Gas-pressure welding steel material and gas-pressure welding method

Abstract

To provide a gas-pressure welding steel material and a gas-pressure welding method, which can suppress the occurrence of oxidation reaction during gas-pressure welding by a simple constitution.SOLUTION: A gas-pressure welding steel material 1 for being used with a reduction material in an axially butting state during gas-pressure welding comprises a rod-like body part 10 that extends along an axial direction, and a joint part 20 that is provided on the side of one end in the axial direction of the body part 10. A recess 21 depressed on the side of the body part 10 is formed in the joint part 20. During the gas-pressure welding, the pair of steel materials 1 is pressurized in a butting state.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a steel material for gas pressure welding and a gas pressure welding method using the same. [Background technology]

[0002] Conventionally, gas pressure welding has been performed in which a pair of steel materials are placed opposite each other on the same axis, and the steel materials are pressure-welded together in the axial direction while being heated with a gas flame to integrate the two. During gas pressure welding, the ends of the pair of steel materials are brought into contact with each other, and the contact area is heated with a gas flame to heat the joint. However, since the ends of the pair of steel materials, which already have a gap, are brought close to each other, oxygen is likely to enter during heating.

[0003] If oxides remain at the joint between a pair of steel materials, the metallurgical bond between the steel materials will not function properly, and the strength of the integrated steel materials will decrease. Therefore, various methods have been used to suppress oxidation at joints where gaps are likely to form.

[0004] For example, Patent Document 1 discloses a ring-shaped holding member used to prevent oxidation of the joint when gas pressure welding steel materials. The ring-shaped holding member is made of a thermoplastic polystyrene resin. The ring-shaped holding member is attached to the end face of the steel material, and when heated by a gas flame, the ring-shaped holding member vaporizes to generate reducing gas, thereby preventing oxidation of the joint. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5197652 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in the gas pressure welding described in Patent Document 1, steel materials are integrated via an annular body housed in an annular body holding member, but further ingenuity is required to prevent oxidation in order to improve the strength of the steel materials after joining.

[0007] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steel material for gas pressure welding and a gas pressure welding method that can suppress the occurrence of oxidation reactions during gas pressure welding with a simple configuration. [Means for solving the problem]

[0008] In response to the above-mentioned problems, the gas pressure welding steel material of the present invention is a gas pressure welding steel material that is used in an axially butted state during gas pressure welding, and is characterized in that it comprises a rod-shaped main body extending along the axial direction and a joint portion provided on one end side of the main body in the axial direction, and the joint portion has a recess formed that is recessed toward the main body portion.

[0009] Here, it is preferable that the recess is formed in an arc shape that curves toward the main body portion in a cross-sectional view, and that the recess is formed in an isosceles triangle shape with the main body portion as the apex in a cross-sectional view, and that the recess is formed in a square shape in a cross-sectional view.

[0010] It is also preferable that the joint portion has a thin-walled portion formed in an annular shape when viewed in the axial direction, and that the thin-walled portion has an air hole formed therein that penetrates through in the thickness direction.

[0011] The invention of a gas pressure welding method is a gas pressure welding method using any of the above-described steel materials for gas pressure welding, characterized in that it comprises the steps of butting a pair of the steel materials for gas pressure welding with the joints facing each other and placing a reducing material in the space formed by the joints, and pressurizing the pair of butted steel materials for gas pressure welding along the axial direction. [Effects of the Invention]

[0012] As described above, the steel material for gas pressure welding of the present invention comprises a rod-shaped main body extending along the axial direction and a joint provided at one axial end of the main body, and the joint is formed with a recess that is recessed toward the main body. This allows the formation of a recess at the joint between the steel materials and prevents air from entering the space formed by the recess during the joining operation. Therefore, the occurrence of an oxidation reaction during gas pressure welding can be suppressed with a simple configuration.

[0013] Here, it is desirable that the recess formed in the joint be one of the following shapes: an arc-shaped recess that curves toward the main body in cross section, an isosceles triangle with the main body as the apex in cross section, or a square in cross section. Therefore, regardless of the shape of the recess formed in the joint, it is possible to form a recess at the joint between the steel materials and prevent air from entering the space formed by the recess during the joining operation, thereby making it possible to suppress the occurrence of an oxidation reaction during gas pressure welding with a simple configuration.

[0014] In addition, the joint has a thin-walled portion formed in an annular shape when viewed in the axial direction, and the thin-walled portion has a vent hole formed therethrough in the thickness direction. Therefore, by joining the joints together, the space formed inside the recess can be connected to the space outside the steel material. Therefore, reducing gas generated during the joining operation can be released to the outside of the steel material.

