JP2019105326A - Composite tube - Google Patents

Abstract

To provide a composite tube which enables smooth exposure of an end part of a tube body including a coating layer and an intermediate layer.SOLUTION: A composite tube 10 includes a tube body 12, an intermediate layer 14, and a coating layer 20 shown in Fig. 2. The coating layer 20 has a tubular form, covers an outer periphery of the tube body 12, is formed into a bellows shape by forming annular crest parts 22 protruding to the radial outer side and annular trough parts 24 recessed on the radial outer side alternately in an axial direction S of the tube body 12, guided by the outer periphery of the tube body 12, and can be shortened in the axial direction S. The intermediate layer 14 is disposed between the tube body 12 and the coating layer 20, is formed into a sheet form with the axial direction S set to its longitudinal direction and a direction intersecting with the axial direction S set to a shorter side direction, and has slits 14C which are disposed at a certain interval in a slit width direction with the shorter side direction set to a slit length direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a composite tube having a multilayer structure.

Patent Document 1 below discloses a composite pipe. The composite pipe comprises a tubular body, a lubricating layer covering the outer peripheral surface of the tubular body, a sheet-like member as an intermediate layer covering the outer peripheral surface of the lubricating layer, and a protective layer as a covering layer covering the outer peripheral surface of the sheet-like member Is equipped. The covering layer has flexibility, and irregularities are formed on the inner circumferential surface of the covering layer.
In a composite tube configured in this manner, the frictional resistance between the tube and the covering layer is small, and the end of the covering layer is urged toward the axial direction of the tube to expose the end of the tube from the covering layer it can. For this reason, at the time of piping work, such as connecting a compound pipe to a pipe joint, work efficiency can be improved.

JP, 2013-231490, A

  In the above composite tube, the end of the covering layer can be pushed close to expose the tube, but the end of the covering layer is smoothly pushed close including the end of the intermediate layer to expose the end of the pipe There was room for improvement.

  In view of the above facts, the present invention provides a composite tube that can smoothly expose the end of the tube including the covering layer and the intermediate layer.

  The composite pipe according to the first aspect of the present invention comprises a tubular body, a tubular tubular portion covering an outer periphery of the tubular body, and an annular peak portion convex outward in the radial direction and an annular valley concave in the radial outer side Between the tube and the cover layer, which are alternately formed along the axial direction of the tube and are corrugated and guided along the outer periphery of the tube so that they can be shortened along the axial direction Formed in a sheet shape having the axial direction as the longitudinal direction and the direction intersecting the axial direction as the lateral direction, the lateral direction as the slit length direction, and at a constant interval in the slit width direction And an intermediate layer having a plurality of slits.

  The composite tube according to the first aspect comprises a tube, a covering layer, and an intermediate layer. The covering layer is tubular and configured to cover the outer periphery of the tube. The intermediate layer is disposed between the tubular body and the covering layer, and formed in a sheet shape having an axial direction as a longitudinal direction and a direction intersecting the axial direction as a lateral direction.

Here, the covering layer is in the form of a bellows in which an annular peak that is convex outward in the radial direction and an annular valley that is concave in the outer radial direction are alternately formed along the axial direction of the tube. Ru. For this reason, since the covering layer is configured to be easily deformed along the axial direction of the tube, it is guided along the outer periphery of the tube and can be shortened along the axial direction, and the end of the tube is smoothly It can be exposed.
In addition, the intermediate layer has a slit. A plurality of slits are provided with the short direction of the intermediate layer as the slit length direction, and a plurality of slits at a constant interval in the slit width direction. For this reason, in the intermediate layer, the slit portion is easily deformed along the axial direction of the tube, so the end of the intermediate layer can be shortened in the axial direction while being guided by the outer periphery of the tube. The end of the tube can be exposed.

  In the composite tube according to the second aspect of the present invention, in the composite tube according to the first aspect, the slit is disposed on the cover layer side of the intermediate layer.

  According to the composite tube of the second aspect, the slits are provided on the coating layer side of the intermediate layer, so that the valleys of the coating layer and the slits of the intermediate layer can be easily engaged. Therefore, the covering layer is shortened and deformed along the axial direction of the tube, and the intermediate layer is shortened and deformed along the axial direction of the tube following the covering layer, and the end of the tube is exposed smoothly. It can be done.

  In the composite tube according to the third aspect of the present invention, in the composite tube according to the first aspect or the second aspect, the slits are disposed on the cover layer side of the intermediate layer and are made to coincide with the arrangement intervals in the axial direction of the valleys It is formed in the cross-sectional shape where the radial direction outer side becomes concave.

  According to the composite pipe relating to the third aspect, the slits are disposed on the coating layer side of the intermediate layer, and the slits are formed on the radially outer side of the intermediate layer so that the slits coincide with the arrangement interval in the axial direction of the valleys of the coating layer. It forms in the cross-sectional shape which becomes. As a result, the engagement between the ridges of the cover layer and the projections between the slits in the intermediate layer is further promoted, so that the cover layer is deformed along the axial direction of the tube, and the cover layer follows the cover layer. As a result, the intermediate layer is shortened along the axial direction of the tube, and the end of the tube can be exposed more smoothly.

  In the composite tube according to the fourth aspect of the present invention, in the composite tube according to any one of the first to third aspects, the slit length direction of the slit is 45 degrees or more in absolute value with respect to the axial direction. It agrees with the direction which makes an angle less than a degree.

  According to the composite pipe of the fourth aspect, since the slit length direction of the slit coincides with the direction forming an angle of 45 degrees or more and 135 degrees or less in absolute value with respect to the axial direction of the pipe body Thus, the amount of shortening deformation along the axial direction of the intermediate layer can be increased.

  In the composite tube according to the fifth aspect of the present invention, in the composite tube according to the first aspect, the slit is disposed on the tube side of the intermediate layer.

  According to the composite pipe relating to the fifth aspect, since the slit is disposed on the tube side of the intermediate layer, the intermediate layer is easily deformed along the axial direction, and the covering layer and the intermediate layer are axially aligned at the end of the tube. It can be easily shortened and deformed along the direction.

  According to the present invention, it is possible to provide a composite tube that can smoothly expose the end of the tube including the covering layer and the intermediate layer.

