[Name of Document] DESCRIPTION [Title of the Invention] METHOD AND PRESS-FORMING APPARATUS FOR MANUFACTURING STRUCTURAL MEMBER FOR AUTOMOTIVE BODY 5 [Teclmical Field] [0001] The present invention relates to a method and a press-forming apparatus for manufacturing a structural member for an automotive body, and more particularly to a method and a press-forming apparatus for manufacturing a structural member for 10 an automotive body as a press-formed product made of a steel sheet. [Background Art] [0002] An automotive body is generally formed of structural members mainly 15 including vehicle longitudinal members that are disposed along a vehicle longitudinal direction and vehicle widthwise members that are disposed along a vehicle widthwise direction. The structural members such as vehicle longitudinal members and vehicle widthwise members, each of which is connected to other members by a flange that is formed at either end of each structural member, ensure 20 the rigidity required"for1he automotive body, and bear the load. [0003] The structural member for the automotive body requires, for example, a high deformation tolerance against the load acting along the axial direction of the structural member, and a high torsional rigidity. A thim1er high-tensile steel sheet 25 having high strength, for example, high tensile strength (high-strength steel sheet or high tensile strength steel sheet), has been increasingly used in recent years as a 2 material for such a structural member in an aim to reduce automotive body weight and improve collision safety. For heavy automobiles such as trucks, however, structural members made of steel sheets of large thickness may be used. [0004] 5 For example, a floor cross member, which is used as a structural member to reinforce a floor of an automotive body, has a cross section substantially shaped like a gutter and is connected to side sills or other vehicle longitudinal members via outward flanges formed at both ends of the floor cross member. It is important for such a floor cross member to have an increased bonding strength with other members 10 and an increased torsional rigidity to ensure the automotive body rigidity and better load transfer property in a case where an impact load is applied. [0005) Patent Literatures I to 3 disclose manufacturing methods for structural members for automotive bodies to eliminate defects in the shape fixation of press 15 formed products using high strength materials by getting creative with pad mechanisms used in dies. The manufacturing methods described in these Patent Literatures have attempted to improve in shape fixability after press forming by intentionally generating deflection of a material during forming depending on the positional relationship between the top of a punch and a flat pad of only a part that 20 faces a flat part·ofthe·l'op of the punch. [0006) Further, Patent Literature 4 discloses a flange-shaping die for shaping a flange in an end of a panel product for an automotive body. The flange shaping die can shape a center flange continuing to a center wall and a sideward-protruding 25 flange continuing to a side wall by using the same die in one-time step. Patent Literature 4 also discloses an example in which a blank material is folded while a 3 portion of the blank material to be formed into the center wall is held by a pad. [Prior Art Literatures] [Patent Literatures] 5 [0007] 10 [Patent Literature I] JP 4438468B [Patent Literature 2] JP 2009-255116A [Patent Literature 3] JP 2012-0SJOOSA [Patent Literature 4] JP HS-23761A [Summary of the Invention] [Problem(s) to Be Solved by the Invention] [0008] In order to improve the automotive body rigidity and the load transfer 15 property while an impact load is applied, it is preferable that an outward flange to be formed in an end of a structural member is a continuous flange, and the structural member is jointed to another member via the continuous flange. In other words, it is preferable, as will be described later, that the outward flange is formed also on a peripheral part of a ridge of the structural member so that the outward flange is 20 formed continuously over the ridge and also over at least a part of a gutter bottom and a vertical wall in an end of the sttucturalmember. [0009] However, a high-tensile steel sheet, which has a low ductility as compared to a low strength steel sheet such as a mild steel sheet, poses a problem of fracturing 25 during press forming. In addition, a large pressing load is required to press form the high-tensile steel sheet or a steel sheet having a large thickness. It is not easy, 4 however, to increase the pressing load to be able to exert a sufficient tensile force on a forming material. Another problem occurring in press forming the forming material made of the high-tensile steel sheet or the steel sheet having a large thickness is that wrinkles are generated easily. 5 [0010] For the above reasons, forming an outward continuous flange in an end of the structural member using conventional press forming methods tends to generate extension cracks at the edge of a ridge flange and wrinkles in the vicinity of the base of the ridge flange during press forming. Consequently, it has been difficult to 10 obtain a desired shape as an outward continuous flange by using press forming methods known in the art. [0011] As described above, it is difficult to manufacture a structural member having an outward continuous flange from a forming material such as a high-tensile 15 steel sheet or a thick steel sheet without generating the aforementioned wrinkles and cracks because of the technical constraints in the press forming. Consequently, at present, a notch has had to be provided in place of a ridge flange to compensate such difficulty in press forming. Such a notch has been a cause to deteriorate properties such as torsional rigidity and load transfer property. 