KR20160077426A - Apparatus and Method for press forming - Google Patents

Abstract

The present invention provides an apparatus and a method for press forming, which minimize deformation in a blanking process to enhance formability when a secondary forming process is performed; thereby enhancing a quality of a final product. According to the present invention, the apparatus for press forming comprises: a lower mold mounted on a press having an upper part to which materials are supplied; and an upper mold mounted on the press, having a lower part to which materials are supplied wherein the lower mold includes a lower inside die, a lower outside die holding the lower inside die in a hollow unit and spaced at regular distances from a circumference of the lower inside die to form a gap with the lower inside die, and the upper mold including a multi-stage punch provided with an insertion unit formed to be stepped and inserted into the gap and provided to make the materials pass through the gap by the insertion unit.

Description

[0001] Apparatus and Method for Press forming [0002]

The present invention relates to a press forming apparatus and a method.

Blanking and piercing, which are part of the technique of forming a blank using a die set coupled to a press and a press, can be performed by punch 2 and die 3, And pressurizing the work 1 using a holder 4 if necessary.

It is a piercing operation to press the material with a punch and die and use the material put on the die as a product, and the blanking operation is to use the material separated from the material put on the die by punch. Thus, conventional blanking and piercing operations can be performed within the same die set.

The material is separated by using punches and dies, and the amount of plastic deformation applied to the edge portion of the separated material becomes a factor for evaluating the secondary formability of the product. Particularly, since the formability of the edge portion of the product affects the quality of the finished product, it is very important to prevent cracking at the edge portion.

The formability of the edge portion may vary depending on the shape of the punch. Fig. 1B shows the result of the forming analysis when the punch 2 is formed with a flat bottom face as shown in Fig. 1A. The material 1 is subjected to more plastic deformation in the region separated by the punch, It can be seen that the deformation is concentrated in the blanking product.

On the other hand, as shown in FIG. 2B, the material formed by the punch 2 including the multi-end portion 2a as shown in FIG. 2A is subjected to deformation by the multi-end portion 2a in the blanking product, However, on the contrary, due to the tensile force applied to the material 1, fracture occurs at a relatively low shear strain (plastic deformation), and secondary formability can be improved.

An object of the present invention is to improve the quality of a final product by improving moldability during secondary molding by minimizing deformation in a press molding process, particularly in a blanking process.

Another object of the present invention is to provide a press forming apparatus which can be applied to various materials and a press forming method using the same.

The present invention provides a press forming apparatus and method.

First, a press forming apparatus according to the present invention comprises a lower mold mounted on a press machine and supplied with a material to an upper portion thereof; And an upper mold mounted on the press machine and supplied with a material to a lower portion thereof, wherein the lower mold includes a lower inner die; And a lower outer die received in the hollow portion to receive the lower inner die and spaced a distance from the outer periphery of the lower inner die to form a gap with the lower inner die, And a multistage punch provided with an insertion portion inserted into the gap and provided to allow the material to pass through the gap by the insertion portion.

Preferably, the multi-step punch includes a protruding region protruding downward from the one surface of the inserting portion contacting the workpiece at a predetermined height.

More preferably, the multi-stage punch includes a punch middle portion provided corresponding to the lower inner die, and the insertion portion may be disposed outside the punch middle portion.

More preferably, the multi-stage punch may be formed of a plurality of the inserts.

More preferably, the protruding region is provided at a distance from the outer periphery of the insertion portion in the direction of the center of the insertion portion, and the side portion may be inclined.

More preferably, the protruding region has a height value in a range of 0.3 mm or more and 1.0 mm or less, and is spaced apart from the outer periphery of the insertion portion by 1 mm or less at a contact surface with the insertion portion, And an inclination of 135 degrees or more.

More preferably, the upper mold includes an inner blank holder provided corresponding to the lower inner die; And an outer blank holder provided corresponding to the lower outer die, wherein the multi-stage punch is inserted between the inner blank holder and the outer blank holder so as to be lowered.

More preferably, the upper mold is connected to the multistage punch at the punch middle, and is provided to be in contact with the material before the insert.

More preferably, an elastic member may be provided between the holding member and the multi-stage punch.

More preferably, the multi-stage punch has an inclined insertion portion to form a shear angle in the material.

More preferably, the shear angle may be provided at a value in the range of greater than 0 degrees and less than 9 degrees.

On the other hand, the present invention as another aspect provides a press forming method.

