KR20110108805A - Cross type molding in which drawbead is applied and the method for evaluating formability of steel sheet using therof - Google Patents

Abstract

The present invention relates to a cross-shaped mold to which the bead is applied and a method for evaluating the formability of the steel sheet using the same, based on the cross-shaped central groove portion formed in the upper direction from the center of the back, and the outline of the cross-shaped central groove portion An upper mold formed of a draw bead groove part spaced apart at a predetermined interval to the outside to be recessed with the same radius of curvature; And a cross-shaped through hole formed corresponding to the position and size of the cross-shaped central groove portion, and a draw bead portion formed to protrude so as to correspond to a position of the draw groove portion and have a radius of curvature smaller than or equal to the radius of curvature of the draw bead groove portion. It includes a holder.

Description

CROSS TYPE MOLDING IN WHICH DRAWBEAD IS APPLIED AND THE METHOD FOR EVALUATING FORMABILITY OF STEEL SHEET USING THEROF}

The present invention relates to a cross mold for drawing steel sheet moldability evaluation applied to the draw bead and a method for evaluating the formability of the steel sheet using the same, and more specifically to the cross mold used in the steel sheet moldability test, the same draw as the actual production mold By applying the beads, it is possible to test the formability of the steel sheet under conditions similar to the actual mass production mold conditions, and the cross mold to which the draw bead is applied to secure the reliability of the evaluation of the formability of the steel sheet, and the steel sheet formability evaluation method using the same Is about technology.

Drawing molding refers to a method of forming a shape by fixing a blank blank by a holder and then conveying a punch, which is one of typical press molding methods.

The mold used for such drawing molding is largely composed of a holder, a punch and a die.

When the initial blank is put into the mold, it is fixed by the die and the holder. Then the punch is transported to complete the final product.

At this time, when the blank blank is placed on the upper part of the holder, the upper die is lowered, and a draw bead of a predetermined shape protruding from the bottom of the upper die and the upper surface of the holder is pressed to alternate the upper and lower surfaces of the blank. Fix that position.

That is, the draw beads are used for the purpose of adjusting the flow rate of the blank at the time of forming by the punch.

On the other hand, the evaluation of the formability of the steel sheet can be improved only if the conditions under the same conditions as the mass production mold to increase the reliability, in the case of the actual mass production mold is most of the draw beads (approximately 90% or more).

Therefore, the method of more accurately evaluating the formability of the steel sheet through various control factors such as bead force and frictional force is not limited to the evaluation of the formability according to the flow rate of the steel sheet by thickness. As required.

According to the present invention, by applying the same draw beads as the actual mass production mold to the cross mold used for the steel sheet formability test, the moldability of the steel sheet can be tested in a state similar to the actual mass production mold condition to increase the reliability of the evaluation of the formability of the steel sheet. An object of the present invention is to provide a cross mold for drawing steel sheet formability evaluation to which draw beads are applied, and a method for evaluating the formability of steel sheet using the same.

In addition, the present invention analyzes the type of draw beads that are most applied to the actual production mold, and by applying the draw beads according to this type to the cross mold used for the evaluation of sheet formability, thereby improving the accuracy of the sheet formability evaluation It is an object of the present invention to provide a cross-shaped mold for evaluating sheet formability to which draw beads are applied and a method for evaluating formability of a steel sheet using the same.

According to the spirit of the present invention, a cross-shaped central recess formed in the upper direction from the center of the back and the draw bead recess formed in the same curvature radius spaced out at a predetermined interval from the outside based on the outline of the cross-shaped central recess Gypsum mold; And a cross-shaped through hole formed corresponding to the position and size of the cross-shaped center recess, and the draw-cord stone protruding to have a radius of curvature smaller than or equal to the radius of curvature of the draw-bead recess corresponding to the position of the draw-bead recess. It can provide a cross mold applied to the draw bead including a blank holder consisting of a negative.

At this time, the radius of curvature of the draw bead protrusion is preferably 4 ~ 6mm.

In addition, it is preferable that the radius of curvature of the portion curved from the outside to the die face of the draw bead protrusion is 2 to 3 mm.

In addition, it is preferable that the radius of curvature of the portion curved from the inside to the die face of the draw bead protrusion is 2 to 3 mm.

In addition, the radius of curvature of the draw bead recess is preferably 6mm.

On the other hand, according to another idea of the present invention, the cross-shaped center recess formed in the upper direction from the center of the back, and the draw bead formed in the same curvature radius spaced apart at a predetermined interval to the outside based on the outline of the cross-shaped center recess A cross-shaped through hole formed in correspondence to the position and size of the upper mold and the cross-shaped central recess of the recess, and a radius of curvature corresponding to the position of the draw bead recess and smaller than or equal to the curvature radius of the draw-bead recess. It is possible to provide a method for evaluating the formability of a steel sheet by using a cross mold to which a draw bead including a blank holder formed of a protrusion formed bead protrusion is applied.

