JP2016203254A - Manufacturing method of press formed article and press device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a specific press formed article preventing occurrence of bending of a curvature wall in a plate thickness direction, the specific press formed article being a press formed article comprising: the curvature wall curving in a convex shape in the plate thickness direction; and a flange one end of which is connected with a curved end of the curvature wall, and arranged in a side opposite to a curving side of the curvature wall in the convex shape in the plate thickness direction.SOLUTION: A manufacturing method of a press formed article which is a method for manufacturing a specific press formed article by use of a die, a punch, and a holder comprises: a first step in which a portion of a blank to be formed as a flange is bent at a tilt angle that is 60° or less; and a second step in which the blank is pressed by the die and the punch while the portion is sandwiched between the die and the holder after the first step so as to form a curvature wall and the flange in the blank.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a press-formed product and a press apparatus.

  The body of an automobile is assembled by superimposing edges of a large number of molded panels and joining them by spot welding to form a box, and joining structural members to the essential parts of the box by spot welding. For example, on the side part (body side) of an automobile body, as a structural member, a side sill joined to both side parts of a floor panel, an A pillar lower and an A pillar upper erected upward on the front part of the side sill, A roof rail joined to the upper end portion of the A pillar upper, and a B pillar that joins the side sill and the roof rail are used.

  Components of structural members such as an A pillar lower, an A pillar upper, and a roof rail (for example, each outer panel) generally have a top plate that extends in the longitudinal direction, and two components that are respectively connected to both sides of the top plate. Consists of a convex ridge line part, two vertical walls respectively connected to these two convex ridge line parts, two concave ridge line parts respectively connected to these two vertical wall parts, and two flanges respectively connected to these two concave ridge line parts Often has a substantially hat-shaped longitudinal cross-sectional shape.

  The above-described components have a relatively complicated longitudinal section shape and are long. Therefore, in order to suppress an increase in manufacturing cost, the above-described components are generally manufactured by cold press molding. Further, in order to achieve both weight reduction and strength improvement of the vehicle body for improving fuel efficiency, thinning using, for example, a high-tensile steel plate having a tensile strength of 440 MPa or more is promoted as the above-described structural member.

  However, a high-tensile steel plate is bent in the longitudinal direction by cold press forming, for example, a roof rail outer panel (hereinafter referred to as a roof member. The roof member is a structural member of an automobile). When it is going to manufacture a component, a springback may generate | occur | produce at the time of mold release from a press type | mold, and there exists a possibility that a top plate may twist. As a result, there arises a problem of shape freezing property that the roof member cannot be formed into a desired shape.

  For example, Patent Document 1 discloses an invention in which, when a press-formed product having a hat-shaped vertical cross section that is uniform in the longitudinal direction is manufactured, the generation of a mouth opening is suppressed by providing a step, thereby increasing the shape freezing property. It is disclosed.

  Further, in Patent Document 2, when manufacturing a press-formed product having a top plate, a vertical wall, and a flange and curved in the longitudinal direction, the flange formed in the first step is bent back in the second step to An invention is disclosed in which the shape freezing property is improved by reducing the residual stress.

JP 2004-314123 A Japanese Patent No. 5382281

  According to the invention disclosed in Patent Document 1, for example, when a press-molded product having a shape curved in the longitudinal direction, such as a component of a component of an A pillar lower, an A pillar upper, and a roof rail, is manufactured, a spring after release The curved wall is bent by the back and cannot be formed into a desired shape.

  According to the invention disclosed in Patent Document 2, when a press-molded product that is bent in the longitudinal direction and the height direction and has a bent portion in the vicinity of the center in the longitudinal direction is produced, the residual stress of the flange, the longitudinal wall, and the top plate Residual stress and deviation residual stress in the plane of the vertical wall and the top plate are generated. As a result, the press-molded product is bent from the top plate side due to the spring back after releasing (bending in the thickness direction of the vertical wall), and cannot be formed into a desired shape.

  One of the causes of the released spring pack in Patent Document 1 and Patent Document 2 is the tensile stress generated by the inflow resistance (deformation resistance) generated in the blank that flows toward the die hole.

  An object of this invention is to provide the method of manufacturing the specific press-molded product by which generation | occurrence | production of the bending to the plate | board thickness direction of a curved wall was suppressed. Here, the specific press-molded product is a curved wall that is curved in a convex shape with respect to the plate thickness direction, and one end connected to the curved end of the curved wall, and the curved wall in the plate thickness direction is This refers to a press-molded product that includes a convexly curved side and a flange disposed on the opposite side (hereinafter the same applies in this specification). In addition, in another viewpoint, the specific press-formed product is a press-formed product in which a ridge line between the curved wall and the flange is convexly curved toward the curved wall (outside of the flange).

  A method for producing a press-formed product according to the present invention includes a curved wall that is curved in a convex shape with respect to the plate thickness direction using a die, a punch, and a holder, and an end at which one end of the curved wall is curved. And a flange formed on the opposite side to the curved wall of the curved wall in the thickness direction, and a method of manufacturing a press-molded product comprising a flange, A first step of bending a portion where a flange is formed at an inclination angle of 60 ° or less; and after the first step, with the die and the punch being sandwiched between the die and the holder, A second step of pressing the blank to form the curved wall and the flange on the blank.