[0015] In a gas pressure welding method using a steel material for gas pressure welding, a pair of steel materials are butted together with their joints facing each other, and a reducing agent is placed in the space formed by the joints, and the pair of steel materials are then pressurized in the axial direction. This allows the pair of steel materials to be joined by softening a part of the main body as well as the thin-walled portion formed outside the recess. Therefore, the oxidation reaction during gas pressure welding can be suppressed with a simple configuration. [Brief explanation of the drawings]

[0016] [Figure 1]1A is a perspective view of a steel material for gas pressure welding according to an embodiment of the present invention, and FIG. 1B is a longitudinal sectional view taken along the axial direction of the steel material for gas pressure welding. [Figure 2] FIG. 2 is a view of a steel material for gas pressure welding as viewed from the axial direction. [Figure 3] FIG. [Figure 4] 1(a) is a longitudinal sectional view of a steel material for gas pressure welding according to a first modified example, and FIG. 1(b) is a longitudinal sectional view of a steel material for gas pressure welding according to a second modified example. [Figure 5] FIG. 1(a) is a diagram showing the state before the joining work starts, and FIG. 1(b) is a diagram showing the state during the joining work. [Figure 6] FIG. 10 is a diagram showing the state in which steel materials are welded together. [Figure 7] 1(a) is a perspective view of a rail member including a steel material according to a modified example, and FIG. 1(b) is a cross-sectional view taken along the arrow AA. [Figure 8] FIG. 10 is a diagram showing a state in which steel materials according to a modified example are joined together. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] Fig. 1(a) is a perspective view of a steel material for gas pressure welding 1 (hereinafter simply referred to as "steel material 1") according to an embodiment, Fig. 1(b) is a longitudinal cross-sectional view along the axial direction of the steel material 1, and Fig. 2 is a side view of the steel material 1 as viewed from the axial direction. The steel material 1 is configured to have a main body portion 10 extending in a rod-like shape in the axial direction, and a joint portion 20 provided on one end side of the main body portion.

[0019] The main body 10 is a rod-shaped member formed into a substantially cylindrical shape, and is made of steel such as deformed reinforcing bars or steel rods. The joints 20 are provided integrally with the main body 10 along the axial direction.

[0020] The joint portion 20 is formed with a recess 21 recessed toward the main body portion 10. The recess 21 is circular when viewed in the axial direction, and is formed in an arc shape curved toward the main body portion 10 when viewed in cross section.

[0021] The joint 20 has a thin-walled portion 22 formed in an annular shape when viewed in the axial direction by the recess 21. The thin-walled portion 22 has a uniform thickness in the circumferential direction, and the thickness gradually increases as it moves axially toward the main body 10. The thin-walled portion 22 has ventilation holes 23 cut into it at any part in the circumferential direction.

[0022] 3 is a side view of an example of a drilling jig 80. The drilling jig 80 is configured to have a shaft portion 81 and a spherically formed head portion 82 provided on one end of the shaft portion. For example, by rotating the head portion 82 of the drilling jig 80 while it is pressed against the joint portion 20 and moving it toward the main body portion 10, it is possible to form a recess 21 in the joint portion 20 that has a curved surface that curves toward the main body portion 10.

[0023] Fig. 4(a) is a longitudinal cross-sectional view of a steel material (steel material for gas pressure welding) 1A according to a first modified example, and Fig. 4(b) is a longitudinal cross-sectional view along the axial direction of a steel material (steel material for gas pressure welding) 1B according to a second modified example. In the first and second modified examples, the same components as those in the above embodiment are given the same reference numerals, and detailed explanations thereof will be omitted.

[0024] As shown in Fig. 4(a), the steel material 1A has a main body portion 10 and a joint portion 20, and a recess 21a is formed in the joint portion 20. The recess 21a is circular when viewed in the axial direction and is formed in the shape of an isosceles triangle with the main body portion 10 side as the vertex when viewed in cross section.

[0025] As shown in Fig. 4(b), the steel material 1B has a main body 10 and a joint 20, and a recess 21b is formed in the joint 20. The recess 21b is circular when viewed in the axial direction and rectangular when viewed in cross section.

[0026] In this way, in the steel material 1A according to the first modification and the steel material 1B according to the second modification, it is sufficient that a concave space is formed on one end side in the axial direction. Note that the three-dimensional shape of the concave portion 21 formed in the joint 20 may be any shape, such as a hemisphere, a cone, or a cylinder.

