JP2009138365A - Polygonal strand and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polygonal strand capable of ensuring flexibility of a tubular body being a core member of tubular strand and allowing grout to be smoothly poured into its inside. <P>SOLUTION: In this polygonal strand manufacturing method, the metallic regular nonagonal pipe 1 provided with a plurality of annular grooves on its surface is used as the core member, nine metallic strands 2 are formed into a stranded wire-like body 14 circumscribed about a virtual circle A having larger diameter than that of a circle circumscribed about the regular nonagonal pipe 1 and being integral with it, and then the stranded wire-like bodies 14 are twined together along an outer peripheral face of the pipe 1 to manufacture the polygonal strand having depth of recessed part in a projecting part of the pipe 1 being smaller than wall thickness and causing hardly deformation of a shape of inner periphery without fail. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polygonal strand used as a tension material such as a ground anchor or a prestressed concrete structure, and a method for producing the same.

As tension materials such as ground anchors and prestressed concrete structures, solid steel PC bars and PC steel strands are usually used. However, when these solid tension materials are used as ground anchor materials, the anchor material is inserted into a hole excavated with several times its diameter, and a fixing grout is injected around it. There was a problem that the amount used was large. In addition, depending on the anchoring direction of the anchor material, the grout cannot be filled up to the deepest part of the excavated hole, and the anchor material may be unstable. In order to solve these problems, for example, as shown in FIG. 3, a circular tube 51 as a flexible tubular body is used as a core, and a plurality of strands 52 are twisted along the outer peripheral surface thereof. Combined hollow structure tension materials (hereinafter referred to as “tubular strands”) have been proposed. Since this tubular strand can use the inside of the circular tube 51 as a grout injection passage, a stable fixing state can be ensured regardless of the placement direction, and the cost can be reduced by reducing the amount of grout used (Patent Document 1). reference).
Japanese Patent Laid-Open No. 5-44301

  By the way, the above tubular strand is manufactured with the manufacturing method similar to a normal strand wire process. For example, as described in Patent Document 1 above, a twisted wire mechanism called a voice having a center hole on the downstream side of a rotating body in which a plurality of bobbins wound with strands are arranged along the circumferential direction. The pipes that penetrate the central part of the rotating body and the strands unwound from each bobbin are guided to the center hole of the voice, and the strands are arranged on the outer peripheral surface of the round pipe. A method of twisting by rotating the rotating body while drawing the wire to the downstream side of the voice at a predetermined speed can be adopted. Further, instead of the voice, a twisted wire mechanism in which a plurality of side wire holes through which the strand is passed is formed around the central hole through which the circular tube passes, and the strand wire mechanism is rotated in the same direction as the rotating body, There is also a method of twisting the two along the outer peripheral surface of the circular tube.

  However, in the tubular strand manufactured by the same manufacturing method as the normal stranded wire processing as described above, the following problems may occur. That is, since such a tubular strand requires a certain degree of flexibility and strength, use a thin, relatively low-strength metal made as a core tube of a circular tube as a core material. In many cases, a plurality of annular grooves or spiral grooves are formed on the surface by roller machining or the like from the outer peripheral side. In that case, the convex part between the grooves on the surface of the circular tube has not been processed, so the strength is lower than that of the groove part, and it is deformed by receiving a large stress from the wire in the process of winding the wire around the circular tube. It's easy to do. Then, as shown in FIG. 4, when the dent amount of the convex portion of the circular tube 51 in contact with the wire 52 is larger than the thickness of the circular tube 51 and the inner peripheral shape is deformed, the flexibility is lowered. In addition, the resistance that the flow of the grout injected into the circular pipe 51 receives from the inner peripheral surface of the circular pipe 51 is increased, which may hinder the grout injection. On the other hand, it is possible to increase the thickness of the circular tube or use a high-strength material so that the deformation of the circular tube does not significantly affect the inner peripheral shape. Since flexibility falls, it is not preferable.

  Therefore, an object of the present invention is to ensure the flexibility of the tubular body that is the core material of the tubular strand and to smoothly inject grout into the inside thereof.

