JP6658465B2 - Press forming mold and press forming method - Google Patents

Description

  The present invention relates to a press-molding die and a press-forming method, and more particularly to a press-molding die and a press-forming method for a press-formed product subjected to press-forming under shrinkage flange deformation.

When press-forming a press-formed product having a vertical wall portion in which a bending ridge is curved and shrinks to form a flange, the vertical wall portion is formed by being subjected to in-plane compression deformation, and the amount of compression deformation is away from the bending ridge. It becomes bigger. For example, in the case where a top plate portion is press-molded into a convexly curved part, if the ridgeline between the top plate portion and the vertical wall portion is curved, the compression deformation of the vertical wall portion increases as the distance from the top plate portion increases.
Then, there is a problem that wrinkles are generated in the vertical wall portion of the press-formed product subjected to such compressive deformation, and in particular, when high-tensile steel sheet is used, the generation of wrinkles becomes remarkable. The shape defect of the press-formed product becomes a problem. Therefore, it is necessary to take measures to suppress the generation of wrinkles due to the compressive deformation in the vertical wall surface during the forming process.

2. Description of the Related Art Conventionally, it has been generally practiced to suppress generation of wrinkles by forming a concavo-convex portion in a vertical wall portion from an in-plane to a plate end portion (Non-Patent Document 1).
Further, in Patent Document 1, in a press-formed body having a vertical wall surface having a curvature and a flange surface below the vertical wall surface, a convex bead stuck to the vertical wall surface in a convex shape is provided, and the convex shape is formed. A pressing method for suppressing wrinkling by providing a concave bead formed in a concave shape on a flange surface immediately below the bead is disclosed.
Further, in Patent Document 2, in the molding of a metal product having a U-shaped or C-shaped cross section, at a position corresponding to a convex curved portion in the longitudinal direction of the vertical wall portion of the product, A multi-stage press forming method for providing a convex emboss is disclosed.

JP 2010-115674 A JP 2008-12570A

Edited by Thin Steel Sheet Forming Technology Study Group, “Handbook for Press Forming Difficulty”, Third Edition, Nikkan Kogyo Shimbun, April 2007, p.283-284

  Non Patent Literature 1 and Patent Literature 1 disclose a technique for forming the above-mentioned convex bead on a curved vertical wall portion, but a press-formed product having such a vertical wall portion has a U-shaped cross section. When welding with other parts with a shape, the seating surface of the convex bead may be used as a joining surface, in such a case, avoid wrinkling on the seating surface of the convex bead Therefore, it is required to absorb a surplus of wrinkling material and to form the convexity of the convex bead with high flatness.

  However, according to the technique disclosed in Patent Literature 1, when a mold having a bending blade (die) having a concave portion along the shape of the convex bead of the punch is used, the bending blade is not formed during the molding. The blank is bent and deformed into the shape of a convex bead at the concave portion, and at the bottom dead center of the molding, the seat surface of the convex bead is crushed flat, but the convex bead has a bending habit and the press molded product is removed from the mold. Since there is a problem that the seat surface is wrinkled due to elastic recovery at the time of taking out or cannot be completely crushed, the surface accuracy becomes poor and the flatness of the seat surface of the convex bead is reduced.

  In addition, the technology disclosed in Patent Literature 2 is to provide a convex embossment at a position corresponding to a curved portion with respect to a vertical wall portion curved in a convex shape in a longitudinal direction, so that a line length difference between material end portions is provided. It is intended to eliminate wrinkles and eliminate wrinkles.However, there is no disclosure or suggestion about flattening the seating surface of the convex embossment, and the technology disclosed in Patent Document 1 Similarly, there is a problem that wrinkles generated on the seating surface of the convex emboss cannot be suppressed to form a high flatness.

  The present invention has been made in order to solve the above-described problems, and has a vertical wall portion in which a top plate portion is curved and is continuously formed from the top plate portion and contracts to form a flange, When molding a press-formed product having a flat bearing surface on the vertical wall portion and a convex portion extending in the height direction of the vertical wall portion, it is possible to suppress wrinkles from being generated on the seat surface of the convex portion. Accordingly, it is an object of the present invention to provide a press-forming die and a press-forming method capable of forming the seat surface with high flatness.

(1) The press-molding die according to the present invention has a vertical wall portion in which a top plate portion is curved and is continuously formed from the top plate portion to be shrunk and flange deformed. The convex portion extending in the height direction of the vertical wall portion is for forming a press-formed product formed on the vertical wall portion, and has a punch and a die, and the punch forms the vertical wall portion. A punch-side vertical wall forming surface portion, wherein the punch-side vertical wall forming surface portion is formed with a convex-shaped forming portion having a flat seating surface and extending in a height direction; and the die includes the punch-side vertical wall forming surface portion. A die-side vertical wall forming surface portion for forming the vertical wall portion in cooperation with the die-side vertical wall forming surface portion is provided continuously from the die-side vertical wall forming surface portion, and all or a part thereof is provided before the die-side vertical wall forming surface portion. Has a wavy deformation suppressing surface portion that abuts on the blank to suppress wavy deformation of the blank, The side vertical wall forming surface portion has a concave portion formed at a portion corresponding to the convex shape forming portion formed on the punch side vertical wall forming surface portion, and the wavy deformation suppressing surface portion is formed of the die side vertical wall forming surface portion. It has a blank contact surface portion wider than the concave portion.

(2) In the device described in the above (1), the blank contact surface portion of the wavy deformation suppressing surface portion extends over the entire length in the longitudinal direction of the die.

(3) The press forming method according to the present invention has a vertical wall portion in which a top plate portion is curved and is continuously formed from the top plate portion and contracts to form a flange. A press-formed product in which a convex portion extending in the height direction of the portion is formed on the vertical wall portion by using the press-molding die according to the above (1) or (2), A vertical wall forming step of forming a vertical wall portion by placing a blank on the punch and moving the punch and the die relative to each other, wherein the vertical wall forming step includes a step of forming the vertical wall portion of the wavy deformation suppressing surface portion; A first bending forming step of relatively moving the die toward the punch with a contact surface portion in contact with the blank, and then forming the die with the wavy deformation suppressing surface separated from the blank; And a second bending step of relatively moving to a point. It is intended to.

(4) The press forming method according to the present invention is characterized in that the top plate portion has a curved vertical wall portion which is continuously formed from the top plate portion to be shrunk and flange deformed. A press-formed product in which a convex portion extending in the height direction of the portion is formed on the vertical wall portion by using the press-molding die according to the above (1) or (2), A grooved blank forming step of forming a grooved blank in which a plurality of groove-shaped portions extending in a direction corresponding to the height direction of the vertical wall portion are formed at predetermined intervals in a portion corresponding to the vertical wall portion in the blank; The grooved blank is placed on the punch, and the punch and the die are relatively moved to bend the vertical wall portion where the convex portion is formed between the plurality of formed groove portions. Vertical wall forming step, the vertical wall forming step is at least the wavy A first bending step of relatively moving the die to the punch side in a state where the blank contact surface portion of the shape suppressing surface portion is in contact with the grooved blank, and thereafter, the wavy deformation suppressing surface portion has the grooved blank. A second bending step of relatively moving the die to the bottom dead center of the molding while away from the mold.

  The press-molding die of the present invention has a punch and a die, and the punch has a punch-side vertical wall forming surface for forming the vertical wall, and the punch-side vertical wall forming surface has a seating surface. A flat-shaped convex portion extending in the height direction is formed, the die includes a die-side vertical wall forming surface portion for forming the vertical wall portion in cooperation with the punch-side vertical wall forming surface portion; Wavy deformation suppression which is provided continuously from the side vertical wall forming surface portion and suppresses all or a part of the die from contacting with the blank prior to the die-side vertical wall forming surface portion to prevent wavy deformation of the blank. A surface portion, wherein the die-side vertical wall forming surface portion has a concave portion formed at a portion corresponding to the convex shape forming portion formed on the punch-side vertical wall forming surface portion, and the wavy deformation suppressing surface portion is Be sure to have a blank contact surface that is wider than the recess on the die side vertical wall molding surface. Thereby, by suppressing bending deformation of a portion corresponding to the convex portion in the blank in the forming process, it is possible to suppress wrinkles from being generated on the seat surface of the convex portion, and to flatten the seat surface of the convex portion. A highly press-formed product can be obtained.

