KR102199309B1 - Press product manufacturing method - Google Patents

Abstract

It provides a press product manufacturing method that can more easily improve the moldability.
This is a method for manufacturing a pressed product in which the plate 10 is formed into the final part shape 12 by press molding.
A preforming step (1A) of preforming the plate 10 into a preformed shape to manufacture the intermediate part 11, and the main forming step (1B) of pressing the intermediate part 11 into a final part shape 12. Have.
In the preforming step 1A, at least a part of the forming region 20 by the main forming step 1B is used as the preforming region 20B, and with respect to the preforming region 20B, one direction along the plate surface Alternatively, it is preformed into an uneven pattern in which one or two or more unit shapes 15 formed of a curved shape deformed in the thickness direction toward two or more directions are repeatedly arranged.
In the main molding step 1B, press-molding is performed in a direction in which the irregularities of the irregularities pattern become smaller.

Description

Press product manufacturing method

The present invention relates to a method for manufacturing a press product in which a plate material is molded into a final part shape by a press forming process of two or more steps. The plate material is preferably a steel plate, an aluminum plate, or other metal plate, but a plate material made of a non-metal material may be used.

In the production of parts by press molding, improvement in the yield of the molded product and improvement in formability are important issues. In general, in order to improve the yield, it is desirable to reduce the amount of the material flowing into the mold during press molding as possible, and to set the molding conditions close to protruding molding.

However, if the inflow of the material into the mold is too small, the material in the mold becomes insufficient at the time of molding, so that the plate thickness becomes excessively thin in the molding area, and a defect such as cracking occurs. On the other hand, in order to avoid cracking, if the drawing main body is molded, there is a concern that the yield may decrease.

In order to cope with this defect, various measures have been taken in the past. In general, when performing press molding, it is known that the formability is improved by performing molding in a multi-step molding process. This is because, compared to the case where the molding is performed to the final shape at one time, the case where the molding is performed in multiple steps is because the deformation is not concentrated in one place but is dispersed as a whole.

For example, Patent Document 1 discloses a method of designing a preformed shape based on information on the length of the cross-sectional line of the final shape.

Here, as a technique for increasing the rigidity of the plate by giving a concave-convex pattern made of an emboss to the final part, a technique as described in Patent Literature 2 and Patent Literature 3 has been disclosed, but the technical idea is different from the present invention.

Patent Document 1: Japanese Patent No. 5867657 Publication Patent Document 2: Japanese Unexamined Patent Publication No. 2002-60878 Patent Document 3: Japanese Unexamined Patent Publication No. 2012-45622

However, in the technique described in Patent Document 1, although the effect of improving the moldability is obtained, it takes time to design a preformed shape using CAE analysis.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a pressed product that can more easily improve moldability.

In order to simultaneously solve both demands for improvement in yield and improvement in formability, the inventors conducted research and research to effectively preform, and in the preforming step, preformed into uneven patterns in which unit shapes made of irregularities are repeatedly arranged. When the uneven pattern is pressed in the direction in which unevenness of the uneven pattern disappears, the material in the region to which the uneven pattern is applied is unfolded in a form of unfolding the folded paper. The knowledge was obtained that deformation was uniformly introduced over a wide range and moldability was improved.

And in order to solve the problem, one aspect of the present invention is a press product manufacturing method for forming a plate material into a final part shape by press molding, wherein the plate material is preformed into a preform shape to manufacture an intermediate part. It has a pre-molding process and a main-forming process of press-forming the intermediate part into the final part shape, wherein the pre-forming process includes at least a part of the molding area by the main-forming process as a pre-forming area, The preforming area is preformed into an uneven pattern in which one or two or more unit shapes formed of a curved shape deformed in the thickness direction toward one or two or more directions along the plate surface are repeatedly arranged, and the main molding The process is characterized in that the shape of the final part is formed while deforming in a direction in which the irregularities of the irregularities pattern become smaller.

According to an aspect of the present invention, when press molding is performed, it is possible to improve the formability in the main molding and to achieve a high yield by simply preforming into a simple preformed shape that is formed by repeating unit shapes. .

1 is a diagram showing a molding process according to an embodiment based on the present invention.
2 is a diagram showing an example of the shape of a final part in a modified example.
3 is a diagram showing an example of a preformed area in a modified example.
4 is a diagram showing the shape of a final part in an example.
5 is a diagram showing a preforming area in an example.
6 is a diagram showing a unit shape in an example.
7 is a diagram illustrating an example of an uneven pattern in an example.
8 is a diagram explaining a preforming process in Examples.
9 is a diagram for explaining a main molding process in Examples.

