JP2010223409A - Corrugated pipe and corrugated pipe connecting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrugated pipe with superior workability, and capable of efficiently improving compressive strength without impairing flexibility, and to provide a corrugated pipe connecting structure with superior water stop performance by using the corrugated pipe. <P>SOLUTION: The corrugated pipe 1 is a pipe body having flexibility. Ridge parts 3 and trough parts 5 are alternately formed on an outer circumference of the corrugated pipe 1. It is desirable that the corrugated pipe 1 is made of resin having flexibility, and for example, polyethylene can be used. The ridge part 3 and the trough part 5 have a substantially rectangular cross-sectional shape. A rib 7 is provided in a substantially center of the trough part 5. The rib 7 has a protruding shape toward a radial outer side of the corrugated pipe 1. In other words, the rib 7 protrudes toward the radial outer side of the corrugated pipe 1. The ribs 7 are formed along the trough parts 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a corrugated tube and a connection structure of corrugated tubes that are used for electric lines, water distribution pipes, etc., and have excellent compressive strength while maintaining flexibility.

  Conventionally, a corrugated tube used as a protective tube for an electric wire or the like is sometimes used by being buried in the ground below a road. Thus, vehicles can pass on the road on the corrugated pipe buried in the ground. In order to withstand a live load from a vehicle passing over the corrugated tube, the corrugated tube needs to be buried at a depth greater than a predetermined depth. On the other hand, by reducing the embedding depth, laying work becomes easy and the construction period can be shortened. In order to reduce the embedding depth of the corrugated tube, the compressive strength of the corrugated tube is insufficient, so a concrete protection method in which the periphery of the corrugated tube is hardened with concrete or a method of protecting with a resin block, etc. has been adopted. Yes.

  However, in the concrete protection system, man-hours are required for placing concrete and time is also required for road restoration. In addition, if a resin block is used, there is a problem that the cost is increased. Therefore, improvement of the compressive strength of the corrugated tube is desired.

  As such a corrugated tube having high strength, for example, there is a method of increasing the thickness of the corrugated tube itself. In addition, it is composed of two layers of inner and outer layers, defines the melt index of the inner and outer layers, uses high density polyethylene with relatively high fluidity for the outer layer, and corrugated with high density polyethylene with low fluidity for the inner layer There is a hard synthetic resin pipe (patent document 1).

  Moreover, there exists a corrugated pipe | tube which provided the peak part and the trough part, and arrange | positioned the reinforcement protrusion in parallel with the axial direction in the trough part of an outer peripheral wall (patent document 2).

JP 2007-139141 A JP-A-7-239065

  However, simply increasing the wall thickness will leave a wrap around when the corrugated tube is wound up, and the corrugated tube will meander and the cable will not be easily routed. Deteriorate.

  In addition, the corrugated hard synthetic resin tube described in Patent Document 1 has a multilayer structure for the corrugated tube and the material needs to be regulated, so that the manufacturing cost of the corrugated tube increases and the strength due to the material etc. There is a limit to the improvement.

  In addition, the corrugated tube described in Patent Document 2 is provided with protrusions in parallel in the axial direction in order to increase the strength, but the formation of such protrusions in the first place increases the linearity of the corrugated tube. This is for suppressing flexibility, and the flexibility of the corrugated tube is remarkably impaired also for the purpose. That is, the strength cannot be improved while ensuring flexibility.

  The present invention has been made in view of such problems, and has a corrugated tube that is excellent in workability and can efficiently improve the compressive strength without sacrificing flexibility, and the corrugated tube. An object of the present invention is to provide a connection structure for corrugated pipes having excellent water-stopping properties.

  In order to achieve the above-described object, the first invention is a corrugated tube in which crests and troughs are alternately formed on an outer peripheral portion, the corrugated tube having flexibility, The corrugated tube is characterized in that ribs are formed along the peaks and / or the valleys in the peaks and / or the valleys.

  It is desirable that the rib has a convex shape outward in the radial direction of the corrugated tube.

  The rib is provided at the bottom of the trough, the width of the rib is ½ or less of the width of the trough, and the height of the rib is from the bottom of the trough to the peak. It is desirable that the height is 1/2 or less of the height to the top.

  According to the first invention, since the rib is provided at the top of the peak or the bottom of the valley along the peak or valley, the compression strength is increased while maintaining flexibility by forming the rib. be able to. For this reason, a corrugated tube excellent in workability can be obtained.

