JP2009297775A - Manufacturing method of closed cross section metal member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suitably spot weld a superposed part of a center part of a workpiece when manufacturing a closed cross section metal member having two closed cross section parts extending in parallel with a recess groove interposed from a rectangular flat plate-like workpiece. <P>SOLUTION: Opposite edge parts S0, S0 of the rectangular flat plate-like workpiece W0 are notched to form an intermediate member W1 where a notched part m of one edge part and a non-notched part n of the other edge part are arranged to face with each other. The non-notched part n of the member W1 is folded back and the workpiece forms an intermediate member W2 where two-layer laminated parts A and single layer parts B are alternately arranged side by side at both edge parts S1, S2. The member W2 is folded to one surface side to gather both the edge parts S1, S2 of the member W2 to the center part of the member W2 and both the edge parts S1, S2 are folded to the other surface side. The center part of the member W2, the end part of the laminated part A of one edge part, and the end part of the single layer part B of the other edge part are superposed to form an intermediate member W3 so that the superposed part L of the member W3 is joined to form a final member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a closed cross-section metal member, and more particularly to a method for manufacturing a closed cross-section metal member having a structure having two closed cross-section portions extending in parallel across a concave groove from a rectangular flat plate-shaped workpiece. Belongs to the technical field.

  Conventionally, as a vehicle frame member or skeleton member such as a bumper reinforcement or a door impact beam, a flat metal member is spot-welded to a metal member that is hot stamped in a hat shape as shown in FIG. Thus, a metal tubular member is known in which a closed cross-sectional portion is formed to meet a high strength requirement.

  Further, as disclosed in, for example, Patent Document 1, a metal tubular member having a structure in which a rib for reinforcing strength is formed inside a pipe and the inside of the pipe is partitioned into two closed cross sections by the rib. It is.

JP-A-8-39177 (FIGS. 1 and 4)

  By the way, although the said patent document describes that the said closed cross-section metal member is manufactured by extrusion molding, generally two closed cross-section parts are not a rib but a ditch | groove by bending-molding a rectangular flat plate-shaped workpiece. It is possible to manufacture a closed cross-section metal member having a structure partitioned by a cross section, in other words, a closed cross-section metal member having a structure having two closed cross-section portions extending in parallel across a concave groove.

  That is, as illustrated in FIG. 14, a rectangular plate-shaped workpiece made of metal is used, and the workpiece is bent so that a pair of opposing edge portions of the workpiece are sequentially superimposed on the center portion of the workpiece (in the example shown in FIG. Fold or mountain fold), spot welding the overlapped portion (three sheets), a closed cross-section formed by bending one edge and a closed formed by bending the other edge It is possible to manufacture a closed cross-section metal member having a structure in which the cross-section portion is partitioned by the concave groove formed by the opposed surface portions of both closed cross-section portions and the overlapping portion.

  However, in this case, since the opposing surface portions of the both closed cross-sections constituting the concave groove are each a one-layer structure of the workpiece, there is a problem that the strength of the concave groove is insufficient.

  To solve this problem, as illustrated in FIG. 15, the pair of opposing edge portions of the workpiece do not end at the overlap portion at the center portion of the workpiece, but bend again and overlap the opposing surface portion of the counterpart closed cross-section portion. Thus, it is conceivable that the opposing surface portions of both closed cross-sectional portions constituting the concave groove have a two-layer structure of the workpiece.

  However, in this case, not only is it difficult to bend the workpiece so that the opposing surface portions of both closed cross-sections have a favorable two-layer structure at the opposite opposing edge portion, but the double-closed structure having this two-layer structure is also included. When spot-welding the facing surface portion of the cross-sectional portion, there is a problem that it is difficult to perform spot welding because the spot-welded portion is located in the closed cross-sectional portion.

  Therefore, as shown in FIG. 16, a pair of opposing edges of the workpiece are folded in advance to form a two-layer laminated portion and spot-welded in advance, and in this state, in the same manner as in FIG. It is conceivable to bend the workpiece. According to this, since the opposed surface portions of both closed cross-section portions are preliminarily made into a two-layer structure of the workpiece and are spot-welded, it is not necessary to superimpose a pair of opposed edge portions on the opposed surface portions of the counterpart closed cross-sectional portion. The above-mentioned problem that bending molding and spot welding of the closed cross section become difficult is solved.