20 [0012] From this point of view, known techniques disclosed in Patent Literatures 1 to 4 do not take into account formation of an outward continuous flange while suppressing the generation of cracking in the edge of the ridge flange or wrinkling near the base of the ridge flange during the press forming. Consequently, it is still 25 difficult, by using known techniques disclosed in Patent Literatures 1 to 4, to carry out press forming of a structural member that is made of a high-strength steel sheet 5 or high-tensile steel sheet, and that has a substantially gutter-shaped cross section and an outward continuous flange of desired shape in an end. [0013] Incidentally, the term "outward flange" as used herein refers to a flange 5 formed in the way that an end of a press formed product having a substantially gutter-shaped cross section is bent outwardly from the gutter. The term "outward continuous flange" refers to an outward flange continuously formed over the ridge and also over at least a part of the gutter bottom and the vettical wall in the end of the press formed product. Further, the term "ridge flange" as used herein refers to a 10 flange formed on the periphery of the ridge in the outward continuous flange. [0014] Furthermore, the phrase "provide a notch in a flange" as used herein is meant to provide. a notch formed in the whole width direction of the flange, which makes the flange discontinuous. The term "the width of a flange" is used to have 15 the same meaning as the height of the flange. When the width of the flange is made small pmtially but a part of the flange still remains, the notch is not meant to be provided in the flange. [0015] An object of the present invention is to provide a method and a press- 20 forming apparatus·for manufacturing a structural member for an automotive body, which can reduce the generation of cracking in the edge of the ridge flange and wrinkling near the base of the ridge flange and can suppress an increase in the pad load, while press forming the structural member that is made of a high-tensile steel sheet or a thick steel sheet and that has a substantially gutter-shaped cross section 25 and an outward continuous flange in an end of the structural member. [Means for Solving the Problem(s)] ~I 6 [0016] In order to solve the problems, according to an aspect of the present invention, there is provided a method for manufacturing a structural member for an automotive body, the structural member being formed by pressing a forming material 5 made of a steel sheet by using a press-forming apparatus having a punch, a die, and a pad facing the punch, the structural member extending in a predetermined direction, having a substantially gutter-shaped cross section intersecting the predetermined direction, and including a gutter bottom, a ridge continuing to the gutter bottom, a vetiical wall continuing to the ridge, and an outward continuous flange being 10 continuously formed along at least one end in the predetermined direction, the one end at least including a part of the ridge, a pati of the gutter bottom, and a part of the vertical wall, the method including: a first step in which the pad presses the forming material against the punch to raise a portion corresponding to a flange to be formed in ends of at least the gutter bottom and the ridge in a direction opposite to the 15 pressing direction, and the punch and the die carry out press forming to form an intermediate product, wllile the pad bends an end of a portion to be formed into the ridge in the pressing direction and restrains at least a part of the end, and a region other than an end in a portion to be formed into the gutter bottom remains umestrained; and a second step in which the intermediate product is futiher pressed 20 to form the structutahnember for the automotive body. [0017] 25 At least a part of the end of the portion to be formed into the gutter bottom may be umestrained in the first step. [00 18] The whole portion to be formed into the gutter bottom and at least a part of the portion corresponding to the flange to be formed in the end of the gutter bottom, 7 the part continuing to the portion to be formed into the gutter bottom, may remain umestrained in the first step. [0019] A portion of at least 1/2 length of a perimeter of a cross section in the end of 5 the portion to be formed into the ridge, the 1/2 length starting from a border between the pmiion to be formed into the ridge and the portion to be formed into the gutter bottom, may remain unrestrained in the first step. [0020] The punch used in the first step may have a shoulder having a surface for 10 forming the ridge, and at least a portion of the shoulder corresponding to the end in the predetermined direction may have a curvature radius ranging from 2 mm to 45 mm. [0021] The steel sheet may be a steel sheet of 2.3 mm or more in thickness or a 15 high-tensile steel sheet of 440 MPa or more in tensile strength. [0022] In order to solve the problems, according to m1o~her aspect of the present invention, there is provided a press-forming apparatus used for manufacturing a structural member for an automotive body, the structural member extending in a 20 predetermined ··dire-ction, having a substantially gutter-shaped cross section intersecting the predetermined direction, and including a gutter bottom, a ridge continuing to the gutter bottom, a vertical wall continuing to the ridge, and an outward continuous flange being continuously formed along at least one end in the predetermined direction, the one end at least including a part of the ridge, a part of 25 the gutter bottom, and a pmi of the vertical wall, the press-forming apparatus including: a punch; a die; and a pad facing the punch, the punch and the die carrying 8 out press forming while the pad and the punch restraining a forming material made of a steel sheet. The pad presses the forming material to bend an end of a portion to be formed into the ridge in the pressing direction, and restrains at least a part of the end while a region other than an end in a pottion to be formed into the gutter bottom 5 remains unrestrained. [0023] The pad may leave at least a part of the end of the portion to be formed into the gutter bottom umestrained. [0024] 10 The pad may leave umestrained the whole portion to be formed into the gutter bottom and at least a patt of the pmtion corresponding to the flange to be formed in the end of the gutter bottom, the pati continuing to the portion to be formed into the . gutter bottom. [0025] 15 The pad may leave unrestrained a portion of at least 1/2 length of a perimeter of a cross section in the end of the portion to be formed into the ridge, the 1/2 length starting from a border