Method for manufacturing laser-welded structures
The method addresses distortion in laser-welded structures by analyzing width stiffness to determine optimal welding lines, reducing warping and ensuring proper welding quality in elongated and bent plate-like members.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JMAX
- Filing Date
- 2024-10-03
- Publication Date
- 2026-05-20
AI Technical Summary
Conventional laser welding of plate-like members results in distortion due to thermal shrinkage, particularly in the plate width direction, which affects the quality of the welded structure, especially when continuous welding over longer distances.
A method involving a width stiffness analysis step to determine optimal welding lines based on the rigidity of plate-shaped members, followed by laser welding along these lines to minimize distortion, ensuring equal rigidity in divided sections.
The method reduces distortion in the plate width direction by balancing the rigidity of divided sections, allowing for proper laser welding without significant warping, even in elongated and bent structures.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a laser welded structure and a laser welded structure.
Background Art
[0002] Conventionally, there have been disclosed a method for manufacturing a laser welded structure and a laser welded structure in which plate-like members are stacked and laser welding is continuously performed with a straight welding line. For example, Patent Document 1 discloses a method for manufacturing a laser welded structure and a laser welded structure in which plate-like members are stacked and continuously irradiated with a laser beam while moving the laser beam from the out-of-plane direction to join them. The welded plate-like members are bent at an angle θ in the plate thickness direction due to thermal shrinkage by laser welding, and a corner fold line appears on the outer plate-like member. The corner fold line can be made less visible by polishing the outer plate-like member in the direction along the corner fold line on the surface of the outer plate-like member.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] When plate-like members are stacked and continuously laser welded, distortion occurs in which they are bent at an angle θ in the plate thickness direction. However, when continuous laser welding is performed over a longer distance, distortion in the plate width direction may affect the quality of the product, and it may not be possible to perform laser welding properly.
[0005] An object of the present invention is to provide a method for manufacturing a laser welded structure and a laser welded structure with reduced distortion in the plate width direction.
Means for Solving the Problems
[0006] The present invention provides a method for manufacturing a laser-welded structure, comprising: a width stiffness analysis step for analyzing the width stiffness of a plate-shaped member formed in a long shape against load in the short direction; a welding line determination step for determining a welding line based on the analysis results of the width stiffness analysis step; and a laser welding step for joining the plate-shaped member and the joining plate portion of a mating member having a long plate-shaped joining plate portion that is long in the longitudinal direction of the plate-shaped member, by continuously laser welding them along the longitudinal direction based on the welding line determined in the welding line determination step.
[0007] The laser-welded structure of the present invention comprises a plate-shaped member formed in an elongated shape, and a mating member having an elongated plate-shaped joining plate portion that is laser-welded to the plate-shaped member and is long in the longitudinal direction of the plate-shaped member, wherein the welding line of the laser welding is formed in a straight line along the longitudinal direction, and the position of the plate-shaped member in the short direction on the welding line is based on a position where the rigidity of each divided member against load in the short direction is equal when the plate-shaped member is divided into two divided members by a straight line parallel to the welding line.
[0008] The laser-welded structure of the present invention comprises a plate-shaped member formed in an elongated shape, and a mating member having an elongated plate-shaped joining plate portion that is laser-welded to the plate-shaped member and is long in the longitudinal direction of the plate-shaped member. The welding lines of the laser welding are formed in a straight line along the longitudinal direction, and the positions of the plate-shaped member in the short direction at the two outermost welding lines of the plate-shaped member are based on positions where the rigidity of the two outermost divided members against load in the short direction is equivalent when the plate-shaped member is divided into a plurality of divided members by a straight line parallel to the welding lines. [Effects of the Invention]
[0009] According to the present invention, it is possible to provide a method for manufacturing a laser-welded structure with reduced distortion in the plate width direction, and a laser-welded structure. [Brief explanation of the drawing]
[0010] [Figure 1] Figure 1 is a flowchart showing the steps of the manufacturing method for a laser-welded structure. [Figure 2] Figure 2 is a perspective view showing a laser-welded structure including a long rectangular plate-like member. [Figure 3] Figure 3 is a partially enlarged perspective view of section P1 in Figure 1. [Figure 4] Figure 4 is a diagram illustrating the width stiffness analysis process, which analyzes the width stiffness of a plate-like member that has been divided at a tack welding line. It is an explanatory diagram showing the plate-like member viewed from the longitudinal direction. [Figure 5] Figure 5 is a plan view of a comparative example of a laser-welded structure showing a plate-shaped member formed with the welding line positioned outwards. [Figure 6] Figure 6 is a plan view of a comparative example of a laser-welded structure, showing how distortion (warping) occurs in a plate-shaped member when the welding line is formed towards the outside. [Figure 7] Figure 7 is a perspective view showing a laser-welded structure including a plate-shaped member having a bent portion. [Figure 8] Figure 8 is a partially enlarged perspective view of section P2 in Figure 7. [Figure 9] Figure 9 is a diagram illustrating the width stiffness analysis process, which analyzes the width stiffness of a plate-like member that has been divided at a tack welding line. It is an explanatory diagram showing the plate-like member viewed from the longitudinal direction. [Figure 10] Figure 10 is a perspective view showing a laser-welded structure including a plate-shaped member having a weld bead. [Figure 11] Figure 11 is a plan view showing a laser-welded structure including a plate-shaped member having a weld bead. [Figure 12] Figure 12 is a partially enlarged perspective view of section P3 in Figure 10. [Figure 13] Figure 13 is a diagram illustrating the width stiffness analysis process, which analyzes the width stiffness of a plate-like member that has been divided at a tack welding line. It is an explanatory diagram showing the plate-like member viewed from the longitudinal direction. [Figure 14] Figure 14 is a perspective view showing a laser-welded structure including a curved plate-like member. [Figure 15]FIG. 15 is a partially enlarged perspective view of a portion P4 in FIG. 14. [Figure 16] FIG. 16 is a plan view showing a laser welding structure including a rectangular plate-like member and having two formed welding lines. [Figure 17] FIG. 17 is a diagram for explaining a width rigidity analysis step of analyzing width rigidity assuming that a plate-like member is divided by a temporary welding line, and is an explanatory view of the plate-like member seen from the longitudinal direction.
