JPH0343977B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing a corrugated pipe having a spirally uneven outer surface and a smooth inner surface from a flat thermoplastic resin tape. An effective manufacturing method for corrugated pipes molded from thermoplastic resins such as polyethylene and polypropylene, which are difficult to cool and harden and have poor shape retention when molded, especially corrugated pipes with an uneven outer surface and a smooth inner surface. It is about providing.

Conventionally, the method for manufacturing this type of corrugated pipe with a smooth inner surface is to extrude a raw material tube from an extruder's dual inner and outer annular dies, apply internal pressure at a temperature above the softening point and below the melting point, and then insert the tube into a caterpillar-shaped rotating formwork. There are two known methods: pressing the wall surface of a cylinder to shape it, or spirally winding a band-shaped body with a convex part around a virtual cylindrical rotating shaft, polymerizing and bonding it, and forming it into a tube.The former method In this case, there is a problem that the device becomes extremely large and complicated, which increases manufacturing costs.On the other hand, in the latter method, a band-shaped body with a convex portion is wound helically around the circumferential surface of the rotating shaft. For this reason, if the cooling is insufficient, the bent convex part becomes flat due to the difference in the curvature rate between the flat part and the bent convex part, and conversely, in the case of hardening by forced cooling with cooling water, etc. However, as it hardens, it becomes difficult to wind it, and it also becomes difficult to fuse the strips together, making it impossible to form a tube.

The present invention has been researched and developed in view of the various drawbacks of the conventional manufacturing methods described above, and consists of a thermoplastic resin tape in a heated molten state discharged from a die of one extruder, and a spiral protrusion formed on the circumferential surface. The outer tube is wound in a helical direction around the circumferential surface of a rotary shaft body that is forcibly rotated to form an outer tube with an uneven cross section, while the heated and molten resin tape discharged from the other die is wound to make the circumferential surface smooth. An inner tube with a smooth circumferential surface is formed by winding it around the circumferential surface of the rotating shaft body, and the inner tube and the outer tube are overlapped inside and out and pressed and fused using the molten state of the material. In this way, we provide an extremely efficient manufacturing method that can continuously manufacture corrugated pipes whose outer circumferential surface has an uneven surface with spiral protrusions running through them, while the inner circumferential surface has a smooth surface. be.

Examples illustrating the present invention will be described below.
To explain its features in detail, Fig. 1 is a partially cross-sectional front view of the main parts of the manufacturing equipment, Fig. 2 is a left side view of the above figure, and Fig. 3 is an internal view of the manufacturing equipment. FIG. 4 is a partially cutaway front view illustrating the process of manufacturing a smooth corrugated pipe, and FIG. 4 is a partially cutaway right side view of the above figure.

In the drawings, reference numeral 1 is a first rotating shaft, 2 is a second rotating shaft provided continuously at the tip of the first rotating shaft, and 3 is a second rotating shaft provided opposite to the outer peripheral surface of the first rotating shaft 1. It is an outside die for discharging and molding the thermoplastic resin tape A, and 4 is an inside die for molding the thermoplastic resin tape B, which is installed near the axial center of the second rotating shaft.

The first rotating shaft body 1 includes a proximal bearing plate 5 vertically erected on a table (not shown), a base shaft 6 made of a metal pipe that extends horizontally through the proximal bearing plate 5, and a base shaft 6 made of a metal pipe that extends horizontally through the proximal bearing plate 5. 5, and a plurality of grooved rolls 8a, 8b, 8c, . . . 8i, which are passed between the two bearing plates.

The bearing plates 5 and 7 are respectively provided with bearing members 9 and 10 at equal intervals along an imaginary circumference drawn around the axis of the horizontally protruding base shaft 6, on which both ends of the grooved roll are supported. In particular, each of the rolls is rotatably supported, and the collection of these rolls constitutes one rotating shaft body having a substantially cylindrical shape.

Sprockets 11 and 12 are attached to the ends of each roll that penetrate through one bearing plate 5 and protrude to the other side.
sprocket 1 aligned on the same circumference on one side.
A chain 15 connected to an adjustment sprocket 14 rotated by a drive motor 13 is routed around the first group, and a chain 17 connected to a tension adjustment sprocket 16 is routed around the other 12 groups of sprockets aligned on the same circumference. 9 grooved rolls 8a, 8
b, . . . 8i are all forced to rotate in the same direction and at a constant speed.

In this embodiment, as shown in FIG. 2, a sprocket 11 is provided clockwise from the uppermost grooved roll 8a to roll 8f, and from rolls 8g to 8c.
A sprocket 12 is provided at each end of the rolls extending over the length of the rolls, so that the movement of one chain 15 causes all the grooved rolls to rotate at once in the same direction, substantially as if one rotating body were being rotated. There is.

