JP6699207B2 - Press apparatus, method for manufacturing press-formed product using the same, and die - Google Patents

Description

  The present invention relates to a pressing device, a method for manufacturing a press-formed product using the pressing device, and a die that can be used in the pressing device.

  By pressing a metal plate, pressed products of various shapes are manufactured. Conventionally, it has been attempted to reduce the thickness of a pressed product by using a high-strength steel plate, thereby reducing the weight of the pressed product. However, since the high-tensile steel plate has low ductility, when an article having a curved portion (a lower arm of an automobile, etc.) is press-formed, a forming defect such as a break or a wrinkle easily occurs. In particular, when press-molding an article having a stretch flange portion, breakage easily occurs at the stretch flange end portion.

  An example of bending the stretch flange portion is schematically shown in FIGS. 8A to 8C. 8A shows a state before the start of molding, FIG. 8B shows a state during molding, and FIG. 8C shows a state at the final stage of molding. In this bending, the metal plate 3 is sandwiched between the die 1 and the punch 2 and is bent. In the bent metal plate 3, the deformation at the ridge 3a is small, but the elongation at the end 3b is large. Therefore, in bending, cracks are likely to occur at the end 3b of the metal plate 3.

  9A to 9C schematically show an example of drawing the stretch flange portion. 9A shows a state before the start of molding, FIG. 9B shows a state in the middle of molding, and FIG. 9C shows a state at the final stage of molding. In this draw forming, the metal plate 3 is sandwiched between the die 1, the punch 2 and the blank holder 4 and draw formed. In the drawn metal plate 3, the elongation rate at the end portion 3b is small, but the deformation at the ridge line portion 3a is large. Therefore, in draw forming, cracks are likely to occur in the ridgeline portion 3a of the metal plate 3.

  One of the methods for preventing cracks in bending is disclosed in Japanese Unexamined Patent Publication No. 2015-100812 (Patent Document 1). The component molded by the method of Patent Document 1 has a concave outer peripheral edge portion in which a part of the outer peripheral edge is inwardly recessed. The method of Patent Document 1 is a step of pressing the blank material at a distance of 10 times or more and 100 times or less of the plate thickness of the blank material before processing from the R stop of the concave outer peripheral edge portion, and bending the blank material in that state. And a step of performing.

  One of methods for preventing defects in draw forming is disclosed in Japanese Patent Laid-Open No. 6-87039 (Patent Document 2). The method of Patent Document 2 includes a step of performing a drawing process by setting a large drawing angle radius.

  It is a conventional problem to further reduce the occurrence of defects in press molding. In particular, when a high-strength steel plate is used, defects in press molding are likely to occur. For example, when stretch flange forming is performed, cracks are likely to occur at the flange end and the ridge. Therefore, there is a demand for a new method capable of suppressing the occurrence of molding defects in press molding.

JP, 2015-100812, A JP, 6-87039, A

  In the above situation, one of the objects of the present invention is to provide a press device capable of suppressing the occurrence of molding defects in press molding, a method for manufacturing a press molded product using the same, and a die.

  A pressing device according to an embodiment of the present invention includes a die main body including a first convex portion having a first plate pressing surface, and a concave portion adjacent to a shoulder portion of the first convex portion, and the first main body. A pressing member that is arranged on the opposite side of the recess with the plate pressing surface interposed therebetween, includes a second plate pressing surface, and has a shoulder portion on the first plate pressing surface side, and supports the pressing member, and presses the pressing member. A first support mechanism that is expandable/contractible in a direction, a punch that is disposed so as to face the die body in the pressing direction, and has a second convex portion that corresponds to the concave portion; and the first plate pressing surface. And a blank holder arranged to face both the second plate pressing surface in the pressing direction.

A manufacturing method according to an embodiment of the present invention is a method for manufacturing a press-formed product using the pressing device of the present invention. This manufacturing method is
(I) sandwiching a metal plate between the blank holder and the second plate pressing surface of the pressing member protruding from the first plate pressing surface of the first convex portion;
(Ii) By pressing the die body and the punch close to each other with the second plate pressing surface still protruding from the first plate pressing surface, the shoulder of the first convex portion and the pressing Bending the metal plate at the shoulder of the member,
(Iii) by bringing the die body and/or the punch closer to the die body and/or the die plate and/or the punch while bringing the second plate pressing surface closer to the first plate pressing surface. Molding the plate.