Embodiments for Carrying Out the Invention
[0011] Hereinafter, embodiments according to the present invention will be described in detail based on the drawings. Note that the present invention is not limited by this embodiment. Also, the constituent elements in the following embodiments include those that can be replaced by those skilled in the art and are easy to replace, or those that are substantially the same.
[0012] As shown in FIG. 1, the method for manufacturing a laser welding structure according to this embodiment determines a welding line based on rigidity and performs laser welding, and includes a width rigidity analysis step (step S10), a welding line determination step (step S20), and a laser welding step (step S30). Here, the laser welding structure is obtained by continuously laser-welding and joining a plate-like member formed in a long shape and a joining plate portion of a joining partner member having a long plate-like joining plate portion in the longitudinal direction of the plate-like member along the longitudinal direction. Specifically, they are the laser welding structures 10, 20, 30, 40, 50 shown in FIGS. 2, 7, 10, 14, and 16. Details of each laser welding structure 10, 20, 30, 40, 50 will be described later. First, each step in the method for manufacturing a laser welding structure will be described below.
[0013] Width Rigidity Analysis Step (Step S10); In the width rigidity analysis step (Step S10), the width rigidity, which is the rigidity against the load in the short side direction (plate width direction) of the plate-shaped member formed in a long shape, is analyzed. More specifically, in the width rigidity analysis step (Step S10), for example, first, a linear temporary welding line along the longitudinal direction is set for the plate-shaped member. Then, when the plate-shaped member is divided into two divided members by the temporary welding line, the position of the temporary welding line where the width rigidity in each divided member is equal, that is, the position in the short side direction of the plate-shaped member on the temporary welding line is specified as the analysis result.
[0014] Welding Line Determination Step (Step S20); The welding line determination step (Step S20) determines the welding line based on the analysis result of the width rigidity analysis step (Step S10). More specifically, the welding line determination step (Step S20) determines the welding line based on the temporary welding line specified in the width rigidity analysis step (Step S10). The welding line may be the position of the temporary welding line as it is. However, for example, in the plate-shaped member, when there are portions such as holes or cutouts where laser welding cannot be performed linearly, the welding line can be set at a position close to the specified temporary welding line and avoiding the portions where laser welding such as holes or cutouts cannot be performed.
[0015] Laser Welding Step (Step S30); The laser welding step (Step S30) laser-welds and joins the joint plate portion of the joint partner member and the plate-shaped member based on the welding line determined by the welding line determination step (Step S20). This laser welding is continuously performed along the longitudinal direction of the plate-shaped member. The laser welding based on the welding line can be performed by tracing the determined welding line, but for example, depending on the actual state of the laser welding machine such as the table of the laser welding machine to which the welding target is attached, the determined welding line may be modified.
[0016] Furthermore, laser welding based on the welding line may be performed from either the plate-shaped member side or the mating member (joining plate portion) side. The strength of the laser welding can be set to a strength sufficient to penetrate only the plate on the side to which the laser beam is irradiated, out of the two plates (plate-shaped member and joining plate portion). Alternatively, the strength of the laser welding can be set to a strength sufficient to penetrate both plates (plate-shaped member and joining plate portion).
[0017] Furthermore, the width stiffness analysis step (step S10) and the welding line determination step (step S20) can also be implemented using computer processing. Alternatively, each step can be processed by drawing or other methods without using a computer. In addition, the width stiffness analysis in the width stiffness analysis step (step S10) may be performed using a method other than the method described above, which involves setting a temporary welding line and analyzing the width stiffness of the divided members. For example, the welding line may be determined by analyzing the stress distribution when a predetermined load is applied to the entire plate-shaped member in the short-side direction using computer simulation. Alternatively, the welding line may be determined by performing various tests on the actual plate-shaped member to analyze the width stiffness.
