JPS5913971B2 - Method for manufacturing underdrain pipe with non-porous part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing synthetic resin underdrain pipes which are widely used for improving wet farmland, collecting land and drainage for reclaimed land, roads, golf courses, etc.

5. Japanese Patent Publication No. 43-15360 has been known as a method for manufacturing a synthetic resin underdrain pipe having a non-porous portion.

This involves reciprocating two sets of dies that have through holes on the inner and outer surfaces, and in areas where a mesh is to be formed and the holes should be made non-porous, the dies are shaved and resin is poured between the meshes to make them non-porous. be. This method requires more resin in one non-porous part than in the perforated part, so it is more expensive than a pipe with a mesh throughout (referred to as a fully perforated pipe). To rotate 2 dice,
The equipment is large-scale and expensive.

3. It has defects such as difficulty in adjusting resin flow.

The present invention eliminates these drawbacks and produces an underdrain pipe having a non-porous portion with the same amount of resin as a fully perforated pipe.

To explain the present invention, a groove of any shape on the out die! A rotating cutter is placed on the front surface of a pipe-shaped die with a plurality of 0 parts, and the extruded body made of synthetic resin is cut from the inside in a plastic state using the cutter, and the part that is not cut is stretched, and then cooled and solidified. Shape the mesh.

At this time, the cutter 5- is adjusted so as to make a cut of the same thickness over the entire circumference from the base to the L groove. Furthermore, the front surfaces of the out-die and in-die are made on the same surface, and the cut is made with a cutter that rotates in close contact with the same surface, thereby ensuring that the cut is made. For this reason, by rotating the cutter in close contact with the front surface of the die, the extruded resin is regulated by the die and has no room to escape, so that the cuts are complete and a neat mesh is formed. When forming a non-porous part, the cutter may be lifted above the front surface of the die 35 in the part to be made non-porous. By floating the cutter above the front of the die, the extruded resin has a greater degree of freedom, and the cut into the plastic tubular body is not complete.

2. The extruded resin tends to bulge in the outer circumferential direction immediately after extrusion due to the pressure inside the die, resulting in incomplete cuts.

etc. Therefore, a non-porous part is formed.

Note that the present invention can use a wide range of synthetic resins such as polyethylene, polypropylene, and polyvinyl chloride. The present invention will be explained in detail by examples. FIG. 1 shows a front view of the die opening of the embodiment.

A plurality of arbitrarily shaped grooves 2 are provided on the circumference of an out die 1 of an extrusion pipe shaping die, and a rotating cutter 4 is attached to the in die 3 side. The cutter 4 is adjusted so that the cut reaching the groove 2 from the base 5 has the same depth over the entire circumference. As shown in FIG. 2, in a portion a where a mesh is to be formed, the front surfaces of the out die 1 and the in die 3 are adjusted so that they are on the same plane, so that the cutters 4 are rotated in close contact with the same plane. The extruded body extruded from the die is cut and stretched in a plastic state with a cutter 14, and then cooled and solidified to form a mesh to form a perforated part. On the other hand, a non-porous part is formed by cutting the front surface of the out die 1 in the part b which should be made non-perforated and lifting the cutter 1 4' rearward from the part a which should be made perforated.

In that case, the cutting of the front surface of the out die may be about 1 to 20 mm. In addition, the cutter 14 indicated by a solid line in FIG. 1 and FIG.
′ indicates a lying position that is higher than the die. At this time, not only the out die 1 but also the surface of the in die 3 in the portion b which should be made non-porous may be cut in the same manner so that the cutter 1 is lifted above both the out die 1 and the in die 3. Note that the non-porous portion can be formed at any part of the circumference by processing the portion that should be non-porous as described above. FIG. 6 shows a perspective view of an underdrain pipe as an embodiment of the present invention.

In the above embodiment, the non-porous part was formed by pulling the out die of the part b which should be non-perforated to the rear of the part which should be perforated and letting the cutter 1 float above the die. As shown, the front surfaces of the out-die 1 and the in-die 3 are kept on the same surface over the entire circumference, and the cutters 4 are closely rotated in the portion a that should have holes to form a mesh, and the cams and By using a known method such as a solenoid, the cutter 4' may be lifted from the front surface of the die to form a non-porous portion.

In addition, in FIGS. 3 and 4, the cutter 14 is shown in a down position in close contact with the front surface of the die in the part that should be perforated, and the cutter 14' is shown in a state that it is lifted from the front surface of the die in the part that should be non-perforated. ing. As in the present invention, a method of making a cut with a rotating cutter to form a perforated part and at the same time forming a non-porous part is as shown in FIG. There is a method of forming a part, but the manufacturing of the die is expensive, and the thick part shrinks after molding, making it difficult to form a perfect circle.

The present invention has the advantages that it is easy to produce a perfect circle because the wall thickness is uniform over the entire circumference of one pipe, and that it is inexpensive because only several cutting operations are required on the front surface of two dies.

As described above, the present invention is significant in that it can eliminate known defects and manufacture high-performance underdrain pipes with inexpensive equipment.

[Brief explanation of drawings]

1 and 3 are front views of a die according to an embodiment of the present invention. FIGS. 2 and 4 are sectional views of essential parts of a die according to an embodiment of the present invention. FIG. 5 is a front view of a die of an embodiment according to a method similar to the present invention. FIG. 6 is a perspective view of an underdrain pipe according to an embodiment of the present invention.
1... Out die, a... Portion that should be perforated, 2... Groove portion, b... Portion that should be non-porous, 3... ...In-die, 4,4t...
・Katsuta 1 5...Base.

Claims (1)

[Scope of Claims] 1. A plurality of grooves of arbitrary shapes are provided on the circumference of an out die of a pipe-shaped die for extrusion, a rotating cutter is attached to the front surface of the die, and the rotating cutter reaches the grooves above the base. In this method, the rotary cutter is adjusted so as to make a deep cut, the cutter is used to cut into an extruded body made of synthetic resin in a plasticized state, and the part that is not cut is stretched to produce a mesh-structured tube. A non-porous part is formed by rotating the rotary cutter in close contact with the front surface of the die to form a perforated part, and at the same time forming a non-porous part by rotating the rotary cutter while floating the cutter from the front surface of the die. A method for manufacturing a synthetic resin underdrain pipe comprising: 2 In the part where the non-porous part is formed, the front surface of the out-die is pulled back from the part where the perforated part is formed, and the rotary cutter is rotated in a floating state in the same part to form the non-porous part.Claim 1 A method for manufacturing a synthetic resin underdrain pipe having a non-porous portion as described in 1. 3. A method for manufacturing a synthetic resin underdrain pipe having a non-porous portion as claimed in claim 1, wherein the rotary cutter is lifted from the front surface of the die by a cam in the portion where the non-porous portion is to be formed.