Method for manufacturing tubular member

Abstract

To provide a method for manufacturing a tubular member, which can improve smoothness of a joint.SOLUTION: The method for manufacturing a tubular member extending along a center axis comprises helically winding a plate-like member about a center axis and forming the member into a tubular shape. The method comprises applying a laser beam to a butting part of the plate-like member formed into the tubular shape from outside the tubular member to laser-weld the butting part. The butting part is a butting portion of the helically extending ends of the plate-like member formed into the tubular shape. In the laser welding, the laser beam reciprocates between the plate-like members located on both sides about the butting part and is scanned along the butting part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a tubular member. [Background technology]

[0002] Patent Document 1 discloses a spiral steel pipe that is manufactured by spirally winding a strip of steel plate into a tubular shape and then laser welding the butt joints of the spirally extending ends of the steel plate from both the inner and outer surfaces of the pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-115890 Summary of the Invention [Problem to be solved by the invention]

[0004] When a steel sheet is wound into a tubular shape, compressive and tensile forces acting on the steel sheet cause warping at the widthwise ends of the steel sheet. Therefore, even when a steel sheet is wound spirally to form a tubular shape, as in the manufacturing method described above, warping occurs at the spirally extending ends of the steel sheet (i.e., the widthwise ends of the steel sheet). If the butt joints between the ends are laser-welded without eliminating this warping, there is a problem in that the seam is likely to be raised.

[0005] An object of one aspect of the present disclosure is to provide a method for manufacturing a tubular member that can improve the smoothness of a joint. [Means for solving the problem]

[0006] One aspect of the present disclosure is a method for manufacturing a tubular member extending along a central axis, the method comprising: winding a plate-shaped member spirally around the central axis to form a tubular shape. The method also comprises irradiating a butt joint of the tubular-shaped plate-shaped member with laser light from the outside of the tubular member to laser-weld the butt joint. The butt joint is a butt section between the spirally extending ends of the tubular-shaped plate-shaped member. In laser welding, a laser beam is scanned along the butt joint, moving back and forth between the plate-shaped members located on either side of the butt joint.

[0007] In this configuration, the laser beam scans the butt joint, melting each weld end that has warped outward from the tubular member due to the wrapping of the plate-like member, while stirring the molten metal at each weld end. This helps to eliminate the warping at each weld end. This prevents the butt joint from being laser-welded to form a raised seam. This improves the smoothness of the seam in the tubular member.

[0008] In one aspect of the present disclosure, the laser welding may be wobbling welding in which the laser beam is scanned along a path shaped like a series of circles. With this configuration, the movement of the laser light along a path shaped like a series of circles makes it easier to stir the molten metal at each welding end.

[0009] In one aspect of the present disclosure, the laser welding may be weaving welding in which the laser beam is scanned along a zigzag path. With this configuration, the movement of the laser light along the zigzag path tends to stir the molten metal at each welding end.

[0010] In one aspect of the present disclosure, the tubular member may be used in an automotive component. According to this configuration, it is possible to manufacture tubular automobile parts with improved smoothness of the joints. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a side view of the tubular member. [Figure 2] 1A to 1C are diagrams illustrating a method for manufacturing a tubular member. [Figure 3] Fig. 3A is a schematic cross-sectional view perpendicular to the central axis illustrating a first tensile force and a first compressive force that occur in the circumferential direction on the outer and inner surfaces when the plate-shaped member is rolled. Fig. 3B is a schematic diagram illustrating a second compressive force that occurs in the axial direction on the outer surface. Fig. 3C is a schematic diagram illustrating a second tensile force that occurs in the axial direction on the inner surface. Fig. 3D is a schematic cross-sectional view along the central axis illustrating warping that occurs at each weld end due to the second compressive force and the second tensile force. [Figure 4] 4A and 4B are schematic cross-sectional views taken along the central axis showing laser welding at the butt joint, respectively, and show a seam formed by laser welding. [Figure 5] FIG. 10 is a diagram illustrating wobbling welding. [Figure 6] FIG. 1 is a diagram illustrating weaving welding. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Configuration] The tubular member 100 shown in Fig. 1 is a cylindrical member extending along a central axis A. The tubular member 100 is used, for example, in automobile parts. Examples of automobile parts include vehicle body parts such as pillars and exhaust pipes.

[0013] As will be described in more detail later, as shown in FIG. 2, the tubular member 100 is manufactured by spirally winding a plate-shaped member 1 around a central axis A to form it into a tubular shape, and then joining adjacent welding ends 11, 12 of the plate-shaped member 1 together by laser welding.