  A die according to an embodiment of the present invention includes a die body including a convex portion having a first plate pressing surface, a concave portion adjacent to a shoulder portion of the convex portion, and a die body sandwiching the first plate pressing surface. The pressing member is disposed on the side opposite to the concave portion, has a second plate pressing surface, and has a shoulder portion on the side of the first plate pressing surface, and is arranged between the die body and the pressing member. A support mechanism that supports the pressing member and is capable of expanding and contracting in the pressing direction.

  According to the present invention (press device, manufacturing method, and die), it is possible to suppress the occurrence of molding defects in press molding.

FIG. 1 is a perspective view schematically showing an example of a mold set including the die of the present invention. FIG. 2 schematically shows a cross section of a part of the mold set shown in FIG. FIG. 3 schematically shows another part of the mold set shown in FIG. FIG. 4A is a sectional view schematically showing a step of an example of the method of the present invention for producing a press-formed product. FIG. 4B is a cross-sectional view schematically showing an example of the step following FIG. 4A. FIG. 4C is a cross-sectional view schematically showing an example of the step following FIG. 4B. FIG. 4D is a cross-sectional view schematically showing an example of the step following FIG. 4C. FIG. 5 is a perspective view schematically showing an example of a press-formed product manufactured by the manufacturing method of the present invention. FIG. 6 is a graph showing the evaluation results of stretch flange forming by the conventional manufacturing method and the manufacturing method of the present invention. FIG. 7A is a sectional view schematically showing a step of another example of the method of the present invention for producing a press-formed product. 7B is a cross-sectional view schematically showing an example of the step following FIG. 7A. FIG. 7C is a cross-sectional view schematically showing an example of the step following FIG. 7B. FIG. 7D is a cross-sectional view schematically showing an example of the step following FIG. 7C. FIG. 8A is a cross-sectional view schematically showing a step of an example of a conventional method of bending and forming a stretch flange portion. FIG. 8B is a cross-sectional view schematically showing an example of the step following FIG. 8A. FIG. 8C is a cross-sectional view schematically showing an example of the step following FIG. 8B. FIG. 9A is a cross-sectional view schematically showing a step of an example of a conventional method for drawing a stretch flange portion. 9B is a cross-sectional view schematically showing an example of the step following FIG. 9A. FIG. 9C is a cross-sectional view schematically showing an example of the step following FIG. 9B.

  Hereinafter, embodiments of the present invention will be described. In the following description, the embodiments of the present invention will be described with examples, but the present invention is not limited to the examples described below. Although specific numerical values and materials may be exemplified in the following description, other numerical values and materials may be applied as long as the effects of the present invention can be obtained.

(Press machine)
The pressing device of the present invention is a device for press-forming a metal plate. The pressing device includes a die body, a pressing member, a first supporting mechanism, a punch, and a blank holder. The die body includes a first convex portion having a first plate pressing surface, and a concave portion adjacent to a shoulder portion of the first convex portion. Hereinafter, the recess of the die body may be referred to as a “recess (C1)”, and the shoulder (the shoulder of the first protrusion) adjacent to the recess (C1) may be referred to as a “shoulder (S1)”.

  The pressing member is arranged on the opposite side of the recess (C1) with the first plate pressing surface sandwiched therebetween. The pressing member includes a second plate pressing surface and has a shoulder portion on the side of the first plate pressing surface. Hereinafter, the shoulder portion (shoulder portion on the side of the first plate pressing surface) of the pressing member may be referred to as “shoulder portion (S2)”. The first support mechanism supports the pressing member and is capable of expanding and contracting in the pressing direction. The punch is disposed so as to face the die body in the pressing direction, and has a second convex portion corresponding to the concave portion (C1) of the die body. The blank holder is arranged to face both the first plate pressing surface and the second plate pressing surface in the pressing direction.

  In the pressing device of the present invention, the first support mechanism may be arranged between the die body and the pressing member. In that case, the first support mechanism may contract with the maximum pressing force of the die body.

  The pressing device of the present invention may include a second supporting mechanism that supports the blank holder so as to be movable in the pressing direction, and the first supporting mechanism may be arranged between the die body and the pressing member. In that case, the first supporting mechanism contracts with the maximum pressing force of the die body or the maximum pressing force of the second supporting mechanism. Here, the maximum pressing force means the maximum value of the pressing force applied in the press forming process.

  The pressing device of the present invention may include a control device that controls expansion and contraction of the first support mechanism. An example of the control device includes an arithmetic processing device and a storage device that stores a control program. A known control device may be applied to the control device. The control program is a program that controls the expansion and contraction of the first support mechanism according to the steps described below.

