PRESS FORMING METHOD AND PRESS FORMING APPARATUS FOR AUTOMOBILE EXTERIOR PANEL.

Abstract

A press-forming method for an exterior panel of an automobile, according to the present invention, is a method of press-forming a metal sheet (101) into an exterior panel (111) of an automobile, the exterior panel (111) having a character line (113), a panel surface portion (115), and a panel surface portion (117), and the press-forming method includes: a step of moving the die (5) relative to the punch (3) and bringing into contact a lateral punch spring body (9) and a lateral die spring body (11) with the metal sheet (101), the lateral punch spring body (9) being provided to protrude from a lateral punch forming surface portion (3c) that is to form the panel surface portion (117),the lateral elastic body of the die (11) being provided to protrude from a portion of the lateral forming die surface (5b) that is to form the panel surface portion (115); and a step of obtaining the exterior panel (111) of the automobile by pressure forming while compressing the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) by moving the die (5) relative to the punch (3) until a bottom dead center is reached, the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) still being in contact with the sheet metal (101).

Description

PRESS FORMING METHOD AND PRESS FORMING APPARATUS FOR AUTOMOBILE EXTERIOR PANEL FIELD The present invention relates to press forming methods and press forming apparatus for automotive exterior panels, the press forming methods and press forming apparatus being for forming metal sheets into automotive exterior panels by press forming the exterior panels, the exterior panels having character lines formed therein. With respect to the present invention, a metal sheet refers to a sheet formed from any of various metals, such as stainless steel, aluminum, and magnesium, for example, a hot-rolled steel sheet, a cold-rolled steel sheet, or a surface-treated steel sheet, which is a steel sheet that has undergone surface treatment (such as electroplating, hot-dip galvanizing, or organic coating treatment). BACKGROUND The exterior panels of automobiles, such as the exterior of doors, front bumpers, or rear bumpers, often have character lines formed on their outer surfaces to improve design capabilities and tensile rigidity. These character lines are typically formed by pressing a sheet of metal (the blank) against a ridge line provided on a punch and clamping the sheet between the ridge line and a valley line of the die. In recent years, in particular, to further enhance automotive design, there has been a demand for character lines that are sharp (i.e., have a high curvature [small radius of curvature] of the ridge lines). In this type of press forming, a linear pattern can be generated by contact between a ridge line of a punch and a distinct portion of a part where a character line is supposed to be formed. This linear pattern will remain after coating and will become an appearance defect called a slip line defect on the outer panel. Such slip line defects act as a constraint on improving automotive designability because a slip line defect becomes particularly noticeable when press forming is performed using a punch with a ridge line whose distal end is formed by a small circular arc with a small cross-sectional radius in an attempt to create a sharp character line. So far, several techniques have been proposed to form character lines while minimizing the generation of such linear patterns. e / cfrnn / eznz / e / Yi For example, in a method disclosed in Patent Literature 1, an auxiliary cross-sectional shape for forming a design recess portion is provided in a die and blank holder, the periphery of a blank is held between them, a central portion of the blank is pre-bent deformed along a forming surface of a punch, and then the blank is formed by using a punch and a design surface is formed thereon.In a method disclosed in Patent Literature 2, a suction port is formed on a press surface in which a convex linear portion is provided to form a character line; press forming is performed by adhering a metal sheet to the press surface by using a suction device that implements suction through a gas flow path from the suction port, thereby minimizing movement of the metal sheet and avoiding slip lines.In a technique disclosed in Patent Literature 3, a steel sheet is subjected to primary forming by means of a punch angle and a cushioning pad, deep drawing and stretch forming are then performed while the punch is lowered, thus preventing the formation of a slip line in a portion of a metal sheet, the portion that has come into contact with the punch angle. In a technique disclosed in Patent Literature 4, in the manufacture of a press-formed part having a ridge line, slip lines are avoided and a high-quality press-formed part is obtained through a first press-forming process to create a preform shape and a second press-forming process to further shape the preform shape. In a technique disclosed in Patent Literature 5, an elastic body is provided in a distal end portion of a punch, minimizing the tendency to bend due to initial contact by the punch, minimizing the displacement of any bending tendency generated from a character line, and thus minimizing slip lines when forming the character line.In a technique disclosed in Patent Literature 6, a character line is formed on a blank by a die pad consisting of an elastic body and a distal end portion of a punch, and a separate portion of the character line is formed by a die and punch, the formed character line still being constrained by the die pad and punch. In a technique disclosed in Patent Literature 7, a plate-shaped workpiece is pressed against a lower die having a convex R portion to form a character line. The workpiece is brought into contact with a pressing pad, in a position close to the convex R portion, after the workpiece has clamped the convex R portion, thereby minimizing slippage of the workpiece. QUOTE LIST e / cfrnn / eznz / e / Yi Patent Literature Patent Literature 1: Japanese Patent No. 5845623 Patent Literature 2: Publication of Unexamined Japanese Patent Application No. 2003-260611 Patent Literature 3: Publication of Examined Japanese Patent Application No. 57-2252. Patent Literature 4: Japanese Patent No. 5845623 Patent-Related Literature 5: Publication of Unexamined Japanese Patent Application No. 2003-260611 Patent Literature 6: Publication of Unexamined Japanese Patent Application No. 2003-260611 Patent Literature 7: Publication of Unexamined Japanese Patent Application No. 2003-260611 e / cfrnn / eznz / e / Yi BRIEF DESCRIPTION Technical Problem However, the techniques disclosed in Patent Literature 1 to Patent Literature 7 have the following problems. In the technique disclosed in Patent Literature 1, the deformation by the die and the blank holder provided with the auxiliary forming cross-section is not restricted by the punch; only the two extreme portions of the blank corresponding to the design recess portion are able to be restricted, and the bending deformation is thus limited to straight line shapes. The technique disclosed in Patent Literature 2 has problems in that it requires a suction device that is not used in normal press forming, and the shape of the suction nozzle is transferred to a surface of the formed part. The technique disclosed in Patent Literature 3 has problems in that the shape of the final product is only partially formed during the forming process, and surface deviation occurs at the boundary of the incompletely formed portion. The technique disclosed in Patent Literature 4 has problems in that the die for forming the preform shape is different from the die for forming the target shape, and the number of processes, including the die-changing process, increases. The technique disclosed in Patent Literature 5 has problems in that a shape identical to the ridge line shape cannot be formed because the convex side of the ridge line is formed by the elastic body. The technique disclosed in Patent Literature 6 has problems in that, in a case where multiple character lines are close to one another, the character lines cannot be formed identical to the desired shape because the character lines are formed by a die pad made of an elastic body.The technique disclosed in Patent Literature 7 has problems in that in a case where the shape of a surface is complex, the appropriate time to put a pressing pad in contact with a workpiece cannot be established and a defect is generated in the workpiece by the pressing pad. The present invention has been made in view of the problems described above, and an objective of the present invention is to provide a press forming method and a press forming apparatus for exterior automotive panels, the press forming method and the press forming apparatus enabling: the prevention of slip lines without increasing man-hours for press forming; and the formation of objective lines. Solution to the Problem To solve the problem and achieve the objective, a press forming method for an exterior panel of an automobile according to the present invention is the press forming method for press forming a sheet metal into the exterior panel of the automobile, the exterior panel having a character line and a panel surface portion that is continuous on both sides of the character line, by using a punch, a die oriented towards the punch, and a blank holder oriented towards extreme portions of the die, wherein the punch includes: a ridge line for forming the character line; a side forming surface portion of the punch for forming the panel surface portion;and a lateral elastic body of the punch supported to project into the die than the lateral forming surface portion of the punch, so that the lateral elastic body of the punch can come into contact with the sheet metal, along a portion equivalent to the character line corresponding to the character line on the sheet metal, in a position away from the portion equivalent to the character line, on a longer side under tension in the press forming between portions on both sides interposing the portion equivalent to the character line and the die includes: a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the panel surface portion;and a lateral elastic die supported to project towards the punch that the lateral die forms the surface portion so that the lateral elastic body of the die comes into contact with the sheet metal and presses it, along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a side of lesser stress in the press that forms between portions on both sides that interpose the portion equivalent to the character line. The press forming method includes: a contact step with the elastic body of moving the die relatively towards the punch in a state in which both end portions of the sheet metal are interposed between the die and the blank holder, and bringing each of the lateral elastic bodies of the punch and the lateral die into contact with the sheet metal;and a press forming the pressing step that forms the sheet metal into the exterior automotive panel, the exterior panel having the character line formed by means of the ridge line and the valley line, moving the die relatively towards the punch to a bottom dead center with the punch side spring body and the die side spring body both being in contact with the sheet metal, wherein an amount of protrusion of the punch side spring body from the punch side forming surface portion is established so that the punch side spring body: comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal at the spring body contact step;and is flush with the side forming surface portion of the punch at the bottom dead center, and a quantity of lateral die spring body projection is established from the side forming surface portion of the die such that: the lateral die spring body comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal and the sheet metal is plastically deformed at the spring body contact step; and a frictional force given by a product of: a load from the lateral die spring body pressing the sheet metal at the press forming step; and a coefficient of friction between the lateral die spring body and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line. Furthermore, a press-forming method for an exterior panel of an automobile according to the present invention is the press-forming method for press-forming a sheet metal into the exterior panel of an automobile, the exterior panel having a character line and a panel surface portion that is on both sides of the character line and continuous, by using a punch, a punch-oriented die, and a blank holder oriented towards extreme portions of the die, wherein the punch includes: a ridge line for forming the character line; a side-forming surface portion of the punch for forming the panel surface portion;and a lateral elastic punch body supported to project into the die than the lateral forming surface portion of the punch, so that the lateral