First, a press forming method according to a preferred embodiment of the present invention is a method of punching a material by a punch and a die provided in an upper mold and a lower mold mounted on a press machine, Placing a non-forming region existing outside at a position corresponding to the upper mold and the lower mold; And a forming step of multi-stepping or cutting the material in the punch with a predetermined distance from the outer periphery of the forming area.

Preferably, the upper mold or the lower mold is provided with a gap corresponding to a region where the material is pressed or cut by the punch, and after completion of movement of the upper mold or the lower mold, And a region to be pressed or cut by the punch may be inserted or passed through the gap by the punch.

More preferably, the punch is provided with a protruding portion protruding at a predetermined height in the material direction on a surface contacting the work, and the protruding portion is brought into contact with a region to be pressed or cut by the punch Can be provided.

More preferably, the placing step comprises arranging the forming area of the blank material in a corresponding one of the blank holders mounted on the upper mold or the lower mold, and the forming step is a step of bringing the blank holder into contact with the blank holder have.

More preferably, the forming step includes the protrusions on the punch, wherein the protrusions are formed to have a height difference with respect to one surface of the material, and a predetermined inclination is formed between the protrusions on the basis of one surface of the material , And the material is subjected to multi-step pressing or cutting with the punch.

According to the present invention, the efficiency of the molding process can be increased, and the quality of the product to be molded can be improved.

Further, the plastic deformation at the front end face of the material subjected to the shearing process can be minimized, thereby increasing the secondary molding allowance of the material.

In addition, the protrusion of the punch imparts a tensile force to the material to reduce the shear load, thereby extending the service life of the device.

Therefore, it is possible to reduce the overall defect rate of the product and realize the effect of reducing the manufacturing cost.

1A schematically shows a configuration of a die set according to the prior art.
Fig. 1B is a result of molding analysis of a material molded by the die set shown in Fig. 1A.
2A schematically shows a configuration of a die set according to still another prior art.
Fig. 2B is a result of molding analysis of the material molded by the die set shown in Fig. 2A.
3 is a perspective view of a press forming apparatus according to a preferred embodiment of the present invention.
4 is a cross-sectional view of an upper mold and a lower mold according to a preferred embodiment of the present invention.
FIG. 5 is a schematic view illustrating a state of a workpiece formed by a press-molding die apparatus according to a preferred embodiment of the present invention.
6 is a detailed view of a multi-stage punch according to a preferred embodiment of the present invention.
7 is a cross-sectional view of an upper mold and a lower mold according to another preferred embodiment of the present invention.
8 is a cross-sectional view of an upper mold according to another preferred embodiment of the present invention.

In order to facilitate an understanding of the description of the embodiments of the present invention, elements denoted by the same reference numerals in the accompanying drawings are the same element, and among the constituent elements that perform the same function in each embodiment, Respectively.

Further, in order to clarify the gist of the present invention, a description of elements and techniques well known in the prior art will be omitted, and the present invention will be described in detail with reference to the accompanying drawings.

It is to be understood, however, that the spirit and scope of the present invention are not limited to the embodiments shown, but may be suggested by those skilled in the art in other forms, additions, or alternatives, .

3, the press forming apparatus according to the preferred embodiment of the present invention includes a lower mold 20 mounted on a press machine (not shown) and supplied with a material 1 at an upper portion thereof, And an upper mold 10 to which a material is supplied to the lower portion.

The lower mold 20 includes a lower inner die 21 and a hollow portion that houses the lower inner die and is spaced from the outer periphery of the lower inner die 21 by a predetermined distance, And a lower outer die (22) provided to form the lower outer die (22).

The upper mold 10 is provided with an insertion portion 11a which is provided at an end to be inserted into a gap 23 formed by the lower inner die 21 and the lower outer die 22, And a multi-stage punch (11) provided to allow the work (1) to pass through the gap (23).

The multistage punch 11 includes a punch middle portion 11c and the punch middle portion 11c is formed by an insertion portion 11a protruding at a predetermined height so as to surround the punch middle portion 11c in all directions .

However, the multi-stage punch 11 may be formed by machining the punch middle weights 11c in a single member, or may be formed by combining the plurality of insertion portions 11a to form the punch weights 11c.

3, the inserting portion 11a may be provided so as to surround the four sides of the punch middle portion 11c or may be provided in the insertion portion 11a in accordance with the characteristics of the material 1 to be processed or the characteristics of the product. It is also possible to change the number and apply it.

According to the form in which the insertion portion 11a is provided, the punch middle portion 11c may be provided in a closed form or in an open form, and is not limited to the present invention and may be appropriately selected by a person skilled in the art There is something.