In the case of elongation molding, if the single-circuit plate is molded into the final part shape, the material is hardly deformed due to frictional resistance at the bottom of the punch, but the material becomes excessively thin at the punch shoulder or die shoulder, and cracks. The likelihood of this occurring increases. Therefore, by introducing a strain into the bottom of the punch in the shape of the final part in the pre-molding step, it is possible to improve the formability in the final molding step by pseudo-shaping. Since it is preferable to put the deformation uniformly as a whole, it is preferable that the preforming is preformed so that the deformation easily becomes uniform in the main molding.

In the molding method of the embodiment based on the present invention, deformation is introduced by imparting a preforming shape made of an uneven pattern to at least a part of the material during preforming, and the folded paper is unfolded in the subsequent main forming step. By unfolding in a pattern, it is possible to suppress an excessive decrease in the plate thickness and improve the formability. In addition, in the molding method of the embodiment based on the present invention, it is also possible to simply set a region in which deformation is uniformly entered as a whole.

In the uneven pattern, deformation can be uniformly introduced as a whole by setting the uneven pattern in the same unit shape over the entire molding area in the main molding. When it is desired to introduce the deformation more uniformly, a unit shape having a larger height difference may be applied to a region where deformation is more difficult. For example, in the case of employing the elongated molding, considering that the deformation at the bottom of the punch is small, the uneven pattern is preformed only in the area abutting (adjacent) to the punch bottom, or when forming the uneven pattern over the entire molding area , The height difference of the uneven pattern formed in the area abutting the punch bottom is set relatively large. As described above, in this embodiment, it is possible to easily and uniformly control the deformation over a wide range.

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

In this embodiment, a case where the plate material is steel, other steel material, or aluminum plate is assumed and described.

<Configuration>

The press product manufacturing method of the present embodiment is a press product manufacturing method in which a plate material is formed into a final part shape by press molding in at least two steps (two steps). Specifically, as shown in FIG. 1, the press product manufacturing method of this embodiment has a pre-molding process (1A) and a main molding process (1B). You may perform a preliminary press forming step before the preforming step 1A. In this case, the material after preliminary press forming is a plate material to be subjected to the preforming step 1A. The plate material is, for example, a plate material having a thickness of 2 mm or less.

The preforming step (1A) is a step of preforming a plate material into a preforming shape to manufacture an intermediate part. The main molding step 1B is a main molding step of press-forming an intermediate part into a final part shape. You may have another step of further press-forming the part in the shape of the final part.

<Pre-molding process>

In the preforming step 1A, at least a part of the forming area processed by press forming by the main forming step 1B is used as a preforming area, and for the preforming area, one or two directions along the plate surface Towards the above, press-molding is performed into a shape of an uneven pattern formed by repeating and arranging one or two or more unit shapes made of a curved shape deformed in the plate thickness direction a plurality of times. The preforming region may be set to a region in which deformation is to be introduced among the forming regions in the main molding step 1B. Further, two or more preformed regions may be provided, and individual uneven patterns may be formed in each.

This preforming step may be performed when the blank is cut out from the plate material. For example, it may be transferred by forming a concave-convex pattern on the surface of the pressing tool that presses the plate.

Here, it is preferable that the uneven pattern is set so that the surface area in the preform shape becomes smaller than the surface area in the final part shape, particularly less than the surface area in the final part shape, in the preforming region. In this case, in the preforming area, since the surface area of the portion to which the concave-convex pattern is applied is the same or smaller than the surface area in the shape of the final part, material is not left at least in the preforming area in the mold during main molding, The unevenness of the applied uneven pattern is unfolded in a form in which the folded paper is unfolded, resulting in a final part shape.

On the other hand, when the uneven pattern is set so that the surface area in the preform shape is larger than the surface area in the final part shape in the preforming region, the unevenness applied at the time of preforming after the final molding by the main molding step (1B) The shape remains slightly. In this case, the shape accuracy of the final part shape is inferior compared to the case where the surface area in the preform shape is set to be smaller than the surface area in the final part shape, but effects such as improvement in rigidity and heat dissipation can be expected due to the uneven shape. have.

In the preforming region, when the surface area in the preform shape is A0 and the surface area in the final part shape is A1, it is preferable to satisfy the following equation. Under this condition, in the same cross-section, it is set so that the cross-sectional line length of the final part shape and the cross-sectional line length of the preformed shape are the same.

|A1-A0|≤0.1×A1

In addition, it is preferable to set the curved shape of a unit shape so that the difference in height difference in a plate|board thickness direction may be 3 [mm] or more. The upper limit of the difference in height in the thickness direction is automatically limited from the regulations of other factors.