It is a perspective view showing the compound tube end concerning a 1st embodiment of the present invention. FIG. 2 is a side view with a partial cross section of the composite tube end shown in FIG. 1; It is an expanded sectional view which expands and shows the principal part of the compound pipe end shown by FIG. It is a perspective view of the middle class which constitutes a compound tube shown in Drawings 1-3. It is a schematic block diagram of the manufacturing apparatus which manufactures the composite pipe shown by FIG. It is a perspective view corresponding to FIG. 1 which shows the state which exposed the composite tube end part. It is a side view corresponding to FIG. 2 which shows the state which exposed the composite tube end part. It is an expanded sectional view corresponding to Drawing 3 in the 1st operation process showing the operation state of shortening modification of a compound tube end. It is an expanded sectional view corresponding to Drawing 3 in the 2nd operation process. It is a side view which has a partial cross section corresponding to FIG. 2 which shows the composite pipe end part which concerns on 2nd Embodiment of this invention.

Hereinafter, a plurality of embodiments which are an example of a composite pipe according to the present invention will be described in detail with reference to the drawings as appropriate. Constituent elements indicated with the same reference numerals in the respective drawings mean identical constituent elements or substantially identical constituent elements, and redundant description in the embodiments will be omitted.
The present invention is not limited to the following embodiments, and can be appropriately changed without departing from the scope of the present invention.

Here, in the description of the embodiment, a numerical range represented by using a symbol “to” means a range including numerical values described before and after the symbol “to” as a lower limit value and an upper limit value.
In addition, "process" is used not only for an independent process but also for "part of a process" that can not be clearly distinguished from other processes but can achieve the same function.
Further, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless a plurality of substances corresponding to each component are present in the composition. Do.
Furthermore, "main component" means a component having the highest content by mass in the mixture, unless otherwise specified.

(First embodiment)
A composite pipe according to a first embodiment of the present invention will be described using FIGS. 1 to 9.
[Overall Configuration of Composite Pipe 10]
As shown in FIG. 1 and FIG. 2, the composite tube 10 according to the present embodiment includes a tube 12, a covering layer 20 which is tubular and covers the outer periphery of the tube 12, a tube 12 and a covering layer 20. And an intermediate layer 14 disposed therebetween.

(1) Configuration of Tube 12 The tube 12 is a cylindrical tube and is a resin tube formed using a resin material. Examples of the resin as the resin material include polyolefins such as polybutene, polyethylene, crosslinked polyethylene, and polypropylene, and vinyl chloride. The resin may be used alone or in combination of two or more. Among the resins, polybutene is suitably used, and it is preferable to contain polybutene as a main component. For example, it is more preferable to contain 85 mass% or more of polybutene in the resin material which comprises the tubular body 12.
Moreover, the resin material which comprises the tubular body 12 may contain other additives.

The outer diameter of the tubular body 12 is not particularly limited, but is set, for example, in the range of 10 mm to 100 mm. The most preferred outer diameter of the tube 12 is in the range of 12 mm to 35 mm.
Moreover, the thickness of the tubular body 12 is not particularly limited, but is set to, for example, 1.0 mm to 5.0 mm. The most preferred thickness of the tube 12 is in the range of 1.4 mm to 3.2 mm.

(2) Configuration of Covering Layer 20 The covering layer 20 has a cylindrical tubular shape which is slightly larger than the outer diameter of the tubular body 12 and is disposed with the intermediate layer 14 interposed in the tubular body 12. The covering layer 20 is a resin pipe formed using a resin material. Examples of the resin as the resin material include polyolefins such as polybutene, polyethylene, polypropylene, and crosslinked polyethylene, and vinyl chloride. The resin may be used alone or in combination of two or more. Among the resins, low density polyethylene is suitably used, and it is preferable to contain low density polyethylene as a main component. For example, the resin material constituting the covering layer 20 preferably contains 80% by mass or more, more preferably 90% by mass or more of low density polyethylene.

Moreover, it is preferable to set MFR (Melt Flow Rate) of resin used for the coating layer 20 to 0.25 or more, and it is more preferable to set to 0.3 or more. More preferably, the MFR is set in the range of 0.35 to 1.2. When the MFR is set to 0.25 or more, the resin of the cover layer 20 can easily enter the intermediate layer 14 and the adhesion between the cover layer 20 (particularly, the valley portion 24 described later) and the intermediate layer 14 can be enhanced. .
Moreover, when MFR is set to 1.2 or less, it becomes difficult to generate | occur | produce a burr | flash at the time of shaping | molding of the coating layer 20. As shown in FIG.
In addition, in the resin material which comprises the coating layer 20, the other additive may be contained.

  As shown in FIG. 2, the covering layer 20 includes an annular peak 22 that is convex outward in the radial direction R and an annular valley 24 that is concave in the outer side in the radial direction R of the tube 12. They are formed alternately and continuously along the axial direction S. That is, the covering layer 20 is configured in a bellows shape. The ridges 22 are arranged outside the valleys 24 in the radial direction R.

  The cross-sectional structure of the covering layer 20 will be described in detail with reference to FIG. The outermost portion in the bellows-like radial direction R of the covering layer 20 is an outer wall (top wall) 22A, and the innermost portion in the radial direction R is an inner wall 24A. The outer side of the radial direction R is a peak 22 and the inner side of the radial direction R is a valley 24 with the middle portion M between the outer wall 22A and the inner wall 24A in the radial direction R as a boundary.

The ridges 22 are a pair of an outer wall 22A extending in the axial direction S (see FIG. 2) and a pair extending inward in the radial direction R from both ends in the axial direction S of the outer wall 22A. And a side wall 22B. Between the outer side wall 22A and the side wall 22B, there is formed an arc-shaped outer bent portion 22C which protrudes outward in the radial direction R.
The valley portion 24 includes an inner side wall 24A extended along the axial direction S (see FIG. 2), and a pair of side walls 24B extended outward in the radial direction R from both ends of the inner side wall 24A. Have. Between the inner side wall 24A and the side wall 24B, an arc-like inward bent portion 24C which protrudes inward in the radial direction R is formed.

  Inside the radial direction R of the ridge 22 of the covering layer 20, a concave mountain space 23 is formed by surrounding the outer side of the radial direction R and one and the other of the axial directions S by the outer wall 22A and the pair of side walls 22B. It is formed. A part of the outside in the radial direction R of the intermediate layer 14 is engaged with the mountain space 23.