An inner blank holder 12 and an outer blank holder 13 are provided between the multistage punch 11 and the blank 1 in order to suppress wrinkling during forming of the blank 1 and improve formability .

At this time, the inner blank holder 12 is provided at a position corresponding to the lower inner die 21 of the lower mold 20, and the outer blank holder 13 is arranged at a position corresponding to the lower outer die 22. [

4, the insertion portion 11a of the multi-stage punch 11 has a holder gap 14 formed by the inner blank holder 12 and the outer blank holder 13, and the lower inner die 21, And the gap 23 formed by the upper outer die 22 and the lower outer die 22 in a straight line.

Preferably, the size of the punch innerlayer 11c described above may be the same as the size of the hollow portion 22a of the lower outer die 22 in which the lower inner die 21 is received.

However, the sizes of the inner blank holder 12 and the outer blank holder 13 within the range of not covering or not covering the gap 23 formed by the lower inner die 21 and the lower outer die 22 are not limited to those skilled in the art It is possible to change it appropriately.

However, since the remaining material on the upper surface of the lower inner die 21 becomes a product after the lowering of the upper mold 10 in the blanking molding process, the size of the inner blank holder 12 is adjusted to the size of the lower inner die 21 If they are the same, the quality of the product can be improved. In consideration of this point, the inner and outer blank holders 12 and 13 can be designed in consideration of the shape of the blank 1 remaining on the lower mold 20 after the upper mold 10 descends.

When the inner and outer blank holders 12 and 13 are provided at the lower portion of the multistage punch 11 as described above, the height of the insertion portion 11a of the multistage punch 11 is determined by the height of the inner and outer blank holders 12 and 13 , The thickness of the material, and the height of the lower inner die 21 and the height of the lower outer die 22, respectively.

6 shows a multi-stage punch 11. Referring to this, it can be seen that the insertion portion 11a of the multi-stage punch 11 is provided with the protruding region 11b. The protruding region 11b is provided on the side where the insertion portion 11a contacts the work.

And a spacing distance 18 from the outer periphery of the insertion section 11a. The spacing distance 18 may be formed in the center of the insertion section. In addition, the side surface 17 may be inclined.

The protruding area may have a height value in a range of 0.3 mm or more and 1.0 mm or less. The spacing distance 18 may be a value of 1 mm or less, a slope angle of the side surface 17 (? 1) may have a value of 135 ° or more.

According to the protruding region 11b of the multi-stage punch 11 having the structure described above, the material existing in the gap 23 rather than the material existing on the upper surface of the lower inner die 21 in the material 1 shown in Fig. . Then, the work hardening due to deformation is also concentrated on the material existing in the gap 23.

Therefore, after the upper mold 10 is lowered, the state shown in FIG. 5 can be obtained. That is, the original material 1 includes a piercing material 1b remaining on the upper surface of the lower outer die 22, a blanking material 1a remaining on the upper surface of the lower inner die 21, The scrap 1c separated by the inserting portion 11a of the scraper 1c.

At this time, the work hardening is concentrated on the deformation area 1d of the scrap 1c and the deformation area 1d is removed together with the scrap 1c. Therefore, there is an effect that the piercing process and the blanking process can be performed at one time, and the region to be plastically deformed is concentrated in the deformation region 1d, and the scrap 1c can be removed together with the discharge.

The configuration of the multi-stage punch 11 may be modified and provided as shown in FIG. And the holding member 15 instead of the inner blank holder 12 is provided in the punching middle portion 11c. The holding member 15 is connected to the multi-stage punch in the punch middle, and is provided to come into contact first with the material than the insertion portion 11a.

At this time, since the multi-stage punch 11 and the holding member 15 start to descend together when the upper mold 10 starts to descend, in order for the holding member 15 to first come into contact with the work 1, The protruding region 11b of the holding member 11 and the lower surface of the holding member 15 should be provided so as to have mutual steps.

Then, the material 1 is first pressed by the holding member 15 before the front end face is formed by the multi-stage punch 11, so that the surface quality of the material can be improved.

The elastic member 16 may be provided between the holding member 15 and the multi-stage punch 11 in order to protect the upper mold 10 from the impact caused by the lowering of the repeated press machine. The elastic member 16 can be used as a normal spring, but this can be suitably changed and applied by the work environment and the operator. This makes it possible to prevent damage to the device and increase the life of the device.

On the other hand, the multi-stage punch 11 may be provided with the insertion portion 11a inclined as shown in FIG. That is, the protruding region of the insertion portion 11a disposed on one side and the protruding region of the insertion portion 11a disposed on the other side are provided with a step difference from each other. This can be implemented by providing different heights of the insertion portions 11a.

