Independent wave cable protective pipe, connection structure of female joint member and independent wave cable protective pipe, method for cutting independent wave cable protective pipe, and method for connecting independent wave cable protective pipe and female joint member

Abstract

To provide an independent wave cable protective pipe capable of stably obtaining a shape of a cut end part connectable to a female joint structure, and a connection structure of a female joint member and an independent wave cable protective pipe.SOLUTION: An independent wave cable protective pipe 1 has a circular cross section perpendicular to a pipe axis direction, and is made of rigid polyvinyl chloride resin. An outer surface of the independent wave cable protective pipe 1 has a wave shape in which peaks 3 and valleys 5 are repeated in the pipe axis direction. The outer shape of the peaks 3 is approximately rectangular in the pipe axis direction of the independent wave cable protective pipe 1, and a flat part 9 is formed at the top of the peak. In other words, the top of the peaks 3 is formed linearly in the pipe axis direction of the independent wave cable protective pipe 1. Also, an approximately U-shaped groove-like recess 7 is provided in the center of the flat part 9 of the peak 3 in the pipe axis direction of the independent wave cable protective pipe 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an independent wave cable protection tube that can be stably connected to a female joint structure, a connection structure between a female joint member and an independent wave cable protection tube, a cutting method for the independent wave cable protection tube, and a connection method between the independent wave cable protection tube and a female joint member. [Background technology]

[0002] Up until now, when burying cables in utility trenches, rigid polyvinyl chloride cable protection tubes have been used to protect the cables. Cable protection tubes need to have a certain degree of flexibility, so a corrugated shape is formed on the outer periphery of the tube. Such corrugated cable protection tubes are classified into spiral wave, in which the wave shape varies depending on the circumferential position of the tube, and independent wave, in which the tube has the same wave shape in the longitudinal direction at any circumferential position.

[0003] Here, in the case of a cable protection tube made of hard polyvinyl chloride, the cable protection tube may be cut to form a straight-line insertion type male joint structure at the cut portion of the cable protection tube, and then connected to a female joint structure. In this case, if the cable protection tube is helically corrugated, there is a risk of rainwater infiltration from the helical groove at the cut end. For this reason, a cable protection tube having a rectangular independent corrugated shape may be used from the viewpoint of water blocking.

[0004] As such a cable protection tube, for example, Patent Document 1 discloses a cable protection tube that has good flexibility, mechanical strength, and flame retardancy, and does not generate harmful halogen gases or dioxins when burned.

[0005] Also, Patent Document 2 discloses a corrugated flexible tube that improves the piping workability of the corrugated flexible tube and the fluid pipe by minimizing the decrease in the bendability of the corrugated flexible tube itself through a rational arrangement of the corrugated flexible tube and the heat dissipation pipe, while at the same time reducing the size of the pipe in the radial direction and reducing the manufacturing cost. The corrugated flexible tube of Patent Document 2 has straight portions in both the peaks and valleys, and the peaks and valleys have shapes that are inverted and symmetrical with respect to the center line of the slope portion.

[0006] Patent Document 3 also discloses a pipe joint that has excellent waterproofing properties regardless of the unevenness of the outer peripheral surface of the pipe body and allows easy connection of the pipe body. In the pipe connection structure of Patent Document 3, when the corrugated pipe is inserted into the pipe joint, the tapered shape of the retaining claws allows the corrugated pipe to be inserted into the pipe joint without being caught by the retaining claws. When the corrugated pipe is completely inserted and held in the pipe joint, the packing is crushed at the tip of the corrugated pipe. Since the packing has an extremely large amount of deformation, it can follow the tip shape of the corrugated pipe and can reliably stop water. In this state, the retaining claws are caught over the entire circumference of the valley of the corrugated pipe, so the corrugated pipe will not come off the pipe joint.

[0007] Moreover, Patent Document 4 discloses a pipe joint structure different from that of Patent Document 3, which uses a waterproofing member.

[0008] Patent Document 5 discloses a configuration in which multiple flexible tubes are connected between hand holes and inserted into a block-shaped divided member. The block-shaped divided member has a shape divided along a diagonal of a pair of rectangular parallelepipeds, with a spigot at one end and a socket at the other end. Each of the pair of divided members has a flexible tube fitting portion having a semicircular vertical cross section, and when the flexible tube fitting portions of the pair of divided members are placed face to face and overlapped, a flexible tube insertion portion having a circular vertical cross section is formed by the flexible tube fitting portions of both divided members.

[0009] Patent Document 6 discloses a connection structure between a connected independent corrugated pipe, on whose outer circumference many independent waves are arranged in the axial direction, and a cylindrical pipe joint. A ring-shaped rubber packing is fixed to the pipe fitted on the outer circumference near the end of the connecting independent corrugated pipe, sealing between the independent wave surface of the connected independent corrugated pipe and the inner surface of the cylindrical pipe joint, and the cylindrical pipe joint is inserted from the end of the connected independent corrugated pipe to a depth equal to or greater than the ring-shaped rubber packing. Here, the rubber packing in Patent Document 6 is an independent corrugated pipe used as an outer pipe for information cables, etc., and the ring-shaped rubber packing can be easily attached or removed, and sufficient sealing can be achieved by inserting the cylindrical pipe joint with the ring-shaped rubber packing attached to this pipe.

[0010] [Patent Document 1] JP 2002-5348 A [Patent Document 2] Japanese Patent Application Publication No. 2006-052759 [Patent Document 3] JP 2012-154488 A [Patent Document 4] JP 2023-058250 A [Patent Document 5] JP 2005-057933 A [Patent Document 6] JP 2000-193167 A Summary of the Invention [Problem to be solved by the invention]

[0011] Generally, in the case of rigid PVC flexible cable protection tubes having rectangular independent waves, in order to emphasize flexibility, the valleys are formed in an approximately U-shape or an inverted trapezoid, the pitch on the valley side is shortened, the number of slopes per given length of the product is increased, the length of the slopes is increased, or the difference in diameter between the peaks and valleys is made large. For this reason, in rigid PVC flexible cable protection tubes, cable protection tubes in which the length of the valleys in the tube axial direction is made equal to the length of the peaks, and the peaks and valleys are alternately inverted and symmetrical have not been used much.

[0012] Here, in a male joint structure such as a large-diameter rigid PVC pipe, the connection between cable protection pipes with large pipe diameters and approximately trapezoidal rectangular independent waves poses a problem of complicated joint structures. To avoid this problem, a connection method in which a rubber packing is attached to the valley of the cable protection pipe and this is inserted into a cylindrical female structure part that gradually narrows toward the center of the joint to connect the cable protection pipe and the joint has been adopted in many cases because it makes it easy to connect the cable protection pipe and the joint.

[0013] Such a male joint structure requires cutting a long cable protection tube to the required length and forming a male joint at the cut end. However, when the cable protection tube is cut at the valley portion, the end of the cut valley portion protrudes in the tube axial direction inside the female joint, which may cause an obstacle when inserting the cable or damage the surface of the cable.

[0014] On the other hand, when cutting the cable protection tube at the crest, the tube diameter becomes larger than when cutting at the valley, making cutting difficult. Furthermore, the cut surface of the cable protection tube is not perpendicular to the tube axis direction, and the cut positions of the linear parts of the crest may differ between the upper and lower sides of the cable protection tube. When a joint structure is provided near such an obliquely cut cut end, the cut positions at the cut end may differ depending on the location, and the dimensions and strength of the joint structure may be unstable.

[0015] The above-mentioned Patent Documents 1 to 6 do not take into consideration the method of cutting at the peaks in this way. For this reason, there is a demand for an independent wave cable protection tube that can obtain a cut end that can be stably connected to a female joint structure even when cut at the peaks.

[0016] The present invention has been made in consideration of such problems, and aims to provide an independent-wave cable protection tube that can stably obtain a cut end shape that can be connected to a female joint structure, a connection structure between a female joint member and an independent-wave cable protection tube, a method for cutting the independent-wave cable protection tube, and a method for connecting the independent-wave cable protection tube to a female joint member. [Means for solving the problem]

[0017] In order to achieve the above-mentioned object, the first invention is an independent wave cable protection pipe made of a rigid polyvinyl chloride resin having a circular cross section perpendicular to the tube axis direction and a corrugated shape in which peaks and valleys are repeated in the tube axis direction, the peaks are rectangular with flat parts at their tops in the tube axis direction of the independent wave cable protection pipe, and a groove-shaped recess in a substantially U-shape is provided in the center of the flat part of the peak, and the groove-shaped recess is provided continuously on all peaks or on at least two or more peaks adjacent in the tube axis direction. When the groove-shaped recess is provided in this way, it can be used as a cutting groove or a ring-shaped water-stopping member arrangement part of a male joint structure.

[0018] The groove-like recess may be provided continuously on at least three or more of the peaks adjacent to each other in the tube axial direction.

[0019] In the tube axial direction of the independent wave cable protective tube, a slope portion connecting the valley portion and the peak portion is formed between the valley portion and the peak portion, and the length from the center to the center of the slope portion sandwiching the peak portion is longer than the length from the center to the center of the slope portion sandwiching the valley portion, and the valley portion and the slope portions on both sides of the valley portion are formed in an approximately U-shape; alternatively, the valley portion has a straight portion that is shorter than the flat portion of the peak portion, and the valley portion and the slope portions on both sides of the valley portion are formed in an inverted trapezoid shape.

[0020] A male joint structure may be formed at the end of the independent wave cable protection tube, which has either a structure in which the independent wave cable protection tube is cut at a groove-shaped recess provided in the center of two or more consecutive crests provided at any position of the independent wave cable protection tube, and a rubber water-stopping member is attached to the valley portion adjacent to the cut crest portion, or in addition to the rubber water-stopping member, another small rubber water-stopping member is further provided in the groove-shaped recess of the crest portion adjacent to the valley portion.

[0021] In the tube axial direction of the independent wave cable protection tube, a slope portion connecting the valley portion and the crest portion is formed between the valley portion and the crest portion, the crest portion and the valley portion are formed in a straight line of approximately the same length in the tube axial direction, and the wave shape in which the crest portion and the valley portion are connected by the slope portion may have an approximately trapezoidal rectangular independent wave shape that is inverted symmetrically with respect to a center line passing through the slope portion.

[0022] The independent wave cable protection tube has a pitch of the valley portion, which corresponds to half the pitch of the corrugated shape, of 20 mm or more, is cut at the groove-shaped recess provided in the center of the peak portion at any position of the independent wave cable protection tube, and a ring-shaped or approximately C-shaped resin anti-slip ring is attached to the valley portion adjacent to the cut peak portion, and the anti-slip ring has a first locking piece that expands diagonally and a second locking piece that is parallel to the tube axial direction, and the first locking piece and the second locking piece have a structure that extends from a base portion that is continuous in the circumferential direction, and a rubber water-stopping member is provided in at least one of the groove-shaped recess of the peak portion adjacent to the valley portion or the next valley portion on the inner side of the tube adjacent to the valley portion, thereby forming a male joint structure at the end of the independent wave cable protection tube.

[0023] The independent wave cable protection tube has an outer tube diameter of 120 mm to 300 mm and a tube thickness appropriately set in the range of 2.0 mm to 3.5 mm. The ratio of the difference in height between the peaks and the valleys to the outer tube diameter of the peaks is 6% to 10%, and the wave pitch of the rectangular wave is 35 mm to 70 mm, thereby reducing the length of the inclined surface portion and the number of the inclined surface portions per given length of the independent wave cable protection tube, and the independent wave cable protection tube can be prevented from excessive flexibility.

