JP3189183B2 - Corrugated pipe manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugate for extruding a thermoplastic thermoplastic resin into a cylindrical shape and forming spiral irregularities on the outer peripheral surface thereof by a split mold for forming an outer peripheral surface formed into a caterpillar chain. The present invention relates to an apparatus for manufacturing a pipe, and more particularly to an apparatus for manufacturing a corrugated pipe having a high durability of a molding block constituting the split mold for forming the outer peripheral surface.

[0002]

2. Description of the Related Art Conventionally, a corrugated pipe manufacturing apparatus of this type is formed into a caterpillar chain by connecting a number of molding blocks (molding blocks) as disclosed in Japanese Patent Publication No. 63-3785. There is known an apparatus provided with a split mold for forming an outer peripheral surface. The corrugated pipe manufacturing apparatus, the outer peripheral surface of a thermoplastic resin extruded into a tubular shape by an extruder provided adjacent to the outer peripheral surface forming split mold, is brought into contact with the molding block by blow molding. A spiral unevenness is formed on the outer peripheral surface.

[0003]

However, since the conventional molding block has spiral concave portions and convex portions formed on the corrugated tube molding surface, it is divided linearly at predetermined intervals as shown in FIG. Then, the thickness of the convex portion of the molding surface located at the edge of the divided surface (the contact end surface between the molding blocks) becomes thinner and sharper. The corrugated pipe cannot be manufactured with a predetermined accuracy due to chipping or bending of the part, and also the durability of the molding block itself is low and the life is short.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the various problems in the above-mentioned conventional manufacturing apparatus. An object of the present invention is to provide an apparatus for manufacturing a corrugated pipe in which the molding block itself can be manufactured with a high degree of durability and has a long life, by eliminating corrugated pipes with predetermined accuracy even by a change over time.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and is directed to a molding block having a spiral concave portion and a convex portion on a molding surface so that the concave portion and the convex portion are continuous. An apparatus for manufacturing a corrugated pipe having a substantially cylindrical molded portion in which two split molds for molding an outer peripheral surface connected in a chain shape are opposed to each other, wherein a tubular thermoplastic resin is provided inside the molded portion. In a corrugated pipe manufacturing apparatus for extruding spiral-shaped irregularities on the outer peripheral surface by extruding the outer peripheral surface of the thermoplastic resin into contact with the spiral concave and convex portions and performing blow molding,
The contact end faces where the blocks come into contact with each other have an inclined 2 formed along the spiral direction of the concave portion or the convex portion.
An apparatus for manufacturing a corrugated pipe, comprising: one surface and a step connecting the two inclined surfaces and intersecting a concave portion or a convex portion.

Here, the contact end surface of the molding block is formed to be inclined so as to follow the spiral direction of the spiral concave and convex portions on the molding surface, thereby continuously projecting spirally. The thickness of the protrusion near the contact end face is made constant. In addition, it is not necessary to incline the entire contact end surface, and at least the spiral concave portion, if the inclination is provided only to the contact end surface at the molding surface edge where the convex portion is provided, the thickness of the edge of the convex portion is reduced. It goes without saying that it is almost constant.

The step in the contact end face connects two inclined surfaces formed along the spiral direction of the concave portion or the convex portion, and intersects the concave portion or the convex portion.
The position at which the step is provided may be any position on the contact end face as long as the thickness of the helically projecting protrusion is constant, but the molding block may be moved. In view of the position of the center of gravity, a substantially central portion of the contact end face is preferable for the purpose of being brought into contact with and separated from each other. In addition, it is a matter of course that the step is a step which does not hinder the contact and separation of the contact surfaces of the molding block.

[0008]

According to the present invention, there are provided two inclined surfaces formed such that the contact end surface extends along the spiral direction of the concave portion or the convex portion;
Since the two inclined surfaces are connected to form a step that intersects with the concave portion or the convex portion, even when the molding blocks come into contact with or separate from each other during operation of the apparatus, the thin portion of the convex portion is eliminated. The end of the molding block does not chip or bend.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is an explanatory view schematically showing an embodiment of a corrugated pipe manufacturing apparatus according to the present invention, and is a view when viewed from behind a molding block toward a molding surface side. FIG. 2 is a perspective view showing one embodiment of a molding block used in the corrugated pipe manufacturing apparatus according to the present invention.

In the apparatus for manufacturing a corrugated pipe according to the present embodiment, a molding block 3 having a spiral concave portion 5 and a convex portion 6 on a molding surface 4 is connected so that the concave portion 5 and the convex portion 6 are continuous with each other. A substantially cylindrical molded part 1 in which two split molds 2 for molding the outer peripheral surface formed in a chain shape are opposed to each other.
A thermoplastic resin extruding section (not shown) for extruding a tubular thermoplastic resin P into the inside of the molding section 1; and a cooling section (not shown) disposed in front of the thermoplastic resin extruding section. Is constituted.