The multi-stage punch 11 is inclined as described above to form a shear angle? Providing a shear angle can reduce the shear load, reduce vibration and noise.

Accordingly, since the impact and the load applied to the press machine and the upper mold 10 can be reduced, the life of the apparatus can be prolonged, Plastic deformation can be minimized. Therefore, the work hardening due to plastic deformation is reduced, and the secondary molding allowance of the material is increased.

Preferably, the shear angle may range from greater than 0 degree to less than 9 degrees, but may be suitably varied depending on the thickness and material of the workpiece 1, and is not limited by the present invention.

On the other hand, the present invention as another aspect provides a press molding method capable of improving the quality of an edge portion of a work.

That is, a method of punching a material with punches and dies provided in an upper mold and a lower mold mounted on a press machine, wherein a forming region in the material and a non-forming region existing outside the outer periphery of the forming region, A placing step of placing the mold at a position corresponding to the mold; And a molding step of multi-pressing or cutting the material in the punch with a predetermined distance from the outer periphery of the molding area.

In particular, the upper mold or the lower mold may be provided with a gap corresponding to a region where the material is pressed or cut by the punch, and after completion of movement of the upper mold or the lower mold, The region to be pressed or cut by the punch may be inserted or passed through the gap by the punch.

The punch may be provided with a protruding portion protruding at a predetermined height in the direction of the material on a surface contacting the material, and the protruding portion may be provided in contact with a region to be pressed or cut by the punch . That is, when the punch descends, the protrusions provided on the punch come in contact with the workpiece first.

The forming step may include placing the forming area of the workpiece in a corresponding position on the blank holder mounted on the upper mold or the lower mold and bringing the blank holder into contact with the forming area, It is possible to prevent wrinkles and cracks by holding the blank holder in the material present in the forming region, and the quality of the edge portion after molding is further increased.

Hereinafter, a press forming method according to still another modified embodiment of the present invention will be described in addition to the press forming method according to the preferred embodiment of the present invention. It is to be understood, however, that modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined by the following claims.

First Embodiment

First, a method is used in which a material is pressed by an upper mold and a lower mold mounted on a press machine, and a blank is formed by generating a front end. In this method, a scrap area existing in an area other than the area set as the blanking molded article Wherein the scraping area is separated from the work by punching after the completion of the movement of the upper mold or the lower mold, And is located between the upper mold and the lower mold.

Second Embodiment

The present invention also provides a method of piercing a workpiece by pressing a workpiece with an upper mold and a lower mold mounted on a press machine to generate a shear, wherein a scrap area existing inside the area set as the pierced molded article is pierced, The method comprising: bringing a mold or a punch installed in the lower mold into contact with each other to form a blanking molded article in an area other than a region in contact with the piercing punch in the scrap area.

Third Embodiment

In addition, a method of pressurizing a material with an upper mold and a lower mold mounted on a press machine to generate a front end so as to finish blanking molding and piercing molding at the same time, wherein an area inside the area set as a piercing molded article is referred to as a blanking molded article Wherein the area between the pierced molded article area and the blanking molded article area is a scrap area and the scraped area is punched by the punching tool so that the scraped area is formed after the completion of the movement of the upper mold or the lower mold Is separated from the material.

The press molding method according to the first, second, and third embodiments may further include a step of providing a gap corresponding to the scrap region of the material on the upper mold or the lower mold, and moving the upper mold or the lower mold Thereafter, the scrap region may be provided to be inserted or passed through the gap by the punch.

The punch may be provided with a protruding region protruding at a predetermined height in the material direction on the surface contacting the material, and the protruding region may be provided in contact with the scrap region.

In addition, the quality of the upper mold and the lower mold contact surface of the blanking molded article may be improved by bringing the blank holder into contact with the area set as the blanking molded article in the blank.

The punch may be provided with a plurality of protruding regions, and the protruding regions may be provided to have a height difference with respect to one surface of the material, and a predetermined inclination may be formed between the protruding regions.

After the completion of the movement of the upper mold 10 or the lower mold, the material that has passed through the gap 23 by the multi-stage punch 11 becomes a scrap 1c. On the upper surface of the lower inner die 21, The remaining material becomes the blank material 1a. The material remaining on the upper surface of the lower outer die 22 may be the pierced material 1b. By doing so, the piercing process and the blanking process can be performed at the same time by lowering the upper mold 10 at one time, and the efficiency of the process can be increased.

