JP2003285360A - Method and device for manufacturing flexible composite pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a flexible composite pipe by which a flexible composite pipe having stable bending characteristics with the reduced pitch variation and dispersion of an interlocking pipe can be efficiently manufactured, and a device for manufacturing the pipe. <P>SOLUTION: The method for manufacturing a flexible composite pipe is as follows: before forming a plastics pipe on the interlocking pipe 1, the pitch between engagement parts 1A of the interlocking pipe 1 is elongated to more than a neutral pitch size where the stretch amount and the shrink amount of the engagement parts 1A are equalized to each other by stretching the engagement parts 1A in the axial direction of the pipe; then, the pitch between the engagement parts 1A is adjusted by reducing the pitch so that it is equal to the neutral pitch size; and in such a state that the pitch between the engagement parts 1A is kept at the neutral pitch size, a plastics material is extruded onto the interlocking pipe 1 directly or through an interposed layer to coat the interlocking pipe 1, thus forming the plastics pipe. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a flexible composite pipe used for fluid transport pipes, electric wire pipes, cable armor pipes and the like.

[0002]

2. Description of the Related Art Conventionally, for example, as a fluid transport pipe, a pipeline in which a short rigid metal pipe is connected in the longitudinal direction or a flexible composite pipe mainly composed of a plastic pipe is used. The latter flexible composite pipe prevents buckling of the plastic pipe 3 due to bending, as shown in FIG.
In order to protect the inner surface of the plastic pipe 3 from external damage when regularly cleaning dirty oil such as crude oil and mud adhered to the inside of the plastic pipe 3 with a wire, a brush, etc., The interlock pipe 1 is installed in the
Plastic tube 3 on top of plastic tube 3 as required
It is configured by providing a metal reinforcing layer 4 and a plastic outer sheath 7 for reinforcing the internal pressure and the axial force.

More specifically, as shown in detail in FIG. 4, the interlock tube 1 is formed by bending both side edges of a metal tape 2 made of steel into an S shape or a Z shape (not shown) for engagement. 2A and 2B are formed, the metal tape 2 is spirally wound at a predetermined pitch, and adjacent engaging hooks 2A and 2B are engaged with each other to form a spiral engaging portion 1A. The plastic pipe 3 is provided by extruding and covering the interlock pipe 1 with a plastic material such as nylon or high-density polyethylene.

The metal reinforcing layer 4 has a concave portion at the center and two steel strips having a substantially C-shaped cross section having convex portions on both side edges, which are laminated in opposite layers and wound at a short pitch while engaging the concave and convex portions with each other. And the inner pressure reinforcing layer 5 and a plurality of flat steel strips wound on the inner pressure reinforcing layer 5 at a long pitch in the inner and outer layers so that the winding directions of the inner layer and the outer layer are opposite to each other. And an axial force reinforcing layer 6 formed as described above. In addition, 8 is, if necessary, between the interlock pipe 1 and the plastic pipe 3, between the internal pressure reinforcing layer 5 of the metal reinforcing layer 4 and the axial force reinforcing layer 6, between the flat steel strips of the axial force reinforcing layer 6, An intervening layer such as a tape winding layer or a resin extrusion buffer layer formed by winding a tape of paper, cloth, plastic or the like spirally or vertically between the axial force reinforcing layer 6 and the outer sheath 7. is there.

[0005]

The interlock pipe 1 which constitutes such a flexible composite pipe is expandable and contractible due to its structural characteristics, while it is expandable and contractible. There is a drawback that it tends to expand or contract due to the action of. Therefore, in order to manufacture the flexible composite pipe, when the plastic pipe 3 is provided by extrusion coating the plastic material on the interlock pipe 1 directly or through the intervening layer, the interlock pipe is formed until the extrusion coating step at the latest. Unreasonable tension or compressive force acts on the interlock pipe 1 while the vehicle 1 is traveling, so that the pitch P (see FIG. 4) between the engaging portions 1A of the interlock pipe 1 fluctuates and varies. It will be easier. In such a state, the interlock pipe 1
When the plastic pipe 3 is provided by directly extruding and covering a plastic material on the above or through the intervening layer, the flexible composite pipe in which the pitch P between the engaging portions 1A of the interlock pipe 1 varies is produced. Increased risk of being manufactured.

