JPH06367B2 - Cap molding method - Google Patents

Description

The present invention relates to a method for molding a double-tube-shaped synthetic resin cap.

"Prior Art" Generally, a cap that is screwed into a mouth tube of a container is injection-molded with a synthetic resin, but since mechanical strength must be increased, the cap is inevitably thickened, and therefore, the resin is used. A large amount of the material is consumed, the weight is heavy, and a so-called sink phenomenon occurs particularly in a thick portion to form a slight unevenness on the surface, so that there is a drawback that the appearance is deteriorated.

In order to eliminate this drawback, for example, a means for thinning the thick portion can be considered, but the molding die becomes complicated and there is a disadvantage that the molding is troublesome.

[Problems to be Solved by the Invention] The present invention is a cap molding method developed to eliminate the above-mentioned conventional drawbacks and inconveniences. A cap having high mechanical strength, light weight, and good appearance is easily formed. The purpose is to enable molding.

"Means for Solving Problems" and "Operation" In the cap molding method of the present invention, an outer wall metal having a stepped portion 2 formed on the inner peripheral surface is formed by slightly reducing the inner diameter at the lower end of a cylindrical molding space. A mold 1 and a columnar shape having an outer diameter equal to the inner diameter of the lower end of the molding space of the outer wall mold 1 and having a spiral groove 4 formed on the peripheral surface thereof. This is carried out by the movable mold 3 that is movably arranged.

First, the movable mold 3 stands by at a retracted position where the flat upper surface thereof is substantially at the same height as the step 2, and the heated synthetic resin sheet 10 is attached to the open end of the outer wall mold 1. Fixed molded product with a bottom and a short cylinder shape
Forming 19.

After that, the movable mold 3 is continued while the pressure forming operation is continued.
To the vicinity of the open end of the outer wall mold 1 to invert and extend the lower part of the primary molded product 19 to form a capped short tubular body, and then the upper end of the primary molded product 19 is subjected to the synthesis. Double-molded secondary molded product separated from the rest of the resin sheet 10
Forming 20.

Further, the top plate 18 is fitted and fixed to the upper end of the secondary molded product 20 to mold the cap 9.

[Example] In the illustrated example, FIG. 1 is a cross-sectional view of the cap 9 molded by the above-described means.

The cap 9 has a double-cylindrical shape in which the lower end of the outer wall 11 having a short cylindrical shape is inverted and the inner wall 13 having a short cylindrical shape slightly lower than the height width of the outer wall 11 is provided. A top wall 15 is integrally connected to the upper end of the, and a thread 14 is provided around the inner wall 13.

Then, a label 17 having a predetermined print is arranged on the upper surface of the top wall 15, and in the upper end portion of the outer wall 11 projecting slightly higher than the top wall 15, a posture of stacking on the label 17 is provided. Then, the transparent synthetic resin top plate 18 is fitted, and in this posture, the upper end of the outer wall 11 is bent inward and the curl portion is bent.
16 is formed, and the peripheral edge of the top plate 18 is pressed and fixed.

Next, FIG. 2 is a cross-sectional view of a state in which a primary molded product 19 having a short tubular shape with a bottom is molded.

First, with the upper surface of the movable mold 3 in a retracted position in which the upper surface of the movable mold 3 is substantially at the same height as the stepped portion 2, the heated synthetic resin sheet 10 is inserted into the open end of the outer wall mold 1 via the pressing plate 6. A compressed air molding operation is performed from the outer periphery of the jig 5 that is fixed and moves down and forward in the direction of the movable mold 3, and the outer wall 11 and the bottom wall 12 are formed by the molding surfaces of the outer wall mold 1 and the movable mold 3. A primary molded product 19 having a bottomed short tubular shape is formed.

Then, the jig 5 is moved upward and backward while continuing the pressure forming operation, and the movable mold 3 is relatively moved to the outer wall mold 1.
Of the primary molded product 19 is inverted and extended from the lower part of the outer wall 11 to the bottom wall 12 of the primary molded product 19 to form a capped short tubular shape composed of an inner wall 13 and a top wall 15. (See FIG. 3).

The portion that is mainly stretched by this operation is the bottom wall 12 of the primary molded product 19, but some stretching will also be applied to the lower portion of the outer wall 11. However, as described above, since the compressed air molding operation is continued, the lower end of the outer wall 11 maintains the posture in which it is in contact with the molding surface of the stepped portion 2 and the peripheral surface of the movable mold 3 is kept. Since a part of the bottom wall 12 bites into the thread groove 4, the 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 retracted after being cooled to such an extent that the above-described form can be retained, and the movable mold 3 is rotated to perform screw removal.

Then, in FIG. 5, the cutter 7 is moved down and forward to separate the upper end of the outer wall 11 which is the upper end of the primary molded product 19 from the rest of the synthetic resin sheet 10 to form the double cylindrical secondary molded product 20. Of.

[Advantage of Invention] As is clear from the above description, according to the cap molding method of the present invention, the synthetic resin sheet is sufficiently stretched to mold the double cylindrical cap. It has excellent physical properties as a product, and also has excellent mechanical strength due to its double-cylindrical shape, good appearance, easy label attachment, easy molding, etc. Has the excellent effect of.

[Brief description of drawings]

FIG. 1 is a sectional view of a cap molded according to the present invention. FIG. 2 is a cross-sectional view of a state where a primary molded product is molded. FIG. 3 is a cross-sectional view of a state where the movable mold is raised and advanced. FIG. 4 is a cross-sectional view of the movable die 3 in the unscrewed state. FIG. 5 is a sectional view showing a state where the upper end of the primary molded product is cut off. Explanation of reference numerals 1: Mold for outer wall, 2; Step part, 3; Movable mold, 4; Screw groove, 9; Cap, 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] 1. A mold for an outer wall having a stepped portion formed on the inner peripheral surface thereof with the inner diameter of the lower end of a cylindrical molding space being made slightly smaller, and an outer diameter equal to the lower end inner diameter of the molding space of the outer wall mold. Has a diameter
A movable mold having a cylindrical shape with a spiral groove engraved on its peripheral surface and arranged so as to be able to move forward and backward within the mold for the outer wall, and the flat upper surface of the movable mold is the stepped portion. After the heated synthetic resin sheet is fixed to the open end of the outer wall mold and pressure-molded at a retracted position of substantially the same height, after forming a bottomed short cylinder-shaped primary molded product, While continuing the compressed air molding operation, the movable mold is advanced to the vicinity of the open end of the mold for the outer wall, and the lower part of the primary molded product is inverted and stretched to form a capped short tubular body, and then the A cap characterized by cutting the upper end of the primary molded product from the remainder of the synthetic resin sheet to form a double-cylindrical secondary molded product, and further fitting and fixing a top plate on the upper end of the secondary molded product. Molding method.