JP7499111B2 - Pipe assembly and multi-layer pipe - Google Patents

Description

The present invention relates to a pipe assembly having multiple pipes with an internal space through which fluids, etc. can pass, and a multi-layer pipe having an internal space through which fluids, etc. can pass.

Conventionally, multiple tubes having an internal space through which fluids can pass are grouped together to form a tube assembly, which is then arranged inside an enclosure member. When arranging the tube assembly in this way, it is necessary to bend or curve the tube assembly according to the shape of the installation location, etc.

JP 2004-340223 A

When installing the pipe assembly described in Patent Document 1, it is necessary to bend or curve the pipe assembly according to the shape of the installation location. In this case, the pipes that make up the pipe assembly slide against each other at the bent or curved locations of the pipe assembly, and the sliding resistance at that time may increase the stress required for bending or curving.

The present invention was made to solve the above problems, and its main objective is to provide a pipe assembly that can reduce the stress required when bending or curving, and a multi-layer pipe that constitutes the pipe assembly.

The first configuration is a tube assembly in which multiple tubes are bundled together with their sides surrounded by an enclosing member, and at least two of the multiple tubes are provided with friction reduction means for reducing the relative axial sliding resistance of the two tubes.

The first configuration is equipped with a friction reduction means, which reduces the stress required when bending.

The second configuration is the same as the first configuration, but the multiple tubes are surrounded by an enclosing member so that they are not spaced apart from each other.

The third configuration is the same as the first or second configuration, except that the surrounding member is long and tubular, and the multiple tubes are disposed within the surrounding member.

The second and third configurations also make it possible to prevent the tubes from separating when bending the tubes.

The fourth configuration is any one of the first to third configurations, in which the outer surfaces of the two tubes are capable of contacting each other, and the friction reduction means is provided on at least one of the two tubes.

In the fourth configuration, since the friction reduction means is provided in the tube, there is no need to provide a separate friction reduction means, and the overall configuration can be simplified.

The fifth configuration is any one of the first to fourth configurations, in which friction reduction means is provided on all of the multiple pipes.

When constructing a pipe assembly from three or more pipes, if some of the pipes are not provided with friction reduction means, it is necessary to consider the arrangement so that the pipes that are not provided with friction reduction means do not come into contact with each other, or to bend the pipes so that they do not slide against each other. In this regard, with the fifth configuration, there is no need to consider the arrangement, especially when constructing a pipe assembly from three or more pipes, and this simplifies the manufacturing process of the pipe assembly.

The sixth configuration is any one of the first to fourth configurations, in which the outer surfaces of the two tubes are capable of contacting each other, and the friction reduction means is provided on only one of the two tubes.

In the sixth configuration, it is possible to use a known tube that does not have a friction reduction means for one of the tubes.

The seventh configuration is the same as the sixth configuration, in which the friction reduction means is a rough outer surface that is rougher than the outer surface of a pipe that does not have the friction reduction means.

In the seventh configuration, it is possible to configure a friction reduction means by the structure of the outer surface of the tube.

The eighth configuration is any one of the fourth to seventh configurations, in which the friction reduction means is a rough outer surface that is rougher than the inner surface of the tube.

In the eighth configuration, the rough outer surface can reduce friction between the tubes while suppressing resistance to objects passing through the inside of the tube.

The ninth configuration is any one of the fourth to eighth configurations, in which the pipe provided with the friction reduction means is a multi-layer pipe having an inner layer forming the inner surface of the pipe and an outer layer forming the outer surface of the pipe, and the material of the outer layer is capable of forming a surface that can reduce sliding resistance more than the material of the inner layer.

In the ninth configuration, the material of the innermost layer can be a material suitable for reducing resistance to objects passing through the inside of the tube, and the material of the outermost layer can be a material suitable for forming a friction reduction means.

The tenth configuration is the same as the ninth configuration, except that the multi-layer pipe is a two-layer pipe in which an inner layer and an outer layer are stacked in the radial direction.

In the tenth configuration, as in the ninth configuration, a material suitable for reducing resistance to fluids passing through the inside of the tube can be used as the material for the innermost layer, and a material suitable for forming a friction reduction means can be used as the material for the outermost layer. In addition, since the tube is made up of two layers, an inner layer and an outer layer, manufacturing costs can be reduced.