Further, in the present embodiment, the length L1 of the ridge portion 22 in the axial direction S is set longer than the length L2 of the valley portion 24 in the axial direction S. Here, the length L1 of the ridge portion 22 is a distance between the outer surfaces of the pair of side walls 22B on the line of the middle portion M, as shown in FIG. On the other hand, the length L2 of the valley portion 24 is the distance between the inner surfaces of the pair of side walls 24B on the line of the middle portion M. The length L1 is set to 1.2 times or more of the length L2, and when the end of the covering layer 20 is pressed and shortened along the axial direction S, compared with the inner side wall 24A of the valley portion 24, The outer side wall 22A of the mountain portion 22 is configured to be easily deformed.
The length L2 is preferably set to 0.8 mm or more. If the length L2 is less than 0.8 mm, the width of the valleys 24 is too small, and after extrusion, the portion corresponding to the valleys 24 of the mold when forming unevenness with the mold to produce the covering layer 20 is Thin and fragile, difficult to form. Further, the length L1 is preferably 5 times or less of the length L2. The flexibility of the composite tube 10 can be maintained by setting the length L1 to 5 times or less the length L2. In addition, when the length L1 is too long, when laying the composite pipe 10, the contact area with the ground becomes large and the construction becomes difficult.

The thinnest part of the thickness of the covering layer 20 is set to 0.1 mm or more, and the thickest part is set to 0.4 mm or less. When the thickness is set to such a thickness, the end portion of the covering layer 20 is easily pushed along the axial direction S so as to be easily shortened and deformed.
The thickness H1 of the outer side wall 22A is set to be thinner than the thickness H2 of the inner side wall 24A, and is set to not more than 0.9 times the thickness H2 here. When set to such a thickness, the outer wall 22A is more easily deformed than the inner wall 24A, so that the end portion of the covering layer 20 is easily pushed along the axial direction S to be shortened and deformed.

  The radius difference ΔR between the outer surface in the radial direction R of the ridges 22 and the outer surface in the same direction of the valleys 24 is set to 800% or less of the average of the thickness of the covering layer 20. If the radius difference ΔR is too large, the portion (outer wall 22A) along the axial direction S of the ridge 22 is difficult to deform during shortening and deformation, and additionally, the valley 24 bulges outward in the radial direction R The adjacent mountain portions 22 do not come close to each other, so that they are likely to be in a distorted deformation state. In the case where the radius difference ΔR is set to 800% or less of the average of the thickness of the covering layer 20, the length in the axial direction S of the ridges 22 is set longer than the length in the axial direction S of the valleys 24. Thus, the deformation state can be effectively suppressed. The setting of the length in the axial direction S of the ridge portion 22 is effective when the radius difference ΔR is set to 600% or less.

  Although the diameter (outer diameter of the outermost part) of the coating layer 20 is not specifically limited, For example, it is set to the range of 13 mm-130 mm.

(3) Configuration of Intermediate Layer 14 As shown in FIG. 4, the intermediate layer 14 is formed in a sheet shape having the axial direction S as the longitudinal direction and the direction intersecting with the axial direction S as the lateral direction, It is a resin layer which has a porous structure formed using resin material. In the intermediate layer 14, the length (width) in the short direction is set to be approximately equal to the outer peripheral length of the tube 12, and the length in the longitudinal direction of the intermediate layer 14 is set approximately equal to the length in the axial direction S of the tube 12. It is made into a belt shape. As shown in FIGS. 2 to 4, in the natural state, the intermediate layer 14 has a plurality of convex portions formed between the sheet-like intermediate layer main body 14A, the plurality of slits 14C, and the adjacent slits 14C. And 14B. The natural state means a state in which no external force such as compressive stress or tensile stress is applied under a certain environment. The constant environment is, for example, an environment with a temperature of 23 ° C. and a relative humidity of 45%. The slits 14C are disposed on the surface portion of the middle layer main body 14A on the side of the covering layer 20, that is, on the outer side of the radial direction R here.

Describing in detail, the slits 14C have the short side direction of the intermediate layer main body 14A as the slit length direction, and are disposed at constant intervals in the slit width direction. Assuming that the axial direction S of the tubular body 12 is a reference, the slit length direction of the slit 14C intersects the axial direction S on the plane of the intermediate layer main body 14A, and the slit width direction coincides with the axial direction S is there. In the cross section in the thickness direction of the intermediate layer main body 14A, the slit 14C is formed in a V-shaped or U-shaped cross-sectional shape in which the outer side in the radial direction R is opened and the inner side in the radial direction R is closed. As a result, the slits 14C are formed as valleys in which the outer surface portion of the intermediate layer main body 14A in the radial direction R is recessed. In the present embodiment, the depth of the slit 14C is set in the range of 0.3 times to 0.7 times the thickness of the intermediate layer main body 14A. When the depth of the slit 14C is less than 0.3 times, the depth of the slit 14C becomes shallow and it becomes difficult to shorten and deform along the axial direction S. In addition, when the depth of the slit 14C exceeds 0.7 times, the depth of the slit 14C becomes deep, and the intermediate layer main body 14A is likely to be broken starting from the slit 14C.
The convex portion 14B is disposed between the slits 14C adjacent in the slit width direction. The convex portion 14B is formed in a cross-sectional shape of an inverted V-shape or an inverted U-shape which protrudes outward in the radial direction R with respect to the slit 14C.
Further, the entire cross-sectional shape of the intermediate layer main body 14A including the slit 14C and the convex portion 14B may be a sine wave shape or a rectangular wave shape. Furthermore, the slit 14C may be a cut formed by a cutter.

As shown in FIG. 4, the slit length direction of the slit 14 </ b> C coincides with the axial direction S in the direction forming the angle α. In the present embodiment, the angle α is made to coincide with the direction forming an absolute value of 90 degrees, and the amount of shortening by which the intermediate layer 14 is shortened and deformed by the slit 14C is set to the maximum. There is.
If the angle α is set in the range of 45 degrees to 135 degrees in absolute value, the shortening amount of the intermediate layer 14 can be sufficiently increased.

Furthermore, as shown in FIG. 4, the arrangement pitch P of the slits 14C in the slit width direction (axial direction S) is made to coincide with the pitch of the valleys 24 in the same direction of the covering layer 20, as shown in FIG. ing.
Thereby, the portion of the slit 14C of the intermediate layer 14 is compressed and held in the radial direction R between the outer surface of the tubular body 12 in the radial direction R and the inner side wall 24A of the valley portion 24. In addition, the convex portion 14B between the slits 14C of the intermediate layer 14 enters the peak space 23 of the peak portion 22 of the cover layer 20, and is axially directed to the pair of side walls 22B of the peak portion 22 and the pair of side walls 24B of the valley portion 24. It is compressed and held at S and locked in the axial direction S.

Resins as the intermediate layer 14 include, for example, polyurethane, polystyrene, polyethylene, polypropylene, and ethylene propylene diene rubber, and mixtures of these resins. Among the resins, polyurethane is preferred.
The intermediate layer 14 is preferably a layer containing polyurethane as a main component (that is, a porous urethane layer). For example, it is preferable to contain 80 mass% or more of polyurethane in the component of the intermediate | middle layer 14, and it is more preferable to contain 90 mass% or more. The porous resin layer as the intermediate layer 14 may contain other additives.