[0018] Next, a laser-welded structure 10 manufactured by a laser welding method will be described based on Figures 2 to 4. As shown in Figures 2 and 3, the laser-welded structure 10 has a plate-shaped member 11 made of a steel plate material formed into a long rectangle, and a mating member 12 made of a steel plate material that is joined to the plate-shaped member 11. The mating member 12 has a long plate-shaped joining plate portion 12a that is long in the longitudinal direction of the plate-shaped member 11. In the case of the mating member 12, the entire mating member 12 is the joining plate portion 12a. Also, the mating member 12 has the same shape as the plate-shaped member 11. The thickness of each plate of the plate-shaped member 11 and the mating member 12 is the same. For example, the thickness of the plate-shaped member 11 and the mating member 12 (joining plate portion 12a) can be 1 mm. In this case, the length in the longitudinal direction of the plate-shaped member 11 and the mating member 12 (joining plate portion 12a) can be 1200 mm. Furthermore, the length of the plate-shaped member 11 and the mating member 12 (joining plate portion 12a) in the shorter direction can be 65 mm.
[0019] The laser-welded structure 10 is continuously laser-welded along the welding line WL. Specifically, the laser-welded structure 10 is continuously laser-welded along the welding line WL. The welding line WL is formed in a long, straight line along the longitudinal direction of the plate-shaped member 11. The length of the welding line WL is continuously set to be approximately the same length as the longitudinal dimension of the plate-shaped member 11. The position of the welding line WL in the short direction of the plate-shaped member 11 is located approximately in the center of the short direction of the plate-shaped member 11 (i.e., the width direction of the plate-shaped member 11).
[0020] The position of the welding line WL in the short-side direction of the plate-shaped member 11 is determined in the welding line determination step (step S20) based on the analysis results of the width stiffness analysis step (step S10) in the manufacturing method of the laser-welded structure. Specifically, in the width stiffness analysis step (step S10), a temporary welding line VL is first set at an arbitrary position in the short-side direction of the plate-shaped member 11. The temporary welding line VL is a straight line along the longitudinal direction of the plate-shaped member 11 and is a temporary line for analyzing the width stiffness. The temporary welding line VL is a straight line parallel to the welding line WL that is determined in the welding line determination step (step S20), which is a step that follows the width stiffness analysis step (step S10).
[0021] After setting the temporary welding line VL, the plate-shaped member 11 is divided into two divided members 11-1 and 11-2 by the temporary welding line VL, as shown in Figure 4. The division of the plate-shaped member 11 into two divided members 11-1 and 11-2 can be processed by computer simulation or the like. Alternatively, the division of the plate-shaped member 11 into two divided members 11-1 and 11-2 can be done by drawing a diagram or by cutting the actual plate-shaped member 11.
[0022] After dividing the plate-shaped member 11 into two divided members 11-1 and 11-2, the width stiffness analysis step (step S10) analyzes the width stiffness, which is the stiffness (bending stiffness) of the plate-shaped member 11 against a load S in the short direction. The width stiffness analysis is performed by comparing the width stiffness of each divided member 11-1 and 11-2. For example, the width stiffness of divided member 11-1 can be the stiffness of the plate-shaped member 11 against a load S1 in the short direction in divided member 11-1. Similarly, the width stiffness of divided member 11-2 can be the stiffness of the plate-shaped member 11 against a load S2 in the short direction in divided member 11-2. For example, the width stiffness analysis can be performed based on the second moment of area of each divided member 11-1 and 11-2. Alternatively, the width stiffness analysis can be performed based on the cross-sectional area and section modulus of the cross-section of the divided members 11-1 and 11-2 in the short direction.
[0023] Then, in the width stiffness analysis step (step S10), the position of the temporary welding line VL in the short direction of the plate-shaped member 11 is identified such that the width stiffness of each divided member 11-1, 11-2 is equivalent. For example, as shown in Figure 3, the temporary welding line VL can be located approximately in the center of the short direction of the plate-shaped member 11. In a plate-shaped member 11 that is elongated rectangular and has a uniform cross-section in the longitudinal direction, the width stiffness of each divided member 11-1, 11-2, which is divided at approximately the center of the short direction, will be equivalent. Therefore, the temporary welding line VL is identified to be located approximately in the center of the short direction of the plate-shaped member 11.
[0024] The welding line determination step (step S20) determines the welding line WL based on the tack weld line VL identified in the width-stiffness analysis step (step S10). Here, based on the tack weld line VL identified as being approximately in the center of the short-side direction of the plate-shaped member 11, the same position as the identified tack weld line VL (i.e., the tack weld line VL itself) is determined as the welding line WL. Therefore, the welding line WL is located approximately in the center of the short-side direction of the plate-shaped member 11.
[0025] In this way, the position of the plate-shaped member 11 in the short-side direction on the welding line WL of the laser-welded structure 10 manufactured by the laser-welded structure manufacturing method is based on the position (approximately the center position in the short-side direction in the laser-welded structure 10) where the width rigidity of each divided member 11-1 and 11-2 is equivalent when the plate-shaped member 11 is divided into two divided members 11-1 and 11-2 by a straight line (tack welding line VL) parallel to the welding line WL. As a result, the laser-welded structure 10 manufactured by the laser-welded structure manufacturing method can have reduced distortion in the short-side direction (plate width direction) of the plate-shaped member 11 compared to the elongated rectangular plate-shaped member 11.