The eleventh configuration is the same as any of the fourth to tenth configurations, except that the friction reduction means is provided continuously in the axial direction.

In the 11th configuration, the effect of reducing sliding resistance can be obtained regardless of where the tube is curved.

The twelfth configuration is any one of the first to twelfth configurations, and furthermore, the inner surfaces of the two tubes are made of the same material.

If the inner surfaces of the tubes are made of different materials, it may be necessary to select the tube through which an object is to be passed when passing it through the tubes. In the 12th configuration, the inner surfaces of the tubes are made of the same material, so the object passes through the inside of either tube with the same results, reducing the effort required to pass an object through the tubes.

The thirteenth configuration is any one of the first to third configurations, in which the friction reduction means is an interposed body interposed between the two pipes.

In the thirteenth configuration, even when using known pipes that have high sliding resistance when adjacent to each other, the intervening body can reduce sliding resistance.

The fourteenth configuration is the same as the thirteenth configuration, except that the intermediate body is arranged continuously in the axial direction of the two tubes.

In the 14th configuration, similar to the 11th configuration, the effect of reducing sliding resistance can be obtained regardless of where the tube is curved.

The fifteenth configuration is the same as the thirteenth or fourteenth configuration, in which the interposer is strip-shaped and extends in the axial direction of the two pipes, and the sliding resistance at the contact point of the interposer with at least one of the two pipes is lower than the sliding resistance when the two pipes are in contact.

In the fifteenth configuration, as in the thirteenth configuration, even when using known pipes that have high sliding resistance when adjacent to each other, the intervening body can reduce sliding resistance.

The sixteenth configuration is the same as the thirteenth or fourteenth configuration, in that the intervening body is a band extending in the axial direction of the two pipes, and multiple sheets are overlapped in the direction in which the two pipes are adjacent, and the sliding resistance between the intervening bodies is lower than the sliding resistance between the intervening body and the two pipes.

The 16th configuration can effectively tolerate changes in the relative positions of the two tubes while suppressing deviations in the relative positions of the tube and the intervening body.

The seventeenth configuration is any one of the thirteenth to fifteenth configurations, and in addition, at least one of the contact points between the inclusion and the tube, the inclusion has a rough outer surface whose surface roughness is greater than the surface roughness of the tube.

In the seventeenth configuration, the sliding resistance can be reduced simply by forming a rough outer surface on the intermediate body, thereby reducing the manufacturing costs of the tube assembly.

The 18th configuration is any one of the 7th, 8th, and 17th configurations, in addition, the rough outer surface has a surface roughness that is at least 10 times the surface roughness of the comparison surface.

In the 18th configuration, the effect of a rough outer surface can be obtained while maintaining the functionality achieved by smoothing the smooth surface, which is the comparison surface.

The nineteenth configuration is the same as the first to third configurations, except that the friction reducing means is applied or attached to the outer surface of at least one of the two tubes.

In the 19th configuration, even when using known pipes that have high sliding resistance when adjacent to each other, the friction reduction means makes it possible to reduce sliding resistance.

The 20th configuration is a multi-layer pipe in which different synthetic resin materials are laminated in the radial direction, with an inner layer forming the inner surface of the pipe and an outer layer forming the outer surface of the pipe, and the surface roughness of the outer surface is at least 10 times rougher than the surface roughness of the inner surface.

In the 20th configuration, a material can be used that is suitable for suppressing the sliding resistance when multi-layer pipes contact each other or when a multi-layer pipe contacts a single-layer pipe and slides against each other, while suppressing the resistance to fluids, etc., passing through the inside of the multi-layer pipe.