[0014] The plate-shaped member 1 is, for example, a steel material, and has a tensile strength of 980 MPa or more. The plate-shaped member may be made of a metal other than steel. The plate-shaped member 1 is strip-shaped and extends in the longitudinal direction. In this embodiment, the length of the plate-shaped member 1 in the width direction perpendicular to the longitudinal direction is approximately constant. The length of the plate-shaped member in the width direction does not have to be constant.

[0015] The plate-like member 1 has welded ends 11 and 12, an outer surface 13, and an inner surface 14. Each of the weld ends 11, 12 is an end in the width direction of the plate-shaped member 1. Each of the weld ends 11, 12 extends spirally in the plate-shaped member 1 formed into a tubular shape (hereinafter referred to as the tubular plate-shaped member 1) and is in a state of abutting against each other in a direction along the central axis A (hereinafter referred to as the axial direction). In other words, the tubular plate-shaped member 1 has a butt joint 2. The butt joint 2 is the portion where the weld ends 11, 12 butt against each other.

[0016] The outer surface 13 is the surface that is located on the outside of the curve when the plate-shaped member 1 is rolled. The inner surface 14 is the surface that is located on the inside of the curve when the plate-shaped member 1 is rolled. In other words, the outer surface 13 forms the outer peripheral surface of the tubular member 100, and the inner surface 14 forms the inner peripheral surface of the tubular member 100.

[0017] A helically extending seam 3 is formed in the tubular member 100. The seam 3 is a portion where adjacent welded end portions 11, 12 are joined together by laser welding the butted portion 2.

[0018] [2. Manufacturing method of tubular member] Next, a method for manufacturing the tubular member 100 will be described with reference to FIG. First, the plate-shaped member 1 is continuously fed into a molding machine (not shown) along its longitudinal direction. Then, the molding machine feeds the plate-shaped member 1 along the central axis A while rotating the plate-shaped member 1 around the central axis A, whereby the plate-shaped member 1 is spirally wound and formed into a tubular shape.

[0019] 3A to 3D, when the plate-shaped member 1 is rolled, a first tensile force F1, a first compressive force F2, a second compressive force F3, and a second tensile force F4 are generated in the plate-shaped member 1, which tends to cause warping at the welded ends 11, 12 of the plate-shaped member 1. For ease of explanation, only a portion of the plate-shaped member 1 in the rolled state is simply shown in FIGS. 3A to 3D.

[0020] Specifically, as shown in FIG. 3A, when the plate-shaped member 1 is rolled, a first tensile force F1 is generated in the circumferential direction around the central axis A on the outer surface 13 of the plate-shaped member 1, and a first compressive force F2 is generated in the circumferential direction on the inner surface 14 of the plate-shaped member 1.

[0021] As shown in Figure 3B, the first tensile force F1 generates a second compressive force F3 in the axial direction on the outer surface 13. As shown in Figure 3C, the first compressive force F2 generates a second tensile force F4 in the axial direction on the inner surface 14.

[0022] As a result, as shown in Figure 3D, a second compressive force F3 occurs on the outer surface 13 and a second tensile force F4 occurs on the inner surface 14, causing the axial ends of the plate-like member 1 (i.e., each welded end 11, 12) to warp toward the outside of the tubular member 100.

[0023] Therefore, as shown in FIG. 4A, the welded ends 11, 12 at the butt joint 2 of the tubular plate-like member 1 are warped toward the outside of the tubular member 100.

[0024] Next, the butt joint 2 of the tubular plate-like member 1 is irradiated with laser light L from a laser irradiator 200 shown in FIG. 2 only from the outside of the tubular member 100, thereby laser welding the butt joint 2. As a result, adjacent weld ends 11, 12 are joined together, and a joint 3 is formed, as shown in FIG. 4B. In the present embodiment, as an example, the laser irradiator 200 is disposed above the tubular member 100, and the laser light L is irradiated onto the butt joint 2 from above and outside the tubular member 100. Note that the position at which the laser irradiator 200 is disposed with respect to the tubular member 100 may be other than above. That is, the laser light L may be irradiated onto the butt joint 2 from a direction other than above the tubular member 100.

[0025] In laser welding, laser light L is scanned along the butt joint 2, moving back and forth between the portions of the plate-like members 1 located on both sides of the butt joint 2. As a result, as shown in FIG. 4B , the warped weld ends 11, 12 melt while the molten metal at each of the weld ends 11, 12 is stirred, and each of the weld ends 11, 12 is melted so as to eliminate the warpage. In this embodiment, as shown in FIG. 5 , the laser welding is wobbling welding in which the laser light L is scanned along a path that resembles a series of circles (in other words, a spiral). By the laser welding described above, a tubular member 100 having a helically extending seam 3 formed therein is manufactured.