FIG. 3 is an explanatory diagram illustrating a press-molding mold according to Embodiment 1 of the present invention. FIG. 5 is an explanatory diagram illustrating a press-formed product to be formed in Embodiments 1 to 4 of the present invention. FIG. 5 is an explanatory view illustrating a conventional press-molding die for forming a press-formed product to be molded in Embodiments 1 to 4 of the present invention. FIG. 9 is a diagram showing an analysis result of a deformation behavior of a blank in a process of forming a press-formed product using a conventional press-forming die. FIG. 4 is a diagram showing an analysis result of a deformation behavior of a blank in a process of forming a press-formed product using the press-molding die according to Embodiment 1 of the present invention. FIG. 5 is an explanatory diagram illustrating a press-molding mold according to Embodiment 2 of the present invention. FIG. 9 is a diagram showing an analysis result of a deformation behavior of a blank in a process of forming a press-formed product using the press-molding die according to Embodiment 2 of the present invention. In the press forming method according to Embodiment 3 of the present invention, a step (a) of forming a grooved blank having a downwardly convex groove-shaped portion formed therein, and a press-formed product is formed using the formed grooved blank. It is explanatory drawing explaining a process (b). It is a figure which shows the press-molded article which concerns on Embodiment 3 and 4 of this invention, and the shape of the grooved blank in which the downward convex groove shape part was shape | molded. It is a figure which shows the analysis result of the deformation | transformation behavior of the grooved blank in which the downward convex groove shape part was formed in the process of shape | molding a press-formed product by the press-forming method which concerns on Embodiment 3 of this invention. In the press-forming method according to Embodiment 3 of the present invention, a step (a) of forming a grooved blank having an upwardly convex groove-shaped portion, and a press-formed product is formed using the formed grooved blank. It is explanatory drawing explaining a process (b). It is a figure which shows the analysis result of the deformation | transformation behavior of the grooved blank in which the upper convex-groove-shaped part was formed in the process of shape | molding a press molded article by the press molding method concerning Embodiment 3 of this invention. In the press forming method according to Embodiment 4 of the present invention, a step (a) of forming a grooved blank having a downwardly convex groove-shaped portion, and a press-formed product is formed using the formed grooved blank. It is explanatory drawing explaining a process (b). It is a figure which shows the analysis result of the deformation | transformation behavior of the grooved blank in which the downward convex groove shape part was formed in the process of shape | molding a press-formed product by the press-forming method concerning Embodiment 4 of this invention. In the press-forming method according to Embodiment 4 of the present invention, a step (a) of forming a grooved blank having an upwardly convex groove-shaped portion, and a press-formed product is formed using the formed grooved blank. It is explanatory drawing explaining a process (b). It is a figure which shows the analysis result of the deformation | transformation behavior of the grooved blank in which the upward convex groove-shaped part was formed in the process of shape | molding a press-formed product by the press-forming method concerning Embodiment 4 of this invention. FIG. 4 is an explanatory diagram illustrating evaluation items for evaluating the occurrence of wrinkles on a seat surface and a ridgeline portion of a convex-shaped portion of a press-formed product in an example of the present invention. 5 is a graph showing an analysis result of a change in a radius of curvature in a forming process of a portion corresponding to a lower end of a convex portion of a press-formed product formed by a conventional press-molding die in the present example. FIG. 6 is a diagram of an analysis result showing an influence of a vertical wall forming height on wrinkling occurrence on a bearing surface of a convex-shaped portion of a press-formed product formed by a conventional press forming die in the present example. FIG. 9 is a diagram of an analysis result showing an influence of a seat height of a convex portion on a wrinkle generation on a seat surface of the convex portion of a press-formed product formed by a conventional press-molding die in the present example. In this example, it is a figure which shows the evaluation result of the wrinkling generation in the bearing surface and the ridge line part of the convex part of the press-formed product shape | molded by the press molding die which concerns on this invention as an invention example (invention examples 1 thru | or 3). ). In this example, it is a figure which shows the evaluation result of the wrinkle generation | occurrence | production in the bearing surface and the ridgeline part of the convex-shaped part of the press-molded article shape | molded by the press molding die which concerns on this invention as an invention example (invention examples 4 and 5). ). In this example, it is a figure which shows the evaluation result of the wrinkle generation in the bearing surface and the ridge line part of the convex-shaped part of the press-molded article shape | molded by the press molding die which concerns on this invention as an invention example (invention examples 6 and 7). ).

Prior to describing the press-molding die and the press-forming method according to Embodiments 1 to 4 of the present invention, a press-formed product 1 to be formed in the present invention will be described.
In the specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.

[Press molding]
In the press-formed product 1 to be formed in the embodiment of the present invention, as shown in FIG. 2, the top plate portion 3 is curved upwardly convexly in a side view along the longitudinal direction of the press-formed product 1, The U-shaped section has a vertical wall portion 5 which is continuously formed from the top plate portion 3 via the ridge line portion 4 to be shrunk and flange-deformed, in which the seating surface 9 is flat and vertical. A convex portion 7 extending in the height direction from the lower end of the wall portion 5 is formed.

Conventionally, the press-formed product 1 cooperates with a punch 13 having a punch-side vertical wall forming surface portion 19 for forming the vertical wall portion 5 and a punch-side vertical wall forming surface portion 19, as shown in FIG. Using a die 15 having a die-side vertical wall forming surface portion 21 for forming the vertical wall portion 5 by pressing, and a pad 17 for holding a portion of the blank 31 corresponding to the top plate portion 3. In order to form the convex portion 7 on the vertical wall portion 5, a convex shape forming portion 25 is formed on the punch side vertical wall forming surface portion 19, and the die side vertical wall forming surface portion 21 corresponds to the convex shape forming portion 25. A concave portion 27 is formed at the portion where the light beam flows.
Note that the press-molding die 11 and the press-formed product 1 shown in FIG. 3 show only a half portion in the width direction.

  The convex-shaped portion 7 of the press-formed product 1 is formed on the vertical wall portion 5 in order to suppress the generation of wrinkles in the vertical wall portion 5 due to shrinkage flange deformation in the forming process. When joining the to the other part, it is necessary to form the seating surface 9 flat in order to make the seating surface 9 of the convex part 7 a joining surface with the other part. However, when the press-formed product 1 is formed using the press-forming mold 11, wrinkles are generated on the seating surface 9 of the convex portion 7 and the flatness is deteriorated, which is a problem when joining with other parts. There was a case.

  Here, the reason why wrinkles are generated on the seating surface 9 of the convex portion 7 is analyzed by press-forming analysis in the process of forming the press-formed product 1 using the press-forming die 11 shown in FIG. This will be described below based on the analysis result of the deformation behavior of the blank 31 in the forming process shown in FIG. In FIG. 4, the punch 13, the pad 17, and the blank 31 are illustrated without displaying the die 15 (see FIG. 3) so that the deformation of the blank 31 is easily seen.

  When the press-formed product 1 is press-formed using the press-forming die 11, when the die 15 is relatively moved toward the punch 13 with the upper surface of the blank 31 being pressed by the pad 17, the bending blade R of the die 15 The portion 23 (see FIG. 3A) comes into contact with the surface of the blank 31.

  Here, on the die-side vertical wall forming surface portion 21, a concave portion 27 forming the convex portion 7 on the vertical wall portion 5 and a convex portion 29 protruding toward the punch 13 between the concave portions 27 are formed. The surface of the die-side vertical wall forming surface portion 21 has an uneven shape, and the uneven shape continues to the bending blade R portion 23 (see FIG. 3A).

  Therefore, when the bending blade R portion 23 of the die 15 comes into contact with the surface of the blank 31, first, the convex portion 29 of the bending blade R portion 23 is formed on the surface of the blank 31 with the adjacent convex portion 7 of the press-formed product 1. The gap is abutted as a part to be formed.