  The abundance ratio of pores in the mid layer 14 (for example, the foaming ratio in the case of a foam) can be measured using the method described in Appendix 1 of JIS-K6400-1 (2012). Here, the abundance ratio is preferably 25/25 mm or more, and more preferably 45/25 mm or less. The mid layer 14 is preferably a foam.

The density of the porous resin layer as the intermediate layer 14 is set in a range of ^{12kg / m 3 ~22kg / m 3} .
In the composite pipe 10, when connecting a joint or the like to the end of the inner pipe 12, the end of the covering layer 20 is shortened, deformed and shifted along the axial direction S, and the end of the pipe 12 is exposed. Ru. At this time, the displacement in the axial direction S of the intermediate layer 14 does not follow the shortened and deformed covering layer 20, and the intermediate layer 14 is left on the outer surface of the tube 12, and the end of the tube 12 is sufficiently It may not be exposed.
Therefore, by setting the density of the porous resin layer to 22 kg / m ³ or less, the intermediate layer 14 has appropriate flexibility, and the end portion of the covering layer 20 is shortened and deformed, and the end portion of the tubular body 12 In exposing the intermediate layer 14, the intermediate layer 14 can well follow the sticking of the end of the covering layer 20, and the leaving of the intermediate layer 14 to the outer surface of the tubular body 12 can be suppressed. As a result, the end of the tube 12 can be easily exposed.
On the other hand, by setting the density of the porous resin layer to 12 kg / m ³ or more, the intermediate layer 14 has appropriate strength, and breakage or breakage of the intermediate layer 14 at the time of processing such as production of the composite pipe 10. The occurrence can be effectively suppressed.
Here, the density of the porous resin layer can be measured by the method prescribed in JIS-K7222 (2005). The measurement environment is a temperature of 23 ° C. and a relative humidity of 45%.

  The method of controlling the density of the porous resin layer in the above range is not particularly limited, but, for example, a method of adjusting the existing ratio of pores (for example, the foaming ratio in the case of a foam), resin And the like. As a method of adjusting the molecular structure of the resin, it is possible to practically use a method of adjusting the molecular structure of the monomer serving as a raw material of the resin and the cross-linked structure thereof.

The thickness of the intermediate layer main body 14A in the natural state of the intermediate layer 14, that is, the dimension from the highest position of the convex portion 14B of the intermediate layer main body 14A to the back surface of the intermediate layer main body 14A on the tube 12 side is 1 mm to 20 mm. It is set in the range of According to the intermediate layer 14 set in this thickness range, the slit 14C compressed and held between the inner side wall 24A of the covering layer 20 and the tubular body 12 can be easily formed.
The thickness of the intermediate layer main body 14A is preferably set in the range of 2 mm to 15 mm, and more preferably in the range of 2.5 mm to 10 mm.
Here, the thickness in the natural state of the intermediate layer main body 14A is obtained by measuring any three places of the intermediate layer main body 14A in the state before being wound around the tubular body 12 and before forming the covering layer 20. It is taken as the average value. Further, the thickness of the intermediate layer main body 14A in the natural state is obtained by measuring the arbitrary three portions of the intermediate layer main body 14A after a predetermined time has elapsed after taking out the intermediate layer 14 from the manufactured composite tube 10 and restoring it from the compressed state. The average value of the values obtained by

  The length of the axial direction S in the natural state of the mid layer 14 extracted from between the tube body 12 and the coating layer 20 is set to be in the range of 90% to 100% of the length of the axial direction S of the coating layer 20 There is. When the length of the intermediate layer 14 is set in this manner, the intermediate layer 14 is not held in a stretched state between the tube body 12 and the covering layer 20, so when the covering layer 20 is shortened and deformed. The relative movement between the intermediate layer 14 and the covering layer 20 is less likely to occur. Therefore, the intermediate layer 14 and the cover layer 20 can be easily shortened and deformed along the axial direction S, so that the end of the tubular body 12 can be easily exposed.

[Method of Manufacturing Composite Pipe 10]
The method of manufacturing the composite pipe 10 according to the present embodiment is as follows. First, the intermediate layer 14 having the slits 14C and the projections 14B is formed on the outer surface of the sheet-like intermediate layer main body 14A in the radial direction R. The slits 14C and the projections 14B are formed on the outer surface of the intermediate layer main body 14A using a thermocompression bonding method in which a thermocompression bonding roller (not shown) is rolled. As the thermocompression bonding roller, a thermocompression bonding roller is used in which a convex portion for compression molding the slit 14C and a concave portion for compression molding the convex portion 14B are alternately arranged in the circumferential direction.
Further, the intermediate layer 14 may be formed by a cutting method using a wave-like cutter that forms the slit 14C and the convex portion 14B.

  In the method of manufacturing the composite tube 10, the intermediate layer 14 in which the slits 14C are formed in advance is wound around the outer surface of the tubular body 12 in the radial direction R such that the slits 14C are on the outer side of the radial direction R; Forming the coating layer 20 on the outer surface in the radial direction R of

For example, a manufacturing apparatus 30 shown in FIG. 5 is used to manufacture the composite pipe 10. The manufacturing apparatus 30 is configured to include an extruder 32, a die 34, a wave mold 36, a cooling tank 38, and a pulling device 39. The right side of the manufacturing apparatus 30 shown in FIG. 5 is the upstream side in manufacturing, and the left side of the manufacturing apparatus 30 is the downstream side in manufacturing. The composite pipe 10 is manufactured by moving the pipe body 12 from the right side to the left side of the manufacturing apparatus 30, winding the intermediate layer 14 around the pipe body 12 in the process of movement, and forming the covering layer 20 on the intermediate layer 14. It is done.
In the manufacturing apparatus 30, when the moving direction of the pipe body 12 is made to be the manufacturing direction Y from the upstream side to the downstream side, each of the die 34, the wave applying mold 36, the cooling tank 38 and the pulling device 39 is in the manufacturing direction Y It is arranged sequentially. The extruder 32 is disposed above the die 34.

  Further upstream of the die 34, a sheet-like member 14S wound up in a roll shape, which is not shown, which is a tube 12 and an intermediate layer 14 is disposed. When the composite pipe 10 located on the downstream side of the manufacturing apparatus 30 is pulled in the manufacturing direction Y using the pulling device 39, each of the tube 12 and the sheet-like member 14S (intermediate layer 14) is upstream of the manufacturing apparatus 30. It is continuously supplied from The sheet-like member 14S is wound around the entire circumference of the outer surface in the radial direction R of the supplied tubular body 12 in front of the die 34, and the intermediate layer 14 is formed. Since the sheet-like member 14S is supplied to the die 34 with slack before the die 34, no tensile stress is generated in the intermediate layer 14.

