Vehicle roof frame components and integrated blanks for vehicle roof frame components

Abstract

The present invention aims to shorten the manufacturing process of increasingly complex roof frame components and to obtain roof frame components by integral molding (integral press molding). A vehicle roof frame component can be obtained by press-molding an integrated blank having two roof rail inners extending in the direction of vehicle travel, one or more roof crosses connected to the two roof rail inners, and a joint where the blanks corresponding to the roof rail inners and the blanks corresponding to the roof crosses are joined at overlapping portions.

Description

[Technical Field]

[0001] The present invention relates to a vehicle roof frame component and an integrated blank for a vehicle roof frame component. [Background Art]

[0002] Reduction of life-cycle GHG (total greenhouse gas emissions over the entire life cycle) is demanded, mainly in automobiles and the like, and there is an increasing demand for integration of components and modules aimed at improving the efficiency of production lines by reducing the number of components and omitting processes. In particular, if large-sized components formed by combining a large number of members and parts, such as vehicle frame components, for example, automobile door rings and roofs, can be integrally molded (integrally press-formed), the effect will be extremely significant. For this reason, there is an increasing demand for integral press molding of frame components using blanks integrated by combining steel plates of different grades, so-called tailored blanks (TWB: Tailor Welded Blanks).

[0003] As an example of integral molding of vehicle frame members, integral molding of automobile side frame components (door rings) using TWB has been proposed (for example, Patent Document 1). Since different parts of an automobile door ring have different requirements for strength and plate thickness, it is manufactured by combining different types of steel plates (blanks), so the effect of omitting processes by integral molding using TWB is significant.

[0004] On the other hand, a frame component around the roof of a vehicle (roof frame component) is configured by arranging a plurality of roof cross members that connect the side frame components on both sides. Roof frame components also have different requirements for strength and plate thickness for each roof cross member, and are manufactured by combining different types of steel plates (blanks) in the same manner as side frame components. However, when actually assembling an automobile, the side frame components (door rings) on both sides are assembled first, and the roof cross members are attached one by one to connect them. Therefore, it takes time to manufacture and attach the roof cross members, and there is a demand for reducing the attachment time of roof frame components. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2020 / 002335 [Overview of the project] [Problems that the invention aims to solve]

[0006] As vehicle safety becomes an increasingly important factor, there is a demand for improved impact resistance of roof frames to ensure sufficient interior space during side collisions and rollovers. Furthermore, the increasing diversity of vehicle designs, such as sunroofs, and the demand for lighter vehicle weights are complicating the construction of roof frames. Consequently, the manufacturing process for roof frames is also becoming more complex, leading to increased manufacturing costs, and there is a growing need for simplification of the manufacturing process and cost reduction.

[0007] The present invention aims to shorten the manufacturing process of increasingly complex roof frame components and to obtain roof frame components by integral molding (integral press molding). [Means for solving the problem]

[0008] To achieve the above objectives, the inventors diligently developed a vehicle roof frame component based on an automobile roof frame, incorporating the perspective of shortening the manufacturing process through integral molding. Specifically, instead of joining each roof cloth to the door ring one by one, they focused on integrally molding a roof frame component with the roof cloth already arranged. As a result, they obtained the following findings.

[0009] (a) We noticed that in automobile assembly, the roof cloth is joined to the roof rail inner (a part of the roof rail that is located on the inside of the vehicle). Therefore, we conceived of positioning the roof rail inner as a part of the roof frame component and proceeded with development by integrally molding the roof rail inner on both sides with the roof cloth.

[0010] (stomach) The roof rail inners and roof cross on both sides are not formed from a single type of blank (steel material), but are often composed of multiple blanks. Therefore, we discovered that it is possible to manufacture an integrated blank by joining the blanks corresponding to the roof rail inners and roof cross in advance and then forming a TWB (Two-Way Joint).

[0011] (cormorant) The resulting integrated blank can be press-formed to obtain the desired roof frame component in a single press-forming process. Since high-tensile steel (Hi-Ten) is often used as the blank, hot stamping is preferable for the press-forming method, and it has been found that conventional hot stamping methods can also be applied.

[0012] (workman) We discovered that by using an overlapping joint between the roof rail inner and the roof cloth, the thickness of the plate at the joint increases, thus maintaining the rigidity of the conventional roof rail inner. This allows for the creation of an integrally molded roof frame component without reducing the strength of the door ring (side frame).

[0013] (O) Furthermore, we discovered that the rigidity of the joint can be increased by press-forming a bead at the joint between the roof rail inner and the roof cloth.

[0014] This invention is based on the above findings, and its purpose is as follows.

[0015] [1] A vehicle roof frame component that forms the roof portion of a vehicle and is made up of multiple steel plates joined together, The aforementioned roof frame component is It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, The blank corresponding to the roof rail inner and the blank corresponding to the roof cloth have a joint where they are joined at the overlapping portion where they are superimposed on each other. A vehicle roof frame component characterized by the following features. [2] The joint is a vehicle roof frame component according to [1] that is located in the overlapping portion of the joint where at least one roof rail inner and at least one roof cross are connected. In other words, A vehicle roof frame component that forms the roof portion of a vehicle and is made up of multiple steel plates joined together, The aforementioned roof frame component is It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, In the connection portion where at least one of the roof rail inners and at least one of the roof crosses are connected, The blank corresponding to the roof rail inner and the blank corresponding to the roof cloth have a joint where they are joined at the overlapping portion where they are superimposed on each other. A vehicle roof frame component characterized by the following features. Typically, the connection is an area enclosed by a virtual line indicating the width of the roof rail inner and a virtual line indicating the width of the roof cloth, and at least a portion of the overlap is the vehicle roof frame component described in [2] which is located inside the connection. [3] The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner includes at least a top plate portion extending in a longitudinal direction of the roof rail inner and at least one standing wall portion adjacent to the top plate portion, The vehicle roof frame component according to [1] or [2], wherein the connecting portion is connected such that the roof cross abuts against the standing wall portion of the roof rail inner. [4] The vehicle roof frame component according to [3], wherein the overlapping portion is disposed at least on the top plate portion of the roof rail inner. [5] The vehicle roof frame component according to any one of [1] to [4], wherein the roof cross has a bead that passes through the overlapping portion and extends in a longitudinal direction of the roof cross. [6] The vehicle roof frame component according to any one of [1] to [5], wherein the roof rail inner has a bead that passes through the overlapping portion and extends in a longitudinal direction of the roof rail inner. [7] The vehicle roof frame component according to any one of [1] to [6], wherein the roof frame component is a hot-stamped component. [8] The vehicle roof frame component according to any one of [1] to [7], wherein at least one of the joint portions is a joint portion free of a HAZ softened portion. [9] For the joint portion free of a HAZ softened portion, in a cross section perpendicular to a surface of an outermost blank including a center of the joint portion, at a position 3 / 4 of a plate thickness from the surface of the outermost blank, where letting Hvm be the Vickers hardness at a position 15 mm or more away from the center of the joint portion and not joined, ΔHv, which is the difference between the maximum Vickers hardness and the minimum Vickers hardness in a range within 5 mm toward the base material side from an end of a weld metal of the joint portion, is 0.2 Hvm or less (preferably ΔHv is 0.1 Hvm or less) (that is, there is no HAZ softened portion). The vehicle roof frame component according to [8].[ That is, the joint portion free of a HAZ softened portion is a joint portion in which ΔHv is 0.2 Hvm or less (preferably, ΔHv is 0.1 Hvm or less).

[10] The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The joint portion without the HAZ softening portion is the vehicle roof frame component described in [8] or [9] that is present in either or both the top plate portion of the roof rail inner and the top plate portion of the roof cloth.

[11] A press-formed integrated blank configured as a joint structure for multiple steel plates for a vehicle roof frame component that constitutes the roof of a vehicle, The aforementioned roof frame component is It has two roof rail inners extending in the direction of vehicle travel, and one or more roof crosses connected to the two roof rail inners, The aforementioned integrated blank is It has two blanks corresponding to the roof rail inner that extend in the direction of vehicle travel, It has one or more blanks corresponding to a roof cross that are connected to the two blanks corresponding to roof rail inners, An integrated blank for a vehicle roof frame component, characterized in that at least one blank corresponding to the roof rail inner and at least one blank corresponding to the roof cloth have a joint portion joined at an overlapping portion where they are superimposed on each other. Typically, at least a portion of the overlapping portion is an integrated blank for a vehicle roof frame component as described in

[11] , which is located within a region enclosed by a virtual line indicating the width of the blank corresponding to the roof rail inner and a virtual line indicating the width of the blank corresponding to the roof cloth.

[12] The blank corresponding to the roof cloth comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The blank corresponding to the roof rail inner comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The overlapping portion is an integrated blank for a vehicle roof frame component according to

[11] , which is arranged in a portion corresponding to the top plate portion of the blank corresponding to the roof rail inner.

[13] The integrated blank for a vehicle roof frame component according to

[11] or

[12] , wherein the joint is a joint formed by resistance spot welding, laser spot welding, or overlap welding.

[14] The joint portion is an integrated blank for a vehicle roof frame component according to any one of the items

[11] to

[13] , which is located in at least one of the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner and the portion corresponding to the top plate portion of the blank corresponding to the roof cloth. [Effects of the Invention]

[0016] According to the present invention, a vehicle roof frame component can be obtained by integrally molding an integrated blank (TWB) formed by joining multiple partial blanks, thereby drastically shortening the manufacturing process for the roof frame component. [Brief explanation of the drawing]

[0017] Figure 2 is divided into Figure 2-1 and Figure 2-2, but these are combined to form Figure 2. [Figure 1] This is a schematic diagram illustrating an embodiment of the present invention concerning a roof frame for an automobile. Figure 1(a) is a schematic diagram showing an example of an automobile frame. Figure 1(b) is a schematic diagram of a roof frame component according to an embodiment of the present invention. [Figure 2]Figure 1(b) is a schematic diagram illustrating an example of the roof frame component and its integrated blank according to the present invention. Figure 2(a) is a schematic diagram showing an example of the roof frame component and the integrated blank constituting the roof frame component superimposed on Figure 1(b). Figure 2(b) is a schematic diagram showing the integrated blank of Figure 2(a). It is a schematic diagram for illustrating the form of the overlapping portion of the roof rail inner equivalent blank and the roof cloth equivalent blank. Figure 2(c) is a schematic diagram showing the roof frame component of Figure 2(a). It is a schematic diagram for illustrating the connection portion and overlapping portion of the roof rail inner and the roof cloth. [Figure 3] This is a schematic diagram illustrating the connection between the roof rail inner and the roof cloth. Figure 3(a) is a schematic diagram of the connection when integrally molded, which is an embodiment of the present invention. Figure 3(b) is a schematic diagram of the connection between a conventional roof rail inner and roof cloth. [Figure 4] Figure 4 is a schematic diagram illustrating an example of the joining state at the connection point between the roof rail inner and the roof cloth. Figure 4(a) shows an example of the connection point as a roof frame component after press forming, and Figure 4(b) is a schematic diagram showing an example of the integrated blank of that connection point. Note that Figure 4(a) is a view from the inside of the vehicle. [Figure 5] This is a schematic diagram illustrating beads provided on the roof cloth. Figure 5(a) is a schematic diagram illustrating two rows of beads formed on the top surface of the roof cloth. Figure 5(b) is a schematic diagram illustrating a cross-section of the bead-formed section of the roof cloth in the longitudinal direction. Note that Figure 5(a) is a view from the inside of the vehicle, and in Figure 5(b), the bottom of the drawing is in the direction of the outside of the vehicle. [Figure 6] This is a schematic diagram illustrating beads provided on the roof cloth that pass through the roof rail inner. Figure 6(a) is a schematic diagram illustrating two rows of beads formed on the top plate portion of the roof cloth. Figure 6(b) is a schematic diagram illustrating a cross-section of the bead-forming portion in the longitudinal direction of the roof cloth. Note that Figure 6(a) is a view from the inside of the vehicle, and in Figure 6(b), the bottom of the drawing is in the direction of the outside of the vehicle. [Figure 7]This is a schematic diagram illustrating a case where beads are formed using both the roof cloth and the roof rail inner. Figure 7(a) is a schematic diagram illustrating a case where two rows of beads are formed on the top surface of the roof cloth and one row of beads is formed on the top surface of the roof rail inner. Figure 7(b) is a schematic diagram illustrating a cross-section of the bead-formed area in the longitudinal direction of the roof cloth. Note that Figure 7(a) is a view from the inside of the vehicle, and in Figure 7(b), the bottom of the drawing is in the direction of the outside of the vehicle. [Figure 8] This is a diagram illustrating the manufacturing process of a part by press forming of a TWB (integrated blank) according to an embodiment of the present invention. [Figure 9] This is a diagram illustrating the softened area of ​​the heat-affected zone (HAZ) caused by spot welding. [Modes for carrying out the invention]

[0018] This embodiment will be described using an example of an automobile roof frame, which is one embodiment (hereinafter simply referred to as "this embodiment") of a vehicle roof frame component that constitutes the roof portion of a vehicle according to the present invention. Figure 1 shows an overview of an automobile frame 100. Figure 1(a) shows an overview of a general automobile frame 100, and Figure 1(b) shows an overview of a roof frame component 101 that imitates it as an embodiment. In Figure 1, the direction of the white arrow in the drawing is the direction of vehicle travel.

