Cable protection pipe joint and cable protection pipe installation method

Abstract

To provide a fitting for a cable protection pipe and a method for constructing the cable protection pipe capable of improving workability and construction quality.SOLUTION: A fitting for a cable protection pipe comprises: a cylindrical fitting body 50; pipe connection portions 52 provided at end portions of the fitting body, and capable of connecting another pipe in a state in which it is bent with respect to an axial direction of the fitting body; and a mark 70 provided on the fitting body or an outer circumferential surface of the respective pipe connection portions, and indicating an allowable bending angle of the other pipe with respect to the axial direction of the fitting body. The mark may be provided by pasting a rectangular seal 72 onto the fitting body. By providing a mark by pasting the seal, the mark can be easily provided at a desired position of the fitting.SELECTED DRAWING: Figure 7

Description

Technical Field

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[0003]

[0001] This invention relates to a joint for a cable protection pipe and a method for constructing a cable protection pipe. In particular, for example, it relates to a joint for a cable protection pipe used for constructing a cable protection pipe through which a cable is inserted, and a method for constructing a cable protection pipe using the same.

Background Art

[0002] An example of a conventional joint for a cable protection pipe is disclosed in Patent Document 1. The joint for a cable protection pipe in Patent Document 1 is a pipe joint that can connect between cable protection pipes that can accommodate a plurality of sheath pipes and do not have a bent pipe portion. The joint body has one or a plurality of short pipe portions without a bent pipe portion, and a plurality of bendable portions (rubber ring receiving ports) provided at the ends of the one or a plurality of short pipe portions.

[0003] Also, another example of a conventional joint for a cable protection pipe is disclosed in Patent Document 2. The joint for a cable protection pipe in Patent Document 2 is an exchange joint for exchanging and connecting body pipes (cable protection pipes) that accommodate sheath pipes through which cables are inserted. It has a cylindrical joint body having an inner diameter capable of receiving a body pipe member, a large-diameter portion formed of an elastic material such as rubber or elastomer and externally fitted and fixed to the end of the joint body, and a cylindrical joint member having an inner diameter substantially the same as the outer diameter of the body pipe member and protruding axially outward from the end of the joint body, and a tightening member provided on the outer peripheral surface of the small-diameter portion. This joint member has a folded-back portion that is folded back so as to enter the large-diameter portion at the connecting portion between the large-diameter portion and the small-diameter portion.

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technologies described in Patent Documents 1 and 2 allow for the connection of a cable protection conduit joint to another pipe while it is bent. However, with the technologies described in Patent Documents 1 and 2, it is difficult to determine the degree of bending at which the cable protection conduit joint and the other pipe are connected. As a result, when connecting a cable protection conduit joint to another pipe, the bending angle may exceed the allowable bending angle (the maximum bending angle at which the conduit can be bent appropriately without impairing its function as a cable protection conduit), which can lead to problems with the quality of the cable protection conduit installation.

[0005] Therefore, the main objective of this invention is to provide a novel joint for cable protection conduits and a method for installing cable protection conduits.

[0006] Another object of this invention is to provide a joint for cable protection conduits and a method for installing cable protection conduits that can improve workability and installation quality when installing cable protection conduits. [Means for solving the problem]

[0007] The first invention is a cable protection pipe joint used in the construction of a cable protection pipe through which a cable is inserted, comprising: a cylindrical joint body; a pipe connection portion provided at the end of the joint body, which allows connection of another pipe while the pipe is bent relative to the axial direction of the joint body; and a mark provided on the outer surface of the joint body or the pipe connection portion, which indicates the allowable bending angle of the other pipe relative to the axial direction of the joint body.

[0008] In the first invention, the cable protection conduit joint is used in the construction of a cable protection conduit through which a cable is inserted either directly or through a sheath conduit. The cable protection conduit joint comprises a cylindrical joint body and a pipe connection portion provided at the end of the joint body. This pipe connection portion allows for the connection of another pipe while it is bent relative to the axial direction of the joint body. Furthermore, the outer surface of the joint body or the pipe connection portion is provided with markings indicating the allowable bending angle of the other pipe relative to the axial direction of the joint body.