[0024] If the ratio of the difference in height between the peaks and valleys to the outer diameter of the tube is less than 6%, the pressure resistance of the cable protection tube will be insufficient, and if it exceeds 10%, the effect of suppressing excessive flexibility will not be obtained and the flexibility will approach that of conventional cable protection tubes. Therefore, in order to simultaneously suppress the excessive flexibility seen in conventional flexible tubes and at the same time satisfy the pressure resistance of the cable protection tube, the ratio of the difference in height between the peaks and valleys to the outer diameter of the tube needs to be between 6% and 10%.

[0025] Furthermore, if the wave pitch is less than 35 mm, the flexibility becomes excessive, and if it exceeds 70 mm, the pressure resistance decreases and the interval between the groove-like recesses becomes too wide, reducing the effect of length adjustment when cutting. Therefore, it is desirable for the wave pitch of the square wave to be 35 mm or more and 70 mm or less. By setting the wave pitch of the square wave in this range, it is possible to suppress excessive flexibility of the cable protection tube while at the same time ensuring the pressure resistance required for the cable protection tube.

[0026] This makes it possible to suppress excessive flexibility when bending the cable protection tube to 5mR or 10mR, eliminating the need to correct the bending angle due to excessive bending, and at the same time, it makes it possible to suppress sagging caused by the upper cable protection tube pressing against the lower cable protection tube when multiple layers are arranged at the pipe entrance.

[0027] In addition, by appropriately setting the tube outer diameter of the independent wave cable protective tube in the range of 120mm to 300mm and the tube thickness in the range of 2.0mm to 3.5mm, respectively, in addition to the flexibility suppression effect, by reducing the value obtained by dividing the difference in height between the peaks and valleys by the tube outer diameter to 6% to 10%, the accommodation cross-sectional area ratio, which is the ratio of the circular cross-sectional area of ​​the tube inner diameter at the valleys of the cable protective tube to the circular cross-sectional area of ​​the tube outer diameter at the peaks, can be set to 59% to 73%. Therefore, in addition to suppressing flexibility, it is possible to obtain an independent wave cable protective tube that improves the accommodation efficiency of the cable protective tube and at the same time improves wire passing properties and heat dissipation properties. In addition, the accommodation cross-sectional area can be set to 60% to 72%. Here, "appropriately set" means that by setting the pipe outer diameter and wall thickness to appropriate values ​​rather than arbitrarily setting them, the difference in height between the peaks and valleys divided by the pipe outer diameter can be set to 6% or more and 10% or less, while the accommodation cross-sectional area ratio can be set to 59% or more and 73% or less. In other words, this means that the accommodation cross-sectional area ratio does not satisfy the above-mentioned values ​​when the tube outer diameter of the independent wave cable protective tube is in the range of 120 mm to 300 mm and the tube wall thickness is in the range of 2.0 mm to 3.5 mm.

[0028] The yield stress of the rigid polyvinyl chloride resin may be 40.5 MPa or more, the depth of the groove-shaped recess provided at the center of the peak is less than half the difference in height between the peak and the valley of the independent wave cable protective tube, the deflection rate as the compressive strength measured by the method specified in the compressive strength test of JIS C 3653 Appendix 1 using the independent wave cable protective tube is 3.5% or less, and the stress generated in the independent wave cable protective tube at a buried depth of 5 m is 13.5 MPa or less, and it may be 1 / 3 or less of the breaking strength of the rigid polyvinyl chloride resin. Here, the yield stress of the rigid polyvinyl chloride resin may be set to any value in the range of 40.5 MPa to 45 MPa, for example, in the range of 42 MPa to 45 MPa.

[0029] According to the first invention, since a groove-shaped recess is provided in a substantially U-shape at the center of the flat portion of the peak portion, when cutting the independent wave cable protection tube, the groove-shaped recess can be used as a guide to perform cutting. Therefore, the peak portion can be cut stably and substantially perpendicularly to the tube axis direction. In particular, when the tube diameter becomes large, it becomes difficult to cut the cable protection tube, and stable cutting is difficult, but cutting of a large-diameter tube that is difficult to cut becomes easy. In this way, since the cut end is not inclined to the tube axis direction, even when a male joint structure is formed, stable strength of the male joint structure formed near the cut end can be ensured. Here, the groove-shaped recess does not mean substantially U-shaped in the strict sense, but also includes, for example, a substantially U-shaped shape.

[0030] In addition, by providing a groove-shaped recess in all the peaks, or by providing a groove-shaped recess in at least two or more consecutive peaks at any position, the cutting position can be set to the center of two or more consecutive peaks. This makes it easier to adjust the length of the cable protection tube, and furthermore, one of the consecutive groove-shaped recesses can be used as a cutting groove, while one or more of the remaining peaks can be used as a ring-shaped water-stopping member placement portion of the male joint structure. For example, by cutting so that a peak with a groove-shaped recess remains at the end to be used as a connection portion, the groove-shaped recess in the first peak can be used for cutting, and a water-stopping member can be placed in the adjacent second peak.

[0031] Furthermore, by providing a groove-like recess in at least three or more consecutive crests at any position, if the cable protection tube is cut at the groove-like recess in the central crest while leaving the crests at both ends, crests having groove-like recesses can be left at the ends of the cut tube on both sides. This makes it possible to place a water-stopping member in the groove-like recess in each cut end.

[0032] Also, forming a groove-like recess in the valley portion causes an obstacle when cutting, but forming a groove-like recess in the peak portion does not cause an obstacle when threading the cable, and does not damage the cable surface when threading the cable. Furthermore, when a male joint structure is provided at the cut end, the cut end has excellent dimensional stability, and at the same time, when the cable is held for cable laying work, if there is a groove-like recess in the center of the peak portion, this has the effect of preventing the cable from slipping, improving workability, etc.

[0033] In addition, the cross section of the cable protection tube is reinforced by the groove-shaped recesses provided in the peaks, which increases the compressive strength and improves the rigidity of the independent wave cable protection tube. Furthermore, by fitting a packing in the groove-shaped recesses, it can also be used as a water-stopping structure.

[0034] In such a shape, the number of slopes can be increased by making the length from center to center of the slopes sandwiching the valley (the length from the center of one slope to the center of the other slope of the slopes sandwiching the valley) shorter than the length from center to center of the slopes sandwiching the peak (the length from the center of one slope to the center of the other slope of the slopes sandwiching the peak). In this case, the valley and the slopes on both sides of the valley may be formed in a substantially U-shape, or the valley and the slopes on both sides of the valley may be formed in an inverted trapezoid shape.

[0035] A male joint structure can be formed by attaching a rubber waterproofing member to the valleys near the cut end. In addition to the rubber waterproofing member attached to the valleys, a small rubber waterproofing member can be provided in the groove-shaped recess of the peak adjacent to the valleys to form a male joint structure with higher waterproofing properties.

[0036] In addition, the peaks and valleys are formed in a straight line shape of approximately the same length in the tube axis direction of the independent wave cable protective tube, and the wave shape in which the peaks and valleys are connected by the slopes forms a wave shape of an approximately trapezoidal rectangular independent wave that is inversion symmetrical with respect to the center line passing through the slopes, so that the tube axis lengths of the valleys and peaks can be made equal. Therefore, the number of slopes can be reduced compared to conventional cable protective tubes with short valleys, so that excessive flexibility can be suppressed. In other words, the inversion symmetric shape is an approximately trapezoidal rectangular independent wave shape that is rotationally symmetrical by 180° with respect to the center point of the slopes.

[0037] For example, as described above, the flexibility can be improved by shortening the length of the valley portion relative to the crest portion, but if the flexibility is too great, there is a problem of a decrease in wire-passing ability due to excessive bending. In response to this, as described above, by making the crest portion and the valley portion inverted symmetrical shape and reducing the number of slope portions per specified length of the product, it is possible to prevent the independent wave cable protective tube from bending too much. As a result, the wire-passing ability of the cable and the pulling eye in the independent wave cable protective tube is improved, and the thermal resistance of the protective tube is reduced, improving heat dissipation.

[0038] Also, by attaching a ring-shaped or substantially C-shaped resin retaining ring to the valley near the cut end of the independent wave cable protection tube, a male joint structure can be formed at the cut end. In this case, if the resin retaining ring has a first locking piece that expands diagonally and a second locking piece that is parallel to the tube axis direction, it can be reliably connected to the female joint structure, and a rubber water-stopping member is provided in the valley, so that water-stopping properties can also be ensured.

[0039] In this case, if the length of the valley in the axial direction of the tube is 20 mm or more, the retaining ring can be easily held in place. For example, if the length of the valley in the axial direction of the tube is less than 20 mm, the angle of the locking piece of the retaining ring becomes too steep, and the locking piece is likely to break when a pulling force is applied.

[0040] In addition, by setting the ratio of the height difference between the peaks and valleys to the outer diameter of the peaks to 6% to 10%, and setting the accommodation cross-sectional area ratio, which is the ratio of the circular cross-sectional area of ​​the inner diameter of the valleys to the circular cross-sectional area of ​​the outer diameter of the peaks, to 59% to 73%, the height of the peaks can be reduced to suppress excessive flexibility and prevent the independent wave cable protective tube from bending too much. This improves the wire passing and heat dissipation properties of the independent wave cable protective tube. In addition, the accommodation cross-sectional area of ​​the electric wire or cable can be expanded to reduce the weight of the cable protective tube, which also leads to cost reduction. Here, by placing importance on the strength of the cable protection tube and setting the ratio of the difference in height between the peaks and valleys to the outer diameter of the tube to between 6% and 10%, it is possible to appropriately set the outer diameter and wall thickness of the peaks of the cable protection tube to achieve a high accommodation cross-sectional area ratio of between 59% and 73% compared to the conventional accommodation cross-sectional area ratio of between 50% and less than 59% (preferably between 50% and 58%), and it is even more preferable to set the accommodation cross-sectional area ratio to between 60% and 72%.

[0041] This also makes it possible to suppress excessive flexibility when bending the conduit to 5mR or 10mR, making it possible to correct the bending angle and to suppress the upper cable protection tube from pressing against the lower cable protection tube when multiple cable protection tubes are arranged at the conduit entrance, thereby improving workability when laying the cable protection tube.

[0042] Similarly, by forming groove-shaped recesses in the peaks to increase rigidity, the deflection rate as compressive strength measured by the method specified in the compressive strength test of JIS C 3653 Appendix 1 using an independent wave cable protection tube satisfies 3.5% or less, and the generated stress of the independent wave cable protection tube at a buried depth of 5m is 13.5MP or less, which satisfies 1 / 3 or less of the breaking strength of rigid polyvinyl chloride resin.

[0043] The second invention is a connection structure between an independent wave cable protection tube and a female joint member according to the first invention, wherein the female joint member has female joint structures symmetrically on both sides, and the female joint structure has an inner circumferential surface that is approximately parallel in a longitudinal cross section, or has a taper that gradually reduces in diameter from one end toward the longitudinal center of the female joint member, and the independent wave cable protection tube is cut at the groove-shaped recess provided in the center of the peak at any position of the independent wave cable protection tube, and an adhesive is applied to the peak near the cut end, and when the cut end of the independent wave cable protection tube is inserted into the female joint structure, the center of the peak of the cut end is pressed against the inner circumferential surface of the female joint structure while being inserted, thereby connecting the female joint member and the independent wave cable protection tube.