Each of the above-mentioned grooved rolls is made by fitting ring members having a trapezoidal cross-section onto a round rod-shaped shaft rod, which are arranged and fixed at regular intervals to form a grooved roll having protrusions 18 at a constant pitch. It has been formed. Further, these grooved rolls can be manufactured by rotating one bearing plate 5 of the other bearing plate 7 by a required angle in one direction about the base shaft 6, and making the opposing bearing members 9 and 10 have different phases. The roll is twisted around the base shaft 6 to give it an inclination, thereby aligning the ring-shaped protrusions 18 formed on the roll in the helical direction between adjacent grooved rolls, and aligning the nine grooved rolls. Continuous spiral protrusions are formed on the circumferential surface of the first rotating shaft body configured by aggregation.

On the other hand, the second rotary shaft body 2 is connected to the first rotary shaft body 2 by passing a plurality of round rod-shaped rolls 20 between it and a front end bearing plate 19 provided opposite to the bearing plate 7.
Like the rotating shaft, it is formed into a single cylindrical rotating body.

As shown in the figure, the second rotating shaft body 2 is constituted by a combination of eight rolls, each of which runs along an imaginary circumference drawn around the extension of the axis of the base shaft 6. They are arranged at equal intervals, forming a cylindrical shape with a hollow shaft. These eight rolls are rotatably supported at both ends by bearing portions 21 provided opposite to each other on the bearing plate 7 and the front end bearing plate 19, and their substantial diameter is The body 2 is formed to have a diameter substantially equal to the diameter of the concave portion of the first rotating shaft body 1, but slightly smaller.

As described above, the first rotating shaft body 1 and the second
With respect to the rotating shaft body 2, an outside die 3 is provided opposite to the outer peripheral surface of the first rotating shaft body, and an inside die 4 is disposed opposite to the outer peripheral surface of the first rotating shaft body.
is installed in the hollow shaft center of the second rotating shaft body 2.
The latter inside die 4 faces the inside of the second rotary shaft body 2 via a die leg 22 that passes through the inside of the hollow base shaft 6, and the die leg is connected to an extruder (not shown), and heat is supplied from the two inner and outer dies. It is arranged so that melted thermoplastic resin tapes A and B can be discharged.

Next, a method for manufacturing a corrugated pipe with a smooth inner surface according to the present invention will be explained using the apparatus configured as described above.

In the manufacturing process, the resin tapes A and B heated and melted are simultaneously discharged from the two dies and supplied to each rotating shaft, but for convenience of explanation, the resin tape A discharged from the outside die 3 is
First, let me explain.

The resin tape A discharged from the outside die 3 with the required width and thickness is directed toward the outer circumferential surface of the proximal end of the first rotating shaft body 1 on the connection and in the direction of the spiral protrusion formed on the circumferential surface. Along the roll protrusion 18
It is supplied in such a way that it straddles the

The tape A supplied here is determined by the relationship between the pitch of the spiral protrusions and the tape width.
When the tape passes around the supply point and meets the next tape portion to be wound, it is fed so that some of the tape overlaps on the rotating shaft, and by continuing this, a spiral tube shape is formed.

The tube formed here is a spiral tube with a wave-shaped cross section of the tube wall because the tape A is bent by straddling the spiral protrusion, and this tube rotates as the tape is continuously supplied. The outer tube C is formed on the first rotating shaft body, which grows sequentially to form the second
It will advance onto the rotating shaft body 2 while rotating.

In the figure, reference numeral 23 denotes a pressure roll that is installed in parallel with one of the grooved rolls 8a of the rotating shaft body 1 at a required interval. are arranged at the same pitch, press the tape A wound around the rotating shaft body, and
8 to form an uneven shape, and the overlapping tapes A in a molten state are pressed together to form a tube body.

In contrast to the thus formed outer tube C, the heated and melted resin tape B discharged from the inside die 4 is formed into an inner tube D on the second rotating shaft.

In this embodiment, the tape B is discharged from the downward die as shown in FIG. 4, hangs vertically, and is automatically guided out of the rotating shaft through the gap between the rolls 20.

The tape B guided here comes into contact with the inner wall of the outer tube C that was first formed on the first rotating shaft body and advances while rotating on the second rotating shaft body 2, and is guided to the rotation of this outer tube. Then, it is wound onto the second rotating shaft so as to be drawn between the rolls 20 (see FIG. 4).

The tape B wound here is formed into a spiral tube shape by partially overlapping the tape A, forming an inner tube D, and this inner tube is connected to a second rotating shaft having a substantially smooth circumferential surface. This results in a smooth tubular body, which is molded so as to overlap inside the outer tube C having spiral protrusions.