  The press device according to the present invention is adjacent to a die hole, a die shoulder that forms a ridge line that curves convex toward the die hole, and the die shoulder on the opposite side of the die hole across the die shoulder. A die having a first surface and a plate pressing surface having a convex or concave second surface having a tilt angle of 60 ° or less with respect to the first surface which is on the normal line of the ridgeline, and the die And a holder having a plate pressing surface having a shape corresponding to the plate pressing surface. The corresponding shape means a shape in which the convex and concave are inverted. The holder moves relative to the die, and can be bent with a blank sandwiched between the plate pressing surfaces. The first surface may be curved, in which case the convex or concave second surface with respect to the first surface means that the irregularities are larger than the first surface. From another viewpoint, it means that the surface length of the surface on the cross section including the second surface is longer than the surface length of the surface on the cross section of only the first surface on the cross section parallel to the ridge line.

  If the method for producing a press-formed product according to the present invention is used, a specific press-formed product in which the bending of the curved wall in the plate thickness direction is suppressed can be produced.

  If the press apparatus which concerns on this invention is used, the specific press molded product by which generation | occurrence | production of the bending to the plate | board thickness direction of a curved wall was suppressed can be manufactured.

It is a top view of the roof member (press molded product) of 1st Embodiment, and a front view of the one end part of a roof member. It is the perspective view which represented a part of roof member of 1st Embodiment with the longitudinal cross-sectional view. It is a figure of the metal mold | die of the press apparatus used in the manufacturing method of the roof member of 1st Embodiment, Comprising: It is the perspective view which made a part of upper mold the cross section. It is a longitudinal cross-sectional view which shows the state which the press apparatus used in the manufacturing method of the roof member of 1st Embodiment press-molds a blank and manufactures the roof member. It is a figure which shows the state in which the metal mold | die of the press apparatus used in the manufacturing method of the roof member of 1st Embodiment has pinched the blank, Comprising: It is a side view equivalent to the figure seen from the direction of the arrow 5 of FIG. . It is a longitudinal cross-sectional view which shows the state which the press apparatus used in the manufacturing method of the roof member of a comparison form press-molds a blank, and manufactures the roof member. It is a figure for demonstrating the evaluation method of the curvature of a roof member, Comprising: It is a figure corresponded in the front view of the one end part of the roof member of FIG. When the press device used in the method for manufacturing the roof member of the comparative form presses the blank to manufacture the roof member, the force acting on the blank flowing into the groove (die hole) from the convexly curved die shoulder FIG. 6 is a plan view of the blank of FIG. 5 as viewed from above. FIG. 5 is a view for explaining the force acting on the bent portion of the blank in the state where the mold of the press apparatus used in the method for manufacturing the roof member of the first embodiment sandwiches the blank. It is a corresponding side view. It is a top view which shows the roof member of 2nd Embodiment. It is a table | surface which shows the evaluation result by the simulation about the bending of the roof member of the Example (Examples 1-5) of 1st Embodiment, and the bending of the roof member of a comparative example (Comparative Examples 1-4). It is a table | surface which shows the evaluation result by the simulation about the bending of the roof member of the Example (Example 6) of 2nd Embodiment, and the bending of the roof member of a comparative example (comparative example 5). It is a perspective view of the metal mold | die of the press apparatus used in the manufacturing method of the roof member of a modification. It is a longitudinal cross-sectional view which shows the state which the press apparatus used in the manufacturing method of the roof member of a modification manufactures the roof member by press-molding a blank.

≪Overview≫
Hereinafter, modes (first embodiment and second embodiment) for carrying out the present invention will be described. Next, examples will be described.

<< First Embodiment >>
The first embodiment will be described below. First, the structure of the roof member 1 (refer FIG.1 and FIG.2) of this embodiment is demonstrated. Next, the configuration of the press device 18 (see FIGS. 3 and 4) of the present embodiment will be described. Next, a method for manufacturing the roof member 1 of the present embodiment will be described. Next, the operation of this embodiment will be described. In addition, the roof member 1 of this embodiment is corresponded in Example 1 in the Example mentioned later (refer the table | surface of FIG. 8).

<Configuration of roof member>
First, the structure of the roof member 1 of this embodiment is demonstrated, referring drawings. Here, the roof member 1 is an example of a press-formed product and a specific press-formed product.

  As shown in FIG. 1 and FIG. 2, the roof member 1 includes a top plate 2, two vertical walls 4 a and 4 b, and two flanges 6 a and 6 b that are integrally formed. The surface shape is a substantially hat-shaped long member. As an example, the roof member 1 is a cold press-formed product made of a high-tensile steel sheet having a tensile strength of 1310 MPa.

  The top plate 2 is long as shown in FIGS. 1 and 2. Further, when viewed from the upper side (of the top plate 2), the top plate 2 is curved along the longitudinal direction (arrow L1 in the drawing) as shown in FIG.