  When the die 15 is further moved to the punch 13 side, even if the convex portion 29 of the bending blade R portion abuts on the surface of the blank 31 and starts forming, the concave portion 27 does not abut. Is deformed in a wave-like shape due to plastic bending (FIG. 4 (d-2)).

Such a wavy deformation of the blank 31 is deformed into a gently uneven shape near the bottom dead center of the molding (FIG. 4E) by the concave portion 27 of the die 15 and the convex shape forming portion 25 of the punch 13. Even if the part that has undergone plastic bending is pressed firmly flat, the bending habit remains without completely eliminating the plastic bending deformation, and as a result, the bottom dead center of the molding (FIG. 4 (f)) In this case, wrinkles are formed on the seating surface 9 of the convex portion 7 and it becomes difficult to form the flat portion flat.
Furthermore, the flatness of a portion where a bending habit remains due to plastic bending deformation decreases as the radius of curvature of the bending decreases, and this tendency is particularly remarkable in a high-tensile steel sheet.

  The present invention is generated on the seating surface 9 of the convex portion 7 of the press-formed product 1 by suppressing the wavy deformation generated in the blank 31 in the process of forming the vertical wall portion 5 on which the convex portion 7 is formed. It is to form wrinkles with high flatness while suppressing wrinkles.

  Although the press-formed product 1 shown in FIG. 2 has a U-shaped cross-sectional shape, the press-formed product to be formed by the press-forming die and the press-forming method according to the present invention has a vertical shape in which shrinkage flange deformation occurs. The vertical wall portion may have an L-shaped cross-sectional shape as long as it has a wall portion and a flange portion is not provided at the lower end of the vertical wall portion. In other words, the vertical wall portion has a contracted flange deformation. Any press-formed product may be used.

  Further, the press-formed product 1 has a shape curved upwardly convexly in a side view. For example, a top plate portion curved convexly laterally in a plan view, or a top plate portion in both a plan view and a side view. In a press-formed product having a top plate portion curved in a convex shape, the vertical wall portion continuously formed from these top plate portions shrinks and deforms in a flange shape. Applicable to the molding method.

Further, the press-formed product 1 shown in FIG. 2 is one in which five convex portions 7 are formed on the vertical wall portion 5, and the press-formed product to be formed in the present invention is different from other components. Any portion that can secure the joint surface may be used. In addition, for a portion where a large bending deformation (small radius of curvature) does not occur in the vertical wall portion, the number of the convex portions is appropriately set without forming the convex portion. In addition, since the molding load in the press molding can be suppressed, the number of the convex portions is not limited to the above.
Hereinafter, Embodiments 1 to 4 according to the present invention will be described.

[Embodiment 1]
As shown in FIG. 2, the press molding die 41 according to the first embodiment of the present invention has the top plate portion 3 curved, and is formed continuously from the top plate portion 3 via the ridge line portion 4 and contracted. It has a vertical wall portion 5 which is deformed by a flange, and has a flat bearing surface 9 and a convex portion 7 extending in the height direction of the vertical wall portion 5 to form a press-formed product 1 formed on the vertical wall portion 5. As shown in FIG. 1, the punch 43 includes a punch 43, a die 45, and a pad 47. The punch 43 has a punch-side vertical wall forming surface portion 49, and the die 45 is corrugated with the die-side vertical wall forming surface portion 51. And a deformation suppressing surface portion 53.
Hereinafter, each of the above configurations will be described in detail.

<Punch>
As shown in FIG. 1, the punch 43 has a punch-side vertical wall forming surface portion 49 for forming the vertical wall portion 5. The punch-side vertical wall forming surface portion 49 has a flat seating surface and a vertical wall portion 5. Is formed in a convex shape forming portion 55 extending in the height direction of the first embodiment.
The convex shape forming portion 55 is for forming the convex shape portion 7 on the vertical wall portion 5 in the process of forming the press-formed product 1, and a plurality of the convex shape forming portions 55 are formed in the longitudinal direction in FIG.

<Die>
As shown in FIG. 1, the die 45 is provided continuously below the die-side vertical wall forming surface portion 51 and the die-side vertical wall forming surface portion 51, and is provided before the die-side vertical wall forming surface portion 51 in the forming process. And a wavy deformation suppressing surface portion 53 that comes into contact with the blank 31.
The die-side vertical wall forming surface portion 51 forms the vertical wall portion 5 in cooperation with the punch-side vertical wall forming surface portion 49, and corresponds to the convex shape forming portion 55 formed on the punch-side vertical wall forming surface portion 49. A concave portion 57 is formed at a portion where the protrusion 43 is formed, and a convex portion 59 protruding toward the punch 43 is formed between the concave portions 57. Therefore, the surface of the die-side vertical wall forming surface portion 51 has an uneven shape.

The wavy deformation suppressing surface portion 53 is formed flat in the bending blade R portion 23 of the die 15 (FIG. 3A) without a step over the entire length in the longitudinal direction. The entirety of the wall forming surface portion 51 becomes a blank contact surface portion 53a that contacts the blank before the wall forming surface portion 51.
And in the process of bending and forming the blank 31 in a state where the blank contact surface portion 53a is in contact with the blank 31, generation of wavy deformation of the blank 31 is suppressed.

  Here, the blank contact surface portion 53a shown in FIG. 1 is provided so as to be flush with the bottom surface of the concave portion 57, but the blank contact surface portion 53a according to the first embodiment is provided in the longitudinal direction of the die. The surface is not limited to the one whose surface is flush with the bottom surface of the concave portion 57 as long as it is formed so as to have no unevenness over the entire length.

  The press-molding die 41 according to the first embodiment includes the pad 47, but the pad 47 for pressing the blank 31 is not always required.

Next, a press forming method according to the first embodiment will be described.
The press forming method according to the first embodiment is for forming the press-formed product 1 using the press-forming die 41 shown in FIG. A vertical wall forming step of forming the vertical wall portion 5 by relatively moving the die 45 and the die 45. In the vertical wall forming step, the blank contact surface portion 53a, which is the wavy deformation suppressing surface portion 53 of the die 45, is applied to the blank 31. A first bending step in which the die 45 is relatively moved toward the punch 43 in the contact state, and a second step in which the die 45 is relatively moved to the bottom dead center in the state in which the wavy deformation suppressing surface 53 is separated from the blank 31. And a bending step.

  Hereinafter, the first bending step and the second bending step of the press forming method according to the first embodiment will be described with reference to FIG. FIG. 5 is an analysis result of the deformation behavior of the blank 31 obtained by the press molding analysis in the process of forming the press molded product 1 by the press molding die 41. The punch 43, the pad 47, and the blank 31 are illustrated without displaying 45 (see FIG. 1).

<First bending process>
The first bending step is a step of relatively moving the die 45 toward the punch 43 in a state where the blank contact surface 53a, which is the wavy deformation suppressing surface 53 of the die 45, is in contact with the blank 31.

In the first bending step, the blank 31 is deformed as shown in FIGS.
First, when the die 45 is relatively moved toward the punch 43 in a state where the upper surface of the blank 31 is pressed by the pad 47, the blank contact surface 53a of the die 45 contacts the surface of the blank 31, and the bending deformation of the blank 31 is reduced. Start (FIG. 5B).

  As described above, since the blank contact surface portion 53a is flattened without the step between the concave portion 57 and the convex portion 59, the blank 31 comes into contact with the entire surface of the blank contact surface portion 53a, and the conventional press molding is performed. Bending is performed while maintaining a relatively flat shape without causing a wavy deformation (FIGS. 4B to 4D) as in the case of forming using the mold 11 (FIGS. 5B to 5D). d) A part surrounded by a middle broken line ellipse).

<Second bending process>
The second bending step is a step of relatively moving the die 45 to the bottom dead center of the forming process in a state where the wavy deformation suppressing surface 53 is separated from the blank 31.

In the second bending process, the blank 31 is deformed as shown in FIGS.
In the first bending step, after the die 45 is relatively moved toward the punch 43 in a state where the blank contact surface portion 53a is in contact, the wavy deformation suppressing surface portion 53 of the die 45 is separated from the surface of the blank 31, and FIG. As shown in (), the convex portion 59 (FIG. 1) of the die-side vertical wall forming surface portion 51 comes into contact with the blank 31, and a gently uneven shape is generated.

  When the die 45 is relatively moved to the bottom dead center of the molding, the blank 31 is pressed between the punch-side vertical wall forming surface portion 49 and the die-side vertical wall forming surface portion 51, and as shown in FIG. The press-formed product 1 in which the convex portion 7 is formed on the vertical wall portion 5 is formed.

  As described above, by using the press-molding die 41 according to the first embodiment, it is possible to suppress the occurrence of wavy deformation of the blank 31 due to the contact of the blank contact surface 53a with the blank 31 from the initial stage of molding. Since the blank 31 can be bent and formed while keeping it relatively flat, generation of wrinkles on the seating surface 9 of the convex portion 7 of the press-formed product 1 is suppressed, and the flatness of the seating surface 9 is formed high. be able to.

[Embodiment 2]
The press-molding die 61 according to the second embodiment of the present invention is for molding the press-formed product 1 shown in FIG. 2, and has a punch 43, a die 63, and a pad 47 as shown in FIG. The punch 43 has a punch-side vertical wall forming surface portion 49, and the die 63 has a die-side vertical wall forming surface portion 65 and a wavy deformation suppressing surface portion 67.

  The punch 43 and the pad 47 of the press mold 61 have the same functions as those of the press mold 41 according to the first embodiment. 2 will be described.

<Die>
As shown in FIG. 6, the die 63 is provided continuously below the die-side vertical wall forming surface portion 65 and the die-side vertical wall forming surface portion 65, and is provided before the die-side vertical wall forming surface portion 65 in the forming process. And a wavy deformation suppressing surface portion 67 that comes into contact with the blank 31.

  The die-side vertical wall forming surface portion 65 is for forming the vertical wall portion 5 in cooperation with the punch-side vertical wall forming surface portion 49, and corresponds to the convex shape forming portion 55 formed on the punch-side vertical wall forming surface portion 49. A concave portion 69 is formed at the portion where the protrusion 43 is formed, and a convex portion 71 protruding toward the punch 43 is formed between the concave portions 69. Therefore, the surface of the die-side vertical wall forming surface portion 65 has an uneven shape.

  As shown in FIG. 6, the wavy deformation suppressing surface portion 67 has a flat-shaped blank contact surface portion 67 a at the center in the longitudinal direction, and a die-side vertical wall forming surface portion 65 on both sides in the longitudinal direction of the blank contact surface portion 67 a. It has a concave-convex portion 67b in which a concave portion 69 and a convex portion 71 are formed.

  The blank contact surface portion 67a is wider than the concave portion 69 at the center of the die-side vertical wall forming surface portion 65, and contacts the surface of the blank 31 before the die-side vertical wall forming surface portion 65 at the center in the forming process. Thus, the wavy deformation of the blank 31 is suppressed.

  Here, the blank contact surface portion 67a shown in FIG. 6 is provided such that the surface thereof is flush with the bottom surface of the concave portion 69. However, the blank contact surface portion according to the second embodiment has a concave portion. The surface is not limited to the one whose surface is flush with the bottom surface of the concave portion 69 as long as it is wider than 69 and formed so as to have no irregularities.

Next, a press molding method according to the second embodiment will be described.
The press-forming method according to the second embodiment is for forming the press-formed product 1 using the press-forming die 61 shown in FIG. A vertical wall forming step of forming the vertical wall portion 5 by relatively moving the die 63 and the vertical wall portion 5. The vertical wall forming step includes a blank contact surface portion which is a part of the wavy deformation suppressing surface portion 67 of the die 63. A first bending step in which the die 63 is relatively moved toward the punch 43 with the abutment of the die 67a, and then, the die 63 is relatively moved to the bottom dead center in the state in which the wavy deformation suppressing surface portion 67 is separated from the blank 31; And a second bending forming step.

  Hereinafter, the first bending step and the second bending step of the press forming method according to the second embodiment will be described with reference to FIG. FIG. 7 is an analysis result of the deformation behavior of the blank 31 obtained by the press forming analysis in the process of forming the press-formed product 1 by the press-forming die 61. The punch 43, the pad 47, and the blank 31 are illustrated without displaying 63 (see FIG. 6).

<First bending process>
The first bending step is a step of relatively moving the die 63 toward the punch 43 with the blank 31 in contact with the blank contact surface 67 a which is a part of the wavy deformation suppressing surface 67 of the die 63.

In the first bending process, the blank 31 is deformed as shown in FIGS.
First, when the die 63 is relatively moved toward the punch 43 in a state where the upper surface of the blank 31 is pressed by the pad 47, the wavy deformation suppressing surface portion 67 of the die 63 comes into contact with the surface of the blank 31, and the deformation of the blank 31 starts. (FIG. 7B).

  In the first bending step, since the flat blank contact surface 67a abuts on the surface of the blank 31, the central part of the blank 31 is bent while maintaining relatively flatness (FIG. 7 (b)). ) To (d) a portion surrounded by an ellipse with a broken line in the middle).

<Second bending process>
The second bending process is a process of relatively moving the die 63 to the bottom dead center of the forming process in a state where the wavy deformation suppressing surface 67 is separated from the blank 31.

  After the die 63 is relatively moved toward the punch 43 in a state where the blank contact surface 67a is in contact with the blank in the first bending process, the wavy deformation suppressing surface 67 of the die 63 is moved in the second bending process. As shown in FIG. 7 (e), the convex portion 71 of the die-side vertical wall forming surface portion 65 comes into contact with the blank 31, causing a gradual deformation of the uneven shape.

  Then, when the die 63 is relatively moved to the bottom dead center of the molding, the blank 31 is pressed between the punch-side vertical wall forming surface portion 49 and the die-side vertical wall forming surface portion 65, and as shown in FIG. The press-formed product 1 in which the convex portion 7 is formed on the vertical wall portion 5 is formed.

  As described above, by using the press-molding die 61 according to the second embodiment, the blank 31 is prevented from being deformed in a wavy manner due to the blank contact surface 67a abutting on the blank 31 during the molding. Since the blank 31 can be bent and formed while keeping the target flat, the occurrence of wrinkles on the seating surface 9 of the convex portion 7 of the press-formed product 1 is suppressed, and the flatness of the seating surface 9 can be formed high. it can.

[Embodiment 3]
The press molding method according to the third embodiment of the present invention is a method of molding the press molded product 1 shown in FIG. 2 using the press molding die 41 (see FIG. 1) according to the first embodiment of the present invention. As shown in FIG. 8, a grooved blank forming step (FIG. 8A) for forming a grooved blank 87 having a downwardly convex groove-shaped portion 89 is formed. A vertical wall forming step (FIG. 8 (b)) of mounting and vertically moving the punch 43 and the die 45 to form the vertical wall portion 5 is provided.

In the press forming method according to the third embodiment, the use of the grooved blank 87 in which the lower convex groove-shaped portion 89 is formed is performed by, from the initial stage of molding, contracting the lower convex groove-shaped portion 89 to concentrate the flange deformation. This is because a portion corresponding to the bearing surface 9 of the convex portion 7 of the press-formed product 1 is formed while being kept flat.
Hereinafter, each step of the press molding method according to the third embodiment will be described.

<Groove blank forming process>
As shown in FIG. 9 (b), the grooved blank forming step includes, as shown in FIG. 9 (b), portions a to d (see FIG. 9 (a)) corresponding to the vertical wall 5 A grooved blank 87 in which a plurality of downwardly protruding groove-shaped portions 89a to 89d are formed at predetermined intervals downward (as opposed to the convex shape of the convex portion 7) as groove-shaped portions extending in the direction corresponding to the direction. This is the step of performing

  For forming the grooved blank 87, for example, as shown in FIG. 8A, an upper die 83 and a lower die 85 each having lower convex groove-shaped forming portions 83a and 85a forming a lower convex groove-shaped portion 89 are formed. A preforming die 81 can be used.

