CN109475911B

CN109475911B - Metal plate for press molding, method for manufacturing same, and method for manufacturing stamped part

Info

Publication number: CN109475911B
Application number: CN201780043209.8A
Authority: CN
Inventors: 中川欣哉; 山崎雄司; 藤井祐辅
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2016-07-15
Filing date: 2017-07-06
Publication date: 2021-06-25
Anticipated expiration: 2037-07-06
Also published as: KR20190015465A; JP6319529B1; JPWO2018012405A1; CN109475911A; WO2018012405A1

Abstract

Provided are a metal plate for press forming, which can improve formability more easily, and a method for manufacturing a stamped part using the metal plate. A metal plate (10) for press forming is press-formed into a final part shape, the metal plate (10) is formed into a shape of a concave-convex pattern (12), the shape of the concave-convex pattern (12) is one or more unit shapes (11) composed of curved shapes deformed in a plate thickness direction are repeatedly arranged in one or more directions along a plate surface. The unit shape (11) has a curved shape in which the height difference in the plate thickness direction is 3mm or more and the projection plane in the plate thickness direction is 400mm in terms of a square shape²Above 10000mm²The following.

Description

Metal plate for press molding, method for manufacturing same, and method for manufacturing stamped part

Technical Field

The present invention relates to a metal plate press-formed into a final component shape, and a method for manufacturing a stamped part by press-forming the metal plate into the final component shape.

Background

In the production of a part by press molding, improvement of the yield of the molded part and improvement of the moldability are important issues. In general, in order to improve the yield, it is preferable to set the molding conditions close to the stretch molding by reducing the amount of material flowing into the die as much as possible during the press molding.

However, if the material flow into the mold is too small, there is a problem that the thickness of the sheet becomes too thin in the molding region due to insufficient material in the mold during molding, and cracking occurs. On the other hand, if the forming of the drawing body is set to avoid the cracking, there is a possibility that the yield is lowered.

In order to cope with such a problem, various measures have been taken in the past. In general, it is known that, in press forming, formability is improved by forming in a plurality of stages of forming steps. This is because, in the case of molding in multiple stages, strain is not concentrated at one point but dispersed over the entire surface, as compared with the case of molding at once to the final part shape.

For example, patent document 1 discloses a method of designing a preform shape based on information of a sectional line length of a final part shape.

As a technique for improving the rigidity of a plate by providing a final member with an uneven pattern formed by embossing, techniques such as those described in patent documents 2 and 3 are disclosed, but the technical idea is different from the present invention.

Patent document 1: japanese patent No. 5867657

Patent document 2: japanese patent laid-open publication No. 2002-60878

Patent document 3: japanese laid-open patent publication No. 2012-45622

However, according to the technique described in patent document 1, although the effect of improving the formability can be obtained, it takes time to design a preform shape using CAE analysis.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a metal plate for press forming capable of improving formability more easily, and a method for manufacturing a stamped part using the metal plate.

In order to solve the need for both improvement in yield and improvement in moldability, the inventors of the present invention conducted investigation for effective preforming, and found the following: when the metal plate is formed in the main form while being pressed in a direction in which the unevenness of the uneven pattern disappears by previously imparting a shape in which the uneven pattern formed of the unit shape of the uneven pattern is repeatedly arranged to the metal plate, the entire metal plate portion of the area to which the uneven pattern is imparted is spread like opening a folded sheet, and as a result, strain is uniformly introduced over a wide range of the metal plate, and formability is improved.

In order to solve the above-described problems, one aspect of the present invention is a metal plate for press forming which is press-formed into a final part shape, the metal plate being at least partially formed into a shape of an uneven pattern in which one or two or more unit shapes including curved shapes deformed in a plate thickness direction are repeatedly arranged in one or two or more directions along a plate surface, the curved shape of the unit shape having a height difference in the plate thickness direction of 3mm or more and a projected area in the plate thickness direction of 400mm in terms of a square shape²Above 10000mm²The following.

According to the aspect of the present invention, when performing press forming, the formability when performing press forming into the shape of the final member can be improved and a high yield of the final member can be achieved by a simple configuration in which the shape of the uneven pattern composed of the repetition of the unit shapes is imparted to the metal plate in advance.

Drawings

Fig. 1 is a view illustrating a press-molding metal plate according to the present invention, in which fig. 1 (a) is a plan view and fig. 1 (b) is a cross-sectional view taken along line a-a' of fig. 1 (a).

Fig. 2 is a diagram illustrating another example of a press-molding metal plate according to an embodiment of the present invention.