[0044] In this case, the joint member, the independent wave cable protection tube, and the joint member are bonded and fixed by an adhesive applied to the surface of the crest of the independent wave cable protection tube. Here, the inner peripheral surface of the female joint member is configured to gradually narrow slightly from one end toward the center in the longitudinal direction of the female joint member in order to reduce the insertion resistance when inserting the male joint structure, but after the crest of the independent wave cable protection tube comes into contact with the surface of the female joint member, the insertion resistance increases slightly, but at this time, there is an effect of increasing the adhesive pressure of the adhesive part.

[0045] According to the second invention, it is not necessary to form a protrusion or the like on the inner surface of the female joint member, and the female joint member and the cable protection tube can be connected by bonding to the inner wall of the tube. Here, a seal layer is formed by the adhesive between the peak of the cable protection tube and the inner peripheral surface of the female joint member, and this seal layer plays a role in providing watertightness. In addition, since the connection end is formed along the groove-shaped recess, the structure of the end of the cable protection tube is stable, and it can be stably connected to the female joint member. In addition, when performing an adhesive type joint in which a ring member is not placed in the groove-shaped recess of the female joint member and the peak, the adhesive is also applied to the groove-shaped recess, and the adhesive applied to the groove-shaped recess is supplied to the peak bonding surface behind it together with the adhesive applied directly, thereby becoming an additional supply source of adhesive, and therefore the formation of the groove-shaped recess ensures a more stable adhesive state. In this case, the joint member does not necessarily have a taper that reduces in diameter toward the center in the longitudinal direction in the longitudinal cross section as described above, and even if the inner circumferential surfaces are approximately parallel, the joint member is pulled out to the rear of the groove-shaped recess due to the shear force acting on the adhesive interface due to the movement of the inner circumferential surface of the female joint structure of the cable protection tube when the cable protection tube is inserted and the viscosity of the adhesive itself, thereby obtaining a similar effect.

[0046] The third invention is a connection structure between an independent wave cable protection tube and a female joint member according to the first invention, wherein the female joint member has female joint structures symmetrically on both sides, and the female joint structure has an inner circumferential surface that gradually narrows slightly from one end toward the longitudinal center of the female joint member in a longitudinal cross section, and when the male joint structure is inserted into the female joint structure, the rubber water-stopping member of the male joint structure formed near the cut end of the independent wave cable protection tube and the other small rubber water-stopping member are both pressed against the inner surface of the female joint structure, thereby connecting the female joint member and the male joint structure.

[0047] According to the third invention, there is no need to provide a protrusion on the inner pipe surface of the female coupling member, and the female coupling member and the cable protection tube can be connected by friction of the water-stopping member. Also, as described above, since the connection end is formed along the groove-shaped recess, the structure of the end of the cable protection tube is stable, and it can be stably connected to the female coupling member.

[0048] A fourth invention is a connection structure between an independent wave cable protection tube and a female joint member according to the first invention, wherein the female joint member has female joint structures symmetrically on both sides, The female joint structure has an inner circumferential surface in a longitudinal cross section that has a protrusion that protrudes radially toward the center from one end at a predetermined position toward the longitudinal center of the female joint member, and has a fitting portion that expands in diameter from the minimum inner diameter portion of the protrusion.The female joint structure is characterized in that, after pressing the first locking piece of the resin anti-slip ring of the male joint structure formed near the cut end of the independent wave cable protection tube and inserting the male joint structure into the female joint structure, the end of the first locking piece that expands in the diagonal direction of the elastically recovered anti-slip ring abuts against the fitting portion of the female joint structure, and the rubber water-stopping member arranged in at least one of the groove-shaped recesses of the peaks or the valleys is pressed against the inner circumferential surface of the female joint structure, thereby connecting the female joint member and the male joint structure.

[0049] According to the fourth aspect of the present invention, the female joint member and the cable protection tube can be connected by forming a protrusion on the inner surface of the female joint member and fitting it into the locking piece of the retaining ring. In addition, since the connection end is formed along the groove-shaped recess, the structure of the end of the cable protection tube is stable, and it can be stably connected to the female joint member.

[0050] The fifth invention is a method for cutting an independent-wave cable protection tube made of rigid polyvinyl chloride resin, the independent-wave cable protection tube has a circular cross section perpendicular to the tube axis direction, and has a wave shape in which peaks and valleys are repeated in the tube axis direction, the peaks are rectangular in the tube axis direction of the independent-wave cable protection tube and have a flat portion at the top, and a groove-shaped recess having a substantially U-shape is provided in the center of the flat portion of the peak, and the groove-shaped recess is provided continuously in the entire peak portion or in at least two or more peaks adjacent in the tube axis direction, and the independent-wave cable protection tube is cut at the groove-shaped recess provided in the center of the peak portion at any position of the independent-wave cable protection tube.

[0051] According to the fifth aspect of the present invention, when the independent wave cable protective tube is cut, the cutting can be performed using the groove-shaped recess as a guide. Therefore, the cutting can be performed stably and substantially perpendicularly to the tube axis direction at the peak portion. In this way, the female coupling member can be stably connected to another female coupling member.

[0052] The sixth invention is a method for connecting an independent wave cable protection tube made of a hard polyvinyl chloride resin to a female joint member, the female joint member having a female joint structure symmetrically on both sides, the independent wave cable protection tube having a circular cross section perpendicular to the tube axis direction and a corrugated shape in which peaks and valleys are repeated in the tube axis direction, the peaks are rectangular with a flat portion at the top with respect to the tube axis direction of the independent wave cable protection tube, and a substantially U-shaped groove-shaped recess is provided in the center of the flat portion of the peak, and the groove-shaped recess is provided continuously on all peaks of the peaks or on at least two or more peaks adjacent to each other in the tube axis direction, the independent wave cable protection tube is cut at the groove-shaped recess provided in the center of the peak at an arbitrary position of the independent wave cable protection tube, and the cut end of the independent wave cable protection tube is inserted into the female joint structure to connect the female joint member and the independent wave cable protection tube. This is a method for connecting an independent wave cable protection tube to a female joint member, the method being characterized in that:

[0053] The independent wave cable protection tube may be cut at a location where three or more consecutive groove-shaped recesses are provided, at the groove-shaped recesses of the mountain portions at both ends and at the groove-shaped recesses of the mountain portions at the middle portion.

[0054] The female joint structure has an inner circumferential surface that is approximately parallel in a longitudinal cross section, or has a taper that gradually reduces in diameter from one end toward the longitudinal center of the female joint member, and the independent wave cable protective tube has a slope portion that connects the valley portion and the crest portion between the valley portion and the crest portion with respect to a tube axis direction of the independent wave cable protective tube, and a length from the center of the slope portion that sandwiches the crest portion to the center is longer than a length from the center of the slope portion that sandwiches the valley portion, and and the sloped portions on both sides of the valley portion are formed in an approximately U-shape, or the valley portion has a straight portion that is shorter than the flat portion of the peak portion, and the valley portion and the sloped portions on both sides of the valley portion are formed in an inverted trapezoidal shape, and the female joint member and the independent wave cable protection tube may be connected by applying an adhesive to the peak portion near the cut end, inserting the cut end of the independent wave cable protection tube into the female joint structure, and inserting the female joint structure while pressing the inner surface of the female joint structure at the center of the peak portion of the cut end.

[0055] The female joint structure has an inner circumferential surface that gradually narrows slightly from one end toward the longitudinal center of the female joint member in a longitudinal cross section, and the independent wave cable protection tube is cut at the groove-shaped recess provided in the center of two or more consecutive peaks provided at any position, a rubber water-stopping member is attached to the valley portion adjacent to the cut peak portion, and another small rubber water-stopping member is further provided in the groove-shaped recess of the peak portion adjacent to the valley portion, a male joint structure is formed at the end of the independent wave cable protection tube, the male joint structure of the independent wave cable protection tube is inserted into the female joint structure, and both the rubber water-stopping member of the male joint structure and the other small rubber water-stopping member are pressed against the inner surface of the female joint structure, thereby connecting the female joint member and the male joint structure.

[0056] The female joint structure has an inner circumferential surface in a longitudinal cross section having a protrusion protruding from one end toward the radial center at a predetermined position toward the longitudinal center of the female joint member, and a fitting portion expanding in diameter from a minimum inner diameter portion of the protrusion, the independent wave cable protection tube has a pitch of the valley portion corresponding to a half pitch of a corrugated shape of 20 mm or more, the independent wave cable protection tube is cut at the groove-shaped recess provided in the center of the peak portion at an arbitrary position of the independent wave cable protection tube, and a ring-shaped or substantially C-shaped resin retaining ring is attached to the valley portion adjacent to the cut peak portion, the retaining ring has a first locking piece expanding in an oblique direction and a second locking piece parallel to the tube axial direction, the first locking piece and the second locking piece are arranged in a circumferential direction. a male joint structure having a structure extending from a base portion continuous in a direction perpendicular to the pipe, the male joint structure having a structure in which a water-stopping member made of rubber is provided in at least one of the groove-shaped recesses of the peaks adjacent to the valleys or the next valley portion on the inner side of the pipe adjacent to the valleys, and a male joint structure is formed at an end of the independent wave cable protection pipe, and after the male joint structure is inserted into the female joint structure, the end of the first locking piece of the anti-slip ring of the male joint structure, which expands in a diagonal direction after elastic recovery, abuts against the fitting portion of the female joint structure, and the water-stopping member arranged in at least one of the groove-shaped recesses of the peaks adjacent to the valleys, is pressed against an inner peripheral surface of the female joint structure, thereby connecting the female joint member and the male joint structure.

[0057] According to the sixth aspect of the present invention, the cutting position can be set at the center of two or more consecutive crests, making it easy to adjust the length of the cable protection tube. In addition, since the connection end is formed along the groove-shaped recess, the structure of the end of the cable protection tube is stable and it can be stably connected to the female joint member. In addition, the groove-shaped recess can be used as a cutting groove as well as a ring-shaped water-stopping member arrangement portion to form a male joint structure. This makes it possible to reduce the size of the male joint structure and to use it for a double water-stopping structure. Furthermore, if a groove-shaped recess is provided in the valley portion and then cut, it becomes an obstacle when passing the wire, but by forming a groove-shaped recess in the crest portion, it does not become an obstacle when passing the wire, and the cable surface is not damaged when passing the wire.

[0058] Furthermore, if the female joint structure has an inner circumferential surface that is approximately parallel in a longitudinal cross section, or has a taper that gradually reduces in diameter from one end toward the longitudinal center of the female joint member, there is no need to form a protrusion or the like on the inner pipe surface of the female joint member, and the female joint member and the cable protection tube can be connected by bonding to the inner pipe wall.

[0059] In addition, high water stopping performance can be ensured by pressing both the rubber water stopping member of the male joint structure of the independent wave cable protection tube and another small rubber water stopping member with the inner surface of the female joint structure.