  The die and punch are used as a pair in press molding. That is, the die and punch have a shape for forming by sandwiching a metal plate between them. In this specification, the die and the punch can be read as the first die and the second die, respectively. In the pressing apparatus of the present invention, the die and the punch may be used as the upper die and the lower die, or may be used as the lower die and the upper die, respectively. The die, punch, and blank holder (wrinkle holder) are not particularly limited, and known ones may be applied.

  Below, the metal plate to be pressed may be referred to as a “blank”. When pressing the blank, a force from the blank is applied to the pressing member. The first support mechanism moves the pressing member while pressing the pressing member toward the blank holder (in other words, toward the blank). Similarly, a force from the blank is applied to the blank holder when the blank is pressed. The second support mechanism may move the blank holder while pressing the blank holder toward the pressing member (in other words, toward the blank).

  The first and second support mechanisms are not particularly limited as long as they can perform the above operations. The first and second support mechanisms may be mechanisms that expand and contract while applying a load to the pressing member and the blank holder, respectively. The first and second support mechanisms may be springs or pressure driven mechanisms (such as hydraulic mechanisms). The first support mechanism and the second support mechanism may be the same or different.

  The first support mechanism may be supported by the die body or may be supported by other than the die body. When the first support mechanism is supported by the die body, the die body may have a recess in which the pressing member is accommodated when the first support mechanism is contracted. Hereinafter, this recess may be referred to as a "recess (C2)". The first support mechanism may include a stop mechanism for stopping the pressing member at a predetermined position. For example, the first support mechanism may include a stopper for stopping the movement of the pressing member. Similarly, the second support mechanism may also include a stop mechanism (for example, a stopper) for stopping the blank holder at a predetermined position.

  The pressing member may be formed of the same material as the material forming the die. For example, the pressing member may be formed of steel used as a material for a press die.

  The pressing member is arranged apart from the shoulder portion (S1) of the first convex portion. The pressing member and the shoulder portion (S1) are arranged so as to sandwich the first plate pressing surface. Therefore, the two are separated by at least the first plate pressing surface.

  The distance L between the shoulder (S1) and the pressing member is not particularly limited as long as the effects of the present invention can be obtained. The distance L in one example may be 10 mm or more, and may be 50 mm or less. When the shoulder portion (S1) has a rounded shape (R shape), the distance L in one example may be two times or more the radius of curvature r of the R shape or may be ten times or less.

  In the pressing device of the present invention, when the second plate pressing surface projects most from the first plate pressing surface, the shoulder portion (S1) of the first convex portion and the shoulder portion (S2) of the pressing member are connected. The angle α formed by the line and the first plate pressing surface may be 15° or more. With this configuration, it is possible to particularly suppress the occurrence of defective molding in press molding. The angle α is less than 90°, and the upper limit thereof is not limited, but the configuration is simple if it is 75° or less. The angle α at which the second plate pressing surface contacts the blank at the start of molding may be in the range of 15° to 75° (for example, 30° to 60°). In addition, when the shoulder has a rounded shape (R shape), the position that becomes the shoulder assuming that there is no R shape is regarded as the position of the shoulder.

  In the pressing device of the present invention, the first plate pressing surface is moved so as to move at least between the position projecting from the first plate pressing surface and the position flush with the first plate pressing surface. It is preferable that the movable range of the support mechanism is secured. Here, “coplanar” means that the two surfaces are on the same plane.

  In the pressing device of the present invention, the ridgeline of the shoulder portion (S1) of the first convex portion may be convexly curved toward the concave portion (C1). According to this configuration, the portion of the blank sandwiched by the second plate pressing surface of the pressing member and the blank holder is stretch-flange-formed.

  When the ridgeline of the shoulder portion (S1) of the first convex portion is curved convexly toward the concave portion (C1) side, the normal line of the ridgeline and the normal line drawn on the first plate pressing surface It is preferable that there is a pressing member. At the time of molding, the blank flows toward the ridgeline of the shoulder portion (S1) in the direction normal to the ridgeline and is drawn in. Therefore, it is effective to dispose the pressing member so as to press the normal line of the ridge.

  In the pressing device of the present invention, the second plate pressing surface of the pressing member may be provided with irregularities for suppressing the blank displacement during press molding. For example, the linear concave portion arranged parallel to the shoulder portion (S2) of the pressing member and/or the linear convex portion arranged parallel to the shoulder portion (S2) of the pressing member has the second plate. It may be formed on the pressing surface. In this case, also on the surface of the blank holder facing the second plate pressing surface of the pressing member, the convex portion and/or the concave portion and/or the convex portion formed on the second plate pressing surface of the pressing member, and/or A recess may be formed.

  In addition, in the press apparatus of the present invention, the configuration not described in this specification is not particularly limited, and a known configuration may be applied.