Fig. 3 is a schematic diagram for explaining an example of a method for manufacturing a metal plate for press molding.

Fig. 4 is a schematic diagram for explaining a method of manufacturing the stamped part.

Fig. 5 is a diagram showing an example of a unit shape in the embodiment.

Fig. 6 is a diagram showing an example of setting the concave-convex pattern in the embodiment.

Detailed Description

Next, embodiments of the present invention will be described with reference to the drawings.

< Metal plate for Press Molding 10>

The metal plate 10 of the present embodiment is a press-molding metal plate that is press-molded into a final component shape. The material of the metal plate 10 is stainless steel, other steel materials, aluminum material, or the like.

As shown in fig. 1, the metal plate 10 of the present embodiment is formed in the shape of an uneven pattern 12, and the uneven pattern 12 is formed by repeatedly arranging a plurality of unit shapes 11 each including a curved shape deformed in the plate thickness direction, in two directions along the plate surface. In fig. 1, the case where the unit shapes 11 are arranged in two directions is exemplified, but the unit shapes 11 may be arranged in one direction or three or more directions. In addition, the concave-convex pattern 12 may be formed by combining a plurality of types of unit shapes.

The position of forming the uneven pattern 12 may be formed on the entire surface of the metal plate 10, but as shown in fig. 2, the shape of the uneven pattern 12 may be given only to the central portion of the punching position of the blank for punching. The uneven pattern 12 may be disposed at a predetermined interval in the longitudinal direction and the width direction of the plate regardless of the pressing position. Preferably, the uneven pattern 12 is formed on 50% or more of the surface of the metal plate 10.

Further, the regions in which the uneven pattern 12 is formed at 2 or more positions may be set for each unit area (each region where one pressing is performed), and individual uneven patterns may be formed.

The curved shape of the unit shape 11 is preferably a shape in which the entire surface is formed of a smooth surface (a surface having no portion with a steep curvature) and is smoothly connected to the adjacent unit shape 11. That is, the shape of the concave-convex pattern 12 is preferably set to a shape along the surface direction of the plate without a portion where the curvature is steeply changed (curvature steeply-changed portion). If the connection is not smooth, the uneven portion becomes an abnormal point, and during press forming, although the degree of steepness of the curvature steeply-varying portion depends, there is a possibility that strain is concentrated on the curvature steeply-varying portion to cause cracking. If the unit shapes 11 are connected smoothly to the adjacent unit shapes 11, the projection shape of the unit shape 11 in the press direction may be a quadrangle, a triangle, or an arbitrary geometric shape.

When a gap region that cannot be connected is formed between adjacent unit shapes 11, unit shapes 11 of other shapes for connecting the gap region may be interposed. However, it is preferable that the contour of the uneven pattern 12 has as few curvature steepness portions as possible. The curvature steeply changing portion has a sharp shape such as an L-shaped corner shape.

The curved shape of the unit shape 11 is set such that the height difference h in the plate thickness direction is 3mm or more and the projected area in the plate thickness direction is 400mm in terms of a square shape²Above 10000mm²Within the following ranges.

Here, the thickness t of the metal plate 10 is preferably 2mm or less, and more preferably 1mm or less, for example. In the metal plate 10 having such a thickness, the shape of the uneven pattern 12 can be imparted more reliably.

< method for producing Metal plate 10>

The method of manufacturing the metal plate 10 provided with the uneven pattern 12 may be, for example, as shown in fig. 3, a method of rolling the metal plate 1 finish-rolled by the rolling mill 21 by a pair of rolling rolls 20 having the uneven pattern 12 formed on the peripheral surface thereof, and transferring the uneven pattern 12 from the rolling rolls 20 to the metal plate 10. Further, although the transfer concave-convex pattern may be formed on both of the pair of rolling rolls 20, the transfer concave-convex pattern may be formed on only one of the rolling rolls 20 in advance, and the other rolling roll 20 may be a rubber roll having a rubber surface.

The rolling rolls 20 to which the uneven pattern is transferred may be applied to leveling rolls of a tension leveler or the like. The uneven pattern 12 may be transferred to the metal plate 10 by means other than the rolling rolls 20. For example, the uneven pattern 12 may be transferred by press forming using a metal mold.

< Press Molding into final part shape Using Metal plate 10 and others >

In the case of performing the stretch forming, when the metal plate 10 is formed into the final part shape at one time, the material is hardly strained by the frictional resistance at the punch bottom portion, but the material becomes excessively thin at the punch shoulder portion and the die shoulder portion, and the possibility of occurrence of cracking becomes high. Therefore, by introducing strain into the punch bottom in the final part shape in advance in the preforming step, the formability in the final forming step can be improved in a pseudo manner. Preferably, the direction of introduction is uniform over the whole.

In the present embodiment, as shown in fig. 4, the metal plate 10 for press forming to which the uneven pattern 12 composed of the repetition of the unit shapes 11 as described above is applied is press-formed into a final part shape using the upper die 30 and the lower die 31. In fig. 4, the case of the drawing is illustrated, but the metal plate 10 for press forming of the present embodiment may be formed by deep drawing or other press forming to be processed into a desired final member shape.

When the metal plate 10 is press-formed, the material to which the uneven portions are applied spreads like opening the paper folding, and therefore, the strain is uniformly introduced. As a result, strain is uniformly introduced into the material over a wide range in the plate portion to which the uneven pattern 12 is provided, and as a result, formability is improved. That is, in the press molding, the unevenness of the uneven pattern 12 extends like the spread of the folded paper, and thus, an excessive reduction in the sheet thickness can be suppressed, and the moldability can be improved.

At this time, the shape previously given to the metal plate 10 is a simple molded shape composed of a repetition of the unit shapes 11. It is preferable that the entire surface formed by the uneven pattern 12 is a smooth curved surface (may include a flat surface in part). According to this structure, it is possible to reliably prevent the strain from concentrating when the sheet is pressed.

Here, the reason why the bent shape of the unit shape 11 is a shape in which the height difference in the plate thickness direction is 3mm or more is because, if the height difference is not 3mm or more, the amount of the concave-convex after punching extending in the lateral direction like the folded paper is small, and the contribution rate to the uniformization of the strain is small. The upper limit of the height difference in the plate thickness direction is limited by the forming limit of the metal plate 10, but is preferably 10mm or less.

The projected area in the plate thickness direction (pressing direction) was set to 400mm in terms of a square shape²Above 10000mm²The following range is also a contribution rate in consideration of uniformity of the strain.

Here, the final product of the press is assumed to be a member having a length of at least 1m in the longitudinal direction, such as a panel, a frame of a building, or a wall of an automobile.

The unit of the projected area in the plate thickness direction of the unit shape 11 is mm²A0 (1), wherein the surface area of the unit shape 11 is expressed in mm²In the case of a1, it is preferable that at least one of the formulae (1) and (2) is satisfied.

A1＜A0×(1+ε0)²…(1)

A1＜(A0×t0)/t1…(2)

Wherein the content of the first and second substances,

ε 0: the uniform elongation limit of the metal sheet, and is dimensionless,

t 0: the initial thickness of the metal sheet, in mm,

t 1: the minimum sheet thickness in the final part shape is in mm.

In the formula (1), when a1 exceeds the upper limit (right item), there is a possibility that the portion stretched in the unit shape 11 will be reduced in diameter and broken. In the formula (2), when a1 exceeds the upper limit (right term), the thickness of the portion drawn in the unit shape 11 may be too small.

In the case of a plate to which the final part shape to be applied is determined, the concave-convex pattern 12 is preferably set to: in the area (size) of the blank to be pressed, the surface area of the metal plate 10 is equal to or less than the surface area in the final part shape, and is particularly smaller than the surface area in the final part shape. In this case, since the surface area of the metal plate 10 (blank) to which the uneven pattern 12 is applied is the same as or smaller than the surface area in the final part shape, no excess material is left in the die during press forming, and the unevenness of the uneven pattern 12 is stretched as in the case of folding and spreading, thereby forming the final part shape.

On the other hand, in the case where the surface area of the metal plate 10 is set to be larger than the surface area in the final part shape in the area (size) of the blank to be pressed, the uneven shape of the uneven pattern 12 may slightly remain after the final forming by press forming. In this case, although the shape accuracy of the final part shape is poor, effects such as improvement in rigidity and heat dissipation can be expected by the uneven shape with respect to the final part shape.

In addition, when the surface area of the metal plate 10 is a0 and the surface area of the final member shape is a1 in the area (size) of the blank to be pressed, the following expression is preferably satisfied. When this condition is satisfied, the sectional line length of the final part shape is set to be approximately the same as the sectional line length of the metal plate 10 as the blank in the same section.

|A1-A0|≤0.1×A1

Here, when manufacturing the metal plate 10 by rolling as the dedicated metal plate 10 to be punched out into a predetermined final part shape, the strain is more easily introduced uniformly by deforming the metal plate 10 as follows: the more the region of the plate in which a large amount of strain is introduced when the metal plate 10 in a state in which the uneven pattern 12 is not formed is press-formed into a target final part shape, the more the uneven pattern 12 is formed with a large height difference.

