold 1, the lower surface of the primary molded product 19 is inverted and stretched to form a crested short cylindrical body, and then the upper end of the primary molded product 19 is It is separated from the rest of the resin sheet 10 to form a double-cylindrical secondary molded product 20.

Furthermore, the cap 9 is formed by fitting and fixing the top plate I8 to one end of the secondary molded product 20.

Embodiment In the illustrated embodiment, FIG. 1 is a sectional view of a cap 9 formed by the above-described means.

This cap 9 has a double cylindrical shape in which the lower end of a short cylindrical outer wall 11 is inverted to provide a short circular cylindrical inner wall 13 whose height and width are slightly lower than the height and width of the outer wall 11. wall 1
A top wall 15 is integrally connected to the upper end of 3, and an inner wall 13
A thread 14 is provided around the periphery. .

A label 17 with predetermined printing is arranged on the "-" side of the top wall 15, and within the upper end of the outer wall 11 that projects slightly upwards from the top wall 15, the label 17
A top plate 18 made of transparent synthetic resin is fitted in the position of overlapping the top plate 7, and in this position, the upper end of the outer wall 11 is bent inward to form a curled part 16, and the peripheral end of the top plate 18 is bent inward. It is pressed down and fixed.

Next, FIG. 2 is a sectional view of a state in which a primary molded product 19 in the shape of a short cylinder with a bottom is molded.

First, with the upper surface of the movable mold 3 in the retracted position at almost the same height as the stepped portion 2, the heated synthetic resin sheet 10 is placed on the open end of the outer wall mold 1 via the holding plate 6. The mold 1 for the outer wall and the movable mold 3 are fixed by performing a pressure forming operation from the outer periphery of the jig 5 that moves downward and forward in the direction of the movable mold 3.
A primary molded product 19 in the shape of a short cylinder with a bottom is formed by the surface of the mold.

Then, while continuing the air pressure forming operation, the jig 5 is raised and retreated by 2", and the movable mold 3 is relatively raised and advanced to near the opening end of the outer wall mold 1, and the primary molded product 1 is moved back and forth.
9 is reversely stretched from the lower part of the outer wall 11 to the bottom wall 12 to form a short cylindrical shape with a top, which is composed of the inner wall 13 and the top wall 15 (see FIG. 3).

The part that is mainly stretched in this operation is the primary molded product 19.
However, some stretching will be added to the lower part of the outer wall 11. However, as described above, since the air pressure forming operation continues, the lower end of the outer wall 11 maintains a posture in which it is in contact with the mold surface of the stepped portion 2, and the circumferential surface of the movable mold 3 Since a part of the bottom wall 12 bites into the threaded groove 4, the threaded thread 14 is formed on the inner wall 13 to be molded.

FIG. 4 shows a state in which the movable mold 3 is lowered and retreated after being cooled to such an extent that the above-described configuration can be maintained, and the movable mold 3 is rotated to remove screws.

In FIG. 5, the upper end of the outer wall 11, which is the upper end of the primary molded product 19, is cut off from the remaining part of the synthetic resin seam 0 by moving the cutter 7 forward and downward, thereby creating a double-cylindrical secondary molded product 20.
It forms.

"Effect of the invention" As is clear from the above explanation, according to the camp molding method of the present invention, a synthetic resin sheet is sufficiently stretched to form a double cylinder shaped camp. The physical properties of the product are extremely excellent, and because of its double-cylindrical shape, it also has excellent mechanical strength, has a good appearance, is easy to wear, and is easy to mold. It has many excellent effects, such as:

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a camp formed according to the present invention. Fig. 2 is a cross-sectional view of the state in which the primary molded product is being molded. Fig. 3 is a cross-sectional view of the movable mold in the state of being moved forward and upward. FIG. 4 is a sectional view of the movable mold 3 in the unscrewed state. FIG. 5 is a sectional view showing the state in which the upper end of the primary molded product is cut off. Explanation of symbols 1; Mold for outer wall, 2; Step portion, 3; Movable mold, 4; Spiral groove, 9; Camp, 10; Synthetic resin sheet, 11; Outer wall, 13; Inner wall, 15; Top wall, 18; top plate, 19; primary molded product, 20. Secondary molded product.

Claims (1)

[Claims] an outer wall mold in which the inner diameter of the lower end of the cylindrical molding space is made slightly smaller and a stepped portion is formed on the inner peripheral surface; the outer wall mold has an outer diameter equal to the inner diameter of the lower end of the molding space of the outer wall mold; a movable mold having a cylindrical shape with a spiral groove carved on its circumferential surface and disposed in the outside wall mold so as to be able to move forward and backward; the flat upper surface of the movable mold is in contact with the stepped portion After forming a primary molded product in the shape of a short cylinder with a bottom by fixing a heated synthetic resin sheet to the open end of the outer wall mold at a retracted position at approximately the same height and performing pressure molding, While continuing the pressure forming operation, the movable mold is advanced to near the open end of the outer wall mold, the lower part of the primary molded product is inverted and stretched to form a short cylindrical body, and then the A cap characterized in that the upper end of the primary molded product is separated from the rest of the synthetic resin sheet to form a double cylinder-shaped secondary molded product, and a top plate is further fitted and fixed to the upper end of the secondary molded product. Molding method.