  In order to solve the above problems, in the present invention, as a tubular strand, a metal polygonal tube having a plurality of annular grooves or spiral grooves formed on the surface thereof is used as a core, and the outer peripheral surface of the polygonal tube is formed on the core. Polygonal strands in which a plurality of strands were twisted so as to be along were adopted.

  In other words, since the polygonal tube is subjected to a relatively large process in the manufacturing process at the apex of the polygon, the convex part that is not subjected to surface grooving at the apex has a higher strength than the circular pipe. Yes. And when twisting the strands along the outer peripheral surface of the polygonal tube by the same manufacturing method as the normal stranded wire processing, since the vertex portion of the polygonal tube mainly receives stress from the strand, the polygonal tube is The deformation of the convex portion between the grooves hardly occurs, and the inner peripheral shape of the tube hardly changes. In this way, by using a polygonal tube as the tubular body that becomes the core material of the tubular strand and suppressing deformation of the tubular body, the flexibility of the tubular body is ensured and the grout can be smoothly injected into the inside thereof. become. When importance is attached to the strength of the polygonal strand, it is preferable that the groove on the polygonal tube surface is a spiral groove.

  Here, a corrugated tube can be adopted as the metal polygonal tube.

  In addition, when each of the strands is made of steel, by covering these steel strands with a synthetic resin, troubles such as delayed fracture due to rust of the steel strands even if left outdoors Polygon-shaped strands that do not easily occur and can be easily stored can be obtained.

  When manufacturing the polygonal strand having the above-described configuration, it is rotatably supported on the downstream side of the rotating body in which a plurality of bobbins around which the strands are wound are arranged along the circumferential direction, and the axial center hole is provided. A twisted wire mechanism having a plurality of side wire holes formed in the periphery is provided in two stages, and a polygonal tube penetrating the central portion of the rotating body is passed through the center hole of each twisted wire mechanism and wound from each bobbin. While passing the returned strands one by one through the side hole of each twisted wire mechanism, pulling out the polygonal tube and each strand at a predetermined speed to the downstream side of the second-stage twisted wire mechanism, the rotating body And the respective twisted wire mechanisms are rotated in the same direction to form an integral twisted wire body circumscribing the virtual circle containing the cross-sectional shape of the polygonal tube by the first-stage twisted wire mechanism. After the formation, the twisted wire body is twisted along the outer peripheral surface of the polygonal tube by the second-stage twisted wire mechanism. Then it is possible to employ a method go.

  That is, by dividing a plurality of strands into two stages and twisting them together, the stress received by the projections between the grooves on the polygonal tube surface from the strands is reduced compared to the conventional manufacturing method. The deformation of the tube can be made more difficult to occur.

  As described above, the polygonal strand of the present invention uses a highly deformation-resistant polygonal tube as a tubular body serving as a core material, and the tubular body is not easily deformed even if a manufacturing method similar to that of ordinary stranded wire processing is employed. Thus, the flexibility of the tubular body is ensured, and the grout can be smoothly injected into the inside thereof.

  And since the manufacturing method of the polygonal strand of this invention divided | segmented several strands in two steps and twisted together and made it difficult to produce a deformation | transformation of a polygonal tube, the polygon which has said characteristic more reliably. Shaped strands can be produced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the outline of the manufacturing process of the polygonal strand of embodiment. In this manufacturing process, a pipe supply bobbin 3 around which a steel regular hexagonal tube 1 is wound and an element wire supply bobbin 4 around which a steel element wire 2 is wound are provided in the most upstream portion along the circumferential direction. Individually arranged rotating bodies 5 are provided. The regular hexagonal tube 1 is a corrugated tube having a steel grade S10C (JIS G 4051), a circumscribed circle diameter of 13 mm, a wall thickness of 0.7 mm, and annular grooves formed on the surface at a pitch of 6 mm. The steel type is SWRS82B (JIS G 3502) and the wire diameter is 5.6 mm.

  Here, the regular hexagonal tube 1 can be manufactured by a known method as described in, for example, JP-A-56-1217. That is, eight V-notches are formed at equal intervals on one side of a thin steel plate as a raw material, and the thin steel plate as a raw material is disposed between a core mold having a ridge line that matches the V-notch and two clamping molds. By inserting and closing the clamping die, the thin steel plate is bent at each V notch to form a regular hexagon, and the side ends of the thin steel plates that are finally abutted with each other are seam welded to form a tubular body. That's fine.

