JP2011098370A - Method for manufacturing metallic closed-section member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metallic closed-section member capable of suitably forming a plate-like workpiece so as to have a closed-section. <P>SOLUTION: The method for manufacturing the metallic closed-section member includes: a first molding step of press-molding the plate-like workpiece into a protruded shape, and molding a protrusion W2a protruded in an opposite direction at a top face part W2 when manufacturing the closed-section member from the plate-like workpiece W1; a second molding step of press-molding the protrusion in an opposite direction to a protruding direction to crush the protrusion by a punch 65 while the plate-like workpiece is held at a die 61, and bringing end parts W3e, W4e of side face parts into contact with both the side faces 65d, 65c of the punch while the side face parts W3, W4 at both the sides are displaced to an inner side to be urged to the inner side of the plate-like workpiece; and a third molding step of extracting the punch from the plate-like workpiece so as to have the closed-section. The second molding step is carried out using the die having a recess 63 at a portion corresponding to a crushed part W2d formed by crushing the protrusion of the plate-like workpiece at the surface of the die. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a metal closed cross-section member that manufactures a closed cross-section member formed in a closed cross-section shape from a metal plate-shaped material (plate-shaped workpiece).

  As is well known, body members such as pillar members that form part of the basic structure of a vehicle body in a vehicle such as an automobile, front and rear side frames, and a dash cross member that is located in the lower front portion of a dash panel include: From the viewpoint of ensuring strength and rigidity and improving safety, high strength and high rigidity are required, and weight reduction is required for improving fuel efficiency.

  In order to meet these demands, the vehicle body member as described above is often configured as a metal closed cross-section member. As a method of manufacturing this metal closed cross-section member, for example, a metal plate-like workpiece such as a steel plate is formed into a cross-sectional hat shape integrally formed with flange portions projecting outward at both ends of a U-shaped cross section by pressing, There is generally known a method of manufacturing a closed cross-section member by superimposing the flange portions of two plate-like workpieces formed in a cross-sectional hat shape to form a closed cross-section shape and then welding the flange portions.

  In the case where the flange portions of two plate-like workpieces formed in a cross-sectional hat shape are overlapped with each other, the weight is reduced by the flange portions provided on both sides of the closed cross-sectional member used only for manufacturing the closed cross-sectional member. Since it is obstructed and the number of welded portions that weld the flange portion increases, a method of manufacturing a closed cross-section member from a single plate-like workpiece is also known as a method for improving this.

  As a method for manufacturing a closed cross-section member from a single plate-shaped workpiece, for example, Patent Document 1 discloses that the edges of the three sides of both sides and the rear end of a substantially rectangular metal plate are left as flange portions and front and rear in the middle of the left and right sides. A first step of drawing the two left and right recesses separated by the ridge so as to form a ridge extending in the direction, and between the fixed part and the punch so as to form a bottom by crushing the ridge portion. A second step of bending the left and right half portions of the metal plate until the flange portion is abutted in the direction in which the opening of the concave portion faces, while drawing, and a third step of welding the flange portion that has been abutted A method for producing a hollow plate for heat absorption comprising a process is disclosed.

  Further, for example, in Patent Document 2, a process of manufacturing a semi-finished product in which a pair of closed cross-section structure halves are raised from both ends of a connection section having a flat cross-section by pressing a metal plate, and a double-close cross-section structure A step of further raising both closed cross-section structure halves while pressing the connecting portion from the inside by a flat punch inserted between the half halves to form a bent portion protruding outward in a V-shaped cross section; A method of manufacturing a closed cross-section structure is disclosed in which a flat punch is pulled up from between the cross-section structure halves and then the outer ends of both closed cross-section structure halves are brought into contact with each other and welded sequentially.

JP-A-53-65257 JP 2006-116552 A

  However, when the method disclosed in Patent Document 1 is applied to the manufacture of a vehicle body member having a complicated closed cross-sectional shape, drawing is performed between the fixed portion and the punch in order to make the closed cross-section. It is necessary to make a fixing portion and a punch having the same shape as the closed cross-sectional shape, and it can be difficult to apply to the manufacture of a vehicle body member having a complicated closed cross-sectional shape.

  In contrast, according to the method disclosed in Patent Document 2, the connecting portion is pressed from the inside by a flat punch inserted between a pair of closed cross-section structure halves rising from both ends of the connecting portion having a flat cross section. The two closed cross-section structure halves are raised while forming a bent portion protruding outward in a V-shaped cross section, and the flat punch is pulled up between the two closed cross-section structure halves. Since the outer ends are brought into contact with each other to form a closed section, the present invention can be applied to the production of a vehicle body member having a complicated closed section shape.

  However, when a flat punch is pressed from the inside by a flat punch to rise to the outside in a V-shaped cross section and both closed cross-section structure halves rise to a closed cross section, when the flat punch is pulled up, In some cases, the outer ends of the two closed cross-section structure halves cannot be brought into contact with each other by the spring back. In such a case, it is necessary to press the two closed cross-section structure halves from the outer side.

  Therefore, the present invention has been made in view of the above technical problem, and suppresses the occurrence of springback when a closed cross-section member is manufactured from a metal plate-like workpiece, thereby satisfactorily closing the plate-like workpiece. It aims at providing the manufacturing method of the metal closed cross-section member which can be made into a cross section.

  For this reason, the manufacturing method of the metal closed cross-section member according to claim 1 of the present application presses the metal plate-shaped workpiece into a convex shape and forms the plate on the top surface portion formed into the convex shape of the plate-shaped workpiece. A first forming step of forming a convex portion projecting in a direction opposite to the convex projecting direction of the shaped workpiece, and the convex portion in a direction opposite to the projecting direction by a punch while holding the plate-shaped workpiece on the die By pressing, the convex portion is crushed and the side portions on both sides of the top surface portion are respectively displaced inward to be urged toward the inward side of the plate-like workpiece. A second molding step in which the punches are brought into contact with both side surfaces of the punch, and the punches are extracted from the plate-like workpiece in a state where the end portions of the side surfaces on both sides are in contact with both side surfaces of the punch, respectively. Displace the part further inward to move the plate-like work A third forming step of making a cross-section, a method of manufacturing a metal closed cross-section member, wherein the second forming step corresponds to a crushing portion of a convex portion of the plate-like workpiece on the surface of the die This is performed using a die provided with a recess.

  The invention according to claim 2 of the present application is characterized in that, in the invention according to claim 1, the concave portion provided in the die is formed in a cross-sectional curve shape or a cross-sectional angle shape. .

  Furthermore, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, and is opposite to the top surface portion side of the side surface portion of the plate-like workpiece between the first forming step and the second forming step. The method further comprises a bending step of bending the end portion on the side toward the inward side of the plate-like workpiece.

