Manufacturing method for the vehicle body frame structure

Abstract

The present invention provides a method for manufacturing a vehicle body frame structure that joins three metal plates constituting the vehicle body with higher rigidity than conventional methods. [Solution] The manufacturing method for the vehicle body frame structure 10 includes a clamping step of overlapping the flange portions of the inner panel 20 and the stiffener 30 and clamping the flange portions with a plurality of clamp members C arranged at intervals from each other; a laser welding step of forming a plurality of laser-welded sections L of a predetermined length by performing continuous laser welding between adjacent clamp members C; a clamp release step of removing the clamp members C; and a spot welding step of overlapping an outer panel 40 made of galvanized steel sheet onto the outside of the inner panel 20 and stiffener 30 that have been laser-welded to each other, and forming a plurality of spot-welded sections S by spot-welding the flange portions of the inner panel 20, stiffener 30 and outer panel 40 between adjacent laser-welded sections L.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a vehicle body frame structure.

Background Art

[0002] In recent years, research and development on weight reduction that contributes to energy efficiency has been carried out to ensure that more people can gain access to affordable, reliable, sustainable and advanced energy. Patent Document 1 discloses a technology in which a first vehicle body structural plate and a second vehicle body structural plate adjacent to the vehicle interior side of the first vehicle body structural plate are joined by spot welding, then a surface plate is arranged on the vehicle body surface side of the first vehicle body structural plate, laser welding is performed between adjacent spot welding marks, and the surface plate is joined to the vehicle body surface side of the first vehicle body structural plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, two inner metal plates such as hot-pressed materials that contribute to rigidity are joined by spot welding with adjacent welding points separated by a predetermined distance. If the metal plates contributing to rigidity can be seamlessly welded to each other, the rigidity is improved and further weight reduction becomes possible. In this respect, the technique described in Patent Document 1 has room for improvement.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a vehicle body frame structure that joins three metal plates constituting a vehicle body with higher rigidity than before. This in turn contributes to energy efficiency.

Means for Solving the Problems

[0006] To solve the aforementioned problems, the present invention provides a method for manufacturing a vehicle body frame structure, comprising stacking an inner panel, a stiffener, and an outer panel made of galvanized steel sheet in this order from the inside of the vehicle, and joining the flange portions provided on each of the inner panel, the stiffener, and the outer panel, comprising a clamping step in which the flange portions of the inner panel and the stiffener are stacked and clamped together with a plurality of clamp members arranged at intervals from each other, and adjacent clamp members The process includes: a laser welding step of joining the flange portions of the inner panel and the stiffener by performing continuous laser welding between them to form a plurality of laser-welded portions of a predetermined length; a clamp release step of removing the clamp member; and a spot welding step of overlapping the outer panel on the outside of the inner panel and the stiffener that have been laser-welded to each other, and spot welding the flange portions of the inner panel, stiffener and outer panel between adjacent laser-welded portions to form a plurality of spot-welded portions. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for manufacturing a vehicle body frame structure that joins three metal plates constituting the vehicle body with higher rigidity than conventional methods. This, in turn, contributes to energy efficiency. [Brief explanation of the drawing]

[0008] [Figure 1] This is an exploded perspective view showing three panels that constitute the vehicle body frame structure according to the embodiment. [Figure 2] This is a side view showing the inner panel and stiffener joined together. [Figure 3] This is a side view showing the inner panel, stiffener, and outer panel joined together. [Figure 4A]This is a side view showing the inner panel and stiffener fixed together with clamp members. [Figure 4B] Figure 4A is a cross-sectional view of the IVB-IVB line. [Figure 5] This is a side view showing the inner panel and stiffener after laser welding. [Figure 6A] This is a schematic perspective view showing the wobbling welding process and the resulting wobbling marks. [Figure 6B] This is a schematic cross-sectional view illustrating the wobbling welding process. [Figure 7] This is a side view showing the clamp member removed after laser welding. [Figure 8] This is a side view showing the Stifner with the outer panel installed on the outside of the vehicle. [Figure 9] This is a side view showing the inner panel, stiffener, and outer panel joined together by spot welding. [Figure 10] Figure 9 shows a cross-sectional view of the XX line. [Figure 11] Figure 9 shows a cross-sectional view of the line XI-XI. [Figure 12] This is a magnified view of the area near the lower end of the center pillar during the laser welding process. [Figure 13] This is a schematic side view of a movable clamp. [Modes for carrying out the invention]

[0009] The vehicle body frame structure according to this embodiment will be described in detail with reference to the drawings as appropriate. In this embodiment, the case in which the present invention is applied to the panels constituting the area around the door opening of the vehicle body will be described. When indicating direction in the description, the description will be based on the front, rear, left, right, up, and down directions shown in Figure 1.