(Method for manufacturing press-formed products)
The method of the present invention for producing a press-formed product will be described below. The production method of the present invention includes steps (i), (ii), and (iii) described below. In this manufacturing method, the pressing device of the present invention is used. From another viewpoint, this manufacturing method is a method for manufacturing a press-formed product using the above-mentioned molds (die body, pressing member, punch, blank holder, etc.). It should be noted that these molds have been described in other places, and thus redundant description may be omitted. The matters described below regarding the manufacturing method can be applied to the pressing apparatus and die of the present invention.

  In the step (i), the metal plate (blank) is sandwiched between the second plate pressing surface of the pressing member protruding from the first plate pressing surface of the first convex portion of the die body and the blank holder. In the step (i), the pressing member is supported by the first supporting mechanism such that the second plate pressing surface of the pressing member projects more than the first plate pressing surface of the die body. Therefore, the metal plate is first sandwiched between the pressing member and the blank holder. In a typical example, in step (i), a part of the outer edge of the metal plate is sandwiched between the pressing member and the blank holder.

  Examples of the metal plate include a metal plate called a thin steel plate, and include, for example, a high-tensile steel plate. Examples of the high-strength steel sheet include a steel sheet having a tensile strength of 440 MPa or more (for example, a range of 440 to 1500 MPa or a range of 980 to 1500 MPa).

  In the step (ii), the die body and the punch are brought close to each other with the second plate pressing surface still protruding from the first plate pressing surface, so that the shoulder portion (S1) of the first convex portion and the pressing member are pressed. Bend the metal plate at the shoulder (S2) of the.

  In the step (iii), a metal plate is formed by bringing the die body and the punch closer to each other and bringing the die body and/or the punch to a dead center while bringing the second plate pressing surface closer to the first plate pressing surface. .. A press-formed product is manufactured by the step (iii). Of course, the press-formed product obtained in step (iii) may be further pressed.

  To reach the dead center of the die body and/or the punch means to reach the dead center of at least one selected from the die body and the punch. This means that both the die body and the punch reach the position at the end of molding. If both the die body and the punch move during press forming, they reach the dead center. When only one of them moves during press molding, only one of them moves to the dead point. For example, when the upper die body moves, the die body reaches the bottom dead center. In another aspect, reaching the dead center of the die body and/or the punch can be replaced with reaching the position of the die body and the punch at the end of molding. When one of the die body and the punch does not move during molding, the one is in the position before press molding to the end of molding.

  In a preferable example in which the blank holder moves, the movement (retraction/storage) of the pressing member is started after the blank holder reaches the final position. It is also possible to start the movement (retraction/storage) of the pressing member before the blank holder reaches the final position.

  In the manufacturing method of the present invention, in the step (iii), the first plate pressing surface and the second plate pressing surface may be flush with each other when the die body and/or the punch reaches the dead center.

(Die)
The die of the present invention includes a die body, a pressing member, and a support mechanism (first support mechanism). The die body has a convex portion (first convex portion) having a first plate pressing surface and a concave portion (concave portion (C1)) adjacent to a shoulder portion (shoulder portion (S1)) of the first convex portion. Prepare The pressing member is arranged on the opposite side of the recess (C1) with the first plate pressing surface sandwiched therebetween. The pressing member includes a second plate pressing surface and has a shoulder (shoulder (S2)) on the side of the first plate pressing surface. The first support mechanism is arranged between the die body and the pressing member, supports the pressing member, and is expandable/contractible in the pressing direction. As described above, the die body may include the recess (C2) in which the pressing member is housed.

  Since the die main body, the pressing member, and the first support mechanism have been described above, duplicate description will be omitted. The die of the present invention can be used in combination with a pair of punches and blank holders.

  Examples of embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts may be denoted by the same reference numerals and redundant description may be omitted.

(First embodiment)
In the first embodiment, an example of a die including the die of the present invention will be described with reference to the drawings. A perspective view of the mold of the first embodiment is schematically shown in FIG. In order to facilitate understanding, only the shape of a part of the surface of the mold is schematically shown in FIG. The die main body 111 and the pressing member 112 shown in FIG. 1 are views when a part of their front surfaces is viewed from the back surface side. A cross section through line AA of FIG. 1 is schematically shown in FIG.