Generally, the engaging portion 1A of the interlock tube 1
The pitch P between them is preferably equal to the neutral pitch length at which the extension amount and the contraction amount of the engaging portion 1A in the pipe axis direction are equal. However, if the pitch P between the engaging portions 1A of the interlock pipe 1 varies, the pitch P between the engaging portions 1A becomes longer or shorter than the neutral pitch length along the longitudinal direction of the interlock pipe 1. There is a place to
The engaging portion 1A at the portion where the pitch P varies expands, but does not substantially contract, or contracts but hardly expands, which causes a problem that the bending characteristics of the flexible composite tube become unstable.

For example, when the pitch P between the engaging portions 1A of the interlock pipe 1 in the flexible composite pipe is too long and is longer than the neutral pitch length, the flexible portion is flexible. When a composite pipe is bent, the elongation cannot be absorbed outside the bend where tensile strain acts on the composite pipe. Even before the plastic pipe 3 is provided, the inside of the bend can be easily contracted even in such a state, so that the interlock pipe 1 can be bent, but the plastic pipe 2 reinforces the outside of the interlock pipe 1. If this happens, the shrinkage inside the bend will be greatly constrained,
The engaging hook 2A of the engaging portion 1A of the interlock tube 1,
Problems such as deformation of 2B occur.

On the contrary, when the pitch P between the other engaging portions 1A is too smaller than the neutral pitch length and is in a fully compressed state, a similar problem occurs. That is, when the flexible composite pipe is bent at this portion, the shrinkage cannot be absorbed inside the bend where compressive strain acts due to the bending. Even before the plastic pipe 3 is provided, the outside of the bend easily extends even in such a state, so that the interlock pipe 1 can be bent. However, the plastic pipe 2 reinforces the outside of the interlock pipe 1. If this happens, the extension outside the bend will be greatly restricted. Such a problem occurs not only in the flexible composite pipe for the fluid transport pipe, but also in the flexible composite pipe used for the electric wire pipe or the cable armored pipe.

The present invention has been made to solve the above-mentioned problems, and the pitch between the engaging portions of the interlock pipe becomes equal to the neutral pitch length, the pitch fluctuation and variation are reduced, and stable bending characteristics are achieved. An object of the present invention is to provide a method and an apparatus for manufacturing a flexible composite pipe capable of efficiently manufacturing a flexible composite pipe having the above.

[0010]

According to the invention described in claim 1 of the present invention, both side edges of the metal tape are bent into an S-shape or a Z-shape to form an engaging hook, and the metal tape is formed into a predetermined shape. A plastic material is extruded and coated directly or through an intervening layer on an interlock tube formed by spirally winding at a pitch and engaging adjacent engaging hooks with each other to form a spiral engaging portion. In the method of manufacturing a flexible composite pipe in which a plastic pipe is provided, the engaging portion of the interlock pipe is stretched in the pipe axial direction to form a pitch between the engaging portions before the plastic pipe is provided on the interlock pipe at the latest. Once longer than the neutral pitch length at which the extension amount and the contraction amount of the engaging portion are equal, then the pitch of the engaging portion is shortened and adjusted to be equal to the neutral pitch length. While maintaining the pitch in a neutral pitch in length, it has become coated extruded plastics material providing a plastic tube structure directly or through an intervening layer over the interlock pipe.

With such a structure, when the plastic material is extruded and coated on the interlock tube to provide the plastic tube at the latest, an unreasonable tension or compression force acts on the interlock tube to cause the interlock tube to engage. Since the pitch between the joints does not fluctuate and fluctuate and the pitch between the engaging portions of the interlock pipe is maintained at a substantially neutral pitch length, a flexible composite pipe with stable bending characteristics is manufactured. can do.