  In addition, if the rib is convex toward the outside in the radial direction of the corrugated tube, it will not get caught when passing the cable inside, and when the corrugated tubes are connected by a pipe joint Also, water does not enter inside through the rib.

  Also, if the height of the rib is ½ or less of the height of the peak and the width of the rib is ½ or less of the width of the valley, the rib is There is no contact with the wall between the trough and the trough, and therefore flexibility does not deteriorate.

  A second invention is a tubular body connection structure for connecting corrugated tubes according to the first invention, having a corrugated shape corresponding to the corrugated shape of the corrugated tube, and having a sealing member on an inner peripheral surface. The pair of semi-cylindrical members are used, and the ends of the pair of corrugated tubes are sandwiched between the pair of semi-cylindrical members with the ends of the pair of corrugated tubes facing each other. By engaging the tubular members, the corrugated tubes are connected by covering the entire circumference of the corrugated tube with the pair of semi-cylindrical members, and the corrugated tubes are connected, The tubular body connection structure is characterized in that the rib is pressed against the seal member on the inner surface of the semi-cylindrical member, and water is stopped at the contact portion between the rib and the seal member.

  3rd invention is a pipe connection structure which connects the corrugated pipes concerning 1st invention, Comprising: The said corrugated pipe is a pipe with a spiral wave, The waveform corresponding to the spiral shape of the said corrugated pipe A cylindrical member having a shape and having a sealing member inside is inserted so that ends of the pair of corrugated tubes are opposed to both ends of the tubular member, and the tubular member and the corrugated tube And the corrugated tubes are connected to each other, and in a state where the corrugated tubes are connected to each other, the rib is pressed against the sealing member on the inner surface of the cylindrical member, and the rib and the sealing member The corrugated tube connection structure is characterized in that water is stopped at the contact portion.

  According to the second and third inventions, when corrugated tubes are connected to each other using a pipe joint that is a pair of semi-cylindrical members or a pipe joint that is a cylindrical member, the pipe joint is provided on the inner surface of the pipe joint. Since the seal member is pressed by the rib and the seal member and the rib come into strong contact with each other, the water stoppage at the contact portion between the rib and the seal member becomes extremely high. Therefore, the connection structure of the corrugated tube which is excellent in water-stopping property can be obtained.

  According to the present invention, a corrugated tube that is excellent in workability and capable of efficiently improving the compressive strength without sacrificing flexibility, and a corrugated tube that uses the corrugated tube and has excellent water blocking properties. A pipe connection structure can be provided.

The perspective view which shows the corrugated tube 1. FIG. It is a figure which shows the corrugated tube 1, (a) is sectional drawing, (b) is the A section enlarged view of (a). It is a figure which shows the state which bent the corrugated pipe | tube 1, (a) is a general view, (b) is the C section enlarged view of (a). The figure which shows the example of arrangement | positioning of the rib 7. FIG. The perspective view which shows the state which connects the corrugated pipes 1a and 1b by the half cylinder members 11a and 11b. It is a figure which shows the state by which the corrugated pipes 1a and 1b were connected by the pipe joint 19, (a) is sectional drawing, (b) is the D section enlarged view of (a). The perspective view which shows the state which connects the corrugated pipes 1c and 1d by the pipe joint 23. FIG. It is a figure which shows the state by which the corrugated pipes 1c and 1d were connected by the pipe joint 23, (a) is sectional drawing, (b) is the E section enlarged view of (a). Specimen No. The figure which shows arrangement | positioning of the rib of 1-6. The figure which shows the method of measuring the compressive strength of the test body 37. FIG. The figure which shows the method of measuring the flexibility of the test body.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a perspective view showing a corrugated tube 1 according to the present invention, FIG. 2 (a) is a sectional view of the corrugated tube 1, and FIG. 2 (b) is an enlarged view of a portion A in FIG. 2 (a). It is.

  The corrugated tube 1 is a flexible tube. On the outer periphery of the corrugated tube 1, peaks 3 and valleys 5 are alternately formed. In FIG. 1, the adjacent peak portions 3 and the valley portions 5 are independent from each other, but the peak portions 3 and the valley portions 5 may be continuously arranged in a spiral shape. The corrugated tube 1 is preferably made of a resin having flexibility, and for example, polyethylene can be used.