between the portion to be formed into the ridge and the portion to be formed into the gutter bottom. [0026] 20 The punch-may have a shoulder having a surface for forming the ridge, and at least a portion of the shoulder corresponding to the end in the predetermined direction may have a curvature radius ranging from 2 mm to 45 nun. [Effect(s) of the Invention] [0027] 25 During press forming in the first step according to the present invention, an end of the portion to be formed into the ridge is bent, and then restrained, by the pad 9 while the region other than the end of the portion to be formed into a gutter bottom remains unrestrained. Consequently, the load per unit area applied to the area restrained by the pad increases without increasing the pad load. In this way, the end of the potiion to be formed into the ridge is securely restrained by the pad, and the 5 end of the ridge is formed by projecting outward the steel sheet material in the region that is pressed by the pad. This rest)!ts in restraining the movement of the steel sheet material in the area surrounding the region pressed by the pad, and also suppressing an increase in the pad load, while obtaining the press formed product that restrains the generation of cracks at the edge of the outward continuous flange 10 and wrinkles in the vicinity of the base of the outward continuous flange. [0028] The stmctural member manufactured by the press forming, which has a substantially gutter-shaped cross section and an outward continuous flange formed in the end thereof and is made of a high-tensile steel sheet or a thick steel sheet, can 15 exhibit an improved torsional rigidity and load transfer propetiy, thanks to having an outward continuous flange of desired shape. In addition, such structural member can join to other members using the whole area of the outward continuous flange including the ridge flanges, which leads to a large increase in the strength and rigidity of a jointed structure including the structural member. Consequently, this 20 expands the po·ssibility of applying steel sheets, for example, steel sheets having a thickness of 2.3 mm or more or having a tensile strength of 440 MPa or more, to structural members for automotive bodies. 25 [Brief Description of the Drawing(s)] [0029] [FIG. I] FIG. I (a) is a perspective vtew illustrating an example of a structural member to be manufactured using a method and a press-forming apparatus 10 for manufacturing a structural member for an automotive body according to an embodiment of the present invention, and FIG. I (b) is a view on the arrow A in FIG. I (a). (FIG. 2] FIG. 2 illustrates an example of a structural member having notches 5 in an outward flange provided at a gutter bottom and a vertical wall. (FIG. 3] FIG. 3 is a schematic view illustrating a jointed structure. [FIG. 4] FIG. 4 is a sectional view outlining a schematic structure of a pressforming apparatus according to the present embodiment. [FIG. 5] FIG. 5 a perspective view illustrating a schematic stmcture of a 10 press-forming apparatus according to the present embodiment. [FIG. 6] FIG. 6 (a) is a perspective view schematically illustrating a state of a forming material restrained by a ridge pad, and FIG. 6(b) is a schematic view illustrating a state of a forming material restrained by a ridge pad. [FIG. 7] FIG. 7 (a) is a sectional view schematically illustrating a state of a 15 forming material restrained by a pad known in the art, and FIG. 7(b) is a sectional view schematically illustrating a state of a forming material restrained by a pad known in the art. [FIG. 8] FIG. 8 is a perspective view illustrating a state in which a whole portion to be formed into a ridge in the vicinity of an outward flange is restrained. 20 [FIG. -9] FIG. 9 is a perspective view illustrating a state in which a curved surface rising from a gutter bottom to an outward flange is restrained. [FIG. 10] FIG. 10 is a perspective view illustrating a state in which a whole gutter bottom in the vicinity of an outward flange is restrained. [FIG. II] FIG. 11 is a sectional view illustrating another structure example 25 of the ridge pad. [FIG. I 2] FIG. 12 is a schematic view illustrating a step in which a ridge pad 11 restrains a forming material. [FIG. 13] FIG. 13 is a schematic view illustrating a step in which a die presses a forming material. [FIG. 14] FIG. 14 is a characteristic diagram illustrating a relationship 5 between a curvature radius of a shoulder of a punch and a maximum value in a decrease rate of sheet thickness of a ridge flange. 10 [Mode( s) for Carrying out the Invention] [0030] Hereinafter, a prefetTed embodiment of the present disclosure will be described in detail with reference to the appended drawings. In this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these stmctural elements is omitted. 15 [0031] A method and a press-forming apparatus for manufacturing a structural member for an automotive body according to an embodiment of the present invention are provided to manufacture a structural member having an outward 20 continuous flange of desired shape. Accordingly, a structural member manufactured according to the present embodiment will be first explained. [0032] FIG. 1 illustrates an example of a structural member 1 to be manufactured using a method and a press-forming apparatus for manufacturing a structural member 25 for an automotive body according to the present embodiment. FIG. I (a) is a perspective view and FIG. l(b) is a view on the arrow A in FIG. 1 (a), both of which 12 illustrate the structural member I. The structural member 1 is formed extending in a predetermined direction designated by the anow X in FIG. 1 (a) (which is a direction substantially perpendicular to the plain of the paper of FIG. l(b), in other words, an axial direction). The structural member 1 is a press formed product made 5 of a high-tensile steel sheet and having a sheet thickness of 2.3 mm or more and a tensile strength of 440 MPa or more measured by tensile testing in accordance with JIS Z 2241. The structural member I illustrated in FIG. I (a) has a predetermined direction that is the longitudinal direction of the structural member 1. The predetermined direction, however, is not limited to the longitudinal direction of the 10 structural member I. [0033] The