  In FIG. 16, (front) indicates the edge that is first superposed on the work center, that is, the lower edge, and (rear) is the one that is superposed later on the work center, that is, on the top. The solid line spot welding indicates the pre-spot welding of the laminated part, the chain line spot welding indicates the spot welding to be performed after the overlapped part, and the plurality of parallel broken lines indicate the folding site. Show.

  However, in this case, as shown in an enlarged view in FIG. 16, the overlapped portion at the center portion of the workpiece is overlapped by five, so that a new problem arises that it becomes difficult to perform spot welding well.

  The present invention addresses the above-mentioned problems when manufacturing a closed cross-section metal member having a structure having two closed cross-sections extending in parallel across a concave groove from a rectangular flat plate-shaped workpiece. It is an object of the present invention to provide a method for producing a closed cross-section metal member that facilitates bending forming and spot welding of a closed cross-section while ensuring good welding, and is capable of satisfactorily spot-welding the overlap portion of the work center.

  In order to solve the above problems, the present invention uses the following means. In the disclosure of the following means, reference numerals corresponding to embodiments of the invention described later are added for reference.

  First, the invention described in claim 1 of the present application is a method of manufacturing a closed cross-section metal member T having two closed cross-section portions C1 and C2 extending in parallel with a concave groove G interposed therebetween from a rectangular flat plate workpiece W0. The pair of opposing edges S0, S0 of the workpiece W0 are cut out, and the notch m ... m of one edge S0 corresponds to the non-notch n ... n of the other edge S0. A first step of forming the first intermediate processed members W1 arranged in a row, the non-notched portions n... N of the first intermediate processed members W1 are folded back (F0), and two layers of workpieces are formed on both edges S1, S2. A second step of forming a second intermediate working member W2 in which laminated parts A ... A and single-layer parts B ... B are alternately arranged in parallel, both edges S1, of the second intermediate working member W2 The second intermediate working member W2 is bent toward one surface so that S2 is collected at the center of the second intermediate working member W2. F2, F3, F4) and the two edge portions S1, S2 are bent to the other surface side (F1), the central portion of the second intermediate processed member W2 and the laminated portion A of one edge portion A ... A end portion and the other A third step of forming the third intermediate processed member W3 in which the single layer portion B ... B end portion of the edge is superposed, and the overlapping portion L of the third intermediate processed member W3 are joined (P3) A fourth step of forming the final processed member T is included.

  Next, invention of Claim 2 of this application is a manufacturing method of the closed cross-section metal member of Claim 1, Comprising: In the said 2nd process, the notch part n ... n of one edge part And the non-notched portions n... N of the other edge are folded back to the opposite sides, and in the third step, the folded back of the non-notched portions n... N faces the central portion of the second intermediate workpiece W2. The end of the laminated portion A ... A of the edge S1 which is not present is superposed first, and the end of the laminated portion A ... A of the opposite edge S2 is superposed later.

  Next, invention of Claim 3 of this application is a manufacturing method of the closed cross-section metal member of the said Claim 1 or 2, Comprising: After the said 4th process, the last process member T is made into a length direction. The method further includes a fifth step of bending.

  Next, the invention according to claim 4 of the present application is the method for producing a closed cross-section metal member according to claim 3, wherein in the fifth step, the final processed member T can be plastically deformed and quenched. It is characterized in that it is hot-bended and hardened and quenched.

  Next, the invention according to claim 5 of the present application is the method for producing a closed cross-section metal member according to claim 4, and in the fifth step, the final processed member T is fixed to the fixing jig 12 and the movable jig. While being fed through the tool 15, the final processed member T is locally heated between the jigs 12, 15 to a temperature that can be plastically deformed and hardened (13), and the movable jig 15 is fixed to the fixed jig 12. The steel sheet is hot bent by being tilted with respect to the feeding direction, and quenched by quenching the heated portion immediately after the heating (14).