  As shown in FIG. 2A, the crest 3 and trough 5 have a substantially rectangular cross-sectional shape. A rib 7 is provided in the approximate center of the bottom of the valley 5. The rib 7 has a convex shape outward in the radial direction of the corrugated tube 1. That is, the rib 7 protrudes outward in the radial direction of the corrugated tube 1. The rib 7 is formed along the valley 5. That is, if the trough 5 is an independent groove, the adjacent ribs 7 are also formed independently. If the valley 5 is continuously provided in a spiral shape, the rib 7 is also continuously formed in a spiral shape. That is, the rib 7 is formed in the circumferential direction of the corrugated tube 1.

  As shown in FIG. 2 (b), the crest 3 and trough 5 on the outer periphery of the corrugated tube 1 are continuous by a wall 9. Here, the peak portion 3 refers to a range formed near the outermost peripheral portion of the corrugated tube 1, for example, substantially parallel to the axial direction of the corrugated tube 1, or a range including a predetermined curvature and R. . Similarly, the trough portion 5 indicates the range including the vicinity of the smallest diameter portion on the outer periphery of the corrugated tube 1, for example, substantially parallel to the axial direction of the corrugated tube 1, or including a predetermined curvature and R. .

  The rib 7 is formed at the approximate center of the valley 5. The width of the valley portion 9 (that is, the interval between the wall portions 9 and 9) is W, and the width of the rib 7 is w. In this case, the width w of the rib 7 is desirably 1/2 or less with respect to the width W of the valley portion 5.

  In addition, the height of the peak 3 (that is, the length from the bottom surface of the valley 5 to the top of the peak 3) is H, and the height of the rib 7 is h. In this case, the height h of the rib 7 is desirably 1/2 or less with respect to the height H of the peak portion 3.

  When the width w of the rib 7 exceeds 1/2 of the width W of the valley portion 5 and the height h of the rib 7 exceeds 1/2 of the height H of the peak portion 3, the corrugated tube 1 is flexible. This is because it adversely affects sex. The larger the width w and the height h of the rib 7, the greater the effect of improving the compressive strength.

  Next, the flexibility of the corrugated tube 1 will be described. FIGS. 3A and 3B are diagrams showing a state in which the corrugated tube 1 is bent. FIG. 3A is an overall view, and FIG. 3B is an enlarged view of a portion C in FIG.

  As described above, the corrugated tube 1 has flexibility. Since the corrugated tube 1 has flexibility, even a long corrugated tube can be easily stored and transported and can be laid. As shown in FIG. 3A, when the corrugated tube 1 is bent (in the direction of arrow B in the figure), the bending inner peripheral side (C portion in the figure) of the corrugated tube 1 is compressed and deformed.

  When the corrugated tube 1 is bent from a state where the corrugated tube 1 is straight, as shown in FIG. 3B, the adjacent peak portions 3 on the inner side of the bending are deformed so as to approach each other. Therefore, the rib 7 provided in the valley portion 5 is within the range surrounded by the valley portion 5 and the wall portion 9. At this time, since the height of the rib 7 is ½ or less of the height of the peak portion 3 and the width of the rib 7 is ½ or less of the width of the valley portion 5, the rib 7 There is no contact with the mountain 3. For this reason, the flexibility of the corrugated tube 1 is not greatly affected.

  In addition, in the corrugated tube 1 shown in FIGS. 1 to 3, the example in which the ribs 7 are provided in only one row in the valley portion 5 is shown, but the installation mode of the ribs 7 is not limited thereto. FIG. 4 is a diagram illustrating another arrangement example of the rib 7.

  For example, as shown in FIG. 4A, the rib 7 may be provided on the top of the peak portion 3. Even when the ribs 7 are provided on the crest 3, the ribs 7 are preferably convex outward in the radial direction of the corrugated tube 1. Similarly, the ribs 7 can be provided in both the mountain part 3 and the valley part 5.

  Further, as shown in FIG. 4B, a plurality of rows of ribs 7 may be provided. Even when the ribs 7 are provided in a plurality of rows, the installation range of the ribs 7 is ½ or less of the width of the valley 5, and the height of the ribs 7 is ½ or less of the height of the peaks 3. If there is, the influence on the flexibility of the corrugated tube 1 is small. As described above, the ribs 7 may be provided in any one or both of the valleys 5 and the peaks 3, and the ribs 7 are arranged in a row or in a circumferential direction (that is, along the peaks 3 and valleys 5). A row may be provided.