FIG. 2 is a diagram showing the external appearance of the tube assembly according to the first embodiment. FIG. 2 is a cross-sectional view of a tube in the tube assembly according to the first embodiment. FIG. 2 is a diagram showing a rough outer surface of the tube assembly according to the first embodiment. FIG. 11 is a cross-sectional view of a tube assembly according to a second embodiment. FIG. 11 is a cross-sectional view of a tube assembly according to a third embodiment. FIG. 10 is a cross-sectional view of a tube assembly according to a fourth embodiment. FIG. 11 is a cross-sectional view of a tube assembly according to another embodiment A. FIG. 11 is a cross-sectional view of a tube assembly according to another embodiment B. FIG. 11 is a cross-sectional view of a tube assembly according to another embodiment C. FIG. 13 is a cross-sectional view of a tube assembly according to another embodiment D. FIG. 13 is a cross-sectional view of a tube assembly according to another embodiment E. FIG. 11 is a cross-sectional view of a tube assembly according to another embodiment F. FIG. 11 is a cross-sectional view of a tube assembly according to another embodiment G. FIG. 13 is a cross-sectional view of a tube assembly according to another embodiment H. FIG. 13 is a cross-sectional view of a tube assembly according to another embodiment I.

First Embodiment
A tube assembly 10 according to this embodiment will be described with reference to Figs. 1 to 3. The tube assembly 10 according to this embodiment is composed of two long cylindrical tubes 20 and an enclosing member 30 that encloses and bundles the tubes 20. The enclosing member 30 is a thin aluminum tape that is wound around the outer periphery of the two tubes 20. The enclosing member 30 suppresses the separation between the tubes 20 (separation of the axial centers). The enclosing member 30 and the tubes 20 are not bonded, and the tube 20 is slidable in the enclosing member 30 relative to the other tube 20 and the enclosing member 30 in the axial direction.

The tube 20 has a two-layer structure consisting of an inner layer 21 that forms the inner surface and an outer layer 22 that forms the outer surface. The inner layer 21 has a substantially uniform thickness in the radial direction around the entire circumference, and is made of non-crosslinked polyethylene resin (PE-RT). The outer layer 22 also has a substantially uniform thickness in the radial direction around the entire circumference, and is made of high-density polyethylene resin (HDPE). The inner layer 21 is 1.5 mm thick, and the outer layer 22 is 50 μm thick. This tube 20 is formed by co-extrusion molding, in which non-crosslinked polyethylene resin and high-density polyethylene resin are co-extruded into a cylindrical shape.

The outer surface of the tube 20 is formed with fine irregularities all over, which form the rough outer surface 23. The irregularities of the rough outer surface 23 are formed by the properties of the material during the process of extrusion and hardening in co-extrusion molding.

The rough outer surface 23 will be described with reference to FIG. 3. The rough outer surface 23 is formed by continuous irregularities, and has various known irregular shapes such as a cone shape or a pyramid shape. In this embodiment, the average value of the height D from the apex of the convex part to the bottom of the concave part of the irregularities is defined as the surface roughness. The surface roughness in this embodiment is 1.5 μm.

On the other hand, a smooth surface is formed on the inner surface of the tube 20, which is smoother than the rough outer surface 23. Although slight irregularities exist on this smooth surface, the surface roughness of the irregularities is 0.03 to 0.05 μm. The irregularities on the smooth surface are formed by the properties of the material during the process of extrusion and hardening in co-extrusion molding. In other words, the surface roughness of the rough outer surface 23 is about 30 to 50 times that of the smooth surface.

When the tubes 20 described above are bundled together by the enclosing member 30 to form the tube assembly 10, when bending the tube assembly 10, the greater the sliding resistance between the outer surfaces, the greater the stress required for bending, and the smaller the sliding resistance between the outer surfaces, the less stress required for bending. Because the tubes 20 have the rough outer surface 23 on their outer surfaces, the contact area between the tubes 20 is smaller than when they do not have the rough outer surface 23, and therefore the sliding resistance is smaller. This reduces the stress required when bending the tube assembly 10.

When bending the tube assembly 10 in the vertical direction in FIG. 1, the tubes 20 slide against each other only to a limited extent. On the other hand, when bending the tube assembly 10 in the horizontal direction in FIG. 1, the tubes 20 slide against each other, and the greater the sliding resistance, the greater the stress required. In this regard, the rough outer surface 23 of the outer surface suppresses the sliding resistance, and the necessary stress can be suitably reduced. Since the rough outer surface 23 can suppress the sliding resistance, the rough outer surface 23 and/or the outer layer 22 forming the rough outer surface 23 can be referred to as a friction reduction means. Also, since the friction reduction means is provided on the tube 20, it can be said that the relative positions of the tube 20 and the friction reduction means do not change.