[0010] As shown in Figure 1, the vehicle body frame structure 10 according to this embodiment constitutes the frame of the side of the vehicle body. The vehicle body frame structure 10 is constructed by joining a total of three panels, an inner panel 20, a stiffener 30, and an outer panel 40, in that order from the inside of the vehicle. As shown in Figure 3, the vehicle body frame structure 10 has a side sill 11 that extends front to rear at the bottom of the vehicle body, a roof rail 12 that extends front to rear at the top of the vehicle body, a front pillar 13 that connects the front ends of the side sill 11 and the roof rail 12, a center pillar 14 that connects the middle parts of the side sill 11 and the roof rail 12, and a rear pillar 15 that connects the rear ends of the side sill 11 and the roof rail 12. The side sill 11, roof rail 12, front pillar 13, center pillar 14, and rear pillar 15 are hollow structures formed by joining the three panels described above to each other (see Figure 10). Furthermore, the vehicle body frame structure 10 includes a front door opening 16F, which serves as an entrance and exit for the front passengers, and a rear door opening 16R, which serves as an entrance and exit for the rear passengers. Note that if there is no need to distinguish between the front door opening 16F and the rear door opening 16R, they may simply be referred to as the door opening 16.

[0011] As shown in Figure 1, the inner panel 20 is the structural member located furthest inside the vehicle among the three panels. The inner panel 20 is made of high-tensile strength steel plate (also called "high-tensile material"). The inner panel 20 has a side sill portion 21 that extends front to rear at the bottom of the vehicle body, a roof rail portion 22 that extends front to rear at the top of the vehicle body, a front pillar portion 23 that connects the front ends of the side sill portion 21 and the roof rail portion 22, a center pillar portion 24 that connects the middle parts of the side sill portion 21 and the roof rail portion 22, and a rear pillar portion 25 that connects the rear ends of the side sill portion 21 and the roof rail portion 22. In addition, the side sill portion 21, the roof rail portion 22, the front pillar portion 23, the center pillar portion 24, and the rear pillar portion 25 have an inner flange portion 20i that extends toward the door opening 16. The inner flange portion 20i is provided continuously so as to surround the perimeter of the door opening 16. In other words, the inner flange portion 20i is formed along the door opening. The side sill portion 21, roof rail portion 22, front pillar portion 23, and rear pillar portion 25 each have an outer flange portion 20o that extends away from the door opening 16. The outer flange portion 20o is provided along the outer edge of the inner panel 20.

[0012] As shown in Figure 1 and Figure 2, the stiffener 30 is a structural member disposed at the center among the three panels. The stiffener 30 is made of a high-tensile steel plate (also referred to as "high-tensile material") with high tensile strength. Like the inner panel 20, the stiffener 30 has a side sill portion 31, a roof rail portion 32, a front pillar portion 33, a center pillar portion 34, and a rear pillar portion 35. Further, the side sill portion 31, the roof rail portion 32, the front pillar portion 33, the center pillar portion 34 and the rear pillar portion 35 of the stiffener 30 each have an inner flange portion 30i extending toward the door opening 16. The inner flange portion 30i is provided continuously so as to surround the periphery of the door opening 16. In other words, the inner flange portion 30i is formed along the door opening. Further, the side sill portion 31, the roof rail portion 32, the front pillar portion 33 and the rear pillar portion 35 of the stiffener 30 each have an outer flange portion 30o extending to the side opposite to the door opening 16. The outer flange portion 30o is provided along the outer edge of the stiffener 30.