According to a second aspect of the present invention, the engaging portion of the interlock pipe according to the first aspect is stretched in the axial direction of the pipe so that the pitch of the engaging portion is extended and contracted. The pitch of the engaging part that is once longer than the neutral pitch length that makes them equal, and the engaging part pitch that adjusts the pitch of the engaging part that is longer than the neutral pitch length to be equal to the neutral pitch length. An adjusting machine, and a plastic pipe extruder in which a plastic pipe is provided by extruding and covering a plastic material directly or through an intervening layer on an interlock pipe in which the pitch of the engaging portion is adjusted to a neutral pitch length, and The engaging part pitch adjuster includes a plurality of worms in which spiral teeth having a pitch equal to the neutral pitch length of the engaging part of the interlock pipe are projected on the outer periphery of the worm shaft, and the worms. The worm has a drive source that is driven to rotate in accordance with the feeding speed of the interlock pipe, and rotates a plurality of worms around the outer circumference of the interlock pipe so that the teeth bite into the gaps between the engaging parts of the interlock pipe. It is configured by being freely arranged.

With such a structure, the pitch between the engaging portions of the interlock pipe before the plastic pipe is provided is adjusted to be equal to the neutral pitch length by using the engaging portion pitch adjuster having a worm. Because
A flexible composite pipe having stable bending characteristics over the entire length can be efficiently manufactured at low cost.

According to a third aspect of the present invention, the engaging portion of the interlock pipe according to the first aspect is stretched in the axial direction of the pipe so that the pitch of the engaging portion is extended and contracted. The pitch of the engaging part that is once longer than the neutral pitch length that makes them equal, and the engaging part pitch that adjusts the pitch of the engaging part that is longer than the neutral pitch length to be equal to the neutral pitch length. An adjusting machine, and a plastic pipe extruder in which a plastic pipe is provided by extruding and covering a plastic material directly or through an intervening layer on an interlock pipe in which the pitch of the engaging portion is adjusted to a neutral pitch length, and The engaging part pitch adjuster is arranged on the outer circumference of the worm shaft such that the upstream side in the traveling direction of the interlock pipe is longer than the neutral pitch length between the engaging parts and the downstream side is equal to the neutral pitch length from the upstream side to the downstream side. On the side And a plurality of worms having spiral teeth having a pitch that gradually decreases, and a drive source for rotationally driving the worms in accordance with the feeding speed of the interlock pipe. The worm is rotatably arranged on the outer circumference of the interlock tube so that its teeth bite into the gaps between the engaging portions of the interlock tube.

According to this structure, the teeth of the worm of the engaging portion pitch adjuster surely bite into the gap between the engaging portions of the interlock pipe, so that the pitch between the engaging portions of the interlock pipe can be made smoother. Since it can be adjusted to be equal to the neutral pitch length, a flexible composite pipe having more stable bending characteristics can be manufactured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of an apparatus for manufacturing a flexible composite pipe according to the present invention, and FIG. 2 is an explanatory view showing an enlarged state of use of an engagement portion pitch adjuster, which is a main portion thereof. is there. In addition, the same reference numerals are used for those having the same configurations and functions as those described in the related art, and the description thereof is omitted or simplified in order to avoid duplication.

The manufacturing apparatus of the flexible composite pipe of this embodiment is
As shown in FIG. 1, a feeding device 9 for feeding the interlock pipe 1, a pitch expansion device 10 for the engaging portion of the interlock pipe 1,
Engaging part pitch adjuster 11, plastic pipe extruder 12,
The flexible composite pipe A is provided with a take-up machine 13, and is arranged in tandem (longitudinal arrangement) along the traveling direction of the interlock pipe.