  Still further, the invention according to claim 4 of the present application is the invention according to any one of claims 1 to 3, wherein the end of the side surface portion of the plate-like workpiece having a closed cross section is formed after the third forming step. The method further includes a welding step of welding the parts together.

  According to the manufacturing method of the metal closed cross-section member according to claim 1 of the present application, the convex portion at the top surface portion of the plate-like workpiece formed in the first forming step is crushed by the punch in the second forming step. In the state where the side surface portion of the workpiece is displaced inward and urged toward the inner side of the plate workpiece, the end portions of the side surface portions are brought into contact with both side surfaces of the punch, and the punch is formed in the third molding step. Since it is extracted from the plate-like workpiece, the side portions on both sides of the plate-like workpiece are further displaced inward, and the plate-like workpiece is closed.

  At that time, the deformation when the convex part is crushed by performing the second molding step using a die provided with a concave part in a portion corresponding to the convex part of the convex part of the plate-like workpiece on the surface of the die. Increase the amount to increase the urging force that the side part of the plate-like workpiece urges inward of the plate-like workpiece, so it is possible to suppress the occurrence of springback when the punch is removed from the plate-like workpiece. It is possible to satisfactorily match the end portions of the side surfaces of the plate-like workpiece, and to make the plate-like workpiece have a good closed cross section. The closed cross-section member can be satisfactorily manufactured from the plate-shaped workpiece without separately providing a step of pressing the side surface portion of the plate-shaped workpiece from the outside in order to make the plate-shaped workpiece closed. Furthermore, in the method disclosed in Patent Document 2, it is necessary to form a bent portion that protrudes outward in order to obtain a closed cross section, the shape of the closed cross section member is limited, and the portion pressed by the punch is flat. Although a closed cross-section member cannot be manufactured, according to the invention of the present application, a closed cross-section member having a flat portion pressed by a punch is manufactured without limiting the shape of the closed cross-section member to make a closed cross-section. be able to.

  Moreover, according to the invention which concerns on Claim 2 of this application, the said effect can be implement | achieved more concretely by the recessed part provided in die | dye being formed in cross-sectional curve shape or cross-sectional angle | corner shape.

  Furthermore, according to the invention which concerns on Claim 3 of this application, the edge part on the opposite side to the top surface part side of the side part of a plate-shaped workpiece is inward of a plate-shaped workpiece between a 1st shaping | molding process and a 2nd shaping | molding process. By further comprising a bending process for bending to the side, when the side portions on both sides are displaced inward, the displacement of the side portions to the inward side is reduced and the closed cross-section member is more accurately Can be manufactured.

  Furthermore, according to the invention according to claim 4 of the present application, after the third forming step, by further comprising a welding step of welding the end portions of the side surface portions of the plate-like workpiece having a closed cross section, The joint strength of the closed cross-section member can be increased, and a stronger closed cross-section member can be manufactured.

It is a side view showing typically the body structure of a car provided with the metal closed section member concerning this embodiment. It is a perspective view showing roughly a front side frame as a metal closed section member concerning this embodiment. FIG. 3 is a cross-sectional view schematically showing a front side frame taken along lines Y3a-Y3a and Y3b-Y3b in FIG. It is a perspective view which shows the press-molding die of the 1st press-molding apparatus for press-molding a plate-shaped workpiece. It is sectional drawing of the press-molding die along the Y5-Y5 line in FIG. It is explanatory drawing for demonstrating the press molding process by a 1st press molding apparatus. It is a perspective view which shows the plate-shaped workpiece press-molded by the 1st press molding apparatus. It is sectional drawing of the plate-shaped workpiece along the Y8-Y8 line | wire in FIG. It is sectional drawing which shows the bending mold of the bending apparatus for bending the edge part of the side part of a plate-shaped workpiece. It is explanatory drawing for demonstrating a bending process. It is explanatory drawing for demonstrating a bending process. It is sectional drawing which shows the press molding die of the 2nd press molding apparatus for press-molding the convex part of a plate-shaped workpiece. It is explanatory drawing for demonstrating the press molding process by a 2nd press molding apparatus. It is explanatory drawing for demonstrating the press molding process by a 2nd press molding apparatus. It is explanatory drawing for demonstrating the press molding process by a 2nd press molding apparatus. It is sectional drawing which shows another press molding die of the 2nd press molding apparatus for press-molding the convex part of a plate-shaped workpiece.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, it means a specific direction such as “up”, “down”, “right”, “left” and other terms including them, “clockwise direction”, “counterclockwise direction”, etc. The terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of the terms.

  FIG. 1 is a side view schematically showing a vehicle body structure of an automobile provided with a metal closed cross-section member according to the present embodiment. In the present embodiment, as a metal closed cross-section member that is manufactured by forming a metal plate-like workpiece into a closed cross-section, a front side frame 20 coupled to a side body 10 of an automobile as shown in FIG. 1 is taken as an example. Although described, the present invention is not limited to this, and may be applied to other vehicle body members formed in a closed cross-sectional shape such as the rear side frame 30 coupled to the side body 10, and is not limited to the vehicle body members. It is also possible to apply to other metal closed cross-section members formed in a closed cross-section.

  FIG. 2 is a perspective view schematically showing a front side frame as a metal closed cross-section member according to the present embodiment. 3 is a cross-sectional view schematically showing the front side frame along the Y3a-Y3a line and the Y3b-Y3b line in FIG. 2, and FIG. 3 (a) shows the Y3a-Y3a line in FIG. FIG. 3B is a cross-sectional view schematically showing the front side frame along the line Y3b-Y3b in FIG. 2.

  As shown in FIG. 2, the front side frame 20 as a metal closed section member according to the present embodiment is configured as a closed section member that extends in the longitudinal direction and is formed in a closed section shape, The lower surface portion 22, the right side surface portion 23, the left side surface portion 24, the first inclined side surface portion 25 that is inclined obliquely downward to the right from the upper surface portion 21 toward the right side surface portion 23, and the upper surface portion 21 toward the left side surface portion 24. A second inclined side surface portion 26 inclined obliquely downward to the left, a third inclined side surface portion 27 inclined obliquely upward and rightward from the lower surface portion 22 toward the right side surface portion 23, and from the lower surface portion 22 toward the left side surface portion 24. Thus, the fourth inclined side surface portion 28 inclined obliquely upward to the left is formed into a substantially octagonal cross section having a hollow portion 29.

  As shown in FIG. 2, the front side frame 20 has an upper surface portion 21 and a lower surface portion 22 formed substantially in parallel along the longitudinal direction and substantially the same cross-sectional length in the short direction. The cross-sectional shape is changed in the longitudinal direction. In the cross section shown in FIG. 3A, the front side frame 20 includes a left side surface portion 24, a first inclined side surface portion 25, and a third inclined side surface portion 27, the left side surface portion 24 in the cross section shown in FIG. The right inclined surface portion 23, the second inclined side surface portion 26, and the fourth inclined surface are formed so as to have shorter cross-sectional lengths than the first inclined side surface portion 25 and the third inclined side surface portion 27. The side surface portion 28 is formed to have a cross-sectional length longer than the cross-sectional lengths of the right side surface portion 23, the second inclined side surface portion 26, and the fourth inclined side surface portion 28 in the cross section shown in FIG. ing.

  Further, in the front side frame 20, the inclination angle of the third inclined side surface portion 27 with respect to the lower surface portion 22 and the inclination angle of the fourth inclined side surface portion 28 with respect to the lower surface portion 22 are each formed at a constant predetermined angle in the longitudinal direction. The right side surface portion 23 and the first inclined side surface portion 25 are formed with a plurality of beads 31 recessed inward of the hollow portion 29.

Next, a method for manufacturing the front side frame 20 as a metal closed cross-section member according to this embodiment configured as described above will be described.
In this embodiment, when manufacturing the front side frame 20, first, a rectangular metal plate material (plate workpiece) formed in a substantially flat plate shape such as a steel plate is prepared, and this plate workpiece is used. It is press-molded into a convex shape, specifically, drawn (drawn), and shaped into a predetermined shape corresponding to the shape of the front side frame 20.

  4 is a perspective view showing a press forming die of a first press forming apparatus for press forming a plate-like workpiece, and FIG. 5 is a first press forming apparatus taken along line Y5-Y5 in FIG. It is sectional drawing of the press-molding die. In FIG. 4, the concave portion provided on the lower surface of the die of the press mold and the punch provided in the blank holder of the press mold are shown by solid lines, and FIG. 5 also shows a plate-like work held by the blank holder. ing.

  As shown in FIGS. 4 and 5, the first press forming apparatus for press forming the plate-like workpiece W1 presses the plate-like workpiece W1 into a convex shape and is formed into a convex shape of the plate-like workpiece W1. A die 45 and a punch 42 for forming a convex portion projecting in a direction opposite to the convex direction of the plate-like workpiece W1 on the top surface portion, and the die 45 and the punch 42 that are relatively moved, and a plate There is provided a press mold (first press mold) 40 having a blank holder 41 for sandwiching the workpiece W1 with a die 45.

  The die 45 of the press mold 40 is provided with a recess 45b that is recessed in the lower surface 45a, and a molding space 45c for press-molding the plate-like workpiece W1 is formed in the recess 45b. The concave portion 45b provided in the die 45 is formed in a predetermined shape according to the shape of the front side frame 20, and has a bottom surface portion 45d formed in a substantially flat shape, and a first inclination inclined obliquely downward to the right from the bottom surface portion 45d. A wall portion 45e, a right vertical wall portion 45f extending vertically downward from the first inclined wall portion 45e, a second inclined wall portion 45i inclined obliquely downward to the left from the bottom surface portion 45d, and a second inclined wall portion And a left vertical wall portion 45j extending vertically downward from 45i. In addition, the bottom surface 45d of the recess 45b is provided with a convex portion 45m that protrudes in a circular arc shape from the bottom surface 45d toward the inside of the molding space 45c. The convex portion 45m is formed as shown in FIG. The bottom surface 45d is provided continuously in the longitudinal direction.

  The punch 42 of the press mold 40 has the outer peripheral surface portion 42 a fitted into the inner peripheral surface portion 41 a of the blank holder 41, is moved in the vertical direction by a punch moving mechanism (not shown), and is moved relative to the die 45. It is like that. The punch 42 is formed in a predetermined shape according to the shape of the front side frame 20 in order to press-mold the plate-like workpiece W1 with the die 45, and the head of the punch 42 is formed in a substantially flat shape. 42 d of upper surface parts, the 1st inclination wall part 42e which inclines to the right diagonally downward from the upper surface part 42d, and the right vertical wall part which extends in the perpendicular direction downward from the 1st inclination wall part 42e, and comprises a part of outer peripheral surface part 42a 42f, a second inclined wall portion 42i inclined obliquely downward to the left from the upper surface portion 42d, and a left vertical wall portion 42j extending vertically downward from the second inclined wall portion 42i and constituting a part of the outer peripheral surface portion 42a, It has. The upper surface portion 42d of the punch 42 is provided with a concave portion 42m that is recessed from the upper surface portion 42d in a circular arc shape, and the concave portion 42m is provided continuously in the longitudinal direction on the upper surface portion 42d.

  The blank holder 41 of the press mold 40 is for holding the plate-like workpiece W1 against the die 45, and is illustrated so as to hold the plate-like workpiece W1 with the die 45 while holding the plate-like workpiece W1. The blank holder moving mechanism is not moved up and down.

  The first press molding apparatus includes a first press molding apparatus control unit (not shown) for comprehensively controlling the first press molding apparatus, and for the first press molding apparatus. The control unit controls various operations such as a mechanism for moving the punch 42 and the blank holder 41. The first press molding apparatus control unit, and the second press molding apparatus control unit and the bending molding apparatus control unit, which will be described later, are configured with, for example, a microcomputer as a main part.

  In the first press molding apparatus including the press mold 40 configured as described above, the punch 42 is placed in the molding space 45c of the die 45 in a state where the plate-like workpiece W1 is sandwiched between the blank holder 41 and the die 45. The plate-like workpiece W1 is press-molded into a predetermined shape in accordance with the shape of the front side frame 20 by moving the plate to the plate-like workpiece W1. The die 45 has a bead-forming projecting portion (not configured) that projects toward the inner side of the molding space 45c in accordance with the shape of the bead 31 on the second inclined wall portion 45i and the left vertical wall portion 45j of the recess 45b. In the punch 42, a bead forming groove (not shown) is formed in the second inclined wall portion 42i and the left vertical wall portion 42j. The bead forming groove portion is recessed in accordance with the shape of the bead 31.

  When the plate-like workpiece W1 is press-molded using the first press-molding apparatus, as shown in FIG. 5, the blank holder 41 and the die 45 are spaced apart from each other, and the upper surface portion 42d of the punch 42 is blank. The plate-like workpiece W <b> 1 is held by the upper surface portion 41 b of the blank holder 41 in a state of being disposed below the upper surface portion 41 b of the holder 41. Then, the blank holder 41 of the press mold 40 is moved upward, the both ends in the short direction of the plate-like workpiece W1 are clamped by the blank holder 41 and the die 45, and then the punch 42 is moved upward, 42 is moved into the molding space 45c of the die 45, and the plate-like workpiece W1 is press-molded.

  FIG. 6 is an explanatory view for explaining a press forming process by the first press forming apparatus. FIG. 6A shows a state in which the punch moves upward after the plate-like workpiece is sandwiched between the blank holder and the die. FIG. 6B shows a state where the punch is further moved upward and the plate-like workpiece is further press-molded.