elastic punch body can come into contact with the sheet metal along a portion equivalent to the character line corresponding to the character line on the sheet metal, with a portion of the sheet metal portions being in a position away from the portion equivalent to the character line on a lesser side under tension in the press forming between portions on both sides interposing the portion equivalent to the character line, and the die includes a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the panel surface portion;and a lateral elastic body of the die supported to project towards the punch than the lateral forming surface portion of the die, so that the lateral elastic body of the die comes into contact with and presses the sheet metal, along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a greater side in tension in the press forming between portions on both sides that interpose the portion equivalent to the character line, comprising. The press forming method includes: a contact step with the elastic body of moving the die relatively towards the punch in a state in which both ends of the sheet metal are interposed between the die and the blank holder, and bringing the lateral elastic body of the punch and the lateral elastic body of the die into contact with the sheet metal;and a pressing forming step of shaping the sheet metal into the exterior automotive panel, the exterior panel having the character line formed by means of the ridge line and the valley line, moving the die relatively towards the punch to a bottom dead center with the lateral spring body of the punch and the lateral spring body of the die both being in contact with the sheet metal, wherein an amount of projection of the lateral spring body of the punch from the lateral forming surface portion of the punch is established so that the lateral spring body of the punch: comes into contact with the sheet metal before the ridge line of the punch comes into contact with the sheet metal;and is flush with the side forming surface portion of the punch at the bottom dead center, and a quantity of lateral die spring body projection from the side forming surface portion of the die is established so that: the lateral die spring body comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal and the sheet metal is plastically deformed at the spring body contact step; and a frictional force given by a product of: a load from the lateral die spring body pressing the sheet metal at the press forming step; and a coefficient of friction between the lateral die spring body and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line. Furthermore, in the press forming method for the exterior automotive panel according to the present invention, the lateral elastic punch body is movable along a press forming direction and is provided in the punch by means of a movable lateral punch body that supports the lateral elastic punch body by pressing the lateral elastic punch body towards the die. Furthermore, in the press forming method for the exterior automotive panel according to the present invention, the lateral die elastic body is movable along a press forming direction and is provided in the die by a movable lateral die body that supports the lateral die elastic body by pressing the lateral die elastic body towards the punch. Furthermore, a press forming apparatus for an exterior panel of an automobile according to the present invention is a press forming apparatus for the press forming of a sheet metal in the exterior panel of the automobile, the exterior panel having a character line and a continuous panel surface portion on both sides of the character line. The press forming apparatus comprises: a punch; a die oriented towards the punch; and a blank holder oriented towards the end portions of the die, wherein the punch includes: a ridge line for forming the character line; a side forming surface portion of the punch for forming the panel surface portion;and a lateral elastic punch body supported to project into the die more than the lateral forming surface portion of the punch, so that the lateral elastic punch body e / cfrnn / eznz / e / Yi can come into contact with the sheet metal, along a portion equivalent to the character line corresponding to the character line on the sheet metal, in a position away from the portion equivalent to the character line, on a side of greater tension in the forming press between portions on both sides that interpose the portion equivalent to the character line, and being greater in tension in the forming press, the portions of the sheet metal on both sides interposing the portion equivalent to the character line, and the die includes: a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the panel surface portion;and a lateral elastic body of the die supported to project towards the punch that the side of the die forming the surface portion so that the lateral elastic body of the die comes into contact with and presses the sheet metal, along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a side of lesser stress in the pressing formed between portions on both sides that interpose the portion equivalent to the character line, wherein the amount of projection of the lateral elastic body of the punch from the lateral forming surface portion of the punch is set so that the lateral elastic body of the punch: comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal when the die is moved relative to the punch;and is flush with the side forming surface portion of the punch at a bottom dead center, and the amount of projection of the side spring body of the die from the side forming surface portion of the die is established so that: the side spring body of the die comes into contact with the sheet metal before the ridge line of the punch comes into contact with the sheet metal and the sheet metal is plastically deformed when the die moves relative to the punch; and a frictional force given by a product of: a load of the side spring body of the die pressing on the sheet metal; and a coefficient of friction between the side spring body of the die and the sheet metal, becomes equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the equivalent portion of the character line. Furthermore, a press forming apparatus for an exterior panel of an automobile according to the present invention is a press forming apparatus for the press forming of a sheet metal in the exterior panel of the automobile, the exterior panel having a character line and a continuous panel surface portion on both sides of the character line. The press forming apparatus includes: a punch; a die oriented to the punch; and a blank holder oriented to the end portions of the die, wherein the punch includes: a ridge line for forming the character line; a lateral forming surface portion of the punch that forms the surface portion of the panel; and a laterally supported punch body projecting toward the die that supports the lateral forming surface portion of the punch.so that the lateral elastic body of the punch can come into contact with the sheet metal, along a portion equivalent to the character line on the sheet metal corresponding to the character line on the sheet metal, with a portion of the sheet metal portions being in a position away from the portion equivalent to the character line, on one side and being less in tension in the pressure forming, the portions of the sheet metal being on both sides interposing the portion equivalent to the character line, and the die includes: a valley line to form the character line in cooperation with the ridge line; a side forming die surface portion to form the panel surface portion; and a lateral elastic body of the die supported to project towards the punch more than the side forming die surface portion,so that the lateral elastic body of the punch comes into contact with and is able to press, along the portion equivalent to the character line in the sheet metal, a portion of the sheet metal portions, the portion being in a position away from the portion equivalent to the character line and being greater in tension in the forming by pressing, the sheet metal portions being on both sides interposing the portion equivalent to the character line, wherein a protrusion of the lateral elastic body of the punch from the lateral forming surface portion of the punch is established so that the lateral elastic body of the punch: comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal when the die moves relative to the punch; and is flush with the lateral forming surface portion of the punch at a bottom dead center,and a quantity of protrusion of the lateral die body from the lateral forming surface portion of the die is established such that: the lateral die body comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal and the sheet metal is plastically deformed when the die moves relative to the punch; and a frictional force, given by the product of: a load on the lateral die body pressing on the sheet metal; and a coefficient of friction between the lateral die body and the sheet metal, is made equal to or greater than an absolute value of the difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line. Furthermore, in the press forming apparatus for the exterior automotive panel according to the present invention, the lateral elastic punch body is movable along a press forming direction and is provided in the punch by means of a movable lateral punch body that supports the lateral elastic punch body by pressing the lateral elastic punch body towards the die. Furthermore, in the press forming apparatus for the exterior automotive panel according to the present invention, the lateral elastic die body is movable along a press forming direction and is provided in the die by means of a movable lateral die body that supports the lateral elastic die body by pressing the lateral elastic die body towards the punch. e / cfrnn / eznz / e / Yi Advantageous Effects of the Invention The present invention allows: preventing the generation of a bending defect in a sheet metal due to a punch ridge line, by placing a lateral elastic punch body protruding from a portion of the lateral forming surface of the punch, in contact with the sheet metal, to support the sheet metal, in a position away from a portion equivalent to the character line, in the process of pressing the sheet metal into an exterior panel of an automobile by using the punch having the ridge line, a punch-oriented die having a valley line, and a blank holder oriented towards the end portions of the die, the exterior panel having a character line and a panel surface portion being on both sides of the character line, the character line being formed by the ridge line and the valley line;Preventing slippage of the metal sheet due to a tension difference acting on both sides of the portion equivalent to the character line of the metal sheet, by bringing into contact with the metal sheet a lateral elastic die body that protrudes from a portion of the lateral forming surface of the die, to press the metal sheet in a position opposite to the lateral elastic punch body and away from the portion equivalent to the character line, and, in this way, making a frictional force greater than the tension difference, the frictional force being between the metal sheet and the lateral elastic die body that protrudes from the portion of the lateral forming surface of the die and that is compressed; and, in this way, obtaining the exterior panel of an automobile by forming by pressing, the exterior panel having the character line formed therein, reducing the slip lines.; BRIEF DESCRIPTION OF THE DRAWINGS Figures 1(a) to 1(e) are a diagram illustrating a press forming method and a press forming apparatus configuration for exterior automotive panels, in accordance with a first embodiment of the present invention. Figure 2 is a diagram illustrating a load P for pressing a metal sheet by means of a lateral elastic die body that has been compressed and the tension Fi and the tension F2 generated in the metal sheet, in the press forming process by means of the press forming method and the press forming apparatus for exterior automotive panels, in accordance with the first embodiment of the present invention. Figures 3(a) to 3(e) are a diagram illustrating a press forming method and a press forming apparatus configuration for exterior automotive panels, in accordance with another embodiment of the first embodiment of the present invention. Figures 4(a) to 4(e) are a diagram illustrating a press forming method and a press forming apparatus configuration for exterior automotive panels, in accordance with a second embodiment of the present invention. Figures 5(a) to 5(e) are a diagram illustrating a press forming method and a configuration of a press forming apparatus for exterior automotive panels, in accordance with another mode of the second embodiment of the present invention. Figure 6 is a diagram illustrating an exterior panel to be formed in the Examples, and the