  The mold set 100 shown in FIG. 1 includes a die 110 that is an upper mold. As shown in FIG. 2, the die 110 includes a die body 111, a pressing member 112, and a first support mechanism 113 that supports the pressing member 112. The pressing member 112 is arranged so that it can be stored in the die body 111. The mold set 100 further includes a punch 121, a blank holder 122, and a second support mechanism 123 that supports the blank holder 122. These form the lower mold 120. The die 110 is supported by a holder on the upper die side of the pressing device. The lower die 120 is supported by a holder on the lower die side of the pressing device. In the mold set shown in FIG. 1, the die body 111 and the punch 121 can be brought close to each other by bringing the holder on the upper die side and the holder on the lower die side close to each other.

  The first support mechanism 113 supports the pressing member 112. The first support mechanism 113 is capable of expanding and contracting in the pressing direction, and can move the pressing member 112 backward (upward in FIG. 2) while pressing the pressing member 112 toward the blank holder 122 side (front). .. One end of the first support mechanism 113 supports the pressing member 112, and the other end is supported by the die body 111. Therefore, in the state where no force is externally applied to the pressing member 112, the pressing member 112 moves as the die body 111 moves.

  The second support mechanism 123 supports the blank holder 122 so as to be movable in the pressing direction. The second support mechanism 123 can move the blank holder 122 backward (downward in FIG. 2) while pressing the blank holder 122 toward the pressing member 112 side (upward in FIG. 2).

  With reference to FIG. 2, the die body 111 includes a convex portion 111a having an end surface that is a plate pressing surface (first plate pressing surface) 111p. The die body 111 further includes a recess 111b adjacent to the shoulder 111s of the protrusion 111a. The concave portion 111b becomes the concave portion 111b corresponding to the convex portion 121a of the punch 121. A recess 111c is formed on the opposite side of the recess 111b with the plate pressing surface 111p interposed therebetween. The recess 111c is a recess for housing the pressing member 112.

  The pressing member 112 is arranged on the opposite side of the recess 111b with the plate pressing surface 111p interposed therebetween. The pressing member 112 has a plate pressing surface (second plate pressing surface) 112p. Each of the plate pressing surface 111p and the plate pressing surface 112p is a surface (front end surface) that faces the blank before press molding, and is a surface that contacts the blank during press molding. The pressing member 112 has a shoulder 112s on the plate pressing surface 111p side.

  FIG. 2 shows a virtual plane P including the plate pressing surface 111p. In the state before press molding, the pressing member 112 is supported by the first support mechanism 113 so that the plate pressing surface 112p of the pressing member 112 projects beyond the plate pressing surface 111p (plane P) of the convex portion 111a. .. Of the side walls of the convex portion 111a, the side wall (vertical wall) on the concave portion 111b side may be referred to as a vertical wall 111w below. Further, among the side walls of the convex portion 121a of the punch 121, the side wall (vertical wall) on the convex portion 111a side may be referred to as a vertical wall 121w below.

  As shown in FIG. 2, the shoulder portion 111s of the convex portion 111a and the pressing member 112 are separated from each other. The distance L between the shoulder portion 111s and the pressing member 112 is preferably in the range described above.

  The angle α formed by the line connecting the shoulder portion 111s of the convex portion 111a and the shoulder portion 112s of the pressing member 112 and the plate pressing surface 111p is preferably in the range described above. When the shoulder has an R shape, the position where the shoulder exists assuming that there is no R shape is the position of the shoulder. Specifically, the position where the surface extending the vertical wall 111w and the plane including the plate pressing surface 111p intersect each other is the shoulder of the die body 111. Even when the shoulder 112s of the pressing member 112 has an R shape, the position of the shoulder is similarly determined.

  In a typical example, the pressing member 112 is arranged at a position corresponding to the outer edge of the metal plate to be formed. In one example of this case, the pressing member 112 is arranged at a part of the outer edge of the die body 111.

  The shape of the ridgeline of the shoulder portion 111s of the convex portion 111a in the vicinity of the line AA in FIG. 1 is schematically shown in FIG. In FIG. 3, the ridgeline of the shoulder of the protrusion 121a is also schematically shown. As shown in FIG. 3, the ridge line of the shoulder portion 111s of the convex portion 111a has a convex shape toward the concave portion 111b side (the convex portion 121a side). According to the shape shown in FIG. 3, the portion of the blank sandwiched by the plate pressing surface 112p of the pressing member 112 and the blank holder 122 can be stretch-flange formed. The cross section of the vertical wall 111w of the convex portion 111a, which is perpendicular to the pressing direction (the direction in which the mold moves), has a convex shape toward the concave portion 111b, similar to the ridge line of the shoulder portion 111s. Have. Further, the cross section of the vertical wall 121w of the convex portion 121a in the direction perpendicular to the pressing direction has a concave shape so as to correspond to the shape of the vertical wall 111w.

(Second embodiment)
In the second embodiment, an example of a method of performing press molding using the mold described in the first embodiment will be described with reference to FIGS. 4A to 4D. This method includes steps (i) to (iii) described above. Note that, in the following, description may be made using the reference numerals described in other drawings.

  First, as shown in FIG. 4A, a metal plate (blank) 201 to be press-molded is arranged between the die 110 and the lower mold 120. The second support mechanism 123 described in this embodiment includes an expansion/contraction mechanism 123a and a stopper 123b.

  Next, as shown in FIG. 4B, the metal plate 201 is sandwiched between the plate pressing surface 112p (pressing member 112) protruding from the plate pressing surface 111p (convex portion 111a) and the blank holder 122 (step (i)). .. In this embodiment, an example in which the upper die 110 moves is shown. In this case, the pressing member 112 also moves as the die body 111 moves.

  At the stage of step (i), the plate pressing surface 112p of the pressing member 112 is projected more than the plate pressing surface 111p of the convex portion 111a. That is, the plate pressing surface 112p is closer to the metal plate 201 than the plate pressing surface 111p. Therefore, the metal plate 201 is first sandwiched between the pressing member 112 and the blank holder 122. In a typical example, the end of the metal plate 201 is sandwiched between the plate pressing surface 112p of the pressing member 112 and the blank holder 122.

  In the next step (ii), as shown in FIG. 4C, the die body 111 and the punch 112 are brought close to each other with the plate pressing surface 112p still protruding from the plate pressing surface 111p. As a result, the metal plate 201 is bent at the shoulder portion 111s of the convex portion 111a and the shoulder portion 112s of the pressing member 112. Here, bringing the die main body 111 and the punch 112 closer to each other means bringing them closer to each other in the pressing direction. In other words, it means that the bottom of the concave portion 111b of the die body 111 and the convex portion 121a of the punch 121 are brought close to each other.

  In the next step (iii), as shown in FIG. 4D, the die body 111 and the punch 121 are brought closer to each other, and the plate pressing surface 112p is brought closer to the bottom dead center of the die body 111 while being brought closer to the first plate pressing surface 111p. .. FIG. 4D shows the time at the end of molding. In this embodiment, the case where only the upper mold moves is described. Therefore, the punch 112 does not move, and the die body 111 reaches the bottom dead center in FIG. 4D.

  At the stage of FIG. 4D, the movement of the blank holder 122 is stopped by the stopper 123b. In a typical example, at the end of molding (FIG. 4D), the plate pressing surface 112p of the pressing member 112 is flush with the plate pressing surface 111p of the convex portion 111a. That is, in a typical example, the plate pressing surface 112p of the pressing member 112 and the plate pressing surface 111p of the convex portion 111a are on the same plane at the timing when the positions of the die body 111 and the punch 112 are at the positions when the molding is completed. Is located in.

  In the stage of FIG. 4C, the metal plate 201 is bent at the position of the shoulder portion 111s of the die body 111 and the position of the shoulder portion 112s of the pressing member 112. At this time, the length of the metal plate 201 between the shoulder portion 111s of the die body 111 and the shoulder portion 112s of the pressing member 112 is longer than the distance L between the shoulder portion 111s and the pressing member 112. In order to bend the metal plate 201 at the position of the shoulder 112s of the pressing member 112, the plate pressing surface 112p of the pressing member 112 needs to be projected more than the plate pressing surface 111p of the convex portion 111a of the die body 111. Therefore, in the stage of FIG. 4C, the force by which the first support mechanism 113 pushes the pressing member 112 toward the blank holder 122 side is made larger than the force by which the second support mechanism 123 pushes the blank holder 122 toward the pressing member 112 side. .. More specifically, a stopper (not shown) limits the upper limit of the protrusion amount of the plate pressing surface 112p of the pressing member 112, and when the die body 111 moves toward the punch 121, the pressing member 112 is connected to the blank holder 122. The pressing force of the first supporting mechanism 113 is set to be larger than that of the second supporting mechanism 123 so that the pressing force of the second supporting mechanism 123 does not push the die body. Furthermore, the force with which the first support mechanism 113 presses the pressing member 112 is set so that the pressing member 112 is housed in the recess 111c of the die body 111 at the end of molding (when reaching the dead point). Specifically, the first support mechanism 113 is set so as to contract with the maximum pressing force of the die body 111. After the blank holder 122 comes into contact with the stopper 123b, the blank holder stops retreating and the first support mechanism 113 with a pressing force smaller than the pressing force of the die body 111 contracts, whereby the pressing member 112 moves toward the die body 111. (The protrusion amount of the pressing member 112 becomes small).