[0026] For example, the laser-welded structure 10A shown in Figure 5 as a comparative example is formed by laser welding a plate-shaped member 11 and a mating member 12 using a welding line WLa, similar to the laser-welded structures 10 in Figures 1 and 2. Here, the position of the plate-shaped member 11 in the short-side direction on the welding line WLa is set to be located towards one side of the plate-shaped member 11 in the short-side direction.
[0027] Laser welding can result in shrinkage of the welded area after welding. In the laser-welded structure 10A, the welded area, laser-welded based on the welding line WLa, shrinks along the welding line WLa, as indicated by arrows D1 and D2. Here, the width stiffness of one side of the plate-shaped member 11 in the short direction relative to the welding line WLa (the area 11h enclosed by the dashed line in Figure 5) is smaller than the width stiffness of the other side of the plate-shaped member 11 in the short direction relative to the welding line WLa (the area 11m enclosed by the dashed line in Figure 5). Therefore, the area 11h of the plate-shaped member 11 shrinks more than the area 11m of the plate-shaped member 11. Furthermore, since the welding line WLa side of area 11h is connected to area 11m, the shrinkage is restricted in area 11m. Consequently, the outer edge 11h1 of area 11h of the plate-shaped member 11 shrinks significantly. Then, the edge portion 11m1, which is the free end in region 11m of the plate-shaped member 11, is pulled by the contraction of region 11h and deforms to spread in the longitudinal direction of the plate-shaped member 11, as shown by arrows D3 and D4. As a result, the laser-welded structure 10A becomes distorted in the plate width direction (the short side direction of the plate-shaped member 11), as shown in Figure 6.
[0028] In particular, when laser welding thin steel plate materials with a thickness of about 1 mm to several mm, and plate-shaped members formed in a long shape with a longitudinal direction of 1000 mm or more, the laser welding is performed continuously in a substantially linear direction, which can result in significant distortion in the plate width direction (the short-side direction of the plate-shaped member 11). Therefore, in the manufacturing method of the laser-welded structure in this embodiment, the width stiffness of each divided member 11-1, 11-2 is analyzed when the plate-shaped member 11 is divided by a tack welding line VL, the position of the tack welding line VL where the width stiffness of each divided member 11-1, 11-2 is substantially equal is identified, the welding line WL is determined based on the identified tack welding line VL, and laser welding is performed based on the welding line WL. This balances the width stiffness between one side of the plate-shaped member 11 in the short-side direction relative to the welding line WL (corresponding to divided member 11-1) and the other side of the plate-shaped member 11 in the short-side direction relative to the welding line WL (corresponding to divided member 11-2). Therefore, in the laser-welded structure 10 according to this embodiment, the amount of distortion is substantially uniform between one portion of the plate-shaped member 11 in the short direction relative to the welding line WL (corresponding to the divided member 11-1) and the other portion of the plate-shaped member 11 in the short direction relative to the welding line WL (corresponding to the divided member 11-2). As a result, the overall distortion in the plate width direction of the laser-welded structure 10 is significantly reduced compared to the laser-welded structure 10A.
[0029] Furthermore, in the width stiffness analysis step (step S10), we decided to analyze the width stiffness, that is, the stiffness of the plate-shaped member 11 against a load S in the short direction. The reason for this is as follows: When the laser-welded joint, which is long in the longitudinal direction of the plate-shaped member 11, shrinks, a force acts on the plate-shaped member 11 along the longitudinal direction of the weld (arrows D1 and D2 in Figure 5). For example, if we focus on the upper cross section in the short direction of the plate-shaped member 11, such as the divided member 11-1, this cross section is subjected to a force that pulls it downwards (towards the weld) due to the shrinkage force of the weld (force in the direction of arrows D1 and D2). When this force was considered as a load S in the short-side direction of the plate-shaped member 11 (i.e., a bending load along the plate width direction (short-side direction) of the plate-shaped member 11), and the second moment of area, etc., in the cross-section in the short-side direction of the plate-shaped member 11 was examined, it was found that the cross-section (second moment of area, etc.) in the short-side direction of the plate-shaped member 11 influences the deformation of the plate-shaped member 11 caused by the shrinkage of the welded joint during laser welding. In this way, by analyzing the width stiffness and setting an appropriate welding line WL, it was possible to suppress the deformation caused by the shrinkage of laser welding.
[0030] Next, the laser-welded structure 20 will be described based on Figures 7 to 9. As shown in Figures 7 and 8, the laser-welded structure 20 has a plate-shaped member 21 and a mating member 22. The plate-shaped member 21 is formed in an elongated shape and has a bent portion 25 along its longitudinal direction. The bent portion 25 provided along the longitudinal direction is a bent portion that is bent at a right angle. In other words, the plate-shaped member 21 is formed in a substantially L-shape when viewed from the longitudinal direction. The cross-section of the plate-shaped member 21 in the short direction is uniform. One side of the plate-shaped member 21 with respect to the bent portion 25 is the joining target plate portion 21a, which is the part that is joined to the mating member 22 by laser welding. The other side of the plate-shaped member 21 with respect to the bent portion 25 is the non-joining target plate portion 21b, which is the part that is not joined to the mating member 22.