arrangement when evaluating the shape and any slip lines on a portion of the exterior panel surface. Figure 7 is a diagram illustrating the results of the cross-sectional shapes of the exterior panels, obtained by press forming analysis, in the Examples. Figure 8 is a diagram that illustrates the results of the evaluation of As values ​​for the surface deformation of the exterior panels, results obtained through the press forming analyses, in the Examples. Figures 9(a) to 9(d) are a diagram illustrating the operation of a conventional press forming method and a conventional press forming apparatus for automotive exterior panels, and a slip line generated in the press forming process. DESCRIPTION OF THE MODALITIES A slip line generated in the press forming of an exterior panel of an automobile, the exterior panel having a character line, will be described before the description of the press forming methods and press forming apparatus for exterior panels of automobiles, in accordance with a first embodiment and a second embodiment of the present invention. Why are landslides generated? An exterior panel (111) of an automobile, the exterior panel (111) being the object of the present invention, has, for example, as illustrated in Figure 9(d), a character line (113) and a panel surface portion (115) and a panel surface portion (117) that are on both sides of the character line and are continuous (113), and is obtained by deep drawing as follows by using a press-forming apparatus (51) that includes a punch (53) having a ridge line (53a) extending in a direction perpendicular to the paper plane of Figure 9(d), a die (55) having a valley line (55a) extending in the direction perpendicular to the paper plane, and a blank holder (57) facing both end portions of the die (55). First, as illustrated in Figure 9(a), each of an end portion (101a) and an end portion (101b) of a metal sheet (101) is inserted between the die (55) and the blank holder (57). With the metal sheet (101) still inserted, as illustrated in Figure 9(a) to Figure 9(d), the die (55) and the blank holder (57) are moved relative to the punch (53) to a bottom dead center, and the outer panel (111) of an automobile is obtained by forming by pressing, the outer panel (111) having the character line (113) formed thereon by means of the ridge line (53a) of the punch (53) and the valley line (55a) of the die (55). In the pressing process, the relative movement of the die (55) toward the punch (53) first causes the ridge line (53a) of the punch (53) to come into contact with the sheet metal (101), inducing an initial bend in the sheet metal (101) (Figure 9(b)). In the deep drawing process using the die (55) and the punch (53), tension is generated in the sheet metal (101) (Figure 9(b) and Figure 9(c)) in directions toward the end portion (101a) and the end portion (101b) from the initial defective bend between them. The magnitudes of the stress generated on either side of the initial bending defect in the metal sheet (101) differ from each other depending on: the distances from the initial bending defect to the end portion (101a) and the end portion (101b) and the angles of the panel surface portion (115) and the panel surface portion (117) (Figure 9(d)) with respect to a press forming direction; or a difference between, for example, the forming depths from the crest line (53a) to the end portion (101a) and the end portion (101b), the depths depending on the forming direction on such distances and angles. For example, in a case where an acute angle of the panel surface portion (115) with reference to a line drawn in the press-forming direction from the crest line (53a) of the punch (53) is (0a), an acute angle of the panel surface portion (117) with respect to the line is (0b), and the angle (0b) of the panel surface portion (117) is less than the angle (0a) of the panel surface portion (115) (see Figure 9(d)), the stress generated toward the end portion (101b) (a portion (107)) of the sheet metal (101) becomes greater than the stress generated toward the end portion (101a) (a portion (105)) of the sheet metal (101) in the press-forming process (Figure 9(b) and Figure 9(c)). In response to the generation of a tension difference between these portions on either side of the initial bending defect, a slip occurs toward the portion of higher tension in the sheet metal (101), and the initial bending defect shifts toward the end portion (101b) of higher tension (Figure 9(c)). Subsequently, the initial bending defect is flattened by the punch (53) and die (55) at the bottom dead center, and a linear pattern, i.e., a slip line, is generated (Figure 9(d)). As described above, a slip line on the outer panel (111) of an automobile, the outer panel (111) having the character line (113) formed thereon, is caused by unbalanced stress generated in the sheet metal (101) during the deep drawing process. Examples of causes of unbalanced stress include, as already described, a difference between the forming depths of the end portion (101a) and the end portion (101b) of the sheet metal (101), the difference being due to differences in distances and angles from the portion where the ridge line (53a) of the punch (53) makes contact with the end portion (101a) and the end portion (101b) of the sheet metal (101). That is, in a case where the end portion (101 a) and the end portion (101 b) of the metal sheet (101) have different forming depths, the stress generated towards the end portion (101b) with greater forming depth becomes greater, and due to the difference in stress with respect to that generated towards the end portion (101a) with less forming depth, the metal sheet (101) slides towards the end portion (101b) and a slip line is generated. The methods of press forming and the press forming apparatus for exterior automotive panels, according to the first and second embodiments of the present invention, will be described below. The same reference symbol will be assigned to components having the same or corresponding functions, and redundant descriptions of these components will be avoided in the following description. First Modality Press Forming Machines For example, as illustrated in Figures 1(a) to 1(e), a press forming apparatus (1) for exterior automotive panels (hereafter simply referred to as press forming apparatus (1)), according to the first embodiment, is for press forming a metal sheet (101) into an exterior automotive panel, the exterior panel having a character line (113) and a panel surface portion (115) and a panel surface portion (117) that are on both sides of the character line and are continuous (113), and the press forming apparatus (1) includes a punch (3), a die (5), a blank holder (7), a punch side spring body (9), and a die side spring body (11). Figure 1(a) is a state before forming begins, Figure 1(b) is a state where the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) are in contact with the metal sheet (101), Figure 1(c) is a state where the metal sheet (101) is being supported by the lateral elastic body of the punch (9), Figure 1(d) is a state where the metal sheet (101) is being pressed by the lateral elastic body of the die (11), and Figure 1(e) is a state at bottom dead center. Furthermore, for an exterior panel (111) of an automobile ((Figure 1(e)), the exterior panel (111) being a target to be formed in this first mode, as illustrated in Figures 9(a) to 9(d) already described, it is assumed that the tension generated towards an end portion (101b) from a boundary that is a portion equivalent to a character line (103) in the metal sheet (101) is greater than the tension generated towards an end portion (101a) from the boundary, in the press forming process (see Figure 2). Awl The punch (3) has, as illustrated in Figures 1(a) to 1(e): a ridge line (3a); a punch side forming surface portion (3b) and a punch side forming surface portion (3c) that are positioned on both sides of the ridge line (3a) with the ridge line (3a) interposed between them; and a groove (3d). The ridge line (3a) will form the character line (113) (Figure 1(e)). The punched side forming surface portion (3b) and the punched side forming surface portion (3c) respectively form the panel surface portion (115) and the panel surface portion (117) (Figure 1(e)). The punched side forming surface portion (3b) is for forming a smaller portion (105) under tension acting on the metal sheet (101) in the panel surface portion (115) (Figure 1(e)) during the press forming process. On the other hand, the punched side forming surface portion (3c) is for forming a larger portion (107) under tension acting on the metal sheet (101) in the panel surface portion (117) (Figure 1(e)) during the press forming process. The groove (3d) has been formed to be concave in the lateral punch forming surface portion (3c) and has the lateral elastic punch body (9) provided therein. Die The die (5) has, as illustrated in Figures 1(a) to 1(e): a valley line (5a); a die-side forming surface portion (5b) and a die-side forming surface portion (5c) that are continuous on both sides of the valley line (5a) with the valley line (5a) interposed between them and are continuous; and a groove (5d). The valley line (5a) forms the character line (113), in cooperation with the edge line (3a) of the punch (3). The die-forming side surface portion (5b) shall form, in cooperation with the punch-forming side surface portion (3b), the panel surface portion (115), and the die-forming side surface portion (5c) shall form, in cooperation with the punch-forming side surface portion (3c), the panel surface portion (117). The die-forming side surface portion (5b) is for forming the smaller tension portion (105) acting on the metal sheet (101) in the panel surface portion (115) during the press forming process. On the other hand, the die-forming side surface portion (5c) is for forming the larger tension portion (107) acting on the metal sheet (101) in the panel surface portion (117) during the press forming process. The groove (5d) has been formed to be concave in the lateral die forming surface portion (5b) and has the lateral die elastic body (11) provided therein. Raw Parts Support As illustrated in Figures 1(a) to 1(e), the blank holder (7) is arranged to face both end portions of the die (5), and interposes, in cooperation with the die (5), the end portion (101a) and the end portion (101b) of the sheet metal (101) between them. e / cfrnn / eznz / e / Yi Lateral Elastic Body of the Punch As illustrated in Figure 1(a) 1(e), the lateral elastic punch body (9) has a lateral punch contact surface portion (9a) that comes into contact with the sheet metal (101), and the lateral punch contact surface portion (9a) is provided in the groove (3d) so that the lateral elastic punch body (9) protrudes: towards the die (5) more than the lateral punch forming surface portion (3c); and therefore is able to come into contact with the metal sheet (101), along the portion equivalent to the character line (103) corresponding to the character line (113) on the metal sheet, in the portion (107) of a larger side under tension in the pressing forming process between the portion (105) and the portion (107) of both sides that interpose the portion equivalent to the character line (103), in a position away from the portion equivalent to the character line (103). The lateral elastic body of the punch (9) protrudes from the lateral forming surface portion of the punch (3c) by an amount that has been established so that in the relative movement of the die (5) towards the punch (3), the lateral contact surface portion of the punch (9a) of the lateral elastic body of the punch (9) comes into contact with the metal sheet (101) before the ridge line (3a) of the punch (3) comes into contact with the metal sheet (101). The lateral elastic body of the punch (9) preferably has a hardness and shape that moderates the bending shape of the sheet metal (101), the bending shape being made by the ridge line (3a), in a state in which the lateral elastic body of the punch (9) protrudes from the lateral forming surface portion of the punch (3c) and is in contact with the sheet metal (101) to support the sheet metal (101), until the bottom dead center is reached; and allowing the lateral elastic body of the punch (9) to deform along the shape of the pressing die (the shape of the lateral forming surface portion of the punch (3c)) at the bottom dead center (Figure 1(e)), i.e., to deform (to contract in a pressing-forming direction) until the lateral contact surface portion of the punch (9a) is flush with the lateral forming surface portion of the punch (3c).A specific material for this lateral elastic punch body (9) can be, for example, a rubber or urethane material, with a Shore hardness of 40 to 100 HS. lateral elastic die body The lateral elastic body of the die (11): is provided to project further towards the punch (3) than the lateral forming surface portion of the die (5b), so that the lateral elastic body of the die (11) comes into