  On the downstream side of the rotating body 5, twisted wire mechanisms 6 and 7 that are rotatably supported and have a plurality of side wire holes formed around the axial center hole are provided in two stages. The central hole is formed with an inner diameter substantially the same as the circumscribed circle diameter of the regular hexagonal tube 1, and the side wire hole is formed with an inner diameter substantially the same as the outer diameter of the strand 2. In addition, the side wire holes of the stranded wire mechanisms 6 and 7 are located on one circumference, respectively, and the first stage is arranged at a position farther from the center hole than the second stage.

  Then, on the downstream side of the second-stage twisted wire mechanism 7, a bluing heating furnace 8, a loosening machine 9, an induction heating device 10, an electrostatic powder coating device 11, and a cooling device 12 are provided in this order, and in the most downstream part A winder 13 is provided.

  The manufacturing method of the polygonal strand by this manufacturing process is as follows. First, on the upstream side, the regular hexagonal tube 1 unwound from the tube supply bobbin 3 is passed through the center of the rotating body 5 and the center of each twisted wire mechanism 6, 7. The strands 2 unwound from the strand supply bobbins 4 are passed through the holes and passed through the side wire holes of the stranded wire mechanisms 6 and 7 one by one. Then, the rotating body 5 and the stranded wire mechanisms 6 and 7 are moved in the same direction while the tube 1 and the strands 2 are pulled out to the downstream side of the second-stage stranded wire mechanism 7 at a predetermined speed by the rotation of the winder 13. Rotate to As a result, a stranded wire body 14 circumscribing the virtual circle A having a diameter larger than the circumscribed circle diameter of the tube 1 is formed by the first-stage stranded wire mechanism 6 (FIG. 2A). 14 is twisted along the outer peripheral surface of the tube 1 by the second-stage twisted wire mechanism 7 to form a nine-stranded polygonal strand (FIG. 2B). This is passed through the bluing heating furnace 8 and bluing is performed under the conditions of 350 ° C. × 30 seconds. The strand that has undergone the blueing treatment can be used as a product as it is, but in this embodiment, in order to improve the corrosion resistance, the synthetic resin coating treatment is subsequently performed in the downstream step as follows.

  In the downstream process, first, the strand that has passed through the brewing heating furnace 8 is passed through a loosening machine 9 to temporarily loosen the strands of the strand 2 so that the tube 1 and the strand 2 are separated. . Then, in the process of twisting back the strand 2 on the downstream side of the loosening machine 9, the separated tube 1 and the strand 2 are each heated to 260 ° C. by the induction heating device 10, and then passed through the electrostatic powder coating device 11. Then, an epoxy resin film 15 having an average thickness of 0.7 mm is applied to each surface (FIG. 2C). Finally, the strand from which the strand 2 is twisted back is cooled by the cooling device 12 and wound by the winder 13.

  The strands thus produced (Example 1) and the strands produced in the same manner as Example 1 (Example 2) using a 0.5 mm thick regular hexagonal tube were examined for the deformation state of the tube. However, the indentations of the convex portions between the grooves on the surface were 0.1 mm and 0.2 mm, respectively. Next, using the same regular hexagonal tube and strand as those in the above examples, the same method as that of normal stranded wire processing is used without using the first stage stranded wire mechanism 6 of the manufacturing process shown in FIG. When manufactured, the dent amount of the tube convex portion is 0.2 mm for the strand (Example 3) having a tube thickness of 0.7 mm, and 0.3 mm for the strand (Example 4) having a tube thickness of 0.5 mm. there were. That is, in any of the examples, the dent amount of the tube convex portion was smaller than the wall thickness, and the inner peripheral shape of the tube was hardly deformed.

  On the other hand, in the case where a circular tube having an outer diameter of 13 mm is used instead of the regular hexagonal tube of these examples and the same manufacturing method as in Examples 3 and 4 is employed (other conditions are the same as those in each example), In the strand having a thickness of 0.7 mm (Comparative Example 1), the convex portion of the tube is recessed by about 1 mm, and in the strand having a thickness of 0.5 mm (Comparative Example 2), the amount of concave portion of the tubular convex portion is further increased. Was greatly deformed as a whole.

