JP2009114596A - Tubular strand and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the flexibility of a tubular body as a core material of a tubular strand, thereby ensuring smooth grout injection into the tubular strand. <P>SOLUTION: A metallic tubular body 1 having its surface formed with multiple annular grooves, is passed through the center of a rotor 5 having wire feed bobbins 4 arranged circumferentially, and is inserted into the center holes of respective twisting mechanisms 6 and 7. Wires 2 are each inserted into the side wire holes of the respective twisting mechanisms 6 and 7. The rotor 5 and the respective twisting mechanisms 6 and 7 are revolved in the same direction to form a strand 14 by the twisting mechanism 6 at a first stage so as to circumscribe on an imaginary circle with a diameter larger than the outer diameter of the tubular body 1. Subsequently, the strand 14 is laid by the twisting mechanism 7 at a second stage so as to follow the outer circumferential surface of the tubular body 1 to reduce the stress from the wires 2 against the projections between the grooves in the surface of the tubular body 1 relative to that of a conventional one, thereby producing the tubular strand having a recessed amount of the projections of the tubular body 1, smaller than its wall thickness, with substantially no distortion of the inner circumferential profile. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tubular strand used as a tension material for a ground anchor, a prestressed concrete structure or the like, 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 hollow structure in which a tubular body 1 having flexibility is used as a core and a plurality of strands 2 are twisted along the outer peripheral surface thereof. The tension material (hereinafter referred to as “tubular strand”) has been proposed. Since this tubular strand can use the inside of the tubular body 1 as a grout injection passage, a stable fixing state can be secured 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 tubular body penetrating through the center of the rotating body and the wire unwound from each bobbin are guided to the center hole of the voice, and the respective strands are arranged on the outer peripheral surface of the tubular body. 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 strands are passed is formed around the central hole through which the tubular body is passed, and the strands are 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 tubular body.

  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, a thin-walled and relatively low-strength metal tube is used as an element tube of a tubular body serving 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 tubular body is not processed and thus has a lower strength than the groove part, and is deformed by receiving a large stress from the strand in the process of winding the strand around the tubular body. It's easy to do. Then, as shown in FIG. 4, when the dent amount of the convex portion of the tubular body 1 that contacts the element wire 2 is larger than the thickness of the tubular body 1 and the inner peripheral shape is deformed, the flexibility is lowered. In addition, the resistance of the flow of the grout injected into the tubular body 1 from the inner peripheral surface of the tubular body 1 is increased, which may hinder the grout injection. In contrast, it is conceivable to increase the thickness of the tubular body or use a high-strength material so that the deformation of the tubular body does not greatly 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-mentioned problems, the tubular strand of the present invention has a metal tubular body having a plurality of annular grooves or spiral grooves formed on the surface thereof as a core material, and has a diameter larger than the outer diameter of the tubular body. A twisted linear body composed of a plurality of strands twisted so as to circumscribe a virtual circle is twisted along the outer peripheral surface of the tubular body, and the amount of indentation of the convex portion between the grooves of the tubular body is tubular. It was assumed to be smaller than the thickness of the body.

  That is, by forming a structure in which a plurality of strands are twisted in two stages, the stress between the projections on the surface of the tubular body is smaller than that of the conventional one and the deformation of the tubular body is reduced. The inner peripheral shape is not greatly affected. By suppressing the deformation of the tubular body in this way, the flexibility of the tubular body is ensured and the grout can be smoothly injected into the inside thereof. When importance is attached to the strength of the tubular strand, the groove on the surface of the tubular body is preferably a spiral groove.

  Here, a corrugated pipe can be adopted as the metal tubular body.

  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 It can be made into the tubular strand which is hard to generate | occur | produce and is easy to store.

  When manufacturing the tubular strand having the above-described configuration, the bobbin around which the wire is wound is rotatably supported on the downstream side of the rotating body arranged in the circumferential direction, and the axial center hole of the bobbin is wound. A twisted wire mechanism having a plurality of side wire holes formed in the periphery is provided in two stages, and a tubular body penetrating the central portion of the rotating body is passed through the center hole of each twisted wire mechanism and unwound from each bobbin. One strand of wire is passed through each side wire hole of each twisted wire mechanism, and the rotating body and each twisted wire are pulled out to the downstream side of the second-stage twisted wire mechanism at a predetermined speed. After the wire mechanism is rotated in the same direction, a twisted wire body circumscribing a virtual circle having a diameter larger than the outer diameter of the tubular body is formed by the first-stage twisted wire mechanism, and then the second-stage twisted wire It is possible to adopt a method of twisting the stranded wire body along the outer peripheral surface of the tubular body by a mechanism. Kill.

  As described above, since the tubular strand of the present invention is obtained by reducing the deformation of the metal tubular body that is the core material, the flexibility of the tubular body is ensured, and the grout injection into the inside is smooth. Can be done.

  And according to the manufacturing method of the tubular strand of this invention, the tubular strand which has said characteristic can be manufactured reliably.