contact with and presses the metal sheet (101) in portion 105, along the portion equivalent to the character line (103), with portion (105) in a position away from the portion equivalent to the character line (103), portion (105) being on a less stress-in-the-press forming side between portion (105) and portion (107) on either side of the portion equivalent to the character line (103) of the metal sheet (101); and has a lateral contact surface portion of the die (11a) that comes into contact with the metal sheet (101). e / cfrnn / eznz / e / Yi The lateral elastic body of the die (11) protrudes from the lateral forming surface portion of the die (5b) by an amount that has been established so that in the relative movement of the die (5) towards the punch (3), the lateral contact surface portion of the die (11a) comes into contact with the metal sheet (101), before the ridge line (3a) of the punch (3) comes into contact with the metal sheet (101) and the metal sheet (101) is plastically deformed.This amount of protrusion has been fixed so that the frictional force between the lateral elastic body of the die (11) and the metal sheet (101) is equal to or greater than an absolute value of a tension difference acting on the portion (105) and the portion (107) on both sides that interposes the portion equivalent to the character line (103), the frictional force being given by the product of: the load by which the portion (105) of the metal sheet (101) is pressed by contraction of the lateral elastic body of the die (11) compressed in the press forming process; and the coefficient of friction between the lateral elastic body of the die (11) (portion of lateral contact surface of the die (11a)) and the metal sheet (101). It can be determined that the plastic deformation of the metal sheet (101) by the crest line (3a) is caused, for example, when the deformation in a portion of the metal sheet (101) exceeds a deformation εO calculated by Equation (1) below, being the portion where the crest line (3a) has come into contact. ε0= t / 2R (1) In this case, R is the radius of curvature of the character line (113) and t is the thickness of the metal sheet (101). Furthermore, the frictional force between the elastic body of the die side (11) and the metal sheet (101) is adjusted to satisfy the following Equation (2). |Fi - F2| < P x μθ (2) In this case, as illustrated in Figure 2, Fi and F2 are the tension acting respectively on the portion (105) and the portion (107) on both sides that interpose the portion equivalent to the character line (103), P is the load (Figure 2) by which the metal sheet (101) is pressed due to the contraction of the lateral elastic body of the die (11), and μθ is the coefficient of friction between the lateral elastic body of the die (11) and the metal sheet (101). The load P can be calculated from the amount of contraction after compression until the lateral contact surface portion of the die (11a) is flush with the lateral forming surface portion of the die (5b), assuming that the amount of contraction of the lateral elastic body of the die (11) is equal to the amount of overhang of the lateral elastic body of the die (11) from the lateral forming surface portion of the die (5b). The coefficient of frictionμ6 can be measured beforehand by means of a slip test, for example. Or, in a case where a rubber or urethane material is used as the lateral elastic die body (11), as described below, the coefficient of friction μθ is generally e / cfrnn / eznz / e / Yi equal to 0.1 to 0.3 (lubricated) or pe® 0.5 to 0.6 (dry), so any of these values ​​can be used. The difference in tension (Fi - F2 in Equation (2)) acting on portion (105) and portion (107) on either side of the portion equivalent to the character line (103) in the press forming process can be determined beforehand by: an experiment in which the tension acting on the metal sheet (101) is actually measured using, for example, an extensometer in the press forming process to obtain the outer panel (111) of an automobile; or a press forming analysis for the outer panel (111) of an automobileby, for example, a finite element method (FEM). Preferably, the die-side spring body (11) has a hardness and shape that allow it to deform along the shape of the pressing die (the shape of the die-side forming surface portion (5b)) at the bottom dead center, i.e., to deform (contract in the pressing direction) until the die-side contact surface portion (11a) is flush with the die-side forming surface portion (5b). A specific material for this die-side spring body (11) can be, for example, a rubber or urethane material having a Shore hardness of 40 to 100 HS. Press Forming Method The press forming method for an exterior panel of an automobile, in accordance with the first modality, is, as illustrated in Figures 1(a) to 1(e), to form byThe metal sheet (101) is pressed into the outer panel (111) of an automobile using the press-forming apparatus (1) comprising the punch (3), die (5), blank holder (7), punch side spring body (9), and die side spring body (11), the outer panel (111) having the character line (113) and the panel surface portion (115) and panel surface portion (117) being on either side of the character line and continuous, (113), and the press-forming method comprising a spring body contact step and a press-forming step. The punch side spring body (9) is provided in the groove (3d) such that the punch side spring body (9) projects into the die (5) more than the punch side forming surface portion (3c); and thus be able to come into contact with the metal foil (101), along the portion equivalent to the character line (103),In the larger portion (107) under tension during the press forming process, in a position away from the portion equivalent to the character line (103), the portion (107) is on a larger side under tension during the press forming process between the portion (105) and the portion (107) on both sides, interposing the portion equivalent to the character line (103) of the metal sheet (101). As already described, the lateral die spring body (11) is provided in the groove (5d) so that the lateral die spring body (11) protrudes into the punch (3) more than the lateral die forming surface portion (5b); and thus come into contact with and press the metal sheet e / cfrnn / eznz / e / Yi (101) in portion (105), along the portion equivalent to the character line (103), with portion (105) in order to press portion (105), in a position away from the portion equivalent to the character line (103), the portion being(105) which is on a smaller side under tension in the press forming process between portion (105) and portion (107) on both sides, interposing the portion equivalent to the character line (103) of the metal sheet (101). Each of the contact steps with the elastic body and the press forming step will be described later. Elastic Body Contact Step The elastic body contact step is, as illustrated in Figure 1(a) to Figure 1(b), a relative movement step of the die (5) towards the punch (3) in a state in which the end portion (101a) and the end portion (101b) of the sheet metal (101) are being sandwiched between the die (5) and the blank holder (7), and bringing into contact each of the lateral contact surface portion of the punch (9a) of the lateral elastic body of the punch (9) and the lateral contact surface portion of the die (11a) of the lateral elastic body ofThe die (11) with the metal sheet (101). The lateral elastic body of the punch (9) projects from the lateral forming surface portion of the punch (3c) by an amount that has been established such that: the lateral contact surface portion of the punch (9a) comes into contact with the metal sheet (101) before the ridge line (3a) of the punch (3) comes into contact with the metal sheet (101); and the lateral contact surface portion of the punch (9a) is flush with the lateral forming surface portion of the punch (3c) at bottom dead center. The lateral elastic body of the die (11) projects from the lateral forming surface portion of the die (5b) by an amount that has been established such that: the lateral contact surface portion of the die (11a) comes into contact with the metal sheet (101) before a portion of the metal sheet (101) is plastically deformed, the portion being where the ridge line(3a) of the punch (3) comes into contact; and the lateral contact surface portion of the die (11a) is flush with the lateral forming surface portion of the die (5b) at the bottom dead center. The plastic deformation of the sheet metal (101) along the crest line (3a) can be determined, for example, by the strain εθ found using the aforementioned Equation (1). Likewise, the amount of overhang of the lateral elastic body of the die (11) is set, as expressed in the aforementioned Equation (2), such that the frictional force is equal to or greater than the absolute value |F1 - F2| of the difference between the tension F1 and the tension F2 acting respectively towards the end portion (101a) and the end portion (101b) that interposes the portion equivalent to the character line (103) of the metal sheet (101), the friction force being given by the product of: the load P due to the contraction (deformation) of thelateral elastic body of die (11) in the press forming direction, the lateral elastic body of die (11) having been compressed in the press forming step after the contact step of the elastic body; and the friction coefficient μβ between the lateral elastic body of die (11) and the metal sheet (101). In this case, the load P, the friction coefficient μθ and the absolute value |Fi - F2I of the stress difference preferably satisfy the aforementioned equation (2). Press Forming Step The press forming step is, as illustrated in Figure 1(b) to Figure 1(e), a relative movement step of the die (5) towards the punch (3) to bottom dead center, with the punch side contact surface portion (9a) and the die side contact surface portion (11a) held in contact with the sheet metal (101), and obtaining the outer panel (111) of an automobile byformed by pressing, the outer panel (111) having the character line (113) formed therein, by means of the ridge line (3a) and the valley line (5a). Why Slip Lines Are Prevented The following description based on Figures 1(a) to 1(e) and Figure 2 refers to why the press forming method and the press forming apparatus for exterior automotive panels, in accordance with the first embodiment, allow the production of the exterior panel (111) of an automobile, preventing slip lines. First, the die (5) moves relative to the punch (3), the lateral contact surface portion of the punch (9a) of the lateral elastic body of the punch (9) comes into contact with a surface of the portion (107) of the sheet metal (101), the surface being towards the punch (3), before the ridge line (3a) of the punch (3) does, and the lateral contact surface portion of the die(11a) of the elastic body of the side of the die (11) also comes into contact with a surface of the portion (105), the surface being towards the die (5) (Figure 1(a) to Figure 1(b)). Subsequently, in response to further relative movement of the die (5) towards the punch (3), the lateral elastic body of the punch (9) supports the portion (107) by deforming while in contact with the portion (107), and a portion extending from the portion equivalent to the character line (103) to the portion (107) of the sheet metal (101) is gradually subjected to bending deformation to assume a smoothly curved shape (Figure 1(c)). Therefore, even if the ridge line (3a) comes into contact with a portion of the sheet metal (101), the generation of an initial bending defect resulting from the plastic deformation of that portion can be avoided. Subsequently, in the process of greater relative movement of the die (5) towards the punch (3), the bodyThe lateral elastic die (11) comes into contact with portion (105) and deforms, pressing portion (105) against the lateral forming surface portion of the punch (3b) (Figure 1(d)). In this process, in response to the contact of the ridge line (3a) of the punch (3) with the sheet metal (101), stress F1 and stress F2 are generated respectively in directions towards the end portion (101a) and the end portion (101b), the portion equivalent to the character line (103) of the sheet metal (101) being the boundary between stress F1 and stress F2 (Figure 2). Because there is a difference between the tension Fi in the end portion (101a) and the tension F2 in the end portion (101b), slippage from the lower-tension end portion (101a) to the higher-tension end portion (101b) can occur in the metal sheet (101) (see Figures 9(a) to (d)). However, the friction between the lateral elastic body ofThe die (11) and the metal sheet (101) are able to prevent this slippage of the metal sheet (101) towards the larger tension end portion (101a) and to prevent misalignment of the plastically deformed character line portion (103) by the ridge line (3a) (Figure 1(d)), the lateral elastic body of the die (11) having come into contact