  On the outer surface of the intermediate layer 14 in the radial direction R, the resin material 20A (melt of the resin composition forming the covering layer 20) melted from the die 34 is extruded in a cylindrical shape and applied. The resin material 20A used here is made of low density polyethylene (LDPE) having an MFR of 0.25 or more, so it becomes easy to enter the pores (air bubbles) of the intermediate layer 14. Thereby, the adhesiveness of middle class 14 and resin material 20A can be improved.

  When the tubular extruded body 21 in which each of the tubular body 12, the intermediate layer 14, and the resin material 20A is laminated is formed from the inside to the outside in the radial direction R, the corrugated die disposed on the downstream side of the die 34 Using the step 36, the step of applying a wave to the resin material 20A (step of forming a bellows shape) is performed. The corrugating mold 36 is constituted of, for example, a pair of left and right molds, and each mold is provided with a semicircular inner surface. On the inner surface of the mold, a concave forming portion 36A for forming the peak portion 22 in a portion corresponding to the peak portion 22 of the covering layer 20 and a convex shape for forming the valley portion 24 in a portion corresponding to the valley portion 24 The portions 36B are alternately provided along the manufacturing direction Y. That is, the inner surface of the corrugated mold 36 is formed in a bellows shape opposite to that of the covering layer 20. In the corrugated die 36, a suction hole 36C, one end of which is in communication with the molding portion 36A and the other end of which is connected to a suction device (not shown), is provided. The suction device is configured to suck the inside of the cavity formed by the forming portion 36A through the suction hole 36C.

  On the downstream side of the die 34, the corrugated die 36 is made to approach the resin material 20A from the left and right two directions so that the inner surfaces of the pair of dies come in contact with the resin material 20A. Then, the wave applying mold 36 covers the outer periphery of the tubular extruded body 21 and compresses the resin material 20A while compressing the resin material 20A by the forming portion 36B, and forms the tubular extruded body 21 together with the tubular body 12 and the intermediate layer 14. Move in the manufacturing direction Y. At this time, the inside of the cavity formed by the forming portion 36A of the wave application mold 36 is sucked through the suction holes 36C by a suction device (not shown) to be a negative pressure. Thereby, the resin material 20A is deformed toward the outside in the radial direction R and is formed by the forming portion 36A, and a bellows in which the ridges 22 and the valleys 24 are alternately arranged along the axial direction S from the resin material 20A. The cover layer 20 is formed.

  Here, although the convex portion 14B of the intermediate layer 14 is originally formed in a cross-sectional shape that protrudes outward in the radial direction R, when the resin material 20A is deformed to the outer side in the radial direction R in the molding portion 36A. It penetrates deeply into the mountain space 23 (see the partial enlarged view shown in FIG. 4) and is locked. The slit 14C portion of the intermediate layer 14 is bonded to the inner side wall 24A of the valley portion 24 of the cover layer 20, and is compressed and held between the inner side wall 24A and the tubular body 12.

  When the coating layer 20 is formed into a bellows shape using the wave application mold 36, the coating layer 20 is cooled using the cooling tank 38, and the bellows-shaped coating layer 20 is completed, and the composite tube 10 is manufactured. . The composite pipe 10 is continuously conveyed in the manufacturing direction Y by using the pulling device 39, and the manufacturing pipe 30 continuously manufactures the composite pipe 10.

[Operation and effect of the present embodiment]
As shown in FIGS. 1 to 3, the composite tube 10 according to the present embodiment includes a tube body 12, a covering layer 20, and an intermediate layer 14. The covering layer 20 is tubular and configured to cover the outer periphery of the tube 12. The intermediate layer 14 is disposed between the tubular body 12 and the covering layer 20, and is formed in a sheet shape having the axial direction S as the longitudinal direction and the direction intersecting with the axial direction S as the lateral direction.

Here, as shown in FIG. 3, in the covering layer 20, the annular peak 22 that is convex toward the outer side in the radial direction R and the annular valley 24 that is concave in the outer side in the radial direction R The bellows are alternately formed along the axial direction S of 12. For this reason, as shown in FIGS. 6 and 7, the covering layer 20 is configured to be easily deformed from the left side to the right side along the axial direction S of the pipe body 12, so the pipe body 12 is And can be shortened in the axial direction S. Thereby, the end of the tube 12 can be exposed smoothly. Each of FIG. 8 and FIG. 9 shows the cross-sectional shape of the covering layer 20 which is successively shortened and deformed along the axial direction S.
In addition, the intermediate layer 14 has a slit 14C as shown in FIGS. 3 and 4. The slits 14C have a plurality of slits 14C, with the short direction of the intermediate layer 14 as the slit length direction, and at a constant interval in the slit width direction. Since the middle layer 14 includes the slits 14C, the thickness (cross-sectional area) of the slit 14C in the middle-layer main body 14A is smaller than the thickness (cross-sectional area) of the convex 14B. For this reason, in the intermediate layer 14, the slit 14C portion is easily deformed along the axial direction S of the tube 12. Therefore, the intermediate layer 14 can be shortened in the axial direction S while being guided by the outer periphery of the tube 12. It is assumed. Thereby, the end of the tube 12 can be exposed smoothly. Each of FIG. 8 and FIG. 9 shows the cross-sectional shape of the intermediate layer 14 which is sequentially shortened and deformed along the axial direction S.
Therefore, it is possible to provide the composite tube 10 that can smoothly expose the end of the tube 12 including the covering layer 20 and the intermediate layer 14.

  Further, in the composite pipe 10, as shown in FIG. 3, FIG. 8 and FIG. 9, the slits 14C are disposed on the cover layer 20 side of the intermediate layer 14, so the valleys 24 of the cover layer 20 and the intermediate layer It becomes easy to engage with the 14 slits 14C. Explaining in detail, the slit 14C is formed in a cross-sectional shape that is concave toward the inside in the radial direction R (the tube 12 side) on the surface portion of the intermediate layer main body 14A on the coating layer 20 side. Is formed in a cross-sectional shape which is convex inward in the radial direction R. That is, the valley portion 24 is inserted into the slit 14C. Therefore, the covering layer 20 is shortened and deformed along the axial direction S of the tube 12, and the intermediate layer 14 is shortened and deformed along the axial direction S of the tube 12 so as to follow the covering layer 20 and smoothly The end of the tube 12 can be exposed.