  Note that the X, Y, and Z axes in FIG. 9A are the longitudinal direction, the width direction, and the height direction of the press-formed product 1, respectively. In FIG. 9, a half portion of the press-formed product 1 in the width direction (Y direction) is illustrated.

  Further, the grooved blank 87 shown in FIG. 9B is formed with downwardly convex groove-shaped portions 89a to 89d at portions a to d corresponding to the centers of the convex portions 7a to 7e formed on the vertical wall portion 5. The X coordinates of the downwardly convex groove-shaped portions 89a to 89d are defined based on the X coordinates of the parts a to d.

  Further, the lower convex groove-shaped portions 89a to 89d have a concave shape with a length of 75 mm, a width of 7 mm, and a depth of 3 mm, and the depth of the lower convex groove-shaped portions 89a to 89d at the distal end 10 mm is from the surface of the blank 31. It is set so as to gradually change to the bottom surfaces of the lower convex groove portions 89a to 89d. However, the groove-shaped portion formed in the blank in the present invention is not limited to the above dimensions, and the dimension of the groove-shaped portion can be appropriately set. Further, the number of groove-shaped portions formed in the blank may be appropriately set in accordance with the number of convex-shaped portions of the press-formed product to be formed.

<Vertical wall forming process>
In the vertical wall forming step, as shown in FIG. 8B, the punch 43 and the die 45 are formed while the grooved blank 87 is placed on the punch 43 and the upper surface of the grooved blank 87 is pressed by the pad 47. This is a step of forming the vertical wall portion 5 in which the protruding portions 7 are formed between the plurality of lower protruding groove portions 89 formed in the grooved blank forming step by relatively moving to the bottom dead center. It has a forming step and a second bending step.
In the press-formed product 1 shown in FIG. 9A, the convex portions 7b to 7d are formed between the lower convex groove-shaped portions 89a to 89d (FIG. 9B), and further, the convex portions 7b to 7d are formed. Are formed with convex portions 7a and 7e on both sides in the longitudinal direction.

  The first bending step and the second bending step in the vertical wall forming step will be described below with reference to FIG. FIG. 10 is an analysis result of the deformation behavior of the grooved blank 87 obtained by the press forming analysis in the process of forming the press-formed product 1 by the press forming die 41. For this reason, the punch 43, the pad 47, and the grooved blank 87 are shown without displaying the die 45 (see FIG. 6).

<< First bending process >>
The first bending step is a step of relatively moving the die 45 toward the punch 43 with the blank contact surface 53a (see FIG. 8), which is the wavy deformation suppressing surface 53 of the die 45, in contact with the grooved blank 87. It is.
In the first bending process, the grooved blank 87 is deformed as shown in FIGS.

  First, when the die 45 is relatively moved toward the punch 43 in a state where the upper surface of the grooved blank 87 is pressed by the pad 47 (FIG. 10A), the blank contact surface 53a of the die 45 The surface of the grooved blank 87 starts to be deformed by contact with the surface (FIG. 10B).

  As described above, the blank contact surface portion 53a has a flat shape, and when the die 45 is relatively moved to the punch 43 side, the flange deformation is concentrated on the downwardly convex groove-shaped portion 89. As a result, in the first bending step, the lower convex groove-shaped portions 89 are bent and formed while being kept relatively flat (portions surrounded by broken-line ellipses in FIGS. 10B to 10D). .

≪Second bending process≫
The second bending process is a process in which the die 45 is relatively moved to the bottom dead center of the forming process in a state where the wavy deformation suppressing surface portion 53 is separated from the grooved blank 87.
In the second bending step, the grooved blank 87 is deformed as shown in FIGS.

  In the second bending process, the wavy deformation suppressing surface portion 53 of the die 45 is separated from the surface of the grooved blank 87, and the convex portion 59 of the die-side vertical wall forming surface portion 51 comes into contact with the lower convex groove-shaped portion 89 of the blank 31. (FIG. 10 (e)).

  Then, in the process of relatively moving the die 45 to the forming bottom dead center (FIGS. 10E to 10F), the lower convex groove-shaped portion 89 is formed by the punch-side vertical wall forming surface portion 49 and the die-side vertical wall forming surface portion 51. At the bottom dead center of the molding (FIG. 10 (f)), the press-formed product 1 in which the convex portion 7 is formed on the vertical wall portion 5 is formed.

  As described above, according to the press forming method according to the third embodiment, since the shrinkage and flange deformation concentrate on the lower convex groove-shaped portions 89 during the molding, the space between the lower convex groove-shaped portions 89 is kept relatively flat. The convex portion 7 can be formed while being leaned, and the occurrence of wrinkles on the seat surface 9 of the convex portion 7 can be suppressed, and the flatness of the seat surface 9 can be increased.

  In the above description, the lower convex groove-shaped portions 89a to 89d shown in FIG. 9 are formed in a convex shape in a direction opposite to the convex shape of the convex shape portion 7 formed in the press-formed product 1. The groove-shaped portion formed in the blank in the grooved blank forming step does not limit the direction of the unevenness.

  That is, for example, as shown in FIG. 11, the press forming method according to the third embodiment uses a grooved blank 97 in which an upwardly convex groove-shaped portion 99 having an upwardly convex shape is formed. May be formed.

  In this case, in the grooved blank forming step, as shown in FIG. 11A, the upper mold 93 and the lower mold 95 each having upper convex groove forming sections 93a and 95a forming the upper convex groove forming section 99 are formed. The preforming mold 91 is used to form a groove-shaped portion extending from the lower end of the vertical wall portion 5 in a direction corresponding to the height direction at a portion corresponding to the vertical wall portion 5 of the blank 31 so as to project from the press-formed product 1. A grooved blank 97 in which a plurality of upwardly convex groove-shaped portions 99 that are convex in the same direction as the convex shape of the shape portion 7 are formed at predetermined intervals is formed.

  Then, in a subsequent vertical wall forming step, as shown in FIG. 11B, a plurality of upper convex groove-shaped portions are formed by using a press forming die 41 having a punch 43, a die 45, and a pad 47. The vertical wall portion 5 in which the convex portion 7 is formed between 99 is formed.

  The deformation behavior of the grooved blank 97 obtained by press forming analysis in the process of forming the press-formed product 1 using the grooved blank 97 will be described below based on the analysis result shown in FIG. In FIG. 12, the punch 43, the pad 47, and the grooved blank 97 are shown without displaying the die 45 (see FIG. 11) so that the deformation of the grooved blank 97 is easily seen.

  In the case of using the grooved blank 97 having the upper convex groove-shaped portion 99 formed therein, in the first bending forming step in which the blank contact surface portion 53a of the die 45 is formed in contact with the grooved blank 97, the upper convex groove shape is formed. In the case where the grooved blank 87 having the above-mentioned lower convex groove-shaped portion 89 is used, although the portion 99 comes into contact with the blank contact surface portion 53a and is deformed into a somewhat concave shape between the upper convex groove-shaped portions 99 (FIG. Similarly to 10), since the shrinkage flange deformation concentrates on the upper convex groove-shaped portion 99, the space between the upper convex groove-shaped portions 99 is kept relatively flat (the elliptical broken line in FIGS. 12B to 12D). Part surrounded by).

  Then, in the second bending forming step of further moving the die 45 with the blank contact surface portion 53a separated from the grooved blank 97, the upper convex groove shape portion 99 is formed into a concave shape, and the upper convex groove shape portion is formed. The convex portions 7 are formed in a state where the plastic deformation during 99 is reduced (FIGS. 12E to 12F).

  As described above, even when the grooved blank 97 having the upper convex groove-shaped portion 99 is used, by contracting the flange deformation in the upper convex groove-shaped portion 99 in the molding process, the gap between the upper convex groove-shaped portion 99 is formed. Can be bent and formed flat, and the generation of wrinkles on the seating surface 9 of the convex portion 7 can be suppressed, and the seating surface 9 can be formed with high flatness.