with the smaller tension portion (105) and having been compressed. As described above, the die (5) is able to move relatively towards the bottom dead center, with: the bending deformation being mitigated by the lateral elastic body of the punch (9), the bending deformation being from the character line portion (103) towards portion (107); and the slippage of the metal sheet (101) being prevented by the lateral elastic body of the die (11), the slippage towards the end portion (101 b) being greater in tension (Figure 1(d) to Figure1(e)). At bottom dead center, the character line (113) is formed by the crest line (3a) of the punch (3) and the valley line (5a) of the die (5), the panel surface portion (117) is formed by the deformation of the punch side contact surface portion (9a) of the punch side elastic body (9), the deformation being a deformation in which the punch side contact surface portion (9a) is flush with the punch side forming surface portion (3c), and the panel surface portion (115) is formed by deformation of the die side contact surface portion (11a) of the die side elastic body (11), the deformation being a deformation in which the die side contact surface portion (11a) is flush with the die side forming surface portion (5b) (Figure 1(e)). As a result, the exterior panel (111) of a car can be obtained by being formed bypressed, having the outer panel (111) the character line (113) formed therein, avoiding slip lines. Another Mode In the press forming method and press forming apparatus described above for exterior automotive panels, in accordance with the first embodiment of the present invention, as illustrated in Figures 1(a) to 1(e), the lateral elastic punch body (9) is supported by the lower part of the groove (3d) and the lateral elastic die body (11) is supported by the lower part of the groove (5d). However, in another mode of the first embodiment, such as a press-forming apparatus (21) illustrated as an example in Figures 3(a) to 3(e), a lateral punch elastic body (9) can be provided in a groove (3d) through a lateral movable punch body (23), and a lateral die elastic body (11) can be provided in a groove (5d) through a lateral movable bodye / cfrnn / eznz / e / Yi of die (25). Figure 3(a) is a state before forming begins, Figure 3(b) is a state where the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) are in contact with the metal sheet (101), Figure 3(c) is a state where the metal sheet (101) is being supported by the lateral elastic body of the punch (9), Figure 1(d) is a state where the metal sheet (101) is being pressed by the lateral elastic body of the die (11), and Figure 1(e) is a state at a bottom dead center. In Figures 3(a) to 3(e), for parts of the press-forming apparatus (21), the same reference symbols as those assigned in Figures 1(a) to 1(e) shall be assigned to any portion that is the same as, or corresponds to, those of the press-forming apparatus (1) illustrated in Figures 1(a) to 1(e). As illustrated in Figures 3(a) to 3(e), the lateral movable punch body (23)It presses the elastic body of the punch side (9) towards a die (5) and supports the elastic body of the punch side (9), and includes: a pad (23a) to which the elastic body of the punch side (9) is attached, the pad (23a) being movable along a press-forming direction; and a pressure source (23b) that causes pressure to be applied to the pad (23a). The pressure source (23b) can be, for example, air pressure, oil pressure, or urethane. The pressure applied by the pressure source (23b) of the movable punch side body (23) to the elastic body of the punch side (9) towards the die (5) is set such that: the elastic body of the punch side (9) compressed in the press-forming process illustrated in Figure 3(b) to Figure 3(e) is pushed back towards the bottom of the groove (3d); and a portion of the lateral contact surface of the punch (9a) of the lateral elastic body of the punch (9) that has been compressedand deformed (contracted) is flush with the lateral forming surface portion of the punch (3c), at the bottom dead center, as illustrated in Figure 3(e). The amount of projection of the lateral elastic punch body (9) supported by the lateral movable punch body (23), from the lateral forming surface portion of the punch (3c), is established, similarly to the first embodiment already described. As illustrated in Figures 3(a) to 3(e), the lateral movable die body (25) presses the lateral elastic die body (11) against a punch (3) and supports the lateral elastic die body (11), and includes: a pad (25a) to which the lateral elastic die body (11) is attached, the pad (25a) being movable along the press forming direction; and a pressure source (25b) that causes pressure to be applied to the pad (25a). The pressure source (25b) can be, for example, air pressure, oil pressure orurethane. The pressure applied by the pressure source (25b) of the lateral die movable body (25) to the lateral die elastic body (11) towards the punch (3) is set so that: the lateral die elastic body (11) compressed in the press forming process illustrated in Figure 3(b) to Figure 3(e) is pushed back towards the bottom of the groove (5d); and a portion of the lateral die contact surface (11a) of the lateral die elastic body (11) that has been compressed and deformed (contracted) is flush with a portion of the lateral die forming surface (5b), at the bottom dead center, as illustrated in Figure 3(e). The number of projections of the lateral elastic die body (11) supported by the lateral movable die body (25), from the lateral die forming surface portion (5b), is established so that, as expressed by the aforementioned Equation (2), theThe frictional force (the product of the load P and the coefficient of friction pe) between the lateral elastic body of the die (11) and the metal sheet (101) is equal to or greater than the absolute value (|Fi - F2I) of the tension difference acting on both sides by inserting the equivalent portion of the character line (103). This load P is the load due to the contraction of the lateral elastic body (11) of the die that has been compressed. The following description refers to the functions and effects of the press forming method and the press forming apparatus for exterior automotive panels, in accordance with this other mode of the first embodiment. In this other mode of the first embodiment, the lateral elastic body of the punch (9) is supported by being pressed by the pressure source (23b) of the movable lateral punch body (23) toward the die (5), as illustrated in Figures 3(a) to 3(e). Therefore, as illustrated in Figure 3(b) to Figure 3(d),Even if the lateral elastic punch body (9) deforms (contracts) due to the relative movement of the die (5) towards the punch (3), the lateral elastic punch body (9) can still make contact with the sheet metal (101) and be supported, with the lateral elastic punch body (9) still pressed towards the die (5). In comparison with the first embodiment (see Figures 1(a) to 1(e)) already described: the adjustment of the pressure by the pressure source (23b) supporting the lateral elastic punch body (9), in addition to the change of material for and / or the shape and size of the lateral elastic punch body (9), causes the bending deformation of a portion to result in a slightly curved shape, the portion being the sheet metal (101) and being where the ridge line (3a) and the lateral contact surface portion of the punch (9a) of the lateral elastic punch body (9) come into contact with; and the one formed by pressing is thus enabled with agreater degree of freedom to avoid the generation of a defective initial bending due to the crest line (3a). In addition, as illustrated in Figures 3(a) to 3(e), the lateral elastic die body (11) in this other mode of the first mode is supported by being pressed by the pressure source (25b) of the lateral movable die body (25) towards the punch (3). Therefore, even in, for example, a case where sufficient frictional force cannot be obtained between the lateral elastic body of the die (11) and the metal sheet (101), or a case where the stress difference (F1 - F2) in the metal sheet (101) becomes large before the load to press the metal sheet (101) by the contraction of the lateral elastic body of the die (11) becomes sufficiently large, there is a greater degree of freedom in adjusting the load by the lateral elastic body of the die (11) to press the metal sheet (101), the adjustment being forThe prevention of slippage of the metal sheet (101) is achieved by applying an additional load from the pressure source (25b) to the pad (25a) to which the lateral elastic die body (11) is attached. As described above, the press forming method and press forming apparatus for automotive exterior panels, in accordance with the other mode of the first embodiment, also allow press forming to obtain the exterior panel (111) of an automobile, the exterior panel (111) having the character line (113) formed thereon, with slip lines effectively prevented. As regards the position in which the metal sheet (101) is pressed by the lateral elastic die body (11) in each of the first mode and the other mode of the first mode, as already described, see Figures 1(a) to 1(e) and Figures 3(a) to 3(e), the lateral elastic die body (11) must entercontact with the portion and press the metal sheet (1) onto the portion (105), along the portion equivalent to the character line (103), at the position of the portion (105), the position being away from the portion equivalent to the character line (103). The groove (5d) is located away from the portion equivalent to the character line (103) and is located on the die-forming side surface portion (5b) that forms the panel surface portion (115), which is comparatively flat and not subject to high stress. Therefore, there is no problem of generating a linear contact defect between a corner of the groove (5d) and a portion close to the portion equivalent to the character line (103), this problem arising in a case where the groove (5d) is provided close to the portion equivalent to the character line (103) as in the technique described in Patent Literature 7. A corner of the groove (5d) forThe lateral elastic body of the die (11) is preferably located away from the valley line (5a) by a distance that is 10% or more of the width of the lateral forming surface portion of the die (5b), the corner being close to the character line equivalent portion (103). Similarly, in the first embodiment and in the other mode of the first embodiment, the position in which the lateral elastic body of the punch (9) presses the metal sheet (101) is set so that the lateral elastic body of the punch (9) that comes into contact with the metal sheet (101) in portion (107), along the character line equivalent portion (103), in a position away from the character line equivalent portion (103) (Figures 1(a) to 1(e) and Figures 3(a) to 3(e)), as already described. Regarding this point, if the lateral elastic punch body (9) is provided in a position close to the portion equivalent to the line ofcharacter (103) as in the technique described in Patent Literature 7, that position is under high tension and is where the character line (113) is formed, and the corner of the groove (3d) will thus tend to come into contact with a portion close to the equivalent portion of the character line (103) and generate a linear defect. Conversely, in each of the first modality and the other mode of the first modality, as illustrated in Figures 1(a) to 1(e) and Figures 3(a) to 3(e), the groove (3d) is in a position away from the equivalent portion of the character line (103) and is located in the portion of the side punch forming surface (3b) that forms the comparatively flat and not high-tension panel surface portion (117). Therefore, there is no problem generating the linear defect; the problem occurs in a case where the slot (3d) is provided close to the portion equivalent to the character line (103) as in theTechnique described in Patent Literature 6. A corner of the groove (3d) for accommodating the lateral punch spring body (9) is preferably separated from the ridge line (3a) by a distance that is 10% or more of the width of the lateral punch forming surface portion (3c), the corner being close to the portion equivalent to the character line (103). Additionally, in the press forming of the sheet metal (101) into the outer panel (111) of an automobile as illustrated in Figures 1(a) to 1(e) and Figures 3(a) to 3(e) in accordance with the first embodiment and the other mode of the first embodiment, the order in which the lateral punch spring body (9) and the lateral die spring body (11) are brought into contact with the sheet metal (101) is not particularly restricted. Specifically, provided that the amount of projection of the lateral elastic body of the punch (9) is set so that the lateral elastic body ofpunch (9) comes into contact with the metal sheet (101) before the ridge line (3a) of the punch (3) comes into contact with the metal sheet (101) and the amount