  In addition, the direction which provided the rib 7 only in the trough part 5 does not affect the outer diameter of a corrugated tube, and in the manufacturing process of the corrugated tube, a plurality of molds provided on the outer periphery of the material are used. Thus, when the corrugated tube is formed by sucking the material in the radial direction, it is possible to increase the thickness of the rib 7 if the rib 7 is provided at a position close to the center of the tube body. For this reason, it is more desirable to provide the rib 7 only in the trough part 5. In the following description, an embodiment in which the ribs 7 are provided in a row in the valley 5 will be described unless otherwise specified.

  Moreover, in the above Example, although the case where the cross-sectional shape of the peak part 3 of the corrugated tube 1 and the trough part 5 was a substantially rectangular shape was demonstrated, the cross-sectional shape of the peak part 3 and the trough part 5 is a substantially rectangular shape. Even in such a case, the rib 7 may be formed in the same manner. Similarly, even if the peak 3 and valley 5 have R portions at the corners, when connecting smoothly to a linear wall, the boundary between the peaks 3, valley 5 and wall 9 However, as shown in FIG. 4C, the peak 3 and the valley 5 are arcuate, and the boundary between the peak 3, the valley 5, and the wall 9 may be unclear.

  Even when the crest 3 and the trough 5 are arcuate (including a curved shape having a plurality of curvatures and a case where the corner has an R portion), the outer shape of the corrugated tube 1 is the crest 3 and trough. 5 and the wall 9, and the rib 7 may be provided in the valley 5 or the mountain 3 except for the wall 9. In other words, the ribs 7 may be provided on the peaks 3 and the valleys 5 that are portions other than the wall 9.

  For example, if the angle between the peak portion 3, the valley portion 5, the wall portion 9 and the axis of the corrugated tube 1 is in the range of 0 to 90 °, the peak portion 3 and the trough portion 5 are approximately the corrugated tube. A range having a curved surface close to parallel to the axial direction of 1 (for example, the trajectory at the thickness center from the center of the crest to the center of the trough in the axial section of the corrugated tube with respect to the axial direction of the corrugated tube 1 is 0 to 45. And the wall portion 9 has a range that is substantially perpendicular to the axial direction of the corrugated tube 1 across the inflection point (for example, the corrugated tube relative to the axial direction of the corrugated tube 1). The trajectory at the center of the thickness from the center of the peak to the center of the valley in the axial cross section can be 45 to 90 °).

  Next, a method for connecting the corrugated tube 1 will be described. FIG. 5 is a diagram illustrating a method of connecting a pair of corrugated tubes 1a and 1b. A pair of half-cylinder members 11a and 11b are used to connect the corrugated tubes 1a and 1b. The inner surfaces of the semi-cylindrical members 11a and 11b have a concave portion 15 and a convex portion 17 corresponding to the crest portion 3 and the trough portion 5 on the outer periphery of the corrugated tubes 1a and 1b, respectively.

  The crests 3 and troughs 5 of the corrugated tubes 1a and 1b may be in the form of independent waves or spiral waves, and the concave portions 15 and the convex portions 17 of the half-cylinder members 11a and 11b Accordingly, an independent wave shape or a spiral wave shape may be used. Further, seal members (not shown) are provided on the inner surfaces of the half-cylinder members 11a and 11b. The seal member will be described later.

  First, as shown in FIG. 5A, the half-cylinder members 11a and 11b are installed so as to be sandwiched from both sides with the corrugated tubes 1a and 1b facing each other. Flange 13 is provided in each side part of half cylinder members 11a and 11b. The flange 13 is provided with an engaging portion (not shown), and the flanges 13 of the half-cylinder members 11a and 11b can be engaged with each other.

  Next, as shown in FIG. 5 (b), the half cylinder members 11a and 11b are joined in a state where both end portions of the corrugated tubes 1a and 1b are sandwiched between the half cylinder portions 11a and 11b. The joining of the half cylinder members 11a and 11b may be performed by joining the flanges 13 using an engaging portion or an engaging member (not shown). In addition, what joined the half cylinder members 11a and 11b is called the pipe joint 19. FIG.