[0060] Furthermore, by forming a protrusion on the inner tubular surface of the female joint member and fitting it into the locking piece of the retaining ring, the female joint member and the cable protection tube can be securely connected. Effect of the Invention

[0061] According to the present invention, it is possible to provide an independent-wave cable protection tube that can stably obtain a cut end shape that can be connected to a female joint structure, a connection structure between an independent-wave cable protection tube and a female joint member, a method for cutting an independent-wave cable protection tube, and a method for connecting an independent-wave cable protection tube and a female joint member. [Brief description of the drawings]

[0062] [Figure 1] 1A is a partial cross-sectional view of the independent wave cable protection tube 1, and FIG. 1B is an enlarged view of part A in FIG. [Diagram 2] 4(a) to 4(d) are diagrams showing the wave shapes of peaks 3 and valleys 5 of an independent wave cable protection tube. [Diagram 3] 1A is a diagram showing a process of cutting the independent-wave cable protective tube 1, and FIG. 1B is a diagram showing the independent-wave cable protective tube 1 after it has been cut. [Figure 4] 1A is a diagram showing a state before the independent wave cable protection tube 1 is inserted into a female joint member 15, and FIG. 1B is a diagram showing a connection structure 10 in which the independent wave cable protection tube 1 and the female joint member 15 are connected. [Diagram 5]1A is a diagram showing the state before the male joint structure 23 of the independent wave cable protection tube 1 is inserted into the female joint member 15a, and FIG. 1B is a diagram showing the connection structure 10a connecting the independent wave cable protection tube 1 and the female joint member 15a. [Figure 6] 1A is a diagram showing a state before inserting a male joint structure 23a of the independent-wave cable protection tube 1 into a female joint member 15a, FIG. 1B is an enlarged view of part D in FIG. 1A, and FIG. 1C is a diagram showing a connection structure 10b connecting the independent-wave cable protection tube 1 and a female joint member 15a. [Figure 7] 1A is a diagram showing a state before a conventional independent wave cable protection tube 100 is inserted into a female joint member 15a, and FIG. 1B is a diagram showing a state after the independent wave cable protection tube 100 is inserted into the female joint member 15a. [Figure 8] 1A is a partial cross-sectional view of the independent wave cable protection tube 1a, and FIG. 1B is an enlarged view of part H in FIG. [Figure 9] 1A is a diagram showing the state before the male joint structure 23b of the independent-wave cable protection tube 1a is inserted into the female joint member 15b, and FIG. 1B is a diagram showing the connection structure 10c connecting the independent-wave cable protection tube 1a and the female joint member 15b. [Figure 10] 1A is a diagram showing a state before a conventional independent wave cable protection tube 100 is inserted into a female joint member 15b, and FIG. 1B is a diagram showing a state after the independent wave cable protection tube 100 is inserted into the female joint member 15b. [Figure 11] 1A is a diagram showing a state before the male joint structure 23c of the independent-wave cable protection tube 1a is inserted into the female joint member 15b, FIG. 1B is an enlarged view of part I of FIG. 1A, and FIG. 1C is a diagram showing a connection structure 10d connecting the independent-wave cable protection tube 1a and the female joint member 15b. [Figure 12] 1A is a diagram showing a state before the male joint structure 23d of the independent-wave cable protection tube 1a is inserted into the female joint member 15b, FIG. 1B is an enlarged view of the J portion of FIG. 1A, and FIG. 1C is a diagram showing a connection structure 10e connecting the independent-wave cable protection tube 1a and the female joint member 15b. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0063] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1(a) is a front view of an independent wave cable protection tube 1, and the upper half is a cross-sectional view. Fig. 1(b) is an enlarged view of part A in Fig. 1(a). The independent wave cable protection tube 1 has a circular cross section perpendicular to the tube axis direction, is made of hard polyvinyl chloride resin, and is formed by, for example, extrusion blow molding. The outer surface of the independent wave cable protection tube 1 has a wave shape in which peaks 3 and valleys 5 are repeated in the tube axis direction.

[0064] The wave pitch of the rectangular wave formed by the peaks 3 and valleys 5 is, for example, 35 mm to 70 mm, and more preferably 40 mm to 60 mm. If the wave pitch is less than 35 mm, the number of slopes connecting the peaks 3 and valleys 5, which contribute most to flexibility, increases per given length, and the flexibility increases, which is undesirable because the flexibility becomes excessive. For this reason, it is preferable that the lower limit of the wave pitch is 35 mm. The upper limit of the wave pitch is 70 mm or less, because if the wave pitch becomes too large, the flexibility decreases and the pressure resistance of the tube decreases. Details of various shapes of the peaks 3 and valleys 5 will be described later. In this way, by setting the wave pitch of the rectangular wave to 35 mm or more and 70 mm or less, the length of the slopes 19 and the number of slopes 19 per given length of the independent wave cable protective tube 1 can be reduced, and excessive flexibility can be suppressed.

[0065] The outer diameter of the independent wave cable protective tube 1 is not particularly limited, but is, for example, 120φ to 300φ, and more preferably, the outer diameter is 150φ to 250φ. The thickness of the independent wave cable protective tube 1 is not particularly limited, and is set appropriately according to the outer diameter. However, the thickness of the independent wave cable protective tube 1 affects flexibility and strength. In particular, since the independent wave cable protective tube 1 is buried in the ground and used as a protective member, strength, especially pressure resistance, becomes an issue.

[0066] Therefore, when the outer diameter is between 120 mm and 300 mm, for example, the wall thickness is about 2 mm when the tube diameter is 120 mm, and the wall thickness can be about 3 mm when the tube diameter is 250 mm, or 3.5 mm when the tube diameter is 300 mm. Of course, the wall thickness increases as the diameter of the independent wave cable protective tube 1 increases. For example, when the tube diameter exceeds 180 mm, the wall thickness of the independent wave cable protective tube 1 can be appropriately set in the range of 2.5 mm to 3.5 mm.

[0067] The outer shape of the mountain portion 3 is substantially rectangular in the tube axis direction of the independent wave cable protective tube 1, and a flat portion 9 is formed at the top. That is, the top of the mountain portion 3 is formed in a straight line in the tube axis direction of the independent wave cable protective tube 1. In addition, a substantially U-shaped groove-shaped recess 7 is provided at the center of the flat portion 9 of the mountain portion 3 in the tube axis direction of the independent wave cable protective tube 1. The groove-shaped recess 7 is continuous in the circumferential direction. In the illustrated example, the groove-shaped recess 7 is formed for all the mountain portions 3, but the groove-shaped recess 7 may be formed for every predetermined number of mountain portions 3. In addition, it is desirable to provide the groove-shaped recess 7 periodically and continuously in at least two or more mountain portions 3 adjacent to each other in the tube axis direction. This is because, when the independent wave cable protective tube 1 is cut at one mountain portion 3 of two or more continuous mountain portions 3, a water-stopping member 17 (see, for example, FIG. 5(b)) described later can be arranged in the groove-shaped recess 7 of the remaining mountain portion 3. Furthermore, it is preferable that the groove-shaped recess 7 is provided continuously in at least three or more adjacent peaks 3 in the tube axial direction. This is because by cutting the independent wave cable protective tube 1 at the intermediate peak 3 (the middle peak in FIG. 2(a)) excluding the peaks 3 at both ends among the three or more peaks 3 (see FIG. 2(a) for example), the independent wave cable protective tube 1 having the peaks 3 (each peak on both sides in FIG. 2(a)) with the groove-shaped recess 7 formed therein can be formed at the ends of the independent wave cable protective tube 1 on both sides after cutting, and in each independent wave cable protective tube 1, a water-stopping member to be described later can be disposed in the groove-shaped recess 7, and the independent wave cable protective tube 1 can be effectively used without being wasted, which is convenient.

[0068] The depth of the groove-shaped recess 7 provided in the center of the peak 3 is not particularly limited, but the depth of the groove-shaped recess 7 is equal to or less than half the difference in height between the peak 3 and the valley 5 of the independent wave cable protective tube 1. For example, the depth of the groove-shaped recess 7 is about 5 mm, and the width (length in the tube axis direction) is about 4 mm. The depth of the groove-shaped recess 7 may be determined according to the outer diameter of the independent wave cable protective tube 1 so as to be 5 mm or more, more preferably 6 mm or more. The width of the groove-shaped recess 7 can be widened to about 6 mm when the wave pitch of the cable protective tube is wide. In this way, the shape, width, and depth of the groove-like recesses 7 in the present invention do not need to be fixed to be the same in relation to adjacent recesses or non-adjacent recesses, and can be different depending on the application.

[0069] As described above, the independent wave cable protective tube 1 is made of hard polyvinyl chloride resin, and the yield stress of the hard polyvinyl chloride resin constituting the independent wave cable protective tube 1 is desirably 40.5 MPa or more. By doing so, it is possible to ensure sufficient strength, for example, when bending is applied or when buried in the ground.

[0070] For example, it is desirable that the independent wave cable protective tube 1 has flexibility that allows it to be bent without problems in a 10mR bend test and a 5mR bend test. Furthermore, it is desirable that the deflection rate as compressive strength measured by the method specified in the compressive strength test of JIS C 3653 Appendix 1 using the independent wave cable protective tube 1 is 3.5% or less. It is also desirable that the stress generated by the independent wave cable protective tube at a buried depth of 5m is 13.5MPa or less, which is 1 / 3 or less of the breaking strength of the rigid polyvinyl chloride resin.

[0071] Here, the rectangular independent wave cable protection tube used in the present invention is formed by molding a cylindrical blank tube extruded from an extruder at a predetermined temperature using a plurality of opposing split dies arranged on an endless track, using dies of the shapes described in each embodiment described later.

[0072] Next, various types of wave shapes will be described in detail. Figures 2(a) to 2(d) are diagrams showing various types of wave shapes (shapes of peaks 3 and valleys 5). In each diagram, dotted line G is the center line in the height direction between peaks 3 and valleys 5 (the center line between the outer surface of peaks 3 and the inner surface of valleys 5). The left-right direction in each diagram is the tube axial direction of the independent wave cable protective tube.

[0073] In the example shown in Fig. 2(a), a slope 19 connecting the valley 5 and the peak 3 is formed between the valley 5 and the peak 3 in the tube axial direction of the independent wave cable protective tube, and the valley 5 and the slopes 19 on both sides of the valley 5 are formed in an approximately U-shape. Also, the length from center to center of the slopes 19 sandwiching the peak 3 (L in the figure) is longer than the length from center to center of the slopes 19 sandwiching the valley 5 (M in the figure). The wave shape of the independent wave cable protective tube 1 described above has such an approximately U-shaped valley 5.

[0074] Fig. 2(b) is substantially the same as Fig. 2(a), but has a different shape of valley portion 5. In the example shown in Fig. 2(b), like Fig. 2(a), a slope 19 connecting valley portion 5 and peak portion 3 is formed between valley portion 5 and peak portion 3 with respect to the tube axial direction of the independent wave cable protective tube, and the length from center to center of slope portion 19 sandwiching peak portion 3 (L in the figure) is longer than the length from center to center of slope portion 19 sandwiching valley portion 5 (M in the figure).

[0075] 2(b) is different from FIG. 2(a) in that in the cross section in the tube axis direction, valley portion 5 has a straight portion (the length of the straight portion of the inner surface of valley portion 5, F in the figure), and the length of straight portion 21 of valley portion 5 is shorter than the length of flat portion 9 of peak portion 3. In other words, it is different from FIG. 2(a) in that valley portion 5 and slope portions 19 on both sides of valley portion 5 are formed into an inverted trapezoid shape.

[0076] Fig. 2(c) is substantially the same as Fig. 2(b), but differs in the length of the valley portion 5 relative to the peak portion 3. In the example shown in Fig. 2(c), as in Fig. 2(b), a slope portion 19 connecting the valley portion 5 and the peak portion 3 is formed between the valley portion 5 and the peak portion 3 with respect to the tube axial direction of the independent wave cable protective tube, and a linear portion 21 is formed in the valley portion 5, so that the valley portion 5 and the slope portions 19 on both sides of the valley portion 5 are formed into an inverted trapezoidal shape.

[0077] 2(c), the length of the flat portion 9 of the peak 3 and the length of the straight portion 21 of the valley 5 are approximately equal in the cross section in the tube axis direction. That is, the peak 3 and the valley 5 are formed in straight lines of approximately the same length in the tube axis direction (E and F in the figure), and the wave shape in which the peak 3 and the valley 5 are connected by the slope 19 becomes an approximately trapezoidal rectangular independent wave shape that is inverted symmetrically with respect to the center line G that passes through the slope 19.