  From these results, the polygonal strand using the polygonal tube as the core material has less deformation of the tube than the conventional tubular strand using the circular tube, is excellent in flexibility, and grout injection into the inside thereof is possible. It was confirmed that it could be done smoothly. It was also confirmed that the deformation of the polygonal tube of the polygonal strand can be further reduced by the manufacturing method of the embodiment.

  Furthermore, in each comparative example, the pipe surface was worn out or cracked, but in each example, such a pipe surface was not damaged, and it was found that the life could be extended as compared with the comparative example.

  Next, using the same regular hexagonal tube and strand as in Example 1, the strands in which the synthetic resin coating treatment is omitted without using the loosening machine 9 to the cooling device 12 in the manufacturing process shown in FIG. Manufactured. And when this strand without resin coating and the strand of Example 1 were allowed to stand outdoors under the same conditions, rust was generated on the tube surface after 3 days in the case of no resin coating. There was no outbreak. Thereby, the anti-corrosion improvement effect by the synthetic resin coating process of this embodiment was confirmed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the manufacturing process shown in FIG. 1, the upstream process for forming the polygonal strand and the downstream process for performing the synthetic resin coating process may be separated and performed on separate manufacturing lines. . For polygonal strands used under severe corrosive conditions, it is preferable to apply a synthetic resin coating to both the polygonal tube and each strand as in the embodiment, but the usage conditions are not so much. If it is not severe, a synthetic resin film may be formed on at least the outermost surface of the strand.

  In the present invention, a plurality of strands are twisted so as to be along the outer peripheral surface of the polygonal tube, but the strands are not twisted and arranged in parallel with the longitudinal direction of the strands, and are arranged at the front and rear ends and intermediate portions of the strands. In order to prevent the strands from spreading outward, a binding member such as a band may be provided on the outer periphery of the strand. In such a polygonal strand in which the strands are not twisted together, the polygonal tube is not deformed during the manufacturing process, so there is no possibility that the flexibility is impaired.

Schematic of manufacturing process of polygonal strand of embodiment a, b, and c are cross-sectional views showing the manufacturing process of polygonal strands in the manufacturing process of FIG. External perspective view showing the configuration of a conventional tubular strand Sectional view of tubular strand with deformed tubular body protrusion

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Regular hexagonal tube 2 Elementary wire 3, 4 Bobbin 5 Rotating body 6, 7 Twisted wire mechanism 8 Brewing heating furnace 9 Relaxation machine 10 Induction heating apparatus 11 Electrostatic powder coating apparatus 12 Cooling apparatus 13 Winding machine 14 Stranded wire Shape 15 Resin coating A Virtual circle

Claims (4)

  A polygonal strand in which a metal polygonal tube having a plurality of annular grooves or spiral grooves formed on the surface thereof is used as a core, and a plurality of strands are twisted along the outer peripheral surface of the polygonal tube.   The polygonal strand according to claim 1, wherein the metal polygonal tube is a corrugated tube.   The polygonal strand according to claim 1 or 2, wherein each of the strands is made of steel, and each of the strands of steel is coated with a synthetic resin.   In the manufacturing method of the polygonal strand according to any one of claims 1 to 3, it is rotatably supported on the downstream side of a rotating body in which a plurality of bobbins around which the strands are wound are arranged along the circumferential direction. A twisted wire mechanism in which a plurality of side wire holes are formed around an axial center hole is provided in two stages, and a polygonal tube penetrating the central portion of the rotating body is passed through the center hole of each twisted wire mechanism, The strands unwound from each bobbin are passed through the side wire holes of each twisted wire mechanism one by one, and the polygonal tube and each strand are pulled out to the downstream side of the second-stage twisted wire mechanism at a predetermined speed. However, by rotating the rotating body and each twisted wire mechanism in the same direction, the first strand twisted mechanism circumscribes each of the strands to a virtual circle that includes the cross-sectional shape of the polygonal tube. After forming the stranded wire, the stranded wire is removed from the outer periphery of the polygonal tube by a second-stage stranded wire mechanism. Method for manufacturing a polygonal strands, characterized in that go twisted as along.

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