Here, the molding block 3
As shown in FIG. 2, a spiral concave portion 5 and a convex portion 6 are provided on a molding surface 4. Further, the contact end faces 7 where the molding blocks 3 come into contact with each other are formed in the concave portions 5.
Alternatively, two inclined surfaces formed along the spiral direction of the convex portion 6 and the two inclined surfaces are connected to form the concave portion 5 or the convex portion 6.
And a step 8 intersecting with.

Although this embodiment does not disclose that the molding block 3 is formed in the shape of a caterpillar chain or its driving device, it is similar to the conventional corrugated pipe manufacturing device. The description is omitted because it depends on the configuration.

The apparatus for manufacturing a corrugated pipe according to the above embodiment operates as follows. First, a thermoplastic resin P is extruded into a tubular shape from a thermoplastic resin extruding part (not shown) inside the molding part 1. Outer peripheral surface P1 of the thermoplastic resin P
Is brought into contact with the molding surface 4 of the outer peripheral surface molding split mold 2 which proceeds at the same speed as the extrusion speed of the thermoplastic resin P, and the molding surface 4
Is blow-molded into the shape of the spiral concave portions 5 and convex portions 6. The molded thermoplastic resin P is cooled by a cooling unit (not shown) to achieve stabilization.

In the operation described above, the split mold 2 for molding the outer peripheral surface is such that the molding blocks 3 are in contact with each other at the position of the molding portion 1 and are connected linearly. At the point where the caterpillar turns back, the molding blocks 3 are moved at predetermined intervals, and the abutment / separation of the molding blocks 3 occurs.

In this embodiment, the contact end surfaces 7 where the molding blocks 3 come into contact with each other are two inclined surfaces formed along the spiral direction of the concave portion 5 or the convex portion 6; Since the two inclined surfaces are connected to form a step 8 which intersects the concave portion 5 or the convex portion 6 and the spiral convex portion 6 of the molding surface 4 is formed to have a constant thickness, the molding block during operation of the apparatus. Even if the three members come into contact with or separate from each other, the edge of the convex portion is not chipped or bent. In addition, a step 8 is provided substantially at the center of the contact end face 7 of the molding block 3, and the center of gravity is located substantially at the center similarly to the conventional molding block 3,
Accordingly, even if the molding blocks 3 come into contact with or separate from each other, the molding blocks 3 can be moved stably, and the device itself can be operated stably.

[0016]

According to the present invention, a spiral concave portion and a convex portion are provided on a molding surface of a molding block of a corrugated pipe manufacturing apparatus, and the contact end surface where the molding blocks come into contact with each other is formed by the concave or convex portion. Two inclined surfaces formed along the spiral direction of the portion,
It is formed of a step that connects two inclined surfaces and intersects with the concave or convex portion, so that the edge of the convex portion is not chipped or bent even if there is an action of abutment / separation between the molding blocks during operation of the device. This has the effect that the molding block is resistant to changes over time, the service life can be prolonged, and the quality of the corrugated pipe manufacturing apparatus itself can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing an embodiment of a corrugated pipe manufacturing apparatus according to the present invention, and is an explanatory view when viewed from behind a molding block toward a molding surface side.

FIG. 2 is a perspective view showing one embodiment of a molding block used in the corrugated pipe manufacturing apparatus according to the present invention.

FIG. 3 is an explanatory view schematically showing a conventional apparatus for manufacturing a corrugated pipe, and is an explanatory view when viewed from behind a molding block toward a molding surface side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molding part 2 Split mold for outer peripheral surface molding 3 Molding block 4 Molding surface 5 Concave part 6 Convex part 7 Contact end surface 8 Step P Thermoplastic resin P1 Outer peripheral surface

Claims (1)

(57) [Claims] 1. A molding block 3 having spiral concave portions 5 and convex portions 6 on a molding surface 4.
A corrugated pipe manufacturing apparatus having a substantially cylindrical molding portion 1 in which two outer peripheral surface molding split dies 2 which are continuously connected in a caterpillar chain shape so as to be continuous are opposed to each other. 1, the tubular thermoplastic resin P is extruded, and the outer peripheral surface P1 of the thermoplastic resin P is brought into contact with the helical concave portions 5 and the convex portions 6 and blow-molded.
In the apparatus for manufacturing a corrugated pipe for forming a spiral unevenness in the first embodiment, the contact end face 7 where the molding blocks 3 are in contact with each other is a spiral of the concave part 5 or the convex part 6.
Two inclined surfaces formed along the direction;
Step 8 that connects two inclined surfaces and intersects concave portion 5 or convex portion 6
An apparatus for manufacturing a corrugated pipe, comprising: