JP2017136624A - Press apparatus, method for manufacturing pressed article using the same, and die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press apparatus that can reduce or eliminate failure in pressing.SOLUTION: The disclosed press apparatus includes: a die body 111; a pressing member 112; a first support mechanism 113; a punch 121; and a blank holder 122. The die body 111 includes: a first protrusion 111a having a first hold-down surface 111p; and a recess 111b adjacent to a shoulder portion 111s of the protrusion 111a. The pressing member 112 having a second hold-down surface 112p and a shoulder portion 112s is disposed opposite the recess 111b across the first hold-down surface 111p. The first support mechanism 113 supporting the pressing member 112 can extend and compress in a pressing direction. The punch 121 being opposed to the die body 111 in the pressing direction has a second protrusion 121a corresponding to the recess 111b. The blank holder 122 is opposed to both hold-down surfaces 111p, 112p in the pressing direction.SELECTED DRAWING: Figure 2

Description

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

  Various shapes of pressed products are manufactured by pressing a metal plate. Conventionally, it has been attempted to reduce the thickness of a pressed product by using a high-tensile steel plate, thereby reducing the weight of a pressed product. However, since a high-tensile steel sheet has low ductility, forming defects such as breakage and wrinkles are likely to occur when an article having a curved portion (such as a lower arm of an automobile) is press-formed. In particular, when an article having an elongated flange portion is press-molded, breakage tends to occur at the elongated 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 in the middle of molding, and FIG. 8C shows a final stage state of molding. In this bending, the metal plate 3 is bent and formed between the die 1 and the punch 2. In the bent metal plate 3, the deformation at the ridge 3a is small, but the elongation at the end 3b is large. For this reason, the bending at the end 3b of the metal plate 3 is likely to occur in bending.

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

  One method for preventing cracks in bending is disclosed in Japanese Patent Application Laid-Open No. 2015-1000081 (Patent Document 1). A part 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 recessed inward. The method of Patent Document 1 includes a step of pressing the blank material away from the R stop of the concave outer peripheral edge at a distance of 10 times to 100 times the plate thickness before processing the blank material, and bending the blank material in that state. Including the step of.

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

  It has been a conventional problem to further reduce the occurrence of defects in press molding. In particular, when a high-tensile steel plate is used, defects in press forming tend to occur. For example, when stretch flange molding is performed, cracks at the flange end portion and the ridge line portion are likely to occur. Therefore, there is a demand for a new method that can suppress the occurrence of molding defects in press molding.

Japanese Patent Laid-Open No. 2015-10082 JP-A-6-87039

  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 press device, and a die.

  A press apparatus according to an embodiment of the present invention includes a die main body including a first convex portion including a first plate pressing surface, and a concave portion adjacent to a shoulder portion of the first convex portion, and the first A pressing member that is disposed on the opposite side of the concave portion across the plate pressing surface, includes a second plate pressing surface, has a shoulder on the first plate pressing surface side, supports the pressing member, and presses A first support mechanism that can be expanded and contracted in a direction, a punch that is disposed so as to oppose the die body in the pressing direction, and includes a second convex portion corresponding to the concave portion, and the first plate pressing surface And a blank holder disposed so as to face both of the second plate pressing surfaces in the pressing direction.

The manufacturing method by one Embodiment of this invention is a manufacturing method of the press molded product using the press apparatus of this invention. This manufacturing method is
(I) a step of sandwiching a metal plate between the second plate pressing surface of the pressing member protruding from the first plate pressing surface of the first convex portion and the blank holder;
(Ii) The shoulder portion of the first convex portion and the pressing force by bringing the die body and the punch close to each other with the second plate pressing surface protruding from the first plate pressing surface. Bending the metal plate at the shoulder of the member;
(Iii) bringing the die body and / or the punch to the dead point while bringing the die body and the punch closer together and bringing the second plate pressing surface closer to the first plate pressing surface; Forming a plate.

  A die according to an embodiment of the present invention includes a die body including a convex portion including a first plate pressing surface, a concave portion adjacent to a shoulder portion of the convex portion, and the first plate pressing surface between the die body. Disposed on the opposite side of the recess, provided with a second plate pressing surface, a pressing member having a shoulder on the first plate pressing surface side, and disposed between the die body and the pressing member, And a supporting mechanism that supports the pressing member and can be expanded and contracted in the pressing direction.