  6A is a cross-sectional view showing a state in which the corrugated pipes 1a and 1b are joined by the pipe joint 19, and FIG. 6B is an enlarged view of a portion D in FIG. 6A. As shown in FIG. 6B, the concave portion 15 and the convex portion 17 on the inner surface of the pipe joint 19 (seal member 21) are fitted and fixed to the peak portion 3 and the valley portion 5 of the corrugated tubes 1a and 1b. The outer peripheral surfaces of the corrugated pipes 1 a and 1 b are in contact with the seal member 21 on the inner surface of the pipe joint 19. The seal member 21 is an elastic member or a water-expandable member, and for example, rubber or nonwoven fabric can be used.

  The inner surface of the pipe joint 19 (seal member 21) has a shape corresponding to the crests 3 and troughs 5 of the corrugated pipes 1a and 1b, but the recesses corresponding to the ribs 7 are not provided. Therefore, the rib 7 opposes the convex part 17, and the clearance gap between the rib 7 and the convex part 17 becomes smaller than another site | part. For this reason, the sealing member 21 between the rib 7 and the convex part 17 is pressed strongly. That is, the water stoppage between the rib 7 and the seal member 21 can be increased.

  FIG. 7 is a diagram showing a case where another pipe joint 23 is used. The corrugated pipes 1 c and 1 d are corrugated pipes having a continuous spiral peak 3 and valley 5. Similarly to the pipe joint 19, the pipe joint 23, which is a tubular member, has spiral continuous concave and convex portions corresponding to the crests 3 and the valleys 5 on the outer periphery of the corrugated pipes 1c and 1d on the inner surface. . A seal member is provided on the inner surface of the pipe joint 23.

  First, as shown in FIG. 7A, the end portion of one corrugated tube (for example, corrugated tube 1c) is screwed into the pipe joint 23 with the corrugated tubes 1c and 1d facing each other. That is, the end portion of the corrugated pipe 1c is inserted into one opening of the pipe joint 23, and the corrugated pipe 1c and the pipe joint 23 are screwed together by screwing the pipe joint 23 into the corrugated pipe 1c.

  In a state where the end of the corrugated tube 1c is screwed to the vicinity of the opening on the side opposite to the insertion side of the pipe joint 23, the end portions of the corrugated tube 1c and the corrugated tube 1d are made to face each other. Further, the corrugated pipe 1d is inserted into the opening of the pipe joint 23 (the opening opposite to the side where the corrugated pipe 1c is inserted) to reverse the rotation direction of the pipe joint 23, so The tube 1d is screwed. At this time, the pipe joint 23 is screwed into the corrugated pipe 1d and moves in a direction of coming out of the corrugated pipe 1c. When the opposing portions of the corrugated pipes 1c and 1d have come to the approximate center of the pipe joint 23, the joining of the corrugated pipes 1c and 1d is completed (FIG. 7B).

  FIG. 8A is a cross-sectional view showing a state in which the corrugated pipes 1c and 1d are joined by the pipe joint 23, and FIG. 8B is an enlarged view of a portion E in FIG. 8A. As shown in FIG. 8B, the concave portion 27 and the convex portion 25 on the inner surface of the pipe joint 23 (seal member 29) are screwed and fixed to the crest portion 3 and the trough portion 5 of the corrugated tubes 1c and 1d. The outer peripheral surfaces of the corrugated pipes 1 c and 1 d are in contact with the seal member 29 on the inner face of the pipe joint 23. The seal member 29 is an elastic member or a water-expandable member, and for example, rubber or nonwoven fabric can be used.

  The inner surface of the pipe joint 23 (seal member 29) has a shape corresponding to the crests 3 and troughs 5 of the corrugated pipes 1c and 1d, but no recesses or the like corresponding to the ribs 7 are provided. Therefore, the rib 7 opposes the convex part 25, and the clearance gap between the rib 7 and the convex part 25 becomes smaller than another site | part. For this reason, the sealing member 21 between the rib 7 and the convex part 25 is strongly pressed. That is, the water stoppage between the rib 7 and the seal member 25 can be increased.

  As described above, according to the corrugated tube 1 according to the present invention, the rib 7 is provided along the trough 5 at the bottom of the trough 5, so that the corrugated tube 1 does not increase in thickness. The compressive strength of the tube 1 can be increased.