  Next, invention of Claim 6 of this application is a manufacturing method of the closed cross-section metal member of any one of the said Claim 1 to 5, Comprising: The said last process member T is a frame member of a vehicle. Or it is a skeleton member, It is characterized by the above-mentioned.

  First, according to the first aspect of the present invention, in the method of manufacturing the closed cross-section metal member T having the two closed cross-section portions C1 and C2 extending in parallel across the concave groove G from the rectangular flat plate workpiece W0, The pair of opposing edges S0 and S0 of the workpiece W0 are cut out, and the cutout portions m ... m on one edge portion and the non-cutout portions n ... n on the other edge portion are correspondingly arranged. The first intermediate working member W1 is formed, and then the non-notched portions n... N of the first intermediate working member W1 are folded back so that the workpieces are laminated on the two edges S1 and S2, and the laminated portions A. A second intermediate work member W2 in which single-layer portions B ... B are alternately arranged in parallel is formed, and the second intermediate work member W2 is bent and formed in the same manner as in FIGS. Therefore, the opposed surface portions H1 and H2 of the closed cross-section portions C1 and C2 constituting the concave groove G are respectively Since the single-layer structure B ... B and the two-layer structure A ... A are mixed, the number of sheets is larger than that of the single-layer structure alone, the strength of the groove G is ensured, and the edge S1 of the second intermediate workpiece W2 is secured. , S2 is partially formed into a two-layer laminated portion A ... A to facilitate bending and spot welding P1, P2 of the closed cross-section portions C1, C2, and superposition of the central portion of the second intermediate workpiece W2. The portion L is a four-layer stack of one sheet at the center of the second intermediate working member W2 and two sheets of the laminated part A ... A on one edge part and one sheet of the single-layer part B ... B on the other edge part. Since the number of sheets is smaller than the number of five sheets, spot welding P3 can be satisfactorily performed.

  Next, according to the invention described in claim 2, in consideration of the thickness of the folded back of the non-notched portions n... N, the polymerization is first performed in the overlapping portion L at the central portion of the second intermediate workpiece W2. The laminated portion A ... A of the edge S1 and the single layer B ... B of the edge S2 to be polymerized later face each other and the single layer B ... B of the edge S1 to be polymerized first and the edge to be polymerized later The laminated parts A ... A of the part S2 face each other, and the convex part of the laminated part A ... A and the concave part of the single layer part B ... B fit together, and as a result, the edges S1, S2 without applying force. The layers A and B are easily brought into close contact with each other, and the spot welding P3 of the overlapped portion L is further satisfactorily performed.

  Next, according to the invention described in claim 3, a product in which the final processed member T is bent in the length direction is manufactured. In this case, the opposing surface portions H1 and H2 of the closed cross-section portions C1 and C2 constituting the groove G extending in the length direction have a mixed structure of the one-layer structure B... B and the two-layer structure A. Therefore, as compared with the case where the entire surface has a two-layer structure, the bending resistance at the time of bending is reduced, and the advantage that the bending accuracy is improved can be obtained.

  Next, according to the fourth aspect of the present invention, the hot bending of the final processed member T and the quenching are performed simultaneously. In this case, the opposing surface portions H1 and H2 and the overlapping portion L of the closed cross-section portions C1 and C2 constituting the groove G extending in the lengthwise direction are less heated than the other portions in terms of shape. Since it is difficult to be cooled, the effect of improving the strength by quenching is small compared to the other parts, but the opposing surface portions H1, H2 of the closed cross-section portions C1, C2 constituting the groove G are each a one-layer structure of the workpiece. B ... B and a two-layer structure A ... A are mixed and the number of sheets is larger than that of only the one-layer structure, so that the strength of the groove G is ensured, and the overlapping portions L are overlapped by four. Since the strength of the concave groove G is ensured, the problem of insufficient strength due to the insufficient quenching is solved.

  Next, according to the fifth aspect of the present invention, push bending is applied as a bending method so that the final processed member T is locally heated, bent, and cooled. It is possible to perform hot bending and quenching well, surely and easily.