  As shown in FIG. 6A, the punch 42 is moved into the molding space 45c of the die 45 in a state where the plate-like workpiece W1 is sandwiched between the blank holder 41 and the die 45, whereby the upper surface portion of the punch 42 is obtained. The plate-like workpiece W1 is press-formed into a trapezoidal cross section by 42d. When the punch 42 is further moved upward, as shown in FIG. 6B, the plate-like workpiece W1 is further press-formed, and the plate-like workpiece W1 is formed into a predetermined shape by the punch 42 and the die 45.

  FIG. 7 is a perspective view showing a plate-like workpiece press-formed by the first press-forming apparatus, and FIG. 8 is a cross-sectional view of the plate-like workpiece taken along line Y8-Y8 in FIG. As shown in FIGS. 7 and 8, the plate-like workpiece W <b> 1 has a central portion in the short-side direction with respect to the die 45 except for both ends in the short-side direction of the plate-like workpiece W <b> 1 sandwiched between the blank holder 41 and the die 45. The punch 42 is protruded in the moving direction and press-molded into a convex shape, and has a top surface portion W2 and side surface portions W3 and W4 on both sides of the top surface portion W2.

  The press-formed plate-like workpiece W1 has a top surface portion W2 formed by a bottom surface portion 45d of a recess 45b provided in the die 45 and an upper surface portion 42d of the punch 42, and the top surface portion W2 is provided on the bottom surface portion 45d. Convex portions W2a projecting in a circular arc shape in a direction opposite to the projecting shape of the plate-like workpiece W1 are provided continuously in the longitudinal direction by the convex portions 45m and the concave portions 42m provided on the upper surface portion 42d. . Further, as shown in FIG. 7, the top surface portion W2 is divided by the convex portion W2a into a right top surface portion W2b located on the right side of the convex portion W2a and a left top surface portion W2c located on the left side of the convex portion W2a. The portions W2b and W2c divided by the convex portion W2a of W2 are shaped so that the cross-sectional length in the short direction changes in the longitudinal direction.

  On the right side of the top surface portion W2, a side surface portion is formed by the first inclined wall portion 45e and the right vertical wall portion 45f of the recess 45b provided in the die 45 and the first inclined wall portion 42e and the right vertical wall portion 42f of the punch 42. W3 is formed, and the side surface portion W3 is formed by the first inclined wall portion 45e of the recess 45b and the first inclined wall portion 42e of the punch 42, and is inclined obliquely downward to the right from the right top surface portion W2b of the top surface portion W2. The first right side W3a has a second right side W3b formed by the right vertical wall 45f of the recess 45b and the right vertical wall 42f of the punch 42 and extending vertically downward from the first right side W3a. is doing.

  On the other hand, on the left side of the top surface W2, the second inclined wall 45i and the left vertical wall 45j of the recess 45b provided in the die 45 and the second inclined wall 42i and the left vertical wall 42j of the punch 42 are provided. The side surface portion W4 is formed, and the side surface portion W4 is formed by the second inclined wall portion 45i of the recess 45b and the second inclined wall portion 42i of the punch 42, and is obliquely lower left from the left top surface portion W2c of the top surface portion W2. A second left side W4b formed by the inclined first left side W4a, the left vertical wall 45j of the recess 45b and the left vertical wall 42j of the punch 42 and extending vertically downward from the first left side W4a. Have.

  The press-formed plate-like workpiece W1 also includes the second inclined wall portion 45i of the recess 45b and the second inclined wall portion 42i of the punch 42 and the second inclined wall portion 42i of the punch 42 formed on the left vertical wall portion 45j. The bead forming groove formed in the left vertical wall 42j forms a bead W4f on the side surface W4, specifically, the first and second left side surfaces W4a and W4b.

  Further, the convex portion W2a, the right top surface portion W2b, and the left top surface portion W2c provided on the top surface portion W2 are the shapes of the lower surface portion 22, the fourth inclined side surface portion 28, and the third inclined side surface portion 27 of the front side frame 20, respectively. The first right side W3a of the side surface W3 is molded according to the shape of the left side 24 of the front side frame 20, and the second right side W3b of the side W3 is the second side of the front side frame 20. 2 is formed in accordance with the shape of the inclined side surface portion 26 and the upper surface portion 21, and the first left side surface portion W4a of the side surface portion W4 is formed in accordance with the shape of the right side surface portion 23 of the front side frame 20, and Two left side surfaces W4b are formed according to the shapes of the first inclined side surface portion 25 and the upper surface portion 21 of the front side frame 20.

  In the present embodiment, the punch 42 is moved into the molding space 45c of the die 45 while the plate-like workpiece W1 is sandwiched between the blank holder 41 and the die 45. You may make it press-mold by moving the blank holder 41 and the die | dye 45 which clamped the workpiece | work W1 relatively with respect to the punch 42. FIG.

  After the plate-like workpiece W1 is press-molded by the first press molding apparatus having the press-molding die 40 in this way, the press-molded plate-like workpiece W1 is shown in FIG. 8 by blanking means (not shown). A portion located below the blanking line L1 is blanked, and both end portions W5 in the short direction of the plate-like workpiece W1 sandwiched between the blank holder 41 and the die 45 are cut off.

  Next, the plate-like workpiece W1 has end portions W3e, W4, specifically, end portions W3e opposite to the top surface portion W2 side of the second right side surface portion W3b of the side surface portions W3 shown in FIG. And the end W4e opposite to the top surface W2 side of the second left side W4b of the side W4 is bent inward. FIG. 9 is a cross-sectional view showing a bending mold of a bending apparatus for bending an end portion of a side surface portion of a plate-like workpiece press-formed by the first press-forming apparatus.

  As shown in FIG. 9, the bending apparatus for bending the end portions W3e, W4e opposite to the top surface portion W2 side of the side surface portions W3, W4 of the plate workpiece W1 to the inward side of the plate workpiece W1 is as shown in FIG. The first die 51 for holding the plate-like workpiece W1 press-formed in a convex shape, the second die 52 fitted to the outer peripheral surface 51a of the first die 51, and the second die 52 The third die 53 to be supported, the fourth die 54 arranged below the first die 51, and the first die 51 are arranged so as to face each other and can be moved in the vertical direction by a punch moving mechanism (not shown). And a bending mold 50 having a punch 55 configured as described above.

  The first die 51 of the bending mold 50 is urged upward by urging means (not shown), and is arranged in a state of being separated from the fourth die 54 as shown in FIG. The upper surface 51b of the first die 51 is formed so that the right side portion thereof is formed by bending the side surface portion W4 of the press-formed plate-like workpiece W1, specifically, the end portion W4e of the second left side surface portion W4b. The shape of the top surface portion W2 and the side surface portion W4 so as to hold the plate-shaped workpiece W1 that is press-formed while the end portion W4e to be bent of the left side surface portion W4b of 2 is positioned above the second die 52. It is formed according to. Further, the left side portion of the upper surface 51b of the first die 51 is formed by bending the side surface portion W3 of the press-formed plate-like workpiece W1, specifically, the end portion W3e of the second right side surface portion W3b. The shape of the top surface portion W2 and the side surface portion W3 so as to hold the press-molded plate-like workpiece W1 in a state where the end portion W3e to be bent of the right side surface portion W3b of the second is positioned above the second die 52. It is formed according to.

  On the other hand, the punch 55 of the bending mold 50 includes a right punch 55a for pressing the press-formed plate-like workpiece W1 held on the right side portion of the upper surface 51b of the first die 51, and the first die 51. And a left punch 55b for pressing the plate-like workpiece W1 held on the left portion of the upper surface 51b.

  In addition, the bending apparatus includes a bending molding apparatus control unit that controls a moving mechanism of the punch 55, and the control unit is provided on the upper and lower sides of the punch 55, specifically, the right punch 55a and the left punch 55b. Control the movement of direction.

  When bending the end portions W3e and W4e of the side surfaces W3 and W4 of the plate-like workpiece W1 using the bending apparatus, the first die 51 is moved upward by the biasing means as shown in FIG. In the state of being urged to the side, the press-formed plate-like workpiece W1 is held on the right side portion of the upper surface 51b of the first die 51 with the first left side surface portion W4a facing downward. Then, the punch 55 of the bending mold 50 is moved downward, and bending is performed by the punch 55 and the second die 52.

  10 and 11 are explanatory diagrams for explaining the bending process, in which FIG. 10 shows a state in which the punch is lowered and the punch and the press-formed plate-shaped workpiece are in contact with each other. The punch is further lowered so that the first die and the fourth die are in contact with each other, and the end portion of the side surface portion of the press-formed plate-like workpiece is bent.

  As shown in FIG. 10, when the punch 55 is lowered while the plate-like workpiece W1 is held on the upper surface 51b of the first die 51, the right punch 55a of the punch 55 comes into contact with the plate-like workpiece W1. . When the punch 55 is further moved downward from this state, the right punch 55a and the second die 52 of the punch 55 are sandwiched between the right workpiece 55a of the punch 55 and the first die 51. As a result, the end W4e of the second right side surface W4b of the side surface W4 is bent inward, and when the first die 51 contacts the fourth die 54 as shown in FIG. The downward movement is stopped and the bending is finished.

  When the bending of the end portion W4e of the side surface portion W4 of the plate-like workpiece W1 is finished, the punch 55 is moved upward, and the plate-like workpiece W1 held by the first die 51 and the first die 51 is moved upward. Is returned to the first position. Then, as shown by a two-dot chain line in FIG. 11, the plate-like workpiece W1 press-formed in a convex shape is rotated by 90 degrees so that the plate-like workpiece W1 is first with the first right side surface portion W3a on the lower side. In the same manner, the end portion W3e of the second left side surface portion W3b of the side surface portion W3 is bent inward by the left punch 55b and the second die 52. The

  In this way, after the end portions W3e and W4e opposite to the top surface portion W2 side of the side surface portions W3 and W4 of the plate-like workpiece W1 are both bent inward, the plate-like workpiece W1 is formed with the top surface portion W2. The convex part W2a provided on the side is press-molded in a direction projecting in the convex shape of the plate-like workpiece W1, which is opposite to the projecting direction, and the side surface parts W3 and W4 on both sides of the top surface part W2 are displaced inward respectively. Be made.

  FIG. 12 is a cross-sectional view showing a press molding die of a second press molding apparatus for press molding the convex portion of the plate workpiece, and FIG. 12 also shows the plate workpiece held by the press molding die. ing. FIGS. 13 to 15 are explanatory views for explaining a press molding process by the second press molding apparatus. FIG. 13 shows a state in which the convex portion of the plate-like workpiece is press-molded. 14 shows a state in which the stripper member has been rotated and moved, and FIG. 15 shows a state in which the punch has been removed from the plate-like workpiece.

  As shown in FIG. 12, the second press molding apparatus for press-molding the convex portion W2a of the plate-like workpiece W1 is disposed above the die 61, the die 61 for holding the plate-like workpiece W1, A press mold (a first mold) having a punch 65 for press-molding the convex portion W2a of the plate-like workpiece W1 held by the die 61 in a direction protruding in the convex shape of the plate-like workpiece W1 opposite to the protruding direction. 2 press molds) 60.

  The die 61 of the press mold 60 is provided with a protrusion 62 for holding the plate-like workpiece W1 at the center thereof. The protrusion 62 has a substantially central portion of the upper surface 62a at the center thereof as shown in FIG. 15 is exaggerated, but a concave portion 63 is formed which is recessed in a curved cross section slightly below the upper surface 62a. The concave portion 63 is formed such that the cross-sectional length L21 in the short side direction on the upper surface 62a is substantially the same as or shorter than the cross-sectional arc length L11 of the convex portion W2a of the plate-like workpiece W1, and is continuous in the longitudinal direction. Is formed. As will be described later, the concave portion 63 corresponds to the crushing portion of the convex portion W2a of the plate-like workpiece W1 on the surface of the die 61 when the convex portion W2a of the plate-like workpiece W1 is press-molded and crushed by the punch 65. It is provided at the site.

  The die 61 of the press mold 60 is also provided with stripper members 64a and 64b formed in an L-shaped cross section on the left and right sides of the protrusion 62. As will be described later, the stripper members 64a and 64b are formed by press-forming the convex portions W2a of the top surface portion W2 of the plate-like workpiece W1 with the punch 65, and the side portions W3 and W4 on both sides of the top surface portion W2 are respectively inward. The end portions W3e and W4e of the side surface portions W3 and W4 are brought into contact with the side surfaces of the punch 65 in a state of being displaced and biased inwardly of the plate-shaped workpiece W1, and then the punch 65 is removed from the plate-shaped workpiece W1. Sometimes it is for holding the plate-like workpiece W1.

  The lower portions of the stripper members 64a and 64b are fixedly attached to rotation shafts 64c and 64d that are rotatably attached to the die 61 by a rotation drive mechanism (not shown). As a result, the stripper members 64a and 64b control the operation of the rotational drive mechanism, so that the stripper members 64a and 64b have the other end portions not attached to the die 61 as shown in FIG. The plate-like workpiece W1 is rotationally moved to the upper side of the end portions W3e, W4e opposite to the top surface portion W2 side of the side surface portions W3, W4.

  As shown in FIG. 12, the punch 65 of the press mold 60 includes an upper surface 65a, a lower surface 65b, a right side surface 65c, and a left side surface 65d, is formed in a rectangular cross section, and is formed continuously in the longitudinal direction. Has been. The lower surface 65b of the punch 65 is formed according to the shape of the lower surface portion 22 of the front side frame 20, and has a cross-sectional length L31 that is substantially the same as the cross-sectional arc shape L11 of the convex portion W2a. It is formed as follows. The punch 65 formed in this way is moved in the vertical direction by a punch moving mechanism (not shown).