The numerical values of the surface roughness of the rough outer surface 23 and the surface roughness of the smooth surface described above are merely examples, and various modifications are possible. If the surface roughness of the rough outer surface 23 is greater than that of the smooth surface, a certain effect can be obtained, but if the effect of smoothing the smooth surface is to be obtained at the same time, it is preferable that the rough outer surface 23 has a surface roughness of 10 times or more than that of the smooth surface. In other words, if the surface roughness of the smooth surface is about 0.05 μm, it is preferable that the surface roughness of the rough outer surface 23 is 10 times or more, that is, 0.5 μm or more. On the other hand, if the surface roughness is several tens of μm, the unevenness may mesh with the other tube 20, increasing the sliding resistance. In addition, various modifications are possible for the thickness of the inner layer 21 and the outer layer 22.

In addition to suppressing sliding resistance, the pipe assembly 10 and multi-layer pipe 20 according to this embodiment also provide the following advantages:

- The surrounding member 30 makes it possible to bend the tubes 20 while preventing them from separating from each other.

- The rough outer surface 23 serving as a friction reduction means is provided on the tube 20 itself, so there is no need to provide a separate friction reduction means, and the overall structure can be simplified.

- The inner surface of the tube 20 is smooth, which reduces resistance when a fluid passes through the inside of the tube 20, while the rough outer surface 23 reduces friction between the tubes 20.

- A material suitable for suppressing resistance to objects such as fluids passing through the inside of the tube 20 can be used as the material for the inner layer 21, and a material suitable for forming the rough outer surface 23 can be used as the material for the outer layer 22. In addition, because it is a two-layer tube, the manufacturing costs can be reduced compared to a tube having three or more layers.

- Because the two tubes 20 are identical, the object passing through either tube 20 is equivalent, which reduces the effort required to distinguish between tubes 20 when passing an object through them.

- The surface roughness of the rough outer surface 23 is about 30 times that of the smooth surface, so the effect of the rough outer surface 23 can be obtained while maintaining the smoothing function of the smooth surface.

Second Embodiment
In this embodiment, the configuration of the tube assembly 100 is different from that of the first embodiment. The tube assembly 100 according to this embodiment will be described with reference to FIG.

The pipe assembly 100 includes two pipes 20, 40, which are bundled together by an enclosing member 30, as in the first embodiment. Of the two pipes 20, 40, one of the pipes 20 has a two-layer structure similar to the pipe 20 shown in the first embodiment, and is therefore referred to as a multi-layer pipe 20, and a detailed description thereof will be omitted.

The other pipe 40 is called a single-layer pipe 40 because it is a pipe made entirely of one type of material. The material of the single-layer pipe 40 is the same non-crosslinked polyethylene resin (PE-RT) as the inner layer 21 of the multi-layer pipe 20, and it is formed by extrusion molding. The inner and outer surfaces of this single-layer pipe 40 are smooth, just like the inner surface of the single-layer pipe 20, due to the properties of the material during the extrusion molding process.

When the multi-layer pipe 20 and the single-layer pipe 40 configured as described above come into contact and slide, the contact area is smaller than when the single-layer pipes 40 come into contact with each other, and the sliding resistance is also smaller. Therefore, as in the first embodiment, even if the pipes 20, 40 slide when bending the pipe assembly 100, it can be bent with less stress.

In addition, in this embodiment, the outer surface of the single-layer pipe 40 does not need to be roughened, so it is possible to use a known pipe for the single-layer pipe 40.

The surface roughness of the rough outer surface 23 of the multi-layer pipe 20 in this embodiment is similar to that of the first embodiment, but since it does not mesh with the smooth outer surface of the single-layer pipe 40, the upper limit of the surface roughness can be made larger.

With the above configuration, the tube assembly 100 according to this embodiment has the following advantages in addition to those of the tube assembly 10 according to the first embodiment.

- Although the multi-layer pipe 20 and the single-layer pipe 40 have different outer structures, the inner structures are the same, so no matter which pipe 20 an object passes through, it is the same. As with the first embodiment, this reduces the effort required to distinguish between pipes 20 when passing an object through them.