  According to the present invention (press device, manufacturing method, and die), the occurrence of molding defects in press molding can be suppressed.

FIG. 1 is a perspective view schematically showing an example of a mold set including a 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 cross-sectional view schematically showing one 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 a process following FIG. 4A. FIG. 4C is a cross-sectional view schematically showing an example of a process following FIG. 4B. FIG. 4D is a cross-sectional view schematically showing an example of a process 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 molding by the conventional manufacturing method and the manufacturing method of the present invention. FIG. 7A is a cross-sectional view schematically showing one process of another example of the method of the present invention for producing a press-formed product. FIG. 7B is a cross-sectional view schematically showing an example of a process following FIG. 7A. FIG. 7C is a cross-sectional view schematically showing an example of a process following FIG. 7B. FIG. 7D is a cross-sectional view schematically showing an example of a process following FIG. 7C. FIG. 8A is a cross-sectional view schematically showing one step of an example of a conventional method for bending a stretch flange portion. FIG. 8B is a cross-sectional view schematically showing an example of a process following FIG. 8A. FIG. 8C is a cross-sectional view schematically showing an example of a process following FIG. 8B. FIG. 9A is a cross-sectional view schematically showing one step of an example of a conventional method for drawing a stretch flange portion. FIG. 9B is a cross-sectional view schematically showing an example of a process following FIG. 9A. FIG. 9C is a cross-sectional view schematically showing an example of a process following FIG. 9B.

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

(Press machine)
The press apparatus of this invention is an apparatus which press-forms a metal plate. The pressing device includes a die body, a pressing member, a first support 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 the shoulder portion of the first convex portion. Hereinafter, the concave portion of the die body may be referred to as “concave portion (C1)”, and the shoulder portion (shoulder portion of the first convex portion) adjacent to the concave portion (C1) may be referred to as “shoulder portion (S1)”.

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

  In the press device of the present invention, the first support mechanism may be disposed between the die body and the pressing member. In that case, the first support mechanism may be contracted by the maximum pressing force of the die body.

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

  The press 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 for controlling expansion and contraction of the first support mechanism in accordance with a process described later.

  A die and a punch are used as a pair for press molding. That is, the die and the punch have a shape for forming a metal plate between them. In this specification, the die and the punch can be read as the first mold and the second mold, respectively. In the press apparatus of the present invention, the die and punch may be used as an upper mold and a lower mold, respectively, or may be used as a lower mold and an upper mold. There is no particular limitation on the die, punch, and blank holder (wrinkle presser), and known ones may be applied.

  Hereinafter, the metal plate to be pressed may be referred to as “blank”. When the blank is press-molded, 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, when the blank is press-molded, a force from the blank is applied to the blank holder. 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 the above operation is possible. 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 drive 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 contracts. Hereinafter, this recess may be referred to as “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 that constituting the die. For example, the pressing member may be formed of a steel material used as a material for a press working mold.

  The pressing member is disposed away from the shoulder (S1) of the first convex portion. The pressing member and the shoulder (S1) are disposed so as to sandwich the first plate pressing surface. For this reason, the two are separated by at least the first plate pressing surface.

  As long as the effect of the present invention is obtained, there is no particular limitation on the distance L between the shoulder (S1) and the pressing member. An example distance L may be 10 mm or more, or 50 mm or less. When the shoulder portion (S1) has a rounded shape (R shape), an example distance L may be two times or more the radius of curvature r of the R shape and may be ten times or less.

  In the press device of the present invention, when the second plate pressing surface protrudes 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. According to this structure, generation | occurrence | production of the molding defect in press molding can be suppressed especially. The angle α is less than 90 °, and the upper limit is not limited, but the configuration is simple if it is 75 ° or less. The angle α when the second plate pressing surface comes into contact with the blank at the start of molding may be in the range of 15 ° to 75 ° (for example, in the range of 30 ° to 60 °). When the shoulder portion has a rounded shape (R shape), the position that becomes the shoulder portion when it is assumed that there is no R shape is regarded as the position of the shoulder portion.