  The two vertical walls 4a and 4b are opposed to each other in a state of extending from both ends of the top plate 2 in the short direction. Further, as shown in FIG. 1, the two vertical walls 4 a and 4 b are curved along the longitudinal direction of the top plate 2 when viewed from above the top plate 2. That is, the two vertical walls 4 a and 4 b of the present embodiment face each other in a state of extending from both ends of the top plate 2 in the short direction, and are curved as viewed from the top of the top plate 2. The vertical wall 4a is convexly curved toward the vertical wall 4b (the side facing the vertical wall 4b), and the vertical wall 4b faces the side opposite to the vertical wall 4a (the side facing the vertical wall 4a). It is curved in a concave shape. From another viewpoint, it can be said that the vertical wall 4a is a curved wall that is curved in a convex shape with respect to one of the plate thickness directions (arrow A direction in the figure). Here, the vertical wall 4a is an example of a curved wall.

  As shown in FIGS. 1 and 2, the flange 6a has one end connected to the end of the vertical wall 4a opposite to the side connected to the top plate 2. The flange 6a is connected to the entire region in the longitudinal direction at the end opposite to the side connected to the top plate 2 in the vertical wall 4a. The flange 6a extends to the opposite side of the top plate 2 in the thickness direction of the vertical wall 4a. The end of the flange 6a on the side connected to the vertical wall 4a is curved convexly on the top plate 2 side (vertical wall 4a side) when viewed from the top of the top plate 2, and connected to the vertical wall 4a of the flange 6a. The end opposite to the opposite side is curved in a concave shape on the opposite side (vertical wall 4a side) of the top plate 2 as viewed from above the top plate 2. In addition, the smaller angle among the angles with respect to the vertical wall 4a formed with respect to each part in the longitudinal direction of the flange 6a is an obtuse angle.

  As shown in FIGS. 1 and 2, the flange 6 b has one end connected to the end of the vertical wall 4 b opposite to the side connected to the top plate 2. Further, the flange 6b extends to the opposite side of the top plate 2 in the thickness direction of the vertical wall 4b. The end of the flange 6b opposite to the side connected to the vertical wall 4b is curved in a convex shape on the opposite side of the top plate 2 when viewed from above the top plate 2. In addition, the flange 6a is connected to the whole area of the longitudinal direction in the end on the opposite side to the side connected to the top plate 2 in the vertical wall 4b. In addition, the smaller angle among the angles with respect to the vertical wall 4b formed with respect to each part in the longitudinal direction of the flange 6b is an obtuse angle.

  As shown in FIGS. 1 and 2, the roof member 1 includes a first portion 8 including one end 1a, a third portion 10 including the other end 1b, and a first portion. 8 and the second portion 9 connecting the third portion 10 can be said to be integrated.

  Here, in the present embodiment, as viewed from above (as viewed from above the top plate 2), the radius of curvature of the first portion 8 is, for example, larger than 2000 (mm) and not larger than 9000 (mm). The radius of curvature of the portion 9 is, for example, 500 (mm) or more and 2000 (mm) or less, and the radius of curvature of the third portion 10 is, for example, greater than 2000 (mm) and 9000 (mm) or less. In addition, the radius of curvature of the vertical wall 4a of the first portion 8 is, for example, greater than 2000 (mm) and 9000 (mm) or less, and the radius of curvature of the vertical wall 4a of the second portion 9 is, for example, 500 (mm). The radius of curvature of the vertical wall 4a of the third portion 10 is, for example, greater than 2000 (mm) and not greater than 9000 (mm). That is, the curvature radius of the vertical wall 4a of the second portion 9 is smaller than the curvature radius of the vertical wall 4a of the portions 8 and 10 on both sides in the longitudinal direction.

  In addition, as shown in FIG.1 and FIG.2, the roof member 1 of this embodiment is made into the state which the both ends in the longitudinal direction opened.

  The above is description about the structure of the roof member 1 of this embodiment.

<Configuration of press machine>
Next, the press apparatus 18 of this embodiment is demonstrated, referring drawings. The press device 18 of the present embodiment is for manufacturing the roof member 1 of the present embodiment by press-forming a blank 30 (see FIG. 4) by drawing. As shown in FIGS. 3 and 4, the pressing device 18 includes a mold 20 and a moving device 25. Here, the blank 30 is a long high-tensile steel plate (in the case of this embodiment, a high-tensile steel plate having a tensile strength of 1310 MPa as an example) that is a base material for manufacturing the roof member 1. In the present specification, “press molding” means that a product to be molded (in the case of this embodiment, the blank 30 as an example) is set in the mold 20 and then the mold is closed to open the mold. It means the act until it is done. That is, “press forming” means pressing (pressurizing) an object to be formed and forming.

  As shown in FIGS. 3 and 4, the mold 20 includes an upper mold 21, a lower mold 22, a first holder 23, and a second holder 24. The upper mold 21 is disposed on the upper side, and the lower mold 22 is disposed on the lower side. Here, the upper die 21 is an example of a die, and the lower die 22 is an example of a punch.

  The upper mold 21 and the lower mold 22 are each elongated as shown in FIG. When viewed from the facing direction of the upper mold 21 and the lower mold 22 (hereinafter, sometimes referred to as the vertical direction in the present specification), the lower mold 22 protrudes while being curved along the longitudinal direction. A long groove 21 a (die hole) that is curved along the mold 22 is formed. That is, the upper mold 21 is formed with a groove 21a that is curved along the longitudinal direction. Here, the groove 21a is an example of a die hole. When the lower die 22 is relatively moved toward the upper die 21 by the moving device 25, the lower die 22 is fitted in the groove 21a. That is, the shape of the lower mold 22 is a shape that fits into the groove 21a.

