JP2602886Y2 - Annular base - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion die for producing a tube made of a thermoplastic resin, and more particularly to an annular die capable of producing a stable and long-term production with a small amount of resin stagnation.

[0002]

2. Description of the Related Art There are various types of annular bases, and a base as shown in the schematic partial cross-sectional view of FIG. 3 is called a spiral base. Resin stays in the gap t for preventing seizure between the die ring 10 and the inner mold 11 and easily deteriorates due to heat. Therefore, depending on the type of the thermoplastic resin, the heat-degraded resin becomes foreign matters such as burns or lowers the viscosity. This causes a problem that the appearance of the tube is impaired and that stable long-term production is impossible.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has found a ring-shaped die which is stable in resin and can be produced for a long period of time. The gist of the invention is as follows. An outer die 1 having a concave cross-section and an inner die 3 disposed inside the inner die 3, and a spiral groove 9 formed in the side surface of the inner die 3. A plurality of resin distribution paths 7 communicating from the resin supply port 5 to the spiral grooves 9 are radially provided on the mating surface, and the resin distribution paths 7 are curved before communicating with the spiral grooves 9. An annular die is characterized in that a resin flow path 8 is provided in a part of the outer mold 1 in a communicating part.

Hereinafter, the present invention will be described with reference to the drawings. FIG.
FIG. 2 is a schematic sectional view showing an example of the die according to the present invention, and FIG. 2 is a partially cutaway plan view of the die shown in FIG. As shown in FIG. 1, the die according to the present invention has a structure in which an outer die 1 having a concave cross-section and an inner die 3 are disposed inside the die as in a conventional die. Die ring 1
2 are combined and fastened together with fastening bolts.
A spiral groove 9 is engraved on the side surface of the inner die 3, and an adjustment lip 4 is provided near the resin discharge port.

[0005] The supplied resin is radially distributed from the resin supply port 5 by a plurality of resin distribution paths 7, and then the resin flow flowing along the spiral groove 9 and the axial flow flowing over the spiral groove 9 are synthesized. The resin flow becomes more uniform, the thickness is adjusted by the adjusting lip 4, and the resin is discharged from the lip.

The base according to the present invention can prevent the stagnation of the resin by forming the resin distribution path 7 into a specific shape. As shown in FIG. In addition, a plurality of resin distribution paths 7 are provided radially from the resin supply port 5 at the center of the die, and the resin distribution paths 7 are curved before communicating with the spiral grooves 9 to provide a curved portion 71. A resin flow path 8 is provided in a part of the outer mold 1 in the communicating part.

As described above, the curved portion 71 is provided in the resin distribution path 7 and the resin flow path 8 is provided in a part of the outer mold 1. Since the direction changes once in the path 8 and flows into the spiral groove 9, there is no stagnation of the resin. Here, the degree of bending in the bending portion 71 and the size of the resin flow path 8 provided in a part of the outer mold 1 can be appropriately determined depending on the type of resin to be used, the temperature of the die, etc. be able to.

[0008]

As described above, according to the annular die of the present invention, since there is little stagnant portion of the resin, it is possible to produce a stable thermoplastic resin tube for a long time even with a resin having poor thermal stability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of the present invention;

FIG. 2 is a partially cutaway plan view taken along AA of the base shown in FIG. 1;

FIG. 3 is a schematic partial cross-sectional view of a conventional base.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 outer die 12 die ring 3 inner die 5 resin supply port 7 resin distribution path 8 resin flow path 9 spiral groove

Claims (1)

(57) [Scope of request for utility model registration] 1. An annular die having an outer mold (1) having a concave cross section and an inner mold (3) disposed therein, and a spiral groove (9) formed in a side surface of the inner mold (3). A plurality of resin distribution paths (7) radially provided from the resin supply port (5) to the spiral groove (9) on the bottom surface of the inner mold (3) and the mating surface with the outer mold (1); A resin flow path (8) is provided in a part of the outer mold (1) which is curved before communicating with the spiral groove (9) of the resin distribution path (7) and communicates with the spiral groove (9). An annular base, characterized in that: