JP2022013343A - Press component manufacturing method and metal plate for press molding - Google Patents

Abstract

To alleviate elongation of an area to be elongation-deformed more efficiently when press molding a metal plate into a target press component shape.SOLUTION: According to a press component manufacturing method, when press molding a metal plate into a target press component shape, a position where there is a preset elongation deformation amount or more or a position where it is wanted to increase compressive stress in an area to be elongation-deformed is so made as to be an adjustment part P. The method has, as a press molding process, a first process 3 in which one or more excessive metal parts 20, which are deformed in a plate thickness direction with respect to at least one plate part of both sides with the adjustment part P interposed therebetween, are formed in a deformation direction of elongation deformation, and a second process 4A in which the excessive metal part 20 formed in the first process 3 is collapsed. The excessive metal part 20 formed in the first process 3 has a cross section along the deformation direction of elongation deformation, which becomes an unsymmetrical shape in a direction in which a material movement amount to the adjustment part P relatively becomes more than a material movement amount to a side opposite to the adjustment part P, for example, when being collapsed in the second process 4A.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a pressed part and a metal plate for press forming used thereof.

In recent years, against the background of energy problems and global environmental problems, stamped parts for vehicles are required to be lightweight for the purpose of improving fuel efficiency, and are also required to improve collision characteristics in the event of a collision. In order to meet these two conflicting demands, the application of high-strength steel sheets is expanding as metal plates for press forming used in stamped parts for vehicles and the like. By applying high-strength steel sheets, it is possible to promote weight reduction of the vehicle body and improvement of collision characteristics at the same time.
In promoting weight reduction, it is possible to reduce the weight of the vehicle body while maintaining the collision characteristics by increasing the strength of the metal plate and reducing the plate thickness. When applying a high-strength steel plate, one of the major problems is cracking due to a decrease in ductility due to the increase in strength of the material and deterioration of dimensional accuracy due to springback. As a measure against cracking, many methods using preforming to secure the line length have been proposed.

For example, Patent Document 1 proposes a technique of determining a preformed shape from the amount of deformation at the stretched flange portion and suppressing cracking of the stretched flange portion by crushing the preformed shape (surplus wall portion).
As for springback countermeasures, many methods for alleviating the non-uniformity of residual stress have been proposed. For example, in Pat. We are proposing a technique to level the residual stress distribution by applying tensile stress with the surplus bead.

Japanese Unexamined Patent Publication No. 2019-25509 Japanese Patent No. 5380890

In Patent Document 1, the line length of the preformed shape is determined from the line length required for avoiding cracking. However, since the cross section of each preformed shape is symmetrical, when the preformed shape is crushed, The preformed line length is not efficiently supplied to the cracked portion side and is dispersed to other portions. Therefore, it may be insufficient as a countermeasure against cracking. In addition, when preforming is performed with a line length larger than the line length calculated by the present technology, if the line length becomes excessive, wrinkles may occur.
Further, Patent Document 2 proposes a technique for leveling stress by crushing embossing. However, since the cross section of the emboss is symmetrical, when the emboss is crushed, the material flow direction is dispersed, and it may be difficult to efficiently generate compressive stress at the target location.

The present invention has been made by paying attention to the above points, and an object of the present invention is to more efficiently alleviate the elongation of a region to be stretched and deformed when press-molding into a desired pressed part shape.

As a result of examining the amount of material movement when the surplus portion is crushed, the present inventor has obtained the finding that the material flow direction can be controlled by making the cross-sectional shape of the surplus portion asymmetrical. The present invention has been made based on the findings.

In order to solve the problem, one aspect of the present invention is a method for manufacturing a pressed part in which a metal plate is press-molded to manufacture a pressed part, and is stretched when the metal plate is press-molded into a desired pressed part shape. A direction along the deformation direction of the elongation deformation as a press forming process for manufacturing the press parts, with the position of the deformation region exceeding the preset elongation deformation amount or the position where the compressive stress is desired to be increased as the adjusting portion. In the first step of forming one or two or more surplus portions formed by being deformed in the plate thickness direction with respect to at least one plate portion on both sides of the adjusting portion, and forming in the first step. The gist is to have a second step of crushing the surplus meat portion.

Further, another aspect of the present invention is a metal plate for press-molding into a pressed part, which is a preset elongation-deformation region in a region to be stretch-deformed when the metal plate is press-molded into a desired press-part shape. When the position above the amount or the position where you want to increase the compressive stress is set as the adjustment part, the plate thickness is relative to at least one of both sides of the adjustment part in the direction along the deformation direction of the elongation deformation. The gist is that it has one or more surplus parts that are deformed in the direction.

According to the aspect of the present invention, the material flow direction when the surplus portion is crushed is controlled according to the cross-sectional shape of the surplus portion, so that the amount of material movement to the adjusting portion side where the material is desired to flow is relative. Can be increased. As a result, when press-molding into the desired pressed part shape, for example, the elongation of the stretch-deformed region is more efficiently relaxed to suppress cracking at the stretch flange portion, and the springback factor stress is reduced. It becomes possible to do.

It is a figure which shows the example of the pressed part to which this embodiment is applied. It is a figure explaining the example of the processing process which concerns on embodiment based on this invention. It is a schematic diagram which shows the example of formation of the surplus part, (a) is a figure which shows the case of a bead example, and (b) is a figure which shows the case of embossing example. It is a figure which shows an example of the cross section of a surplus part having a chevron shape. It is a figure which shows an example of the trapezoidal shape in the cross section of the surplus wall part. It is a figure which shows an example of the cross section of a surplus part having an arc shape. It is a figure explaining the tunnel shape model in an Example. It is a figure explaining the bead cross section in 1st Example. It is a figure which shows the evaluation result of 1st Example. It is a figure explaining the simple extension flange deformation model in 2nd Example. It is a figure explaining the bead cross section in 2nd Example. It is a figure which shows the evaluation result of 2nd Example.

Next, an embodiment of the present invention will be described with reference to the drawings.
The technical idea of the present invention does not specify the material, shape, structure, etc. of the constituent parts as follows. Further, the technical idea of the present invention may be modified in various ways within the technical scope specified by the claims described in the claims.

<Pressed parts 1>
In the present embodiment, the case where the target press component shape of the press component 1 has a shape as shown in FIG. 1 will be described as an example. That is, the pressed component 1 of the present embodiment has a shape having a top plate portion 1A, a side wall portion 1B continuous with the top plate portion 1A, and a flange portion 1C continuous with the side wall portion 1B. The shape of the pressed part to which the present invention can be applied is not limited to the L-shaped cross section. The shape of the pressed part may be, for example, a U-shaped cross section, a hat-shaped cross section, an L-shaped cross section, a T-shaped plan view, or the like. The present invention is applicable as long as the metal plate 10 has a press shape in which a plate portion that is stretched and deformed and an adjusting portion P that wants to increase the compressive stress are present when press-molding the metal plate 10 into a desired pressed part shape.

In the present embodiment, the case where the adjusting unit P is at a position equal to or larger than a preset elongation deformation amount in the elongation deformation region when the metal plate 10 is press-formed into a desired press part shape is illustrated. The preset elongation deformation amount is set to, for example, the lower limit elongation deformation amount because it is estimated that there is a risk of cracking due to elongation deformation. The preset elongation deformation amount is, for example, an elongation deformation amount in which the reduction amount of the plate thickness is 5%.
Here, the higher the tensile strength of the blank (metal plate 10 to be press-formed), the more likely it is that cracks will occur due to elongation deformation during press forming. Therefore, in this embodiment, for example, a high-tensile steel plate having a tensile strength of 980 MPa or more is used. Suitable.

However, the blank material to which the present invention can be applied is not limited to steel, but can also be applied to iron alloys such as stainless steel, as well as non-ferrous materials and non-metal materials. Further, the pressed parts 1 manufactured in the present embodiment are suitable as, for example, automobile parts, but the present invention can be applied not only to automobile parts but also to all processes for press-molding plate materials.
Here, it is assumed that when a high-strength steel plate having a tensile strength of 980 MPa is used as a blank and a flat blank is press-formed into the shape of a pressed part shown in FIG. 1, cracks occur in the portion of reference numeral P in FIG. .. Based on this result, in the present embodiment, when the flat metal plate 10 is press-formed into the shape of the pressed part, the flange portion 1C undergoes flange elongation deformation in the direction along the edge, and the stretch flange cracks. The position of the reference numeral P in which the above may occur will be described as the adjusting unit P.

<Manufacturing method of pressed parts 1>
As shown in FIG. 2, the manufacturing method of the pressed part 1 of the present embodiment is formed by the adjustment unit evaluation step 2 for specifying the adjustment unit P, the first step 3 as the preforming process, and the first step 3. The present molding step 4 including the second step 4A for crushing the surplus thickness portion 20 is provided. The main molding step 4 including the first step 3 and the second step 4A constitutes a press molding step.

<Adjustment unit evaluation process 2>
The adjustment unit evaluation step 2 executes a process of specifying the position of the adjustment unit P, which is a position where there is a risk of expansion flange cracking when the flat metal plate 10 is press-molded into a press part shape for the purpose.
In the adjustment unit evaluation step 2, for example, the test product having the desired pressed part shape is actually press-molded, and the position where there is a risk of stretch flange cracking is determined by the plate thickness deformation amount along the flange end edge and the like. Is measured and calculated. Further, in the adjustment unit evaluation step 2, for example, the position where the stretch flange crack occurs in the test product is designated as the adjustment unit P.
Alternatively, in the adjustment unit evaluation step 2, for example, a simulation analysis by CAE by a computer is executed, the distribution of the plate thickness reduction rate and the strain distribution are examined, and the position of the adjustment unit P is specified.
Here, for example, a region where the plate reduction due to press working is 5% or more is designated as the adjusting unit P.

<First step 3>
In the first step 3, with respect to the metal plate 10, at least one of both sides (reference numeral X in FIG. 1) sandwiching the adjusting portion P in the direction along the deformation direction of the elongation deformation. A process of forming one or more surplus thickness portions 20 that are deformed in the plate thickness direction is executed. The formation of the surplus thickness portion 20 may be performed by press working.
The position where the surplus portion 20 is formed is a position where the material can be dispersed from the position of the surplus portion 20 toward the adjusting portion P when the surplus portion 20 is crushed. The formation position of the surplus portion 20 may be determined by a known method.

<Shape of surplus thickness 20>
The surplus meat portion 20 is formed of, for example, beads or embossing. In the case of a bead, the bead extends in a direction intersecting the direction along the deformation direction of the elongation deformation. FIG. 3A is an example of a case where the surplus portion 20 is formed of beads and two beads are provided on one side of the adjusting portion P. FIG. 3B is an example in which the surplus thickness portion 20 is formed by embossing and four embossings are provided on one side of the adjusting portion P.

In the surplus portion 20 formed in the first step 3, when the surplus portion 20 is crushed, the amount of material transferred to the adjusting portion P side becomes larger than the amount of material transferred to the side opposite to the adjusting portion P side. It is preferable that the cross section along the deformation direction of the elongation deformation is asymmetrical in the direction. The direction along the deformation direction of the elongation deformation is the direction along the edge of the flange portion 1C. The direction along the deformation direction of the elongation deformation does not have to completely coincide with the deformation direction of the elongation deformation, and may be a slightly deviated direction.
The cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation is, for example, an adjustment portion with respect to the surplus thickness apex portion Y when the position where the amount of deformation in the plate thickness direction is the largest is the surplus thickness apex portion Y. The width L1 on the P side is narrower than the width L2 on the side opposite to the adjustment portion P side (see FIG. 4).

Alternatively, the cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation is formed on the adjusting portion P side of the left and right sides, for example, and the amount of deformation in the plate thickness direction decreases toward the adjusting portion P side. It is provided with a 1 inclined portion 21 and a second inclined portion 22 formed on the left and right sides opposite to the adjusting portion P and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion P side. The angle β formed by the straight line S1 connecting both ends of the first inclined portion 21 and the straight line 5 in the pressing direction in the second step 4A is the straight line S2 connecting both ends of the second inclined portion 22 and the pressing direction in the second step 4A. The configuration is smaller than the angle α formed by the straight line 5 (see FIG. 4).
The pressing direction in the second step 4A may be the plate thickness direction at the flat portion position of the metal plate 10.
At this time, the cross-sectional portion 20A of the surplus portion 20 may have a portion having another cross-sectional shape between the first inclined portion 21 and the second inclined portion 22 formed on both the left and right sides.
As the basic shape of the cross section 20A of the surplus wall portion 20, a chevron shape, an arc shape, a trapezoidal shape, or the like can be exemplified.

(In the case of chevron shape)
As shown in FIG. 4, a case where the cross section 20A of the surplus wall portion 20 has a chevron shape will be described.
In this case, the cross section 20A of the surplus portion 20 is formed on the adjusting portion P side of the left and right sides, and the first inclined portion 21 in which the amount of deformation in the plate thickness direction decreases toward the adjusting portion P side and the left and right sides. Of these, the second inclined portion 22, which is formed on the side opposite to the adjusting portion P and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion P side, the first inclined portion 21, and the second inclined portion 22. And are connected by the arc portion 23. The angle β formed by the straight line S1 connecting both ends of the first inclined portion 21 and the straight line 5 in the pressing direction in the second step 4A is the straight line S2 connecting both ends of the second inclined portion 22 and the second step 4A. It is configured to be smaller than the angle α formed by the straight line 5 in the pressing direction.
Further, in this cross-sectional shape, when the position where the amount of deformation in the plate thickness direction is the largest is the surplus thickness apex portion Y, the width L1 on the adjustment portion P side with respect to the surplus thickness apex portion Y is the adjustment portion P side. Has a shape narrower than the width L2 on the opposite side.

(Trapezoidal shape)
The shape in which the arc portion 23 is a flat portion 24 in the above-mentioned cross section having a chevron shape is a trapezoidal shape (see FIG. 5).
That is, when the cross section of the surplus portion 20 has a trapezoidal shape, as shown in FIG. 5, it is formed on the adjusting portion P side of the left and right sides, and the amount of deformation in the plate thickness direction decreases toward the adjusting portion P side. The first inclined portion 21 is formed, and the second inclined portion 22 is formed on the left and right sides opposite to the adjusting portion P, and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion P side. The first inclined portion 21 and the second inclined portion 22 are connected by a flat portion 24. The angle β formed by the straight line S1 connecting both ends of the first inclined portion 21 and the straight line 5 in the pressing direction in the second step 4A is the straight line S2 connecting both ends of the second inclined portion 22 and the second step 4A. It is configured to be smaller than the angle α formed by the straight line 5 in the pressing direction. The pressing direction in the second step 4A may be the plate thickness direction at the flat portion position of the metal plate 10.
In the case of this trapezoidal shape, the apex portion Y of the surplus thickness, which is the position where the amount of deformation in the plate thickness direction is the largest, is defined as the center position of the flat portion.
The flat portion 24 may be inclined along the width direction, or may have a curved surface such as an arc shape.

(In the case of arc shape)
When the cross section 20A of the surplus portion 20 has an arc shape, the cross section 20A of the surplus portion 20 is opposite to the first inclined portion 21 on the adjusting portion P side with the surplus wall apex portion Y (bead apex) interposed therebetween. It is divided into a second inclined portion 22. Then, the angle β formed by the straight line S1 connecting both ends of the first inclined portion 21 and the straight line 5 in the pressing direction in the second step 4A connects the both ends of the second inclined portion 22 with the cross section 20A of the surplus portion 20. The arc shape is asymmetrical to the left and right, which is smaller than the angle α formed by the straight line S2 and the straight line 5 in the pressing direction in the second step 4A.
Further, in this cross-sectional shape, when the position where the amount of deformation in the plate thickness direction is the largest is the surplus thickness apex portion Y, the width L1 on the adjustment portion P side with respect to the surplus thickness apex portion Y is the adjustment portion P side. Has a shape narrower than the width L2 on the opposite side.

(About the angle of the first inclined portion 21)
The angle β of the first inclined portion 21 is preferably larger than 10 degrees, more preferably 20 degrees or more.
When the angle β of the first inclined portion 21 is 10 degrees or less, the bead shape may be buckled and folded when the surplus portion 20 is crushed. If they are folded, it may cause wrinkles.

<Main molding process 4>
In the main molding step 4, after the surplus portion 20 is formed on the metal plate 10 in the first step 3, the shape of the molded part is press-molded in one step or multiple steps to form the desired press part shape (final shape). It is a process.
In the main molding step 4, for example, the die is lowered while the top plate portion 1A of the metal plate 10 on which the surplus thickness portion 20 is formed is sandwiched between the punch (lower mold) and the pad from the plate thickness direction. A press process is performed in which the vertical wall portion and the flange portion 1C are formed and the surplus thickness portion 20 is crushed in the plate thickness direction.

In this example, the case where the main molding step 4 and the second step 4A are executed in one step, that is, the case where the main molding step 4 and the second step 4A are executed in one mold is illustrated, but the main molding step 4 and the second step 4A are separated. It may be configured in the process.
In this case, in the second step 4A, press molding is performed to crush the surplus portion 20 formed in the first step 3. Then, in the main forming step 4, the metal plate 10 after the second step 4A is formed into a desired pressed part shape (final shape).

<Operation and others>
When the flat metal plate 10 is formed into the shape of a pressed part as shown in FIG. 1, for example, elongation flange deformation occurs at a portion having a large curvature at a portion where the bending line is curved concavely. For example, the position P is the position of the maximum elongation deformation amount (adjustment unit P).
On the other hand, in the present embodiment, after forming the surplus portion 20 to increase the cross-sectional line length and earning the cross-sectional line length so as to approach the cross-sectional line length of the pressed part shape, the desired pressed part shape is obtained. Press molding is performed to obtain a pressed part 1 having a desired pressed part shape.

As described above, in the present embodiment, the elongation is dispersed by executing the process of forming the surplus portion 20 in advance in the vicinity of the maximum elongation flange position (adjustment portion P) where cracks may occur. It is possible to prevent cracking at the extension flange.
That is, when press-molding with a die in the main forming step 4, the surplus portion 20 starts to be deformed in the direction of being crushed (flattening direction) in contact with the die due to the bending deformation of the flange portion 1C. Then, the formation of the flange portion 1C is completed when the surplus portion 20 is completely crushed. As a result, the increase in the plate thickness reduction rate in the adjusting portion P is suppressed by the flow of the material from the position of the surplus portion 20 to the adjusting portion P side.

At this time, in the present embodiment, the cross section 20A of the surplus portion 20 has a left-right asymmetric shape in the direction along the elongation deformation (in the present embodiment, the direction along the flange end edge), and among the left and right inclined portions, the cross section 20A is formed into a left-right asymmetric shape. The angle β of the straight line S1 defined by the first inclined portion 21, which is the inclined portion on the adjusting portion P side, is set to a relatively small angle.
As a result, it is possible to control the cross-sectional shape of the surplus portion 20 so that the amount of movement of the material flowing to the adjusting portion P side relatively increases when the surplus portion 20 is crushed.
As described above, in the present embodiment, the material flow direction when the surplus portion 20 is crushed is controlled by the cross-sectional shape 20A of the surplus portion 20, and the amount of material movement to the adjusting portion P side is relatively increased. .. As a result, it is possible to more efficiently relax the elongation of the stretch-deformed region when press-molding into the desired pressed part shape.

Further, in the present embodiment, even if the height of the surplus portion 20 is the same (the amount of deformation in the plate thickness direction), the amount of material movement to the adjusting portion P side can be relatively increased, as compared with the conventional case. It is possible to suppress the height of the surplus meat portion 20.
As a result, according to the present embodiment, for example, the occurrence of cracks in the stretch flange portion 1C can be efficiently suppressed.
Here, in the above description, the avoidance of cracking due to the deformation of the stretch flange has been described, but the present embodiment is not limited to this. For example, the surplus portion 20 may be formed for the purpose of reducing the springback factor stress after mold release by press forming into the desired shape of the pressed part. In this case, the amount of springback can be reduced by setting the adjustment unit P at a position where the compressive stress is to be increased and the springback factor stress is to be reduced.

That is, according to the present embodiment, when the cross section 20A of the surplus portion 20 is asymmetrical, the left and right material flow amounts are different, and the angle between the vertical line drawn from the bead apex in the press direction and the bead shape is larger than the other. Based on the knowledge that the amount of material flow on the smaller side increases, a surplus portion 20 having an asymmetric cross section designed according to the direction in which the material is desired to flow is formed, and the surplus portion 20 is formed in the next step. By crushing, it is possible to efficiently take measures against cracking and reduce the stress caused by springback.

<Effect>
This embodiment has the following effects.
(1) The present embodiment is a method for manufacturing a press part 1 in which a metal plate 10 is press-molded to manufacture a press part 1, and when the metal plate 10 is press-molded into a desired press part shape, the metal plate 10 is stretched and deformed. The adjustment unit P is a position that exceeds a preset elongation deformation amount or a position where the compressive stress is desired to be increased, and is a direction along the deformation direction of the elongation deformation as a press forming process for manufacturing the press parts. In the first step 3 and the first step 3 for forming one or more surplus thickness portions 20 which are deformed in the plate thickness direction with respect to at least one plate portion on both sides of the adjusting portion P. It has a second step 4A for crushing the surplus wall portion 20 formed in the step 3.

In the surplus portion 20 formed in the first step 3, for example, when the surplus portion 20 is crushed in the second step 4A, the amount of material transferred to the adjusting portion P side is relatively opposite to that of the adjusting portion P. The cross section along the deformation direction of the elongation deformation is asymmetrical in the direction larger than the amount of material movement.
According to this configuration, the material flow direction when the surplus portion 20 is crushed is controlled by the cross section 20A shape of the surplus portion 20, and the amount of material movement to the adjusting portion P side where the material is desired to flow is relatively increased. It becomes possible to do. As a result, when press-molding into the desired press component shape, for example, the elongation of the stretch-deformed region is more efficiently relaxed to suppress cracking at the stretch flange portion 1C, and the springback factor stress is reduced. It is possible to plan.

(2) The cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation is, for example, when the position where the amount of deformation in the plate thickness direction is the largest is the surplus thickness apex portion Y, the surplus thickness apex. The width of the adjusting portion P with respect to the portion Y is narrower than the width of the side opposite to the adjusting portion P side.
According to this configuration, when crushed in the second step 4A, the amount of material movement to the adjustment unit P side is relatively larger than the amount of material movement to the side opposite to the adjustment unit P. It is possible to make the cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation into a left-right asymmetrical shape.

(3) The cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation is formed, for example, on the adjustment portion P side of the left and right sides, and is deformed in the plate thickness direction toward the adjustment portion P side. A second inclined portion 21 having a smaller amount and a second inclined portion 21 formed on the left and right sides opposite to the adjusting portion P, and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion P side. The angle formed by the straight line S1 connecting both ends of the first inclined portion 21 and the straight line 5 in the pressing direction in the second step 4A is the straight line S2 connecting both ends of the second inclined portion 22. The configuration is smaller than the angle formed by the straight line 5 in the pressing direction in the second step 4A.
According to this configuration, when crushed in the second step 4A, the amount of material movement to the adjustment unit P side is relatively larger than the amount of material movement to the side opposite to the adjustment unit P. It is possible to make the cross section 20A of the surplus portion 20 along the deformation direction of the elongation deformation into a left-right asymmetrical shape.

(4) The surplus thickness portion 20 is formed by beads or embossing.
According to this configuration, the surplus thickness portion 20 can be surely provided.
(5) The present embodiment includes, as the press molding step, the main molding step 4 for molding into the part shape of the target pressed part 1, and the main molding step 4 and the first step 3 are one. Performed in the process.
According to this configuration, the number of steps can be suppressed even if the first step 3 and the second step 4A are carried out.
(6) The adjusting portion P is, for example, a position where there is a possibility of cracking of the stretch flange.
According to this configuration, cracking of the stretched flange can be efficiently suppressed.

(7) The present embodiment is a metal plate 10 for press-molding on a press part 1, and is set in advance in a region to be stretched and deformed when the metal plate 10 is press-molded into a desired press part shape. When the adjustment unit P is a position that exceeds the amount of deformation or a position where the compressive stress is desired to be increased, with respect to at least one plate portion on both sides of the adjustment unit P in the direction along the deformation direction of the elongation deformation. It has one or two or more surplus portions 20 that are deformed in the plate thickness direction.
For example, when the surplus portion is crushed in the plate thickness direction, the amount of material movement to the adjustment unit P side becomes larger than the amount of material movement to the side opposite to the adjustment unit P. The cross section along the deformation direction of the elongation deformation has an asymmetrical shape.
According to this configuration, it is possible to provide a metal plate 10 capable of reducing crack reduction and springback reduction in the stretch flange portion 1C during press molding.

(8) At this time, the metal plate 10 for press molding in the metal plate 10 for press molding according to (7) may be a metal plate 10 for press molding in which the surplus portion 20 is crushed in the plate thickness direction. ..
According to this configuration, it is possible to suppress the process in the press process in which the reduction of cracks and the reduction of springback in the extension flange portion 1C are reduced.

Next, an example for verifying the effect of the present embodiment will be described.
<Example 1>
In Example 1, the amount of material flow when the tunnel-shaped bead shape (the bead shape extending in one direction in a predetermined manner) is crushed by CAE was evaluated.
At this time, the metal plate 10 was a cold-rolled steel plate and was a high-tensile material having a tensile strength of 980 MP class. The plate thickness was set to 0.9 mm.
The mechanical properties of the metal plate 10 are as follows.
-Mechanical characteristic values: YP: 620 MPa, TS: 1030 MPa, El: 15%

As a tunnel-type bead-shaped model, a tunnel-shaped model as shown in FIG. 7 was used. In FIG. 7, reference numeral 10 indicates a metal plate, and reference numerals 50 and 51 indicate molding surfaces of upper and lower dies for crushing the surplus portion.
Further, the cross section of the bead had a chevron shape as shown in FIG. 8, and the left and right bead angles α and β sandwiching the bead apex (remaining apex portion Y) were changed to obtain the material flow amount.
Table 1 shows the dimensions of the beads used for the evaluation.

Further, when the amount of material flow to the left and right of each sample at that time was determined, the results shown in FIG. 9 were obtained.
As can be seen from FIG. 9, it was found that the larger the bead angle β (left side in FIG. 8), the smaller the amount of material flow in that direction.

<Example 2>
In Example 2, in the simple stretch flange deformation model, a bead was arranged on one side of the crack risk portion in the stretch flange portion 1C, and the change in the plate thickness reduction rate was evaluated.
The conditions of the metal plate 10 were set to the same material properties as in Example 1.
FIG. 10 shows a simple extension flange deformation model of the second embodiment.
That is, the part shape of the pressed part 1 was the same as that of FIG. 1, and the condition was that the top plate portion 1A was pressed with a pad for press molding. In FIG. 10, a bead (surplus wall portion 20) is shown in the part shape of the pressed part 1, but under the condition that the metal plate 10 on which the bead is formed is press-molded into the shape shown in FIG. 1 and the shape in which the bead is crushed. , CAE analysis was performed.
The bead shape set in FIG. 11 is shown.
Table 2 shows the bead dimensions of each sample.

Further, when the change in the amount of decrease in plate thickness at the crack risk portion in each sample was obtained, the results shown in FIG. 12 were obtained.
As can be seen from FIG. 12, it was found that by reducing the angle α on the crack risk portion side, the amount of material flowing to the crack risk portion side was increased and the decrease in the plate thickness of the stretch flange portion 1C was suppressed. ..
In this way, it was found that the amount of material flowing to the crack risk portion side can be efficiently increased by reducing the bead angle in the direction in which the material is desired to flow.