In addition, as for the unit shape, it is preferable that the projected area in the pressing direction is 400 [mm ² ] or more and 10000 [mm ² ] or less in terms of a square shape. That is, when the projection shape in the pressing direction of the unit shape is a square shape or an almost square shape, it is preferable that one side of the square is in the range of 20 to 100 [mm].

In addition, when the projected area of the unit shape in the pressing direction is A0 [mm ² ] and the surface area of the unit shape is A1 [mm ² ], at least one of equations (1) and (2) is satisfied. desirable.

A1<A0×(1+ε0) ² ···(1)

A1<(A0×t0)/t1 ...(2)

here,

Uniform elongation limit of plate: ε0[dimensionless quantity]

Initial plate thickness of plate: t0[mm]

Minimum plate thickness in final part shape: t1[mm]

To

Here, in Equation (1), when A1 exceeds the upper limit (the right term), a constricted portion occurs in the elongated portion in the unit shape, and there is a possibility of fracture. In Equation (2), when A1 exceeds the upper limit (right term), there is a fear that the plate thickness of the elongated portion in the unit shape becomes too small.

In addition, it is preferable that the unit shape is formed of a mold having a shape that is smoothly connected to the adjacent unit shape, and is composed of a surface having a smooth surface (a surface having no sharp curvature portion) in contact with the material. That is, it is preferable to set the shape of the concave-convex pattern so that it is a shape along the surface direction, and there is no part (curvature steep part) with a sharp curvature. When it is not connected smoothly, the portion becomes a singularity, and at the time of forming in the main molding step 1B, depending on the abrupt degree of the curvature steep portion, there is a fear that the deformation concentrates on the curvature steep portion and cracks occur. As long as it is smoothly connected to adjacent unit shapes, the projection shape of the unit shape in the pressing direction may be a square, a triangle, or any geometric shape.

When a gap region that cannot be connected between adjacent unit shapes is formed, a unit shape of another shape for connecting the gap regions may be interposed. However, it is preferable to set the profile of the uneven pattern so as not to have as much force or abrupt curvature as possible. The sharp curvature portion has a sharp shape such as an L-shaped prismatic shape.

<Operation and others>

In this embodiment, in the preliminary forming step 1A, a concave-convex pattern formed by repetition of a unit shape is applied to a portion where the deformation is to be uniformly applied. As a result of this, when the final part shape is pressed into the final part shape in the main molding step 1B by elongation molding or the like, the material of the uneven part provided by the preform is unfolded in the form of unfolding the folded paper, thereby uniformly introducing deformation. In this way, in the region to which the concave-convex pattern is provided, as a result of introducing a wide and uniform strain into the material, the moldability is improved.

At this time, when press-forming is performed, the design is also simplified because it is pre-molded into a simple pre-molding shape that is made by repeating unit shapes.

Here, it is preferable that the entire inner surface formed in the uneven pattern is formed of a smooth curved surface (a flat surface may be included in a part). According to this configuration, it is possible to reliably prevent the concentration of deformation in the region in which the uneven pattern is formed.

<modification example>

Here, in the case where it is desired to uniformly introduce deformation to the entire molding region 20, preliminary molding may be performed so as to impart the uneven pattern to the entire molding region 20 according to the direction of the deformation to be introduced. However, as described above, the more the region where the deformation is to be introduced at the time of main molding, the more uniformly the deformation is easily introduced by setting it to an uneven pattern having a large difference in elevation.

In addition, if there is a part in the molding area 20 where rigidity is desired (a part where the plate thickness is not desired to be reduced), such as a part receiving a load from another part as a product, that part, that is, the final part In the first region 20A that is relatively rigid in the shape 12, it is sufficient not to form the uneven pattern. For example, in the case where a region 12A (first region 20A) that does not want to reduce the plate thickness is set in the center of the top and bottom in the final part shape 12 as shown in FIG. As shown in 3, so as not to form an uneven pattern in the portion corresponding to the first region 20A of the plate 10, only the second region (hatched portion in FIG. 3) of the forming region 20 is uneven. Just form a pattern. Further, some uneven patterns may be formed in a part of the first region 20A.

In this case, the preformed region 20B (the second region) in which the uneven pattern is formed is more deformed than the first region 20A in which the uneven pattern is formed (since the material is spread out in the plane direction). Since it is easy to be introduced, it is possible to suppress a decrease in the plate thickness in the first region 20A, and it is also possible to suppress an excessive decrease in the plate thickness in the preform region 20B by the uneven pattern. Here, of the shaping region 20, other than the first region 20A becomes the second region 20B.