  Further, the corrugated tube 1 is bent because the height of the rib 7 is ½ or less of the height of the peak portion 3 and the width of the rib 7 is ½ or less of the width of the valley portion 5. Even in this case, the rib 7 does not come into contact with the peak portion 3 or the wall portion 9, and therefore the flexibility of the corrugated tube 1 does not deteriorate.

  Moreover, since the rib 7 has a convex shape toward the outer side in the radial direction of the corrugated tube 1, the rib 7 does not get caught when passing the cable inside. Even when the corrugated pipes are connected to each other by the pipe joint 19 including the pair of semi-cylindrical members 11 a and 11 b and the pipe joint 23 which is a cylindrical member, water does not enter the inside through the rib 7. In particular, when the corrugated pipes 1 are connected using the pipe joint 19 or the pipe joint 23, the seal members 21 and 29 provided on the inner surface of the pipe joint are pressed by the rib 7, and the seal members 21 and 29 and the rib 7 Therefore, the water stoppage at the contact portion between the rib 7 and the seal members 21 and 29 becomes extremely high. Therefore, the connection structure of the corrugated tube which is excellent in water-stopping property can be obtained.

  An evaluation test was conducted on the compressive strength and flexibility of the corrugated tube according to the present invention. FIG. 9 is a diagram showing a cross-sectional shape of a test specimen used for the test.

  Specimen No. 1-No. As 5, a corrugated tube having spiral peaks 30 and valleys 31 was used. Each test body was made of high-density polyethylene, and had a pipe outer diameter of 65 mm, a pipe inner diameter of 50 mm, a crest height of 5.5 mm, a trough width of 4.0 mm, and a crest pitch of 16.5 mm. The thickness of the specimen was 1.4 mm, and the tube weight was 320 g / m.

  Specimen No. 1 is provided with two rows of ribs 33 on the top of the crest 30. Specimen No. In FIG. 2, two rows of ribs 33 are provided on both the top of the crest 30 and the bottom of the trough 31. Specimen No. 3 has two rows of ribs 33 only in the valleys 31. Specimen No. 4 and Specimen No. Reference numeral 5 denotes a row of ribs 33 provided at the bottom of the valley 31. Specimen No. As a comparative example, 6 is a conventional one having no ribs.

  Specimen No. 1 to Specimen No. 1 The ribs 33 provided in No. 5 are all R-shaped. 1 to Specimen No. 1 No. 3 rib 33 has a height (width) of 0.5 mm. No. 4 rib 33 has a height (width) of 1.0 mm. The height (width) of the five ribs 33 was 1.5 mm. Specimen No. 1 to Specimen No. 1 Table 1 shows the configuration of the 6 ribs.

  The compressive strength of each specimen was measured according to the description in JIS C3653 Appendix 1. FIG. 10 is a diagram illustrating a method for measuring compressive strength. A test piece 37 having a length of 250 mm is sandwiched between a pair of flat plates 35a and 35b, a compressive load of 612N (arrow F in the figure) is applied from above the flat plate 35b, the deflection rate of the test piece 37 at this time is measured, and the compressive strength is measured. evaluated.

  Moreover, the flexibility of each test body was performed by the method shown in FIG. One end of the test body 39 was fixed in the vertical direction, and the test body 39 was bent along a bending frame 41 having a radius R that is five times (325 mm) the outer diameter of the test body. The length (L in the figure) at which the test body 37 is horizontal was set to 1 m, and a load was applied to the end of the test body 39 in the vertical direction (arrow G in the figure).

  In the state shown in FIG. 11, the bending load applied to the end of the test body 39 when the test body 39 was bent by 90 ° was measured, and the flexibility was evaluated. The compressive strength and flexibility measurement results are shown in Table 2, respectively.

  As is apparent from Table 2, the test specimen No. 1 to Specimen No. 1 The deflection rate of No. 5 is a comparative sample No. It can be seen that the compressive strength was improved by 10% or more with respect to the deflection rate of 6. Further, the deflection rate was further improved by increasing the height of the rib 33.

  On the other hand, the bending load is the test specimen No. 1 according to the present invention. 1 to Specimen No. 1 No. 5 and Comparative Example No. 6 is substantially the same although there is some variation, and by providing the rib 33, no significant increase in bending load was observed. In other words, the test body No. 1 to Specimen No. 1 The flexibility of No. 5 was almost the same as the conventional one, and the deterioration of flexibility was not seen by the rib 3.