of protrusion of the lateral elastic body of the die (11) is established such that the lateral elastic body of the die (11) comes into contact with the metal sheet (101) before the ridge line (3a) of the punch (3) comes into contact with the metal sheet (101) and plastic deformation occurs: the lateral elastic body of the punch (9) may come into contact with the metal sheet (101) first; the lateral elastic body of the die (11) may come into contact with the metal sheet (101) first; or the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) may come into contact with the metal sheet (101) at the same time. Second Modality In the first modality described above of the present invention, as illustrated in Figures 1(a) to 1(e) In the process of forming by pressing the metal sheet (101) into the outer panel (111) of an automobile, the lateral elastic body of the punch (9) is brought into contact with the larger portion (107) in tension, to hold the portion (107), the portion (107) being on one side of a portion equivalent to the character line (103), and the lateral elastic body of the die (11) is brought into contact with the smaller portion (105) in tension to press the portion (105), the portion (105) being on the other side of the portion equivalent to the character line (103). e / cfrnn / eznz / e / Yi On the contrary, in the press forming apparatus and press forming method for exterior automotive panels, according to the second embodiment of the present invention, as in a press forming apparatus (31) illustrated as an example in Figures 4(a) to 4(e), in the process of press forming a metal sheet (101) into an exterior panel (111) of aautomobile, a lateral elastic punch body (9) is made in contact with a portion (105) of the metal sheet (101), to support the portion (105), the portion (105) being less in tension, and a lateral elastic die body (11) is made in contact with a portion (107) of the metal sheet (101), to press the portion (107), the portion (107) being greater in tension. Figure 4(a) shows a state before forming begins, Figure 4(b) shows a state where the punch lateral spring body (9) and the die lateral spring body (11) are in contact with the sheet metal (101), Figure 4(c) shows a state where the sheet metal (101) is being supported by the punch lateral spring body (9), Figure 4(d) shows a state where the sheet metal (101) is being pressed by the die lateral spring body (11), and Figure 4(e) shows a state at bottom dead center. In Figures 4(a) to 4(e), for the parts of the apparatus ofFormed by pressing (31), the same reference signs as those assigned in Figures 1(a) to 1(e) shall be assigned to any part that is equal to and any part that corresponds to those of the pressing forming apparatus (1) illustrated in Figures 1(a) to 1(e). As illustrated in Figures 4(a) to 4(e), the lateral punch spring body (9) is provided in the groove (3d) so that the lateral punch spring body (9) projects into a die (5) that is a portion of the lateral punch forming surface (3b) and is thus able to make contact with the sheet metal (101) in portion (105), along the portion equivalent to the character line (103), in a position away from the portion equivalent to the character line (103). As illustrated in Figures 4(a) to 4(e), the lateral die spring body (11) is provided in the groove (5d) so that the lateral die spring body (11) protrudes into the punch (3) more thana portion of the die's side forming surface (5c) and thus comes into contact with and presses the sheet metal (101) onto the portion (107), along the portion equivalent to the character line (103), in a position away from the portion equivalent to the character line (103). The amount of projection of the punch's side spring body (9) from the punch's side forming surface portion (3b) and the amount of projection of the die's side spring body (11) from the die's side forming surface portion (5c) are adjusted respectively, similarly to those of the first embodiment already described. As illustrated in Figures 4(a) to 4(e), the press-forming method for automotive exterior panels, according to the second embodiment, is, similarly to the first embodiment illustrated in Figures 1(a) to 1(e), for press-forming the sheet metal (101) into the exterior panel (111) of aautomobile, the outer panel (111) has a character line (113) and a continuous surface portion of panel (115) and a surface portion of panel (117) on both sides of the character line (113), using the press forming apparatus (31) which includes the punch (3), the die (5), a blank holder, the punch side spring body (9), and the die side spring body (11), and the press forming method includes a spring body contact step and a press forming step. The contact step of the elastic body is, as illustrated in Figure 4(a) to Figure 4(b), a relative movement step of the die (5) toward the punch (3) in a state where an end portion (101a) and an end portion (101b) at both ends of the sheet metal (101) are being sandwiched between the die (5) and the blank holder (7), and bringing each of the portions into contact.lateral contact surface of the punch (9a) of the lateral elastic punch body (9) and a portion of the lateral contact surface of the die (11a) of the lateral elastic die body (11) with the metal sheet (101). The press forming step is, as illustrated in Figure 4(b) to Figure 4(e), a relative movement step of the die (5) towards the punch (3) to the bottom dead center, with the portion of lateral contact surface of the punch (9a) and the portion of lateral contact surface of the die (11a) remaining in contact with the metal sheet (101), and the press forming of the metal sheet (101) into the outer panel (111) of an automobile, the outer panel (111) having the character line (113) formed therein, by means of the ridge line (3a) and the valley line (5a). Why Sliding Lines Are Prevented The following description, based mainly on Figures 4(a) to 4(e), deals with why theThe press forming method and press forming apparatus for automotive exterior panels, according to the second embodiment, allow the production of an automotive exterior panel (111) by press forming, avoiding slip lines. First, the die (5) moves relative to the punch (3), the elastic body of the punch (9) provided in the lateral forming surface portion of the punch (3b) comes into contact with the metal sheet (101) on the punch side (3) of portion (105) before the ridge line (3a) of the punch (3) does, and the elastic body of the die (11) provided in the lateral forming surface portion of the die (5c) comes into contact with the metal sheet (101) on the die side (5) of portion (107). (Figure 4(a) to Figure 4(b)). Subsequently, moving the die (5) relatively towards the punch (3), with the lateral contact surface portion of the punch (9a)Being in contact with and supporting the portion (105) on the surface towards the punch (3), and the lateral contact surface portion of the die (11a) being in contact with and pressing the portion (107), cause the ridge line (3a) of the punch (3) to come into contact with the portion equivalent to the character line (103) of the sheet metal (101) (Figure 4(c)). Subsequently, the relative movement of the die (5) towards the punch (3) causes the lateral elastic body of the punch (9) to deform further as the press forming progresses. Therefore, bending deformation occurs gradually to form a smoothly curved shape in a range from the portion equivalent to the character line (103) with which the ridge line (3a) comes into contact to the portion (105) with which the lateral elastic body of the punch (9) comes into contact. This prevents the generation of an initial bending defect resulting from theplastic deformation caused in the event that the ridge line (3a) comes into contact with the metal sheet (101) before the lateral elastic body of the die (11) presses the portion (107). Likewise, in the process of subsequent relative movement of the die (5) towards the punch (3), friction allows: the prevention of slippage of the metal sheet (101) towards the larger end portion (101b) in tension; and the prevention of misalignment of the portion equivalent to the character line (103) plastically deformed by the ridge line (3a) (Figure 4(c) to Figure 4(d)), the friction being between the metal sheet (101) and the lateral elastic body of the die (11) that has come into contact with the larger portion (107) in tension and has been compressed. As described above, the die (5) is capable of being moved relatively towards the bottom dead center, with: bending deformation being mitigated by the lateral elastic body of the punch(9) over a range from the portion equivalent to the character line (103) to the portion (105); and the lateral elastic die body (11) preventing the slippage of the metal sheet (101) towards the larger end portion (101b) in tension (Figure 4(d) to Figure 4(e)). At bottom dead center, the character line (113) is formed by the crest line (3a) of the punch (3) and the valley line (5a) of the die (5), the panel surface portion (115) is formed by the deformation of the punch side contact surface portion (9a) of the punch side spring body (9), the deformation being a deformation in which the punch side contact surface portion (9a) is flush with the punch side forming surface portion (3b), and the panel surface portion (117) is formed by the deformation of the die side contact surface portion (11a) of the die side spring body (11), theDeformation is a deformation in which the lateral contact surface portion of the die (11a) is flush with the lateral forming surface portion of the die (5c). As a result, the outer panel (111) of an automobile can be obtained by press forming, the outer panel (111) having the character line (113) formed on it, avoiding slip lines. Another Mode In the press forming method and press forming apparatus described above for exterior automotive panels, according to the second embodiment of the present invention, as illustrated in Figures 4(a) to 4(e), the lateral elastic body of the punch (9) is supported by the lower part of the groove (3d) formed in the lateral forming surface portion of the punch (3b), and the lateral elastic body of the die (11) is supported by the lower part of the groove (5d) formed in the forming surface portion.side of the die (5c). However, in another mode of the second embodiment, such as a press forming apparatus (41) illustrated as an example in Figures 5(a) to 5(e), a lateral elastic punch body (9) can be supported by the bottom of a groove (3d) through a movable lateral punch body (23), and a lateral elastic die body (11) can be supported by the bottom of a groove (5d) through a movable lateral die body (25). Figure 5(a) is a state before forming begins, Figure 5(b) is a state in which the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) are in contact with a metal sheet (101), Figure 5(c) is a state in which the metal sheet (101) is being supported by the lateral elastic body of the punch (9), Figure 5(d) is a state in which the metal sheet (101) is being pressed by the lateral elastic body of the die (11), and Figure5(e) is a state at bottom dead center. In Figures 5(a) to 5(e), for the parts of the press-forming apparatus (41), the same reference signs as those assigned in Figures 1(a) to 1(e) shall be assigned to any portions that are equal and any portions that correspond to those of the press-forming apparatus (1) illustrated in Figures 1(a) to 1(e). In this other mode of the second embodiment, the amount of projection of the lateral punch spring body (9) from a portion of the lateral punch forming surface (3b) and the amount of projection of the lateral die spring body (11) from a portion of the lateral die forming surface (5c) are respectively established in a manner similar to that of the other mode of the first embodiment already described. Consequently, because the lateral elastic punch body (9) is supported by the lateral movable punch body (23), in the polished press forming processIn Figures 5(b) through 5(d), similarly to the other mode described above for the first modality, press forming is permitted with a greater degree of freedom to prevent the generation of an initial bending defect through bending deformation, resulting in a smoothly curved shape. This bending deformation occurs in a portion of the sheet metal (101), specifically the portion where a ridge line (3a) and a portion of the lateral contact surface of the punch (9a) of the lateral punch elastic body (9) come into contact. Furthermore, because the lateral die elastic body (11) is supported by the lateral movable die body (25), in the press forming process illustrated in Figures 5(b) through 5(e), similarly to the other mode described above for the first modality, there is a greater degree of freedom for load adjustment by the lateral die elastic body (11).Press the portion (107) to prevent slippage of the metal sheet (101). As described above, the press forming method and press forming apparatus for automotive exterior panels, in accordance with the