  In one example, the first support mechanism 113 and the second support mechanism 113 are set so that the pressing member 112 starts to be stored before the blank holder 122 reaches the final position (the position stopped by the stopper 123b in this embodiment). The spring constant and length of 123 may be adjusted. For example, in the process from the state of FIG. 4B to the state of FIG. 4D, the pressing member 112 may be gradually housed in the recess 111c of the die body 111. Alternatively, the storage of the pressing member 112 may be started after the blank holder 122 reaches the final position.

  The metal plate 201 is press-molded by the above steps (i) to (iii). When the die body 111 and the punch 121 having the shape shown in FIG. 3 are used, the metal plate 201 sandwiched between the die body 111 and the punch 121 is stretch-flange formed. FIG. 5 shows a perspective view of an example of a molded product that is press-molded using a mold similar to the mold shown in FIG. Region B of the press-formed product 210 in FIG. 5 is stretch-flange-formed.

  In the manufacturing method of the present invention, the metal plate 201 is bent at two places, the shoulder 112s of the pressing member 112 and the shoulder 111s of the die body 111. In the conventional bending and drawing, the metal plate is locally bent largely (for example, 90°) at the shoulder 111s of the die 111 and then drawn into the recess 111b of the die 111. In contrast to these, in the manufacturing method of the present invention, the deformation of the metal plate 201 is dispersed, and it is relieved that the metal plate 201 is locally largely bent at the shoulder 111s of the die 111. Further, the length of the metal plate 201 between the shoulder portion 111s of the die body 111 and the shoulder portion 112s of the pressing member 112 is longer than the distance L between the shoulder portion 111s and the pressing member 112. Therefore, when the pressing member 112 moves toward the die 111, the tensile strain applied to the metal plate 201 between the shoulder portion 111s of the die body 111 and the shoulder portion 112s of the pressing member 112 is relaxed. As a result, molding defects during press molding are suppressed. According to the present invention, it is possible to suppress cracks at the end portion 211 and the ridge line portion 212 (see FIG. 5) of the stretch flange, particularly when the stretch flange is formed. The pressing member 112 is also provided on the die 111 for forming the flange other than the region B in order to perform drawing on a portion other than the region B in FIG. Further, in order to adjust the inflow amount of the metal plate 201 from the region B and the other flanges so as to suppress the plate thickness variation, a bead may be provided on the plate pressing surface 112p of the pressing member 112.

Elongation flange forming was performed using the bending forming method described in FIGS. 8A to 8C, the drawing forming method described in FIGS. 9A to 9C, and the method of the present invention, and the reduction rate of the blank plate thickness was measured. The maximum value of the reduction rate of the plate thickness is shown in FIG. FIG. 6 shows the evaluation results at the end of the stretch flange and the ridge. The reduction rate (%) of the plate thickness is represented by the following formula, where T ₀ is the plate thickness before molding and T ₁ is the plate thickness after molding.
Reduction rate of plate thickness (%)=100×(T ₀ −T ₁ )/T ₀

  As shown in FIG. 6, in the manufacturing method of the present invention, the maximum value of the sheet thickness reduction rate was small at both the stretch flange end and the ridge. This indicates that cracking at those locations is suppressed.

(Third Embodiment)
In the first and second embodiments, the case where the convex portion and the pressing member are arranged only on one side of the concave portion (C1) of the punch has been illustrated. However, the protrusion and the pressing member may be arranged on both sides of the recess (C1) of the punch. A method for manufacturing a press-formed product using such a mold will be described with reference to FIGS. 7A to 7D. The manufacturing steps of FIGS. 7A to 7D are the same as the manufacturing steps of FIGS. 4A to 4D except that the configurations of the molds are different, and thus redundant description may be omitted.

  The die 200 shown in FIG. 7A includes a die 110a and a lower die 120a. The die 110a is the same as the die 110 except that it includes a die body 111 having two convex portions 111a, two pressing members 112, and two first supporting mechanisms 113, and thus a duplicate description will be omitted. A space between the two convex portions 111a becomes a concave portion 111b. The lower mold 120a is the same as the lower mold 120 except that it includes two blank holders 122 and two second support mechanisms 123, and thus redundant description will be omitted.

  In the manufacturing method of the third embodiment, first, as shown in FIG. 7A, the metal plate 201 is arranged between the die 110a and the lower die 120a. Next, as shown in FIG. 7B, the metal plate 201 is sandwiched between the pressing member 112 and the blank holder 122. Next, as shown in FIG. 7C, the metal plate 201 is bent by bringing the die body 111 having the two convex portions 111a and the punch 112 close to each other. Next, as shown in FIG. 7D, the die body 111 and the punch 112 are brought closer to each other to complete the molding. Through these steps, the metal plate 201 is formed. According to the manufacturing method of the third embodiment, the same effects as the effects described in the second embodiment can be obtained.