[0013] As shown in Figure 1 and Figure 3, the outer panel 40 is a structural member disposed at the outermost side among the three panels. The outer panel 40 also doubles as a design member (exterior material). The stiffener 30 is made of, for example, a galvanized steel sheet that is thinner and lower in strength than the high-tensile steel sheet. Like the inner panel 20 and the stiffener 30, the outer panel 40 has a side sill portion 41, a roof rail portion 42, a front pillar portion 43, a center pillar portion 44, and a rear pillar portion 45. Further, the side sill portion 41, the roof rail portion 42, the front pillar portion 43, the center pillar portion 44 and the rear pillar portion 45 of the outer panel 40 each have an inner flange portion 40i extending toward the door opening 16. The inner flange portion 40i is provided continuously so as to surround the periphery of the door opening 16. In other words, the inner flange portion 40i is formed along the door opening. Further, the side sill portion 41, the roof rail portion 42, the front pillar portion 43 and the rear pillar portion 45 of the outer panel 40 each have an outer flange portion 40o extending to the side opposite to the door opening 16. The outer flange portion 40o is provided along the outer edge of the outer panel 40.

[0014] The inner panel 20 and the stiffener 30 are formed into a panel shape (frame shape) by joining a plurality of long members made of a high-tensile steel plate pressed into a predetermined shape to each other in the longitudinal direction. On the other hand, the outer panel 40 is formed into an integral panel shape (frame shape) by subjecting a single large galvanized steel sheet to press working and punching working.

[0015] As shown in Figure 2, the inner panel 20 and the stiffener 30 are joined to each other at their inner flange portions 20i, 30i and outer flange portions 20o, 30o by laser welding. Reference sign L in Figure 2 denotes a laser weld portion L formed into a bead shape of a predetermined length by laser welding. The laser weld portions L of the inner flange portions 20i, 30i in the present embodiment are provided, for example, along the entire periphery of the front door opening 16F, and along the lower half portions of the side sill portions 21, 31, roof rail portions 22, 32, center pillar portions 24, 34, and rear pillar portions 25, 35 of the rear door opening 16R. Further, the laser weld portions L of the outer flange portions 20o, 30o are provided, for example, along the outer edges of the roof rail portions 22, 32. The laser welding of the inner panel 20 and the stiffener 30 will be described in detail later.

[0016] As shown in Figure 3, the inner panel 20, stiffener 30, and outer panel 40 are joined by spot welding between adjacent laser-welded sections L at the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o. In Figure 3, the symbol S represents a spot-welded section S formed in a nugget shape by spot welding. In this embodiment, the spot-welded sections S of the inner flange portions 20i, 30i, 40i are provided, for example, along the entire circumference of the front door opening 16F, and along the side sill portions 21, 31, 41, roof rail portions 22, 32, 42, center pillar portions 24, 34, 44, and the lower half of the rear pillar portions 25, 35, 45 of the rear door opening 16R. The spot-welded sections S of the outer flange portions 20o, 30o, 40o are provided, for example, along the outer edges of the roof rail portions 22, 32, 42. Here, as shown in Figure 3, the outer panel 40 is joined to the inner panel 20 and stiffener 30 only by spot welds S, and does not have laser welds L. The spot welding of the inner panel 20, stiffener 30 and outer panel 40 will be described in detail later.

[0017] Next, the manufacturing method of the vehicle body frame structure 10 according to this embodiment will be described with reference to Figures 4 to 11. For the sake of clarity, the following description of the manufacturing method and Figures 4 to 11 will use the roof rail sections 22, 32, 42 and the upper end portions of the center pillar sections 24, 34, 44, which are part of the vehicle body frame structure 10, as an example, but other parts are manufactured using the same method. The manufacturing method for the vehicle body frame structure 10 according to this embodiment includes a clamping step, a laser welding step, a clamp release step, and a spot welding step.