[0031] The mating member 22 has a long, plate-shaped joining plate portion 22a that is elongated in the longitudinal direction of the plate-shaped member 21. In the laser-welded structure 20, the entire mating member 22 is the joining plate portion 22a. The joining plate portion 22a (matting member 22) is formed to be substantially the same shape as the plate-shaped member 21's target plate portion 21a.
[0032] In the laser-welded structure 20, the welding line WL is positioned near the bent portion 25. The welding line WL can be set by performing a width stiffness analysis step (step S10) and a welding line determination step (step S20). Specifically, the width stiffness analysis step (step S10) sets a linear temporary welding line VL along the longitudinal direction of the plate portion 21a of the plate-shaped member 21 at an arbitrary position in the short direction of the plate portion 21a to be joined. Then, as shown in Figure 9, the plate-shaped member 21 is divided into two divided members 21-1 and 21-2 by the temporary welding line VL. Furthermore, the width stiffness analysis step (step S10) identifies the position in the short direction of the plate portion 21a to be joined at the temporary welding line VL where the width stiffness of the divided member 21-1 and the divided member 21-2 are equivalent, and obtains the width stiffness analysis result.
[0033] Specifically, the analysis of the width stiffness of the plate-shaped member 21 is performed by comparing the width stiffness of the respective divided members 21-1 and 21-2. For example, the width stiffness of divided member 21-1 can be the stiffness of the plate portion 21a of the plate-shaped member 21 to be joined with respect to a load S1 in the short direction. Similarly, the width stiffness of divided member 21-2 can be the stiffness of the plate portion 21a of the plate-shaped member 21 to be joined with respect to a load S2 in the short direction.
[0034] Generally, when a bent section (bend) is provided along the longitudinal direction, the rigidity of the bent section increases. Therefore, in the laser-welded structure 20, by setting the welding line WL to a position closer to the bent section 25 (in other words, a position closer to the bent section 25 than the central position CL of the plate portion 21a of the plate-shaped member 21 to be joined, which is the part to be joined (see Figures 7 and 8)), the width rigidity of the divided member 21-1 and the divided member 21-2 shown in Figure 9 becomes approximately the same. In this way, the distortion in the width direction of the plate-shaped member 21 (plate portion 21a to be joined) is reduced in the laser-welded structure 20.
[0035] In this way, the position of the plate-shaped member 21 (plate portion 21a to be joined) in the short-side direction on the welding line WL of the laser-welded structure 20 manufactured by the laser-welded structure manufacturing method is based on a position where the width rigidity of the divided members 21-1 and 21-2 are equivalent when the plate-shaped member 21 is divided into two divided members 21-1 and 21-2 by a straight line parallel to the welding line WL (temporary welding line VL) (specifically, a position closer to the bent portion 25 than the approximate center position CL in the short-side direction of the plate portion 21a to be joined on the plate-shaped member 21). As a result, the laser-welded structure 20 manufactured by the laser-welded structure manufacturing method can reduce the distortion in the short-side direction (plate width direction) of the plate portion 21a to be joined on the plate-shaped member 21, compared to a plate-shaped member 21 that is formed in an elongated shape and has an approximately L-shaped cross-section.
[0036] Next, the laser-welded structure 30 will be described based on Figures 10 to 13. As shown in Figures 10 to 12, the laser-welded structure 30 has a plate-shaped member 31 and a mating member 32. The plate-shaped member 31 is formed in an elongated shape, and a bead portion 35 is provided along its longitudinal direction. The bead portion 35 is a bent portion formed in a semicircular shape when viewed from the longitudinal direction, so as to protrude in the thickness direction of the plate-shaped member 31 on the side opposite to the side on which the mating member 32 is provided.
[0037] The mating member 32 has a long, plate-shaped joining plate portion 32a that is elongated in the longitudinal direction of the plate-shaped member 31. In the laser-welded structure 30, the entire mating member 32 is the joining plate portion 32a.
[0038] In the laser-welded structure 30, the welding line WL is positioned close to the bead portion 35. The welding line WL can be set by performing a width stiffness analysis process (step S10). Specifically, the width stiffness analysis process (step S10) sets a linear temporary welding line VL along the longitudinal direction of the plate-shaped member 31 at an arbitrary position in the short direction of the plate-shaped member 31. Then, as shown in Figure 13, the plate-shaped member 31 is divided into two divided members 31-1 and 31-2 by the temporary welding line VL. Furthermore, the width stiffness analysis process (step S10) identifies the position in the short direction of the plate-shaped member 31 at the temporary welding line VL where the width stiffness of divided members 31-1 and 31-2 are equivalent, and obtains the width stiffness analysis result.
[0039] Specifically, the analysis of width stiffness is performed by comparing the width stiffness of each divided member 31-1 and 31-2. For example, the width stiffness of divided member 31-1 can be defined as the stiffness of the plate-shaped member 31 in divided member 31-1 against a load S1 in the short direction. Similarly, the width stiffness of divided member 31-2 can be defined as the stiffness of the plate-shaped member 31 in divided member 31-2 against a load S2 in the short direction.