  Next, according to the invention described in claim 6, the frame member or the skeleton member of the vehicle having the characteristics of the invention described in any one of claims 1 to 5 is manufactured. Hereinafter, the present invention will be described in more detail through the best mode of the invention.

  FIG. 1 is a cross-sectional view showing the structure of a closed cross-section metal member T according to the present embodiment. The closed cross-section metal member T is a long tubular member having two closed cross-section portions C1 and C2 extending in parallel with the concave groove G interposed therebetween. In the figure, reference numerals H1 and H2 denote opposing surface portions of the closed cross-section portions C1 and C2 (or opposing surface portions of the groove G), reference character L denotes a superposed portion, and reference characters P1 to P3 denote spot weld portions.

  The said closed cross-section metal member T is manufactured using the rectangular flat plate-shaped workpiece | work W0 shown in FIG. First, in the first step, a pair of opposed edge portions S0, S0 of the rectangular flat workpiece W0 is cut out, and as shown in FIG. 3, a cutout portion m ... m of one edge portion S0, A first intermediate working member W1 is formed in which the non-notched portions (projecting piece portions) n... N of the other edge portion S0 are arranged correspondingly. In the figure, reference numeral F0 denotes a folded portion of the projecting piece portion n.

  Next, in the second step, the projecting piece portions n... N of the first intermediate processed member W1 are folded back at a folded portion F0, and as shown in FIG. 4, two layers of workpieces are laminated on both edge portions S1 and S2. A second intermediate processed member W2 is formed in which the portions A... A and the single-layer portions B. In that case, the protrusions n... N of the one edge S1 and the protrusions n... N of the other edge S2 are folded back to each other. Further, the two-layer laminated portions A ... A are spot welded P1, ... P1, P2, ... P2 in advance. In the figure, reference numerals F1 to F4 denote bent portions, (front) is the one that is superposed first at the center of the second intermediate workpiece W2, that is, the lower edge, and (rear) is the first 2 The one to be polymerized later at the center of the intermediate processed member W2, that is, the upper edge, the solid spot welds P1, P1, P2,... The spot welds P3... P3 are spot welds formed after the overlap portion L.

  Next, in the third step, the second intermediate working member W2 is bent to F2 and F3 so that the two edge portions S1 and S2 of the second intermediate working member W2 are gathered at the center of the second intermediate working member W2. , F4 bend one side (upper side in FIG. 4) (fold it in FIG. 1) and fold both edges S1 and S2 to the other side (lower side in FIG. 4) at the folding part F1. (Valley-folded in FIG. 1), the central portion of the second intermediate processed member W2 and the laminated portion A ... A end portion of one edge portion S1, and the single layer portion B ... B end portion of the other edge portion S2. Polymerized (at the same time, the middle part of the second intermediate processed member W2 and the single layer part B ... B end part of one edge part S1 and the laminated part A ... A end part of the other edge part S2 are polymerized) The processed member W3 is formed. In that case, as shown in FIG. 5 and FIG. 6, the end portion of the laminated portion A... A of the edge portion S 1 where the turn-up of the projecting piece portions n... N does not face the central portion of the second intermediate workpiece W 2. The ends of the laminated portion A... A of the facing edge S2 are polymerized later. In FIG. 6, for the sake of convenience, the boundary line between the upper and lower layers showing the two-layer structure of the stacked portions A... A is omitted (the same applies to FIG. 9).

  In the fourth step, the overlapped portion L of the third intermediate workpiece W3 is joined by spot welding P3... P3 to form the final workpiece T.

  7 corresponds to FIG. 4 and is a perspective view of the second intermediate working member W2 in the second embodiment. FIG. 8 corresponds to FIG. 5 and is an enlarged cross section of the overlapping portion at arrows iv and v in FIG. FIG. 9 and FIG. 9 are enlarged cross-sectional views of the overlapping portion taken along arrow vi in FIG. 8 corresponding to FIG.