  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 tubular strand of embodiment. In this manufacturing process, the tubular body supply bobbin 3 around which the steel tubular body 1 is wound and the strand supply bobbin 4 around which the steel strand 2 is wound are arranged in the most upstream part along the circumferential direction. A rotating body 5 is provided. For the tubular body 1, a corrugated pipe having a steel type S10C (JIS G 4051), an outer diameter of 13 mm, a wall thickness of 0.7 mm, and annular grooves formed on the surface at a pitch of 6 mm is used. (JIS G 3502) with a wire diameter of 5.6 mm is used.

  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 has an inner diameter substantially the same as the outer diameter of the tubular body 1, and the side wire hole has 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.

  In the manufacturing method of the tubular strand by this manufacturing process, first, on the upstream side, the tubular body 1 unwound from the tubular body supply bobbin 3 is passed through the central portion of the rotating body 5 to form the central holes of the stranded wire mechanisms 6 and 7. The strands 2 unwound from the strand supply bobbins 4 are passed through the side wire holes of the twisting mechanisms 6 and 7 one by one. Then, while rotating the winder 13, the tubular body 1 and each strand 2 are pulled out to the downstream side of the second stage twisting mechanism 7 at a predetermined speed, and the rotating body 5 and each twisting mechanism 6, 7 are the same. Rotate in the direction. Thus, a stranded wire body 14 circumscribing the virtual circle A having a diameter larger than the outer diameter of the tubular body 1 is formed by the first-stage stranded wire mechanism 6 (FIG. 2A), and this stranded wire body. 14 is twisted along the outer peripheral surface of the tubular body 1 by the second-stage twisted wire mechanism 7 to form a nine-stranded tubular 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, and the strands of the strand 2 are temporarily loosened so that the tubular body 1 and the strand 2 are separated. To do. Then, in the process of twisting back the strand 2 on the downstream side of the loosening machine 9, the separated tubular body 1 and the strand 2 are each heated to 250 ° C. by the induction heating device 10, and then the electrostatic powder coating device 11. Then, an epoxy resin film 15 having an average thickness of 0.6 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 deformation state of the tubular body 1 was investigated for the strand thus produced (Example 1) and the strand (Example 2) produced in the same manner as in Example 1 using the tubular body 1 having a thickness of 0.5 mm. As a result, the indentations of the convex portions between the grooves on the surface were 0.1 mm and 0.2 mm, respectively, which were smaller than the wall thickness, and the inner peripheral shape was hardly deformed. On the other hand, when the same tubular body and strand as those of the examples are used, and manufactured by the same method as the normal stranded wire processing without using the first stage stranded wire mechanism 6 of the manufacturing process shown in FIG. In the strand having a thickness of 0.7 mm (Comparative Example 1), the convex portion of the tubular body is recessed by about 1 mm, and in the strand having a thickness of 0.5 mm (Comparative Example 2), the amount of dent in the convex portion of the tubular body is Further, the inner peripheral shape was greatly deformed as a whole. As a result, it has been confirmed that the manufacturing method of this embodiment can manufacture a tubular strand that can ensure flexibility more than before and can smoothly inject grout into the tubular body.

  In each comparative example, wear and cracks were generated on the surface of the tubular body. However, in each example, such damage to the surface of the tubular body was not observed, and it was also found that the life could be extended as compared with the comparative example.

  Next, using the same tubular body and wire as in Example 1, the strands without the synthetic resin coating treatment are manufactured without using the relieving machine 9 to the cooling device 12 in the manufacturing process shown in FIG. did. 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 surface of the tubular body 3 days later without the 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 tubular strand and the downstream process for performing the synthetic resin coating process may be separated and performed on separate manufacturing lines. For tubular strands used under severe corrosive conditions, it is preferable to apply a synthetic resin coating to both the tubular body and each strand as in the embodiment, but the use conditions are not so severe. In that case, a synthetic resin film may be formed on at least the outermost surface of the strand.

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

Explanation of symbols

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

Claims (4)

  A metal tubular body having a plurality of annular grooves or spiral grooves formed on the surface is used as a core material, and a twisted linear body composed of a plurality of strands is twisted along the outer peripheral surface of the tubular body, Tubular strands in which the amount of indentation at the protrusions between the grooves of the tubular body is smaller than the thickness of the tubular body.   The tubular strand according to claim 1, wherein the metal tubular body is a corrugated tube.   The tubular 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.   The method for manufacturing a tubular strand according to any one of claims 1 to 3, wherein the bobbin around which the strands are wound is rotatably supported downstream of a rotating body in which a plurality of bobbins are arranged along a circumferential direction. A twisted wire mechanism having a plurality of side wire holes formed around a central hole in the direction is provided in two stages, and a tubular body penetrating the central portion of the rotating body is passed through the center hole of each twisted wire mechanism, While passing the strands unwound from the bobbin one by one through the side wire holes of each twisted wire mechanism, pulling the tubular body and each strand at a predetermined speed to the downstream side of the second-stage twisted wire mechanism, After the rotating body and each twisted wire mechanism are rotated in the same direction, a twisted wire body circumscribing a virtual circle having a diameter larger than the outer diameter of the tubular body is formed by the first-stage twisted wire mechanism. The stranded wire body is twisted so as to be along the outer peripheral surface of the tubular body by the twisted wire mechanism of the step. Method of manufacturing a tubular strand and said and.

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