[0019] The roof frame component 101 according to this embodiment is a component that constitutes the roof portion (upper surface (top plate portion)) of an automobile vehicle, and is composed of two roof rail inners 11 extending in the direction of vehicle travel and one or more (three in Figure 1(b)) roof crosses 12 connected to these two roof rail inners 11. The number of roof crosses 12 is not particularly limited, and one or more are sufficient, but it is preferable to have two or more for the structure of the automobile.

[0020] The roof rail inners 11 extend in the direction of vehicle travel and are arranged in parallel, spaced apart in the vehicle width direction (perpendicular to the direction of vehicle travel), defining the width of the vehicle. The roof cross 12 is connected to these two roof rail inners 11 and abuts against them. The part where the roof cross 12 connects to the roof rail inners 11 is called the connection part.

[0021] The shape of the roof rail inner 11 is not particularly limited. Typically, the roof rail inner 11 has a top plate portion extending in the longitudinal direction and at least one vertical wall portion adjacent to the top plate portion. That is, the cross-sectional shape of the roof rail inner 11 in a cross section perpendicular to the longitudinal direction (hereinafter, the cross-sectional shape in a cross section perpendicular to the longitudinal direction is simply referred to as the cross-sectional shape) is often a hat shape, C shape, L shape, etc. The cross-sectional shape of the roof rail inner in this embodiment is based on an L shape with one vertical wall portion adjacent to the top plate portion, and flange portions are arranged on the top plate portion and the vertical wall portion. Therefore, it is composed of a flange portion, a top plate portion, a vertical wall portion, and a flange portion in that order.

[0022] The shape of the roof cloth 12 is not particularly limited. Typically, the roof cloth 12 has a top plate portion extending in the longitudinal direction and at least one vertical wall portion adjacent to the top plate portion. That is, the cross-sectional shape of the roof cloth 12 is often a hat shape, C shape, L shape, etc. The cross-sectional shape of the roof cloth 12 in this embodiment has two vertical wall portions adjacent to the top plate portion, and flange portions are arranged on both vertical wall portions, resulting in a so-called hat-shaped structure. Therefore, it is composed of a flange portion, a vertical wall portion, a top plate portion, a vertical wall portion, and a flange portion in that order.

[0023] The roof cross 12 is connected so as to connect the two roof rail inners 11 and abut against the roof rail inners 11, but typically the roof cross 12 is connected so as to abut against the vertical wall of the roof rail inners 11.

[0024] In this embodiment, a roof rail inner 11 is used, but it does not have to be the roof rail inner 11 itself; for example, a roof rail inner-like component may be used. This is because when assembling the automobile, the roof rail inner-like component can be attached to the roof rail inner of the door ring, allowing the automobile to be assembled. This embodiment is an example in which a roof rail inner is used, and this embodiment will be explained using this example.

[0025] In conventional automobile frame structures, the roof rail inner is included in the side frame component (door ring), and during automobile assembly, after assembling the door rings on both sides in the width direction of the automobile, the roof cloth is joined one by one to the roof rail inner, which is a part of the door ring (for example, by spot welding). In the roof frame component according to this embodiment, the roof rail inner is positioned as a part (a single component) of the roof frame component, making it possible to integrally mold the roof rail inner on both sides and the roof cloth.

[0026] Figure 2(b) shows a schematic diagram of the integrated blank 201 for a vehicle roof frame component according to this embodiment. The roof rail inner 11 and roof cross 12 on both sides are not formed from a single type of steel plate (blank), but are often constructed as a joined structure of multiple steel plates (blanks). Therefore, the integrated blank 201 can be manufactured by joining blanks corresponding to the roof rail inner 11 and roof cross 12 in advance to form a TWB.

[0027] The integrated blank according to this embodiment corresponds to the roof frame component according to this embodiment. That is, the integrated blank according to this embodiment has two blanks corresponding to roof rail inners extending in the direction of vehicle travel, and one or more blanks corresponding to roof crosses connected to the two blanks corresponding to roof rail inners, and at least one of the blanks corresponding to roof rail inners and at least one of the blanks corresponding to roof crosses have a joint where they are joined by overlapping portions that are superimposed on each other, making it an integrated blank for a vehicle roof frame component.

[0028] Figure 2(a) shows a schematic diagram overlaying an example of an integrated blank and a molded roof frame component, separated by the blanks that make up the roof frame component in Figure 1(b). In the example in Figure 2(a), the integrated blank 201 for the vehicle roof frame component is composed of two blanks corresponding to roof rail inners 11 (roof rail inner equivalent blanks 21) and three blanks corresponding to roof crosses 12 (roof cross equivalent blanks 22). Even within a single roof rail inner equivalent blank 21, multiple different steel plates (blanks) can be joined to form the roof rail inner equivalent blank 21. The strength and thickness of the steel plates to be used can be determined as needed based on the structural design of the automobile.

[0029] Similarly, within a single roof cross equivalent blank 22, multiple different steel plates (blanks) can be joined together to form the roof cross equivalent blank 22, and the strength and thickness of the steel plates to be used can be determined by the structural design. Also, although three roof cross equivalent blanks 22 can be seen in Figure 2(a), the type of steel plate may differ in each roof cross equivalent blank 22, and this can also be determined as needed in the structural design.

[0030] In manufacturing the integrated blank 201, the usual TWB manufacturing method can be applied. However, from the viewpoint of ensuring the strength and rigidity of the part where the roof rail inner 11 and the roof cloth 12 connect, it is preferable to overlap and join the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the connection part 31 between the roof rail inner 11 and the roof cloth 12. Here, the part where these two blanks overlap is called the overlapping part 41, and the joined part (for example, the welded part) is called the joint part 51.

[0031] The connection portion 31 between the roof cloth 12 and the roof rail inner 11 is the area enclosed by the imaginary line 311, which represents the width of the roof rail inner 11, and the imaginary line 312, which represents the width of the roof cloth 12, in the roof frame component 101, as shown in Figure 2(c).

[0032] Figure 2(c) shows the roof frame component 101 shown in Figure 2(a). In Figure 2(c), the area enclosed by the imaginary line 311 indicating the width of the roof rail inner 11 and the imaginary line 312 indicating the width of the roof cross 12 is the connection portion 31. For the sake of explanation, only the connection portion 31 relating to the lower roof rail inner 11 of the roof frame component 101 in Figure 2(c) is shown. The upper roof rail inner 11 also has a similar connection portion, but to avoid overlapping with the display of the overlapping portion, only the connection portion of the lower roof rail inner 11 is shown.