[0018] <Clamping process> As shown in Figures 4A and 4B, in the clamping process, the inner panel 20 and the stiffener 30 are overlapped, and their inner flange portions 20i and 30i are clamped together by clamping members C. The clamping members C are not limited in type as long as they can fix the overlapping plates, but for example, a hand vise, which is a type of toggle clamp, can be used. Multiple clamping members C are positioned in the areas where spot welding will be performed in the spot welding process, which will be described later. Multiple clamping members C are spaced apart from each other in the longitudinal direction. By clamping the inner flange portions 20i and 30i together with multiple clamping members C, the gap between the inner flange portions 20i and 30i is reduced to a predetermined value or less. The dashed lines drawn between adjacent clamping members C indicate the areas where laser welding will be performed. Also, in Figures 4A and 4B, the outer flange portions 20o and 30o are depicted as already joined by the laser welding section L.

[0019] <Laser welding process> Following the clamping process, a laser welding process is performed. As shown in Figure 5, in the laser welding process, continuous laser welding is performed between adjacent clamp members C. This forms multiple laser-welded sections L of a predetermined length along the periphery of the door opening 16, joining the inner flange sections 20i and 30i of the inner panel 20 and stiffener 30.

[0020] In this embodiment, laser welding is performed by so-called wobbling welding. As shown in Figure 6A, wobbling welding is a welding method that increases the amount of molten material in the width direction of the weld by manipulating the optical system that irradiates the laser to create a wobbling shape Lw. Wobbling welding can form a thicker weld bead compared to when the optical system is operated linearly. Also, as shown in Figure 6B, in wobbling welding, the weld bead (molten pool) is stirred and flowed by the laser. This suppresses the occurrence of blowholes. Furthermore, for example, when aluminum plating 20a and 30a are applied to the surface of the high-tensile steel plates constituting the inner panel 20 and outer panel 40, the molten aluminum plating 20a and 30a inside the molten pool flows and disperses, suppressing the reduction in strength due to localized concentration of the aluminum plating 20a and 30a.

[0021] <Clamp release process> After the laser welding process is completed, a clamp release process is performed. As shown in Figure 7, in the clamp release process, the clamp member C that clamped the inner panel 20 and the stiffener 30 is removed, and the clamp is released. In Figure 7, the location where the clamp member C was provided is drawn with a dashed line. The area where the clamp member C was provided does not have a laser welded section L.

[0022] <Spot welding process> After the clamp release process, a spot welding process is performed. First, as shown in Figures 8 and 10, the outer panel 40 is superimposed on the outside of the inner panel 20 and stiffener 30, which have been joined together by laser welding. At this time, the inner panel 20, stiffener 30 and outer panel 40 are fixed to each other by an appropriate method.

[0023] Next, as shown in Figures 9, 10, and 11, spot welding is performed between adjacent laser-welded sections L, connecting the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o of the inner panel 20, stiffener 30, and outer panel 40. This creates multiple spot-welded sections S on the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o. As shown in Figure 11, the spot-welded section S has a nugget N that spans the inner flange portions 20i, 30i, 40i (and outer flange portions 20o, 30o, 40o) of the inner panel 20, stiffener 30, and outer panel 40, respectively. The nugget N is spaced apart from the laser-welded sections L on both sides. Note that the symbol E in Figure 11 represents the electrode of the spot welding device. By following these steps, the vehicle body frame structure 10 according to this embodiment is completed.

[0024] Next, the details of the laser welding process will be explained with reference to Figures 12 and 13. Figure 12 is a magnified view of the area near the lower end of the center pillar during the laser welding process. For example, near the lower end of the center pillar 14, it is desirable to form a longer laser-welded section L to improve collision resistance. However, if the distance between the clamp members C is increased, the gap between the inner panel 20 and the stiffener 30 will increase, and it is anticipated that the required welding strength cannot be obtained.

[0025] Therefore, in this embodiment, as shown in Figure 12, three clamp members C (hereinafter referred to as "movable clamps C2") that are released during laser welding are installed between two clamp members C (hereinafter referred to as "fixed clamps C1") that are spaced apart from each other. These clamp members C clamp the inner flange portion 20i of the inner panel 20 and the inner flange portion 30i of the stiffener 30.

[0026] The two fixed clamps C1 are maintained during the laser welding process and released during the subsequent spot welding process. A laser-welded area L is formed in the region LA between the two fixed clamps C1. Meanwhile, the three movable clamps C2 are sequentially released during the laser welding process. For example, the laser beam LL is scanned from the upper fixed clamp C11 towards the lower fixed clamp C12, and the laser welded area L begins to form from the fixed clamp C11 side. Then, as the laser beam LL approaches the movable clamp C21, which is closest to the upper fixed clamp C11, the clamp of the movable clamp C21 is released.