  Both sides in the short direction of the groove 21a are mold closing surfaces 21b. As shown in FIGS. 3 and 4, the mold closing surface 21 b of the present embodiment is a plane perpendicular to the vertical direction. That is, the groove 21a is adjacent to the mold closing surface 21b on both sides in the short direction. Here, the mold closing surface 21b is an example of a first surface. As shown in FIG. 3, the groove 21a is formed by a surface including a long bottom surface 21a1, a curved surface 21a2 connected to one end in the short direction of the bottom surface 21a1, and a curved surface 21a3 connected to the other end. . The edge 21a31 (die shoulder) on the curved surface 21a3 is a ridge line that curves in a convex shape toward the groove 21a. In this specification, the part including the edge in the curved surface 21a3 is referred to as a die shoulder. Further, as shown in FIG. 4, when the upper mold 21 is viewed from above and below, the curved surface 21a2 is concavely curved in the short direction (the direction in which the curved surface 21a2 and the curved surface 21a3 face each other), and the curved surface 21a3. Is curved convexly in the short direction.

  When viewed from the longitudinal direction of the upper mold 21, the upper mold 21 has a continuous width of the groove 21 a from the bottom (bottom surface 21 a 1) of the groove 21 a toward the opening side of the groove 21 a (from the upper side to the lower side). It is getting wider. When the lower mold 22 is viewed from the longitudinal direction of the lower mold 22, the width of the protruding portion is continuously narrowed from the lower side toward the upper side.

  Further, as shown in FIGS. 3 and 5, the longitudinal plate holding surface of the upper die 21 is opposite to the groove 21a across the die closing surface 21b and is a curved surface 21a31 in the groove 21a. A concave surface 21c is formed on the side (die shoulder side). As shown in FIG. 5, the recessed surface 21 c is a surface recessed in a curved shape in the longitudinal direction when viewed from the short direction of the upper mold 21. That is, the concave surface 21c is a concave surface with respect to the mold closing surface 21b. Here, the recessed surface 21c is an example of a second surface. Moreover, the inclination angle θ (see FIG. 4) with respect to the vertical direction of the cross section at the center position in the longitudinal direction of the concave surface 21c is 45 (°) as an example. The distance D1 (see FIG. 4) between the edge on the groove 21a side in the longitudinal direction of the concave surface 21c and the edge 21a31 of the groove 21a in the short direction of the upper die 21 is 24.00 (as an example). mm). Hereinafter, the separation distance D1 is referred to as a holder offset amount. Note that the curved surface 21a3 side (die shoulder side) in the groove 21a is the outside of the groove 21a in the direction of the normal line of the edge 21a31 in the curved surface 21a3 (short direction in the present embodiment). The concave surface 21 is formed on the short side (normal direction) side of the portion having the smallest curvature radius in the longitudinal direction of the groove 21a. From another viewpoint, the concave surface 21c is formed on the short side (normal direction) side of the portion of the edge 21a31 of the groove 21a having the smallest radius of curvature.

  Here, the concave surface 21c will be described in detail. The concave surface 21c has the following shape. That is, the concave surface 21c is a concave from the upper surface (the mold closing surface 23a described later) of the first holder 23 as the upper die 21 is viewed from the short side and away from the longitudinal center to both ends in the longitudinal direction. The amount is formed so as to gradually decrease (see FIGS. 3 and 5). From another viewpoint, when the upper mold 21 is viewed in the longitudinal direction, the recessed surface 21c closes as it approaches the groove 21a side (edge 21a31 side) from the end in the short direction, as shown in FIG. The dent amount from the surface 23a is formed so as to be gradually reduced.

  Generally, in order to prevent wrinkles and plate thickness fluctuations due to excessive inflow of blanks in drawing, it is possible to create inflow resistance of blanks that flow into the die holes by providing irregularities (beads) on the plate pressing surfaces of the die and holder. is there. On the other hand, this embodiment is for suppressing the deterioration of the dimensional accuracy of the roof member 1 (an example of a press-formed product) due to deformation resistance and inflow resistance generated when the blank flows in. Accordingly, the concave surface 21c and the bead are different in shape. The boundary between the mold closing surface 21b and the recessed surface 21c is gentle. Since the bead generates high inflow resistance, the boundary between the bead and the mold closing surface is bent sharply. Specifically, first, the angle formed by the bead and the mold closing surface is close to 90 °, whereas the mold closing surface 21b in the inflow direction (normal direction of the ridge line) of the blank 30 shown in FIG. The angle formed by the concave surface 21c (which means the tilt angle θ of the boundary) is preferably 60 ° or less. If the inclination angle θ is small, it is difficult to achieve the above-described effect (suppressing deterioration of the dimensional accuracy of the roof member 1). Therefore, the inclination angle θ on the normal line of the smallest curvature radius of the ridge line is 30 ° or more. It is desirable that Second, the radius of curvature of the boundary between the bead and the mold closing surface is small, but the radius of curvature of the boundary between the mold closing surface 21b and the recessed surface 21c in the inflow direction (normal direction of the ridgeline) of the blank 30 is 10 mm or more. It is desirable that it is (more than 5 times the thickness of the blank 30). Further, unlike the embodiment shown in FIG. 4, if there is a vertex in the recessed surface 21c, the inflow resistance is generated by the deformation resistance that is stretched in the longitudinal direction until the inflowing blank 30 passes through the vertex. Therefore, as described above, when the upper mold 21 is viewed in the longitudinal direction, the concave surface 21c is a mold closing surface as it approaches the groove 21a side (edge 21a31 side) from the end in the short direction as shown in FIG. It is desirable that the dent amount from 23a be gradually reduced. The convex surface 23b provided on the plate pressing surface of the holder, which will be described later, is the same because it has a shape paired with the concave surface 21c.

  As shown in FIG. 3, the first holder 23 and the second holder 24 are long and are respectively disposed on both sides of the lower mold 22 in the short direction. The first holder 23 and the second holder 24 are urged upward by springs 26 and 27, respectively.

  As shown in FIGS. 3 and 4, the second holder 23 is disposed on the lower mold of the upper mold 21 where the recessed surface 21 c and the mold closing surface 21 b are formed. On the upper surface of the second holder 23, there are formed a mold closing surface 23a perpendicular to the vertical direction and a curved convex surface 23b fitted to fit the concave surface 21c.

  The moving device 25 is configured to move the upper mold 21 toward the lower mold 22. That is, the moving device 25 moves the upper mold 21 relative to the lower mold 22.

  Then, when the moving device 25 moves the upper mold 21 toward the lower mold 22 in a state where the blank 30 is disposed in the gap between the upper mold 21 and the lower mold 22, as shown in FIG. The roof member 1 is manufactured by press-molding the blank 30 in a state where both end sides in the short direction are sandwiched between the first holder 23 and the second holder 24 and the upper mold 21 respectively. As described above, since the concave surface 21 c is formed on the upper mold 21 and the convex surface 23 b is formed on the first holder 23, the press device 18 of the present embodiment deforms the blank 30 to deform the top plate 2. Before the vertical walls 4a and 4b and the flanges 6a and 6b are formed, the portion of the blank 30 sandwiched between the first holder 23 and the upper mold 21 is bent into the shape of the concave surface 21c (or the convex surface 23b). The roof member 1 is manufactured.

  As described above, the press device 18 has been described, but when the press device 18 is viewed from another perspective, the press device 18 is as follows. That is, the press device 18 of the present embodiment includes at least the upper die 21, the lower die 22, and the first holder 23 as described above. The upper mold 21 has a groove 21a, a die shoulder that forms a ridge line curved toward the groove 21a (the edge 21a31 of the curved surface 21a3), and a direction normal to the edge 21a31. It has a concave surface 21c which is formed on the shoulder side of the die and is concave with respect to the mold closing surface 21b adjacent to the groove 21a. Further, the lower mold 22 is disposed so as to face the upper mold 21 and is relatively moved toward the upper mold 21 so as to be fitted into the groove 21a. Further, the first holder 23 is formed with a convex surface 23 b that faces the concave surface 21 c of the upper mold 21. And the 1st holder 23 moves relatively toward the upper mold | type 21, bends the blank 30 with the convex surface 23b and the concave surface 21c of the upper mold | type 21, and makes the convex surface 23b and the concave surface 21c of the upper mold | type 21 with The blank 30 is sandwiched between them.

  The above is the description of the configuration of the press device 18 of the present embodiment.

<Manufacturing method of roof member>
Next, the manufacturing method of the roof member 1 of this embodiment is demonstrated, referring drawings. The manufacturing method of the roof member 1 of the present embodiment is performed using the press device 18. Moreover, the manufacturing method of the roof member 1 of this embodiment includes the 1st process mentioned later and the 2nd process.

[First step]
In the first step, the blank 30 is disposed in the gap between the upper mold 21 and the lower mold 22, and the flange 30 in the blank 30 is sandwiched between the first holder 23 and the second holder 24 and the upper mold 21. This is a step of bending the portion where 6a is formed. Here, the gentle means that the blank 30 is bent when the inclination angle of the boundary of the portion where the flange 6a is formed is 60 ° or less. Specifically, when the operator operates the press device 18, the upper die 21 is moved to the lower die 22 side by the moving device 25, and the portion where the flange 6 a is formed in the blank 30 is the first holder 23 and the upper die. 21, the portion of the blank 30 where the flange 6 b is formed is sandwiched between the second holder 24 and the upper mold 21. In this case, the portion of the blank 30 where the flange 6a is formed is bent (plastically deformed) by the first holder 23 and the upper mold 21 into a shape along the concave surface 21c (or the convex surface 23b). At the end of the first step, the portion of the blank 30 where the top plate 2 and the vertical walls 4a and 4b are formed is still flat (not shown). That is, at the end of the first step, the upper surface of the lower mold 22 is positioned below the mold closing surface 21b of the upper mold 21 in the vertical direction.