[0009] According to the first invention, since it is equipped with a mark indicating the allowable bending angle, the installer or construction manager can easily visually confirm that the installation is being carried out within the allowable bending angle. Therefore, the workability when installing the cable protection conduit can be improved, and excessive bending can be prevented, thereby improving the quality of the cable protection conduit installation. This leads to the prevention of excessive bending and ensures that the cable can be routed properly.

[0010] The second invention is dependent on the first invention, and the mark is provided by attaching a seal to the outer surface of the joint body or pipe connection.

[0011] According to the second invention, a mark can be easily provided on the joint for the cable protection conduit.

[0012] The third invention is a method for installing a cable protection pipe using a cable protection pipe joint according to the first or second invention, comprising the steps of (a) inserting the end of another pipe into the pipe connection portion of the cable protection pipe joint, and (b) bending the other pipe and the cable protection pipe joint relative to each other so that they fit within the allowable bending angle indicated by the mark on the cable protection pipe joint.

[0013] The third invention provides the same effects as the first invention, improving work efficiency when installing cable protection conduits and improving the quality of cable protection conduit installation.

[0014] The fourth invention is dependent on the third invention, and in step (b), a linear member or laser beam is used to confirm that the bending angle between the other pipe and the cable protection pipe fitting is within the allowable bending angle.

[0015] According to the fourth invention, excessive bending of the cable protection tube is more reliably prevented, and the installation quality of the cable protection tube is further improved. [Effects of the Invention]

[0016] According to the present invention, since there is a mark indicating the allowable bending angle, a constructor or a construction manager can easily visually confirm that the construction is being carried out within the allowable bending angle. Therefore, the workability during the construction of the cable protection pipe can be improved, and over-bending can be prevented to improve the construction quality of the cable protection pipe. This leads to the occurrence of no excessive bending and ensures the wire passing property of the cable.

[0017] The above object, other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the embodiments made with reference to the drawings.

Brief Description of the Drawings

[0018] [Figure 1] It is an illustrative diagram showing a cable protection pipe line constructed using a joint for a cable protection pipe according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view showing a longitudinal section of the cable protection pipe line cut in the radial direction. [Figure 3] It is an illustrative diagram schematically showing an example of a protection pipe unit. [Figure 4] It is a cross-sectional view showing a longitudinal section of the protection pipe unit cut in the radial direction at the alignment member part. [Figure 5] It is an illustrative diagram showing an example of a body pipe member, where (A) shows the external appearance and (B) shows the longitudinal section cut in the axial direction. [Figure 6] It is an illustrative diagram showing an example of a sheath pipe member, where (A) shows the external appearance and (B) shows the longitudinal section cut in the axial direction. [Figure 7] It is a plan view showing a joint for a cable protection pipe. [Figure 8] It is a cross-sectional view showing the cross-section of the joint for a cable protection pipe cut along line VIII-VIII in FIG. 7. [Figure 9] It is a cross-sectional view showing a state where another pipe is connected to the joint for a cable protection pipe in the maximum bending state. [Figure 10] It is a cross-sectional view showing a body pipe handling unit provided with a joint for a cable protection pipe. [Figure 11]It is an explanatory diagram schematically showing a state of constructing a cable protection pipeline. [Figure 12] It is an explanatory diagram showing a state when another pipe is bent and connected to a joint for a cable protection pipe. [Figure 13] It is an explanatory diagram schematically showing a state when body pipes are exchanged and connected using a joint for a cable protection pipe near a handhole on the end point side. [Figure 14] It is an explanatory diagram schematically showing an operation procedure following FIG. 13.

Embodiments for Carrying Out the Invention

[0019] Referring to FIGS. 1 and 2, a joint 10 for a cable protection pipe (hereinafter simply referred to as "joint 10"), which is an embodiment of the present invention, is used for constructing a body pipe 104 which is an example of a cable protection pipe in the construction of a cable protection pipeline 100 for laying cables (not shown) such as communication cables and power cables underground. As will be described in detail later, the joint 10 is used to form a bent portion (curved pipe portion) in the body pipe 104 or as an exchange joint for exchanging and connecting the body pipes 104.

[0020] The cable protection pipeline 100 includes a plurality of small-diameter sheath pipes 102 through which cables are inserted, and a large-diameter body pipe 104 that houses and protects these sheath pipes 102, and is constructed using a protection pipe unit 12, a joint 10, and the like. As will be described later, each of the sheath pipes 102 is constituted by axially connecting a plurality of sheath pipe members 22, 86, 96, 120, and the body pipe 104 is constituted by axially connecting a plurality of body pipe members 20, 80, 84, 88, 122 and the joint 10.

[0021] First, an example of a protective conduit unit 12, which is one of the main components used in the construction of the cable protection conduit 100, will be described. As shown in Figures 3 and 4, the protective conduit unit 12 forms the cable protection conduit 100 by connecting its axial ends together to create a continuous structure, and includes a body conduit member 20, a plurality of sheath conduit members 22 housed inside the body conduit member 20 in a predetermined arrangement, and an alignment member 24 that slidably holds these sheath conduit members 22 in a predetermined arrangement.

[0022] As shown in Figure 5, the body pipe member 20 is a straight tubular member that constitutes the body pipe 104 and has the strength to withstand external forces such as earth pressure. Specifically, the body pipe member 20 includes a cylindrical straight pipe section 26 and is made of synthetic resin such as polyvinyl chloride, polyethylene, and polypropylene. An enlarged rubber ring socket 28 is formed at one end of the straight pipe section 26, and a socket 30 is formed at the other end. A rubber ring groove is formed on the inner circumferential surface near the tip of the rubber ring socket 28, and a rubber ring 32 for watertight sealing is fitted into this rubber ring groove. The length of the body pipe member 20 is, for example, 5210 mm. The inner diameter of the straight pipe section 26 of the body pipe member 20 is, for example, 250 mm, and its outer diameter is, for example, 267 mm. The body pipe 104 is formed by inserting the socket 30 of another body pipe member 20 into the rubber ring socket 28 and joining them with a rubber ring.

[0023] As shown in Figure 6, the sheath tube member 22 is a straight tubular member that constitutes a sheath tube 102 that individually secures multiple cable housing spaces within the body tube 104, and has a certain degree of flexibility. In this embodiment, eight sheath tube members 22a and six sheath tube members 22b are housed inside the body tube member 20 in a predetermined arrangement (see Figures 3 and 4). When it is not necessary to distinguish between sheath tube members 22a and sheath tube members 22b in the explanation, they will simply be referred to as sheath tube members 22. The same applies to the other sheath tube members 86, 96, and 120.

[0024] Specifically, the sheath tube member 22 includes a cylindrical straight pipe section 34 and is made of synthetic resin such as polyvinyl chloride, polyethylene, and polypropylene. An enlarged adhesive socket 36 is formed at one end of the straight pipe section 34, and a socket 38 is formed at the other end. The length of the sheath tube member 22 is, for example, 5110 mm. The inner diameter of the sheath tube member 22a is, for example, 50 mm, and the inner diameter of the sheath tube member 22b is, for example, 30 mm. Such sheath tube members 22 are joined together by inserting the socket 38 of one sheath tube member 22 into the adhesive socket 36 of the other sheath tube member 22 and bonding them together.

[0025] Furthermore, as shown in Figures 3 and 4, the alignment member 24 holds each sheath tube member 22 within the body tube member 20 in a predetermined arrangement. The alignment member 24 is formed in a disc shape from a soft material such as sponge and is positioned at both ends of the straight pipe portion 26 of the body tube member 20 so as to be movable in the axial direction and rotatable around its axis. The alignment member 24 has a plurality of through holes 40, and the corresponding sheath tube member 22 is inserted through each through hole 40 so as to be slidable in the axial direction.

[0026] Next, the configuration of the joint 10 will be specifically described with reference to Figures 7 and 8. As shown in Figures 7 and 8, the joint 10 comprises a joint body 50 and pipe connection portions 52 provided at both ends of the joint body 50. The pipe connection portion 52 is capable of connecting to another pipe while it is bent relative to the axial direction of the joint body 50. In this embodiment, the pipe connection portion 52 is composed of an enlarged socket 62, a joining member 54, and fastening members 56 and 58, which will be described later.

[0027] The joint body 50 is a straight tubular pipe member formed from synthetic resins such as polyvinyl chloride, polyethylene, and polypropylene, and has sufficient strength to withstand external forces such as earth pressure. The joint body 50 comprises a cylindrical straight pipe section 60 and enlarged receiving openings 62 formed at both ends of the straight pipe section 60, having a larger inner diameter than the straight pipe section 60. The length of the joint body 50 is, for example, 500 mm. Furthermore, the straight pipe section 60 of the joint body 50 has an inner diameter capable of receiving the straight pipe sections of the body pipe members 80 and 122, which will be described later, for length adjustment and terminal use, and the inner diameter of the straight pipe section 60 of the joint body 50 is set to be slightly larger than the outer diameter of the straight pipe sections of the body pipe members 80 and 122.

[0028] A cylindrical joint member 54, made of an elastic material such as rubber or elastomer, is attached to both ends of the joint body 50. For the joint member 54, it is preferable to use one similar to the joint member described in Japanese Patent Publication No. 2017-161070. The configuration of the joint member 54 will be briefly described below, but for details, please refer to Japanese Patent Publication No. 2017-161070.

[0029] The connecting member 54 includes a larger diameter portion 64, a smaller diameter portion 66, and a folded portion 68 formed at the connection between the larger diameter portion 64 and the smaller diameter portion 66. The axial length of the connecting member 54 is, for example, 110 mm, and its thickness is, for example, 5 mm. The axial length of the entire joint 10 when this connecting member 54 is attached to both ends of the joint body 50 is, for example, 608 mm.

[0030] The larger diameter portion 64 of the connecting member 54 has an inner diameter approximately the same as the outer diameter of the enlarged socket 62 of the joint body 50, and is fitted onto the tip of the enlarged socket 62. An attachment groove 64a for attaching the tightening member 56 is formed on the outer circumferential surface of this larger diameter portion 64. On the other hand, the smaller diameter portion 66 of the connecting member 54 has an inner diameter approximately the same as the outer diameter of the straight pipe portion of the various body pipe members 20, 80, 84, and 122, which will be described later, and extends axially outward from the pipe end of the joint body 50. An attachment groove 66a for attaching the tightening member 58 is formed on the outer circumferential surface of this smaller diameter portion 66.

[0031] Furthermore, the folded portion 68 of the joining member 54 is formed by folding the connecting portion between the larger diameter portion 64 and the smaller diameter portion 66 in a roughly S-shape so that it fits inside the larger diameter portion 64. Having such a folded portion 68 provides leeway when the joining member 54 bends, thereby improving the bending performance of the joint 10.

[0032] Furthermore, fastening members (fastening bands) 56, 58 made of stainless steel or synthetic resin are attached to the mounting grooves 64a, 66a formed on the outer circumferential surfaces of the larger diameter portion 64 and the smaller diameter portion 66 of the joining member 54, respectively. The fastening members 56, 58 are annular bands having bolt tightening mechanisms 56a, 58a, and their inner diameter (tightness) can be arbitrarily adjusted. However, the fastening members 56, 58 may also have other fastening mechanisms such as cable tie mechanisms. Also, the larger diameter portion 64 of the joining member 54 and the joint body 50 do not necessarily need to be fixed using the fastening members 56, and may be fixed by adhesive bonding or other means.

[0033] The tightening member 58, which is attached to the small-diameter portion 66 of the connecting member 54, is left untightened, that is, loose or removed, when inserting or sliding the body pipe members 20, 80, 84, 122 into the joint 10. The tightening member 58 is then tightened when fixing the axial position of the joint 10 and the body pipe members 20, 80, 84, 122. When the tightening member 58 is untightened, the resistance of the connecting member 54 acting on the body pipe members 20, 80, 84, 122 is small, so the body pipe members 20, 80, 84, 122 can be easily inserted or slid by hand. By tightening the tightening member 58, the body pipe members 20, 80, 84, 122 and the small-diameter portion 66 can be securely fixed.

[0034] As shown in Figure 9, the pipe connection portion 52 of such a joint 10 can be connected to other pipes (body pipe members 80, 84, etc.) while they are bent relative to the axial direction of the joint body 50. In this embodiment, a folded portion 68 is formed on the joining member 54, and the socket formed at the end of the joint body 50 is made into an enlarged socket 62. By increasing the gap between the inner surface of the enlarged socket 62 and the outer surface of the other pipe, it is possible to connect other pipes at each of the pipe connection portions 52 with respect to the axial direction of the joint body 50 at a maximum bending angle of approximately 6 degrees (allowable bending angle θ). That is, the allowable bending angle θ (i.e., the maximum bending angle that can be bent appropriately without impairing the function as a cable protection pipe), which is the bending angle that is permitted in the design of the pipe connection portion 52, is set to approximately 6 degrees. Therefore, the joint 10 can have a maximum bending angle of approximately 12 degrees when the pipe connection portions 52 on both sides are combined.

[0035] Here, when connecting the joint 10 to another pipe in a bent state, it is not possible to know the degree of bending angle at which they are connected, and a situation may occur where they are bent too much beyond the allowable bending angle θ. Therefore, in this embodiment, by providing a mark 70 on the joint 10 that indicates the allowable bending angle θ of the other pipe with respect to the axial direction of the joint body 50, the workability when installing the body pipe 104, which is an example of a cable protection pipe, is improved, and the quality of installation of the body pipe 104 (and by extension the cable protection conduit 100) is improved.

[0036] As shown in Figure 7, the markers 70 are provided on the outer circumferential surfaces of both ends of the joint body 50, corresponding to each of the pipe connection portions 52. In this embodiment, the markers 70 are provided on the joint body 50 by attaching a rectangular seal 72 to the joint body 50. By providing the markers 70 by attaching the seal 72, the markers 70 can be easily provided at the desired position on the joint 10. In this embodiment, the markers 70 are also provided on the top of the joint body 50, and the markers 70 are used to control the lateral bending of the body pipe 104. Specifically, the markers 70 include a reference line 70a extending along the axial direction of the joint body 50, and two boundary lines 70b that are inclined with respect to the reference line 70a at an allowable bending angle θ, i.e., indicating the allowable bending angle θ.

[0037] By using the boundary line 70b (i.e., the allowable bending angle θ) indicated by the marker 70 as a guide for piping, the installer can easily visually confirm that the other pipes are installed within the allowable bending angle θ relative to the joint 10. Therefore, work efficiency is improved, and excessive bending of the body pipe 104 can be prevented, thereby improving the installation quality of the body pipe 104. In addition, by piping the other pipes so that their axial direction aligns with the boundary line 70b, it is easy to see that the formed body pipe 104 is bent at a predetermined bending angle (approximately 6 degrees in this embodiment), that is, that the body pipe 104 is installed with a predetermined radius of curvature.

[0038] As described above, such a joint 10 can be used to form a curved section (bent section) in the body pipe 104, or as a connecting joint for exchanging the body pipe 104.

[0039] As shown in Figure 10, when the joint 10 is used as a connecting joint, a length-adjusting body pipe member 80 is inserted from one end thereof, thereby forming a body pipe connecting unit 82. The length-adjusting body pipe member 80 is a body pipe member manufactured at the construction site by cutting the body pipe member 20 to the required length, and both ends thereof are spigots. The axial length of the body pipe connecting unit 82 can be freely changed by sliding the joint 10 or the body pipe member 80.

[0040] Furthermore, when forming a curved pipe section using the joint 10, a body pipe member 84 for bending (see Figure 12) is used as a body pipe member connected to one end of the joint 10 (the upstream end in the construction direction). The body pipe member 84 for bending is a body pipe member with sockets at both ends, which is manufactured at the construction site by cutting off the rubber ring socket 28 of the body pipe member 20 to the required length.

[0041] Next, with reference to Figures 11-14 along with Figure 1, a construction method for installing a cable protection conduit 100, including the body pipe 104, in a predetermined construction section using the protective pipe unit 12 and joints 10, will be described. Note that in Figures 11, 13, and 14, for the sake of simplifying the drawings, one representative sheath pipe member 22, 86, 96, 120 (sheath pipe 102) is shown, and the other sheath pipe members 22, 86, 96, 120 are not shown. The construction method for the cable protection conduit 100 will be described below, but for details other than the explanation of the construction of the curved pipe section, please refer to Japanese Patent Publication No. 2017-161070.

[0042] When constructing the cable protection conduit 100, first, a first handhole 106a is provided at one end of the construction section, and a second handhole 106b is provided at the other end. Then, the cable protection conduit 100 is constructed sequentially, starting from the first handhole 106a and extending to the vicinity of the second handhole 106b.

[0043] To put it simply, as shown in Figure 11, first, a bolt-fixed lotus pipe 112, which has multiple sheath pipe duct sleeves 110, is attached to the duct sleeve 108 of the first handhole 106a on the starting side. Then, a terminal sheath pipe member 86 is inserted into each of the sheath pipe duct sleeves 110 and connected, and a terminal body pipe member 88 is inserted into the duct sleeve 108 and connected. After connecting the terminal sheath pipe members 86 and body pipe members 88 to the first handhole 106a, the protective pipe unit 12 (i.e., each of the multiple sheath pipe members 22 and body pipe members 20) is connected sequentially, and the cable protection conduit 100 is constructed up to the vicinity of the second handhole 106b.

[0044] During this construction process, if a curved section is to be formed in the cable protection conduit 100, the body pipe 104 is bent in the desired direction using the joint 10. The sheath pipe 102 is bent by its own flexibility.

[0045] Specifically, first, a sheath tube member for bending (not shown) and a body tube member 84 are manufactured. The body tube member for bending 84 can be manufactured by cutting off the rubber ring socket 28 of the body tube member 20 to the required length, as described above. The sheath tube member for bending can be manufactured by cutting the sheath tube member 22, but its length should be such that, when one end of the joint 10 is connected to the body tube member for bending 84, the tip of the sheath tube member for bending protrudes slightly from the other end of the joint 10. In other words, when one end of the joint 10 is connected to the body tube member for bending 84, the joint 10 is provided in place of the rubber ring socket 28 of the body tube member 20, and the sheath tube member for bending extends across the body tube member 84 and the joint 10.

[0046] Once the bendable sheath tube member and body tube member 84 are ready, one end of the bendable sheath tube member is connected to the corresponding sheath tube member 22, and one end of the bendable body tube member 84 is connected to the body tube member 20. At this time, the bendable body tube member 84 is routed so that the printing 90 indicating manufacturing information etc. is at the top.

[0047] Next, as shown in Figure 12, one end of the joint 10 is connected to the other end of the bending body pipe member 84. That is, the body pipe member 84 and the joint 10 are connected by inserting the socket of the body pipe member 84 into the pipe connection portion 52 on one end of the joint 10 and tightening the tightening member 56. At this time, the joint 10 is installed so that the reference line 70a indicated by the marking 70 is at the zenith. By connecting the joint 10 so that the reference line 70a is in a straight line with the marking 90 on the body pipe member 84, the axial directions of the body pipe member 84 and the joint 10 are aligned, so that the socket of the body pipe member 84 can be smoothly inserted into the pipe connection portion 52 of the joint 10.

[0048] Next, the protective pipe unit 12 is connected to the other end of the joint 10 and the sheath pipe member for bending. That is, the other end of the sheath pipe member for bending is connected to the corresponding sheath pipe member 22. The joint 10 and the body pipe member 20 are then connected by inserting the opening 30 of the body pipe member 20 into the pipe connection part 52 on the other end of the joint 10 and tightening the tightening member 58. At this time, the body pipe member 20 should be piped so that the printing 92 indicating manufacturing information, etc., is at the top, similar to the body pipe member 84 for bending.

[0049] Then, after connecting the body pipe members 20 and 84 to both ends of the joint 10, the joint 10 is bent relative to the bending body pipe member 84, and the body pipe member 20 is bent relative to the joint 10, thereby bending the body pipe 104 in the desired direction. The sheath pipe 102 curves and flexes in accordance with the bending of the body pipe 104.

[0050] When bending the joint 10 and the body pipe members 20 and 84 relative to each other, the boundary line 70b (i.e., the allowable bending angle θ) indicated by the mark 70 on the joint 10 should be used as a guide, and the bending should be done so that it remains within the allowable bending angle θ. For example, a linear member 130 such as a ruler and a measuring tape, or a laser beam, can be placed along the markings 90 and 92 on the body pipe members 20 and 84 (i.e., the axial direction of the body pipe members 20 and 84), and the joint 10 and the body pipe members 20 and 84 should be bent relative to each other while confirming that the bending angle between the joint 10 and the body pipe members 20 and 84 is within the allowable bending angle θ. This reliably prevents overbending of the body pipe 104, thereby improving the construction quality of the body pipe 104. Furthermore, overbending of the sheath pipe 102 routed inside the body pipe 104 is also prevented, improving the construction quality of the sheath pipe 102, and consequently improving the overall construction quality of the cable protection conduit 100. Furthermore, when bending the joint 10 and the body pipe members 20 and 84 relative to each other, the body pipe 104 can be constructed with a predetermined radius of curvature by piping so that the markings 90 and 92 on the body pipe members 20 and 84 and the boundary line 70b indicated by the marking 70 on the joint 10 are aligned in a straight line.

[0051] Once the construction of the curved section of the cable protection conduit 100 is complete, the connection work of the protection conduit unit 12 is continued, and the cable protection conduit 100 is constructed up to the vicinity of the second handhole 106b. Then, once the cable protection conduit 100 has been constructed up to the vicinity of the second handhole 106b, the construction of the end section of the cable protection conduit 100 is carried out, as shown in Figures 13 and 14.

[0052] Specifically, in the same manner as on the first handhole 106a side, a bolt-fixed lotus pipe 112 is attached to the duct sleeve 108 provided on the second handhole 106b. Then, a terminal sheath pipe member 120 is slidably inserted into each sheath pipe duct sleeve 110 of the bolt-fixed lotus pipe 112, and the opening of the terminal body pipe member 122 is inserted into the rubber ring receiving opening of the duct sleeve 108 and they are joined together with a rubber ring.

[0053] Then, as shown in Figure 13, once the cable protection conduit 100 has been constructed, leaving a predetermined section unfinished, the sheath pipe 102 and the body pipe 104 are connected.

[0054] To put it simply, first, measure the length of the remaining section and then manufacture a length-adjusting sheath pipe member 96 and a body pipe member 80 with the corresponding length. The length-adjusting sheath pipe member 96 and body pipe member 80 can be manufactured by cutting the sheath pipe member 22 and body pipe member 20 to the required length as needed. Then, prepare a body pipe exchange unit 82 (see Figure 10) which connects the length-adjusting body pipe member 80 and the joint 10.

[0055] Once the body pipe exchange unit 82 and the like are ready, as shown in Figure 14, one end of the length-adjusting sheath pipe member 96 is connected to the corresponding sheath pipe member 22, and one end of the body pipe exchange unit 82 is connected to the body pipe member 20. The other end of the length-adjusting sheath pipe member 96 is connected to the terminal sheath pipe member 120, and the other end of the body pipe exchange unit 82 is connected to the terminal body pipe member 122. That is, each sheath pipe member 120 is slid outwards in sequence, and the other end of the corresponding sheath pipe member 96 is inserted into the adhesive receiving end of each sheath pipe member 120, and they are bonded together. After that, the joint 10 is slid outwards to extend the body pipe exchange unit 82, and the end of the terminal body pipe member 122 is inserted into the pipe connection portion 52 of the joint 10. Then, the exchange connection is completed by tightening the tightening member 58.

[0056] Here, when connecting the body pipes 104, there may be cases where the pipe axes of the joint 10 and the end body pipe member 122 are misaligned, and the Socket of the body pipe member 122 is inserted into the pipe connection portion 52 of the joint 10. In this case, the joint 10 is bent relative to the length-adjusting body pipe member 80, but as with the construction of the curved pipe section described above, it is best to bend it so that it stays within the allowable bending angle θ, using the boundary line 70b indicated by the mark 70 on the joint 10 as a guide. This reliably prevents the body pipe 104 from being bent too much, thus improving the construction quality of the body pipe 104.

[0057] Through the above construction work, a series of cable protection conduits 100 connecting the two handholes 106a and 106b is formed, as shown in Figure 1. Subsequently, cables are inserted into the interior (cable housing space) of each sheath pipe 102 of the cable protection conduit 100 as appropriate.

[0058] As described above, according to this embodiment, since the joint 10 is equipped with a mark 70 indicating the allowable bending angle θ, the installer or construction manager can easily visually confirm that the installation is being carried out within the allowable bending angle θ. Therefore, the workability when installing the body pipe 104 can be improved, and excessive bending can be prevented, thereby improving the installation quality of the body pipe 104. In addition, damage to the sheath pipe 102 housed inside the body pipe 104 can be prevented, and the overall installation quality of the cable protection conduit 100 is also improved. Furthermore, since excessive bending does not occur in the cable protection conduit 100 (sheath pipe 102 and body pipe 104), cable routing is ensured.

[0059] Furthermore, according to this embodiment, since the marker 70 is provided by attaching the seal 72, the marker 70 can be easily provided on the joint 10.