Third Embodiment
The tube assembly 200 according to this embodiment will be described with reference to Fig. 5. The tube assembly 200 according to this embodiment is configured to include two single-layer tubes 40 as shown in the second embodiment, and the two single-layer tubes 40 are bundled together by an enclosing member 30. A long plate-like interposer 50 extending in the extension direction of the tubes 40 is disposed between the single-layer tubes 40 so as to be slidable with the single-layer tubes 40.

The material of this inclusion 50 is, for example, high-density polyethylene resin (HDPE), the same as the material of the outer layer 22 of the multi-layer pipe 20 in the first embodiment, and a rough outer surface with a surface roughness of about 1.5 μm is formed on both sides. This rough outer surface is formed due to the characteristics of the material in the process of pouring high-density polyethylene resin into a mold and hardening it, similar to the rough outer surface 23 of the multi-layer pipe 20 in the first embodiment. The numerical range of the surface roughness of the rough outer surface of this inclusion 50 may be similar to that of the first embodiment.

When bending the pipe assembly configured as described above, the single-layer pipes 40 abut against the rough outer surface of the intermediate body 50, so sliding resistance is reduced, similar to the case in the second embodiment where the single-layer pipes 40 abut against the rough outer surface 23 of the multi-layer pipe 20. This reduction in sliding resistance means that resistance during relative axial movement of the two single-layer pipes 40 is reduced. Therefore, the stress required to bend the pipe assembly 200 can be reduced, similar to the first and second embodiments.

With the above configuration, the tube assembly 200 according to this embodiment has the following advantages in addition to some of the advantages of the first and second embodiments.

- Even when using known single-layer pipes 40 that have high sliding resistance when adjacent to each other, the interposer 50 can reduce sliding resistance.

- By simply forming a rough outer surface on the intermediate body 50, sliding resistance can be reduced, thereby reducing the manufacturing costs of the tube assembly 200.

Fourth Embodiment
The pipe assembly 300 according to this embodiment will be described with reference to Fig. 6. The pipe assembly 300 according to this embodiment has two long plate-like intermediate bodies 60 arranged in the extension direction of the single-layer pipes 40, and the structure of the intermediate bodies 60 is different from that of the third embodiment.

The inclusion body 60 has a two-layer structure in which layers made of two different materials are laminated, with the first layer 61 being made of non-crosslinked polyethylene resin (PE-RT) and the second layer 62 being made of high-density polyethylene resin (HDPE). The surface of the first layer 61 is a smooth surface with a surface roughness of about 0.03 to 0.05 μm, and the surface of the second layer 62 is a rough outer surface with a surface roughness of about 1.5 μm. The first layer 61 side of the inclusion body 60 abuts against the single-layer pipe 40, and the second layers 62 abut against each other facing each other. In other words, the smooth surface of the inclusion body 60 abuts against the smooth outer surface of the single-layer pipe 40, and the rough outer surfaces of the inclusion bodies 60 abut against each other.

As a result of the above configuration, when the tube assembly 300 is bent, the shift in the relative position between the single-layer tubes 40 and the intermediate body 60 is suppressed by the sliding resistance. On the other hand, since the sliding resistance between the intermediate bodies 60 is reduced, the stress required when changing the relative position of the two single-layer tubes 40 can be reduced. In addition, effects equivalent to those of the first and second embodiments can be achieved.

<Other embodiments>
A pipe assembly 10a according to another embodiment A will be described with reference to Fig. 7. The pipe assembly 10a according to another embodiment A is composed of three multi-layer pipes 20, which are arranged so that the central axes of the multi-layer pipes 20 form the vertices of an equilateral triangle. The sliding resistance between the multi-layer pipes 20 is suppressed in the same manner as in the first embodiment, so that the stress required for bending can be reduced.

- A pipe assembly 10b according to another embodiment B will be described with reference to FIG. 8. The pipe assembly 10c according to another embodiment B is composed of one multi-layer pipe 20 and two single-layer pipes 40, and is arranged so that the central axes of the three pipes 20, 40 form the vertices of an equilateral triangle. The sliding resistance between the multi-layer pipe 20 and the single-layer pipe 40 is suppressed in the same way as in the second embodiment. Therefore, the stress required for bending can be reduced, particularly when bending in a direction in which the single-layer pipes 40 do not slide against each other.