As described above, in the present embodiment, it is also possible to easily control the portion in which uniform deformation is to be introduced.

In addition, when the final part shape 12 is, for example, a semi-cylindrical shape, the material needs to be mainly elongated in the circumferential direction, so if it is set to a shape of an uneven pattern that is a wave shape only in the circumferential direction in which the deformation is introduced. do.

In addition, the preformed region may be set only in a part of the region in the plate material corresponding to the molding region in the main molding.

Example

<First Example>

First, a description will be given of the first embodiment.

In the first embodiment, a case where the final part shape 12 is a cylindrical shape as shown in Fig. 4 is described as an example.

In this first embodiment, as shown in Fig. 5, the shape of the concave-convex pattern in which the unit shapes 15 are repeatedly arranged two-dimensionally over the entire forming area 20 in the main forming step 1B is formed.

Here, in order to be able to preform by pressing and to sufficiently obtain the effect of strain dispersion due to the preform in main molding, the following requirements were set and the unit shape 15 was designed.

(1) All the insides of the surface in the preformed region 20B are formed of smooth curved surfaces.

(2) It is smoothly connected with the adjacent unit shape 15.

(3) It is possible to increase the length of the line in all directions with respect to the plane.

In the unit shape 15 of the present example, the projection shape in the press direction was a square. The curved shape of the unit shape 15 is set to a profile of a direction (referred to as the reference direction) that passes through the center and is parallel to one side of the square (referred to as the reference direction), and has a sine curve shape corresponding to one wavelength, with the center being the most recessed. , The phase of the sine curve was continuously shifted from the position to the direction orthogonal to the reference direction, and the phase was set to shift 90 degrees from the side position of the unit shape 15 to the center. . An example of the unit shape 15 is shown in FIG. 6.

By connecting the sides of the designed unit shape 15 and forming an uneven pattern in parallel in two directions in the X and Y directions, it becomes possible to smoothly connect adjacent unit shapes.

At this time, in order to cancel the directionality of deformation in the main molding, as shown in Fig. 7, the uneven pattern was designed so that the unit shapes 15 were sequentially arranged in the alignment direction while rotatingly displaced by 90 degrees.

And, as shown in FIG. 8, by press-molding the plate 10 with the upper mold 31 and the lower mold 32 having the uneven pattern on the processing surface, the plate material 10 is preformed into a preformed shape, and the intermediate part 11 To manufacture (pre-molding process (1A)). In addition, in the Example, in the preformed region 20B, the surface area in the preformed shape and the surface area in the final part shape 12 were set equally.

Next, as shown in FIG. 9, using the die 33 and the punch 34 for cylindrical elongation molding, the preformed intermediate part 11 is press-formed into the final part shape 12. (Main molding process (1B)). Here, a punch diameter of 150 mm? and a punch R were formed into a 5 mm cylindrical elongate molding.

In addition, as a comparative example, a product was produced by performing only the main molding step (1B) without separately performing preforming.

Further, as determined about the limit molding height, the examples based on the present invention had a limit molding height of about twice as compared to the comparative example. Thus, compared with the case of the comparative example of one-time molding, it was confirmed that a sufficiently high formability was obtained in the example based on the present invention.

<Second Example>

Next, a second embodiment will be described.

In this second embodiment, for each of the examples and each comparative example, under the same conditions as in the first embodiment, two steps of a preliminary forming step (1A) and a main forming step (1B) are performed under the same conditions as in the first embodiment. Thus, each press product (final part) was manufactured. However, each of the uneven patterns in Examples 1 to 5 and Comparative Examples 1 to 6 was designed by changing the amplitude and the length for one wavelength, respectively, of the sinusoidal shape in the unit shape 15 to be adopted.

In Table 1, the projection area A0 in each Example and each comparative example, the height difference in the plate thickness direction, and the relationship (decision formula) between the above-described formulas (1) and (2) are described. In addition, when using the determination formula, when fracture occurred, it was determined by setting the minimum plate thickness t1 to 0.

In addition, in Table 1, the evaluation results of each Example and Comparative Example are also described.

In the evaluation, the defective rate, which is the ratio at which cracks occur with respect to the number of times the parts are formed, was used.

The defective rate evaluation is as follows.