[0033] As can be seen from Figure 2(c), the imaginary line 311 indicating the width of the roof rail inner 11 is a line that indicates the outer edge (end face) of the roof rail inner 11 in the direction perpendicular to the longitudinal direction (width direction). If the line indicating the end face is interrupted, the lines indicating the end face before and after the interruption are extended or supplemented to draw a smoothly continuous imaginary line. For example, when the roof rail inner 11 is viewed in a cross section perpendicular to the longitudinal direction, if it has a hat-shaped cross section (a shape with a top plate in the center, vertical walls on both sides of it, and flanges on both sides of the vertical walls), the lines corresponding to the outer edges of both flanges become the imaginary line 311 indicating the width of the roof rail inner 11. For example, if the roof rail inner 11 has a U-shaped cross section (a shape with a top plate in the center, and vertical walls on both sides of it), the lines corresponding to the outer edges of both vertical walls become the imaginary line 311 indicating the width. In parts where the flange or vertical wall is interrupted, the outer edges of the flange or vertical wall before and after the interruption are smoothly extended or supplemented to draw the imaginary line.

[0034] As can also be seen from Figure 2(c), the imaginary line 312 indicating the width of the roof cloth 12 is defined as a line drawn perpendicular to the longitudinal direction of the roof rail inner 11 from the intersection of the outer edge (end face) of the roof cloth 12 in the direction perpendicular to the longitudinal direction (width direction) and the imaginary line 311 indicating the width of the roof rail inner 11 (i.e., the intersection of the width direction end face (outer edge) of the roof cloth 12 after pressing and the width direction end face (outer edge) of the roof rail inner 11). In the example in Figure 2(c), at the point where the roof cloth 12 connects to the roof rail inner 11, the width of the roof cloth 12 gradually increases as it connects to the roof rail inner 11. Therefore, the outer edge of the roof cloth 12 in the width direction also spreads outward and intersects with the imaginary line 311 of the roof rail inner 11, so the spacing of the imaginary lines 312 of the roof cloth 12 is wider than the width of the middle part of the roof cloth 12.

[0035] The overlapping portion 41 is the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are superimposed. Since both blanks are press-formed while superimposed, the overlapping portion 41 of both blanks remains in the roof frame part after press-forming. Figure 2(c) shows the overlapping portion 41 of the roof frame part 101, which is the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are superimposed. As mentioned above, for the sake of explanation, the overlapping portion 41 relating to the upper roof rail inner 11 of the roof frame part 101 in Figure 2(c) is shown.

[0036] The overlapping portion 41 is positioned so that at least a part of it is inside the connecting portion 31. In the conceptual diagram of Figure 2(c), parts of the two overlapping portions 41 at the front of the vehicle (left side of the drawing) are positioned so as to overlap the entire connecting portion 31. It is desirable that the proportion of the connecting portion 31 over which the overlapping portion 41 overlaps is as large as possible. Preferably, the overlapping portion 41 overlaps 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the connecting portion 31. The overlapping portion 41 is often T-shaped, as in the left and center roof cross 12 and roof rail inner 11 in Figure 2(c), but it can also be L-shaped, as in the right roof cross 12 and roof rail inner 11 in Figure 2(c).

[0037] The method of overlapping the roof rail inner equivalent blank 21 and the roof cross equivalent blank 22 at the overlapping portion 41 of the two blanks is not particularly limited. Figure 2(b) shows an integrated blank of the roof frame component shown in Figure 2(a). Figure 2(b) is a schematic diagram showing an example of how the roof rail inner equivalent blank 21 and the roof cross equivalent blank 22 are overlapped in an example of an integrated blank 201. For example, in Figure 2(b), at the overlapping portion 41 of the upper roof rail inner equivalent blank and the leftmost of the three roof cross equivalent blanks 22, the roof cross equivalent blank 22 has a portion that protrudes on one side of its end toward the longitudinal direction of the roof rail inner equivalent blank 21, and the roof rail inner equivalent blank 21 has a portion that protrudes toward the roof cross equivalent blank 22, thus forming an L-shaped overlapping portion 41. Furthermore, the upper overlapping portion 41 of the middle roof cross equivalent blank 22 forms an overlapping portion 41 in which the roof cross equivalent blank 22 has portions that protrude on the longitudinal side of the roof rail inner equivalent blank 21 on both sides of its end. The upper overlapping portion 41 of the rightmost roof cross equivalent blank 22 forms an overlapping portion 41 in which only one side of the end of the roof cross equivalent blank 22 has a portion that protrudes onto the roof rail inner equivalent blank 21. These may be combined to form an overlapping portion 41. For example, as with the lower overlapping portion 41 of the middle roof cross equivalent blank 22, the roof rail inner equivalent blank 21 may have a portion that protrudes towards the roof cross equivalent blank 22, and the roof cross equivalent blank 22 may have portions that protrude on the longitudinal side of the roof rail inner equivalent blank 21 on both sides of its end, forming a T-shaped overlapping portion 41.

[0038] Furthermore, in the example shown in Figure 2(b), the overlapping portions 41 on both sides of the right and left roof cross equivalent blanks 22 (the overlapping portions with the two roof rail inner equivalent blanks 21) have almost the same shape, but the overlapping portions 41 at both ends may have different shapes, as in the middle roof cross.

[0039] In either case, it is preferable to join the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the overlapping portion 41. That is, the joint (the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are joined by welding or the like) will be located within the overlapping portion 41.

[0040] By joining the overlapping portion 41 of the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 and integrally molding (press molding) them, the shapes of both can be made to match during press molding. Figure 3(a) shows an overview of the connection portion 31 when the overlapping portion 41 is integrally molded. Figure 3(b) shows an overview of the connection portion 31 of the conventional roof rail inner 11 and roof cloth 12. Conventionally, the roof rail inner 11 and the roof cloth 12 were manufactured separately and joined together, so the top plate portion 111, vertical wall portion 112, and flange portion 113 of the roof rail inner were continuous, and thus had a certain rigidity against bending moments transmitted from the roof cloth 12. However, as shown in Figure 3(a), when integrally molded, the vertical wall portion 112 and flange portion 113 of the roof rail inner become discontinuous as if they were separated at the connection portion, and an opening is formed in the vertical wall portion of the roof rail inner 11. As a result, the bending rigidity of the roof rail inner 11 against bending received from the roof cloth 12 is weakened. Therefore, by overlapping and joining the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the connection point, the thickness of the connection point 31 can be increased, compensating for the discontinuity of the vertical wall portion 112 and flange portion 113 of the roof rail inner and ensuring rigidity.

[0041] Since the roof cross 12 is usually a hat-shaped cross section (a structure having a top plate portion 121 and vertical wall portions 122 on both sides, and flange portions 123 on both sides thereafter) or a C-shaped cross section (a structure having a top plate portion and vertical wall portions on both sides), it is preferable to place at least the overlapping portion 41 on the top plate portion 111 of the roof rail inner. In that case, it is preferable to place at least the joint portion 51 of the overlapping portion 41 on the top plate portion 111 of the roof rail inner. This is because the top plate portion does not undergo complex bending during press forming, and the material flow behavior is simple, so less load is placed on the joint portion (welded portion). The portion of the overlapping portion other than the top plate portion 111 of the roof rail inner may be joined after forming (press forming). By joining after forming, the joint portion is not affected by the stress and strain generated by the complex material flow behavior during press forming, so cracking can be suppressed.