other mode of the e / cfrnn / eznz / e / Yi second mode, also allow press forming to obtain the exterior panel (111) of an automobile, the exterior panel (111) having the character line (113) formed therein, thus more effectively preventing slip lines. A corner of the groove (3d) (Figures 4(a) to 4(e) and Figures 5(a) to 5(e)) for accommodating the lateral elastic punch body (9) is preferably separated from the ridge line (3a) by a distance that is 10% or more of the width of the lateral punch forming surface portion (3b), the corner being close to the character line (113). A corner of the slot (5d) (Figures 4(a) to 4(e) and Figures 5(a) to 5(e)) to accommodate the elastic bodyThe die side (11) is preferably separated from a valley line (5a) by a distance that is 10% or more of the width of the die side forming surface portion (5c), with the corner being close to the character line (113). Consequently, the problem of generating a linear contact defect between the corner of the groove (3d) or the corner of the groove (5d) and a portion close to the portion equivalent to the character line (103) does not occur, as is the case, for example, in the technique described in the aforementioned Patent Literature 7. Furthermore, in the process of press forming the metal sheet (101) into the exterior panel (111) of an automobile by means of press forming methods and press forming apparatus for exterior automotive panels, in accordance with the second embodiment and the other mode of the second embodiment, similarly to the first embodiment and the other mode of the firstIn the manner already described, the order in which the lateral elastic body of the punch (9) and the lateral elastic body of the die (11) come into contact with the metal sheet (101) is not particularly limited. A groove for housing a lateral elastic body of the punch, according to the present invention, must have a greater width than that of the lateral elastic body of the punch, to accommodate the deformation of the lateral elastic body of the punch during the press forming process. Similarly, a groove for housing a lateral elastic body of the die must have a greater width than that of the lateral elastic body of the die, to accommodate the deformation of the lateral elastic body of the die during the press forming process. EXAMPLES The following description concerns examples implemented to validate the effect of preventing slip lines on the formation of a character line in obtaining an exterior panel of an automobile byFormed by press forming using a press forming method and a press forming apparatus for exterior automotive panels, according to the present invention. In Examples, it was verified whether or not a slip line was generated on an exterior panel obtained by press forming through a press forming analysis in which the exterior panel was obtained by press forming using a press forming method of e / cfrnn / eznz / e / Yi according to the present invention, simulating the exterior panel of an automobile, the exterior panel having a character line. In the press forming analysis, an SGCC-F steel sheet with a thickness of 0.7 mm was used as the metal sheet, and the object to be analyzed was an exterior panel (121) illustrated in Figure 6 and having a character line (123) and a panel surface portion (125) and a panel surface portion (127) that are bothsides of the continuous character line (123). The character line (123) had a radius of curvature of 3 mm, the angles of the panel surface portion (125) and the panel surface portion (127) with respect to a press-forming direction were respectively (0a) = 85° and (0b) = 65°, the widths of the panel surface portion (125) and the panel surface portion (127) (lengths from the boundary of the character line to their ends) were both 50 mm. In the Conventional Example of Examples, a press-forming analysis of a deep-drawing process of a sheet metal in an exterior panel (see Figures 9(a) to 9(d)) was performed by means of a press-forming apparatus that includes a punch, a die, and a blank holder. The difference in tension generated in the pressing process between the portion of the panel surface (127) with a smaller angle ((0t>) = 65°) and the portion of the surface ofpanel (125) with a larger angle ((0a) = 85°) was 202 kN. Next, in the Example of the invention, a press forming analysis of a metal sheet (101) into an outer panel (121) (Figure 6) was carried out using a press forming apparatus (1) comprising a punch (3), a die (5), a blank holder (7), a punch side spring body (9) and a die side spring body (11), as illustrated in Figures 1(a) to 1(e). In the press forming analysis, the punch side spring body (9) was provided in a groove (3d) of a punch side forming surface portion (3c), to project into the die (5) from the punch side forming surface portion (3c). The punch side spring body (9) has been adjusted to contact a portion corresponding to the panel surface portion (127) at a smaller acute angle with respect to the press forming direction, the portion being in a position away from a character line equivalent portion (103) corresponding to character line (123) (the limit of the punch groove (3d) is in a position that is 10% of the width of the punch side forming surface portion (3c), the limit being close to the character line equivalent portion (103)).The amount of projection of the lateral elastic body of the punch (9) from the lateral forming surface portion of the punch (3c) was fixed at 5 mm, so that the lateral contact surface portion of the punch (9a) would come into contact with the metal sheet (101) before a ridge line (3a) of the punch (3) would come into contact with the metal sheet (101). e / cfrnn / eznz / e / Yi The lateral die spring (11) was provided with a groove (5d) in a lateral die forming surface portion (5b), to project towards the punch (3) from the lateral die forming surface portion (5b). The lateral die spring (11) was then brought into contact with and pressed a corresponding portion of the panel surface portion (125) at a greater acute angle with respect to the press forming direction, the portion being in a position away from the portion equivalent to the character line (103) (a limit of the groove (5d) of the die (5) is in a position that is 10% of the width of the lateral die forming surface portion (5b), the limit being close to the portion equivalent to the character line (103)).The amount of overhang of the lateral elastic body of the die (11) from the lateral forming surface portion of the die (5b) was set at 12 mm based on a tension difference (= 202 kN) acting on both sides by inserting the equivalent portion to the character line (103) in the press forming process in accordance with the Conventional Example (see Figures 9(a) to 9(d)). In the press forming analysis, the punch lateral elastic body (9) and the die lateral elastic body (11) were both made of hard urethane and the coefficients of friction between the metal sheet (101) and the punch lateral elastic body (9) and the die lateral elastic body (11) were both 0.6, and the punch lateral elastic body (9) and the die lateral elastic body (11) both had an elastic modulus of 253 N / mm. Figure 7 illustrates the results of the cross-sectional shapes of the exterior panels (121) obtained through press forming analyses.Figure 7 illustrates the enlarged cross-sectional shapes of portions of the outer panels (121), the portions being around the character lines (123), in a coordinate plane having a horizontal axis representing a horizontal direction (= the width direction of the panel surface portion (127)) parallel to the panel surface portion (127) and a vertical axis representing a direction (= the press-forming direction) orthogonal to the panel surface portion (127), the cross-sectional shapes of the outer panels (121) being arranged to be rotated so that the smaller panel surface portions (127) angled with respect to the press-forming direction become horizontal, as illustrated in Figure 6. From Figure 7, in contrast to the Example of the invention, concavity and convexity (portions surrounded by dotted ellipses in Figure 7) caused by a slip line in the largest portion of panel surface (127) under tension per unit area were observed in the Conventional Example. Figure 8 illustrates the results of the surface deflection evaluation of the outer panels (121) obtained in the press-forming analyses. Figure 8 is a graph having a horizontal axis representing the horizontal coordinates of the panel surface portions (127) when the smaller portions of the panel surface (127) at acute angles to the press-forming direction are arranged to be horizontal, and a vertical axis representing the evaluation value As for the surface deflection at each horizontal position. The As evaluation value for surface deflection is represented by, as described in the following publicly known reference, a difference between the maximum and minimum mountain height measured by a three-point meter (fixed span L). Reference: The Japan Sheet Metal Forming Research Group, Fourth Edition of Press Forming DifficuIty Handbook, Chapter 5 Poor Surface Shape Precision and Evaluation of DifficuIty of Forming, pp. 218-221, Nikkan Kogyo Shimbun, Ltd. (2017). From Figure 8, the difference between the maximum and minimum of the As evaluation value for surface deviation was 0.017 in the Conventional Example and 0.006 in the Example of the Invention. It can thus be understood that the lateral elastic body of the punch (9) came into contact with the metal sheet (101) and supported the metal sheet (101) so that the bending deformation resulted in a slightly curved shape, the lateral elastic body of the die (11) pressed the metal sheet (101) for press forming, and the surface deviation in the panel surface portion (127) was thus reduced. As described above, the present invention has been shown to enable the production of an exterior panel of an automobile by pressing and forming, avoiding slip lines, with the exterior panel having a character line formed therein. Figures 7 and 8 illustrate results for a case in which the lateral elastic body of punch (9) was provided for a portion (107) of the metal sheet (101), the portion (107) being of greater tension, and the lateral elastic body of die (11) was provided for a portion (105) of the metal sheet (101), the portion (105) being of lesser tension, similarly to the first modality already described. Press forming analyses were performed similarly for one case (Figures 4(a) to 4(e)) where the lateral punch spring (9) was provided for the lower-stress portion (105) and the lateral die spring (11) was provided for the higher-stress portion (107), and for another case (Figures 3(a) to 3(e) and Figures 5(a) to 5(e)) where the lateral punch spring (9) was supported by a lateral movable punch spring (23) and the lateral die spring (11) was supported by a lateral movable die spring (25). The results of these press forming analyses are not illustrated in the drawings, but in both cases, it was confirmed that press forming was possible without slip lines being produced, with the press forming of an exterior panel having a character line formed on it. INDUSTRIAL APPLICATION The present invention provides a method of press forming and a press forming apparatus for exterior automotive panels, for the formation of specific character lines, preventing slip lines without increasing man-hours for press forming. LIST OF REFERENCE SIGNS (1) PRESS FORMING APPARATUS (3) PUNCH (3a) CREST LINE (3b) PORTION OF SIDE FORMING SURFACE OF PUNCH (3c) PORTION OF SIDE FORMING SURFACE OF PUNCH (3d) GROOVE (5) DIE (5a) VALLEY LINE (5b) PORTION OF SIDE FORMING SURFACE OF DIE (5c) PORTION OF SIDE FORMING SURFACE OF DIE (5d) GROOVE (7) BLANK SUPPORT (9) SIDE ELASTIC BODY OF PUNCH (9a) PORTION OF SIDE CONTACT SURFACE OF PUNCH (11) SIDE ELASTIC BODY OF DIE (11a) PORTION OF SURFACE OF SIDE DIE CONTACT (21) PRESS FORMING APPARATUS (23) SIDE MOVABLE PUNCH BODY (23a) PAD (23b) PRESSURE SOURCE (25) SIDE MOVABLE DIE BODY (25a) PAD (25b) PRESSURE SOURCE (31) PRESS FORMING APPARATUS (41) PRESS FORMING APPARATUS (51) PRESS FORMING APPARATUS (CONVENTIONAL TECHNIQUE (53) PUNCH (53a) CREST LINE (55)DIE (55a) VALLEY LINE (57) BLANK SUPPORT e / cfrnn / eznz / e / Yi (101) SHEET METAL (101a) END PORTION (101b) END PORTION (103) EQUIVALENT PORTION OF CHARACTER LINE (105) PORTION (107) PORTION (111) AUTOMOBILE EXTERIOR PANEL (113) CHARACTER LINE (115) PANEL SURFACE PORTION (117) PANEL SURFACE PORTION (121) EXTERIOR PANEL (EXAMPLE) (123) CHARACTER LINE (125) PANEL SURFACE PORTION (127) SURFACE PORTION OF PANEL

Claims