structural member 1 is used, for example, as a floor cross member, a side sill, a fi·ont . .side. member, a floor tunnel brace, or as a pati of these members. When the structural member I is used as a reinforcement member for the floor cross 15 member, the side sill, the front side member, the floor tunnel or other members, a high-strength steel sheet having a tensile strength preferably of S90 MPa or more, and more preferably of780 MPa or more, is used as a forming material. [0034] As illustrated in FIG. 1, the structural member 1 has a substantially hat- 20 shaped cross ·section:·an:rl includes a gutter bottom 2, ridges 3a, 3b continuing to the gutter bottom 2, vertical walls 4a, 4b continuing to the ridges 3a, 3b, curved sections Sa, Sb continuing to the vertical walls 4a, 4b, and flanges 6a, 6b continuing to the curved sections Sa, 5b. The substantially hat-shaped cross section is a mode of a substantially gutter-shaped cross section. The two ridges 3a, 3b are continuously 25 formed at both ends of the gutter bottom 2 in the width direction. The two vertical walls 4a, 4b are formed continuing to the two ridges 3a, 3b, respectively. The two 13 curved sections Sa, Sb arc formed continuing to the two vertical walls 4a, 4b, respectively. The two flanges 6a, 6b are formed continuing to the two curved sections Sa, Sb, respectively. The curved sections Sa, Sb continuing to the vertical walls 4a, 4b and the flanges 6a, 6b continuing to the curved sections Sa, Sb may be 5 omitted in the structural member 1 that is manufactured using a method and a pressforming apparatus for manufacturing a structural member for an automotive body according to the present embodiment. [003S] An outward continuous flange 7 is formed on the periphery of a longitudinal 10 end of the structural member 1 along the gutter bottom 2, the ridges 3a, 3b, and the vettical walls 4a, 4b. The structural member 1 is a press formed product having the ridge flanges 7a, 7b and not having notches in portions corresponding to the periphery ofthe.ridges,3.a, 3b, which is different from press formed products known in the ati. Since the structural member 1 includes the outward continuous flange 7, 15 the structural member 1 can join to other members also at the ridge flanges 7a, 7b using spot welding or the like. Consequently, tltis increases torsional rigidity when a load in an axial rotational direction is applied to the structural member I. The outward continuous flange 7 included in the structural member 1 alleviates stress concentration in the ends of the ridges 3a, 3b when an axial load is applied to the 20 structural member l. ·This improves the load transfer property of the structural member I. [0036] As used herein, the term "end in the predetermined direction (longitudinal direction or axial direction)" is meant to include a curved rising surface between the 25 outward continuous flange 7 and the gutter bottom 2, the ridges 3a, 3b, and the vettical walls 4a, 4b, etc., and also include a region within a flange-width length 14 along the predetermined direction from the border with the outward continuous flange 7. [0037] The flange width of the outward continuous flange 7 is preferably 2 mm or 5 more in the region that is not jointed to connection with another member. For the region that is jointed to co1111ection with another member using spot welding, laser welding, etc., the flange width of the outward continuous flange 7 is preferably I 0 mm or more, and more preferably 15 nun or more. According to a method for manufacturing a structural member for an automotive body of the present 10 embodiment, a structural member I of desired shape having the outward continuous flange 7 can be obtained even though the flange width is made larger. The flange width of the outward continuous flange 7 can be suitably adjusted by modifying the shape of a developed blank (a forming material) 16, which will be described later. [0038] 15 The structural member I in FIG. I is a press formed product having a substantially hat-shaped cross section. The cross sectional shape of the sttuctural member I, however, is not limited to the shape like a hat. A method and a pressforming apparatus for manufacturing a structural member for an automotive body according to the present embodiment is applicable to manufacturing of a press 20 formed product that has at least a gutter bottom 2, ridges 3a, 3b, and vertical walls 4a, 4b, and also has an outward continuous flange 7 in the end in the predetermined direction. The outward continuous flange 7 of the structural member 1 in FIG. I is continuously formed along the whole periphery of the end in the longitudinal direction. However, it may be discontinuous in portions corresponding to the 25 peripheries of the gutter bottom 2 or the vertical walls 4a, 4b. As shown in FIG. 2, for example, notches 8 may be provided in a pati of the flange along the gutter 15 bottom 2 and the vertical walls 4a, 4b. [0039] A forming material of the structural member I is not limited to a steel sheet having a thickness of 2.3 mm or more or a tensile strength of 440 MPa or more. 5 The steel sheet may have a thickness of less than 2.3 mm or a tensile strength of less than 440 MPa. However, a method and a press-forming apparatus for manufacturing a structural member for an automotive body according to the present embodiment is especially effective when the forming material is a steel sheet having a thickness of 2.3 111111 or more or a steel sheet having a tensile strength of 440 MPa 10 or more that are difficult to be formed into a desired shape by using pressing methods known in the art . Although upper limits of sheet thickness and tensile strength are not specified, typical upper limits of sheet thickness and tensile strength are about 15 111111 and about 1310 MPa. 15 [0040] The structural member 1 can be jointed to another member via the outward continuous flange 7 formed in the end of the structural member 1, and then the structural member 1 can be used as a jointed structure. FIG. 3 illustrates a structure example of a jointed structure 20. The jointed structure 20 is formed of the structural member 1 that is spot -welded to another steel sheet member I 0 via the 20 outward continuous flange 7 formed in the end of the structural member I. In the jointed