- A pipe assembly 10c according to another embodiment C will be described with reference to FIG. 9. The pipe assembly 10c according to another embodiment C is composed of two multi-layer pipes 20 and one single-layer pipe 40, and is arranged so that the central axes of the three pipes 20, 40 form the vertices of an equilateral triangle. The sliding resistance between the multi-layer pipes 20 and the single-layer pipe 40 is suppressed in the same way as in the second embodiment. Therefore, the stress required for curving can be reduced regardless of the direction of bending.

- A pipe assembly 10d according to another embodiment D is described with reference to FIG. 10. The pipe assembly 10d according to another embodiment D is composed of two multi-layer pipes 20 and one single-layer pipe 40, and the three pipes are arranged in parallel so that the multi-layer pipes 20 are located on both sides of the single single-layer pipe 40. The sliding resistance between the multi-layer pipes 20 and the single-layer pipes 40 is suppressed as in the second embodiment, so the stress required for bending can be reduced.

- A pipe assembly 10e according to another embodiment E will be described with reference to FIG. 11. The pipe assembly 10e according to another embodiment E is composed of one multi-layer pipe 20 and two single-layer pipes 40, with three pipes arranged in parallel, with the single-layer pipes 40 located on both sides of the one multi-layer pipe 20. As the single-layer pipes 40 on both sides are in contact only with the multi-layer pipes 20, the sliding resistance is suppressed in the same way as in the second embodiment. Therefore, the stress required for bending can be reduced.

- A pipe assembly 10f according to another embodiment F will be described with reference to FIG. 12. The pipe assembly 10f according to another embodiment F is composed of four multi-layer pipes 20, which are arranged so that the central axes of the four multi-layer pipes 20 form the vertices of a square. The sliding resistance between these multi-layer pipes 20 is suppressed in the same way as in the first embodiment, so the stress required for bending can be reduced.

- A pipe assembly 10g according to another embodiment G will be described with reference to FIG. 13. The pipe assembly 10g according to another embodiment G is composed of two multi-layer pipes 20 and two single-layer pipes 40, and is arranged so that the multi-layer pipes 20 are adjacent to each other and the single-layer pipes 40 are adjacent to each other, and the central axes of the four pipes 20, 40 form the vertices of a square. The sliding resistance between the multi-layer pipes 20 and the single-layer pipes 40 is suppressed as in the second embodiment. Therefore, the stress required for bending can be reduced, particularly when bending in a direction in which the single-layer pipes 40 do not slide against each other.

- A pipe assembly 10h according to another embodiment H will be described with reference to FIG. 14. The pipe assembly 10h according to another embodiment H is composed of two multi-layer pipes 20 and two single-layer pipes 40, and is arranged such that one multi-layer pipe 20 is adjacent to two single-layer pipes 40, and one single-layer pipe 40 is adjacent to two multi-layer pipes 20, and the central axes of the four pipes 20, 40 form the vertices of a square. The sliding resistance between the multi-layer pipes 20 and the single-layer pipes 40 is suppressed in the same way as in the second embodiment. Therefore, the stress required for bending can be reduced regardless of the direction of bending.

- A pipe assembly 10i according to another embodiment I will be described with reference to FIG. 15. The pipe assembly 10i according to another embodiment I is composed of three multi-layer pipes 20 and one single-layer pipe 40, and is arranged so that the central axes of the four pipes 20, 40 form the vertices of a square. The sliding resistance between the multi-layer pipe 20 and the single-layer pipe 40 is suppressed in the same manner as in the second embodiment. Therefore, the stress required for curving can be reduced regardless of the direction of bending.

<Modification>
In the multi-layer pipe 20 in the first and second embodiments, the rough outer surface may not be provided over the entire outer surface, but may be provided in a band shape only at the portion that abuts the other pipe 20, 40. Also, it may not be provided over the entire longitudinal direction, but may be provided only on a portion of the longitudinal direction. In the pipe assembly 10, 100, it is not necessarily required to bend over the entire longitudinal direction, and as long as a rough outer surface is formed at least at the portion that needs to be bent, the stress required when bending can be reduced.