[0042] Figure 4 shows an example of the joining state at the connection between the roof rail inner and the roof cloth. Figure 4(a) shows an example of the connection as a roof frame component after press forming, and Figure 4(b) shows an example of the integrated blank of the connection. Figure 4(a) is a view from the inside of the vehicle. The roof cloth 12 illustrated in Figure 4(a) has a hat-shaped cross section (a structure having a top plate portion 121 and vertical wall portions 122 on both sides of it, and flange portions 123 on both sides of those), and the roof rail inner 11 has a top plate portion 111 and a vertical wall portion 112 adjacent to one side, and flange portions 113 on the other side of the top plate portion 111 and on the vertical wall portion 112, resulting in a cross-sectional shape that resembles overlapping L-shaped cross sections.

[0043] When joining the roof rail inner and the roof cloth, it is preferable to join them at the overlapping portion of the top plate portion 111 of the roof rail inner and the top plate portion 121 of the roof cloth, as shown in Figure 4(a). In other words, the joint portion 51 will be located at the overlapping portion of the top plate portion 111 of the roof rail inner and the top plate portion 121 of the roof cloth.

[0044] Figure 4(b) shows an integrated blank for obtaining the connection part shown in Figure 4(a). In the example in Figure 4(b), the roof rail inner equivalent blank 21 is composed of a portion corresponding to the top plate portion of the roof rail inner (top plate equivalent portion) 211, a portion corresponding to the vertical wall portion (vertical wall equivalent portion) 212, and a portion corresponding to the flange portion (flange equivalent portion) 213. Similarly, the roof cloth equivalent blank 22 (the portion enclosed by the thick line in Figure 4(b)) is composed of a portion corresponding to the top plate portion of the roof cloth (top plate equivalent portion) 221, a portion corresponding to the vertical wall portion (vertical wall equivalent portion) 222, and a portion corresponding to the flange portion (flange equivalent portion) 223. In the integrated blank, as shown in Figure 4(b), it is preferable to place the joint portion 51 on at least one of the top plate equivalent portion 211 of the roof rail inner equivalent blank and the top plate equivalent portion 221 of the roof cloth equivalent blank within the overlapping portion 41 of the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 222. Preferably, a joint should be placed on at least one of the overlapping portion 41 of both blanks 21 and 22, specifically the portion corresponding to the top plate of the roof rail inner and the portion corresponding to the top plate of the roof cloth equivalent blank. More preferably, at least in the portion corresponding to the connection in the press-formed part, there should be a joint joined at the overlapping portion 41 of both blanks 21 and 22. In the example in Figure 4(b), a joint should be placed at least on the portion corresponding to the top plate of the roof rail inner among the overlapping portion 41 of both blanks 21 and 22. Figure 4(b) shows an example where three joints 51 (black dots) are placed on the portion corresponding to the top plate of the roof rail inner equivalent blank 211 and five joints 51 (black dots) are placed on the portion corresponding to the top plate of the roof cloth equivalent blank 221 (in Figure 4(b), a code line is drawn at only one location for clarity). The number and arrangement of the joints 51 are not particularly limited. They can be appropriately determined from the viewpoint of part strength design, weldability, workability, productivity, etc.

[0045] Regarding the overlapping portion 41 of the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22, when the roof cloth portion takes on a hat-shaped cross section, it is preferable to overlap them so that the roof cloth equivalent blank 22 is positioned above the roof rail inner equivalent blank 21 in the direction of the convexity of the hat shape. By arranging them in this way, cracking can be suppressed by allowing the blank material to flow smoothly during press forming without applying excessive stress to the blank material or welded parts.

[0046] The joining method is not particularly limited. For example, joining can be done by spot welding (resistance spot welding, laser spot welding, etc.), lap welding (arc welding, laser welding), lap fillet welding (arc welding, laser welding), brazing, friction stir welding (FSW), friction pressure welding, etc. Usually, from the standpoint of ease of welding and productivity, joining by spot welding is preferable. Figure 4 shows an example of a joint 51 in the case of spot welding.

[0047] In conventional methods of connecting the roof rail inner 11 and the roof cloth 12, the roof cloth 12 was welded to the vertical wall portion 112 of the roof rail inner so as to abut against it, resulting in a step at the joint. When the roof panel (automobile ceiling panel) was placed on the roof cloth 12, a gap inevitably formed at this joint, and when the automobile was electrodeposited, paint liquid accumulated in this gap, causing deterioration of the paint quality. In this embodiment, the connection part is integrally press-formed at the overlapping portion, allowing for a smooth connection from the roof cloth 12 to the roof rail inner 11. Since there is no step at the connection part between the roof cloth 12 and the roof rail inner 11, paint liquid does not accumulate. Therefore, according to this embodiment, an improvement in the electrodeposited paint quality of automobiles can also be expected.

[0048] [Bead] By forming a bead at the connection point between the roof rail inner and the roof cloth, the strength and rigidity of the connection point can be increased. Here, a bead refers to a convex projection (or concave groove) formed by press molding or the like. For example, it is preferable to form a bead that passes through the overlapping portion of the roof rail inner equivalent blank and the roof cloth equivalent blank and extends in the longitudinal direction of the roof cloth. If the roof cloth has a hat-shaped or C-shaped cross section, it is preferable to form the bead on the top surface. This bead provides high rigidity against bending moments transmitted from the roof cloth, improving the impact resistance of the vehicle when it rolls over. Furthermore, forming a bead can suppress springback after pressing. There is no particular limit to whether the bead is convex or concave, but from the viewpoint of securing internal space in the vehicle, it is preferable to make it convex on the outside of the vehicle. There is no particular limit to the number of beads. One or more will be effective. Figure 5 shows an example of a bead formed on the roof cloth. Figure 5(a) shows an overview of a roof cloth with two rows of beads 61 formed. Figure 5(b) shows a cross-sectional view. Figure 5(a) is a view from inside the vehicle, and Figure 5(b) shows a cross-section in the longitudinal direction of the roof cross, with the top of the drawing facing the inside of the vehicle and the bottom facing the outside of the vehicle. The length of the bead is not limited as long as it passes through the overlapping section. The required length can be determined by structural design, etc.