shucture 20, the flange width of the outward continuous flange 7 of the structural member 1 is 1 Omm or more. The jointed stmcture 20 is spot-welded at a plurality of spots, which are equally spaced with each other, over the whole outward continuous flange 7. Consequently, the jointed structure 20 has an increased 25 strength in the joint, and provides an excellent torsional rigidity and an excellent load transfer property along the axial direction of the stmcturalmember I. 16 [0041] Incidentally, although the structural member I illustrated in FIG. 1 has an outward continuous flange 7 at one end in the longitudinal direction, the stmctural member 1 may have the outward continuous flanges 7 at both ends in the 5 longitudinal direction. [0042] <2. Method and Press-forming Apparatus for Manufacturing Stmctural Member for Automotive Body> Next, a method and a press-forming apparatus for manufacturing a stmctural 10 member for an automotive body according to the present embodiment are described. As described in the foregoing, a method and a press-forming apparatus for manufacturing a structural member for an automotive body according to the present embodiment are. the method and the apparatus that are used to manufacture the structural member 1 having the outward continuous flange 7 formed on at least one 15 end in the predetermined direction as illustrated in FIG. 1. Now, a method for manufacturing a structural member for an automotive body will be outlined hereafter, and then details of a method and a press-forming apparatus for manufacturing a structural member for an automotive body according to the present embodiment are described. 20 [0043] (2-1. Outline of Manufacturing Method) A method for manufacturing a structural member for an automotive body according to the present embodiment will now be outlined. The manufacturing method of a press formed product according to the present embodiment includes a 25 first step using a first press-forming apparatus and a second step using a second press-forming apparatus. 17 [0044] The first step is carried out using the first press-forming apparatus. The first press-forming apparatus corresponds to a press-forming apparatus according to the present embodiment, which will be described later. In the first step, a pad 5 presses a forming material against a punch so that a .portion corresponding to a flange, which will be formed at least in ends of the gutter bottom and the ridges, is raised in an opposite direction to the pressing direction. In addition, the pad bends the end of the portion to be formed into the ridge in the pressing direction, and at least a part of the end is restrained. A region other than the end in the end of the portion to be 10 formed into a gutter bottom is made unrestrained. With the forming material being restrained by the pad, the punch and die catTy out press forming to form an intermediate product. [0045] . ~.;·.·~ The second step is carried out usmg a second press-forming apparatus, 15 which is different from the first press-forming apparatus. In the first step, the pad restrains at least the end of the ridge so that a portion below the pad in the pressing direction remains unformed. Accordingly, the structural member is formed by pressing the intermediate product using the second press-forming apparatus in the second step. 20 [0046] The second press-forming apparatus may be a type of machine capable of pressing what has remained unformed by the first press-forming apparatus. In particular, the second press-forming apparatus may be a type of machine capable of pressing the portion that has not been pressed by the pad and the die among portions 25 to be formed into the gutter bottom, the ridges, and the vetiical wall. Further, the second press-forming apparatus may be a type of machine that presses a pm1ion of 18 the outward continuous flange that has not been formed by the first press-forming apparatus. A known press-forming apparatus having a die and punch can be used as such second press-forming apparatus. [0047] 5 (2-2. Press-forming Apparatus) Now, the press-forming apparatus according to the present embodiment will be described. As described in the foregoing, the press-forming apparatus according to the present embodiment is the first press-forming apparatus used in the first step to form the intermediate product. FIG. 4 and FIG. 5 schematically illustrates a 10 structure example of a press-forming apparatus I I according to the present embodiment. FIG. 4 is a sectional view outlining a part of the first press-forming apparatus I I that forms the end region of the structural member I. FIG. 4 illustrates a state in which.a forming material 16 is placed on a punch 13 before press forming starts. FIG. 5 is an exploded perspective view outlining a stmcture of the first press- 15 forming apparatus 11. Further, FIG. 6 (a) and FIG. 6 (b) are a perspective view and a sectional view, both of which schematically illustrate a state in which the forming materia116 is restrained by a pad 15. [0048] The first press-forming apparatus 11 has a punch 13, a die 14, and a pad 15 20 that presses a·fonning material 16 against the punch 13 and restrains the forming material 16. The first press-forming apparatus 11 is basically configured to press the forming material 16 by moving the die 14 to the punch 13 with the forming material 16 being restrained by the pad 15 and the punch 13. 25 [0049] The punch 13 has a punch surface 13b having a shape corresponding to a substantially gutter-shaped cross section of the structural member I to be formed, 19 and a side wall 13a disposed at a longitudinal end of the punch 13. The punch surface 13b has an upper surface 13ba and shoulders 13bb for forming the ridges. The side wall 13a is the part which will form the outward continuous flange 7 by collaborating with a flange forming pmi 15-3 ofthe pad 15. 