1. A press forming method for an automotive exterior panel, for press forming a sheet metal into the automotive exterior panel, the exterior panel having a character line and a panel surface portion that is on both sides of the character line and continuous, using a punch, a punch-oriented die, and a blank holder oriented towards die end portions, wherein the punch includes: a ridge line for forming the character line; a punch side forming surface portion for forming the panel surface portion;and a lateral elastic body of the punch supported to project into the die more than the lateral forming surface portion of the punch, so that the lateral elastic body of the punch can come into contact with the sheet metal, along a portion equivalent to the character line corresponding to the character line on the sheet metal, in a position away from the portion equivalent to the character line, on a greater side in tension by pressing forming between portions on both sides interposing the portion equivalent to the character line, and the die includes: a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the panel surface portion;and a lateral elastic body of the die supported to project towards the punch more than the lateral forming surface portion of the die, so that the lateral elastic body of the die comes into contact with the sheet metal and presses it, along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a lesser side under pressure tension formed between portions on both sides interposing the portion equivalent to the character line, the press forming method comprising: a contact step of the elastic body of moving the die relatively towards the punch in a state in which both end portions of the sheet metal are interposed between the die and the blank holder, and bringing each of the lateral elastic body of the punch and the lateral elastic body of the die into contact with the sheet metal;and a forming step by pressing the sheet metal into the exterior automotive panel, the exterior panel having the character line formed by means of the ridge line and the valley line, moving the die relatively towards the punch to a bottom dead center with the lateral punch spring body and the lateral die spring body both being in contact with the sheet metal, wherein: a quantity of projection of the lateral punch spring body is established from the lateral forming surface portion of the punch so that the lateral punch spring body: comes into contact with the sheet metal before the ridge line of the punch comes into contact with the sheet metal in the spring body contact step;and is flush with the side forming surface portion of the punch at the bottom dead center, and a quantity of lateral die spring body projection is established from the side forming surface portion of the die such that: the lateral die spring body comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal and the sheet metal is plastically deformed at the spring body contact step; and a frictional force given by the product of: a load from the lateral die spring body pressing the sheet metal at the pressure forming step; and a coefficient of friction between the lateral die spring body and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line.

2. A press forming method for an exterior panel of an automobile, for press forming a sheet metal into the exterior panel of the automobile, the exterior panel having a character line and a continuous panel surface portion on both sides of the character line, using a punch, a die oriented towards the punch, and a blank holder oriented towards the extreme portions of the die, wherein the punch includes: a ridge line for forming the character line; a side punch forming surface portion for forming the panel surface portion;and a lateral elastic body of the punch supported to project into the die more than the lateral forming surface portion of the punch, so that the lateral elastic body of the punch can come into contact with the sheet metal, along a portion equivalent to the character line corresponding to the character line on the sheet metal, in a position away from the portion equivalent to the character line, on a minor side under pressure tension formed between portions on both sides interposing the portion equivalent to the character line, and the die includes: a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the surface portion of the panel;and a lateral elastic body of the die supported to project towards the punch more than the lateral forming surface portion of the die, so that the lateral elastic body of the die comes into contact with and presses the sheet metal along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a greater side under pressure tension formed between portions on both sides interposing the portion equivalent to the character line, the method of forming by pressing, comprising: an elastic body contact step of moving the die relatively towards the punch in a state in which the two end portions of the sheet metal are interposed between the die and the blank support, and bringing each of the lateral elastic bodies of the punch and lateral of the die into contact with the sheet metal;and a pressing forming step to form the sheet metal into the exterior panel of the automobile, the exterior panel having the character line formed by means of the crest line and the valley line, moving the die relatively towards the punch to a bottom dead center with the lateral spring body of the punch and the lateral spring body of the die both being in contact with the sheet metal, wherein an amount of projection of the lateral spring body of the punch is established from the lateral forming surface portion of the punch so that the lateral spring body of the punch: comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal;and is flush with the side forming surface portion of the punch at the bottom dead center, and a quantity of lateral die spring body projection is established from the side forming surface portion of the die such that: the lateral die spring body comes into contact with the sheet metal before the punch ridge line comes into contact with the sheet metal and the sheet metal is plastically deformed at the spring body contact step; and a frictional force given by the product of: a load from the lateral die spring body pressing the sheet metal at the pressure forming step; and a coefficient of friction between the lateral die spring body and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line.

3. The press forming method for the automotive exterior panel according to claim 1 or 2, wherein the lateral elastic punch body is movable along a press forming direction and is provided in the punch by means of a movable lateral punch body that supports the lateral elastic punch body by pressing the lateral elastic punch body towards the die.

4. The press forming method for the automotive exterior panel according to any of claims 1 to 3, wherein the lateral die elastic body is movable along a press forming direction and is provided in the die by means of a movable lateral die body that supports the lateral die elastic body by pressing the lateral die elastic body towards the punch.

5. A press forming apparatus for an exterior panel of an automobile, for press forming a sheet metal into the exterior panel of the automobile, the exterior panel having a character line and a continuous panel surface portion on both sides of the character line, the press forming apparatus comprising: a punch; a die oriented towards the punch; and a blank holder oriented towards the end portions of the die, wherein the punch includes: a ridge line for forming the character line; a side punch forming surface portion for forming the panel surface portion;and a lateral elastic punch body supported to project into the die more than the lateral forming surface portion of the punch, so that the lateral elastic punch body can make contact with the sheet metal along a portion equivalent to the character line corresponding to the character line of the sheet metal, in a position away from the portion equivalent to the character line, on a pressing-strength side formed between portions on both sides interposing the portion equivalent to the character line, and the die includes: a valley line to form the character line in cooperation with the ridge line; a lateral forming surface portion of the die to form the panel surface portion;a lateral elastic body of the die supported to project towards the punch more than the lateral forming surface portion of the die, such that the elastic body on the die side comes into contact with and presses the sheet metal, along the equivalent portion of the character line, in a position away from the equivalent portion corresponding to the character line, on a side of less pressing stress formed between portions on both sides that interpose the equivalent portion of the character line, wherein an amount of projection of the lateral elastic body of the punch is established from the lateral forming surface portion of the punch so that the lateral elastic body of the punch: comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal when the die is moved relative to the punch;and is flush with the side forming surface portion of the punch at a bottom dead center, and a quantity of projection of the side spring body of the die is established from the side forming surface portion of the die such that: the side spring body of the die comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal, and the sheet metal is plastically deformed when the die moves relative to the punch; and a frictional force, given by the product of: a load of the side spring body of the die pressing on the sheet metal; and a coefficient of friction between the side spring body of the die and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line.

6. A press-forming apparatus for an exterior panel of an automobile, for press-forming a sheet metal into the exterior panel of an automobile, the exterior panel having a character line and a panel surface portion that is on both sides of the character line and is continuous, using a punch, a punch-oriented die, and a blank holder oriented towards the end portions of the die, wherein a punch; a punch-oriented die, wherein the punch includes: a ridge line for forming the character line; a side forming surface portion of the punch for forming the panel surface portion;and a lateral elastic punch body supported to project into the die more than the lateral forming surface portion of the punch, so that the lateral elastic punch body can make contact with the sheet metal, along a portion equivalent to the character line corresponding to the character line of the sheet metal, in a position away from the portion equivalent to the character line, on a side of lesser pressing stress formed between portions on both sides interposing the portion equivalent to the character line, and the die includes: a valley line for forming the character line in cooperation with the ridge line; a lateral forming surface portion of the die for forming the panel surface portion;a lateral elastic body of the die supported to project towards the punch more than the lateral forming surface portion of the die, so that the lateral elastic body of the die comes into contact with and presses the sheet metal, along the portion equivalent to the character line, in a position away from the portion equivalent to the character line, on a greater pressing tension side formed between portions on both sides interposing the portion equivalent to the character line, wherein an amount of projection of the lateral elastic body of the punch is established from the lateral forming surface portion of the punch so that the lateral elastic body of the punch: comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal when the die is moved relative to the punch;and is flush with the side forming surface portion of the punch at a bottom dead center, and a quantity of lateral die spring body projection is established from the side forming surface portion of the die such that: the lateral die spring body comes into contact with the sheet metal before the crest line of the punch comes into contact with the sheet metal, and the sheet metal is plastically deformed when the die moves relative to the punch; and a frictional force, given by the product of: a load on the lateral die spring body pressing on the sheet metal; and a coefficient of friction between the lateral die spring body and the sheet metal, is made equal to or greater than an absolute value of a difference between the stresses acting on the portions on both sides that interpose the portion equivalent to the character line.

7. The press forming apparatus for the exterior automotive panel according to claim 5 or 6, wherein the lateral elastic punch body can be moved along a press forming direction and is provided in the punch by means of a movable lateral punch body that supports the lateral elastic punch body by pressing the lateral elastic punch body towards the die.

8. The press forming apparatus for the exterior automotive panel according to any of claims 5 to 7, wherein the lateral elastic die body is movable along a press forming direction and is provided in the die by means of a movable lateral die body that supports the lateral elastic die body by pressing the lateral elastic die body towards the punch.

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