The engaging portion pitch expanding machine 10 is constructed by arranging, for example, two endless track type take-up machines 10A and 10B in tandem along the traveling direction of the interlock pipe 1, and is fed from the feeding machine 9. The interlock pipe 1 is taken out and supplied to the engaging portion pitch adjuster 11 arranged rearward. When the interlock pipe 1 is pulled, the control means is set so that the take-up speed of the endless track type take-up machine 10B arranged at the rear stage is always higher than the take-up speed of the endless track type take-up machine 10A arranged at the front stage. (Not shown). As a result, the engaging portion 1A of the interlock pipe 1 pulled by the engaging portion pitch enlargement machine 10 is stretched in the pipe axial direction, and the pitch between the engaging portions becomes longer than before entering the enlargement machine 10. The pitch becomes longer as the take-up speed difference between the endless track take-up machines 10A and 10B becomes larger.
Therefore, by setting the take-up speed difference to a desired value, the pitch between the engaging portions 1A of the interlock tube 1 becomes longer than the neutral pitch length at which the extending amount and the contracting amount of the engaging portion 1A are equal. Is controlled.

The interlock pipe 1 is stretched to the maximum allowable length, and the pitch between the engaging portions 1A is set to the engaging portion 1A.
If the extension amount is increased to the maximum, the pitch of the engaging portion 1A is shortened by the engaging portion pitch adjuster 11 and the pitch is adjusted to be more surely equal to the neutral pitch length. It is possible because it is possible.

The engagement portion pitch adjuster 11 is disposed behind the engagement portion pitch enlarger 10 and shortens the pitch of the engagement portion 1A which is longer than the neutral pitch length to be equal to the neutral pitch length. Have the function of adjusting so. As shown in FIG. 2, the engagement portion pitch adjuster 11 includes two worms 14 and 15 having spiral teeth 17 protruding from the outer circumference of a worm shaft 16 and two worms 14 and 15. It has a drive source 18 such as a motor that is connected through a transmission unit 19 such as a gear, a chain, or a belt, and that is driven to rotate in accordance with the feeding speed of the interlock tube 1.

The teeth 17 of the worms 14 and 15 are provided on the outer circumference of the worm shaft 16 in a spiral shape in the direction opposite to the engaging portion 1A of the interlock tube 1 so as to project in a triangular shape at their tips. ing. The worms 14 and 15 are rotatably arranged so as to face the outer circumference of the interlock pipe 1 by 180 degrees, and the tapered tips of the spiral teeth 17 bite into the gap between the engaging portions 1A of the interlock pipe 1. It is like this. Then, the worms 14, 15 are rotationally driven by the drive source 18 in accordance with the payout speed of the interlock tube 1 which is paid out in the direction of the arrow in FIG.

In the spiral teeth 17 of the worms 14 and 15, the pitch P1 at the upstream side (the right side in FIG. 2) in the traveling direction of the interlock tube 1 is such that
Is longer than the neutral pitch length between the engaging portions, the pitch P2 of the portion on the downstream side (left side in FIG. 2) in the traveling direction is equal to the neutral pitch length, and the pitch of the intermediate portion is from the upstream side to the downstream side. It is projected so that it becomes gradually shorter toward.

As described above, the pitch of the spiral teeth 17 of the worms 14 and 15 is longer than the neutral pitch length between the engaging portions on the upstream side in the traveling direction of the interlock pipe, and is set to the neutral pitch length on the downstream side. If it is configured to gradually become shorter from the upstream side to the downstream side so as to be equal,
The spiral teeth 17 of the worms 14 and 15 surely bite into the gap between the engaging portions 1A of the interlock tube 1, and are guided by the spiral teeth 17 which are gradually shortened to engage the interlock tube 1. It is preferable because the pitch between the portions 1A can be adjusted more smoothly to be equal to the neutral pitch length, and a flexible composite pipe having more stable bending characteristics can be manufactured.