[Second step]
The second step is a step after the first step, and the upper die 21 and the first holder 23 are sandwiched between the upper die 21 and the first holder 23 and the portion of the blank 30 where the flange 6a is formed. The blank 30 is pressed and the top plate 2, the vertical walls 4a and 4b, and the flanges 6a and 6b are formed on the blank 30. Specifically, the upper die 21 is moved toward the lower die 22 by the moving device 25, so that the lower die 22 fits into the groove 21a of the upper die 21, and the top plate 2, the vertical walls 4a, 4b from the blank 30. And the flanges 6a and 6b are press-molded. And the roof member 1 is manufactured when a 2nd process is complete | finished.

  The above is the description of the method for manufacturing the roof member 1 of the present embodiment.

<Action>
Next, the operation of the present embodiment will be described by comparing the present embodiment with a comparative embodiment to be described later. In the description of the comparative embodiment, when the same parts as the parts used in the present embodiment are used, the reference numerals of the parts are used as they are even when not shown. In addition, the roof member (illustration omitted) of a comparison form is corresponded to the comparative example 1 in the comparative example mentioned later (refer the table | surface of FIG. 11).

  In the case of the comparative form, in the manufacturing process, the roof member is manufactured without bending the portion of the blank 30 where the flange 6a is formed. That is, in the case of the comparative embodiment, as shown in FIG. 6, the mold closing surface 21 b of the upper mold 21 of the pressing device 18 </ b> A is not formed with the recessed surface 21 c, and the mold closing surface 23 a of the first holder 23 is not formed. The convex surface 23b is not formed. Except for these points, the roof member of the comparative form is manufactured by using the press device 18A having the same configuration as the press device 18 of the present embodiment (see FIG. 4).

  Here, in the evaluation of the bending of the front end and the bending of the rear end, the roof member 1 created by the simulation based on the manufacturing of the roof member of the present embodiment and the data of the roof member created by the simulation based on the manufacturing of the roof member of the comparative form. Data (hereinafter referred to as measurement data) and design data were compared. Specifically, the cross section of the center portion in the longitudinal direction of the top plate 2 is matched (best fit), and the center position of one end 1a (the other end 1b) of the measured data with respect to the center position of the design data in the width direction. The amount of deviation was defined as the leading end bending (rear end bending), and the average value of the leading end bending value and the rear end bending value was defined as the average bending amount (see FIG. 7).

  Then, according to the evaluation result of the comparative form (Comparative Example 1), as shown in the table of FIG. 11, the tip end curve is 11.12 (mm), the rear end curve is 5.07 (mm), and the average curve. The amount was 8.095 (mm).

  On the other hand, according to the evaluation result of the present embodiment (Example 1), as shown in the table of FIG. 11, the front end portion of the roof member 1 created by the simulation based on the manufacture of the roof member 1 of the present embodiment. The bending was 5.56 (mm), the rear end bending was 2.54 (mm), and the average bending amount was 4.05 (mm). That is, the values of all the evaluation items in the evaluation result of the present embodiment are smaller than the values of all the evaluation items in the evaluation result of the comparative form. In other words, it can be said that the roof member 1 of the present embodiment is less likely to bend in the thickness direction of the vertical wall 6a than the roof member of the comparative embodiment. In the present specification, “the occurrence of bending in the thickness direction of the vertical wall 6a is suppressed” means “the amount of bending in the thickness direction of the vertical wall 6a is relatively small”. .

  As described above, in the case of the present embodiment, the reason why the occurrence of the bending of the vertical wall 6a in the plate thickness direction is suppressed as compared with the case of the comparative form is presumed as follows. That is, in the case of the comparative embodiment, as described above, in the manufacturing process, the roof member is manufactured without bending the portion of the blank 30 where the flange 6a is formed. Here, FIG. 8 is a schematic diagram showing the force (arrow in the figure) acting on the portion of the blank 30 where the flange 6a is formed during the second step in the comparative embodiment. A region E between two two-dot chain lines is a portion where the top plate 2 and the vertical walls 4a and 4b in the blank 30 are formed. As shown in FIG. 8, in the case of the comparative embodiment, the portion of the blank 30 where the flange 6a is formed flows into the groove 21a side (the ridge line curved convexly toward the groove 21a) in the second step. At the time, it is pulled in the normal direction from the ridgeline. As a result, in the case of the comparative embodiment, tensile stress acts in the longitudinal direction on the flange 6a of the roof member manufactured after the second step. As a result, it is presumed that the roof member of the comparative form is bent due to the spring back of the flange 6a. On the other hand, in the case of the present embodiment, in the first stage, as shown in FIG. 9, the portion of the blank 30 where the flange 6a is formed is bent. At that time, the portion of the blank 30 where the flange 6a is formed is stretched in the direction of the arrow in FIG. 9 (in this case, the portion of the blank 30 where the flange 6a is formed is plastically deformed). And in the case of this embodiment, after the part in which the flange 6a in the blank 30 is formed is extended by the 1st process, the roof member 1 is press-molded by the 2nd process, and is manufactured. Therefore, in the case of this embodiment, compared with the case of a comparative form, when the part in which the flange 6a in the blank 30 is formed flows in into the groove | channel 21a side at a 2nd process, it is hard to be extended in a longitudinal direction. As a result, in the case of this embodiment, it is presumed that the tensile stress acting in the longitudinal direction of the flange 6a of the roof member 1 is reduced as compared with the case of the comparative embodiment.