  As described above, the corrugated tube according to the present invention can improve the compressive strength without deteriorating the flexibility. For this reason, for example, when a corrugated tube is buried under a road or the like, it can be used even at a shallower embedding depth without protection by concrete or the like.

  For example, the compression test load according to Annex 1 of JIS C3653 is calculated by converting the load applied when assuming a live load T-20 (20 t track) to a buried pipe with a buried depth of 300 mm, and further reducing the safety factor. It is specified that the deflection rate when this load is applied is 3.5% or less.

  Based on this, the test specimen No. 1 to Specimen No. 1 Based on the deflection rate of 5, the test body No. 1 to Specimen No. 1 The depth of burial at which the deflection rate of 5 is 3.5% was calculated backwards (For the calculation of the burial depth, the Journal of the Institute of Electrical Engineers, October 1988, pages 39-52 Refer to “Cable embedment depth”).

  Although the details of the calculation are omitted, assuming that a 20-t truck is running, the specimen No. with a deflection rate of 3.5% is obtained. 1 to Specimen No. 1 The embedding depth of 5 was about 200 mm. Therefore, by providing a rib on the corrugated tube 1, it can be used without performing concrete protection or the like even if the embedding depth is shallow from 300 mm to 200 mm. That is, if the corrugated tube according to the present invention is used, the embedding depth can be reduced and the laying operation is easy. Moreover, if it constructs with the same embedding depth, in order to obtain required compressive strength, since the thickness of the corrugated pipe | tube 1 can be reduced, weight reduction and cost reduction are possible.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, in consideration of improvement in compressive strength and securing of flexibility, the direction of the rib provided in the corrugated tube may be convex not only in the radial direction of the corrugated tube but also inward. . The cross-sectional shape of the rib is not limited to the embodiment, and may be any shape other than the rectangular shape and the R shape.

1, 1a, 1b, 1c, 1d ......... Wave tube 3 ......... Mountain 5 ......... Valley 7 ...... Rib 9 ......... Walls 11a, 11b ......... Semi-cylindrical member 13 ... ... Flanges 15, 27 ......... Concavities 17, 25 ......... Protrusions 19, 23 ......... Fittings 21, 29 ......... Seal member 30 ......... Mount 31 ......... Valley 33 ......... Rib 35a, 35b ......... Plates 37, 39 ......... Test body 41 ......... Bending frame

Claims (5)

A corrugated tube in which peaks and valleys are alternately formed on the outer periphery,
The corrugated tube has flexibility, and a rib is formed in the peak portion and / or the valley portion along the peak portion and / or the valley portion.   The corrugated tube according to claim 1, wherein the rib has a convex shape outward in a radial direction of the corrugated tube.   The rib is provided at the bottom of the trough, the width of the rib is ½ or less of the width of the trough, and the height of the rib is from the bottom of the trough to the peak. The corrugated tube according to claim 1, wherein the corrugated tube is not more than ½ of the height to the top. A tube connection structure for connecting the corrugated tubes according to any one of claims 1 to 3,
Using a pair of semi-cylindrical members having a corrugated shape corresponding to the corrugated shape of the corrugated tube, and having a seal member on the inner peripheral surface,
With the end portions of the pair of corrugated tubes facing each other, the end portions of the pair of corrugated tubes are sandwiched between the pair of semi-cylindrical members, and the pair of semi-cylindrical members are engaged with each other, The corrugated tubes are connected by covering the entire circumference of the corrugated tube with the pair of semi-cylindrical members,
In a state where the corrugated tubes are connected to each other, the rib is pressed against the sealing member on the inner surface of the semi-cylindrical member, and water is stopped at a contact portion between the rib and the sealing member. Body connection structure. A tube connection structure for connecting the corrugated tubes according to any one of claims 1 to 3,
The corrugated tube is a spiral corrugated tube, has a corrugated shape corresponding to the spiral shape of the corrugated tube, and uses a cylindrical member having a seal member inside,
The end portions of the pair of corrugated tubes are inserted so as to face each other from both ends of the tubular member, and the corrugated tubes are connected by screwing the tubular member and the corrugated tube,
In a state where the corrugated tubes are connected to each other, the rib is pressed against the sealing member on the inner surface of the cylindrical member, and water is stopped at the contact portion between the rib and the sealing member. Pipe connection structure.

Images