In this case, when there is a portion to be secured in rigidity (a portion where the thickness is not to be reduced) such as a portion receiving a load from another member as a product, the concave-convex pattern 12 may not be formed in the portion, that is, the first region where the rigidity is relatively secured in the final member shape. In this case, in the formation region where the uneven pattern 12 is formed, the uneven pattern 12 is elongated (the material spreads in the surface direction) and strain is easily introduced, as compared with the non-formation region where the uneven pattern 12 is not formed, so that the reduction in the plate thickness in the non-formation region can be suppressed, and the excessive reduction in the plate thickness in the formation region can also be suppressed by the uneven pattern 12.

In this way, even in the metal plate 10 dedicated for press forming into a predetermined product, the portion to be introduced with uniform strain can be easily controlled.

In the case where the final member shape is, for example, a semi-cylindrical shape, since the material only needs to be elongated mainly in the circumferential direction, the shape of the uneven pattern 12 which undulates only in the circumferential direction in which the strain is introduced may be provided to the metal plate 10.

[ examples ] A method for producing a compound

< example 1 >

First, embodiment 1 will be explained.

The unit shape 11 is designed by setting the following requirements so that the preform can be preformed by pressing and the effect of strain dispersion can be sufficiently obtained by main forming.

(1) The whole concave-convex surface is composed of smooth curved surfaces;

(2) smoothly connected to the adjacent unit shape 11;

(3) an increase in line length in all directions can be achieved for a plane.

The unit shape 11 of the present embodiment has a square shape as a projection in the plate thickness direction (press direction). The curved shape of the unit shape 11 is a shape in which the central portion is shifted by 90 degrees from the central phase at the side positions of the unit shape 11 by setting the profile in the direction parallel to one side of the square (referred to as the reference direction) to a sinusoidal shape of a single wavelength in which the central portion is recessed deepest, and continuously shifting the phase of the sinusoidal shape from this position to the direction orthogonal to the reference direction. Fig. 5 shows an example of the unit shape 11.

The unit shapes 11 thus designed are arranged in both the X direction and the Y direction so that the sides thereof are connected to each other, thereby forming the uneven pattern 12, and thus adjacent unit shapes 11 can be smoothly connected to each other.

In this case, in order to eliminate the directionality of deformation in the main molding, as shown in fig. 6, the uneven pattern 12 is designed so as to be sequentially arranged in the arrangement direction while sequentially rotating and displacing the arrangement of the unit shapes 11 by 90 degrees.

In this way, the uneven pattern 12 can be designed.

< example 2 >

Next, embodiment 2 will be explained.

When the uneven pattern 12 is designed to be formed by repeating the unit shapes 11 shown in example 1, the uneven patterns of examples 1 to 5 and comparative examples 1 to 6 are designed by changing the amplitude and the length of one wavelength in the sinusoidal shape of the unit shape 11. Table 1 shows a projected area a0, a difference in height in the sheet thickness direction, and a relationship (determination formula) between the above expressions (1) and (2) in each example and each comparative example.

In examples 1 and 2 and comparative examples 1 to 3, a metal plate 10 for press forming in which various kinds of uneven patterns 12 were transferred to a metal plate was manufactured by press forming a metal plate using an upper die and a lower die having a designed uneven pattern on a processing surface. In examples 3 to 5 and comparative examples 4 to 6, the metal plate 10 for press forming was manufactured by rolling the metal plate with a pair of rolling rolls 20 having a designed uneven pattern on the surface thereof and transferring the uneven pattern 12 to the metal plate.

Then, a square shape having a width of 200mm and a length of 200mm was cut out from the metal plate 10 in which no crack occurred at the time of transfer, and the cut square shape was used as a blank. Then, the final part shape is press-formed using the upper die 30 and the lower die 31 shown in fig. 4. At this time, the drawing was carried out to obtain a cylinder having a punch diameter of phi 150mm and a punch R of 5 mm. When the determination formula is used, the minimum plate thickness t1 is determined to be 0 when the crack occurs.

The evaluation results of the examples and comparative examples are also shown in table 1.

The rate of occurrence of cracks relative to the number of times of molding of the part, i.e., the fraction defective was evaluated.

The evaluation of the defect rate is as follows.