[0049] Figure 6 shows the case where the bead 61 formed on the roof cloth 12, as shown in Figure 5, passes through the roof rail inner 11. By having the bead 61 pass through the roof rail inner 11, the rigidity of the roof rail inner 11 can be further increased against bending moments from the roof cloth 12. Figure 6(a) shows an overview of the bead formation in this case, and Figure 6(b) shows a cross-sectional view in the longitudinal direction of the roof cloth. Figure 6(a) is a view from the inside of the vehicle, and Figure 6(b) shows a cross-section in the longitudinal direction of the roof cloth, with the top of the drawing being in the direction of the inside of the vehicle and the bottom being in the direction of the outside of the vehicle. However, when forming a bead that passes through the roof rail inner, depending on the shape of the roof rail inner and the roof cloth, the material flow during press forming becomes complicated, and cracks may occur when the bead is formed. For this reason, it is preferable to determine the bead shape by anticipating the material flow during press forming based on the shape of the roof rail inner and the roof cloth, as well as the shape of the connection part.

[0050] Additionally, beads may be formed on the roof rail inner, extending in the longitudinal direction of the roof rail inner. This compensates for the reduction in strength and rigidity caused by discontinuities (disconnections) in the vertical wall or flange portions of the roof rail inner. In this case, it is preferable to form the beads on the top plate or vertical wall portion of the roof rail inner. In this case as well, there is no particular limit to whether the beads are convex or concave, but from the viewpoint of securing internal space in the vehicle, it is preferable to make them convex toward the outside of the vehicle. There is also no particular limit to the number of beads. One or more beads will be sufficient to achieve the desired effect.

[0051] The roof cloth bead and the roof rail inner bead may be formed in combination. Figure 7 shows a conceptual diagram of this combined case. Figure 7(a) is an external view, and Figure 7(b) shows a longitudinal cross-section of the roof cloth 12. Figure 7(a) is a view from the inside of the vehicle, and Figure 7(b) shows a longitudinal cross-section of the roof cloth, with the top of the drawing being the direction towards the inside of the vehicle and the bottom being the direction towards the outside of the vehicle. The bead 61 of the roof cloth 12 and the bead 61 of the roof rail inner 11 may intersect. However, if the bead 61 of the roof cloth 12 and the bead 61 of the roof rail inner 11 intersect, the material flow behavior during press forming at the intersection becomes complex and may induce cracking of the blank, so it is preferable not to have the two beads intersect. Also, if the beads intersect, discontinuities occur in the walls that make up the bead groove at the intersection of the vertical wall beads, which reduces the effect of the beads in increasing rigidity, so it is undesirable.

[0052] <Manufacturing method for roof frame components> The method for manufacturing the roof frame components according to this embodiment is not particularly limited. They can be manufactured according to conventional methods. An overview of the manufacturing process in this embodiment is shown in Figure 8, which is the same as general integral press molding using a TWB.

[0053] Blanking process: This is the process of manufacturing blanks that will become the parts of an integrated blank. Blanks are cut from a specified steel plate (blanking), and then refined using laser trimming and other methods to produce blanks for each individual part.

[0054] Integrated blanking process for presses: This process involves joining multiple blanks to produce a TWB, which is a single, integrated blank for press forming. In this process, at least one roof cloth-equivalent blank and at least one roof rail inner-equivalent blank are joined at the overlapping portion where they are superimposed on each other. The method of joining the overlapping portion is not particularly limited, but joining by spot welding (resistance spot welding or laser spot welding) is an efficient method. The joining method for the other blanks is not particularly limited. When welding blanks together, laser welding or arc welding can be used. When blanks are superimposed, the joining of the overlapping portion can be done by spot welding (resistance spot welding, laser spot welding, etc.), overlap welding (arc welding, laser welding), overlap fillet welding (arc welding, laser welding), brazing, friction stir welding (FSW), friction pressure welding, etc. A TWB for press forming can be obtained by combining and joining predetermined blanks to form a single, integrated blank.

[0055] In manufacturing the integrated blank, as described above, at least one roof cloth equivalent blank and a roof rail inner equivalent blank are joined together at an overlapping portion where they are superimposed on each other. In the roof frame component after integral molding, at least a portion of the overlapping portion is located inside the connection portion. To achieve this, in manufacturing the integrated blank, at least a portion of the overlapping portion of the blank is located inside the area enclosed by a virtual line indicating the width of the roof rail inner equivalent blank and a virtual line indicating the width of the roof cloth equivalent blank. Preferably, the overlapping portion 41 of the blank is located so as to include an area of ​​50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the area enclosed by the virtual lines indicating the widths of both blanks.

[0056] The imaginary line 321 indicating the width of the roof rail inner equivalent blank 21 is, as shown in Figure 4(b), a line indicating the outer edge (end face) of the roof rail inner equivalent blank 21 in the direction perpendicular to the longitudinal direction (width direction). The imaginary line 322 indicating the width of the roof cloth equivalent blank 22 is a line drawn perpendicular to the longitudinal direction of the roof rail inner equivalent blank 21 from the intersection point of the outer edge (end face) of the roof cloth equivalent blank 22 in the direction perpendicular to the longitudinal direction (width direction) and the imaginary line 321 indicating the width of the roof rail inner equivalent blank 21.

[0057] Furthermore, when manufacturing integrated blanks for roof frame components, if all blank joints are joined (welded, etc.) before forming, the material flow during press forming is obstructed by the joints, introducing localized deformation. This not only worsens formability but can also cause cracking. Therefore, it is effective to perform joining (welding, etc.) in areas that do not obstruct material flow during press forming, or in areas with little material flow (for example, the blank corresponding to the top plate of the component) (i.e., to position the joints).

[0058] Hot press forming process: This is the process of hot press forming the obtained press forming blank (integrated blank). By press forming the press forming blank, a part or a part with a shape close to the part (near-net shape) can be obtained (the part obtained after the hot press process is called a press-formed product). The press forming method is not particularly limited, but generally, when obtaining large-dimensional and high-strength press-formed products (for example, a molded product made from a steel plate with a tensile strength of more than 590 MPa), hot press forming is preferable from the viewpoint of press load. Hot press forming is also called hot stamping (hot stamping method), and is a press forming method in which the blank (steel plate) is heated to the austenite temperature range of approximately 900°C, and then pressed and rapidly cooled at the same time to perform quenching by martensitic transformation. Hot press forming has the characteristics that the press load can be reduced because it is formed at a high temperature, and because martensitic transformation occurs during cooling, it has the characteristics of being high strength after forming while having excellent shape retention. For this reason it is often used when obtaining high-strength press-formed products.

[0059] Trimming process: The ancillary processes after press forming are not particularly limited. Examples include trimming and piercing processes. This is a process of refining the press-formed product (including parts that have been hot-press-formed and near-net-shape parts). The method of refining the press-formed product is not particularly limited. For example, it includes processing to remove burrs and excess material from the edges of the press-formed product using a laser to shape it to a predetermined shape (laser trimming). In addition, it includes a process of making holes to prevent paint liquid or rainwater from accumulating during painting (piercing process). Furthermore, in the case of near-net-shape press-formed products, it includes processing to create the final part shape. If a press-formed product with the final shape can be obtained by hot-press forming, this trimming process can be omitted.