[0027] As shown in Figure 12, after the movable clamp 21 is released, the laser beam LL passes through the position where the movable clamp 21 was clamping, continuously forming the laser welded area L. Then, as the laser beam LL continues to advance and approaches the movable clamp C22, the clamp of the movable clamp C22 is released, and the laser welded area L is continuously formed at the position where the movable clamp 22 was clamping. As the laser beam LL continues to advance and approaches the movable clamp C23, the clamp of the movable clamp C23 is released, and the laser welded area L is continuously formed at the position where the movable clamp 23 was clamping. As a result, even when the area LA between the two fixed clamps C1 is large, the laser welded area L can be continuously formed without causing a decrease in strength due to the gap.

[0028] Figure 13 is a schematic side view of the movable clamp. As shown in Figure 13, the movable clamp C2 comprises a main body C2b positioned below the inner panel 20 and a movable part C2a positioned above the stiffener 30. The movable part C2a has an arm C2a1 that extends toward the center of the door opening 16. The main body C2b has a bracket C2b1 that supports the base end of the arm C2a1 so that it can rotate around a horizontal axis. When the movable part C2a of the movable clamp C2 is rotated upward, the clamp of the movable clamp C2 is released. At this time, the tip of the movable part C2a moves to a position where it is not hit by the laser beam LL. In Figure 13, the movable part C2a before rotation is shown as a dashed line (two-dot dashed line). The movable part C2a can be rotated, for example, by an actuator of a robot arm (not shown). The timing for releasing the clamp of the movable clamp C2 is set based on the scanning speed of the laser beam LL and the distance between the laser beam LL and the movable clamp C2. For example, the robot arm may be controlled to release the clamp on the movable clamp C2 when the laser beam LL approaches a distance of 1 cm to 1.5 cm from the movable clamp C2.

[0029] Next, the effects and advantages of the manufacturing method for the vehicle body frame structure according to this embodiment will be described.

[0030] The manufacturing method for the vehicle body frame structure 10 according to this embodiment is a method for manufacturing the vehicle body frame structure 10 which is obtained by overlapping an inner panel 20, a stiffener 30, and an outer panel 40 made of galvanized steel sheet in this order from the inside of the vehicle, and joining the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o provided on the inner panel 20, stiffener 30, and outer panel 40 to each other, and a clamping step in which the inner flange portions 20i, 30i and outer flange portions 20o, 30o of the inner panel 20 and stiffener 30 overlap to each other and clamp the inner flange portions 20i, 30i and outer flange portions 20o, 30o of the inner panel 20 and stiffener 30 to each other with a plurality of clamp members C arranged at intervals from each other, The method comprises: a laser welding step of forming a plurality of laser-welded sections L of a predetermined length by performing continuous laser welding between adjacent clamp members C to join the inner flange sections 20i, 30i and outer flange sections 20o, 30o of the inner panel 20 and stiffener 30 together; a clamp release step of removing the clamp members C; and a spot welding step of overlapping the outer panel 40 on the outside of the vehicle of the inner panel 20 and stiffener 30 which have been laser-welded together, and spot welding the inner flange sections 20i, 30i, 40i and outer flange sections 20o, 30o, 40o of the inner panel 20, stiffener 30 and outer panel 40 together between adjacent laser-welded sections L to form a plurality of spot-welded sections S. With this configuration, the inner panel 20 and the stiffener 30 are continuously welded together by laser welding, thus forming a highly rigid vehicle frame. Since a gap between the inner panel 20 and the stiffener 30 can cause laser welding defects, the quality of the laser welding can be ensured by clamping the inner panel 20 and the stiffener 30 together to eliminate any gaps, and then laser welding between the clamps. Furthermore, since only the inner panel 20 and the stiffener 30, which contribute significantly to rigidity, are laser welded, manufacturing energy can be reduced compared to laser welding three panels, including the outer panel 40. Furthermore, the outer panel 40, which forms the outer surface, is made of galvanized material for rust prevention. When galvanized material is laser-welded, the area behind the laser irradiation point expands and explodes due to gas from the evaporation of the galvanized material, and then solidifies, causing blowholes, making it difficult to ensure welding quality. Therefore, the inner panel 20 and stiffener 30 are joined by laser welding to ensure rigidity as a vehicle frame, and then the outer panel 40 is overlapped and spot-welded, thereby achieving both rigidity and weldability. In addition, since the three plates are spot-welded at the position where the inner panel 20 and stiffener 30 were clamped, the joint between the inner panel 20 and stiffener 30 becomes even stronger, further improving rigidity.

