JP2000246771A - Method for molding resin molding having screw shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate removal of a resin molding having a screw shape in a short time. SOLUTION: The method for molding a resin molding having a screw shape in a mold for molding the molding having a bush provided with a protruding guide groove 8 including a twist angle similar to the screw shape of the molding and a protruding guide boss 7 connected perpendicularly to a protruding bar 6 comprises the step of rotating the bar 6 by rotating the boss along the groove to rotate the molding 4 connected to the bar 6 through a protrusion and recess shape or the like or an insert fitment 5, thereby drawing out the molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method suitable for obtaining a resin molded product having a screw shape such as a screw rotor for a compressor or a screw rotor for a supercharger. The present invention relates to a molding method for facilitating removal of a molded article.

[0002]

2. Description of the Related Art Conventionally, in order to obtain a screw- or screw-shaped molded product, a mold structure in which a cavity is divided has been used. . In this case, a parting line is formed on the surface of the molded product, and there is a disadvantage in that the surface is not smooth.

[0003] When such a dividing line is to be avoided, or when it is impossible to divide the molded product due to the screw shape, a method of protruding (or pulling out) the molded product in the axial direction has been adopted. In this case, the molded product comes out while rotating, but the mold release resistance due to the close contact between the mold surface and the resin molded product is large, and measures such as applying a rotating force or reducing the mold release resistance are taken. There are many cases where it cannot be taken out unless it is taken.

As a method for reducing the release resistance, a method is known in which a cooling mechanism is provided in a mold and the mold is cooled when a molded product is taken out (for example, Japanese Patent Application Laid-Open No. H10-1382).
However, the cooling and heating of the mold require a considerable amount of time, which has the disadvantage of increasing the production cost.

[0005]

The present invention has been made as a result of various studies in order to solve such problems caused by the conventional molding method. The purpose of the present invention is to improve the smoothness of the surface of a molded article. An object of the present invention is to obtain a resin molded product having a screw shape economically without any loss.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a mold for molding a resin molded article having a screw shape, the molded article or the insert fitting being connected to the ejected rod in an uneven shape by rotating the ejected rod. Is a method for molding a resin molded article having a screw shape, characterized in that the molded article is extracted by rotating.

FIG. 1 shows a screw rotor as an example of a resin molded product having a screw shape obtained by the present invention. This molded product includes an insert fitting (shaft) 21 and a resin screw portion 22.

A specific example of the method of the present invention will be described. FIG. 2 shows an example of a mold used in the present invention, FIG. 3 shows an example of a bush provided with a projecting guide groove, and FIG. 4 shows an example of a projecting rod provided with a projecting guide boss. 1 is the upper mold,
2 is a lower mold, 3 is a mold forming a cavity, 4 is a screw part (resin molding part), 5 is a shaft (insert fitting), 6 is a protruding rod, and 7 is integrally provided at right angles to the protruding rod. A projecting guide boss, 8 is a bush, 9 is a projecting guide groove provided in the bush, 10 is a bearing, and 11 is a projecting plate.

In such a mold, as a mechanism for taking out a molded product, a projecting plate 11, a projecting bar 6 in which a projecting guide boss 7 is integrally provided at a right angle, and a torsion angle similar to the screw shape of the molded product. Projection guide groove 9
And a bush 8 provided with the same. After the molding, the upper die 1 and the lower die 2 are opened, and when the molded product is extracted upward by raising the protruding plate 11 and the protruding rod 6, the protruding guide boss 7 and the protruding rod are protruded along the protruding guide groove 9 in the bush 8. 6 is rotated, and this rotation causes the protrusion rod 6 to have an uneven shape or the like.
The molded product or the insert metal fitting 5 connected to the upper end of the is rotated to extract the molded product.

In the present invention, the projecting guide groove 9 has a torsion angle similar to the screw shape of the molded product. If the twist angles are different, an excessive force is applied to the molded product side, which may cause abrasion on the molded product surface.

The projecting guide groove 9 and the projecting guide boss 7 are not particularly limited as long as the projecting guide boss can rotate along the projecting guide groove. The structure and shape shown in FIG.

The shape of the concavo-convex for use in the present invention for connecting the protruding rod to the molded product or the insert fitting is not limited as long as the molded product can be rotated simultaneously with the rotation of the protruding rod. However, a shape in which a local load is not applied to the molded product is desirable. For the same reason, when there is an insert fitting, it is preferable that the connection portion with the protruding rod is an insert fitting.

In order to facilitate the rotation of the protruding rod, a bearing 9 is provided at the connection between the protruding plate and the protruding rod.
It is desirable to install such.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the above-described method of the present invention is applied to the screw rotor shown in FIG. 1 will be described in comparison with a comparative example. Table 1 shows the time required for each step and the molding cycle in the case where the molding was performed using the mold shown in FIG. 2 and the molded product was taken out, together with the case where the molding was performed using the mold structure shown in FIG. In FIG. 5, reference numeral 12 denotes a cavity cooling pipe having a structure for cooling the cavity by passing cooling water therethrough. As is clear from Table 1, the method according to the embodiment can greatly shorten the molding cycle. The surface of the molded product obtained in the example was smooth without scratches and the like, and the ten-point average roughness (Rz) was 1.3 to 1.
6z, and a good value equivalent to that of the comparative example was obtained.

[0015]

[Table 1]

[0016]

According to the method of the present invention, a resin molded product having a screw shape can be obtained without impairing the smoothness of the surface of the molded product, and the molding cycle, which has been a disadvantage of the prior art, becomes longer. Since the problem of increased production cost is eliminated, it is suitable as a method for molding a resin molded product having an industrial screw shape.

[Brief description of the drawings]

FIG. 1 is an example of a screw rotor obtained by the present invention, wherein (a) is a front view and (b) is a plan view.

FIG. 2 is a side sectional view of an example of a mold used in the present invention.

FIG. 3 is an example of a bush provided with a protruding guide groove used in the present invention, where (a) is a side sectional view and (b) is a plan view.

FIG. 4 is a side sectional view of an example of a protruding rod to which a protruding guide boss used in the present invention is joined.

FIG. 5 is a side sectional view of a mold used in a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper mold 2 Lower mold 3 Mold which forms cavity 4 Screw part (resin molding part) 5 Shaft (insert fitting) 6 Projection rod 7 Projection guide boss 8 Bush 9 Projection guide groove 10 Bearing 11 Projection plate 12 Cavity cooling pipe 21 Insert bracket (shaft) 22 Resin screw part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B29L 31:08

Claims (2)

[Claims] In a mold for molding a resin molded product having a screw shape, by rotating a protruding rod, a molded product or an insert fitting engaged with the protruding rod in an uneven shape or the like is rotated to form a molded product. A method for molding a resin molded article having a screw shape, wherein the resin molded article is extracted. 2. A projecting guide groove having a projecting guide groove having a torsion angle similar to the screw shape of a molded article, and a projecting rod having a projecting guide boss formed at a right angle formed at a right angle. 2. The method according to claim 1, wherein the protruding rod is rotated by rotating the protruding guide boss along the axis.