Although not shown, the pitch of the spiral teeth 17 of the worms 14, 15 is equal to the neutral pitch length of the interlock pipe 1 from the upstream side to the downstream side in the traveling direction. You may comprise so that it may become. Even when the worm having such a structure is used, when the plastic pipe 1 is provided, the pitch between the engaging portions 1A of the interlock pipe 1 can be maintained at the neutral pitch length.

In this embodiment, two worms 1 are used.
Although 4 and 15 are arranged to face the outer circumference of the interlock tube 1 by 180 degrees, three or more worms may be arranged. When three worms are arranged, they are arranged at intervals of 120 degrees in the circumferential direction, and when four worms are arranged, they are arranged at intervals of 90 degrees in the circumferential direction. Is desirable.

The plastic tube extruder 12 is composed of a plastic material extrusion section 12A and a cross head 12B, and is arranged behind the engagement section pitch adjuster 11. The plastic material melted in the extrusion section 12A is the crosshead 1
The plastic pipe 3 is provided by being extruded and covered on the interlock pipe 1 inserted in 2B to form the flexible composite pipe A.

Depending on the structure of the flexible composite pipe A,
Before the plastic pipe 3 is provided on the interlock pipe 1, the plastic material is prevented from digging into the groove between the engaging portions 1A of the interlock pipe 1 and the space between the engaging portions 1A is provided on the interlock pipe 1. An intervening layer 8 such as a spiral of tape, a tape winding layer by vertical winding, or a resin extrusion buffer layer may be provided in order to suppress pitch deviation and prevent a decrease in the nipple temperature of the plastic tube extruder 12. In this case,
An interposing layer forming machine (not shown) is provided in place of the plastic pipe extruder 12 shown in FIG. In that case, the engaging portion pitch adjuster 11 is arranged on the front side of the interposing layer forming machine, and the pitch between the engaging portions of the interlock pipe 1 is adjusted to be equal to the neutral pitch length. . In this way, on the interlock pipe 1 provided with the intervening layer 8 on the outer periphery, a plastic pipe extruder 12 is provided longitudinally after the interposing layer forming machine, or is provided at a different place, so that the plastic material is Is extruded and coated to provide a plastic tube 3.

When the flexible composite pipe A is used for an electric wire pipe or a cable armor pipe, and is used for a fluid transport pipe having a simple structure, the main construction of the manufacturing apparatus is as described above. Further, when manufacturing the fluid transport pipe having the structure shown in FIG. 3, although not shown, a reinforcement layer forming machine for providing the metal reinforcement layer 4 on the plastic pipe 3 and a plastic outer sheath 7 are further provided. A sheath extruder is provided.

The flexible composite pipe manufacturing apparatus of the present invention has the above-described structure. This device is a worm 14, 1
The pitch between the engaging portions 1A of the interlock pipe 1 is adjusted so as to be equal to the neutral pitch length by using the engaging portion pitch adjuster 11 having 5 before the plastic pipe 3 is provided at the latest. The flexible composite pipe A having stable bending characteristics can be efficiently manufactured at low cost.

A method of manufacturing the flexible composite pipe A of the present invention using the manufacturing apparatus of the above embodiment will be described with reference to FIGS. 1 and 2 and, if necessary, FIGS. Is bent into an S-shape or a Z-shape to engage hooks 2A,
2B is formed, the metal tape 2 is spirally wound at a predetermined pitch, and the adjacent engaging hooks 2A and 2B are engaged with each other to form the spiral engaging portion 1A, thereby manufacturing the interlock pipe 1. Then, it is wound on a drum and supported by the feeding device 9.

Next, the interlock pipe 1 is fed from the feeding device 9 and supplied to the engaging portion pitch expanding device 10, where
The engaging portion 1A of the interlock tube 1 is stretched, for example, until the amount of extension becomes maximum, and the pitch between the engaging portions 1A is once made longer than the neutral pitch length.