[0040] In the laser-welded structure 30, the welding line WL is set to a position close to the bead portion 35, which is a bent portion. In other words, the welding line WL is set to a position closer to the bead portion 35 than the central position CL in the short direction of the plate-shaped member 31, which is the part to which the joining plate portion 32a is joined (see Figure 10). As a result, the width rigidity of the divided member 31-1 and the divided member 31-2 shown in Figure 13 becomes approximately the same, and the distortion in the plate width direction of the laser-welded structure 30 is reduced.
[0041] In this way, the position of the plate-shaped member 31 in the short-side direction on the welding line WL of the laser-welded structure 30 manufactured by the laser-welded structure manufacturing method is based on a position where the width rigidity of the divided members 31-1 and 31-2 are equivalent when the plate-shaped member 31 is divided into two divided members 31-1 and 31-2 by a straight line parallel to the welding line WL (temporary welding line VL) (specifically, a position closer to the bead portion 35 than the approximate center position CL in the short-side direction of the plate-shaped member 31). As a result, the laser-welded structure 30 manufactured by the laser-welded structure manufacturing method can reduce the distortion in the short-side direction (plate width direction) of the plate-shaped member 31 compared to the plate-shaped member 31 which is formed in a long rectangular plate shape with a bead portion 35.
[0042] In other words, in plate-shaped members 21 and 31 having bent portions such as the bent portion 25 (see Figure 8) and the bead portion 35 (see Figure 12), the welding line WL is located on the bent portion side of the central position CL in the short direction of the plate-shaped member 21 (the plate portion to be joined 21a) and the plate-shaped member 31 in the portion where the joining plate portions 22a and 32a of the plate-shaped members 21 and 31 are joined (specifically, the plate portion to be joined 21a in the case of plate-shaped member 21, and the entire plate-shaped member 31 in the case of plate-shaped member 31). As a result, even in plate-shaped members 21 and 31 with bent portions, it is possible to create laser-welded structures 20 and 30 that reduce distortion in the short direction (plate width direction) of the plate-shaped members 21 and 31.
[0043] Next, the laser-welded structure 40 will be described based on Figures 14 and 15. As shown in Figures 14 and 15, the laser-welded structure 40 has a plate-shaped member 41 and a mating member 42. The plate-shaped member 41 is formed in a substantially rectangular shape, and its longitudinal direction is curved in a direction perpendicular to the longitudinal and transverse directions. On the other hand, the mating member 42 is entirely a joining plate portion 42a that is joined to the plate-shaped member 41. The mating member 42 (joining plate portion 42a) is curved with a curvature equivalent to that of the plate-shaped member 41. The length (plate width) of the mating member 42 in the transverse direction is shorter (narrower) than the length (plate width) of the plate-shaped member 41 in the transverse direction.
[0044] In the laser-welded structure 40, the welding line WL is set at approximately the center of the plate-shaped member 41 in the short-side direction. That is, the position of the plate-shaped member 41 in the short-side direction along the welding line WL is the same as in the laser-welded structure 10 (see Figure 1) described above, where the width rigidity of the two divided members, which are divided at approximately the center of the plate-shaped member 41 in the short-side direction, is considered to be equal.
[0045] In this way, the position of the plate-shaped member 41 in the short-side direction in the welding line WL of the laser-welded structure 40 manufactured by the laser-welded structure manufacturing method is based on a position where the width rigidity of each divided member is equal when the plate-shaped member 41 is divided into two divided members by a straight line parallel to the welding line WL (specifically, the approximate center position in the short-side direction of the plate-shaped member 41). As a result, the laser-welded structure 40 manufactured by the laser-welded structure manufacturing method can reduce the distortion in the short-side direction (plate width direction) of the plate-shaped member 41, which is rectangular in shape and whose longitudinal direction is curved in a direction perpendicular to the longitudinal and short-side directions.
[0046] The laser-welded structures 10, 20, 30, and 40 described above comprise elongated plate-shaped members 11, 21, 31, and 41, and joining partners 12, 22, 32, and 42 having elongated plate-shaped joining plate portions 12a, 22a, 32a, and 42a that are laser-welded to the plate-shaped members 11, 21, 31, and 41, and the welding line WL for laser welding is formed linearly along the longitudinal direction of the plate-shaped members 11, 21, 31, and 41, and the plate-shaped members 11 in the welding line WL The positions of 21, 31, and 41 in the short-side direction are based on the position where the rigidity of the plate-like members 11, 21, 31, and 41 against loads in the short-side direction is equivalent in the divided members 11-1, 21-1, 31-1, etc. and divided members 11-2, 21-2, 31-2, etc., when the plate-like members 11, 21, 31, and 41 are divided into two parts, such as divided members 11-1, 21-1, 31-1, etc. and divided members 11-2, 21-2, 31-2, etc., by a straight line parallel to the welding line WL (for example, a tack welding line VL).
[0047] As a result, laser-welded structures 10, 20, 30, and 40, in which the joining plate portions 12a, 22a, 32a, and 42a of the mating members 12, 22, 32, and 42 are joined to plate-shaped members 11, 21, 31, and 41 for purposes such as reinforcement, can be made to have reduced distortion in the short-side direction of the plate-shaped members 11, 21, 31, and 41 (the plate width direction, or more precisely, the direction perpendicular to the welding line WL along the plate surface of the plate-shaped members 11, 21, 31, and 41).