  In the press device of the present invention, the first plate pressing surface is moved at least between a position protruding from the first plate pressing surface and a position flush with the first plate pressing surface. It is preferable that the movable range of the support mechanism is secured. Here, flush means that two planes exist on the same plane.

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

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

  In the press device of the present invention, the second plate pressing surface of the pressing member may be provided with irregularities for suppressing blank displacement during press molding. For example, the linear concave portion arranged in parallel with the shoulder portion (S2) of the pressing member and / or the linear convex portion arranged in parallel with the shoulder portion (S2) of the pressing member is 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, a convex portion and / or a fitting that fits into the concave portion and / or the convex portion formed on the second plate pressing surface of the pressing member. A recess may be formed.

  In addition, in the press apparatus of this invention, there is no limitation in particular about the structure which is not described in this specification, You may apply a well-known structure.

(Press-molded product manufacturing method)
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 press apparatus of the present invention is used. In another aspect, this manufacturing method is a method of manufacturing a press-formed product using the above-described molds (die body, pressing member, punch, blank holder, etc.). In addition, since these metal mold | dies are demonstrated in the other location, the overlapping description may be abbreviate | omitted. In addition, the matters described below for the manufacturing method can be applied to the press device and the 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 support mechanism such that the second plate pressing surface of the pressing member protrudes beyond 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 the 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, for example, a high-tensile steel plate. Examples of the high-tensile steel plate include a steel plate 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 shoulder portion (S1) of the first convex portion and the pressing member are brought close to each other by bringing the die body and the punch close to each other with the second plate pressing surface protruding from the first plate pressing surface. The metal plate is bent at the shoulder (S2).

  In step (iii), the metal plate is formed by bringing the die body and / or the punch to the dead point while bringing the die body and punch closer to each other and 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, you may further press-process the press-molded article obtained by process (iii).

  In other words, to make the die body and / or the punch reach the dead point is to make at least one selected from the die body and the punch reach the dead point. This means that both the die body and the punch reach the position at the end of molding. When both the die body and the punch move in press molding, both are made to reach the dead center. When only one of them moves in press molding, only one of them reaches the dead point. For example, when the die body that is the upper mold moves, the die body is made to reach the bottom dead center. In another aspect, it is possible to replace the die body and / or the punch reaching the dead point with the die body and the punch reaching the position at the end of molding. When either one of the die body and the punch does not move during molding, the one is in a position at the end of molding from before press molding.

  In a preferable example in the case where 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 moving (retracting / storing) 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 point.

(Die)
The die of the present invention includes a die body, a pressing member, and a support mechanism (first support mechanism). The die body includes a convex portion (first convex portion) having a first plate pressing surface and a concave portion (concave portion (C1)) adjacent to the shoulder portion (shoulder portion (S1)) of the first convex portion. Prepare. The pressing member is disposed on the side opposite to the concave portion (C1) across the first plate pressing surface. The pressing member includes a second plate pressing surface and has a shoulder portion (shoulder portion (S2)) on the first plate pressing surface side. The first support mechanism is disposed between the die body and the pressing member, supports the pressing member, and can be expanded and contracted in the pressing direction. As described above, the die body may include a recess (C2) in which the pressing member is accommodated.

  Since the die main body, the pressing member, and the first support mechanism have been described above, overlapping descriptions are omitted. The die of the present invention can be used in combination with a pair of punch and blank holder.

  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 overlapping description may be omitted.

(First embodiment)
1st Embodiment demonstrates an example of the metal mold | die containing the die | dye of this invention, referring drawings. The perspective view of the metal mold | die of 1st Embodiment is typically shown in FIG. For ease of understanding, FIG. 1 schematically shows only a part of the shape of the mold surface. The die main body 111 and the pressing member 112 shown in FIG. 1 are views when a part of their surfaces is viewed from the back side. A cross-section passing through line AA in FIG. 1 is schematically shown in FIG.

  A 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 disposed so as to be housed 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 constitute the lower mold 120. The die 110 is supported by a holder on the upper die side of the press device. The lower mold 120 is supported by a holder on the lower mold side of the press device. In the mold set shown in FIG. 1, the die body 111 and the punch 121 can be brought closer by bringing the upper mold side holder and the lower mold side holder closer to each other.

  The first support mechanism 113 supports the pressing member 112. The first support mechanism 113 can expand and contract in the pressing direction, and can move the pressing member 112 rearward (upward in FIG. 2) while pressing the pressing member 112 toward the blank holder 122 (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 a state where no force is applied to the pressing member 112 from the outside, 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 (upward in FIG. 2).

  Referring to FIG. 2, the die body 111 includes a convex portion 111 a whose end surface is a plate pressing surface (first plate pressing surface) 111 p. The die body 111 further includes a recess 111b adjacent to the shoulder 111s of the protrusion 111a. The recess 111 b becomes a recess 111 b corresponding to the protrusion 121 a of the punch 121. A recess 111c is formed on the side opposite to the recess 111b across the plate pressing surface 111p. The recess 111 c is a recess for accommodating the pressing member 112.

  The pressing member 112 is disposed on the opposite side to the concave portion 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 (tip 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 portion 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 protrudes from 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, the side wall (vertical wall) on the convex portion 111a side among the side walls of the convex portion 121a of the punch 121 may be hereinafter referred to as a vertical wall 121w.

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

  The angle α formed by the line connecting the shoulder 111s of the convex portion 111a and the shoulder 112s of the pressing member 112 and the plate pressing surface 111p is preferably in the above-described range. When the shoulder portion has an R shape, the position where the shoulder portion exists is assumed to be the position of the shoulder portion when it is assumed that there is no R shape. Specifically, a position where the plane extending from the vertical wall 111w and the plane including the plate pressing surface 111p intersect is defined as the shoulder portion 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 determined in the same manner.

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

  FIG. 3 schematically shows the shape of the ridge line of the shoulder portion 111s of the convex portion 111a in the vicinity of the line AA in FIG. In FIG. 3, the ridgeline of the shoulder part of the convex part 121a is also shown schematically. As shown in FIG. 3, the ridge line of the shoulder 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 sandwiched between the plate pressing surface 112 p of the pressing member 112 and the blank holder 122 in the blank can be stretched and flange-formed. Note that the cross section of the vertical wall 111w of the convex portion 111a in the direction perpendicular to the pressing direction (the direction in which the mold moves) has a convex shape toward the concave portion 111b as in the ridgeline of the shoulder portion 111s. Have. Moreover, the cross section of the vertical wall 121w of the convex part 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 the steps (i) to (iii) described above. In addition, below, it may demonstrate using the code | symbol demonstrated in another drawing.

  First, as shown in FIG. 4A, a metal plate (blank) 201 to be press-molded is disposed 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 moves with the movement of the die body 111.

  In the step (i), the plate pressing surface 112p of the pressing member 112 protrudes from the plate pressing surface 111p of the convex portion 111a. That is, the plate pressing surface 112p is present 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 112 p 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 protruding from the plate pressing surface 111p. As a result, the metal plate 201 is bent at the shoulder 111s of the convex portion 111a and the shoulder 112s of the pressing member 112. Here, bringing the die body 111 and the punch 112 closer means that they are closer to the press direction. In other words, it means that the bottom of the concave portion 111 b of the die body 111 and the convex portion 121 a 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 close to the first plate pressing surface 111p to reach the bottom dead center of the die body 111. . FIG. 4D shows a time point 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.

  In 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 become the positions at the end of molding. Placed in.