[0027] Next, a gas pressure welding method using the steel material 1 according to the embodiment will be described. Fig. 5(a) is a diagram schematically showing the state of the welded joint 20 before it is softened, and Fig. 5(b) is a diagram showing the state of the welded joint 20 after it has been softened.

[0028] As shown in Fig. 5(a), before starting the joining operation, a pair of steel materials 1 are butted together with their joints 20 facing each other. A space S is formed by a recess 21 formed by the pair of joints 20, and a reducing agent 50 is placed inside the space S. Note that, at the time of joining, one of the steel materials 1 may have a flat end face on which no recess 21 is formed.

[0029] The reducing material 50 is, for example, a member formed in a sheet shape, and may have dimensions large enough to fit inside the space S. The thickness of the reducing material 50 is desirably about 0.1 mm to 1.0 mm. The reducing material 50 is not limited to a sheet shape, and may be in the form of a powder, a paste, or even a liquid. Furthermore, the reducing material 50 may be formed in the shape of a cap that can be placed on the end of the steel material 1.

[0030] The reducing agent 50 is preferably made of a synthetic resin such as polystyrene, polyethylene, or polypropylene, but may be made of any material as long as it generates a reducing gas when heated. In the following description, the reducing agent 50 is assumed to be made of polystyrene resin.

[0031] As shown in Figure 5(b), as the joining operation begins (softening of the joint 20), the steel materials 1 are pressed from both axial sides while the joining portion of the steel materials 1 is heated by a burner flame (fire). Note that the white arrows in the figure schematically show the flames, and the black arrows show the direction of pressure being applied to the steel materials 1. To achieve the pressurized state, both steel materials 1, 1 may be pressed against each other, or one steel material 1 may be fixed and the other steel material 1 may be pressed against it.

[0032] The joint portion of the steel materials 1 is heated by the flame, which causes a rise in temperature of the joint 20 and heating of the reducing agent 50. As the temperature of the joint 20 rises, the thin-walled portion 22, which is pressed along the axial direction, softens. As the thin-walled portion 22 softens, the inner space S gradually shrinks and the thin-walled portion 22 bulges radially outward, forming a bulge 30. Then, as the joint 20 and one end of the main body portion 10 soften to the extent that the space S disappears, the end faces of the steel materials 1 are joined together and the pair of steel materials 1 are integrated.

[0033] During gas pressure welding, reducing gas is generated as the reducing material 50 is heated by the flame, and the reducing gas fills the space S. The generated reducing gas expands and flows out of the space S (to the outside air side) through the ventilation hole 23. Note that the reducing material 50 is gasified and disappears as the welding progresses.

[0034] In this way, when the reducing material 50 made of polystyrene resin is heated, the polystyrene vaporizes and a reducing gas is generated. When the reducing gas is generated, the internal pressure of the space S increases, and it is possible to physically block air from entering the space S. Furthermore, since the reducing gas remains at the end face of the steel material 1, it is possible to prevent oxidation of the end face of the steel material 1. This suppresses the generation of oxides on the end face of the steel material 1, promotes integration of the steel materials 1, and improves the strength after joining.

[0035] Fig. 6 is a diagram showing a state in which steel materials 1, 1 are joined together. As shown in Fig. 6, after joining, a structure 2 is formed in which the pair of steel materials 1, 1 are integrated. The structure 2 is formed in a substantially cylindrical shape, and a bulge 30 is formed in part of it over the entire circumferential direction. The bulge 30 is caused by the thin-walled portion 22 and part of the main body portion 10 after joining, and is a so-called pressure-welded bump.

[0036] As described above, the steel material for gas pressure welding 1 of the embodiment comprises a rod-shaped main body 10 extending along the axial direction, and a joint 20 provided at one end of the main body 10 in the axial direction, and a recess 21 recessed toward the main body 10 is formed in the joint 20. As a result, the recess 21 is formed at the joint between the steel materials 1, and it is possible to prevent air from entering the space S formed by the recess 21 during the joining operation. Therefore, with a simple configuration, it is possible to suppress the occurrence of an oxidation reaction during gas pressure welding.

[0037] Here, it is desirable that the recess 21 formed in the joint be formed in any one of the following shapes: an arc shape curving toward the main body 10 in cross section, an isosceles triangle shape with the main body 10 side at the apex in cross section, or a square shape in cross section. Therefore, regardless of the shape of the recess 21 formed in the joint 20, the recess 21 can be formed at the joint between the steel materials 1, and air can be prevented from entering the space S formed by the recess 21 during the joining operation, making it possible to suppress the occurrence of an oxidation reaction during gas pressure welding with a simple configuration.