[0060] Post-pressing parts joining process: In the process of forming an integrated blank for press forming, any overlapping sections that were not joined because they would hinder material flow during press forming may be joined (e.g., by welding) at this stage. Since the joining is done after press forming, material flow due to press forming has already occurred, so there is no introduction of deformation or cracking due to joining. Therefore, since the parts joined at this stage have not undergone heat treatment by hot pressing, the joints will have HAZ softening areas. In other words, in a roof frame part manufactured by integral press forming of an integrated blank according to this embodiment, at least one joint (a joint joined before hot stamping) among the joints of the overlapping sections of the blank will be a joint without HAZ softening. Since the remaining parts are joined after press forming, the roof frame part according to this embodiment will have both joints without HAZ softening and joints with HAZ softening. Furthermore, if it is necessary to join other parts to the obtained press-formed product, a process for joining them (post-press part joining process) may be provided.

[0061] The joining method herein is also not particularly limited. For example, joining may be performed by a joining method such as spot welding, arc welding, laser welding, or brazing. In addition, there are cases where a partial reinforcing material is attached to a press-formed product, or there are cases where parts that cannot be simultaneously formed by press forming are joined. Of course, when there is no need to join other parts, this post-press part joining step can be omitted.

[0062] Of the overlapping portions of the integrated blank, portions other than the joined portion (that is, unjoined portions) may be joined after press forming. This is because since it is after a complicated material flow has been completed, even if joining (welding) is performed at this stage, cracking will not be induced.

[0063] By going through these steps, the intended vehicle roof frame component can be finally obtained. Note that the manufacturing process of the component by press forming of the integrated blank is not limited to the steps described above. Other necessary steps can be added.

[0064] In the conventional technology, there was no concept of a roof frame component like that of the present embodiment. At least after blanking roof crosses, each is prepared through a trimming step after being individually pressed (such as hot press working), and then in the vehicle assembly step, each is individually joined (welded) and attached to the roof rail inner of the door ring. That is, at least as many press forming steps as the number of roof crosses are required. Even from this fact alone, it can be confirmed from the present example that according to the present embodiment, the number of press forming steps can be significantly reduced. Furthermore, according to the present embodiment, only one component management is required as a roof frame component, whereas in the conventional case, component management for the number of roof crosses is required, and it can also be confirmed from the present example that there is a cost reduction effect also from the viewpoint of management cost.

[0065] <Presence or absence of HAZ softened portion> Since the roof frame components obtained from the integrated blank are hot press-formed, the HAZ softened areas that formed before hot press-forming disappear due to the heat treatment during hot press-forming in the joints formed by welding such as spot welding and lap welding, friction stir welding, and friction pressure welding. In other words, in the components according to this embodiment, the joints of the overlapping parts of the blank that were joined (welded) before hot press-forming do not have HAZ softened areas. HAZ softening is a phenomenon in which the heat-affected zone (HAZ) in the base material just outside the outer edge of the weld metal in spot welding nuggets and arc welding is tempered and becomes softer than the base material. Similarly, in friction stir welding, friction pressure welding, and brazing, the softened area that forms in the heat-affected zone (HAZ) of the base material just outside the outer edge of the joint is the HAZ softened area. The disappearance of the HAZ softened area increases the strength of the joint, thus contributing to the improvement of the impact resistance performance of the finished component. In other words, since at least one of the joints of the roof frame component according to this embodiment does not have a HAZ softening area, the joint is strengthened compared to conventional components (components in which each roof cloth was joined together), and an improvement in the collision resistance performance of the component is expected. The following explanation will use resistance spot welding as an example.

[0066] Figure 9 shows an example of the correspondence between the results of a cross-sectional investigation of a spot-welded test piece 90 and the hardness distribution of the spot weld 91 and the base material 92 (steel plate corresponding to the blank). Unless otherwise specified, hardness refers to Vickers hardness. As can be seen in Figure 9, the spot weld 91 including the nugget 93 has a hardness of about Hv500 because it is hardened (since the hardness is almost the same within the spot weld, it is good to use the hardness at the center of the spot weld as a representative value). On the other hand, it can be seen that the hardness is softened to about Hv300 at a point about 1 mm away from the edge (outer edge) of the spot weld nugget 93 (near the outer edge of the spot weld). This softened area is the HAZ softening area. Normally, the HAZ softening area occurs in a region within 5 mm of the edge (outer edge) of the nugget or weld metal.

[0067] Further away from the nugget 93, the hardness converges to the hardness of the base material 92 (Figure 9 shows that it converges to a hardness of slightly less than Hv500). The hardness of the HAZ softened area relative to the center of the spot weld 91 is, for example, 50 Hv or more less when the base material 92 is a 1.0 GPa grade steel plate, 100 Hv or more less when it is a 1.5 GPa grade steel plate, and 150 Hv or more less when it is a 2.0 GPa grade steel plate. Generally speaking, if we define Hvm as the hardness of the base material 92, that is, the hardness of the base material 92 in the area unaffected by spot welding, and define the maximum hardness as the maximum value and the minimum hardness as the minimum value among the hardness measured within 5 mm from the end of the nugget outward (towards the base material), then ΔHv should be 0.2 Hvm or less, preferably 0.1 Hvm or less, when there is no HAZ softening. Conversely, if the HAZ is softening, ΔHv will exceed 0.2 Hvm.

[0068] The hardness distribution of the HAZ softened area can be determined by measuring the hardness (Vickers hardness) from the center of the spot weld outward along a straight line (hardness measurement line) parallel to the blank surface, at a position 3 / 4 of the way from the blank's surface (i.e., 1 / 4 of the way from the surface of the blank that is in contact with other blanks), in a cross section perpendicular to the surface (thickness direction cross section) that includes the center of the joint (center of the spot weld) on the surface of the outermost blank among the blanks that make up the overlapping section. It is preferable to measure the hardness distribution in the thickness direction cross section of the outermost blank among the blanks that make up the overlapping section. First, as the base material hardness (hardness of the base material in a part unaffected by the spot weld), measure the hardness at a position 15 mm or more away from the center of the spot weld and where no spot weld has been made, and define that hardness as Hvm. Specifically, the hardness is measured at 10 arbitrary points selected along the hardness measurement line, within a range of 15 mm to 25 mm from the center of the spot weld, where no spot welds have been made, and with a measurement interval (pitch) of 0.15 mm or more. The arithmetic mean of these 10 measurements is taken as the base material hardness Hvm. Note that the outermost blank here refers to the blank on the top surface when the press-formed part is placed with the convex shape facing upwards.