[0078] In addition, it is preferable that the pitch of the valley portion 5 of the independent wave cable protection tube, which corresponds to half the pitch of the corrugated shape, is 20 mm or more (i.e., the wave pitch of the corrugated shape is 40 mm or more).By doing so, it is possible to form a linear portion 21 of sufficient length in the valley portion 5, which makes it easy to place and hold a retaining ring in the valley portion 5 when forming a male joint structure described later.

[0079] Also, it is preferable that the ratio of the difference in height between the peaks 3 and the valleys 5 to the outer diameter of the pipe at the peaks 3 is 6% or more and 10% or less. Also, it is preferable that the accommodation cross-sectional area ratio is 59% or more and 73% or less. Here, the accommodation cross-sectional area ratio is the ratio of the circular cross-sectional area of ​​the inner diameter of the pipe at the valleys 5 (the circular cross-sectional area of ​​the circle formed by the inner surface of the pipe in a cross section perpendicular to the pipe axis direction at the valleys 5) to the circular cross-sectional area of ​​the outer diameter of the pipe at the peaks 3 (the circular cross-sectional area of ​​the circle formed by the outer surface of the pipe in a cross section perpendicular to the pipe axis direction at the peaks 3). In this way, the accommodation cross-sectional area ratio can be increased from the conventional accommodation cross-sectional area ratio of 50% or more and 58% or less to 59% or more and 73% or less, thereby improving wireability and heat dissipation. Here, the outer diameter of the cable protection tube is in the range of 120 mm or more and 300 mm or less, and the tube wall thickness is in the range of 2.0 mm or more and 3.5 mm or less (more preferably 2.5 mm or more and 3.0 mm or less), and each can be appropriately set taking into consideration the balance between pressure resistance and flexibility control. In this case, the accommodation cross-sectional area ratio can be written and defined as in the following formula (1). Accommodated cross-sectional area ratio = (Circular cross-sectional area of ​​the pipe inner diameter at valley portion 5) / (Circular cross-sectional area of ​​the outer diameter of the pipe at the crest 3) = {(Outer diameter of pipe at valley portion 5) - 2 × (wall thickness of pipe)} 2 / (Outer diameter of pipe at peak 3) 2 (1) Although the cross-sectional area ratio is defined as being calculated based on the outer diameter of the tube at the peak, the cross-sectional area can also be calculated based on the entire space of the tube including the space inside the peak. In this case, the space of the entire tube is based not on the outer diameter of the peak but on the space obtained by subtracting twice the wall thickness from the peak, so the space created by the entire tube becomes smaller by that amount, and the cross-sectional area usually increases by 3 to 4%.

[0080] In this way, the heights of the peaks 3 and valleys 5 are appropriately set. For example, in the example shown in Fig. 2(d), the shape of the peaks 3 and valleys 5 is similar to that of the example shown in Fig. 2(c), but the difference in height between the peaks 3 and valleys 5 is small. In this way, the heights of the peaks 3 and valleys 5 can be set low in consideration of the accommodation cross-sectional area rate, flexibility, etc.

[0081] In addition, the angle connecting the peak portion 3 and the slope portion 19 and the angle connecting the valley portion 5 and the slope portion 19 can be 90° to 120°. For example, compared with the case where the angle of the slope portion 19 is 120° to 150°, it is preferable that the slope angle is 90° to 120° because the pressure resistance of the independent wave cable protective tube is stable. Therefore, the slope portion 19 is usually set in the range of 90° to 120°, but the slope angle is more preferably 95° to 110°. Note that even if the slope angle is 90°, it is possible to set the slope angle to 90° because there is no problem of mold removal due to the setting of the corner R of the slope portion and thermal shrinkage after molding.

[0082] It is preferable that the R (fillet shape) connecting the valley portion 5 and the slope portion 19 is small. This is because as the R increases, the length of the straight portion of the valley portion 5 decreases. For this reason, the R connecting the valley portion 5 and the slope portion 19 is preferably 1.5 mm or more and 4 mm or less, and more preferably 2 mm or more and 3 mm or less. Here, when the slope angle of the slope portion is close to 90°, it is preferable that the R connecting the slope portion and the peak portion or the valley portion is large, and in particular, when considering the release of the product from the mold, it is preferable that the R connecting the slope portion on the peak portion side is large. Therefore, the R on the peak portion side does not need to be the same as the R on the valley portion side.

[0083] Next, a method for cutting the independent wave cable protective tube 1 will be described. As described above, the wave shape of the independent wave cable protective tube 1 is formed into a substantially U-shape by the valley portion 5 and the slope portion 19, as shown in FIG. 2(a). The independent wave cable protective tube 1 is long, and is used after being cut to a desired length. FIG. 3(a) is a diagram showing a process for cutting the independent wave cable protective tube 1 at a predetermined position. When cutting the independent wave cable protective tube 1, a blade 11 is placed against a groove-shaped recess 7 provided in a peak portion 3 at an arbitrary position of the independent wave cable protective tube 1, and the cutting can be performed by using the groove-shaped recess 7 as a guide.

[0084] 3(b) is a diagram showing a state in which the independent wave cable protective tube 1 has been cut. By cutting along the groove-shaped recess 7, the cut end does not become oblique to the tube axial direction, and the cut can be performed perpendicular to the tube axial direction. In this way, the independent wave cable protective tube 1 can be cut at the groove-shaped recess 7 provided in the center of the peak portion 3 at any position of the independent wave cable protective tube 1.

[0085] (Connection structure by bonding female joint member and independent wave cable protection tube) Next, a connection structure and a connection method between the female joint member and the independent wave cable protection tube will be described. The female joint member and the independent wave cable protection tube can be connected by inserting the cut end of the independent wave cable protection tube 1 after cutting into another female joint member. Fig. 4(a) is a cross-sectional view showing a state before inserting the cut end 13 of the independent wave cable protection tube 1 into the female joint member 15. The female joint member 15 is substantially cylindrical and has female joint structures 16 symmetrically on both sides.

[0086] In the illustrated example, the female joint structure 16 of the female joint member 15 has a taper in which the inner circumferential surface gradually narrows slightly from one end toward the center of the female joint member 15 in the longitudinal cross section, but the inner circumferential surface of the female joint structure 16 may be approximately parallel in the longitudinal cross section. The inner diameter of the opening of the female joint member 15 is larger than the maximum outer diameter of the independent wave cable protection tube 1, and the inner diameter of the narrowed portion near the center of the female joint member 15 is smaller than the maximum outer diameter of the independent wave cable protection tube 1. The female joint member 15 and the independent wave cable protection tube 1 can be connected by applying an adhesive to the outer surface of the peak portion 3 near the cut end 13 of the independent wave cable protection tube 1 and inserting the cut end 13 of the independent wave cable protection tube 1 from the end of the female joint member 15 (in the direction of the arrow B in the figure).

[0087] 4(b) is a diagram showing a connection structure 10 between a female joint member 15 and an independent wave cable protection tube 1. When the cut end portion 13 of the independent wave cable protection tube 1 is inserted into the female joint structure 16, the cut end portion 13 and the center of the crest portion 3 in its vicinity are inserted while being pressed against the inner peripheral surface of the female joint structure 16, thereby connecting the female joint member 15 and the independent wave cable protection tube 1. Furthermore, by inserting another independent wave cable protection tube 1 into the other end side (left side in the figure) of the female joint member 15 and connecting it in the same manner, the independent wave cable protection tubes 1 can be connected to each other. Furthermore, when applying adhesive to the peaks 3 of the independent wave cable protective tube 1 to form an adhesive layer, the adhesive is also applied to the groove-shaped recesses 7 adjacent to the cut end, and the adhesive applied to the groove-shaped recesses 7 is supplied to the surface of the peaks 3 by the tension due to the viscosity of the adhesive itself and the shear force due to the movement of the cable protective tube, so that sufficient adhesive is supplied to the bonding area, making the bonding between the female joint member 15 and the peaks of the independent wave cable protective tube 1 more stable and strong. In addition, in the case of an adhesive type joint, it goes without saying that the adhesive layer also serves as a sealing layer for stopping water.

[0088] (Connection structure between female joint member and independent wave cable protection tube using waterproof member) Next, another connection structure and connection method using the independent wave cable protection tube 1 will be described. FIG. 5(a) is a diagram showing a state before the male joint structure 23 formed near the cut end portion 13 of the independent wave cable protection tube 1 is inserted into the female joint member 15a. The female joint member 15a is substantially cylindrical like the female joint member 15. The female joint structures 16a are formed symmetrically on both sides of the female joint member 15. In the illustrated example, the female joint structure 16a has an inner circumferential surface that is substantially parallel in a longitudinal cross section. That is, the female joint structure 16a has an inner diameter that is substantially constant in the longitudinal direction, but the female joint structure 16 may have an inner circumferential surface that is gradually and slightly reduced in diameter from one end toward the longitudinal center of the female joint member 15 in a longitudinal cross section.

[0089] As described above, the independent wave cable protection pipe 1 is cut at the groove-shaped recess 7 provided in the center of the peak 3 at any position. A rubber annular water-stopping member 17 is attached to the valley 5 adjacent to the cut peak 3. In this manner, a male joint structure 23 is formed at the end of the independent wave cable protection pipe 1.

[0090] The male joint structure 23 formed near the cut end 13 of the independent wave cable protection tube 1 can be inserted from the end of the female joint member 15 (in the direction of arrow C in the figure) to connect the female joint member 15a and the independent wave cable protection tube 1.

[0091] 5(b) is a diagram showing a connection structure 10a between a female joint member 15a and an independent wave cable protection tube 1. The maximum outer diameter of the attached water stop member 17 is larger than the maximum diameter of the crest portion 3 of the independent wave cable protection tube 1. Therefore, when the male joint structure 23 is inserted into the female joint structure 16a, the rubber water stop member 17 of the male joint structure 23 formed in the vicinity of the cut end portion of the independent wave cable protection tube 1 is pressed by the inner surface of the female joint structure 16a, and the female joint member 15a and the male joint structure 23 are connected.

[0092] In the connection structure 10a, the independent wave cable protection tube 1 is connected using the female joint member 15a whose inner surface is approximately parallel to the tube axis direction, but the independent wave cable protection tube 1 having the male joint structure 23 may be connected to the female joint member 15 having the joint taper on the inner surface described above. In this case, the water stop member 17 is pressed by the inner surface of the female joint structure 16, so that the female joint member 15 and the male joint structure 23 are connected.

[0093] (A connection structure with double waterproofing between the female joint material and the independent wave cable protection tube, using a male joint structure with a waterproofing material) Next, a description will be given of still another connection structure and connection method using the independent wave cable protection tube 1. Fig. 6(a) is a diagram showing a state before a male joint structure 23a formed in the vicinity of the cut end portion 13 of the independent wave cable protection tube 1 is inserted into a female joint member 15a, and Fig. 6(b) is an enlarged view of part D in Fig. 6(a).

[0094] As described above, the independent wave cable protective tube 1 is cut at the groove-shaped recess 7 provided at the center of the crest 3 that is provided in a continuous manner with two or more crests at any position. The independent wave cable protective tube 1 is cut so that the groove-shaped recess 7 remains in the crest 3 at the end (the crest 3 next to the cut crest 3) after cutting. A rubber water-stopping member 17 is attached to the valley 5 adjacent to the cut crest 3. In addition to this water-stopping member 17, another rubber water-stopping member 17a smaller than the water-stopping member 17 is provided in the groove-shaped recess 7 of the crest 3 adjacent to the valley 5. In this way, a male joint structure 23a is formed at the end of the independent wave cable protective tube 1.

[0095] 6(c) is a diagram showing a connection structure 10b between the female joint member 15a and the independent wave cable protection tube 1. When the male joint structure 23a is inserted into the female joint structure 16a, the rubber water-stopping member 17 of the male joint structure 23a formed near the cut end of the independent wave cable protection tube 1 and another small rubber water-stopping member 17a are both pressed by the inner surface of the female joint structure 16a, thereby connecting the female joint member 15a and the male joint structure 23a. As described above, a connection structure that performs double water-stopping with the water-stopping member 17 and the water-stopping member 17a can be obtained.

[0096] As described above, according to the embodiment using the independent wave cable protection tube 1, the groove-shaped recess 7 is provided in the peak portion 3 and can function as a guide when cutting, so that the independent wave cable protection tube 1 can be cut approximately perpendicularly to the tube axial direction when cutting. Therefore, the cut end portion 13 does not become inclined, and the shape of the male joint structure formed in the vicinity of the cut end portion 13 can be stabilized. Here, the groove-shaped recess has an effect of stabilizing the cut end portion 13 and an effect of providing an arrangement portion for a small water stop member 17a.

[0097] (Comparison of the shapes of the cut ends of the independent wave cable protection tubes with and without the groove-shaped recesses and the structures when these independent wave cable protection tubes are connected to the female joint structures) For example, Fig. 7(a) is a diagram showing a state before connection between an independent wave cable protection tube 100 having no groove-shaped recess 7 and a female joint member 15a. The independent wave cable protection tube 100 has a shape substantially similar to that of the independent wave cable protection tube 1, but a groove-shaped recess 7 is not formed at the top of the peak portion 3. For this reason, as shown in the figure, when the independent wave cable protection tube 100 is cut at the peak portion 3, there is a risk that the cut end portion 13a will be formed at an angle to the tube axial direction, and there are cases in which an actually oblique cut surface is formed.

[0098] In this case, for example, as in Fig. 5, when the water-stopping member 17 is arranged in the valley portion 5 and the cut end portion 13a is inserted into the female joint structure 16a as in the connection structure 110 shown in Fig. 7(b), the water-stopping member 17 is pressed by the inner surface of the female joint structure 16a, and the female joint member 15a and the independent wave cable protective tube 100 are connected by friction. However, since the cut end portion 13a is inclined, the water-stopping member 17 is not securely held by the inclined surface portions 19 on both sides of the valley portion 5, and when a pulling force is applied to the independent wave cable protective tube 100, the water-stopping member 17 may be displaced, or the water-stopping member 17 may come off the independent wave cable protective tube 100 due to deformation of the end portion of the independent wave cable protective tube 100.

[0099] In contrast, in the independent wave cable protection tube 1, the cut end portion 13 is formed perpendicular to the tube axial direction, so the water-stopping member 17 is stably disposed regardless of the circumferential position. Therefore, there are no problems as described above, and it is possible to stably ensure the strength of the male joint structure.

[0100] In addition, since the peak portion 3 is a portion with a large outer diameter, the cutting work becomes difficult and stable cutting is difficult, especially when the diameter of the independent wave cable protection tube 1 becomes large. However, since the groove-shaped recess 7 is provided, even a large-diameter independent wave cable protection tube 1 that is difficult to cut becomes easy to cut.

[0101] In addition, the cross section of the independent wave cable protective tube 1 is reinforced by the groove-shaped recesses 7 provided in the peaks 3, so that the compressive strength is increased and the flexibility can also be improved. Therefore, even if the difference in height between the peaks 3 and the valleys 5 is reduced within a predetermined range, the accommodation cross-sectional area rate of the independent wave cable protective tube 1 is increased, and at the same time, the heat dissipation is improved, it is possible to obtain the independent wave cable protective tube 1 with sufficient compressive strength and flexibility.

[0102] (Cutting guide and length adjustment effect when groove-like recesses are provided at regular intervals in the center of the peak) In addition, since cutting can be performed at any peak 3, the length of the independent wave cable protective tube 1 can be easily adjusted. As described above, it is not necessary to provide the groove-shaped recesses 7 in all peaks 3. In this case, the groove-shaped recesses 7 may be provided at a predetermined interval between peaks 3. For example, the groove-shaped recesses 7 may be provided in the peaks 3 at intervals of 4 pitches or less (intervals of 5 peaks). Even in this case, if the pitch of the peaks 3 is set to 35 mm to 70 mm, the groove-shaped recesses 7 are formed at intervals of 175 mm to 350 mm, which can be used as a guide when cutting. In this way, the groove-shaped recesses 7 are provided in the peaks 3 in all peaks 3 or at any position, continuously with at least two or more peaks adjacent to each other in the tube axis direction.

[0103] There is also a method of providing a groove-shaped recess 7 in the valley portion 5 and cutting the independent wave cable protection tube at the valley portion 5, but when the valley portion 5 is cut, the end of the cut valley portion 5 protrudes in the tube axis direction, which may cause an obstacle when inserting or passing the cable, which is problematic. In addition, a convex portion is formed on the inner side corresponding to the groove-shaped recess of the valley portion 5, so the minimum inner diameter of the independent wave cable protection tube becomes small. In contrast, by providing the groove-shaped recess 7 in the peak portion 3, it is possible to function as an installation portion for the water stop member 17a without affecting the wire passing property. In this way, the groove-shaped recess 7 can be used as either a guide groove for cutting the independent wave cable protection tube 1 or an installation portion for the ring-shaped water stop member of the male joint structure.

[0104] (Male joint structure using a retaining ring formed on the cut end) Next, an embodiment using an independent wave cable protection tube having another wave shape will be described. Fig. 8(a) is a partial cross-sectional view (upper half is a cross-sectional view) showing a male joint structure 23b using the independent wave cable protection tube 1a, and Fig. 8(b) is an enlarged view of part H in Fig. 8(a). In the following description, the same reference numerals as in Figs. 1 to 7 are used for configurations that have the same effects as the independent wave cable protection tube 1 described above, and duplicated descriptions will be omitted.

[0105] The independent wave cable protective tube 1a has a different wave shape from the independent wave cable protective tube 1, and has a form corresponding to Fig. 2(c) described above. That is, in the tube axial direction of the independent wave cable protective tube 1a, a slope portion 19 is formed between the peak portion 3 and the valley portion 5, the peak portion 3 and the valley portion 5 are formed in a straight line of approximately the same length in the tube axial direction, and the wave shape formed by the peak portion 3, the valley portion 5 and the slope portion 19 is an approximately trapezoidal rectangular independent wave shape that is inverted symmetrically with respect to the center line passing through the slope portion 19.

[0106] As described above, the independent wave cable protective tube 1a is cut at the groove-shaped recess 7 provided in the center of the peak 3 at an arbitrary position. A resin retaining ring 25 is attached to the valley 5 adjacent to the cut peak 3. The retaining ring 25 is annular or substantially C-shaped. The retaining ring 25 has a first locking piece 27a that expands in an oblique direction and a second locking piece 27b that is parallel to the tube axis direction, and the first locking piece 27a and the second locking piece 27b have a structure that extends from a base portion 29 that is continuous in the circumferential direction. The first locking piece 27a and the second locking piece 27b are alternately formed at a predetermined interval in the circumferential direction.

[0107] As described above, the independent wave cable protective tube 1a has a pitch of the valley portion 5, which corresponds to half the pitch of the corrugated shape, of 20 mm or more (i.e., the wave pitch of the corrugated shape is 40 mm or more). In this way, the retaining ring 25 can be stably attached to the valley portion 5. Here, since the retaining ring is attached to the valley portion, if the dimension of the valley portion is narrow, the inclination angle of the locking claw of the ring becomes steep, the stress applied to the locking claw becomes large, the locking claw becomes unstable, and there is a risk of the locking claw being damaged. Therefore, when using a retaining ring, it is desirable to have a large wave pitch.

[0108] A rubber water-stopping member 17 is provided in the next valley portion 5 on the inner side of the pipe adjacent to the valley portion 5 to which the retaining ring 25 is attached. Note that the maximum outer diameter of the first locking piece 27a of the retaining ring 25 and the maximum outer diameter of the attached water-stopping member 17 are larger than the maximum outer diameter of the peak portion 3 of the independent wave cable protection tube 1a. In this manner, a male joint structure 23b is formed at the end portion of the independent wave cable protection tube 1a.

[0109] (Connection structure between a male joint structure using a retaining ring for an independent wave cable protection tube and a female joint structure of a female joint member) Next, a connection structure and a connection method between the independent wave cable protection tube 1a and the female joint member will be described. Fig. 9(a) is a diagram showing a state before the male joint structure 23b formed near the cut end portion 13 of the independent wave cable protection tube 1a is inserted into the female joint member 15b.

[0110] The female coupling member 15b is substantially cylindrical, and female coupling structures 16b are formed symmetrically on both sides of the female coupling member 15b. In a longitudinal cross section, the female coupling structure 16b has a protrusion 31 whose inner circumferential surface protrudes toward the center in the radial direction at a predetermined position from one end of the female coupling member 15b toward the center in the longitudinal direction of the female coupling member 15b, and a fitting portion 33 that expands in diameter from the minimum inner diameter portion of the protrusion 31 is provided further inside the protrusion 31.

[0111] 9(b) is a diagram showing a connection structure 10c between a female joint member 15b and an independent wave cable protection tube 1a. As described above, the maximum outer diameter of the retaining ring 25 and the water stop member 17 of the male joint structure 23b is larger than the maximum diameter of the crest portion 3 of the independent wave cable protection tube 1a. In addition, the inner diameter of the protrusion portion 31 is smaller than the maximum outer diameter of the retaining ring 25 and the water stop member 17.

[0112] Therefore, when the male joint structure 23b is inserted into the female joint structure 16b, the first locking piece 27a of the retaining ring 25 arranged near the cut end of the independent wave cable protection tube 1a is pressed by the inner surface of the protrusion 31 of the female joint structure 16b and is reduced in diameter by elastic deformation. When the first locking piece 27a is pushed into the fitting portion 33 in a pressed state, it elastically recovers and expands in an oblique direction, so that the end of the first locking piece 27a abuts and fits into the fitting portion 33 of the female joint structure 16b. At this time, the outer surface of the water stop member 17 arranged in the valley portion 5 is pressed by the inner peripheral surface of the female joint structure 16b, thereby connecting the female joint member 15b and the male joint structure 23b.

[0113] As a result, the female joint member 15b and the male joint structure 23b having a structure for preventing dislodging by mechanical contact are connected. In addition, by inserting another independent wave cable protective tube 1a (male joint structure 23b) into the other end side (left side in the figure) of the female joint member 15b and connecting it in the same manner, it is also possible to connect the independent wave cable protective tubes 1a to each other.

[0114] In this case, since the female joint member 15b and the male joint structure 23b are engaged not by the frictional force between the water-stopping member 17 and the female joint structure 16a as described above but by the abutment of the first locking piece and the fitting portion 33, it is not necessary to lengthen the female joint member to ensure the amount of friction, and the female joint structure 16b can be shortened. Also, by using the retaining ring 25, the female joint structure can be made smaller in size compared to an abutment structure using rubber instead of the retaining ring 25.

[0115] In the present embodiment using the independent wave cable protection tube 1a, it is possible to obtain the same effect as in the case of using the independent wave cable protection tube 1. That is, since the cut end portion 13 of the independent wave cable protection tube 1a is formed substantially perpendicular to the tube axial direction, it is possible to obtain a stable shape of the male joint structure 23b.

[0116] (Connection structure between a male joint structure using a retaining ring for an independent wave cable protection tube having no groove-shaped recess and a female joint structure of a female joint member) For example, Fig. 10(a) is a diagram showing a state before the independent wave cable protection tube 100 without the groove-shaped recess 7 and the female joint member 15b are connected. As described above, the independent wave cable protection tube 100 has a shape substantially similar to that of the independent wave cable protection tube 1, but the groove-shaped recess 7 is not formed at the top of the peak portion 3. For this reason, as shown in the figure, when the independent wave cable protection tube 100 is cut at the peak portion 3, the cut end portion 13a may be formed obliquely with respect to the tube axial direction.

[0117] In this case, for example, as in Fig. 9, when the retaining ring 25 and the water-stopping member 17 are arranged in the valley portion 5, and the cut end portion 13a is inserted into the female joint structure 16b as in the connection structure 110a shown in Fig. 10(b), the first locking piece 27a of the retaining ring 25 fits into the fitting portion 33. However, since the cut end portion 13a is inclined, the retaining ring 25 is not securely held by the inclined surfaces on both sides of the valley portion 5, and when a pulling force is applied to the independent wave cable protective tube 100, problems such as the retaining ring 25 coming off the independent wave cable protective tube 100 due to deformation of the end portion of the independent wave cable protective tube 100 may occur.

[0118] In contrast, in the independent wave cable protection tube 1a, the cut end portion 13 is formed perpendicular to the tube axial direction, so that the retaining ring 25 can be reliably held in the valley portion 5 regardless of the circumferential position. Therefore, there are no problems as described above, and it is possible to stably ensure the strength of the male joint structure.

[0119] (Connection structure between a male joint structure of an independent wave cable protection tube using a retaining ring and a small water-stopping member and a female joint structure of a female joint member) Next, another connection structure and connection method using the independent wave cable protection tube 1a will be described. Fig. 11(a) is a diagram showing a state before inserting a male joint structure 23c formed near the cut end portion 13 of the independent wave cable protection tube 1a into a female joint member 15b, and Fig. 11(b) is an enlarged view of part I in Fig. 11(a).

[0120] As described above, the independent wave cable protective tube 1a is cut at the groove-shaped recess 7 provided in the center of the peak 3 at an arbitrary position. A retaining ring 25 is attached to the valley 5 adjacent to the cut peak 3. A small rubber annular water-stopping member 17a is provided in the groove-shaped recess 7 of the peak 3 adjacent to the valley 5. In this way, a male joint structure 23c is formed at the end of the independent wave cable protective tube 1a.

[0121] 11(c) is a diagram showing a connection structure 10d between the female joint member 15b and the independent wave cable protection tube 1a. As described above, when the male joint structure 23c is inserted into the female joint structure 16b, the end of the first locking piece 27a abuts against and fits into the fitting portion 33 of the female joint structure 16b. In addition, the outer surface of the water-stopping member 17a is pressed against the inner surface of the protrusion 31. In this way, the female joint member 15b and the male joint structure 23b are connected.

[0122] In this way, by attaching an anti-slip ring 25 to the valley portion 5 near the cut end 13 and providing a rubber water-stopping member 17a or water-stopping member 17 in at least one of the groove-shaped recess 7 of the peak portion 3 adjacent to the valley portion 5 or the next valley portion 5 on the inner side of the tube adjacent to the valley portion 5, a male joint structure 23b or male joint structure 23c can be formed at the end of the independent wave cable protection tube 1a.

[0123] Furthermore, when connecting the female joint member 15b and the independent wave cable protection tube 1a, the first locking piece 27a of the anti-slip ring 25 is fitted into the fitting portion 33 of the female joint structure 16b, and the rubber water-stopping members 17, 17a arranged in at least one of the groove-shaped recesses 7 of the valley portion 5 or the peak portion 3 are pressed against the inner surface of the female joint structure 16b, thereby connecting the female joint member 15b and the male joint structure 23c.

[0124] (A double waterproof connection structure consisting of a male joint structure of an independent wave cable protection tube using a retaining ring, a small waterproof member, and a waterproof member, and a female joint structure of a female joint member) In addition, both of the water-stopping members 17 and 17a may be used. Fig. 12(a) is a diagram showing a state before the male joint structure 23d formed in the vicinity of the cut end portion 13 of the independent wave cable protection tube 1a is inserted into the female joint member 15b, and Fig. 12(b) is an enlarged view of part J in Fig. 12(a).

[0125] As described above, the retaining ring 25 is attached to the valley portion 5 adjacent to the cut peak portion 3 of the independent wave cable protective tube 1a. Also, the small rubber water stop member 17a is attached to the groove-shaped recess 7 of the peak portion 3 adjacent to the valley portion 5, and the rubber water stop member 17 is attached to the valley portion 5 on the further back side. In this case, a double water stop structure of the small water stop member 17a and the water stop member 17 can be formed. In this way, a male joint structure 23d is formed at the end portion of the independent wave cable protective tube 1a.

[0126] Fig. 12(c) is a diagram showing a connection structure 10e between the female joint member 15b and the independent wave cable protection tube 1a. When the male joint structure 23d is inserted into the female joint structure 16b, the end of the first locking piece 27a of the retaining ring 25 abuts and fits into the fitting portion 33 of the female joint structure 16b as described above. In addition, the outer surfaces of the water-stopping members 17, 17a are pressed against the inner surface of the female joint structure 16b. In this way, the female joint member 15b and the male joint structure 23d are connected.

[0127] As described above, according to the embodiment using the independent wave cable protection tube 1a, the first locking piece 27a of the anti-slip ring 25 is fitted into the fitting portion 33 of the female joint structure 16b, thereby obtaining a stronger connection strength.

[0128] The female joint member connected to the independent wave cable protection tube 1a may have other configurations. For example, the female joint structure may have an inner circumferential surface in a longitudinal cross section that has an inclined surface portion that gradually decreases in diameter from one end toward the longitudinal center of the female joint member, and a fitting portion that expands in diameter from the minimum inner diameter portion of the inclined surface portion.

[0129] In this case, an inclined surface may be formed on the inner surface of a protrusion protruding toward the center in the radial direction at a predetermined position of the female joint member. In this case, the first locking piece 27a of the resin retaining ring 25 of the male joint structure formed near the cut end 13 of the independent wave cable protection tube 1a is pressed by the inclined surface of the female joint member, and the male joint structure is inserted into the female joint structure. After that, by further pushing the male joint structure, the end of the first locking piece 27a of the elastically recovered retaining ring 25, which expands in the diagonal direction, comes into contact with the fitting portion 33 of the female joint structure and is fixed.

[0130] According to the present invention, by providing a substantially U-shaped groove-like recess 7 in the center of the flat portion 9 of the peak portion 3 of the rectangular independent wave cable protective tube, it is possible to adjust the length of the rectangular independent wave cable protective tube and stabilize the structure of the cut end. As a result, it is possible to stabilize the structural strength of the male joint structure made at the cut end, and a stable male joint structure can be obtained even when a pull-out force is applied to the joint portion.

[0131] Also, the groove-shaped recess 7 can be used as an arrangement portion for the water-stopping member 17a, and it is possible to obtain a water-stopping structure in which a small water-stopping member 17a is arranged, or a double water-stopping structure using both the small water-stopping member 17a and the normal water-stopping member 17. Furthermore, since the groove-shaped recess 7 is a structure that supports the peak portion 3 from below, it has the effect of improving both the structural strength and flexibility of the rectangular independent wave cable protective pipe.

[0132] In addition, in the connection structure that connects the female joint member 15 and the independent wave cable protection tube 1 with adhesive, the adhesive is applied to the groove-shaped recess 7 at the same time as the peak 3 of the cable protection tube, and the adhesive is supplied from the groove-shaped recess 7 to the peak on the inner side of the cut end in addition to the adhesive initially applied to the surface, so that a stable adhesive strength is obtained between the female joint member 15 and the independent wave cable protection tube 1a. Therefore, in the case of a non-adhesive joint structure, the groove-shaped recess functions as a placement portion for a rubber water-stopping member, and in the case of an adhesive joint structure, it can be used as a supply portion for adhesive. Furthermore, when cutting adjacent cut ends, it functions as a cutting guide groove, allowing the cutting to be performed stably, and it can be seen that it has various effects as described above.

[0133] In addition, by making the pitch of the valleys 5 20 mm or more, a male joint structure using a retaining ring having a resin locking piece can be formed at the cut end. This allows the female joint structure to have less extra length compared to conventional female joint members, making it possible to achieve miniaturization. In this case, the wave pitch of the rectangular wave is 35 mm to 70 mm, and the smaller the ratio of the difference in height between the peaks 3 and the valleys 5 to the outer diameter of the tube, the more stable the strength of the locking piece of the retaining ring. Therefore, it is preferable that the ratio of the difference in height between the peaks 3 and the valleys 5 of the rectangular independent wave cable protective tube to the outer diameter of the tube is 6% to 10%.

[0134] By setting the ratio of the difference in height between the peaks 3 and the valleys 5 to the outer diameter of the pipe to between 6% and 10% and the wave pitch to between 35 mm and 70 mm, excessive flexibility can be suppressed and the inner diameter of the valleys 5 can be increased, so that the cable accommodation cross-sectional area rate can be expanded to the range of between 59% and 73% of the conventional accommodation cross-sectional area rate, while at the same time achieving weight reduction and cost reduction.

[0135] Although the embodiment of the present invention has been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can think of various modifications or alterations within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0136] 1, 1a………Independent wave cable protection tube 3. Yamabe 5. Valley 7...Groove-shaped recess 9……Flat area 10, 10a, 10b, 10c, 10d, 10e... Connection structure 11.…Knife 13, 13a……cut end 15, 15a, 15b...female joint members 16, 16a, 16b... Female joint structure 17, 17a...Water-stopping member 19...Slope section 21……Straight section 23, 23a, 23b, 23c, 23d... Male joint structure 25………Prevention ring 27a……First locking piece 27b……Second locking piece 29……basal part 31……Protrusion 33.... Fitting part 100………Independent wave cable protection tube 110, 110a... Connection structure

Claims

1. An independent wave cable protection tube made of a rigid polyvinyl chloride resin having a circular cross section perpendicular to the tube axis direction and a corrugated shape in which peaks and valleys are repeated in the tube axis direction, With respect to a tube axial direction of the independent wave cable protection tube, the mountain portion is rectangular and has a flat portion at a top thereof, and a groove-like recess having a substantially U-shape is provided at a center of the flat portion of the mountain portion, The independent wave cable protection pipe is characterized in that the groove-like recess is provided continuously on all of the peaks or on at least two or more of the peaks adjacent to each other in the tube axial direction.

2. The independent wave cable protection pipe according to claim 1, wherein the groove-like recesses are provided continuously on at least three or more of the crests adjacent to each other in the axial direction of the pipe.

3. a slope portion connecting the valley portion and the peak portion is formed between the valley portion and the peak portion with respect to a tube axial direction of the independent wave cable protection tube, a length from the center to the center of the inclined surface portions sandwiching the peak portion is longer than a length from the center to the center of the inclined surface portions sandwiching the valley portion, 2. The independent wave cable protection tube according to claim 1, characterized in that the valley portion and the inclined surface portions on both sides of the valley portion are formed in a substantially U-shape, or the valley portion has a linear portion that is shorter than the flat portion of the peak portion, and the valley portion and the inclined surface portions on both sides of the valley portion are formed in an inverted trapezoidal shape.