  It is to be noted that the lower protruding groove-shaped portion 89 or the upper protruding groove-shaped portion 99 formed in the blank 31 still has a bending habit even at the bottom dead center of the molding, and may be wrinkled in the press-formed product 1. Since the portion corresponding to the lower protruding groove-shaped portion 89 or the upper protruding groove-shaped portion 99 in the press-formed product 1 is between the protruding portions 7, even if wrinkles are generated, it is not a joint surface with other components. It does not matter.

[Embodiment 4]
The press forming method according to the fourth embodiment of the present invention is a method of forming the press-formed product 1 shown in FIG. 2 by using the press-forming die 61 (see FIG. 6) according to the second embodiment of the present invention. As shown in FIG. 13, a grooved blank forming step (FIG. 13A) for forming a grooved blank 87 having a downwardly convex grooved portion 89 is formed. A vertical wall forming step (FIG. 13B) of mounting and vertically moving the punch 43 and the die 45 to form the vertical wall portion 5 is provided.

  Here, in the press forming method according to the fourth embodiment, the reason why the grooved blank 87 is used is that, similarly to the press forming method according to the third embodiment described above, the contraction flange in the downwardly convex groove-shaped portion is formed from the initial stage of molding. This is for the purpose of concentrating the deformation and bending the press-formed product 1 while keeping the portion corresponding to the seating surface 9 of the convex portion 7 more flat.

  The grooved blank forming step in the fourth embodiment is the same as the grooved blank forming step in the press forming method according to the third embodiment described above, and therefore, the vertical wall forming step will be described below.

<Vertical wall forming process>
In the vertical wall forming step, the grooved blank 87 is placed on the punch 43, and the punch 43 and the die 63 are relatively moved to the forming bottom dead center while the upper surface of the grooved blank 87 is pressed by the pad 47. And forming the vertical wall portion 5 having the convex portion 7 formed between the plurality of lower convex groove portions 89 formed in the blank forming step. The first bending step and the second bending step are performed. Have.

  The first bending process and the second bending process in the vertical wall forming process will be described below with reference to FIG. FIG. 14 is an analysis result of the deformation behavior of the grooved blank 87 obtained by the press forming analysis in the process of forming the press-formed product 1 by the press forming die 61. For this reason, the punch 43, the pad 47, and the grooved blank 87 are shown without displaying the die 63 (see FIG. 13).

<< First bending process >>
The first bending process is a process of relatively moving the die 63 toward the punch 43 with the blank contact surface 67a of the die 63 in contact with the grooved blank 87.

In the first bending step, the grooved blank 87 is deformed as shown in FIGS.
First, when the die 63 is relatively moved toward the punch 43 in a state where the upper surface of the grooved blank 87 is pressed by the pad 47, the wavy deformation suppressing surface portion 67 of the die 63 comes into contact with the surface of the grooved blank 87, and the grooved groove 87 is formed. The deformation of the blank 87 starts (FIG. 14B).

  As described above, the blank contact surface portion 67a has a flat shape, and when the die 63 is relatively moved to the punch 43 side, the shrinkage and the flange deformation concentrate on the downwardly convex groove-shaped portion 89. Thereby, in the first bending step, the lower convex groove-shaped portions 89 are bent and formed while being kept relatively flat (portions surrounded by broken-line ellipses in FIGS. 14B to 14D). .

≪Second bending process≫
The second bending forming step is a step of relatively moving the die 63 to the bottom dead center of the forming in a state where the wavy deformation suppressing surface portion 67 is separated from the grooved blank 87.

  In the second bending process, the wavy deformation suppressing surface 67 of the die 63 is separated from the surface of the grooved blank 87, and the convex portion 71 (see FIG. 6) of the die-side vertical wall forming surface 65 contacts the grooved blank 87. (FIG. 14 (e)).

  Then, in the process of relatively moving the die 63 to the molding bottom dead center, the lower convex groove-shaped portion 89 is crushed by the punch-side vertical wall molding surface portion 49 and the die-side vertical wall molding surface portion 51, and the molding bottom dead center (FIG. At 14 (f)), the press-formed product 1 in which the convex portions 7 are formed on the vertical wall portions 5 is formed.

  As described above, according to the press forming method according to the fourth embodiment, since the shrinkage and flange deformation concentrate on the lower convex groove-shaped portion 89 during the molding, the space between the lower convex groove-shaped portions 89 is kept relatively flat. The protruding portion 7 can be formed as it is, and the occurrence of wrinkles on the seating surface 9 of the protruding portion 7 can be suppressed, and the flatness of the seating surface 9 can be formed high.

  Further, according to the press-forming method according to the fourth embodiment, as shown in the examples described later, the generation of wrinkles at the longitudinal end of the ridge 4 (see FIG. 2) of the press-formed product 1 is suppressed. It is more preferable.

  In the above description, the lower convex groove-shaped portions 89a to 89d shown in FIG. 9 are formed in a convex shape in a direction opposite to the convex shape of the convex shape portion 7 formed in the press-formed product 1. The groove-shaped portion formed in the blank in the grooved blank forming step does not limit the direction of the unevenness.

  That is, for example, as shown in FIG. 15, the press forming method according to the fourth embodiment of the present invention employs a press forming method using a grooved blank 97 in which an upwardly convex groove-shaped portion 99 having an upwardly convex shape is formed. The product 1 may be molded.

  In this case, in the grooved blank forming step, as shown in FIG. 15A, the upper mold 93 and the lower mold 95 each having upper convex groove shape forming portions 93a and 95a forming the upper convex groove shape portion 99 are formed. The preforming mold 91 is used to form a groove-shaped portion extending from the lower end of the vertical wall portion 5 in a direction corresponding to the height direction at a portion corresponding to the vertical wall portion 5 of the blank 31 so as to project from the press-formed product 1. A grooved blank 97 in which a plurality of upwardly convex groove-shaped portions 99 that are convex in the same direction as the convex shape of the shape portion 7 are formed at predetermined intervals is formed.

  Then, in a subsequent vertical wall forming step, as shown in FIG. 15B, a plurality of upper convex groove-shaped portions 99 are formed by using a press forming die 61 having a punch 43, a die 63, and a pad 47. The vertical wall portion 5 having the convex portion 7 formed therebetween is formed.

  The deformation behavior of the grooved blank 97 obtained by press forming analysis in the process of forming the press-formed product 1 using the grooved blank 97 will be described below based on the analysis result shown in FIG. In FIG. 16, the punch 43, the pad 47, and the grooved blank 97 are shown without displaying the die 63 (see FIG. 15) so that the deformation of the grooved blank 97 is easily seen.

  In the case where the grooved blank 97 having the upper convex groove-shaped portion 99 is used, in the first bending forming step of forming the die 63 by bringing the blank contact surface 67a into contact with the grooved blank 97, the upper convex groove is formed. In the case where the grooved blank 87 in which the above-mentioned lower convex groove-shaped part 89 is formed is used, although the part 99 is in contact with the blank contact surface part 67a and is slightly deformed between the upper convex groove-shaped parts 99 (FIG. Similar to 14), since the shrinkage flange deformation concentrates on the upper convex groove-shaped portions 99, the space between the upper convex groove-shaped portions 99 is kept relatively flat (the dashed ellipses in FIGS. 16B to 16D). Part surrounded by).

  Then, in the second bending forming step of further moving the die 63 in a state where the blank contact surface 67a is separated from the grooved blank 97, the upper convex groove-shaped portion 99 is deformed into a concave shape, and the upper convex groove-shaped portion is deformed. The convex portions 7 are formed in a state where the plastic deformation during 99 is reduced (FIGS. 16E to 16F).

  As described above, even when the grooved blank 97 having the upper convex groove-shaped portion 99 is used, by contracting the flange deformation in the upper convex groove-shaped portion 99 in the molding process, the gap between the upper convex groove-shaped portion 99 is formed. Can be bent and formed flat, and the generation of wrinkles on the seating surface 9 of the convex portion 7 can be suppressed, and the seating surface 9 can be formed with high flatness.

  It is to be noted that the lower protruding groove-shaped portion 89 or the upper protruding groove-shaped portion 99 formed in the blank 31 still has a bending habit even at the bottom dead center of the molding, and may be wrinkled in the press-formed product 1. Since the portion corresponding to the lower protruding groove-shaped portion 89 or the upper protruding groove-shaped portion 99 in the press-formed product 1 is between the protruding portions 7, even if wrinkles are generated, it is not a joint surface with other components. It does not matter.

Verification for confirming the effects of the press-molding die and the press-forming method according to the present invention has been performed, and this will be described below.
In the present embodiment, the press-formed product 1 shown in FIG. 9A is subjected to press-forming analysis and spring-back analysis, and based on the analysis result of the press-formed product 1 after spring-back, the press-formed product 1 The occurrence of wrinkles on the bearing surface 9 of the convex portion 7 was evaluated.

The press-formed product 1 to be analyzed has a total length in the longitudinal direction of 300 mm, a width of the top plate 3 and a radius of curvature of curvature of 70 mm and 1000 mm, and a width of the bearing surface 9 of the convex portion 7 of 25 mm. Analysis when the height (height of the vertical wall portion 5) is changed in the range of 40mm to 65mm, and the seat height of the convex portion 7 (the height from the bottom surface of the convex shape to the seat surface) is changed in the range of 5 to 7mm. Was done. In the analysis, the blank 31 was a steel plate having a tensile strength of 1180 MPa and a plate thickness of 1.6 mm.
The finite element method analysis software LS-DYNA (manufactured by LSTC) was used for the press-forming analysis and the springback analysis of the press-formed product 1.

  In the present embodiment, the seating surface 9 of the convex portion 7 of the press-formed product 1 is obtained by three items shown in FIG. 17 (a) the thickness increase rate, (b) the equivalent plastic strain, and (c) the maximum radius of curvature. The generation of wrinkles at the ridge 4 (see FIG. 2) was evaluated.

  The sheet thickness increase rate represents an increase in the sheet thickness of the press-formed product 1 based on the sheet thickness of the blank 31. At a portion where the value of the sheet thickness increase rate is large, the in-plane compressive load is large. It is thought that it is suggested that it is easy to buckle and wrinkles easily occur.

  The equivalent plastic strain is a value obtained by converting the strain due to plastic deformation into a uniaxial equivalent.Where the equivalent plastic strain is large, the amount of plastic deformation is large and the bending habit is likely to remain, so wrinkles are likely to occur. Can be

  The minimum bending radius is the minimum value of the radius of curvature in the forming process when the shape of the portion corresponding to the lower end of the convex portion 7 in the blank 31 is represented by the radius of curvature. It is considered that wrinkles are likely to occur on the bearing surface 9 of the convex portion 7.

  The validity of the evaluation of wrinkle generation by the above three items was changed by changing the vertical wall forming height and the seating surface height of the convex portion 7 in the press-formed product 1 formed using the conventional press-forming die 11. Now that we have verified the case, we will explain this first.

  FIG. 18 shows a case where a press-formed product 1 having a vertical wall forming height of 40 mm and a seating surface height of the convex portion 7 of 7 mm is formed by using the press forming die 11 without providing the groove portion in the blank 31. 5 shows an analysis result of a radius of curvature of a portion corresponding to the lower end of the convex portion 7 in the forming process of FIG.

  In FIG. 18, the horizontal axis represents the die stroke (mm) during the relative movement of the die 15 to the bottom dead center of the molding, and the vertical axis represents the convex shape formed at the longitudinal center of the vertical wall portion 5 of the press-formed product 1. It is a radius of curvature (mm) calculated from the end shape of the blank 31 at a portion corresponding to the lower end of the portion 7. Here, the radius of curvature is defined as the radius of a circle passing through three points: a point corresponding to the longitudinal middle point at the lower end of the bearing surface 9c (FIG. 9) of the convex portion 7c and a point 1.5 mm apart on both sides thereof ( FIG. 17D).

  As shown in FIG. 18, the radius of curvature in the forming process decreases sharply near the die stroke of 40 mm where the die 15 comes into contact with the blank 31 and starts forming, and shows a minimum value near the die stroke of 80 mm. It shows a tendency to increase again as the bearing surface of the convex portion 7c is formed flat toward the bottom dead center. Then, from the results shown in FIG. 18, the minimum bending radius is determined to be 9 mm which is the minimum value of the radius of curvature in the forming process.

  In FIG. 19, the vertical wall forming height (height of the vertical wall portion 5) of the press-formed product 1 formed by the press-forming die 11 using the blank 31 is 40 mm (FIG. 19A) and 55 mm (FIG. 19A). 19 (b)) and 65 mm (FIG. 19 (c)) show the results of analysis of each wrinkle occurrence evaluation item (plate thickness increase rate distribution, equivalent plastic strain distribution, and minimum bending radius).

Similarly, in FIG. 20, the height of the seating surface of the convex portion 7 of the press-formed product 1 formed by the press-forming die 11 using the blank 31 is 7 mm (FIG. 20 (a)) and 5 mm (FIG. 20 ( The analysis result of each wrinkle occurrence evaluation item in the case of b)) is shown.
19 and 20, the maximum value of the equivalent plastic strain at the bearing surface 9c of the convex portion 7c and at the end of the ridge portion 4 is also shown.

  The results shown in FIGS. 19 and 20 show that the larger the maximum value of the equivalent plastic strain on the bearing surface 9c of the convex portion 7c, the smaller the minimum bending radius. Then, as the vertical wall forming height of the press-formed product 1 and the bearing surface height of the convex portion 7 increase, wrinkles are more likely to be generated on the bearing surface 9 of the convex portion 7. It was suggested that the minimum bending radius could be used to evaluate wrinkling.

In this example, the occurrence of wrinkles was evaluated for Invention Examples 1 to 7 shown below based on the above verification results.
Inventive Examples 1 and 2 are examples using a die 45 having a wavy deformation suppressing surface 53 over the entire length in the longitudinal direction, as shown in FIG. 1, and molded by a press molding die 41 using a blank 31. In Inventive Example 1, the radius of curvature of the wavy deformation suppressing surface 53 of the die 45 is R20 mm, and in Inventive Example 2, the radius of curvature of the wavy deformation suppressing surface 53 is R100 mm.
Inventive Example 3 is an example in which a die 63 having a wavy deformation suppressing surface portion 67 at the center in the longitudinal direction is used as shown in FIG. is there.

  Inventive Examples 4 and 5 are formed by a press-molding mold 41 using a die 45 having a wavy deformation suppressing surface 53 over the entire length in the longitudinal direction shown in FIG. 1A. As shown in FIG. 8, a grooved blank 87 having a lower convex groove-shaped portion 89 is used. In Invention Example 5, a grooved blank 97 having an upper convex groove-shaped portion 99 is formed as shown in FIG. This is the case when used.

  Inventive Examples 6 and 7 are formed by a press-molding die 61 using a die 63 having a wavy deformation suppressing surface 67 at the center in the longitudinal direction shown in FIG. As shown in FIG. 15, when the grooved blank 87 having the lower convex groove-shaped portion 89 is formed, the invention example 7 has the grooved blank 97 having the upper convex groove-shaped portion 99 formed as shown in FIG. This is a case where is used.

  Inventive Examples 1 to 7 are those in which the vertical wall forming height of the press-formed product 1 is 40 mm and the seating surface height of the convex portion 7 is 7 mm. Then, as a comparative object of the invention examples 1 to 7, it is molded by using the conventional press molding die 11 (see FIG. 3), and the vertical wall molding height of the press molded product 1 and the seat surface height of the convex portion 7 are formed. Those having the same length were set as comparative examples (FIG. 19A).

  FIGS. 21 to 23 show the results of evaluation of wrinkle generation (plate thickness increase rate distribution, equivalent plastic strain distribution, and minimum bending radius) in the press-formed product obtained by the press-forming mold and the press-forming method according to the present invention. Here, FIG. 21 shows the evaluation results of Invention Examples 1 to 3, FIG. 22 shows the evaluation results of Invention Examples 4 and 5, and FIG. 23 shows the evaluation results of Invention Examples 6 and 7.