  In the above embodiment, the case where the recess for accommodating the pressing member is formed in the die body 111 has been described. However, such a recess may not be formed in the die body. In that case, one end of the first support mechanism may support the pressing member, and the other end may be supported by a portion other than the die body. Further, in the above embodiment, the case where the blank holder is supported by the second support mechanism has been described. However, the blank holder may be fixed. That is, the mold set may not include the second support mechanism. In an example of the step (iii) in that case, the die and the punch move together to perform press molding. For example, the punch is brought closer to the die to bend the metal plate, and then the die and the punch are brought closer to each other and the second plate pressing surface of the pressing member is brought close to the first plate pressing surface of the first convex portion. A metal plate may be formed.

  INDUSTRIAL APPLICABILITY The present invention can be used for a press device, a method for manufacturing a press-formed product using the press device, and a die. INDUSTRIAL APPLICABILITY The present invention is particularly preferably used for a press device, a method for manufacturing a press-formed product, and a die, which are related to stretch flange forming.

100 Mold set 110, 110a Die 111 Die body 111a First convex portion 111b Recessed portion (recessed portion (C1))
111c Recessed portion (recessed portion (C2))
111p plate pressing surface (first plate pressing surface)
111s shoulder (first convex shoulder)
111w, 121w Vertical wall 112 Pressing member 112p Plate pressing surface (second plate pressing surface)
112s Shoulder (shoulder of pressing member)
113 1st support mechanism 120,120a Lower mold 121 Punch 121a 2nd convex part 122 Blank holder 123 2nd support mechanism L Distance P Plane

Claims (9)

A die body including a first convex portion having a first plate pressing surface and a molding concave portion adjacent to a shoulder portion of the first convex portion;
A pressing member which is arranged on the opposite side of the concave portion with the first plate pressing surface sandwiched between the second plate pressing surface and a shoulder portion on the first plate pressing surface side;
A first support mechanism that supports the pressing member and is capable of expanding and contracting in the pressing direction;
A punch provided with a second convex portion corresponding to the concave portion, the punch being arranged so as to face the die body in the pressing direction;
See containing and a blank holder which is arranged to face the pressing direction with respect to both of the first blank holder surface and the second plate pressing surface,
The press device in which the ridgeline of the shoulder of the first convex portion is convexly curved toward the concave portion .   The press device according to claim 1, wherein the first support mechanism is disposed between the die body and the pressing member and contracts with a maximum pressing force of the die body. A second supporting mechanism for movably supporting the blank holder in the pressing direction,
The press according to claim 1, wherein the first support mechanism is arranged between the die body and the pressing member, and contracts with a maximum pressing force of the die body or a maximum pressing force of the second supporting mechanism. apparatus.   The press device according to claim 1, further comprising a control device that controls expansion and contraction of the first support mechanism.   The first plate and the line connecting the shoulder portion of the first convex portion and the shoulder portion of the pressing member when the second plate pressing surface projects most from the first plate pressing surface. The press device according to any one of claims 1 to 4, wherein an angle formed by the pressing surface is 15° or more.   The first support mechanism is configured such that the second plate pressing surface moves at least between a position projecting from the first plate pressing surface and a position flush with the first plate pressing surface. The press device according to any one of claims 1 to 5, wherein the movable range is secured. A linear concave portion arranged parallel to the shoulder portion of the pressing member and/or a linear convex portion arranged parallel to the shoulder portion of the pressing member is provided on the second plate pressing surface. is formed, the press apparatus according to any one of claims 1-6. Using a press device according to any one of claims 1 to 7 A method for producing a press-molded product,
(I) sandwiching a metal plate between the blank holder and the second plate pressing surface of the pressing member protruding from the first plate pressing surface of the first convex portion;
(Ii) There is a space between the concave portion of the die body and the second convex portion of the punch with the second plate pressing surface still protruding from the first plate pressing surface. In a state, by bringing the die body and the punch close to each other, bending the metal plate at the shoulder portion of the first convex portion and the shoulder portion of the pressing member,
(Iii) by bringing the die body and/or the punch closer to the die body and/or the die plate and/or the punch while bringing the second plate pressing surface closer to the first plate pressing surface. A method of manufacturing a press-formed product, which comprises a step of forming a plate. In the step of the (iii), the said first blank holder surface and the second blank holder face flush when the die body and / or the punch has reached the dead center to claim 8 The manufacturing method described.

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