5 [0050] In each shoulder 13bb of the punch 13, at least the longitudinal end of the shoulder 13bb, which is proximate to the side wall !3a, preferably has a curvatnre radius Rp of 2 mm or more. The curvature radius Rp at the po1iion of the shoulder 13bb being less than 2 nun makes it difficult to disperse the strain generated in the 10 end of each pmiion to be formed into the ridges 3a, 3b in the forming material 16 when the end is restrained by the pad 15. In contrast, if the curvature radius Rp at the portion of the shoulder 13bb exceeds 45 ll1lll, the strain is relatively alleviated even though - 32 As described above, in accordance with the method for manufacturing a structural member for an automotive body, which includes a press-forming apparatus (first press-forming apparatus) 11 according to the present embodiment, and the first step using the first press-forming apparatus 11, there is obtained the structural 5 member 1 having the outward continuous flange 7 formed from the gutter bottom 2 to each vettical wall 4a and 4b in the end in the predetermined direction. In the first step, the ridge pad 15 bends and restrains the ends of pmtions to be formed into the ridges 3a, 3 b in the pressing direction. Meanwhile, regions except the end in the portion to be formed into the gutter bottom 2 are left unrestrained in the first step. 10 Consequently, the deflection of the gutter bottom 2 is induced, and the perimeter of the cross section of the gutter bottom 2 and the ridges 3a, 3b becomes longer, which reduces cracking in the edge of the ridge flange 7. [0086] In addition, the pmtion to be formed into the gutter bottom 2 is left 15 umestrained so that the load per unit area applied to the region restrained by the ridge pad 15 increases without increasing the pad load considerably. Accordingly, the ends of the portions to be formed into the ridges 3a, 3b are securely restrained by the ridge pad 15, and the portion of the steel sheet material that is pressed by the ridge pad 15 is made to project outward to form the ends of the ridges. This results in 20 restraining the movement of the steel sheet material in the area sunounding the portions pressed by the ridge pad 15, and also suppressing an increase in the pad load, while obtaining the press formed product having reduced cracks in the edge of the outward continuous flange 7 and reduced wrinkles in the vicinity of the base of the outward continuous flange 7. 25 [0087] According to the present embodiment, as described above, the elongation 33 and slu·inkage deformation of the surrounding material, which cause cracking in the edge and wrinkling near the base of each ridge flange 7a, 7b, will be reduced even though a forming material 16 made of a steel sheet having a sheet thickness of 2.3 mm or more or a high-tensile steel sheet having a tensile strength of 440 MPa or 5 more is used. Composing structural members for an automotive body from the press formed products that are formed in the above described way enables an improvement in the rigidity and in the load transfer property in the case where an impact load is applied. 10 [0088] A preferable embodiment has been described so far with reference to the accompanied drawings. The present invention, however, is not limited to the above described example. It will be evident that those skilled in the mt to which the present invention pertains may conceive various alternatives and modifications while remaining within the scope of the technical idea as described in the claims. It should 15 be understood that such alternatives and modifications apparently fall within the 20 technical scope of the present invention. [Example] [0089] Examples according to the present invention will now be described. [0090] ( 1) Examples 1, 2 and Comparative Example 1 In Example 1, a structural member 1 was manufactured using a ridge pad 15 as illustrated in FIGs. 4 and 5 by the manufacturing method according to the present 25 embodiment. In Example 1, the region of 1/2 of the perimeter length of the cross section of each ridge 3a, 3b remained unrestrained along each ridge 3a, 3b slatting 34 from the border between the each ridge 3a, 3b and a gutter bottom 2 in the ends of portions to be formed into ridges 3a, 3b. (0091] In Example 2, a structural member I was manufactured using the ridge pad 5 15C illustrated in FIG. 10 by the manufacturing method according to the present embodiment. In Example 2, the ridge pad 15 restrained the region of the whole perimeter length of the cross section of each ridge 3a, 3b in the ends of portions to be formed into the ridges 3a, 3b. In addition to this, the end of the portion to be formed into a gutter bottom 2 was also restrained in Example 2. 10 (0092] In Comparative Example 1, as illustrated in FIG. 7 (a) and (b), a structural member was manufactured wltile restraining the whole pmiion to be formed into the gutter bottom 2 in .the forming material 16 and not restraining the ends of the potiions to be formed into the ridges 3a, 3b under the same conditions as in Example 15 1 except using the pad 15'. [0093] The fornting material 16 was a 1.4 mm thick steel sheet having a tensile strength of 980 MPa class, which was measured by tensile testing in accordance with JIS Z 2241. In addition, the structural member to be manufactured had a 20 substantially gutter"shap-ed ·cross section of 100 mm in height and 80mm in gutter bottom width and an outward continuous flange 7 of 15 mm in flange width. Shoulders of a punch used had a curvature radius of 12 mm. (0094] (1-1) Increase Rate of Sheet Thickness (Decrease Rate of Sheet Thickness) 25 Numerical analyses using the finite element method were performed on increase rates of sheet thickness (decrease rates of sheet thickness) in the vicinity of 35 the ridge flanges 7a, 7b of the structural members to be manufactured in Example I, 2 and Comparative Example I. The analyses showed that a maximum decrease rate of sheet thickness in the edge of the ridge flange in the structural member according to Comparative Example I was about 29.8%, and a maximum increase rate of sheet 5 thickness near the base of the ridge flange in the structural member according to Comparative Example 1 was about 17.0%. [0095] In contrast, maximum decrease rates of sheet thickness in the edges of the ridge flanges 7a, 7b of the structural members 1 according to Examples 1, 2 were 10 about 12.5% and about 13.4%, respectively. It was therefore shown that cracking in the edges of the ridge flanges 7a, 7b can be reduced more in the structural members 1 of Examples 1, 2 than in the structural member of Comparative Example 1. Maximum increase .. rates of sheet thickness near the base of the ridge flanges 7a, 7b ofthe structural members 1 