[0048] Generally, when two plate-shaped members are joined by welding such as laser welding, the joined welded structure will warp in the thickness direction of the plates, and countermeasures are taken to address this. However, when two long, relatively thin plate-shaped members are joined by laser welding, the laser welding is performed continuously in a straight line, and as the length of the welded section increases, the effect of shrinkage due to laser welding becomes more pronounced, resulting in distortion (warping) in the width direction of the plates in the joined laser-welded structure. Therefore, according to the manufacturing method of the laser-welded structure of this embodiment, even in a laser-welded structure in which two plate-shaped members are joined continuously along the longitudinal direction by laser welding, the distortion (warping) in the width direction of the laser-welded structure is reduced, and proper laser welding can be performed.
[0049] Next, the laser-welded structure 50 will be described based on Figures 16 and 17. As shown in Figure 16, the laser-welded structure 50 has a plate-shaped member 51 and a mating member 52. The plate-shaped member 51 is formed in a long rectangular shape. The mating member 52 is a plate-shaped member with the same shape as the plate-shaped member 51. In the laser-welded structure 50, the entire mating member 52 is considered to be the joining plate portion 52a. The configuration of the plate-shaped member 51 and the mating member 52 is the same as that of the laser-welded structure 10 (see Figure 2).
[0050] In the laser-welded structure 50, two welding lines WL are provided along the longitudinal direction of the plate-shaped member 51. The welding lines WL can be set by performing a width stiffness analysis process (step S10). Specifically, the width stiffness analysis process (step S10) sets two linear tack weld lines VL along the longitudinal direction of the plate-shaped member 51 at arbitrary positions in the short direction of the plate-shaped member 51. Then, as shown in Figure 17, the plate-shaped member 21 is divided into three divided members 51-1, 51-2, and 51-3 by the tack weld lines VL. Furthermore, the width stiffness analysis process (step S10) identifies the position in the short direction of the plate-shaped member 51 in the two tack weld lines VL that form the two outer divided members 51-1 and 51-2, such that the width stiffness of the two outer divided members 51-1 and 51-2 are equivalent, and obtains the width stiffness analysis result. Specifically, the analysis of width stiffness is performed by comparing the width stiffness of each divided member 51-1 and 51-2. For example, the width stiffness of divided member 51-1 can be defined as the stiffness of the plate-shaped member 51 in divided member 51-1 against a load S1 in the short direction. Similarly, the width stiffness of divided member 51-2 can be defined as the stiffness of the plate-shaped member 51 in divided member 51-2 against a load S2 in the short direction.
[0051] In other words, when setting at least two welding lines WL, the position in the short direction of the temporary welding line VL where the width stiffness of the two outer divided members 51-1 and 51-2 is equivalent can be identified and used as the width stiffness analysis result. This balances the strain in the parts of the plate-shaped member 51 corresponding to the two outer divided members 51-1 and 51-2, thereby reducing the overall strain in the laser-welded structure 50.
[0052] In this way, the position of the plate-shaped member 51 in the short-side direction on the two outer welding lines WL of the laser-welded structure 50 manufactured by the laser-welded structure manufacturing method is based on a position where the width rigidity of the two outer divided members 51-1 and 51-2 is equivalent when the plate-shaped member 51 is divided into multiple divided members 51-1, 51-2, and 51-3 by a straight line parallel to the welding line WL (for example, a tack welding line VL). As a result, even when the laser-welded structure 50 manufactured by the laser-welded structure manufacturing method is formed by joining a long rectangular plate-shaped member 51 and a mating member 52 using multiple welding lines WL, the distortion of the plate-shaped member 51 in the short-side direction (plate width direction) can be reduced.
[0053] In the laser-welded structure 50, two welding lines WL were formed, but it is also possible to form three or more welding lines WL. In this case as well, in the width stiffness analysis step (step S10), the divided members to be analyzed should be those two outer tack weld lines VL that result in the two outer divided members having equivalent width stiffness, and these two tack weld lines VL should be identified and used as the analysis result. Then, in the welding line determination step (step S20), two welding lines WL should be determined based on this analysis result, that is, based on the two identified tack weld lines VL.
[0054] Therefore, in the above method for manufacturing a laser-welded structure, the width stiffness analysis step (step S10) involves setting at least two linear tack weld lines VL along the longitudinal direction of the plate-shaped member 51, dividing the plate-shaped member 51 into multiple divided members 51-1, 51-2, and 51-3 by the multiple tack weld lines VL. The analysis results identify the positions of the plate-shaped member 51 in the short direction at the two tack weld lines VL that form the two outer divided members 51-1 and 51-2, which have equivalent width stiffness. The welding line determination step (step S20) determines two welding lines WL based on the two tack weld lines VL identified in the width stiffness analysis step (step S10).