1 Pressed parts 2 Adjusting part evaluation process 4 Main forming process 4A Second step 5 Straight line in the pressing direction 10 Metal plate 20 Excess thickness part 20A Cross section 21 First inclined part 22 Second inclined part P Adjusting part Y Excess thickness apex

Claims (11)

It is a manufacturing method of pressed parts that manufactures pressed parts by press-molding a metal plate.
When the metal plate is press-formed into the desired shape of the pressed part, the position in the stretch-deformable region that exceeds the preset stretch-deformation amount or the position where the compressive stress is desired to be increased is set as the adjustment unit.
As a press molding process for manufacturing the above pressed parts,
In the direction along the deformation direction of the elongation deformation, one or two or more surplus portions formed by being deformed in the plate thickness direction are formed with respect to at least one plate portion on both sides of the adjusting portion. 1 step and
The second step of crushing the excess meat formed in the first step and
A method for manufacturing a stamped part, which comprises. The cross section of the surplus portion along the deformation direction of the elongation deformation is on the side of the adjustment portion with respect to the surplus thickness apex when the position where the amount of deformation in the plate thickness direction is the largest is the surplus top. The method for manufacturing a pressed part according to claim 1, wherein the width is narrower than the width on the side opposite to the adjustment portion side. The cross section of the surplus portion along the deformation direction of the elongation deformation is formed on the adjustment portion side of the left and right sides, and the deformation amount in the plate thickness direction decreases toward the adjustment portion side with the first inclined portion. A second inclined portion is provided on both the left and right sides, which is formed on the side opposite to the adjusting portion and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion side.
The angle formed by the straight line connecting both ends of the first inclined portion and the straight line in the pressing direction in the second step is the straight line connecting both ends of the second inclined portion and the straight line in the pressing direction in the second step. The method for manufacturing a pressed part according to claim 1 or 2, wherein the angle is smaller than the angle formed. The method for manufacturing a pressed part according to any one of claims 1 to 3, wherein the surplus portion is formed by a bead or embossing. As the above-mentioned press forming process, a main forming process of forming into the part shape of the target pressed part is provided.
The method for manufacturing a pressed part according to any one of claims 1 to 4, wherein the main molding step and the first step are executed in one step. The method for manufacturing a pressed part according to any one of claims 1 to 5, wherein the adjusting portion is at a position where there is a possibility of cracking of the stretch flange. A metal plate for press forming into pressed parts.
When the metal plate is press-formed into the desired shape of the pressed part, when the position in the stretch-deformable region that exceeds the preset stretch-deformation amount or the position where the compressive stress is desired to be increased is set as the adjustment unit.
It has one or more surplus portions that are deformed in the plate thickness direction with respect to at least one plate portion on both sides of the adjusting portion in the direction along the deformation direction of the elongation deformation.
A metal plate for press molding, which is characterized by the fact that. The cross section of the surplus portion along the deformation direction of the elongation deformation is on the adjustment portion side with respect to the surplus thickness apex portion when the position where the amount of deformation in the plate thickness direction is the largest is the surplus thickness apex portion. The metal plate for press molding according to claim 7, wherein the width is narrower than the width on the side opposite to the adjustment portion side. The cross section of the surplus portion along the deformation direction of the elongation deformation is formed on the adjustment portion side of the left and right sides, and the deformation amount in the plate thickness direction decreases toward the adjustment portion side with the first inclined portion. A second inclined portion is provided on both the left and right sides, which is formed on the side opposite to the adjusting portion and the amount of deformation in the plate thickness direction decreases toward the side opposite to the adjusting portion side.
The angle formed by the straight line connecting both ends of the first inclined portion and the straight line in the plate thickness direction at the flat position is the angle formed by the straight line connecting both ends of the second inclined portion and the straight line in the plate thickness direction at the flat position. The metal plate for press molding according to claim 7 or 8, characterized in that it is smaller than. The metal plate for press molding according to claim 8 or 9, wherein the surplus portion is formed of beads or embossing. The metal plate for press molding according to any one of claims 7 to 10, wherein the surplus portion is crushed in the plate thickness direction.

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