  In the invention examples 1 to 7 shown in FIGS. 21 to 23, the vertical wall forming height (the height of the vertical wall portion 5) of the press-formed product 1 was 40 mm, and the seating surface height of the convex portion 7 was 7 mm. In this case, the vertical wall forming height (= 40 mm) and the bearing surface height (= 7 mm) were compared with a comparative example (FIG. 19A). 21 to 23 also show the maximum value of the equivalent plastic strain in the bearing surface 9c and the ridge 4 (see FIG. 2) of the convex portion 7c.

In Invention Example 1 (FIG. 21A), the maximum value of the equivalent plastic strain at the bearing surface 9 of the convex portion 7 is 0.08, and the minimum bending radius is 27 mm, which is equivalent to that of the comparative example (FIG. 19A). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
However, the value of the equivalent plastic strain increased at the end of the ridge 4 of the press-formed product 1 and the maximum value (= 0.72) also increased, and wrinkling was observed near the end of the ridge 4.

In Invention Example 2 (FIG. 21B), the maximum value and the minimum bending radius of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 are almost the same as those of Invention Example 1, and the comparative example (FIG. a) As compared with (a)), no wrinkles were observed on the bearing surface 9 of the convex portion 7.
However, compared to the comparative example (FIG. 19A), the value of the equivalent plastic strain near the end of the ridge line portion 4 increased, and wrinkling was observed.

In Invention Example 3 (FIG. 21C), the maximum value of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 is 0.07 and the minimum bending radius is 29 mm, which is equivalent to that of the comparative example (FIG. 19A). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
However, the value of the equivalent plastic strain near the end of the ridge 4 of the press-formed product 1 was high. Although the maximum value (= 0.62) of the equivalent plastic strain in the vicinity of the edge of the ridge 4 was lower than that of the invention examples 1 and 2, wrinkles were observed near the edge of the ridge 4.

In Inventive Example 4 (FIG. 22A), the maximum value of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 is 0.09 and the minimum bending radius is 21 mm, which is equivalent to that of the comparative example (FIG. 19A). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
However, the value of the equivalent plastic strain near the end of the ridge 4 of the press-formed product 1 was high. The maximum value (= 0.45) of the equivalent plastic strain in the vicinity of the edge of the ridge 4 is lower than that of the invention examples 1 to 3, and although the generation of wrinkles is suppressed, the value in the vicinity of the edge of the ridge 4 is small. It did not prevent the occurrence of wrinkles.

In Invention Example 5 (FIG. 22B), the maximum value of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 is 0.13, and the minimum bending radius is 16 mm, which is equivalent to the comparative example (FIG. 19A). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
However, the maximum value of the equivalent plastic strain in the vicinity of the end of the ridge line portion 4 of the press-formed product 1 was 0.49, which was lower than that of Invention Examples 1 to 3 and the generation of wrinkles was suppressed, as in Invention Example 4. However, it was not possible to prevent the generation of wrinkles near the end of the ridge line portion 4.

In Invention Example 6 (FIG. 23A), the maximum value of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 is 0.08, and the minimum bending radius is 26 mm, which is equivalent to that of the comparative example (FIG. 19A). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
Further, the equivalent plastic strain in the vicinity of the edge of the ridge 4 of the press-formed product 1 is substantially the same as that of the comparative example (FIG. 19A), and wrinkling is observed near the edge of the ridge 4. Did not.

In Invention Example 7 (FIG. 23 (b)), the maximum value of the equivalent plastic strain on the bearing surface 9 of the convex portion 7 is 0.13, and the minimum bending radius is 16 mm, which is equivalent to the comparative example (FIG. 19 (a)). The result was better than the maximum value (= 0.17) and the minimum bending radius (= 9 mm) of the plastic strain, and no wrinkles were observed on the bearing surface 9 of the convex portion 7.
Further, as in Invention Example 6, near the end of the ridge line portion 4 of the press-formed product 1, the equivalent plastic strain was almost the same as that of the comparative example (FIG. 19A), and no wrinkling was observed. .

As described above, according to the press-molding die and the press-forming method according to the present invention, the wavy deformation suppressing surface portion for suppressing the wavy deformation of the blank is provided below the die-side vertical wall forming surface portion, and the wavy deformation is performed in the forming process. By causing the blank contact surface portion of the suppression surface portion to abut against the blank before the die-side vertical wall molding surface portion, it is possible to suppress the occurrence of wrinkles on the seat surface of the convex portion of the press-formed product, and It has been demonstrated that a press-formed product having a high flatness can be obtained.
Further, by providing the blank contact surface portion at the center in the longitudinal direction of the wavy deformation suppressing surface portion, generation of wrinkles at the end of the ridge portion of the press-formed product in addition to the bearing surface of the convex portion of the press-formed product. Was also able to be suppressed, indicating that it was more preferable.

DESCRIPTION OF SYMBOLS 1 Press molded product 3 Top plate part 4 Ridge line part 5 Vertical wall part 7 Convex part 9 Seat surface 11 Die for press molding 13 Punch 15 Die 17 Pad 19 Punch side vertical wall forming surface part 21 Die side vertical wall forming surface part 23 Bending Blade R portion 25 Convex shape forming portion 27 Die concave portion 29 Die convex portion 31 Blank 41 Press forming die 43 Punch 45 Die 47 Pad 49 Punch side vertical wall forming surface portion 51 Die side vertical wall forming surface portion 53 Wavy deformation suppressing surface portion 53a blank contact surface portion 55 convex shape forming portion 57 die concave portion 59 die convex portion 61 press forming die 63 die 65 die-side vertical wall forming surface portion 67 wavy deformation suppressing surface portion 67a blank contact surface portion 67b uneven portion 69 of die Concave part 71 Die convex part 81 Pre-molding die 83 Upper die 83a Lower convex groove shape forming part 85 Lower die 85a Lower convex groove shape forming part 87 Per blank 89 Shitatotsumizo shaped portion 91 preformed mold 93 upper mold 93a Uetotsumizo shaped molded portion 95 lower mold 95a Uetotsumizo shaped molded portion 97 grooved blank 99 Uetotsumizo shaped portion

Claims (2)

The top plate portion is curved, has a vertical wall portion that is continuously formed from the top plate portion and shrinks and is deformed, and a convex shape portion having a flat seating surface and extending in the height direction of the vertical wall portion is provided. A press molding method for molding a press molded article formed on a vertical wall portion ,
A grooved blank forming step of forming a grooved blank in which a plurality of groove-shaped portions extending in a direction corresponding to the height direction of the vertical wall portion are formed at predetermined intervals in a portion corresponding to the vertical wall portion in the blank; ,
Has a pre-Symbol plurality groove formed shape portion the vertical wall portion bending to the vertical wall forming step of the convex portion is formed between,
The vertical wall forming step includes :
It has a punch and a die,
The punch has a punch-side vertical wall forming surface that forms the vertical wall,
The punch-side vertical wall forming surface portion is formed with a convex shape forming portion that has a flat bearing surface and extends in the height direction,
The die includes a die-side vertical wall forming surface that forms the vertical wall in cooperation with the punch-side vertical wall forming surface, and a die-side vertical wall forming surface that is provided continuously from the die-side vertical wall forming surface. Having a wavy deformation suppressing surface portion that suppresses the occurrence of wavy deformation in the blank by contacting the whole or a part of the blank before the molding surface portion,
The die-side vertical wall forming surface portion has a concave portion formed at a portion corresponding to the convex shape forming portion formed on the punch-side vertical wall forming surface portion,
The wavy deformation suppressing surface portion, using a die for press molding having a blank contact surface portion wider than the concave portion of the die-side vertical wall molding surface portion , placing the grooved blank on the punch, the punch And forming the vertical wall portion by relatively moving the die,
A first bending step of moving the die relatively to the punch side in a state where at least the blank contact surface portion of the wavy deformation suppressing surface portion is in contact with the grooved blank, and then the wavy deformation suppressing surface portion is A press forming method, comprising a second bending step of relatively moving the die to a forming bottom dead center while being away from the grooved blank.   The press-forming method according to claim 1, wherein the blank contact surface portion of the wavy deformation suppressing surface portion extends over the entire length in the longitudinal direction of the die.