Then, the engaging portion 1A of the interlock tube 1 is stretched to the maximum as described above, and the interlock tube 1 is engaged with the engaging portion 1A with the pitch between the engaging portions 1A longer than the neutral pitch length. It is supplied to the pitch adjuster 11, where the pitch between the engaging portions 1A is shortened and adjusted to be equal to the neutral pitch length.

Next, while maintaining the pitch between the engaging portions 1A of the interlock pipe 1 at the neutral pitch length, the interlock pipe 1 is supplied to the plastic pipe extruder 3 and placed on the interlock pipe 1. Extruded and coated with a plastic material such as nylon or high-density polyethylene to cover the plastic tube 3
To provide. When an intervening layer 8 such as a tape winding layer or a resin extrusion buffer layer is interposed between the interlock tube 1 and the plastic tube 3, the engaging portion 1A of the interlock tube 1 is provided.
In the state where the pitch between them is maintained at the neutral pitch length, before supplying the interlock pipe 1 to the plastic pipe extruder 13, the interlock pipe 1 is once supplied to an intervening layer forming machine (not shown) and the interposing layer 8 is provided.
And then the plastic tube extruder 12 disposed at a later stage of the interposing layer forming machine or at another place, the interposing layer 8
A plastic tube 3 is provided on the top.

Next, depending on the structure of the flexible composite tube, a metal reinforcing layer 4 is further provided thereon by a metal reinforcing layer forming machine, and an outer sheath 7 is provided by a sheath extruder, and if necessary, metal Inside the reinforcing layer 4, or the metal reinforcing layer 4 and the outer sheath 7
A flexible composite pipe A is manufactured by interposing an intervening layer 8 such as a tape winding layer and a resin extrusion buffer layer. Since the flexible composite pipe A is manufactured in this manner, the pitch between the engaging portions 1A of the interlock pipe 1 does not fluctuate and fluctuate, and the flexible composite pipe A has stable bending characteristics. Can be manufactured.

[0035]

As described above, according to the first aspect of the present invention.
According to the method for producing a flexible composite pipe described in, when a plastic material is extruded and coated on an interlock pipe to provide a plastic pipe at the latest, an unreasonable tension or compression force acts on the interlock pipe, Since the pitch between the engaging portions of the interlock pipe does not fluctuate and vary and the pitch between the engaging portions of the interlock pipe is maintained at a substantially neutral pitch length, it is possible to provide a flexure having stable bending characteristics. A composite composite tube can be manufactured.

According to the apparatus for manufacturing a flexible composite pipe according to the second aspect of the present invention, the engagement part pitch adjuster having a worm is used to engage the interlock pipe before the plastic pipe is provided at the latest. Since the pitch between the parts is adjusted to be equal to the neutral pitch length, it is possible to efficiently and inexpensively manufacture a flexible composite pipe having stable bending characteristics over the entire length.

According to the apparatus for manufacturing a flexible composite pipe according to the third aspect of the present invention, as a worm of the engaging portion pitch adjusting machine, it is engaged with the outer periphery of the worm shaft on the upstream side in the traveling direction of the interlock pipe. A worm with a spiral tooth having a pitch longer than the neutral pitch length between the joints and gradually decreasing from the upstream side to the downstream side so as to be equal to the neutral pitch length on the downstream side. Since it is used, it becomes possible to more smoothly adjust the pitch between the engaging portions of the interlock pipe to be equal to the neutral pitch length,
A flexible composite tube having more stable bending characteristics can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an apparatus for manufacturing a flexible composite pipe according to the present invention.

FIG. 2 is an explanatory view showing, in an enlarged manner, a usage state of an engagement portion pitch adjuster, which is a main portion of the manufacturing apparatus of FIG.

FIG. 3 is a partially cutaway perspective view of a flexible composite pipe used for fluid transportation.

4 is a partially enlarged cross-sectional view of an engaging portion of an interlock pipe in the flexible composite pipe of FIG.