[0038] Furthermore, the joint 20 has a thin-walled portion 22 formed in an annular shape when viewed in the axial direction, and the thin-walled portion 22 has an air vent 23 formed therethrough in the thickness direction. Therefore, by butting the steel materials 1 together and joining the joints 20 together, the space S formed inside the recess 21 can be made to communicate with the space outside the steel materials 1. Therefore, the reducing gas generated during the joining operation can be released to the outside of the steel materials 1.

[0039] (Variation) Next, a description will be given of a modified example of the steel material for gas pressure welding 1 according to the embodiment. Fig. 7(a) is a perspective view of a rail member 100 including a steel material (steel material for gas pressure welding) 101 according to the modified example, and Fig. 7(b) is a cross-sectional view taken along the arrow AA.

[0040] The rail member 100 is configured to include a steel material 101, a leg portion 150 extending linearly downward from the lower end of the steel material 101, and a floor portion 160 provided below the leg portion 150. The steel material 101 has a rod-shaped main body portion 110 extending horizontally and a joint portion 120 provided on one side of the main body portion 110.

[0041] The joint 120 is formed with a recess 121 recessed toward the main body 110. The recess 121 is circular when viewed in the axial direction, and is formed in an arc shape curving toward the main body 110 when viewed in cross section. The joint 120 is formed with a thin-walled portion 122 formed by the recess 121 in a ring shape when viewed in the axial direction. The thin-walled portion 122 is formed with an air hole 123 penetrating in the thickness direction.

[0042] Figure 8 is a diagram showing a state in which rail members 100, 100 are joined together by gas pressure welding. As in the previous embodiment, after the joining operation is completed, a structure 200 is formed in which the pair of rail members 100, 100 are integrated. At the joint between the rail members 100, 100, a bulge 230 is formed as a pressure-welded bump that protrudes in a direction perpendicular to the axial direction. Note that in Figure 8, the bulge 230 is shown in an exaggerated manner.

[0043] Thus, 101 provided as a part of the rail member 100 according to the modified example comprises a rod-shaped main body 110 extending along the axial direction and a joint 120 provided on one axial end of the main body 110, with a recess 121 formed in the joint 120 that is recessed toward the main body 110. Therefore, regardless of the dimensions or shape of the joint, it is possible to prevent air from entering the space formed by the recess 21 during the joining operation. Therefore, with a simple configuration, it is possible to suppress the occurrence of an oxidation reaction during gas pressure welding.

[0044] Each embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to these embodiments, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0045] For example, in the above embodiment, a case has been described in which recesses 21, 21 are provided in each of the two steel materials 1, 1 that are butted together, but this is not limited to this, and it is sufficient that a recess 21 is formed in either one of the steel materials 1 that are butted together.

[0046] Furthermore, the shapes of a pair of recesses 21 formed in the butted steel materials 1 may be different from each other. For example, the recess 21 formed in one steel material 1 may be arc-shaped in cross section, and the recess 21 formed in the other steel material 1 may be rectangular in cross section. [Explanation of symbols]

[0047] 1: Steel (gas pressure welding steel) 10: Main body 20: Joint 21: Recess 22: Thin section 23: Ventilation hole 50: Reducing material

Claims

1. A steel material for gas pressure welding that is used in an axially butted state during gas pressure welding, a rod-shaped main body portion extending along the axial direction; a joint portion provided on one end side of the main body portion in the axial direction, A steel material for gas pressure welding, characterized in that a recess that is recessed toward the main body portion is formed in the joint portion.

2. 2. The steel material for gas pressure welding according to claim 1, wherein the recess is formed in an arc shape that curves toward the main body portion in a cross-sectional view.

3. 2. The steel material for gas pressure welding according to claim 1, wherein the recess is formed in an isosceles triangle shape with the main body side being the apex side in a cross-sectional view.

4. 2. The steel material for gas pressure welding according to claim 1, wherein the recess is formed in a rectangular shape in cross section.

5. A steel material for gas pressure welding as described in any one of claims 1 to 4, characterized in that the joint has a thin-walled portion formed in a ring shape when viewed axially, and the thin-walled portion has an air vent formed therein that penetrates in the thickness direction.

6. A gas pressure welding method using the gas pressure welding steel material according to any one of claims 1 to 4, a step of butting the pair of steel materials for gas pressure welding together with the joints facing each other and placing a reducing material in a space formed by the joints; and applying pressure to the pair of butted steel materials for gas pressure welding in the axial direction.

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