- In the embodiment, the outer layer 22 of the multi-layer pipe 20 is formed with a rough outer surface 23, and the inner layer 21 is formed with a smooth surface, but as long as at least the outer layer 22 is formed with a rough outer surface that functions as a friction reduction means, a certain degree of effect can be achieved. Also, although a two-layer structure consisting of the inner layer 21 and the outer layer 22 is used, a multi-layer structure consisting of three or more layers may also be used.

- In the embodiment, a rough outer surface consisting of fine irregularities is formed due to the characteristics of the hardened polyethylene resin when it is hardened, but the rough outer surface may also be formed by providing fine irregularities on the mold and transferring the irregularities to the resin.

- In the embodiment, the average height of the projections and recesses is used to measure the surface roughness, but the spacing between the projections may also be defined as the surface roughness. Even in this case, the rougher the surface roughness, the wider the spacing between the projections, and the smaller the contact area.

- In the embodiment, the rough outer surface has fine continuous irregularities, but it may have linear protrusions or linear grooves extending in the axial or circumferential direction. In this case, they may be straight or curved. If the rough outer surface of one tube extends in the axial direction and the rough outer surface of the other tube extends in the circumferential direction, they will not interlock with each other, and the upper limit of surface roughness can be made larger.

The materials shown in the embodiment are only examples, and various modifications are possible. Instead of the hard polyethylene resin, another material capable of forming a rough outer surface due to the characteristics of the material when hardened may be selected, and instead of the non-crosslinked polyethylene resin, another material capable of forming a smooth surface due to the characteristics of the material when hardened may be selected. Furthermore, if a method of forming a rough outer surface by transferring fine irregularities provided in a mold is adopted, a material other than a material capable of forming a rough outer surface due to the characteristics when hardened can be adopted, and in a single-layer pipe, the inner surface can be made smooth and the outer surface can be made rough. Furthermore, the outer surface can be formed by roughening the surface of the outer layer of the pipe or the intermediate body with a file or the like. Even in this case, in a single-layer pipe, the inner surface can be made smooth and the outer surface can be made rough.

- In the embodiment, the surrounding member 30 is a thin film tape made of aluminum, but it may be made of other materials such as resin. Also, a long tube may be used as the surrounding member, and a single-layer tube 40 or a multi-layer tube 20 may be placed inside it. In this case, the inner tubes 20, 40 may be made separable. When the tube assembly is curved, the tubes 20, 40 may come into contact with each other and slide against each other inside, so even if they are separable, a certain effect can be obtained. Furthermore, when a single-layer tube 40 is placed inside a tube serving as a surrounding member, the inner surface of the surrounding member tube may be made a rough outer surface to suppress sliding resistance.

- When using a single-layer pipe 40 that does not have a rough outer surface, a rough outer surface may be formed on the inner surface of the enclosing member 30 to reduce the sliding resistance between the enclosing member 30 and the single-layer pipe 40.

- In the third embodiment, the rough outer surface is formed on both sides of the intermediate body 50, but it may be formed on only one side. In this case, although the sliding resistance with the tube 40 on the side where the rough outer surface is not formed is greater than on the side where the rough outer surface is formed, the sliding resistance on the side where the rough outer surface is formed is relatively small, and the tube 40 slides on the side where the rough outer surface is formed, so that the tube assembly 200 can be bent with small stress.

- In the third embodiment, the intervening body 50 does not have to be provided over the entire extension direction of the tube 40. Since the intervening body 50 also functions as a spacer for the tube 40, the tube 40 does not come into contact with the portions where the intervening body 50 is not provided, and no sliding resistance occurs, so the tube assembly 200 can be bent with less stress. The same applies to the fourth embodiment.

- In other embodiments, an example in which the pipe assembly is made up of three or four pipes 20, 40 has been shown, but the pipe assembly may be made up of five or more pipes 20, 40. Even in this case, as long as at least one multi-layer pipe 20 is provided, the sliding resistance between the multi-layer pipe 20 and the single-layer pipe 40 can be reduced. In this case, the arrangement of the pipes 20, 40 can be changed in various ways depending on the location where the pipe assembly is used.