  Further, the second press molding apparatus is provided with a second press molding apparatus control unit (not shown) for comprehensively controlling the second press molding apparatus. The apparatus control unit controls various operations such as a moving mechanism of the punch 65 and a rotation driving mechanism of the stripper members 64a and 64b.

  The second press-molding apparatus provided with the press-molding die 60 configured as described above has the plate-like workpiece W1 as the die 61 of the press-molding die 60 and the top surface portion of the plate-like workpiece W1 on the upper surface 62a of the die 61. In a state where W2 is held so as to be disposed, the convex portion W2a of the plate-like workpiece W1 is press-molded in a direction protruding into the convex shape of the plate-like workpiece W1 by the punch 65 and crushed, and the side portions W3, W4 on both sides are pressed. Of the punch 65 in a state where the end portions W3e, W4e of the side surface portions W3, W4 are respectively urged toward the inward side of the plate-like workpiece W1 by the elastic force of the plate-like workpiece W1. Then, the punch 65 is pulled upward from the plate-like workpiece W1 by being brought into contact with 65c, and the end portions W3e, W4e of the side surface portions W3, W4 of the plate-like workpiece W1 are caused by the elastic force of the plate-like workpiece W1. And it is capable of closed cross section of against.

  In the present embodiment, the convex portion W2a of the plate-like workpiece W1 is formed by the side portions W3 and W4 that are displaced inward when the punch 65 moves to the bottom dead center and the convex portion W2a is press-molded and crushed. When the end portions W3e and W4e do not come into contact with the side surfaces 65d and 65c of the punch 65, the end portions W3e and W4e of the side surface portions W3 and W4 are brought into contact with each other so that the plate-like workpiece W1 is closed. The concave portion 63 provided in the die 61 is formed at a portion facing the crushing portion where the punch 65 moves to the bottom dead center and the convex portion W2a is crushed.

  When the convex portion W2a of the plate-like workpiece W1 is press-molded by the punch 65 using the second press-forming apparatus, the top surface portion W2 of the plate-like workpiece W1 is the protruding portion 62 of the die 61 as shown in FIG. The plate-like workpiece W1 is held on the die 61 of the press mold 60.

  When the plate-like workpiece W1 is held by the die 61, the punch 65 is moved downward, and as shown in FIG. 13, the convex portion W2a is pressed downward by the punch 65 in the direction opposite to the protruding direction, and the left top The surface portion W2c and the side surface portion W4 are displaced inward in the direction of closing the plate-like workpiece W1 (counterclockwise in FIG. 13), and the right top surface portion W2b and the side surface portion W3 are directions of closing the plate-like workpiece W1. (In the clockwise direction in FIG. 13), it is displaced inward.

  When the punch 65 moves to the bottom dead center and the convex portion W2a of the plate-like workpiece W1 is press-molded and crushed by the punch 65, as shown in FIG. 13, a crushed portion W2d in which the convex portion W2a is crushed is formed. In addition, the side portions W3 and W4 on both sides of the top surface portion W2 are respectively displaced inward and biased toward the inward side of the plate-like workpiece W1, and the end portions W3e and W4e of the side surface portions W3 and W4. Comes into contact with both side surfaces 65d and 65c of the punch 65, respectively. The end portion W3e of the side surface portion W3 is in contact with the left side surface 65d of the punch in a state where the end portion W3e of the side surface portion W3 is urged inward by the predetermined urging force F1, and the end portion W4e of the side surface portion W4 is Abutting on the right side surface 65c of the punch 65 in a state of being biased inward by a predetermined biasing force F2.

  Then, the side surface portions W3, W4 on both sides are respectively displaced toward the inner side of the plate-like workpiece W1, and the side surface portions W3, W4 are biased toward the inner side of the plate-like workpiece W1, respectively. After the end portions W3e and W4e of W4 are in contact with both side surfaces 65d and 65c of the punch 65, respectively, as shown in FIG. 14, the operation of the rotation drive mechanism is controlled to rotate and move the stripper members 64a and 64b. The other end portion of the stripper members 64a and 64b that is not attached to the die 61 is moved to the upper side of the end portions W3e and W4e opposite to the top surface portion W2 side of the side surface portions W3 and W4 of the plate-like workpiece W1. The

  In this embodiment, the stripper members 64a and 64b are rotationally moved after the convex portion W2a of the plate-like workpiece W1 is crushed by the punch 65, but the punch 65 that crushes the convex portion W2a of the plate-like workpiece W1 is moved. The stripper members 64a and 64b are rotated in conjunction with each other, and the other end of the stripper members 64a and 64b that are not attached to the die 61 is placed on the side opposite to the top surface W2 side of the side surfaces W3 and W4 of the plate-like workpiece W1. You may make it move to the upper part of edge part W3e and W4e.

  While the side surface portions W3 and W4 on both sides are urged toward the inner side of the plate-like workpiece W1, the end portions W3e and W4e of the side surface portions W3 and W4 abut against the both side surfaces 65d and 65c of the punch 65, respectively. After the end portions of the members 64a and 64b move to the upper side of the end portions W3e and W4e of the plate-like workpiece W1, as shown in FIG. 15, the punch 65 is moved upward, and the punch 65 is extracted from the plate-like workpiece W1. .

  When the punch 65 is pulled out from the plate-like workpiece W1 with the side portions W3, W4 on both sides of the top surface portion W2 being urged inwardly of the plate-like workpiece W1, the side portions W3, W4 on both sides are respectively urged force F1. F2 is further displaced inward of the plate-like workpiece W1, the end portions W3e and W4e of the side surface portions W3 and W4 are brought into contact with each other, and the plate-like workpiece W1 is closed. The plate-like workpiece W1 is pressed by the stripper members 64a and 64b when the punch 65 is removed.

  In FIG. 12 to FIG. 15, by pressing the convex portion W2a with the punch 65 while the plate-like workpiece W1 is held on the die 61, the convex portion W2a is crushed and the side portions W3 on both sides of the top surface portion W2. Each of W4 is displaced inward and urged toward the inward side of the plate-like workpiece W1, and is brought into contact with both side surfaces 65d and 65c of the punch 65, and side portions W3 and W4 on both sides of the top surface portion W2. 3 is a cross-sectional view of the front side frame 20 shown in FIG. 3A in order to explain the process of extracting the punch 65 from the plate-like workpiece W1 and making it a closed cross-section while being urged inward of the plate-like workpiece W1. However, other cross sections such as the cross section corresponding to the cross section shown in FIG. 3B are simultaneously press-molded to form a closed cross section.