Further, in the composite pipe 10, as particularly shown in FIG. 3, the slits 14C are disposed on the side of the cover layer 20 of the intermediate layer 14 to match the arrangement interval in the axial direction S of the valleys 24 of the cover layer 20. The slits 14C are formed in a cross-sectional shape in which the outer side of the intermediate layer 14 in the radial direction R is concave.
Explaining in detail, the pitch in the axial direction S of the valleys 24 of the covering layer 20 is a value obtained by adding the length L1 in the axial direction S of the ridges 22 of the covering layer 20 and the length L2 in the same direction of the valleys 24. It becomes. On the other hand, the slits 14C are set to have a pitch P in which the slit width direction matches the axial direction S and the pitch of the valleys 24 matches. If it changes expression, the pitch of convex part 14B of middle class 14 will be made to correspond with the pitch of peak part 22 of covering layer 20, and convex part 14B will be considered as composition deep to peak space 23 of peak part 22.
For this reason, engagement with convex part 14B between peak part 22 of covering layer 20 and slit C of middle class 14 is promoted further. As a result, as shown in FIGS. 8 and 9, the covering layer 20 is shortened and deformed along the axial direction S of the tube 12 and the intermediate layer 14 follows the covering layer 20 in the axial direction of the tube 12. By shortening and deforming along the direction S, the end of the tube 12 can be exposed more smoothly.

  Further, in the composite pipe 10, as shown in FIG. 4, the slit length direction of the slit 14C of the intermediate layer 14 forms an angle α of 45 degrees to 135 degrees in absolute value with respect to the axial direction S of the tube 12. Be consistent with the direction. When exposing the end of the composite tube 10, a force along the axial direction S acts on the intermediate layer 14. At this time, the amount of shortening deformation along the axial direction S of the intermediate layer 14 can be made larger than the angle other than the angle α.

In addition, according to the composite pipe 10 according to the present embodiment, the following operation and effect can be obtained.
When the composite pipe 10 is connected to, for example, a pipe joint (not shown), the covering layer 20 is shortened in the axial direction S with respect to the covering layer 20 whose end is not exposed as shown in FIGS. Then, as shown in FIGS. 6 and 7, the force in the direction of exposing the end of the tube 12 is applied. As shown in FIG. 3, in the covering layer 20, when comparing the outer side wall 22A of the peak 22 and the inner side wall 24A of the valley 24, the length L1 of the axial direction S of the outer side wall 22A is the length of the inner side wall 24A. The thickness H1 of the outer side wall 22A is set to be smaller than the thickness H2 of the inner side wall 24A. In particular, the length L1 of the outer side wall 22A is set to 1.2 or more times the length L2 of the inner side wall 24A. Furthermore, the thickness of the covering layer 20 is set to 0.1 mm to 0.4 mm. Therefore, the outer side wall 22A is more easily deformed than the inner side wall 24A, and as shown in FIG. 8, the outer side wall 22A bulges outward in the radial direction R and deforms.
When the force is continuously applied, as shown in FIG. 9, in the covering layer 20, the adjacent peak portions 22 come close to each other, and the outer bending portion 22C of the peak portion 22 is deformed inward from this portion, and The inward bending portion 24C of the valley portion 24 is deformed inward from this point. For this reason, as shown in FIGS. 6 and 7, at the end of the composite pipe 10, a part of the covering layer 20 moves in the direction in which the pipe body 12 is exposed.
At this time, in the intermediate layer 14, as shown in FIG. 3, the slit 14C portion of the intermediate layer main body 14A is in close contact with the valley portion 24 of the covering layer 20, and the convex portion 14B of the intermediate layer main body 14A is adjacent to the covering layer 20. It is engaged between the side walls 24B of the matching valleys 24. For this reason, as shown in FIGS. 8 and 9, the intermediate layer 14 is shortened and deformed along with the shortened deformation of the covering layer 20, so that the end of the tube 12 is secured as shown in FIGS. Can be exposed to

  Further, in the composite pipe 10, as shown in FIG. 8 and FIG. 9, when the covering layer 20 is shortened and deformed, the outer wall 22A bulges and deforms at the ridges 22 of the covering layer 20. For this reason, the valley portion 24 may bulge outward in the radial direction R even if the bending angle of the outer bending portion 22C of the covering layer 20 or the bending angle of the inner bending portion 24C or the thickness of the outer wall 22A etc. It can suppress that the adjacent peak part 22 comrades do not approach and it will be in a distorted deformation state. Thereby, the fall of the external appearance of the edge part of the coating layer 20 shortened and deformed can be suppressed effectively.

  In the present embodiment, in the covering layer 20 shown in FIG. 3, the thickness H1 of the outer side wall 22A is set smaller than the thickness H2 of the inner side wall 24A, but the thickness H1 of the outer side wall 22A is It may be set to the same degree as the thickness H2 of the inner side wall 24A.

  Further, in the present embodiment, in the covering layer 20 shown in FIG. 3, the cross-sectional shape of the outer side wall 22A is formed in a substantially linear shape along the axial direction S, but becomes convex outward in the radial direction R. The cross-sectional shape of the outer side wall 22A may be formed in an arc shape. In the coating layer 20 configured in this manner, the outer side wall 22A bulges outward in the radial direction R and is easily deformed. In the valley portion 24 of the covering layer 20, the inner side wall 24A may be formed into an arc-shaped cross-sectional shape which is convex inward in the radial direction R.

  Further, in the present embodiment, in the composite pipe 10 shown in FIG. 3, the surface on the tube 12 side of the middle layer main body 14A of the intermediate layer 14 is a flat surface, and substantially the entire outer peripheral surface of the tube 12 is It is touched. When the intermediate layer 14 and the covering layer 20 are relatively moved along the axial direction S with respect to the tube 12 at the end of the composite tube 10, as shown in FIGS. 6 and 7, the end of the tube 12 Is exposed. Since the frictional force between the outer peripheral surface of the tubular body 12 and the surface of the intermediate layer 14 on the tubular body 12 side is large, the intermediate layer 14 and the covering layer 20 are held at the shortened and deformed position, and it is difficult to easily return.

  Further, in the present embodiment, in the composite tube 10 shown in FIG. 3, the slit 14 C portion of the intermediate layer 14 is in close contact with the valley portion 24 of the covering layer 20, and the valley portion 24 in which the convex portion 14 B of the intermediate layer 14 is adjacent. Are engaged between the side walls 24B. Therefore, the intermediate layer 14 can easily move in the same direction following the movement of the covering layer 20 in the axial direction S. Therefore, in the operation of exposing the end of the composite tube 10, the covering layer 20 and the intermediate layer 14 The end of the composite tube 10 can be easily exposed by pushing along the direction S. That is, with respect to the movement of the covering layer 20, it can be effectively suppressed that the intermediate layer 14 is left behind on the outer periphery of the tubular body 12.