Very good: the reject ratio is less than 3 percent

O: the reject ratio is more than 3 percent and less than 5 percent

X: the defective rate is more than 5%

[ TABLE 1 ]

As is understood from table 1, in comparative example 1, since the difference in height between the projected area a0 and the thickness direction is small under the above conditions, the plate material is reduced in diameter, and the plate thickness is excessively small, so that breakage frequently occurs. In comparative example 2, since the difference in height in the plate thickness direction with respect to the projected area a0 was too large, the ductility of the plate material was insufficient when the uneven pattern 12 was transferred, and cracking occurred frequently.

In comparative examples 3 to 4, since the difference in height in the thickness direction is small, the thickness of the plate is too small due to the diameter reduction of the plate material in comparative example 3, and the fracture frequently occurs, while the fracture frequently occurs in comparative example 4, in the production of the final member.

In comparative examples 5 to 6, the projected area a0 was set large, but in comparative example 5, the difference in level in the plate thickness direction was small, and therefore, cracking occurred frequently during the production of the final member, and in comparative example 6, the difference in level in the plate thickness direction was too large, and cracking occurred frequently during the transfer of the uneven pattern 12.

In contrast, in examples 1 to 3, the uneven pattern 12 was transferred and the final member was manufactured with less occurrence of cracks and an excessively small plate thickness. Particularly, the defective rate was low in examples 2 to 3.

In addition, examples 4 to 5 are examples in which the projected area a0 was set to be large, as in comparative examples 5 to 6, but in examples 4 to 5, cracking occurred during transfer of the uneven pattern 12 and production of the final member, and the sheet thickness was too small, and particularly in example 4, the defect rate was small.

As described above, in the case of producing the stamped part by the production process of the metal plate 10 and the final member as in embodiment 2, the bent shape of the unit shape is preferably designed to be: the height difference in the plate thickness direction is 3mm or more, and the projected area in the press direction is 400mm in terms of a square shape²Above 10000mm²The following formula (1) or (2) is satisfied. It is found that the design is particularly preferable to satisfy both the above-mentioned formulas (1) and (2).

The present application claims priority from 2016 in Japanese patent application No. 2016-.

While the present invention has been described with reference to a limited number of embodiments, the scope of the claims is not limited thereto, and it will be apparent to those skilled in the art that modifications of the embodiments based on the above disclosure are possible.

Description of the reference numerals

10 … metal sheets; 11 … unit shape; 12 … relief pattern; 20 … rolling rolls; 21 … rolling mill; h … difference in height.

Claims

1. A metal plate for press molding, which is press-molded into a final part shape,

the metal plate for press molding is characterized in that,

at least partially formed in a shape of a concave-convex pattern in which one or two or more unit shapes composed of curved shapes deformed in a plate thickness direction are repeatedly arranged in one or two or more directions along a plate surface,

the unit shape has a curved shape with a height difference of 3mm or more in the plate thickness direction and a projected area of 400mm in the plate thickness direction converted to a square shape²Above 10000mm²The following，

The unit of the projected area in the plate thickness direction of the unit shape is mm²A0 wherein the unit of the surface area of the unit shape is mm²A1 satisfies the expression (1),

A1＜A0×(1+ε0)²…(1)

wherein the content of the first and second substances,

ε 0: the uniform elongation limit of the metal sheet and is dimensionless.

2. The metal plate for press molding according to claim 1,

the unit of the projected area in the plate thickness direction of the unit shape is mm²A0 wherein the unit of the surface area of the unit shape is mm²A1 satisfies the expression (2),

A1＜(A0×t0)/t1…(2)

wherein the content of the first and second substances,

t 0: the initial thickness of the metal sheet, in mm,

t 1: the minimum sheet thickness in the final part shape is in mm.

3. A method for manufacturing a metal plate for press molding according to claim 1 or 2,

the method for manufacturing a metal plate is characterized in that,

transferring the shape of the concave-convex pattern to a metal plate by using a rolling roller.

4. A method of manufacturing a stamping part for press-forming a metal plate into a final part shape,

the method for manufacturing a stamping is characterized in that,

the metal plate for press molding according to claim 1 or 2 is used as the metal plate for press molding.

5. A method of manufacturing a stamping according to claim 4,

when the metal plate is press-formed into the final part shape, the metal plate is deformed in a direction in which the unevenness of the uneven pattern given to the metal plate is reduced, and is formed into the final part shape while being deformed.

6. A method for manufacturing a stamping according to claim 4 or 5,

the surface area of the press-formed metal plate is equal to or less than the surface area in the final part shape.