  As shown in FIG. 15, after the end portions W3e and W4e of the side surfaces W3 and W4 of the plate-like workpiece W1 are brought into contact with each other and the plate-like workpiece W1 is closed, the plate-like workpiece W1 is closed. The end portions W3e and W4e of the side surface portions W3 and W4 are joined together by welding such as laser welding, and the front side frame 20 as a closed cross-section member is manufactured from one plate-like workpiece W1.

  In the present embodiment, the plate-like workpiece W1 is press-molded into a convex shape by draw molding, and the convex portion projects in the direction opposite to the direction in which the plate-like workpiece W1 projects in the convex shape on the top surface portion W2. Although W2a is formed, it may be formed using other press forming such as stretch forming. In the present embodiment, the concave portion 63 provided in the die 61 is formed in a curved cross section, but may be formed in a square cross section such as a rectangular cross section or a trapezoidal cross section.

  As described above, in the method for manufacturing the front side frame 20 as the metal closed cross-section member according to the present embodiment, the plate-like workpiece W1 is press-molded into a convex shape and the top surface portion is molded into the convex shape of the plate-shaped workpiece W1. A first forming step of forming a convex portion W2a projecting in a direction opposite to the convex direction of the plate-like workpiece W1 on W2, and a convex portion W2a by the punch 65 while the plate-like workpiece W1 is held on the die 61 By pressing in the direction opposite to the protruding direction, the convex portion W2a is crushed and the side surface portions W3 and W4 on both sides of the top surface portion W2 are respectively displaced inwardly and attached to the inward side of the plate-like workpiece W1. The second molding step in which the end portions W3e and W4e of the side surface portions W3 and W4 are brought into contact with the both side surfaces W65d and 65c of the punch 65 in a state of being urged, and the end portions W3e and W4e of the side surface portions W3 and W4 on both sides The punch 65 is extracted from the plate-like workpiece W1 in contact with both side surfaces 65d and 65c of the punch 65, and the side portions W3 and W4 on both sides are further displaced inward to make the plate-like workpiece W1 have a closed cross section. The second molding step is performed using the die 61 in which the concave portion 63 is provided in a portion corresponding to the crushing portion W2d of the convex portion W2a of the plate-like workpiece W1 on the surface of the die 61.

  As a result, the deformation amount when the convex portion W2a is crushed can be increased, and the urging forces F1 and F2 that the side surface portions W3 and W4 of the plate-like workpiece W1 urge toward the inner side of the plate-like workpiece W1 can be increased. When the punch 65 is extracted from the plate-like workpiece W1, it is possible to suppress the occurrence of springback, and the side portions W3 and W4e of the plate-like workpiece W1 are well-matched to each other, thereby forming a plate-like shape. The work W1 can be satisfactorily closed. The closed cross-section member 20 can be satisfactorily manufactured from the plate-like workpiece W1 without separately providing a step of pressing the side surfaces W3, W4 of the plate-like workpiece W1 from the outside in order to make the plate-like workpiece W1 have a closed cross section. Can do. Furthermore, in the manufacturing method according to the present embodiment, the closed cross-section member having a flat portion pressed by the punch can be manufactured without limiting the shape of the closed cross-section member in order to achieve a closed cross section.

  Further, during the first forming step and the second forming step, the end portions W3e, W4e opposite to the top surface portion W2 side of the side surface portions W3, W4 of the plate-like workpiece W1 are bent inward of the plate-like workpiece W1. By further comprising a bending process for molding, when displacing the side portions W3 and W4 on both sides inwardly, the displacement of the side portions W3 and W4 to the inward side is reduced and more accurate. A closed cross-section member can be manufactured.

  Further, after the third forming step, a welding step of welding the end portions W3e and W4e of the side surfaces W3 and W4 having a closed cross section of the plate-like workpiece W1 is further provided, thereby joining the closed cross section member 20 The strength can be increased, and a stronger closed section member can be manufactured.

  In the present embodiment, when the plate-like workpiece W1 having a thickness of 1.2 mm is used, the maximum depth of the recess 63 is set to 0.3 mm, that is, formed between the punch 65 and the die 61. By setting the space having the largest space (gap) to be 1.25 times the plate thickness of the plate-like workpiece W1, the plate-like workpiece W1 can be satisfactorily closed. Note that the concave portion 63 provided in the die 61 has the largest space formed between the punch 65 and the die 61 when the convex portion W2a is press-formed by the punch 65. The thickness of the plate-like workpiece W1 is 1. It is preferable to form so as to be 2 to 1.4 times.

  In the embodiment described above, in the press mold 60 of the second press molding apparatus, the concave portion 63 provided at the portion corresponding to the crushing portion W2d of the convex portion W2a of the plate-like workpiece W1 on the surface of the die 61 is provided on the die 61. The protrusion 62 is formed continuously from the upper surface 62a and recessed from the upper surface 62a. The third inclined side surface portion 27 and the fourth inclined side surface portion 28 of the front side frame 20 are formed between the upper surface 62a and the recessed portion 63. You may make it provide the inclination part according to the shape.

  FIG. 16 is a cross-sectional view showing another press forming die of the second press forming apparatus for press forming the convex portion of the plate-like workpiece. In the press mold 70 shown in FIG. 16, an inclined portion is provided between the upper surface 62 a of the die 61 of the press mold 60 and the concave portion 63, and inclined portions corresponding to the inclined portion are provided on both sides of the lower surface of the punch 65. Since it is the same as the press mold 60 except that it is provided, the same reference numerals are assigned to the same components, and the description thereof is omitted. Note that FIG. 16 shows a state in which the plate-like workpiece W1 is held by the press mold 70.

  As shown in FIG. 16, the die 71 of the press mold 70 is provided with a right inclined portion 72b inclined obliquely downward to the left from the upper surface 72a and a left inclined portion 72c inclined obliquely downward and right from the upper surface 72a. Further, a concave portion 73 is provided in a portion corresponding to the crushing portion of the convex portion W2a of the plate-like workpiece W1 on the surface of the die 71. The concave portion 73 is exaggerated in FIG. The lower end portion of the front side frame 20 is connected to the lower end portion 72c of the front side frame 20 so as to be slightly depressed below the molding line L2 corresponding to the shape of the lower surface portion 22 and formed in a curved cross section. The concave portion 73 is formed such that the cross-sectional length L41 in the short direction in the forming line L2 is substantially the same as the cross-sectional arc length L11 of the convex portion W2a of the plate-like workpiece W1, and is continuous in the longitudinal direction. Is formed.