  Furthermore, in the composite pipe 10, since the intermediate layer 14 is formed of a sheet-like foam material, the slidability with respect to the pipe body 12 is improved, and when connecting to the pipe joint, as shown in FIGS. In addition, the covering layer 20 can be easily shifted and pressed along the axial direction S.

In the composite pipe 10, the thickness of the intermediate layer 14 is set to be thicker than the difference between the outer circumference of the tubular body 12 in the radial direction R and the inner circumference of the covering layer 20 in the natural state. Similarly, the thinnest thickness at the portion of the slit 14C of the intermediate layer 14 is set to be thicker than the difference between the outer periphery of the tubular body 12 in the radial direction R and the valley portion 24 of the covering layer 20 in the natural state. For this reason, as shown in FIG. 3, the portion of the slit 14C of the intermediate layer 14 is compressed by the valley portion 24 of the covering layer 20 to be a portion to be held. At this portion, the adhesion between the intermediate layer 14 and the covering layer 20 can be improved.
In addition, as shown in FIG. 3, the portion of the convex portion 14B between the slits 14C of the intermediate layer 14 enters the peak space 23 of the peak portion 22 of the covering layer 20, and between the side walls 24B of the adjacent valleys 24. Is engaged. For this reason, when the covering layer 20 is pressed along the axial direction S at the end of the composite tube 10 and shortened and deformed, the movement of the covering layer 20 becomes easy to follow the movement of the covering layer 20. The middle layer 14 can be rigidly shortened to expose the end of the tube 12.

  In the composite pipe 10, the length in the axial direction S of the mid layer 14 shown in FIGS. 1 to 4 in the natural state is set to a range of 90% to 100% of the length in the same direction of the covering layer 20. Be done. At such a ratio, the intermediate layer 14 can be released from the stretched state and held between the tubular body 12 and the covering layer 20. Therefore, relative movement between the covering layer 20 and the intermediate layer 14 is difficult to occur, and the intermediate layer 14 can be shortened and deformed following the shortening deformation of the covering layer 20. Therefore, the end of the tube 12 is reliably exposed. It can be done.

  Further, in the composite pipe 10, the MFR of the covering layer 20 shown in FIGS. 1 to 3 is 0.25 or more, and additionally, the intermediate layer 14 is formed of a foam material. The resin of the covering layer 20 can easily enter. Therefore, the adhesion between the covering layer 20 and the intermediate layer 14 can be improved.

[Modification]
In the composite pipe 10 according to the first embodiment, as shown in FIGS. 1 to 3, in the intermediate layer 14, the slits 14C are disposed on the side of the cover layer 20 of the intermediate layer main body 14A. There is. Although illustration is omitted, in the composite pipe 10 according to the modification, the slit 214C is disposed on the side of the pipe body 12 of the middle layer main body 14A.
According to the composite pipe 10 configured in this manner, the intermediate layer 14 is easily deformed along the axial direction S, so the covering layer 20 and the intermediate layer 14 may be extended along the axial direction S at the end of the tube 12. It can be easily shortened and deformed.

Second Embodiment
A composite pipe 10 according to a second embodiment of the present invention will be described with reference to FIG.

[Composition of compound tube 10]
The composite pipe 10 according to the present embodiment differs in the configuration in which the intermediate layer 14 of the composite pipe 10 according to the first embodiment is replaced with a composite intermediate layer 140. The composite pipe 10 according to the present embodiment and the composite pipe 10 according to the first embodiment have the same configuration except for the difference in the configuration.

(1) Configuration of Composite Intermediate Layer 140 As shown in FIG. 10, the composite intermediate layer 140 of the composite tube 10 comprises the intermediate layer 14 of the composite tube 10 according to the first embodiment, the intermediate layer 14 and the tubular body 12. And a sheet-like low-friction resin layer 14D disposed therebetween. The sliding resistance value of the inner peripheral surface of the low friction resin layer 14D, specifically, the sliding resistance value with the outer peripheral surface of the tubular body 12 is set to a value smaller than the sliding resistance value of the intermediate layer 14 with the tubular body 12 ing.

(2) Configuration of Low Friction Resin Layer 14D The thickness of the low friction resin layer 14D in the natural state is set to be thinner than the thickness of the intermediate layer 14 in the natural state. Here, the thickness of the intermediate layer 14 means the thickness of the slit 14C portion which is the thinnest in the intermediate layer 14 of the composite tube 10 according to the first embodiment described above. In other words, the thickness of the intermediate layer 14 is set to be thicker than the thickness of the low friction resin layer 14D. The middle layer 14 has a role of heat protection in the composite tube 10, and the heat protection can be improved as the thickness of the middle layer 14 increases.
On the other hand, since the thickness of the low friction resin layer 14D is set to be thin, when the covering layer 20 is shortened and deformed along the axial direction S, the followability of the low friction resin layer 14D can be improved. Therefore, in the composite intermediate layer 140, the thickness of the intermediate layer 14 is relatively thick, and the thickness of the low-friction resin layer 14D is relatively thin, so that both the thermal protection property and the followability are improved. It is done.
Further, from the viewpoint of the heat protection property and the followability to the covering layer 20, the thickness in the natural state of the intermediate layer 14 is set in the range of 10 times to 200 times the thickness of the low friction resin layer 14D. Furthermore, the thickness of the intermediate layer 14 is more preferably set in the range of 20 times to 150 times the thickness of the low friction resin layer 14D, and still more preferably set in the range of 25 times to 100 times.

Describing in detail, the thickness of the low-friction resin layer 14D is set in the range of 0.05 mm to 7 mm from the viewpoint of the followability to the coating layer 20. The thickness of the low friction resin layer 14D is preferably set in the range of 0.08 mm to 5 mm, and the thickness of the low friction resin layer 14D is further set in the range of 0.1 mm to 3 mm. More preferred. Here, the thickness of the low friction resin layer 14D is taken as an average value of values obtained by taking out the low friction resin layer 14D from the composite pipe 10 and measuring three arbitrary places.
Further, in the radial direction R, the difference between the outer periphery of the low friction resin layer 14D and the inner side wall 24A of the valley portion 24 of the covering layer 20, ie, the thickness of the slit 14C portion of the intermediate layer 14 in the compressed sandwiching state is, for example, 0. It is set in the range of 3 mm to 5 mm. Furthermore, the thickness is preferably set in the range of 0.5 mm to 3 mm, and more preferably in the range of 1 mm to 2 mm.