[0031] Furthermore, the manufacturing method for the vehicle body frame structure 10 may be configured such that the plurality of clamp members C have a movable clamp C2 whose clamp is released during the laser welding process and a fixed clamp C1 whose clamp is maintained during the laser welding process, with the movable clamp C2 positioned between two fixed clamps C1, and the laser welding process includes a step of releasing the movable clamp C2 when the laser beam LL scanning between the two fixed clamps C1 approaches the movable clamp C2 and continuously laser welding the area that the movable clamp C2 was clamping. With this configuration, by positioning a movable clamp between two fixed clamps C1 that are spaced apart, the gap between the inner panel 20 and the stiffener 30 is kept small, and the clamp of the movable clamp C2 is released when the scanning laser beam LL approaches, allowing for seamless laser welding between the two fixed clamps C1 while maintaining welding quality.

[0032] Furthermore, the inner panel 20 and stiffener 30 are made of high-tensile steel, and the laser welding process may be configured to scan the laser beam LL along the welding line while wobbling. With such a configuration, high-strength high-tensile steel is continuously joined by laser welding, so a highly rigid vehicle body frame can be formed. In addition, by welding while correcting and stirring the molten pool with wobbling welding, the occurrence of blowholes can be suppressed and welding quality can be ensured. Furthermore, when hot-pressed material is used as a type of high-tensile steel, laser welding of hot-pressed material can cause the aluminum component to separate and solidify, resulting in defective areas with a high aluminum concentration. To address this problem, when laser welding hot-pressed material, the molten pool can be forcibly stirred by wobbling welding to disperse the aluminum plating component in the molten pool, thereby suppressing the formation of defective areas.

[0033] Furthermore, the vehicle body frame structure 10 according to this embodiment is formed by stacking the inner panel 20, stiffener 30, and outer panel 40 in this order from the inside of the vehicle, and joining the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o provided on the inner panel 20, stiffener 30, and outer panel 40 to each other. The inner flange portions 20i, 30i and outer flange portions 20o, 30o of the inner panel 20 and stiffener 30 to each other are joined by a plurality of laser-welded sections L formed to a predetermined length by continuous laser welding. In addition, the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o of the inner panel 20, stiffener 30, and outer panel 40 to each other are joined by spot-welded sections S formed by spot welding between adjacent laser-welded sections L. With this configuration, the inner panel 20, which is the first metal plate, and the stiffener 30, which is the second metal plate, are continuously welded together at the laser welding section L, thereby forming a highly rigid vehicle body frame. Furthermore, since only the inner panel 20 and the stiffener 30 are laser welded together, manufacturing energy can be reduced compared to laser welding all three plates, including the outer panel 40. In addition, the outer panel 40 is spot-welded between the laser welding section L to the inner panel 20 and the stiffener 30, which are joined together by laser welding, further strengthening the joint between the inner panel 20 and the stiffener 30 and improving rigidity performance.

[0034] Furthermore, the outer panel 40 does not have laser-welded sections L. In other words, the outer panel 40 is joined to the inner panel 20 and stiffener 30 only by spot welds S. With this configuration, even if the outer panel 40 is made of galvanized steel sheet, the outer panel 40 will not form blowholes that do not have laser-welded sections L. Therefore, by joining the inner panel 20 and stiffener 30 by laser welding to ensure rigidity as a vehicle body frame, and then overlapping and spot-welding the outer panel 40 made of galvanized steel sheet, both rigidity and weldability can be achieved.