◎: Less than 3% defective rate

○: Defect rate 3% or more and less than 5%

×: defect rate of 5% or more

As can be seen from Table 1, in the method of manufacturing a pressed product under the above conditions, in Comparative Example 1, since the height difference between the projected area A0 and the plate thickness direction was small, a constricted portion was formed in the plate material and the plate thickness became too small. , Fracture was frequent. In addition, in Comparative Example 2, since the height difference in the plate thickness direction was excessive with respect to the projected area A0, the ductility of the plate material was insufficient at the time of manufacture of the intermediate part, and fracture was frequent.

In addition, in Comparative Examples 3 to 4, since the difference in height in the plate thickness direction was small, when the final part was manufactured, a constricted portion was formed in the plate material in Comparative Example 3, so that the plate thickness was too small and fracture was frequent, and in Comparative Example 4 There were frequent parts.

In addition, in Comparative Examples 5 to 6, the projected area A0 was provided wide, but in Comparative Example 5, the difference in height in the plate thickness direction was small with respect to the projected area A0, so fractures occurred frequently during manufacture of the final part, and in Comparative Example 6, the plate thickness The difference in elevation in the direction became excessive, causing frequent breakages in manufacturing intermediate parts.

On the other hand, in Examples 1 to 3, it was possible to manufacture without causing breakage during manufacture of intermediate parts and final parts, and without causing the plate thickness to become too small. In particular, in Examples 2 to 3, the defective rate was small.

In addition, Examples 4 to 5 are examples in which the projected area A0 is provided as wide as in Comparative Examples 5 to 6, but in Examples 4 to 5, breakage occurs during manufacture of intermediate parts and final parts, and the plate thickness is It is less likely to be excessive, and in particular, the defective rate is small in Example 4.

As described above, from the second embodiment, when manufacturing a press product by employing the manufacturing process of the intermediate part and the final part, the curved shape of the unit shape has a height difference of 3 [mm] or more in the plate thickness direction, and the press direction It can be seen that it is preferable to design so that the projected area of is not less than 400 [mm ² ] and not more than 10000 [mm ² ] in terms of a square shape, and also satisfies the above equation (1) or (2). In particular, it can be seen that it is more preferable to design to satisfy both equations of the above (1) and (2) equations.

As described above, the entire contents of Japanese Patent Application 2016-140696 (filed on July 15, 2016) for which the present application claims priority, constitute a part of the present disclosure by reference.

Here, although the description was made with reference to a limited number of embodiments, the scope of the rights is not limited thereto, and modifications of each embodiment based on the above disclosure are obvious to those skilled in the art.

1A preforming process
1B main molding process
10 plate
11 middle parts
12 Final part shape
15 units shape
20 shaping area
20A first area
20B preform area (second area)

Claims (5)

As a press product manufacturing method for forming a plate material into a final part shape by press molding,
It has a preforming process of preforming the plate material into a preformed shape to manufacture an intermediate part, and a main molding process of pressing the intermediate part into the final part shape,
In the preforming process, at least a part of the forming area according to the main forming process is used as a preforming area, and the preforming area is directed toward at least two directions along the plate surface, in a curved shape deformed in the thickness direction. Pre-molding into an uneven pattern in which one or two or more unit shapes formed are repeatedly arranged,
The main shaping process is formed into the final part shape while deforming in a direction in which the irregularities of the irregularities pattern are smaller,
The curved shape of the unit shape is characterized in that the height difference in the plate thickness direction is 3 [mm] or more, and the unit shapes adjacent to each other in the repetition direction are smoothly connected so that there is no part where the curvature is steep. Press product manufacturing method. The method according to claim 1,
The concave-convex pattern, in the preformed region, the surface area of the preformed shape is set to be less than the surface area of the final part shape. The method according to claim 1 or 2,
The shaping area by the main shaping process has a first area to ensure rigidity and a second area other than the first area,
In the preforming step, at least a part of an area of the plate material corresponding to the second area is used as the preforming area. The method according to claim 1 or 2,
In the curved shape of the unit shape, the height difference in the plate thickness direction is 3 [mm] or more, and the projected area in the press direction is 400 [mm ² ] or more and 10000 [mm ² ] or less in terms of a square shape. Product manufacturing method. The method according to claim 1 or 2,
When the projected area of the unit shape in the pressing direction is A0 [mm ² ] and the surface area of the unit shape is A1 [mm ² ], at least one of equations (1) and (2) is satisfied. Press product manufacturing method.
A1<A0×(1+ε0) ² ···(1)
A1<(A0×t0)/t1 ...(2)
here,
Uniform elongation limit of plate: ε0[dimensionless quantity]
Initial plate thickness of plate: t0[mm]
Minimum plate thickness in final part shape: t1[mm]
to be.

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