  Therefore, the roof member 1 manufactured by the manufacturing method according to the present embodiment is larger in the thickness direction of the vertical wall 6a than the case where the portion of the blank 30 where the flange 6a is formed is not bent. The occurrence of bending is suppressed.

  Further, in the case of the present embodiment, in the first stage, it is a part of the blank 30 in the longitudinal direction with respect to the portion where the flange 6a is formed, and the short direction of the portion with the smallest curvature radius in the edge 21a31 of the groove 21a ( The portion on the (normal direction) side is bent (see FIG. 9). The portion with the smallest radius of curvature at the edge 21a31 of the groove 21a in the roof member 1 is considered to be a portion that is more easily springback than the other portions. In the case of this embodiment, as described above, the portion on the short side direction (normal direction) side of the portion with the smallest curvature radius in the edge 21a31 of the groove 21a among the portions where the flange 6a in the blank 30 is formed is It is extended in the direction of the arrow in FIG. Therefore, the roof member 1 manufactured by the manufacturing method according to the present embodiment has the short direction (method) of the portion other than the portion having the smallest curvature radius in the edge 21a31 of the groove 21a among the portions of the blank 30 where the flange 6a is formed. Compared with the case where the portion on the (linear direction) side is bent, the occurrence of bending of the vertical wall 6a in the thickness direction is suppressed.

  In the case of the present embodiment, the bent portion of the blank 30 is not simply bent, but is deformed so as to be continuously convex or concave in the direction in which the blank 30 flows in the second step. Is done. Therefore, in the case of this embodiment, it can be said that the blank 30 easily flows in in the second step.

  The above is description about the effect | action of this embodiment.

<< Second Embodiment >>
Next, a second embodiment will be described. First, the configuration of the roof member 1A (see FIG. 10) of the present embodiment will be described. Next, the configuration of the press device (not shown) of this embodiment will be described. Next, a method for manufacturing the roof member 1A of the present embodiment will be described. Next, the operation of this embodiment will be described. In the following description, portions of the present embodiment that are different from the first embodiment will be described. Further, in the description of the present embodiment, when the same parts as the parts used in the first embodiment are used, the reference numerals of the parts are used as they are even when not shown.

<Configuration of roof member>
First, the configuration of the roof member 1A of the present embodiment will be described with reference to the drawings. Here, the roof member 1A is an example of a press-formed product and a specific press-formed product.

  Unlike the roof member 1 (see FIG. 1) of the first embodiment, the roof member 1A (see FIG. 10) of the present embodiment is not open at both ends. Therefore, the vertical wall 4c is connected to one end in the longitudinal direction of the top plate 2, the vertical wall 4a and the vertical wall 4b, and the vertical wall 4d is connected to the other longitudinal end of the top plate 2, the vertical wall 4a and the vertical wall 4b. In addition, a flange 6c is connected to one end of the vertical wall 4c, the flange 6a, and the flange 6b, and a flange 6d is connected to the other end of the vertical wall 4d, the flange 6a, and the flange 6b. That is, the roof member 1A is a so-called dish-shaped member. The roof member 1A of the present embodiment has the same configuration as the roof member 1 of the first embodiment except for the above points.

<Configuration of press machine>
Next, the press apparatus (not shown) of this embodiment is demonstrated. The press apparatus of this embodiment is for manufacturing the roof member 1A.

  Unlike the press device 18 of the first embodiment, the press device of the present embodiment is formed with inclined walls for forming the vertical walls 4c and 4d at both ends in the longitudinal direction in the upper groove. . The shape of the lower mold is a shape that fits into the groove. The press device of this embodiment has the same configuration as the press device 18 of the first embodiment except for the above points.

<Manufacturing method of roof member>
Next, a method for manufacturing the roof member 1A of the present embodiment will be described. The manufacturing method of the roof member 1A of the present embodiment is the same as that of the first embodiment except that the press device of the present embodiment is used instead of the press device 18 of the first embodiment.

<Action>
The operation of this embodiment is the same as that of the first embodiment (see the table in FIG. 12 described later).

  The above is the description of the second embodiment.

<Example>
Next, examples and comparative examples will be described with reference to the drawings. In addition, in the following description, when the code | symbol of components etc. similar to the code | symbol of components etc. used by this embodiment and the comparison form is used, the code | symbol of the components etc. is used as it is.

<Description of the table in FIG. 11>
In the table of FIG. 11, simulation conditions and evaluation results for Examples 1 to 5 of the first embodiment and Comparative Examples 1 to 4 of the comparative example described above are described. Here, the table of FIG. 11 will be described. The plate thickness is the thickness of the blank 30 used in the simulation. The strength is the tensile strength of the blank 30 used for the simulation. Note that the holder offset amount, the tip end bend, the rear end bend and the average bend amount are as described above. Here, “None” in the column of the holder offset amount means that the concave surface 21c is not formed in the upper mold 21 of the press device 18A, and the first holder 23 has It means that the convex surface 23b is not formed.