[0035] Furthermore, the spot weld section S has a nugget N that spans the inner flange portions 20i, 30i, 40i and outer flange portions 20o, 30o, 40o of the inner panel 20, stiffener 30, and outer panel 40, respectively. With this configuration, since the nugget spans the inner panel 20, stiffener 30, and outer panel 40, the outer panel 40 can be reliably joined to the inner panel 20 and stiffener 30. In addition, since the inner panel 20 and stiffener 30 are joined not only by the laser weld section L but also by the spot weld section S, the joint becomes even stronger, improving rigidity performance.

[0036] Furthermore, the inner flange portions 20i, 30i, and 40i are formed along the periphery of the front door opening 16F and the rear door opening 16R, respectively. With this configuration, the vehicle body frame structure 10 according to this embodiment is used in the door opening 16, which has a high contribution to rigidity, thereby effectively improving rigidity and leading to weight reduction.

[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, in this embodiment, three movable clamps C2 are arranged between two fixed clamps C1, but the present invention is not limited thereto. The number of movable clamps C2 arranged between the two fixed clamps C1 may be one or four or more.

[0038] Furthermore, in this embodiment, the outer panel 40 is integrally constructed from a single galvanized steel sheet, but the present invention is not limited thereto. For example, the outer panel 40 may be constructed by dividing it from multiple galvanized steel sheets.

[0039] Furthermore, in this embodiment, the laser-welded portions L of the inner flange portions 20i and 30i around the rear door opening 16R are provided along the side sill portions 21 and 31, the roof rail portions 22 and 32, the center pillar portions 24 and 34, and the lower half of the rear pillar portions 25 and 35 (no laser-welded portions L are provided on the upper half of the rear pillar portions 25 and 35; see Figure 2). However, multiple laser-welded portions L may be provided around the entire circumference of the rear door opening 16R.

[0040] Furthermore, in this embodiment, the present invention was applied to the skeletal structure around the door on the side of the vehicle body, but the present invention may also be applied to other parts that constitute the skeletal structure of the vehicle body. [Explanation of Symbols]

[0041] 10. Vehicle frame structure 16 Door opening 16F Front door opening 16R Rear door opening 20 Inner Panel 30 Stifle 40 Outer Panels 21, 31, 41 Side sill section 22, 32, 42 Roof rail section 23, 33, 43 Front pillar section 24, 34, 44 Center pillar section 25, 35, 45 Rear pillar section 20i, 30i, 40i Inner flange section 20°, 30°, 40° outer flange section L Laser Welded Section Lw wobbling marks S spot weld C-clamp member C1 Fixing Clamp C2 Movable Clamp

Claims

1. A method for manufacturing a vehicle body frame structure, comprising stacking an inner panel, a stiffener, and an outer panel made of galvanized steel sheet in this order from the inside of the vehicle, and joining the flange portions provided on each of the inner panel, the stiffener, and the outer panel, A clamping step in which the flange portions of the inner panel and the stiffener are overlapped and the flange portions of the inner panel and the stiffener are clamped together with a plurality of clamping members that are spaced apart from each other, A laser welding process in which a plurality of laser-welded sections of a predetermined length are formed by performing continuous laser welding between adjacent clamp members to join the flange sections of the inner panel and the stiffener together, A clamp release step of removing the clamp member, A spot welding process is performed by overlapping the outer panel onto the outer side of the inner panel and stiffener, which have been laser-welded together, and spot welding the flange portions of the inner panel, stiffener, and outer panel together between adjacent laser-welded portions to form a plurality of spot welds. A method for manufacturing a vehicle body frame structure equipped with the above.

2. The plurality of clamping members include a movable clamp whose clamp is released during the laser welding process and a fixed clamp whose clamp is maintained during the laser welding process. The movable clamp is positioned between the two fixed clamps. The laser welding process includes a step of releasing the movable clamp and continuously laser welding the area that the movable clamp was clamping when the laser beam scanning between the two fixed clamps approaches the movable clamp. A method for manufacturing a vehicle body frame structure according to claim 1.

3. At least one of the inner panel and the stiffener is made of high-tensile steel. The aforementioned laser welding process involves scanning the welding line while wobbling the laser beam. The vehicle body frame structure according to claim 1.

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