4. The independent wave cable protection tube according to claim 3, characterized in that a male joint structure is formed at an end of the independent wave cable protection tube, the independent wave cable protection tube being cut at the groove-shaped recess provided in the center of two or more consecutive crests provided at any position of the independent wave cable protection tube, and a rubber water-stopping member is attached to the valley portion adjacent to the cut crest portion, or in addition to the rubber water-stopping member, another small rubber water-stopping member is further provided in the groove-shaped recess of the crest portion adjacent to the valley portion.

5. a slope portion connecting the valley portion and the peak portion is formed between the valley portion and the peak portion with respect to a tube axial direction of the independent wave cable protection tube, 2. The independent wave cable protection tube according to claim 1, characterized in that the peaks and the valleys are formed in straight lines of approximately the same length in the tube axial direction, and a wave shape in which the peaks and the valleys are connected by the slopes has an approximately trapezoidal rectangular independent wave shape that is inverted symmetrically with respect to a center line passing through the slopes.

6. The independent wave cable protection tube has a pitch of the valley portion, which corresponds to a half pitch of the corrugated shape, of 20 mm or more, The independent wave cable protective tube is cut at the groove-shaped recess provided at the center of the crest at any position, and a ring-shaped or substantially C-shaped resin retaining ring is attached to the valley adjacent to the cut crest, The retaining ring has a first locking piece expanding in an oblique direction and a second locking piece parallel to the tube axial direction, and the first locking piece and the second locking piece have a structure extending from a base portion that is continuous in a circumferential direction, The independent wave cable protection tube according to claim 5, characterized in that a rubber water-stopping member is provided in at least one of the groove-shaped recesses of the peaks adjacent to the valleys or the next valley on the inner side of the tube adjacent to the valleys, thereby forming a male joint structure at the end of the independent wave cable protection tube.

7. The independent wave cable protective tube according to claim 5, characterized in that the tube outer diameter of the independent wave cable protective tube is appropriately set in the range of 120 mm to 300 mm, and the tube thickness is appropriately set in the range of 2.0 mm to 3.5 mm, so that the ratio of the height difference between the peaks and the valleys to the tube outer diameter of the peaks is 6% to 10%, and the wave pitch of the rectangular wave is 35 mm to 70 mm, thereby making it possible to reduce the length of the inclined surface portion and the number of the inclined surface portions per predetermined length of the independent wave cable protective tube, and suppress excessive flexibility.

8. The independent wave cable protection tube according to claim 7, characterized in that the accommodation cross-sectional area ratio, which is the ratio of the circular cross-sectional area of ​​the inner diameter of the independent wave cable protection tube at the valley portion to the circular cross-sectional area of ​​the outer diameter of the independent wave cable protection tube at the peak portion, can be set to 59% or more and 73% or less, thereby improving wire passing property and heat dissipation property.

9. The yield stress of the rigid polyvinyl chloride resin is 40.5 MPa or more, a depth of the groove-shaped recess provided at the center of the peak is equal to or less than half the difference in height between the peak and the valley of the independent wave cable protection tube, The independent wave cable protection tube according to claim 7 or 8, characterized in that the deflection rate as compressive strength measured by the method specified in the compressive strength test of JIS C 3653 Appendix 1 using the independent wave cable protection tube is 3.5% or less, and the stress generated in the independent wave cable protection tube at a buried depth of 5 m is 13.5 MPa or less, which is 1 / 3 or less of the breaking strength of the rigid polyvinyl chloride resin.

10. A connection structure between the independent wave cable protection tube and the female coupling member according to claim 3 or 5, The female joint member has female joint structures symmetrically arranged on both sides, The female joint structure has an inner circumferential surface that is substantially parallel in a longitudinal cross section, or has a taper that gradually reduces in diameter from one end toward the longitudinal center of the female joint member, The independent wave cable protection tube is cut at the groove-shaped recess provided at the center of the mountain portion at an arbitrary position of the independent wave cable protection tube, An adhesive is applied to the ridges near the cut ends, A connection structure between a female joint member and an independent-wave cable protection tube, characterized in that when the cut end of the independent-wave cable protection tube is inserted into the female joint structure, the center of the peak portion of the cut end is pressed against the inner surface of the female joint structure while being inserted, thereby connecting the female joint member and the independent-wave cable protection tube.

11. The connection structure between the independent wave cable protection tube and the female joint member according to claim 4, The female joint member has female joint structures symmetrically arranged on both sides, The female joint structure has an inner circumferential surface that is tapered in a longitudinal cross section such that the diameter of the inner circumferential surface gradually decreases slightly from one end toward the longitudinal center of the female joint member, A connection structure between a female joint member and an independent wave cable protection tube, characterized in that when the male joint structure is inserted into the female joint structure, the female joint member and the male joint structure are connected by pressing both the rubber water-stopping member of the male joint structure formed near the cut end of the independent wave cable protection tube and the other small rubber water-stopping member with the inner surface of the female joint structure.

12. The connection structure of claim 6 between the independent wave cable protection tube and the female joint member, The female joint member has female joint structures symmetrically arranged on both sides, The female joint structure has an inner circumferential surface in a longitudinal cross section having a protrusion protruding from one end toward a radial center at a predetermined position toward the longitudinal center of the female joint member, and a fitting portion expanding in diameter from a minimum inner diameter portion of the protrusion, the first locking piece of the resin-made anti-slip ring of the male joint structure formed in the vicinity of the cut end of the independent wave cable protection tube is pressed, and the male joint structure is inserted into the female joint structure, and then the end of the first locking piece that expands in an oblique direction of the elastically recovered anti-slip ring abuts against the fitting portion of the female joint structure, A connection structure between a female joint member and an independent wave cable protection tube, characterized in that the female joint member and the male joint structure are connected by pressing the rubber water-stopping member arranged in at least one of the groove-shaped recesses of the peak portion or the valley portion against the inner surface of the female joint structure.

13. A method for cutting an independent wave cable protection tube made of hard polyvinyl chloride resin, comprising the steps of: The independent wave cable protection tube has a cross section perpendicular to a tube axis direction that is circular, and has a wave shape in which peaks and valleys are repeated in the tube axis direction, With respect to a tube axial direction of the independent wave cable protection tube, the mountain portion is rectangular and has a flat portion at a top thereof, and a groove-shaped recess having a substantially U-shape is provided at a center of the flat portion of the mountain portion, the groove-like recess is provided continuously over the entire ridge portion or over at least two or more ridge portions adjacent to each other in the tube axis direction, A cutting method for an independent wave cable protection tube, comprising cutting the independent wave cable protection tube at the groove-shaped recess provided in the center of the peak portion at an arbitrary position of the independent wave cable protection tube.

14. A method for connecting an independent wave cable protection tube made of hard polyvinyl chloride resin to a female joint member, comprising: The female joint member has female joint structures symmetrically arranged on both sides, The independent wave cable protection tube has a cross section perpendicular to a tube axis direction that is circular, and has a wave shape in which peaks and valleys are repeated in the tube axis direction, With respect to a tube axial direction of the independent wave cable protection tube, the mountain portion is rectangular and has a flat portion at a top thereof, and a groove-shaped recess having a substantially U-shape is provided at a center of the flat portion of the mountain portion, the groove-like recess is provided continuously over the entire ridge portion or over at least two or more ridge portions adjacent to each other in the tube axis direction, The independent wave cable protection tube is cut at any one of the groove-shaped recesses, A method for connecting an independent-wave cable protection tube and a female joint member, comprising inserting a cut end of the independent-wave cable protection tube into the female joint structure to connect the female joint member and the independent-wave cable protection tube.

15. The method for connecting the independent wave cable protection tube and the female joint member according to claim 14, characterized in that, in a location where the groove-shaped recesses are provided in succession of three or more peaks, the independent wave cable protection tube is cut at the groove-shaped recesses of the peaks in the middle portion while leaving the groove-shaped recesses of the peaks at both ends.

16. The female joint structure has an inner circumferential surface that is substantially parallel in a longitudinal cross section, or has a taper that gradually reduces in diameter from one end toward the longitudinal center of the female joint member, The independent-wave cable protective tube has a slope portion between the valley portion and the peak portion and connecting the valley portion and the peak portion with respect to a tube axis direction of the independent-wave cable protective tube, a length from the center to the center of the inclined surface portions sandwiching the peak portion is longer than a length from the center to the center of the inclined surface portions sandwiching the valley portion, the valley portion and the slope portions on both sides of the valley portion are formed in a substantially U-shape, or the valley portion has a linear portion that is shorter than the flat portion of the peak portion, and the valley portion and the slope portions on both sides of the valley portion are formed in an inverted trapezoid shape, Applying an adhesive to the ridges near the cut ends; The method for connecting an independent-wave cable protection tube and a female joint member as described in claim 14, characterized in that the cut end of the independent-wave cable protection tube is inserted into the female joint structure, and the female joint member and the independent-wave cable protection tube are connected by inserting the cut end of the independent-wave cable protection tube into the female joint structure while pressing the inner surface of the female joint structure at the center of the crest of the cut end.

17. The female joint structure has an inner circumferential surface that gradually narrows slightly from one end toward the center in the longitudinal direction of the female joint member in a longitudinal cross section, The independent wave cable protective tube is cut at the groove-shaped recess provided in the center of the crest portion that is provided continuously at any position in two or more crests, a rubber water stop member is attached to the valley portion adjacent to the cut crest portion, and another small rubber water stop member is further provided in the groove-shaped recess of the crest portion adjacent to the valley portion, thereby forming a male joint structure at the end of the independent wave cable protective tube, The method for connecting an independent wave cable protection tube and a female joint member as described in claim 14, characterized in that the male joint structure of the independent wave cable protection tube is inserted into the female joint structure, and the rubber water-stopping member of the male joint structure and the other small rubber water-stopping member are both pressed against the inner surface of the female joint structure to connect the female joint member and the male joint structure.

18. The female joint structure has an inner circumferential surface in a longitudinal cross section having a protrusion protruding from one end toward a radial center at a predetermined position toward the longitudinal center of the female joint member, and a fitting portion expanding in diameter from a minimum inner diameter portion of the protrusion, The independent wave cable protection tube has a pitch of the valley portion, which corresponds to a half pitch of the corrugated shape, of 20 mm or more, cutting the independent wave cable protective tube at the groove-shaped recess provided at the center of the crest at any position of the independent wave cable protective tube, and attaching an annular or substantially C-shaped resin retaining ring to the valley adjacent to the cut crest, The retaining ring has a first locking piece expanding in an oblique direction and a second locking piece parallel to the tube axial direction, and the first locking piece and the second locking piece have a structure extending from a base portion that is continuous in a circumferential direction, a rubber waterproof member is provided in at least one of the groove-shaped recess of the peak portion adjacent to the valley portion or the next valley portion on the inner side of the tube adjacent to the valley portion, thereby forming a male joint structure at the end of the independent wave cable protection tube; the first locking piece of the retaining ring of the male joint structure is pressed, and the male joint structure is inserted into the female joint structure, and then an end of the first locking piece of the retaining ring that has elastically recovered and expanded in an oblique direction comes into contact with the fitting portion of the female joint structure, The method for connecting an independent wave cable protection tube and a female joint member as described in claim 14, characterized in that the female joint member and the male joint structure are connected by pressing the water-stopping member arranged in at least one of the groove-shaped recess of the peak portion or the valley portion against the inner surface of the female joint structure.

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