[0069] Next, the hardness is measured along the hardness measurement line, in a range of 5.0 mm from the outer edge (end) of the weld metal (nugget) outward (towards the base metal) at measurement intervals (pitch) of 0.15 to 0.25 mm. The maximum value of the measured hardness is taken as the maximum hardness, and the minimum value as the minimum hardness, allowing the difference ΔHv between the maximum and minimum hardness to be determined. This range allows the minimum hardness of the HAZ softened area due to spot welding to be captured. The outer edge of the weld metal (such as the outer edge of the spot weld) can be identified as the boundary between the spot weld and the base metal by the contrast created by etching the Vickers hardness measurement sample.

[0070] Vickers hardness is measured on a sample with the measurement plane containing the center of the weld metal (center of the spot weld) at x, in accordance with JIS Z 2244-1:2024, with a test force of 300 gf (2.942 N) and a holding time of 10 seconds.

[0071] Joints that do not have a HAZ softened area (spot-welded joints in the above description) are formed before hot press forming. That is, in the roof frame component according to this embodiment, at least one joint (spot-welded in the above description) in the overlapping area of ​​the roof cloth equivalent blank and the roof rail inner equivalent blank is a joint that does not have a HAZ softened area, meaning that the difference ΔHv between the maximum hardness and minimum hardness near the end of the joint is 0.2 times or less the hardness of the base material (0.2Hvm or less).

[0072] The hardness measurement of the HAZ softened area was explained using resistance spot welding as an example. For other joining methods, the same considerations apply as to resistance spot welding. For arc welding, the same applies as to resistance spot welding. For laser welding, the "weld metal" should be read as the molten metal portion, and for FSW and friction welding, the "weld metal" should be read as the agitated portion. For brazing, the "weld metal" should be read as the portion directly above the blank surface perpendicular to the brazed area. Furthermore, regarding the hardness measurement line, if the shape of the joint on the blank surface is point-shaped, for example, in the case of laser spot welding, it is best to measure the hardness by assuming a hardness measurement line, similar to resistance spot welding. If the shape of the joint on the blank surface is linear, for example, in the case of linear lap fillet welds or linear FSWs, it is best to measure the hardness by interpreting the cross section perpendicular to the joint line (weld line, etc.) as the "thickness direction cross section" and assuming a hardness measurement line.

[0073] This embodiment has been described through the examples above. As mentioned above, according to this embodiment, the number of press molding processes can be significantly reduced from the standpoint of production technology compared to the conventional method, and from the standpoint of parts management, the management burden is also significantly reduced because it only requires managing one part as a roof frame component, instead of managing each type of roof cloth as in the conventional method. [Industrial applicability]

[0074] This invention can be widely used in a wide range of industrial fields, including the transportation machinery industry (such as automobiles), the general machinery industry, and electrical equipment. [Explanation of symbols]

[0075] 100 Vehicle Frames (Automotive Frames) 101 Roof frame parts 11 Roof rail inner 111 Roof rail inner top panel 112 Roof rail inner wall section 113 Roof rail inner flange section 12 Roof Cross 121 Roof Cross Top Panel 122 Roof cross vertical wall section 123 Roof cross flange section 201 Integrated Blank 21 Roof rail inner equivalent blank 211 Roof rail inner equivalent blank top plate equivalent part 212 Roof rail inner equivalent blank vertical wall equivalent part 213 Roof rail inner equivalent blank flange section 22 Roof cloth equivalent blank 221 Roof cloth equivalent blank top plate equivalent part 222 Roof cloth equivalent blank vertical wall equivalent section 223 Equivalent to roof cross blank flange section 311 Dotted line indicating the width of the roof rail inner 312 Dotted lines indicating the width of the roof cross 321 Imaginary line indicating the width of the roof rail inner equivalent blank. 322 Imaginary line indicating the width of the roof cloth equivalent blank 31 Connection part 41. Overlapping parts 51 Joint 61 Bead 90 Spot Weld Test Pieces 91 Spot welds 92 Base material (blank) 93 Nuggets

Claims

1. A vehicle roof frame component that forms the roof portion of a vehicle and is made up of multiple steel plates joined together, The aforementioned vehicle roof frame component is, It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, The blank corresponding to the roof rail inner and the blank corresponding to the roof cloth have a joint where they are joined at the overlapping portion where they are superimposed on each other. A vehicle roof frame component characterized by the following features.

2. The vehicle roof frame component according to claim 1, wherein the joint portion is located in the overlapping portion of the connection portion where at least one roof rail inner and at least one roof cross are connected.

3. The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The vehicle roof frame component according to claim 2, wherein the connecting portion is connected such that the roof cross abuts against the vertical wall portion of the roof rail inner.

4. The overlapping portion is provided at least on the top plate portion of the roof rail inner, as described in claim 3 for a vehicle roof frame component.

5. A vehicle roof frame component according to any one of claims 1 to 4, wherein the roof cloth has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof cloth.

6. The roof frame component for a vehicle according to any one of claims 1 to 4, wherein the roof rail inner has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof rail inner.

7. The vehicle roof frame component according to any one of claims 1 to 4, wherein the vehicle roof frame component is a hot-stamped component.

8. The vehicle roof frame component according to any one of claims 1 to 4, wherein at least one of the aforementioned joints is a joint without a HAZ softening portion.

9. In the joint portion where the HAZ softening portion is absent, in a cross-section perpendicular to the surface of the outermost blank including the center of the joint portion, at a position 3 / 4 of the plate thickness from the surface of the outermost blank, When the Vickers hardness at a position 15 mm or more away from the center of the joint and not joined is Hvm, The vehicle roof frame component according to claim 8, wherein the difference between the maximum and minimum hardness in Vickers hardness, ΔHv, in a range of 5 mm or less from the end of the weld metal of the joint toward the base material is 0.2 Hvm or less.

10. The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The joint portion without the HAZ softening portion is present in one or both of the top plate portion of the roof rail inner and the top plate portion of the roof cloth, as described in claim 8.

11. A press-formed integrated blank configured as a joint structure for multiple steel plates for a vehicle roof frame component that constitutes the roof of a vehicle, The aforementioned vehicle roof frame component is, It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, The aforementioned integrated blank is It has two blanks corresponding to the roof rail inner that extend in the direction of vehicle travel, It has one or more blanks corresponding to a roof cross that are connected to the two blanks corresponding to roof rail inners, An integrated blank for a vehicle roof frame component, characterized in that at least one blank corresponding to the roof rail inner and at least one blank corresponding to the roof cloth have a joint portion joined at an overlapping portion where they are superimposed on each other.

12. The blank corresponding to the roof cloth comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The blank corresponding to the roof rail inner comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The integrated blank for a vehicle roof frame component according to claim 11, wherein the overlapping portion is arranged in at least the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner.

13. The integrated blank for a vehicle roof frame component according to claim 11 or 12, wherein the joint is a joint formed by resistance spot welding, laser spot welding, or overlap welding.

14. The joint portion is located in at least one of the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner and the portion corresponding to the top plate portion of the blank corresponding to the roof cloth, as described in claim 11 or 12.

Images