[0026] [3.Effects] According to the embodiment described above in detail, the following effects can be obtained. (3a) When the laser beam L is irradiated straight along the butt joint 2, the warping of the welded ends 11, 12 caused by winding the plate-shaped member 1 is not eliminated, and the welded ends 11, 12 are joined together, resulting in a raised seam. On the other hand, in this embodiment, the butt joint 2 is welded by wobbling welding. As a result, the welded ends 11, 12 that have warped due to winding the plate-shaped member 1 melt, and the molten metal at the welded ends 11, 12 is easily stirred, which makes it easy to eliminate the warping that occurred at the welded ends 11, 12. Therefore, welding the butt joint 2 by wobbling welding prevents the seam 3 from being raised. This improves the smoothness of the seam 3 in the tubular member 100.

[0027] (3b) In this embodiment, the laser light L is irradiated onto the butted portion 2 from above and outside the tubular member 100. That is, the laser light L is irradiated from above and in the direction in which each of the welded ends 11, 12 warps. This causes the molten metal at each of the welded ends 11, 12 to be stirred, and gravity makes it easier for the molten metal to melt and advance toward the inside of the tubular member 100. This makes it easier to melt each of the welded ends 11, 12 so as to eliminate the outward warping of the tubular member 100.

[0028] Furthermore, if the weld ends 11, 12 are joined together without eliminating the warpage of the weld ends 11, 12, irradiating the laser light L only from the outside of the tubular member 100 tends to make the joint inside the tubular member 100 at the butt joint 2 unstable. Therefore, to ensure the joint strength of the seam, it is necessary to irradiate the laser light L also from the inside of the tubular member 100. On the other hand, in this embodiment, as described above, wobbling welding makes it easy to melt the weld ends 11, 12 so as to eliminate the warpage of the weld ends 11, 12. Therefore, the joint inside the tubular member 100 at the butt joint 2 is prevented from becoming unstable. As a result, even if the laser light L is not irradiated from the inside of the tubular member 100, irradiating the laser light L only from the outside of the tubular member 100 tends to ensure the joint strength of the seam 3. Therefore, manufacturing costs can be reduced compared to when the laser light L is irradiated from both the outside and inside of the tubular member 100.

[0029] 4. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0030] (4a) In the above embodiment, the laser welding is wobbling welding. However, for example, the laser welding may be weaving welding in which the laser beam L is scanned along a zigzag path, as shown in Fig. 6. Even in this case, the same effects as those in (3a) and (3b) described above can be obtained.

[0031] (4b) In the above embodiment, the laser light L is irradiated to the butted portion 2 only from the outside of the tubular member 100. However, for example, the laser light L may be irradiated to the butted portion 2 from both the outside and inside of the tubular member 100.

[0032] (4c) In the above embodiment, the tubular member 100 is used as an automobile part, but the tubular member may be used as a part for purposes other than an automobile part, for example.

[0033] (4d) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0034] 1...plate-like member, 2...butt joint, 3...seam, 11, 12...welding end, 13...outer surface, 14...inner surface, 100...tubular member, 200...laser irradiator, A...center axis, F1...first tensile force, F2...first compressive force, F3...second compressive force, F4...second tensile force, L...laser light.

Claims

1. 1. A method for manufacturing a tubular member extending along a central axis, comprising: forming the plate-like member into a tubular shape by spirally winding the plate-like member around the central axis; irradiating a laser beam from outside the tubular member onto a butted portion of the plate-like member formed into a tubular shape, thereby laser welding the butted portion; Equipped with the butted portion is a butted portion between spirally extending ends of the plate-like member formed into a tubular shape, A method for manufacturing a tubular member, wherein in the laser welding, the laser light is scanned along the butted portion while moving back and forth between the plate-like members located on both sides of the butted portion, with the butted portion as the center.

2. A method for manufacturing a tubular member according to claim 1, comprising the steps of: A method for manufacturing a tubular member, wherein the laser welding is wobbling welding in which the laser light is scanned along a path shaped like a series of circles.

3. A method for manufacturing a tubular member according to claim 1, comprising the steps of: A method for manufacturing a tubular member, wherein the laser welding is weaving welding in which the laser light is scanned along a zigzag path.

4. A method for manufacturing a tubular member according to any one of claims 1 to 3, comprising: The tubular member is used as an automobile part. A method for manufacturing a tubular member.

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