  The second embodiment is the same as the first embodiment except that in the second step, the projecting pieces n... N of both edge portions S1, S2 are folded back to the same side. Further redundant explanation is omitted. As a result, as is apparent from FIG. 9, in the overlapped portion L at the center of the second intermediate workpiece W2, the laminated portions A ... A and the single layer portions B ... B of both edge portions S1, S2 may face each other. In addition, since the convex portion of the laminated portion A ... A and the concave portion of the single layer portion B ... B do not fit each other, the spot weld P3 of the overlapping portion L is applied with force to the edges S1, S2 or the layer A. , B are brought into close contact with each other.

  FIG. 10 is a perspective view showing the overall configuration of the hot bending apparatus 1 for the closed cross-section metal member T according to the preferred embodiment of the present invention.

  This hot bending apparatus 1 applies push-through bending as a bending technique, and has a closed cross-section metal member holding apparatus 10 that holds a terminal portion of a closed cross-section metal member T extending in the horizontal direction. The holding device 10 is configured to be movable on the track 11. In front of the holding device 10, fixed rollers 12 to 12, an induction heating coil 13, a cooling water injection device 14, and movable rollers 15 and 15 are arranged in this order from the upstream side.

  The fixing rollers 12... 12 as fixing jigs determine the feeding direction of the closed cross-section metal member T by sandwiching the closed cross-section metal member T from both sides in two stages.

  The induction heating coil 13 as a heating device has a shape surrounding the closed cross-section metal member T, and the closed cross-section metal member T is locally localized at a predetermined temperature in the surrounding range and its surroundings (the closed cross-section metal member T can be plastically deformed and quenched). Heat to possible temperature).

  The cooling water injection device 14 as a quenching device has a shape that surrounds the closed cross-section metal member T, and locally injects cooling water from the nozzle to the closed cross-section metal member T in the surrounding area and the periphery thereof. Quench quickly.

  The movable rollers 15 and 15 as movable jigs are accommodated in the housing 16 and sandwich the closed cross-section metal member T from both sides. And, it is movable in the same direction (x-axis direction) as the closed cross-section metal member feeding direction of the fixed rollers 12... 12, and is a direction orthogonal to the closed cross-section metal member feeding direction of the fixed rollers 12. (movable in the y-axis direction), movable in a direction (z-axis direction) perpendicular to the feeding direction of the closed cross-section metal member of the fixed roller 12 ... 12, rotatable around the y-axis, and around the z-axis It is configured to be freely rotatable. Then, by combining these movements, the movable rollers 15 and 15 are tilted with respect to the closed cross-section metal member feeding direction of the fixed rollers 12... 12, thereby applying a bending stress to the closed cross-section metal member T. The closed cross-section metal member T is bent in the length direction at a portion heated by the induction heating coil 13 (bending portion R as will be described later).

  The closed cross-section metal member T after being bent by the hot bending apparatus 1 or before being bent is a vehicle front side frame, rear side frame, bumper reinforcement, dash cross member, shot gun, roof side drain. It can be used for a frame member or a skeleton member of a vehicle such as a force.

  FIG. 11 is a control system diagram of the hot bending apparatus 1. The bending apparatus 1 includes a closed cross-section metal member feeding actuator 21 for moving the holding device 10 on a track 11 (in other words, feeding a closed cross-section metal member T), and the induction heating coil 13. The cooling water injection device 14 and the movable rollers 15 and 15 are rotated around the y axis and the z axis, and the actuators 22, 23, and 24 for moving the cooling rollers 15 and 15 in the x axis direction, the y axis direction, and the z axis direction. And a control unit 20 that outputs a control signal to the actuators 25 and 26 for controlling the hot bending operation of the closed cross-section metal member T performed by the bending apparatus 1.

  FIG. 12 shows (a), (b), (c), (d) a specific example of the hot bending process operation (fifth step) of the closed cross-section metal member T performed by the hot bending apparatus 1. It is process drawing shown in order of these.

  First, as shown in FIG. 12A, the closed cross-section metal member T is fed through the fixed rollers 12... 12 and the movable rollers 15 and 15. Then, along with the feeding, a predetermined bending portion (referred to as R) of the closed cross-section metal member T approaches the induction heating coil 13.