[0055] Furthermore, the laser-welded structure 50 comprises a plate-shaped member 51 formed in an elongated shape, and a mating member 52 having an elongated plate-shaped joining plate portion 52a that is laser-welded to the plate-shaped member 51 and is long in the longitudinal direction of the plate-shaped member 51. Two of the multiple laser welding lines WL are formed linearly along the longitudinal direction of the plate-shaped member 51, and the positions in the short-side direction of the two outer plate-shaped members 51 of the two welding lines WL are based on positions where the rigidity of the plate-shaped member 51 against load in the short-side direction is equivalent in the two outer divided members 51-1, 51-2, and 51-3 when the plate-shaped member 51 is divided into multiple divided members 51-1, 51-2, and 51-3 by a straight line parallel to the welding line WL (for example, a tack welding line VL). As a result, even in a laser-welded structure 50 joined by multiple welding lines WL, distortion in the plate width direction can be reduced.
[0056] As stated above, the present invention is not limited to these embodiments and can be implemented in various forms. In the above embodiments, the mating members 12, 22, 32, 42, and 52 are assumed to be entirely composed of joining plate portions 12a, 22a, 32a, 42a, and 52a. However, for example, the mating member can be a member with a substantially L-shaped cross-section, and may have a configuration other than the joining plate portion. Furthermore, the mating member may have a projection that protrudes from the edge of the joining plate portion, having a plate surface continuous with the joining plate portion, and this projection may have a hole. Moreover, the mating member may have a cross-section that is not uniform in the short direction.
[0057] Furthermore, although the plate-like members 11, 21, 31, 41, and 51 are assumed to have a uniform cross-section in the short-side direction, plate-like members with a non-uniform cross-section in the short-side direction can also be used. In this case, minute holes, etc., can be ignored in the analysis of width stiffness. Alternatively, the width stiffness of plate-like members with a non-uniform cross-section in the short-side direction can be analyzed by setting a temporary welding line VL by approximating the plate-like member's cross-section in the short-side direction to be uniform, and then analyzing the width stiffness. Alternatively, the shape of these plate-like members can be considered in the process of setting a temporary welding line VL and determining the welding line WL based on the identified temporary welding line VL. [Explanation of Symbols]
[0058] 10, 10A, 20, 30, 40, 50: Laser-welded structures 11,21,31,41,51: Plate-shaped members 11-1, 11-2, 21-1, 21-2, 31-1, 31-2, 51-1, 51-2, 51-3: Divided members 12, 22, 32, 42, 52: Joining mating members 12a, 22a, 32a, 42a, 52a: Joint plate part 25: Folding part 35: Bead section CL: Center position VL: Temporary welding line WL: Welding line
Claims
1. A width stiffness analysis process for analyzing the width stiffness, which is the stiffness of a plate-like member formed in a long shape against loads in the short direction, A welding line determination step in which the welding line is determined based on the analysis results of the width stiffness analysis step, A laser welding step is performed to join the plate-shaped member and the joining plate portion of a joining mating member having a long plate-shaped joining plate portion that is long in the longitudinal direction of the plate-shaped member, by overlapping them and continuously laser welding them along the longitudinal direction, based on the welding line determined in the welding line determination step. Equipped with, The width stiffness analysis step involves setting a linear tack weld line along the longitudinal direction of the plate-shaped member, dividing the plate-shaped member into two divided members by the tack weld line, and identifying the position in the short direction of the tack weld line where the width stiffness of each divided member is equivalent, thereby obtaining the analysis result. The welding line determination step determines the welding line based on the tack weld line identified in the width-stiffness analysis step. A method for manufacturing laser-welded structures.
2. The plate-like member is formed in an elongated rectangular shape, The welding line is located in the center of the plate-shaped member in the shorter direction. A method for manufacturing a laser-welded structure according to claim 1.
3. The plate-like member is formed in a curved shape such that its longitudinal direction curves in a direction perpendicular to the longitudinal direction and the short direction. The joining plate portion of the mating member is curved with a curvature equivalent to the curvature of the plate-shaped member. A method for manufacturing a laser-welded structure according to claim 2.
4. The plate-like member has a bent portion provided along the longitudinal direction, The welding line is located on the side of the bent portion rather than the central position in the short direction of the portion of the plate-shaped member to which the joining plate portion is joined. A method for manufacturing a laser-welded structure according to claim 1.
5. The aforementioned bent portion is a bent portion provided along the longitudinal direction and bent at a right angle. A method for manufacturing a laser-welded structure according to claim 4.
6. The bent portion is a bead portion provided along the longitudinal direction. A method for manufacturing a laser-welded structure according to claim 4.
7. A width stiffness analysis step for analyzing the width stiffness, which is the stiffness of a plate-shaped member formed in a long shape against a load in the short direction, A welding line determination step in which the welding line is determined based on the analysis results of the width stiffness analysis step, A laser welding step is performed to join the plate-shaped member and the joining plate portion of a joining mating member having a long plate-shaped joining plate portion that is long in the longitudinal direction of the plate-shaped member, by overlapping them and continuously laser welding them along the longitudinal direction, based on the welding line determined in the welding line determination step. Equipped with, The width stiffness analysis step involves setting at least two straight tack weld lines along the longitudinal direction of the plate-like member, dividing the plate-like member into multiple divided members by the multiple tack weld lines, and identifying the positions in the short direction of the two tack weld lines that form the two outer divided members, such that the width stiffness of the two outer divided members is equivalent, to obtain the analysis result. The welding line determination step determines two welding lines based on the two tack weld lines identified in the width-stiffness analysis step. A method for manufacturing laser-welded structures.