  4C, the metal plate 201 is bent at the position of the shoulder 111s of the die body 111 and the position of the shoulder 112s of the pressing member 112. At this time, the length of the metal plate 201 between the shoulder 111s of the die body 111 and the shoulder 112s of the pressing member 112 is longer than the distance L between the shoulder 111s and the pressing member 112. In order to bend the metal plate 201 at the position of the shoulder 112 s of the pressing member 112, the plate pressing surface 112 p of the pressing member 112 needs to protrude from the plate pressing surface 111 p of the convex portion 111 a 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 is made larger than the force by which the second support mechanism 123 pushes the blank holder 122 toward the pressing member 112. . More specifically, the upper limit of the protruding amount of the plate pressing surface 112 p of the pressing member 112 is limited by a stopper (not shown), and the pressing member 112 is connected to the blank holder 122 when the die body 111 moves toward the punch 121. The pressing force of the first support mechanism 113 is set larger than that of the second support mechanism 123 so that the pressing force of the second support mechanism 123 is not pushed toward the die body. Furthermore, the force with which the first support mechanism 113 pushes the pressing member 112 is set so that the pressing member 112 is housed in the concave portion 111 c of the die body 111 at the end of molding (when the dead center is reached). 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 backward movement is stopped, and the first support mechanism 113 having a pressing force smaller than the pressing force of the die body 111 contracts, so that the pressing member 112 moves toward the die body 111. (The protruding amount of the pressing member 112 is reduced).

  In one example, the first support mechanism 113 and the second support mechanism are configured so that the pressing member 112 starts to be stored before the blank holder 122 reaches the final position (the position where the blank holder 122 is 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-formed 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 stretched and 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 stretched flange-molded.

  In the manufacturing method of the present invention, the metal plate 201 is bent at two places, the shoulder 112 s of the pressing member 112 and the shoulder 111 s of the die body 111. In the conventional bending molding or drawing molding, the metal plate is locally bent large (for example, 90 °) by the shoulder 111 s of the die 111 and then drawn into the concave portion 111 b of the die 111. Unlike them, in the manufacturing method of the present invention, the deformation of the metal plate 201 is dispersed, and the metal plate 201 is moderately bent greatly at the shoulder 111s of the die 111. Furthermore, the length of the metal plate 201 between the shoulder 111s of the die body 111 and the shoulder 112s of the pressing member 112 is longer than the distance L between the shoulder 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 relieved. As a result, molding defects during press molding are suppressed. According to the present invention, in particular, when stretch flange molding is performed, cracks at the end portion 211 and the ridgeline portion 212 (see FIG. 5) of the stretch flange can be suppressed. The pressing member 112 is also provided in the die 111 for forming a flange other than the region B in order to draw the portion other than the region B in FIG. In addition, a bead may be provided on the plate pressing surface 112p of the pressing member 112 in order to adjust the inflow amount of the metal plate 201 from the region B and other flanges so as to suppress variation in plate thickness.

Stretch flange forming was performed using the bending method described in FIGS. 8A to 8C, the drawing 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 plate thickness reduction rate is shown in FIG. In FIG. 6, the evaluation result in an extending flange edge part and a ridgeline part is shown. The reduction rate (%) of the plate thickness is expressed by the following equation when the plate thickness before molding is T ₀ and the plate thickness after molding is T ₁ .
Sheet thickness reduction rate (%) = 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 plate thickness reduction rate was small at both the end portion of the stretch flange and the ridge line portion. This indicates that cracking at those locations is suppressed.

(Third embodiment)
In 1st and 2nd embodiment, it illustrated about the case where a convex part and a press member are arrange | positioned only at the one side of the recessed part (C1) of a punch. However, convex portions and pressing members may be disposed on both sides of the concave portion (C1) of the punch. A method for producing a press-formed product using such a mold will be described with reference to FIGS. 7A to 7D. Except for the difference in the configuration of the mold, the manufacturing steps of FIGS. 7A to 7D are the same as the manufacturing steps of FIGS. 4A to 4D, respectively, and therefore redundant description may be omitted.

  A mold 200 shown in FIG. 7A includes a die 110a and a lower mold 120a. The die 110a is the same as the die 110 except that the die 110a includes the die main body 111, the two pressing members 112, and the two first support mechanisms 113 each having two convex portions 111a. A recess 111b is formed between the two protrusions 111a. The lower mold 120a is the same as the lower mold 120 except that the lower mold 120a includes two blank holders 122 and two second support mechanisms 123, and thus redundant description is omitted.

  In the manufacturing method of the third embodiment, first, as shown in FIG. 7A, a metal plate 201 is disposed between the die 110a and the lower mold 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 closer to each other. Next, as shown in FIG. 7D, the die body 111 and the punch 112 are brought closer together 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 those described in the second embodiment can be obtained.

  In the above embodiment, the case where the concave portion 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. Moreover, said embodiment demonstrated the case where the blank holder was supported by the 2nd support mechanism. 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 close to the die to bend the metal plate, and then the die and the punch are brought closer together 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 producing a press-molded product using the press device, and a die. The present invention is particularly preferably used for a press apparatus, a method for producing a press-formed product, and a die related to stretch flange molding.

100 Die set 110, 110a Die 111 Die body 111a First protrusion 111b Recess (recess (C1))
111c recess (recess (C2))
111p board holding surface (first board holding surface)
111s shoulder (shoulder of the first convex part)
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 | type 121 Punch 121a 2nd convex part 122 Blank holder 123 2nd support mechanism L Distance P Plane

Claims (14)

A die main body including a first convex portion including a first plate pressing surface, and a concave portion adjacent to a shoulder portion of the first convex portion;
A pressing member disposed on the opposite side of the concave portion across the first plate pressing surface, provided with a second plate pressing surface, and having a shoulder on the first plate pressing surface side;
A first support mechanism that supports the pressing member and can be expanded and contracted in a pressing direction;
A punch that is disposed so as to face the die body in the pressing direction and includes a second convex portion corresponding to the concave portion;
And a blank holder disposed so as to face both the first plate pressing surface and the second plate pressing surface in the pressing direction.   The press apparatus 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 support mechanism for supporting the blank holder so as to be movable in the press direction;
2. The press according to claim 1, wherein the first support mechanism is disposed between the die body and the pressing member and contracts by a maximum pressing force of the die body or a maximum pressing force of the second support mechanism. apparatus.   The press device according to claim 1, comprising a control device that controls expansion and contraction of the first support mechanism.   When the second plate pressing surface protrudes most from the first plate pressing surface, a line connecting the shoulder portion of the first convex portion and the shoulder portion of the pressing member and the first plate 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 so that the second plate pressing surface moves at least between a position protruding 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 a movable range is secured.   The press device according to any one of claims 1 to 6, wherein a ridge line of the shoulder portion of the first convex portion is convexly curved toward the concave portion side.   A linear concave portion arranged in parallel with the shoulder portion of the pressing member and / or a linear convex portion arranged in parallel with the shoulder portion of the pressing member are formed on the second plate pressing surface. The press apparatus of any one of Claims 1-7 currently formed. A method for producing a press-formed product using the press device according to any one of claims 1 to 8,
(I) a step of sandwiching a metal plate between the second plate pressing surface of the pressing member protruding from the first plate pressing surface of the first convex portion and the blank holder;
(Ii) The shoulder portion of the first convex portion and the pressing force by bringing the die body and the punch close to each other with the second plate pressing surface protruding from the first plate pressing surface. Bending the metal plate at the shoulder of the member;
(Iii) bringing the die body and / or the punch to the dead point while bringing the die body and the punch closer together and bringing the second plate pressing surface closer to the first plate pressing surface; And a step of forming a plate.   In the step (iii), when the die body and / or the punch reaches a dead center, the first plate pressing surface and the second plate pressing surface are flush with each other. The manufacturing method as described. A die body including a convex portion provided with a first plate pressing surface and a concave portion adjacent to a shoulder portion of the convex portion;
A pressing member disposed on the opposite side of the concave portion across the first plate pressing surface, provided with a second plate pressing surface, and having a shoulder on the first plate pressing surface side;
A die including a support mechanism disposed between the die body and the pressing member to support the pressing member and extend and contract in a pressing direction.   The movable range of the support mechanism is such that the second plate pressing surface moves at least between a position protruding from the first plate pressing surface and a position flush with the first plate pressing surface. The die according to claim 11, wherein   When the second plate pressing surface protrudes most from the first plate pressing surface, a line connecting the shoulder portion of the convex portion and the shoulder portion of the pressing member, and the first plate pressing surface The die according to claim 11 or 12, wherein an angle formed by is 15 ° or more. The die according to any one of claims 11 to 13, wherein a ridge line of the shoulder portion of the convex portion is convexly curved toward the concave portion side.

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