In addition, the press forming apparatus and method according to the present invention can also be used for the purpose of performing the piercing process or the blanking process alone but improving the edge formability of the material (1).

For example, even if the lower inner die 21 is provided as shown in FIG. 5, the material la placed on the upper surface of the lower inner die 21 after the lowering of the upper mold 10 can be separated and discharged as scrap.

However, in this case, the moldability of the front end face of the pierced work 1b, that is, the edge portion can be improved and the strength can be ensured. On the contrary, the blanking process can be similarly applied.

Therefore, conventionally, it has been difficult to form ultra-high strength steel due to the increase of plastic deformation as the strength of the material increases, and it is also difficult to improve the formability. However, according to the present invention, It is possible to adjust the area appropriately and to obtain high moldability even in a steel material for automobiles having a tensile strength of 780 MPa or more and to improve the burring property of ultra high strength steel.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be apparent to those of ordinary skill in the art.

1: Material 10: Upper mold
20: Lower mold

Claims (16)

A lower mold mounted on the press machine and supplied with material to the upper portion; And
And an upper mold mounted on the press machine and supplied with a material to a lower portion thereof,
The lower mold,
A lower inner die; And
And a lower outer die received in the hollow portion to receive the lower inner die and spaced a distance from the outer periphery of the lower inner die to form a gap with the lower inner die,
The upper mold includes:
Wherein the insertion portion is provided to allow the material to pass through the gap and to generate shear in the material together with the lower mold;
And press-molding the press-molding die.
The method according to claim 1,
The multi-
And a protruding region protruding downward from the one surface of the inserting portion contacting the material at a predetermined height.
3. The method of claim 2,
The multi-
And the insert portion is disposed outside the punch middle portion so as to correspond to the lower inner die.
3. The method of claim 2,
The multi-
And the plurality of insertion portions are formed as a set of the insertion portions.
5. The method according to any one of claims 2 to 4,
The protruding region
The insertion portion being spaced apart from the outer periphery of the insertion portion by a predetermined distance in the center direction of the insertion portion,
And the side face is inclined.
6. The method of claim 5,
The protruding region
A height value in the range of 0.3 mm or more and 1.0 mm or less,
Wherein the insertion portion is spaced apart from the outer periphery of the insertion portion by 1 mm or less at a contact surface with the insertion portion,
And the side surface is provided to form an inclination of 135 degrees or more with the contact surface with the insertion portion.
5. The method according to any one of claims 1 to 4,
The upper mold includes:
An inner blank holder provided corresponding to the lower inner die; And
And an outer blank holder provided corresponding to the lower outer die,
The multi-
Wherein the insertion portion is inserted between the inner blank holder and the outer blank holder and is lowered.
The method of claim 3,
The upper mold includes:
A holding member connected to the multi-stage punch in the punch middle portion and provided to contact the material first than the insertion portion;
Further comprising: a pressurizing unit that pressurizes the pressurized gas.
9. The method of claim 8,
And an elastic member is provided between the holding member and the multi-step punch.
5. The method according to any one of claims 1 to 4,
The multi-
Wherein the insertion portion is inclined so as to form a shear angle in the material.
11. The method of claim 10,
The shear angle
Is in the range of more than 0 degrees and less than 9 degrees.
A method of punching a material by a punch and die provided in an upper mold and a lower mold mounted on a press machine,
A placing step of placing a forming region in the material and a non-forming region existing outside the outer periphery of the forming region at positions corresponding to the upper mold and the lower mold; And
A molding step of multi-stepping or cutting a predetermined distance from the periphery of the forming area in the material by the punch;
.
13. The method of claim 12,
Wherein the upper mold or the lower mold is provided with a gap corresponding to a region where the material is pressed or cut by the punch,
Wherein a region of the work to be pressed or cut by the punch is inserted or passed through the gap by the punch after completion of movement of the upper mold or the lower mold.
14. The method of claim 13,
The punch includes:
A protruding portion protruding at a predetermined height in the direction of the material is provided on the surface contacting the material,
The protruding portion
And is provided to come into contact with a region to be pressed or cut by the punch.
15. The method according to any one of claims 12 to 14,
The seating step comprises:
The forming region of the blank is correspondingly disposed on the blank holder mounted on the upper mold or the lower mold,
The forming step comprises:
And the blank holder is brought into contact with the forming region.
15. The method of claim 14,
The forming step comprises:
Wherein the protrusions are provided on the punches such that the protrusions have a height difference with respect to one surface of the workpiece, and a predetermined inclination is formed between the protrusions on the basis of one surface of the workpiece, Or cut.

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