  Then, as shown in FIG. 12B, when the front end portion of the bending portion R enters the induction heating coil 13, the induction heating coil 13 is activated, and only the bending portion R is locally closed. The cross-section metal member T is heated to a temperature at which it can be plastically deformed and quenched (the portion with dots in the figure).

  Note that the determination that the front end of the bending portion R has entered the induction heating coil 13 is the position of the bending portion R registered in advance in a memory (not shown) of the control unit 20 in the closed cross-section metal member T, The determination is made based on the position of the induction heating coil 13 and the feeding speed of the closed cross-section metal member T. Alternatively, the front end portion of the bending portion R may be marked on the surface of the closed cross-section metal member T, and the marking may be detected directly with a sensor as appropriate.

  Then, when heating of the bending portion R by the induction heating coil 13 is started, the movable roller 15 is tilted with respect to the feeding direction of the closed cross-section metal member of the fixed roller 12 as shown in FIG. As a result, bending stress is applied to the closed cross-section metal member T, and the closed cross-section metal member T is bent at the portion heated by the induction heating coil 13, that is, the bending portion R.

  Moreover, as shown in FIG. 12C, when the heating of the bending portion R by the induction heating coil 13 is started and the bending processing by the movable roller 15 is started, the cooling water injection device 14 is activated and heated. The bent portion R that has been bent is locally cooled. Thereby, the bending process site | part R is quenched and the intensity | strength of the closed cross-section metal member T is raised simultaneously with a bending process.

  Then, as shown in FIG. 12 (d), after the rear end of the bending portion R comes out of the induction heating coil 13, the operation of the induction heating coil 13, the tilting of the movable roller 15, and the cooling water injection device 14. Is stopped, and the bending and quenching of the closed cross-section metal member T are completed.

  Note that the determination that the rear end portion of the bending portion R has come out of the induction heating coil 13 is also the position of the bending portion R registered in advance in the memory (not shown) of the control unit 20 in the closed cross-section metal member T. The determination is made based on the position of the induction heating coil 13, the feeding speed of the closed cross-section metal member T, and the like. Alternatively, the rear end portion of the bending portion R may be marked on the surface of the closed cross-section metal member T, and the marking may be directly detected by a sensor as appropriate.

  As described above, according to the first and second embodiments, a closed cross-section metal member T (see FIG. 1) having two closed cross-section portions C1 and C2 extending in parallel with the concave groove G interposed therebetween is used as a rectangular flat plate-like workpiece. In the method of manufacturing from W0 (see FIG. 2), first, a pair of opposed edge portions S0 and S0 of the workpiece W0 are cut out, and a cutout portion m... A first intermediate processed member W1 is formed in which the non-notched portions n... N are arranged correspondingly (see FIG. 3), and then the non-notched portions n... N of the first intermediate processed member W1 are folded back ( Folded part F0), the second intermediate workpiece W2 in which the laminated parts A ... A and the single-layer parts B ... B are alternately arranged in parallel on both edges S1, S2 is formed ( 4 and FIG. 7), and both the edge portions S1, S2 of the second intermediate processing member W2 are connected to the second intermediate processing member W2. The second intermediate working member W2 is bent to one surface side (folded portions F2, F3, F4) and the two edge portions S1, S2 are bent to the other surface side (folded portion F1). ), The middle portion of the second intermediate workpiece W2 and the laminated portion A ... A end of one edge and the single-layer portion B ... B end of the other edge form a third intermediate workpiece W3 formed by superposition. (Refer to FIGS. 5 and 6, 8 and 9), the opposing surface portions H1 and H2 of the closed cross-section portions C1 and C2 constituting the concave groove G are respectively a one-layer structure B ... B of the workpiece. Since the mixed structure with the two-layer structure A ... A is larger than the single-layer structure alone, the strength of the groove G is ensured, and the edges S1, S2 of the second intermediate workpiece W2 are partially divided into two layers in advance. The laminated part A ... A is made easy to bend and spot welds P1, P2 of the closed cross-section parts C1, C2, In addition, the overlapping portion L at the center of the second intermediate processing member W2 is composed of one sheet at the center of the second intermediate processing member W2 and two stacked portions A ... A at one edge and a single portion at the other edge. The layer part B ... 4 is overlapped with one sheet of B, and the number of sheets is less than the overlap of 5 sheets, so that spot welding P3 can be performed satisfactorily.