  In the present embodiment, the inclined portions 72b and 72c of the die 71 are each formed to have a cross-sectional length substantially the same as the shortest cross-sectional length of the top surface portion W2 that changes in the longitudinal direction, and the right inclined portion. 72b is formed to have substantially the same cross-sectional length as the shortest cross-sectional length of the left top surface portion W2c, and the left inclined portion 72c has the shortest cross-sectional length of the right top surface portion W2b. They are formed so as to have substantially the same cross-sectional length. In addition, the inclination angles of the inclined portions 72b and 72c with respect to the molding line L2 are substantially constant in the longitudinal direction according to the shapes of the third inclined side surface portion 27 and the fourth inclined side surface portion 28 of the front side frame 20, respectively. It is formed at an angle.

  As shown in FIG. 16, the punch 75 of the press mold 70 has an upper surface 75a, a lower surface 75b, a right side surface 75c, a left side surface 75d, and a right inclined surface inclined obliquely upward to the right from the lower surface 75b toward the right side surface 75c. A side surface 75e and a left inclined side surface 75f inclined obliquely left upward from the lower surface 75b toward the left side surface 75d are formed continuously in the longitudinal direction with the same cross-sectional shape. The lower surface 75b, the right inclined side surface 75e, and the left inclined side surface 75f of the punch 75 are formed according to the shapes of the lower surface portion 22, the third inclined side surface portion 27, and the fourth inclined side surface portion 28 of the front side frame 20, respectively. The lower surface 75b of the punch 75 is formed such that the cross-sectional length L51 in the short direction thereof has substantially the same cross-sectional length as the cross-sectional arc length L11 of the convex portion W2a.

  The plate-like workpiece W1 is held by the die 71 even when the convex portion W2a of the plate-like workpiece W1 is press-molded using the second press-molding apparatus having the press-molding die 70 configured as described above. Then, the punch 75 is moved downward, and the convex portion W2a is pressed downward by the punch 75, which is opposite to the protruding direction. As a result, the left top surface portion W2c and the side surface portion W4 are displaced inward in the direction of closing the plate-like workpiece W1 with the intersection of the right inclined portion 72b and the upper surface 72a as a fulcrum, and the right top surface portion W2b and the side surface portion W3 are The plate-like workpiece W1 is displaced inward in the closing direction with the intersection of the left inclined portion 72c and the upper surface 72a as a fulcrum.

  When the punch 75 moves to the bottom dead center, the convex portion W2a of the plate-like workpiece W1 is press-molded and crushed by the punch 75 to form a crushed portion in which the convex portion W2a is crushed, and side surfaces on both sides of the top surface portion W2. The end portions W3e and W4e of the side surface portions W3 and W4 are moved to both side surfaces 75d and 75c of the punch 75 in a state where the portions W3 and W4 are respectively displaced inwardly and urged toward the inward side of the plate-like workpiece W1. Each abuts. And the operation | movement of the said rotation drive mechanism is controlled, and the other edge part which is not attached to the die | dye 61 of stripper member 64a, 64b is the opposite side to the top surface part W2 side of side part W3, W4 of plate-shaped workpiece W1. Are moved to the upper side of the end portions W3e and W4e.

  Thereafter, when the punch 65 is extracted from the plate-like workpiece W1 with the side portions W3, W4 on both sides of the top surface portion W2 being urged toward the inside of the plate-like workpiece W1, the side portions W3, W4 on both sides are respectively Further, the plate-like workpiece W1 is displaced inward, the end portions W3e and W4e of the side surface portions W3 and W4 are brought into contact with each other, and the plate-like workpiece W1 is closed.

  As described above, also in the second press molding apparatus provided with the press mold 70, the die 71 having the concave portion 73 provided in the portion corresponding to the crushing portion of the convex portion W2a of the plate-like workpiece W1 on the surface of the die 71 is provided. By using the second molding step, it is possible to suppress the occurrence of springback when the punch 75 is extracted from the plate-like workpiece W1, and the end portions of the side portions W3 and W4 of the plate-like workpiece W1. W3e and W4e can be satisfactorily matched, and the plate-like workpiece W1 can be satisfactorily closed.

  Further, in the second press molding apparatus provided with the press molding die 70, when the cross-sectional length of the portions W2c and W2b into which the top surface portion W2 is divided by the convex portion W2a is molded to change in the longitudinal direction. In addition, the cross-sectional lengths of the inclined portions 72b and 72c are set to be substantially the same as the shortest cross-sectional lengths of the divided portions W2c and W2b of the top surface portion W2, respectively. The top surface portions W2c and W2b corresponding to the inclined side surface portion 27 and the fourth inclined side surface portion 28 can be raised at substantially the same timing in the longitudinal direction, and the press molding can be performed stably.

  As described above, the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the gist of the present invention.

  The present invention relates to the manufacture of a metal closed cross-section member that manufactures a closed cross-section member from a metal plate-like workpiece. For example, a vehicle body member formed in a closed cross-section shape such as a front side frame, a rear side frame, or a dash cross member. It can be effectively applied in manufacturing.

20 Front side frame 40 First press mold 60, 70 Second press mold 61, 71 Second press mold die 63, 73 Recesses 65, 75 provided on the second press mold die Second press mold punch 65c, 65d, 75c, 75d Side surface of second press mold punch W1 Plate workpiece W2 Top surface portion of plate workpiece W2a Convex portion W3 provided on top surface portion of plate workpiece W3, W4 Side face part of plate-like work W3e, W4e End part on the opposite side to the top face side of the side face part of the plate-like work

Claims (4)

  A metal plate-like workpiece is press-molded into a convex shape, and a convex portion projecting in a direction opposite to the convex shape of the plate-like workpiece is formed on the top surface portion of the plate-like workpiece. In the first molding step, the convex part is crushed in a direction opposite to its projecting direction by punching with the plate-shaped workpiece held on the die, and the convex part is crushed and side surfaces on both sides of the top surface part A second forming step in which the end portions of the side surface portions are brought into contact with both side surfaces of the punch in a state where the respective portions are displaced inwardly and are urged toward the inward side of the plate-like workpiece; The punch is removed from the plate-like workpiece in a state where the end portions of the portions are in contact with both side surfaces of the punch, and the side portions on both sides are further displaced inward to form a closed cross-section of the plate-like workpiece. A metal closed cross-section member comprising: The metal is characterized in that the second forming step is performed using a die in which a concave portion is provided in a portion corresponding to the crushing portion of the convex portion of the plate-like workpiece on the surface of the die. A method for producing a closed cross-section member.   2. The method for manufacturing a metal closed cross-section member according to claim 1, wherein the concave portion provided in the die is formed in a cross-sectional curve shape or a cross-sectional angular shape.   A bending step of bending the end portion of the side surface portion of the plate-like workpiece opposite to the top surface portion side to the inward side of the plate-like workpiece is further performed between the first molding step and the second molding step. The method for producing a metal closed cross-section member according to claim 1, wherein the metal closed-section member is provided.   4. The method according to claim 1, further comprising, after the third forming step, a welding step of welding the end portions of the side surface portion of the plate-like workpiece having a closed cross section. The manufacturing method of the metal closed cross-section member of description.

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