  Examples of the resin as the low friction resin layer 14D include polyester, nylon, polyolefin (more specifically, any of polyethylene, polypropylene and polybutene). The low friction resin layer 14D may contain other additives as long as it contains the above-mentioned resin as a main component.

As a form of low friction resin layer 14D, a nonwoven fabric, a knit, textiles, a film, etc. are mentioned, for example. The non-woven fabric includes, for example, melt blow, spun bond and the like. Knitting includes, for example, Russell, Tricot, Milanese and the like. The woven fabric includes, for example, plain weave, twill weave, imitation twill weave, twill weave, entanglement and the like.
In particular, as the low friction resin layer 14D, a polyester non-woven fabric containing polyester as a main component, a polyester tricot, a nylon non-woven fabric containing nylon as a main component, a nylon tricot, and a polyethylene film containing polyethylene as a main component are preferable. Furthermore, polyester non-woven fabric or nylon tricot is more preferable for the low friction resin layer 14D.
Also, if the nonwoven fabric is employed in the low-friction resin layer 14D, the basis weight of the nonwoven fabric is set in a range of, for example ^{10g / m 2 ~500g / m 2} . Also, the basis weight of the nonwoven fabric is is preferably set in a range of ^{12g / m 2 ~200g / m 2} , further basis weight of the nonwoven fabric more be set in the range of ^15g / ^{m 2 ~25g} / m 2 preferable.

The sliding resistance value (unit: "N") on the inner peripheral surface of the low friction resin layer 14D is not particularly limited as long as it is smaller than the sliding resistance value on the inner peripheral surface of the intermediate layer 14, for example, 10N to 24N It is set. Preferably, the slip resistance value is set in the range of 12N to 23N.
The sliding resistance value on the inner peripheral surface of the low friction resin layer 14D is set to 0.36 times to 0.90 times the sliding resistance value on the inner peripheral surface of the intermediate layer 14, preferably 0.44 times. It is set in the range of ~ 0.85 times.

  The inner circumferential surface of the low friction resin layer 14D covers the outer periphery of the tube 12 while being in full contact with the outer periphery of the tube 12. Here, "entirely contact" means that all parts do not have to be in intimate contact and substantially all surfaces are in contact. Therefore, in the concept of “entirely contact”, the low friction resin layer 14 D and the intermediate layer 14 or the tube 12 may be partially peeled off at the joint of the composite intermediate layer 140 wound around the tube 12. included. In addition, also in the case where the low friction resin layer 14D and the intermediate layer 14 or the tube 12 are partially peeled off due to the complex intermediate layer 140 being wrinkled between the tube 12 and the covering layer 20, It is included in the concept of “contact”.

As a method of bonding the middle layer 14 and the low friction resin layer 14D in the composite middle layer 140, a method of bonding by the frame laminating method can be mentioned other than a method of applying and bonding an adhesive between both layers. . In particular, the latter frame laminating method is preferred. That is, the composite intermediate layer 140 is configured as a frame-laminated adhesive (hereinafter, also simply referred to as a "flare adhesive").
Specifically, in the flame laminating method, for example, a soluble substance contained in the intermediate layer (porous resin layer) 14 is thermally melted by flame and exuded, and a low friction resin is used by using the exuded melt. It is a method of adhering to the layer 14D. The composite intermediate layer 140 formed of the flash adhesive can be made thinner as compared to the case where the adhesive is applied and formed. For this reason, in the case of the composite pipe 10 including the peel adhesive as the composite intermediate layer 140, the followability to the covering layer 20 can be improved when the end of the tubular body 12 is exposed. It is possible to make burrs less likely to occur in the covering layer 20 in the manufacturing process.

Here, the above-mentioned "slip resistance value" was measured as follows, for example. In the case of measuring the sliding resistance value on the inner peripheral surface of the low friction resin layer 14D, first, the coating layer 20 is disposed on the outer peripheral side of the tubular body 12, and the composite intermediate layer 140 is inserted between the tubular body 12 and the coating layer 20. It was done. The low friction resin layer 14 D of the composite intermediate layer 140 was inserted in contact with the tube 12. The composite tube 10 was manufactured to have a length of 200 mm in the axial direction S. Then, one end of the composite pipe 10 is connected to the tip of a force gauge (IMADA popular digital force gauge DS2), and the coating layer 20 is 50 mm along the axial direction S at the other end of the composite pipe 10 The offset force (unit: N) was measured.
Further, in the case of measuring the sliding resistance value on the inner peripheral surface of the intermediate layer 14 of the composite pipe 100 according to the comparative example, first, the covering layer 20 is disposed on the outer peripheral side of the pipe 12. The intermediate layer 14 was inserted therebetween. The intermediate layer 14 was inserted in contact with the tube 12. The composite pipe 100 was manufactured to have a length of 200 mm in the axial direction S. Then, in the same manner as the measurement of the sliding resistance value of the low friction resin layer 14D, the sliding resistance value of the intermediate layer 14 was measured.

  DESCRIPTION OF SYMBOLS 10 ... Composite pipe | tube 12 Tube body 14 Intermediate layer 14A Intermediate layer main body 14B Convex part 14C Slit 14D Low friction resin layer 140 Composite intermediate layer 20 Coating layer 22 Mountain part, 22A ... outer wall, 23 ... mountain space, 24 ... valley part, 24A ... inner wall, 30 ... manufacturing apparatus.

Claims (5)

Tube body,
An annular ridge which is tubular and covers the outer periphery of the tube and which is convex radially outward, and an annular valley which is concave radially outward are alternately arranged along the axial direction of the tube. A cover layer which is arranged in an accordion shape and which is guided along the outer circumference of the tube and can be shortened along the axial direction;
It is disposed between the tubular body and the covering layer, and is formed in a sheet shape in which the axial direction is a longitudinal direction and a direction intersecting the axial direction is a lateral direction, and the lateral direction is a slit length An intermediate layer having a plurality of slits disposed in a direction and at regular intervals in the slit width direction,
Composite tube with.   The composite pipe according to claim 1, wherein the slit is disposed on the covering layer side of the intermediate layer.   The said slit is arrange | positioned by the said coating layer side of the said intermediate | middle layer, and it is formed in the cross-sectional shape from which radial direction outer side becomes concave in agreement with the arrangement interval in the said axial direction of the said valley part. The composite pipe according to Item 2.   The slit length direction of the slit is matched with the direction which makes an angle of 45 degrees or more and 135 degrees or less in absolute value with respect to the axial direction according to any one of claims 1 to 3. Composite tube.   The composite tube according to any one of claims 1 to 4, wherein the slit is disposed on the tube side of the intermediate layer.