according to Examples I, 2 were about 14.1% and about 15 13.0%, respectively. It was therefore shown that wrinkling near the base of each ridge flange 7a, 7b can be reduced more in the structural members I of Examples I, 2 than in the structural member of Comparative Example I. [0096] (1-2) A Pad Load 20 In manufacturing structural members according to Example 1 and Comparative Example I, the pad load required for the pad pressing and restraining the forming material 16 against the punch 13 was then obtained. The results showed that the pad load of the ridge pad 15 of Example 1 was approximately 1.2 times larger than that of Comparative Example I, and thus the ridge pad 15 of 25 Example 1 did not require a considerable increase in the pad load. [0097] 36 (1-3) Extent of Restraining Numerical analyses using the finite element method were then performed on the influence of a restraining extent in the pmiions to be formed into the ridges 3a, 3b on the increase rate of sheet thickness (decrease rate of sheet thickness) in the above- 5 mentioned method of manufacturing the structural member 1 of Example 1. The angle 0 of an unrestrained extent as illustrated in FIG. 6 (a) was changed within the range from oo to 45°, where the angle 0 = oo means that the whole end region of the pmiions to be formed into the ridges 3a, 3b is pressed. If the angle 0 = 45°, a 1/2 region of the perimeter of the cross section of each ridge 3a, 3b starting Jiom the 10 border between the pmiion to be formed into each ridge 3a, 3b and the portion to be formed into the gutter bottom 2 is left unrestrained. [0098] The .analyses showed that a maximum decrease rate of sheet thickness in the edges of the ridge flanges 7a, 7b when the angle 0 = 0° was about 13.1%. As the 15 angle 0 increased, in other words, as the restraining region decreased, the maximum decrease rate dropped, and when the angle 0 = 45°, a maximum decrease rate of sheet thickness in the edges of the ridge flanges 7a, 7b was 12.5%. When the angle 0 is in the range from 0° to 45°, the maximum decrease rates of sheet thickness in the edges of the ridge flanges 7a, 7b are within an acceptable level. 20 [0099] (1-4) Curvature Radius of Shoulder of Punch Numerical analyses using the finite element method were performed on the relationship between the decrease rate of sheet thickness in the edge of each ridge flange 7a, 7b to be formed and the curvature radius Rp of the shoulder 13bb of the 25 punch 13 of the press-forming apparatus (the first press-forming apparatus) 11 used in the first step in the methods for manufacturing the structural members according to 37 above-described Example I and Comparative Example I. Structural members were manufactured using a forming material of a 2.3 mm thick steel sheet having a tensile strength of 590 MPa class, which was measured by tensile testing in accordance with ZIS Z 2241, under the same conditions except changing the curvature radius Rp of 5 the shoulder 13bb of the punch 13. The curvature radius Rp of the shoulder 13bb of the punch 13 was changed within the range of 0 mm to 45 mm. [0100] The analyses results are shown in FIG. 14. The horizontal axis represents the curvature radius Rp (nm1) of the shoulder 13bb of the punch 13, and the vertical 10 axis represents the maximum value (relative value) of the decrease rate of sheet thickness. FIG. 14 shows that the maximum value of the decrease rate of sheet thickness drops in the range of the curvature radius Rp of the shoulder 13bb being 45 mm or less when using the ridge pad 15 according to Example 1, as compared to the case of using the pad according to Comparative Example I. In addition, in the case 15 of using the ridge pad 15 according to Example 1, breakage in the edges of the ridge flanges 7a, 7b occurred when the curvature radius Rp of the shoulder 13bb was less than 2mm, and a desired outward continuous flange 7 was unable to be obtained. [0101] It was therefore shown that, when using the ridge pad 15 according to 20 Example I, the strain produced in the ends of the ridge flanges 7a, 7b and the ridges 3a, 3b can be reduced while maintaining the formability of the press formed product, as compared with the case of using the pad according to Comparative Example I, if the curvature radius Rp of the shoulder 13bb of the punch 13 remains within the range fi·om 2 mm to 45 mm. 25 [0102] (2) Examples 3, 4 and Comparative Example 2 38 In Examples 3, 4 and in Comparative Example 2, structural members were manufactured using a forming material 16 of a 3.2 mm thick steel sheet having a tensile strength of 270 MPa class, which was measured by tensile testing in accordance with ZIS Z 2241, under the same conditions as in Examples 1, 2 and 5 Comparative Example 1. [0103] (2-1) Increase Rate of Sheet Thickness (Decrease Rate of Sheet Thickness) Numerical analyses using the finite element method were performed on increase rates of sheet thickness (decrease rates of sheet thickness) in the vicinity of 10 the ridge flanges 7a, 7b of the shuctural members to be manufactured according to Example 3, 4 and Comparative Example 2. The analyses showed that a maximum decrease rate of sheet thickness in the edges of the ridge flanges in the structural member according to Comparative Example 2 was about 12. 7%, and a maximum increase rate of sheet thickness near the bases of the ridge flanges in the structural 15 member according to Comparative Example 2 was about 6.8%. [0104] In contrast, maximum decrease rates of sheet thickness in the edges of the ridge flanges 7a, 7b of the structural members 1 according to Examples 3, 4 were about 7.5% and about 7.6%, respectively. It was therefore shown that cracking in 20 the edges of the ridge flanges 7a, 7b can be reduced more in the structural members 1 of Examples 3, 4 than in the structural member of Comparative Example 2. Maximum increase rates of sheet thickness near the bases of the ridge flanges 7a, 7b of the structural members 1 according to Examples 3, 4 were about 5.2% and about 6.5%, respectively. It was therefore shown that wrinkling near the base of the ridge 25 flanges 7a, 7b can be reduced more in the structural members 1 of Examples 3, 4 than in the structural member of Comparative Example 2. 