  In that case, according to the first embodiment, in consideration of the folded thickness of the non-notched portions n... N, the edge that is superposed first in the superposed portion L at the center of the second intermediate workpiece W2. The laminated portion A ... A of the part S1 and the single layer part B ... B of the edge S2 to be polymerized later face each other, and the single layer part B ... B of the edge S1 polymerized first and the edge S2 polymerized later The laminated portions A ... A are facing each other (see FIG. 6), and the convex portions of the laminated portions A ... A and the concave portions of the single layer portions B ... B fit together, and as a result, the edge portion without applying force. S1 and S2 or layers A and B are easily brought into close contact with each other, and spot welding P3 of the overlapped portion L is more satisfactorily performed.

  Moreover, according to 1st, 2nd embodiment, the product by which the last process member T was bent in the length direction will be manufactured (refer FIG. 10). In this case, the opposing surface portions H1 and H2 of the closed cross-section portions C1 and C2 constituting the groove G extending in the length direction have a mixed structure of the one-layer structure B... B and the two-layer structure A. Therefore, as compared with the case where the entire surface has a two-layer structure, the bending resistance at the time of bending is reduced, and the advantage that the bending accuracy is improved can be obtained.

  Moreover, according to 1st, 2nd embodiment, the hot bending process and hardening of the final process member T will be performed simultaneously (refer FIG. 10). In this case, the opposing surface portions H1 and H2 and the overlapping portion L of the closed cross-section portions C1 and C2 constituting the groove G extending in the lengthwise direction are less heated than other portions in terms of shape. Since it is difficult to cool (see FIG. 1), the effect of improving the strength by quenching is small compared to the other parts, but the opposed surface portions H1, H2 of the closed cross-section portions C1, C2 constituting the concave groove G are respectively Since the structure is a mixed structure of the one-layer structure B ... B and the two-layer structure A ... A of the workpiece, the number of sheets is larger than that of the one-layer structure alone. Since the strength of the concave groove G is ensured by overlapping, the problem of insufficient strength due to the insufficient quenching is solved.

  In addition, according to the first and second embodiments, push bending is applied as a bending method so that the final processed member T is locally heated, bent, and cooled (see FIG. 12). It becomes possible to hot-bend and quench the workpiece efficiently, reliably and easily.

  According to the first and second embodiments, the vehicle frame member or skeleton member having the characteristics of the invention according to any one of claims 1 to 5 is manufactured.

  The closed cross-section metal member T is not limited to a prismatic shape in which bending is performed at the portions F1 to F4, and may be a columnar shape having no creases (corners) or other shapes. Further, a tailored tube in which a plurality of different kinds of metal materials having different properties such as strength and plate thickness are connected may be used. Moreover, the use as a product of the closed cross-section metal member T is not limited to vehicle parts, but may be building materials or other uses.

  Further, the bending method is not limited to push-through bending, but may be rotary pull bending, compression bending, roll bending, press bending, tensile bending, or other methods.

  Further, the widths and intervals of the notches m... M or non-notches n. Furthermore, as long as five sheets are not stacked in the spot welded part P3 of the overlapped part L, the convex part of the laminated part A ... A and the concave part of the single layer part B ... B do not necessarily fit together.

  As described above in detail with reference to specific examples, the present invention provides a method for manufacturing a closed cross-section metal member having a structure having two closed cross sections extending in parallel with a concave groove therebetween from a rectangular flat work. Because it is a technique for providing a manufacturing method of a closed cross-section metal member that facilitates bending forming and spot welding of the closed cross section while ensuring the strength of the groove, and that can favorably spot weld the overlapped portion of the work center. Extensive industrial applicability is expected in the technical field of metalworking.