- In another embodiment, an example is shown in which the four tubes 20, 40 are arranged so that the central axis forms the vertices of a square, but various arrangements can be adopted, such as arranging the four tubes 20, 40 in parallel.

- In the examples shown in the other embodiments, single-layer pipes 40 may be placed instead of multi-layer pipes 20, and the intervening bodies 50, 60 shown in the third or fourth embodiment may be provided between the single-layer pipes 40. Also, when the multi-layer pipes 20 and single-layer pipes 40 are mixed and the single-layer pipes 40 are arranged so that they abut, the intervening bodies 50, 60 may be placed.

- By winding a member similar to the inclusions 50, 60 according to the third and fourth embodiments in a spiral shape around the outer circumferential surface of the single-layer pipe 40 in the axial direction, it can be treated as a pipe capable of suppressing sliding resistance in the same way as the multi-layer pipe 20. In this case, the surface that contacts the wrapped single-layer pipe 40 may also be a rough outer surface, but if it is a smooth surface, it is possible to suppress the change in the relative position between the inclusion-like member and the single-layer pipe 40 around which it is wrapped, while suppressing sliding resistance with another single-layer pipe.

- As a friction reduction method to suppress the sliding resistance between the tubes, it is also possible to use methods such as applying a liquid or adhering a powder.

Pipe assembly...10, 100, 200, 300, 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, multi-layer pipe...20, inner layer...21, outer layer...22, rough outer surface...23, enclosing member...30, single-layer pipe...40, inclusion...50, 60

Claims (13)

A tube assembly in which a plurality of tubes are bundled together with their sides surrounded by an enclosing member,
A tube assembly, wherein two of the plurality of tubes are capable of contacting each other at their outer surfaces , and at least one of the two tubes is provided with a friction reduction means for reducing the relative axial sliding resistance of the two tubes. A tube assembly in which a plurality of tubes are bundled together with their sides surrounded by an enclosing member,
A tube assembly, wherein all of the plurality of tubes are provided with friction reducing means for reducing relative axial sliding resistance between the tubes . A tube assembly in which a plurality of tubes are bundled together with their sides surrounded by an enclosing member,
A tube assembly, wherein two of the plurality of tubes are capable of contacting each other at their outer surfaces , and a friction reduction means for reducing the relative axial sliding resistance of the two tubes is provided on only one of the two tubes . 4. The tube assembly of claim 3 , wherein the friction reducing means is a rough outer surface having a surface roughness greater than that of an outer surface of a tube not provided with the friction reducing means. The tube assembly according to any one of claims 1 to 4 , wherein the friction reducing means is a rough outer surface having a surface roughness greater than that of the inner tube surface. The pipe provided with the friction reducing means is a multi-layer pipe having an inner layer forming an inner surface of the pipe and an outer layer forming an outer surface of the pipe,
6. The tube assembly according to claim 1, wherein the material of the outer layer is capable of forming a surface that can reduce sliding resistance more than the material of the inner layer. The pipe assembly according to claim 6 , wherein the multi-layer pipe is a two-layer pipe in which the inner layer and the outer layer are laminated in a radial direction. The tube assembly according to any one of claims 1 to 7 , wherein the friction reducing means is provided continuously in the axial direction. A tube assembly in which a plurality of tubes are bundled together with their sides surrounded by an enclosing member,
A tube assembly comprising an interposer interposed between at least two of the plurality of tubes to reduce the relative axial sliding resistance of the two tubes , the interposer being band-shaped and extending in the axial direction of the two tubes . The tube assembly according to claim 9 , wherein a sliding resistance at a contact portion between the intermediate body and at least one of the two tubes is lower than a sliding resistance when the two tubes are in contact with each other. The intermediate body is a plurality of overlapping sheets in the adjacent direction of the two pipes,
The tube assembly according to claim 9 , wherein a sliding resistance between the interposers is lower than a sliding resistance between the interposer and the two tubes. At least one of the contact points between the intermediate body and the pipe,
11. The tube assembly of claim 9 or 10 , wherein the inclusions have a rough outer surface that is rougher than the surface roughness of the tubes. 13. The tube assembly of claim 4, 5 or 12, wherein the rough outer surface has a surface roughness that is at least 10 times that of a comparison surface.

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