39 [0 I 05] (2-2) Pad Load In manufacturing the structural members according to Example 3 and Comparative Example 2, the pad load required for the pad pressing and restraining 5 the forming material 16 against the punch 13 was then obtained. The results showed that the pad load of the ridge pad 15 of Example 3 was approximately 1.3 times larger than that of the pad of Comparative Example 2, and thus the pad of Example 3 did not require a considerable increase in the pad load. 10 [Reference Signs List] [0106] 1 structural member 2 gutter bottom 3a, 3b ridge 15 4a, 4b vertical wall Sa, 5b curved section 6a, 6b flange 7 outward continuous flange 7a, 7b ridge flange 20 11 press~forming apparatus (first press-forming apparatus) 13 punch 13ba upper surface 13bb shoulder 14 die 25 15, 15a, 15b, 15c pad (ridge pad) 15-1, 15-2 restraining part 5 16 forming material 20 jointed structure 21 pad (ridge pad) 21-1, 21-2 restraining part 21-3 recess [Name of Document] CLAIMS [Claim 1] A method for manufacturing a structural member for an automotive body, the structural member being formed by pressing a forming material made of a steel 5 sheet by using a press-forming apparatus having a punch, a die, and a pad facing the punch, the structural member extending in a predetermined direction, having a substantially gutter-shaped cross section intersecting the predetermined direction, and including 10 a gutter bottom, a ridge continuing to the gutter bottom, a vetiical wall continuing to the ridge, and an outward continuous flange being continuously formed along at least one end in the predetermined direction, the one end at least including a part of the ridge, a pati of the gutter bottom, and a part of the vertical wall, 15 the method comprising: a first step in which the pad presses the forming material against the punch to raise a pmiion corresponding to a flange to be formed in ends of at least the gutter bottom and the ridge in a direction opposite to the pressing direction, and 20 '•1he ·punch and the die carry out press forming to form an 25 intermediate product, while the pad bends an end of a portion to be formed into the ridge in the pressing direction and restrains at least a part of the end, and a region other than an end in a portion to be formed into the gutter bottom remains unrestrained; and a second step in which the intermediate product is further pressed to form the structural member for the automotive body. [Claim 2] 42 The method for manufacturing a structural member for an automotive body according to claim I, wherein at least a part of the end of the p01tion to be formed 5 into the gutter bottom is unrestrained in the first step. [Claim 3] The method for manufacturing a structural member for an automotive body according to claim 1 or 2, wherein the whole portion to be formed into the gutter bottom and at least a part of the portion corresponding to the flange to be formed in 10 the end of the gutter bottom, the part continuing to the pmtion to be formed into the gutter bottom, remain unrestrained in the first step. [Claim 4] The method for manufacturing a press formed product according to any one of claims 1 to 3, wherein a portion of at least 1/2 length of a perimeter of a cross 15 section in the end of the pmtion to be formed into the ridge, the 1/2 length slatting from a border between the pmtion to be formed into the ridge and the portion to be formed into the gutter bottom, remains unrestrained in the first step. [Claim 5] The method for manufacturing a stmctural member for an automotive body 20 according to any one of claims 1 to 4, wherein, the punch used in the first step has a shoulder having a surface for forming the ridge, and at least a pmtion of the shoulder corresponding to the end in the predetermined direction has a curvature radius ranging fi·om 2 nllll to 45 mm. [Claim 6] 25 The method for manufacturing a structural member for an automotive body according to any one of claims 1 to 5, wherein the steel sheet is a steel sheet of 2.3 43 mm or more in thickness or a high-tensile steel sheet of 440 MPa or more in tensile strength. [Claim 7] A press-forming apparatus used for manufacturing a structural member for an 5 automotive body, the structural member extending in a predetermined direction, having a substantially gutter-shaped cross section intersecting the predetermined direction, and including a gutter bottom, a ridge continuing to the gutter bottom, 10 a vertical wall continuing to the ridge, and an outward continuous flange being continuously formed along at least one end in the predetermined direction, the one end at least including a part of the ridge, a part of the gutter bottom, and a part of the vettical wall, the press-forming apparatus comprising: a punch; a die; and a pad facing the punch, 15 the punch and the die carrying out press forming while the pad and the punch restraining a forming material made of a steel sheet, wherein the pad presses the forming material to bend an end of a portion to be formed into the ridge in the pressing direction, and restrains at least a pmt of the end while a region other than atl end in a portion to be formed into the gutter bottom 20 remains unrestrained. [Claim 8] The press-forming apparatus according to claim 7, wherein the pad leaves at least a part of the end of the portion to be formed into the gutter bottom unrestrained. [Claim 9] 25 The press-forming apparatus according to claim 7 or 8, wherein the pad leaves unrestrained the whole portion to be formed into the gutter bottom and at least 44 a part of the po1tion corresponding to the flange to be formed in the end of the gutter bottom, the part continuing to the portion to be formed into the gutter bottom. [Claim 1 0] The press-forming apparatus according to any one of claims 7 to 9, wherein 5 . the pad leaves unrestrained a portion of at least 112 length of a perimeter of a cross · section in the end of the pmtion to be formed into the ridge, the 112 length starting from a border between the portion to be formed into the ridge and the pmtion to be formed into the gutter bottom. [Claim 11] 10 The press-forming apparatus according to any one of claims 7 to 10, wherein the punch has a shoulder having a surface for forming the ridge, and at least a pmtion of the shoulder conesponding to the end in the predetermined direction has a curvature radius ranging from 2 mm to 45 mm.