It is sectional drawing which shows the structure of the closed cross-section metal member which concerns on the best embodiment of this invention. It is a top view of the rectangular flat plate-shaped workpiece | work used for manufacture of the said closed cross-section metal member. It is a top view of the 1st intermediate processing member in the middle of manufacture of the above-mentioned closed section metal member. It is a perspective view of the 2nd intermediate processing member in the middle of manufacture of the above-mentioned closed section metal member in a 1st embodiment. It is an expanded sectional view of the superposition | polymerization part in the arrow i and ii of FIG. It is an expanded sectional view of the superposition | polymerization part in the arrow iii of FIG. It is a perspective view of the 2nd intermediate processing member in the middle of manufacture of the above-mentioned closed section metal member in a 2nd embodiment. It is an expanded sectional view of the superposition | polymerization part in the arrows iv and v of FIG. It is an expanded sectional view of the superposition | polymerization part in the arrow vi of FIG. It is a perspective view which shows the whole structure of the hot bending apparatus of the closed cross-section metal member which concerns on best embodiment of this invention. It is a control system figure of the said hot bending apparatus. It is process drawing which shows one specific example of the hot bending process operation | movement which the said hot bending apparatus performs in order of (a), (b), (c), (d). It is explanatory drawing of a prior art. It is explanatory drawing of another prior art. It is explanatory drawing of another prior art. It is explanatory drawing of another prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot bending processing apparatus A of a closed cross-section metal member Lamination | stacking part B Single layer part C1, C2 Closed cross-section part F0 Folding site | part F1-F4 Folding site | part G Concave groove L Overlapping part m Notch part n Notch part Part)
P1-P3 Spot welded portion S0 Opposite edge portions S1, S2 of rectangular flat plate workpieces Both edge portions T of second intermediate processed member Closed cross-section metal member, final processed member W0 Rectangular flat plate workpiece W1 First intermediate processed member W2 Second Intermediate processing member W3 Third intermediate processing member

Claims (6)

A method of manufacturing a closed cross-section metal member having two closed cross-sections extending in parallel across a concave groove from a rectangular flat work,
A first step of forming a first intermediate working member in which a pair of opposed edge portions of the workpiece is cut out, and a cutout portion of one edge portion and a non-cutout portion of the other edge portion are aligned in correspondence. ,
The non-notched portion of the first intermediate processing member is folded back to form a second intermediate processing member in which two layers of laminated portions and one single layer portion are alternately arranged on both edges. Second step,
The second intermediate working member is bent to one surface side and the both edge portions are bent to the other surface side so that the both edge portions of the second intermediate processing member are collected in the central portion of the second intermediate processing member. A third step of forming a third intermediate processing member in which the central portion of the second intermediate processing member, the laminated portion end of one edge and the single layer end of the other edge are superposed, and
A method for producing a closed cross-section metal member, comprising a fourth step of forming a final processed member by joining the overlapping portions of the third intermediate processed member. It is a manufacturing method of the closed section metal member according to claim 1,
In the second step, the non-notched portion of one edge and the non-notched portion of the other edge are folded back to the opposite sides,
In the third step, the end portion of the laminated portion of the edge portion facing the center portion of the second intermediate processing member is overlapped with the end portion of the non-notched portion, and the end portion of the laminated portion of the opposite edge portion. A method for producing a closed cross-section metal member, characterized in that the following is polymerized. It is a manufacturing method of the closed section metal member according to claim 1 or 2,
After the fourth step, the method further includes a fifth step of bending the final processed member in the length direction. It is a manufacturing method of the closed section metal member according to claim 3,
In the fifth step, a method for producing a closed cross-section metal member, wherein the final processed member is heated to a plastically deformable and quenchable temperature, hot-bended, and quenched. It is a manufacturing method of the closed section metal member according to claim 4,
In the fifth step, while the final processed member is fed through a fixed jig and a movable jig, the final processed member is locally heated between the two jigs to a temperature that can be plastically deformed and hardened, and is movable. A method for producing a closed cross-section metal member, wherein the jig is hot-bent by tilting the jig with respect to the feeding direction of the fixed jig, and quenched by quenching the heated portion immediately after the heating. It is a manufacturing method of the closed section metal member according to any one of claims 1 to 5,
The method of manufacturing a closed cross-section metal member, wherein the final processed member is a frame member or a skeleton member of a vehicle.

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