[Explanation of symbols]

1 Interlock tube 1A engagement part 2 metal tape 2A engagement hook 2B engagement hook 3 plastic tubes 4 Metal reinforcement layer 5 Internal pressure reinforcement layer 6 Axial force reinforcement layer 7 External sheath 8 Intervening layer 9 Feeder 10 Engaging part pitch enlarger 10A endless track type take-off machine 10B endless track type take-off machine 11 Engagement part pitch adjuster 12 Plastic tube extruder 12A extrusion section 12B crosshead 13 Collection machine 14 worm 15 worms 16 worm shaft 17 spiral teeth 18 Drive source 19 Transmission means A flexible composite pipe P pitch P1 pitch P2 pitch

Claims (3)

[Claims] 1. An engaging hook is formed by bending both side edges of a metal tape into an S-shape or a Z-shape, and the metal tape is spirally wound at a predetermined pitch so that adjacent engaging hooks are engaged with each other. In the method for producing a flexible composite pipe, the plastic pipe is formed by extruding and covering a plastic material directly or through an intervening layer on the interlock pipe formed with a spiral engagement portion to form the interlock pipe. Before installing the plastic pipe on the pipe at the latest, stretch the engaging portion of the interlock pipe in the pipe axial direction so that the pitch between the engaging portions is greater than the neutral pitch length at which the extension amount and the contraction amount of the engaging portion are equal. Once the length of the engaging portion is shortened, the pitch of the engaging portion is shortened to be equal to the neutral pitch length, and the pitch of the engaging portion is maintained at the neutral pitch length. A method for producing a flexible composite pipe, characterized in that a plastic pipe is provided by extruding and covering a plastic material directly on the Cook pipe or through an intervening layer. 2. The engaging portion of the interlock pipe according to claim 1 is stretched in the pipe axial direction so that the pitch of the engaging portion is once longer than a neutral pitch length at which the extension amount and the contraction amount of the engaging portion are equal. Engagement part pitch expander, engagement part pitch adjuster that adjusts the pitch of the engagement part that is longer than the neutral pitch length to be equal to the neutral pitch length, and the pitch of the engagement part is neutral. And a plastic pipe extruder in which a plastic pipe is provided by extruding and covering a plastic material directly or via an intervening layer on an interlock pipe adjusted to a pitch length, wherein the engaging portion pitch adjusting machine is a worm shaft A plurality of worms with spiral teeth protruding on the outer periphery having a pitch equal to the neutral pitch length of the engaging part of the interlock pipe, and the worms are rotated according to the feeding speed of the interlock pipe. And a driving source for driving the plurality of worms, and the plurality of worms are rotatably arranged on the outer circumference of the interlock pipe so that the teeth of the worm bite into the gaps between the engaging portions of the interlock pipe. An apparatus for manufacturing a flexible composite pipe, which is characterized in that 3. The engaging portion of the interlock pipe according to claim 1 is stretched in the pipe axial direction so that the pitch of the engaging portion is once longer than a neutral pitch length at which the extension amount and the contraction amount of the engaging portion are equal. Engagement part pitch expander, engagement part pitch adjuster that adjusts the pitch of the engagement part that is longer than the neutral pitch length to be equal to the neutral pitch length, and the pitch of the engagement part is neutral. And a plastic pipe extruder in which a plastic pipe is provided by extruding and covering a plastic material directly or via an intervening layer on an interlock pipe adjusted to a pitch length, wherein the engaging portion pitch adjusting machine is a worm shaft The outer periphery has a pitch that is longer than the neutral pitch length between the engaging portions on the upstream side in the traveling direction of the interlock pipe, and gradually decreases from the upstream side to the downstream side so as to be equal to the neutral pitch length on the downstream side. Su It has a plurality of worms with spiral teeth protruding and a drive source that drives the worms to rotate in accordance with the feeding speed of the interlock pipe. An apparatus for manufacturing a flexible composite pipe, wherein the interlock pipe is rotatably arranged on the outer circumference of the interlock pipe so as to bite into the gap between the engaging portions.