<Evaluation results and discussion>
From the table of FIG. 11, the roof member 1 of Examples 1 to 5 is less bent (the average amount of bending is smaller) when the plate thickness and strength are the same as those of the roof members of Comparative Examples 1 to 4. I understand that. From the above, Examples 2 to 5, which are examples of the present embodiment (Example 1), are compared with Comparative Examples (Comparative Examples 2 to 4) which are examples of Comparative Mode (Comparative Example 1). It is thought that there exists an effect | action of this embodiment.

<Description of Table in FIG. 12>
In the table of FIG. 12, Example 6 of the second embodiment and its comparative example (when the roof member having the same shape as the roof member 1A of FIG. 10 is manufactured without bending the blank 30 in the first step) The simulation conditions and evaluation results for Comparative Example 5 are described.

<Evaluation results and discussion>
From the table of FIG. 12, the roof member 1A of Example 6 is less bent (the average amount of bending is smaller) than the roof member of Comparative Example 5 even though the plate thickness and strength are the same conditions. I understand. From the above, it is considered that Example 6, which is an example of the second embodiment, exhibits the same action as that of the first embodiment as compared with Comparative Example 5.

  As described above, the present invention has been described with respect to specific embodiments. However, the technical scope of the present invention includes forms other than the above-described embodiments. For example, the following forms are also included in the technical scope of the present invention.

  In the first and second embodiments and examples, it has been described that an example of a press-formed product is a roof member. However, as long as it is a product manufactured by the method including the first step and the second step of the present embodiment, the press-formed product may be an automotive part other than the roof member. Moreover, as long as it is a thing manufactured by the method containing the 1st process and 2nd process of this embodiment, components other than components for motor vehicles may be sufficient.

  In the first and second embodiments and examples, it has been described that the concave surface 21 c is formed on the upper mold 21 and the convex surface 23 b is formed on the first holder 23. However, if the portion of the blank 30 where the flange 6a is formed can be bent in the first step before the second step, the upper mold 21 has the convex surface 23b and the first holder 23 has the concave surface 21c. May be. Moreover, if the part in which the flange 6a in the blank 30 is formed in the 1st process before a 2nd process can be bent, the shape of the recessed surface 21c and the convex surface 23b will be 1st, 2nd Embodiment, and an Example. The shape may be different from the above case.

  In the first and second embodiments and examples, it has been described that in the first step, the upper mold 21 and the first holder 23 are bent with the blank 30 interposed therebetween. However, the roof member 1, 1 </ b> A may be manufactured by performing only the second step with the press device 18 after bending the portion of the blank 30 where the flange 6 a is formed in advance without using the press device 18.

  The press-formed product of the first and second embodiments and examples has been described as including a top plate, two vertical walls, and two flanges. However, the press-formed product is connected to a curved wall that is curved in a convex shape with respect to the thickness direction, and one end is connected to the curved end of the curved wall, and the curved wall is convex in the thickness direction. As long as it is configured to include a curved side and a flange disposed on the opposite side, the presence or absence of other components does not matter. For example, the press-molded product included in the technical scope of the present invention may have a top plate, a curved wall, and a flange that does not have another vertical wall facing the curved wall. Good. Further, the press-molded product included in the technical scope of the present invention may not have a top plate. Specifically, if a press-molded product including a curved wall curved in the longitudinal direction and a flange connected to the curved wall is manufactured by the mold 20B and the press device 18B shown in FIGS. 13 and 14, for example, The shape of the cross section of the groove 21a of the upper mold 21 may not have both ends in the short direction of the bottom 21a1 of the groove, that is, may be an arc shape. Of the components shown in FIGS. 13 and 14, the components used in the first embodiment and the second embodiment are denoted by the same reference numerals.

1 Roof member (example of press-formed product)
4a Vertical wall (an example of a curved wall)
6a Flange 18 Press device 21 Upper die (example of first die)
22 Lower mold (example of punch)
21a Groove (example of die hole)
21b Mold closing surface (example of first surface)
21c Recessed surface (example of second surface)
30 blank

Claims (3)

Using a die, a punch, and a holder, a curved wall that is curved in a convex shape with respect to the plate thickness direction, and one end connected to the curved end of the curved wall, and the curved wall is convex in the plate thickness direction. A method of manufacturing a press-molded article comprising a side curved in a shape and a flange disposed on the opposite side,
A first step of bending a portion of the blank where the flange is formed at an inclination angle of 60 ° or less;
After the first step, the blank is pressed with the die and the punch in a state where the portion is sandwiched between the die and the holder, and the curved wall and the flange are formed on the blank. Process,
A method for manufacturing a press-molded article including: In the first step, the part is bent between the die and the holder, and the part is bent.
A method for producing the press-formed product according to claim 1. A die hole, a die shoulder forming a ridge line that curves convexly toward the die hole, a first surface adjacent to the die shoulder on the opposite side of the die hole across the die shoulder, and a method of the ridge line A die comprising a plate pressing surface provided with a convex or concave second surface having an inclination angle of 60 ° or less with respect to the first surface on the line;
A holder comprising a plate pressing surface of a shape corresponding to the plate pressing surface of the die;
Press device.

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