Both tubes C and D are extended onto the second rotating shaft and are opposed to one roll 20.
3 and are fused together to form a corrugated tube with a smooth inner surface forming a double tube structure, and both of them are fed out through the second rotating shaft as the outer tube C is extruded. .

Figure 3 shows that two inner and outer tubes C and D are formed by winding the above-mentioned inner and outer tapes A and B around each rotating shaft, and that both tubes are press-joined on the second rotating shaft. FIG. 5 shows a partially enlarged sectional view of the completed corrugated pipe of the present invention.

Although it is unnecessary to explain, the resin tapes A,
Both tapes are in a heated and molten state, and when wound around the rotating shaft, the weight portions of the tapes are pressed and fused together at a temperature below the melting point and above the softening point to form a tube body, and together with the second rotating shaft. Tape B on the body
is also fused to the inner wall surface of the outer tube C and integrated.

As explained above, the present invention provides resin tape A, which is individually melted from each die 3 and 4, for the first and second rotating shaft bodies 1 and 2, which are arranged in front and behind with their axes aligned on a line. B is discharged, wound on each shaft body and formed into a spiral tube shape, and an outer tube C having a spiral protrusion and a smooth inner tube D are individually formed, while
By fusing these two tubes on the second rotating shaft body 2 and integrating them, a corrugated tube with a spiral protrusion on the outer surface and a smooth inner surface is manufactured. Continuous production is possible by supplying and winding the resin tape in accordance with the rotation of the corrugated pipe, and the manufactured corrugate pipe has a high flat strength due to the spiral protrusions on the outer surface, and has a smooth inner pipe. As a result, a corrugated pipe with a smooth inner surface can be obtained.

In the corrugated pipe according to the present invention, the outer tube molded on the first rotating shaft rotates and advances onto the second rotating shaft, and the tape B from the inside die is released.
Since the two pipes are integrated by rolling them together, the joint between the two pipes becomes stable, resulting in a high-quality corrugated pipe, which allows us to provide products with even higher reliability.

In the illustrated embodiment, forced cooling means are not particularly mentioned, but if each roll of the first and second rotating shafts is made hollow to form a cooling water circulation channel, a tubular cooling system can be formed on each rotating shaft. By cooling each resin tape wound around the tube, the tube shape can be hardened and stabilized at an early stage. Therefore, in practice, the combination of this forced cooling means to increase the manufacturing speed is exactly the same as in conventional manufacturing apparatuses of this type.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention.
The figure is a partially sectional front view of the main parts of the manufacturing equipment, Figure 2 is a left side view of the above figure, and Figure 3 is a partial explanation of the process of manufacturing a corrugated pipe with a smooth inner surface using the manufacturing equipment. FIG. 4 is a partially sectional front view of the cutout, FIG. 4 is a partially sectional right side view of the above figure, and FIG. 5 is a partially enlarged sectional view of a corrugated pipe manufactured by the method of the present invention. 1... First rotating shaft body, 2... Second rotating shaft body, 3
...Outside die, 4...Inside die,
5, 7... Bearing plate, 6... Base shaft, 8a to 8i...
Grooved roll, 18... Projection, 19... Front end bearing plate, 20... Roll, 23... Press roll, A,
B...Thermoplastic resin tape, C...Outer tube, D...
inner tube.

Claims (1)

[Claims] 1. A first rotating shaft that is forcibly rotated and has a virtual cylindrical shape with a spiral protrusion on its outer peripheral surface, and a second rotating shaft that rotates freely and has a virtual cylindrical shape with a smooth outer peripheral surface. First, a heated and molten thermoplastic resin tape discharged from an outside die of an extruder is applied to the circumferential surface of the first rotating shaft body so as to form the helical protrusion. While applying an inclination angle along this spiral protrusion so as to straddle the tape, the tape to be wound later is supplied so that it overlaps with the tape to be wound first, and is wound to create a spiral unevenness on the pipe wall. Extrusion forming an outer tube that is a flat surface, sequentially delivering the outer tube onto the second rotating shaft as the first rotating shaft rotates, and installing the outer tube near the axis of the second rotating shaft. Discharging a heated and melted thermoplastic resin tape from the inside die of the machine, guiding this tape between the outer peripheral surface of the second rotating shaft body and the inner wall surface of the outer tube that is sent out while rotating on the outer peripheral surface, A portion of the tape wound later is supplied so as to overlap the tape wound first to form a smooth inner tube on the second rotating body, and at the same time, the tape is fed parallel to the second rotating shaft. The inner wall surface of the concave portion of the outer tube and the outer wall surface of the inner tube are pressed and fused using pressure rolls arranged opposite to each other, and then cooled and hardened to smooth the inner surface and continuously form a tube body having spiral protrusions on the outer surface. A method for manufacturing a corrugated pipe with a smooth inner surface.