[0060] In the above-described embodiment, a body pipe 104 that houses the cable via a sheath pipe 102 was illustrated as an example of a cable protection pipe to which the joint 10 is applied. However, the cable can also be directly housed inside the cable protection pipe. In other words, the cable protection pipe to which the joint for cable protection pipes according to this invention is applied includes both those that directly house the cable and those that house the cable via a sheath pipe. Furthermore, the specific embodiments of the sheath pipe member and the body pipe member can also be modified as appropriate.

[0061] Furthermore, in the above-described embodiment, pipe connection portions 52 for flexibly connecting other pipes are provided at both ends of the joint body 50, but the invention is not limited thereto. The cable protection pipe joint according to this invention may have a pipe connection portion for flexibly connecting other pipes at only one end of the joint body.

[0062] Furthermore, in the above-described embodiment, the pipe connection portion 52 is composed of an enlarged diameter socket 62, a joining member 54, and fastening members 56, 58, but is not limited thereto. The pipe connection portion only needs to be capable of connecting other pipes in a bendable manner, and may be composed of, for example, a rubber ring socket.

[0063] Furthermore, in the above embodiment, the marker 70 includes a reference line 70a, but the reference line 70a is not necessarily required. The marker may also include an indicator showing a predetermined angle (for example, approximately 3 degrees) within the range of allowable bending angles. Moreover, the specific characteristics of the reference line 70a and boundary lines 70b included in the marker 70, such as their length and thickness, can also be changed as appropriate. For example, in the above embodiment, the two boundary lines 70b are provided so as to straddle the enlarged socket 62 and the straight pipe section 60 and intersect, but the two boundary lines 70b can also be provided so as to fit within the enlarged socket 62 without intersecting. Also, for example, the reference line 70a can be provided so as to extend over approximately the entire length of the joint body 50.

[0064] Furthermore, in the above-described embodiment, the marker 70 was provided by attaching a seal 72 to the joint body 50, but the invention is not limited to this. The marker can also be directly displayed on the joint body or pipe connection part by handwriting or printing with an oil-based pen, or it can be engraved on a raised or recessed part, or it can be provided by a combination of attaching a seal, direct display, and engraving. When the marker is formed on a raised part, the marker can also be used as a guide part for a linear member.

[0065] Furthermore, in the above-described embodiment, the marker 70 was placed on the top of the joint 10 and used to manage the lateral bending of the cable protection tube, but the invention is not limited to this. For example, the marker can also be placed on the side of the joint for the cable protection tube and used to manage the vertical bending of the cable protection tube.

[0066] Please note that the specific dimensions and other numerical values ​​mentioned above are merely examples and can be changed as needed according to product specifications and other requirements. [Explanation of Symbols]

[0067] 10 ... Fittings for cable protection conduits 12 ... Protective tube unit 20, 80, 84, 88, 122 ... Body pipe components 22, 86, 96, 120 ... Sheath pipe member 50 ... Fitting body 52 ... Pipe connection 54 ... Joining member 56, 58 ... fastening members 70... Landmark 72... Seal 82...Body pipe exchange unit 100 ... Cable protection conduit 102...sheath tube 104... Body tube (cable protection tube)

Claims

1. A cable protection pipe joint used in installing a cable protection pipe through which a cable is inserted, A cylindrical joint body, a pipe connection portion provided at an end of the joint body and capable of connecting another pipe in a state where the pipe is bent in the axial direction of the joint body; and A joint for a cable protection pipe, comprising a mark provided on the outer surface of the joint body or the pipe connection portion, which mark indicates the allowable bending angle of the other pipe relative to the axial direction of the joint body.

2. 2. The joint for a cable protection pipe according to claim 1, wherein the mark is provided by attaching a seal to an outer peripheral surface of the joint body or the pipe connection portion.

3. A method for installing a cable protection pipe using the cable protection pipe joint according to claim 1 or 2, (a) inserting an end of another pipe into the pipe connection portion of the cable protection pipe joint; and (b) A cable protection pipe installation method including a step of bending the other pipe and the cable protection pipe joint relative to each other so that the allowable bending angle indicated on the mark on the cable protection pipe joint is within the allowable bending angle, using the allowable bending angle indicated on the mark on the cable protection pipe joint as a guide.

4. 4. The cable protection pipe installation method according to claim 3, wherein in the step (b), it is confirmed that the bending angle between the other pipe and the cable protection pipe joint is within the allowable bending angle using a linear member or laser light.

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