At this time, the radius of curvature of the draw bead recess is 6mm, the radius of curvature of the draw bead protrusion is 6mm, the radius of curvature of the curved portion from the outside of the draw bead protrusion to the die face is 3mm, the inside of the draw bead protrusion The radius of curvature of the curved portion from to the die face may be 3 mm.

In addition, the radius of curvature of the draw bead recess is 6mm, the radius of curvature of the draw bead protrusion is 5mm, the radius of curvature of the curved portion from the outside of the draw bead protrusion to the die face is 3mm, the inside of the draw bead protrusion The radius of curvature of the curved portion from to the die face may be 3 mm.

In addition, the radius of curvature of the draw bead recess is 6mm, the radius of curvature of the draw bead protrusion is 4mm, the radius of curvature of the curved portion from the outside of the draw bead protrusion to the die face is 3mm, the inside of the draw bead protrusion The radius of curvature of the curved portion from to the die face may be 3 mm.

In addition, the radius of curvature of the draw bead recess is 6mm, the radius of curvature of the draw bead protrusion is 6mm, the radius of curvature of the curved portion from the outside of the draw bead protrusion to the die face is 2mm, the inside of the draw bead protrusion The radius of curvature of the curved portion from to the die face may be 2 mm.

According to the cross mold for drawing steel sheet formability evaluation applied to the present invention and the method for evaluating the formability of the steel sheet using the same, by providing a cross mold applied with the same draw bead as the actual mass production mold, There is an effect that can increase the reliability.

In addition, according to the cross mold for evaluating the formability of the steel sheet formability to which the draw bead of the present invention and the method for evaluating the formability of the steel sheet using the same, to analyze the type of draw bead most applied to the actual production mold, According to the draw bead is applied to the cross mold used for steel sheet formability evaluation, there is an effect that can increase the accuracy of the steel sheet formability evaluation.

In addition, according to the cross-shaped mold for evaluating the formability of the steel sheet to which the draw bead of the present invention and the method for evaluating the formability of the steel sheet using the same, it is necessary to verify the formability of the thin steel sheet that reacts sensitively to the formability of the material in advance. It is useful and very effective as a method for evaluating the formability for steel sheets for automobiles and the like which require thinner steel sheets in recent years.

1 is a view showing an upper mold of a cross mold for evaluation of formability of a steel sheet applied with a draw bead according to the present invention.
Figure 2 is a view showing a blank holder of the cross-shaped mold for evaluating sheet formability to which the draw beads are applied according to the present invention.
FIG. 3 is an enlarged view of a portion of the blank holder shown in FIG. 2; FIG.
4 is a cross-sectional view showing a cross-sectional view A to explain the draw bead protrusion in FIG.
Figure 5 is a comparative analysis of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, the molding analysis results shown to explain the case that the draw bead is not applied.
Figure 6 is a first embodiment of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, the molding analysis results shown to explain the case where the first type of the draw bead of Figure 4 is applied.
Figure 7 is a second embodiment of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, the molding analysis results shown to explain the case where the second type of the draw bead of Figure 4 is applied.
Figure 8 is a third embodiment of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, the molding analysis results shown to explain the case where the third type of the draw bead of Figure 4 is applied.
Figure 9 is a fourth embodiment of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, the molding analysis results shown to explain the case where the fourth type of the draw bead of Figure 4 is applied.

Hereinafter, a preferred embodiment of a cross mold for evaluating the steel sheet formability to which the draw beads according to the present invention and a steel sheet formability evaluation method using the same will be described.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, the present invention is not limited by the embodiments disclosed below, but may be embodied in various different forms, and the present embodiments merely make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. In addition, in the following description of the present invention, if it is determined that related related technologies and the like may obscure the gist of the present invention, detailed description thereof will be omitted.

1 is a view showing an upper mold of the cross-shaped mold for evaluation of the formability of the steel sheet to which the draw bead is applied according to the present invention, Figure 2 is a blank holder of the cross-shaped mold for evaluation of the formability of the steel sheet applied to the draw bead according to the present invention One drawing.

1 and 2 clearly illustrate only the main features in order to conceptually clearly understand the present invention, and as a result, various modifications of the drawings are expected, and the scope of the present invention is limited by the specific shapes shown in the drawings. It doesn't have to be.

The cross mold for drawing steel sheet formability evaluation according to the present invention includes an upper mold 100 shown in FIG. 1 and a blank holder 200 shown in FIG. 2. The upper mold 100 and the blank holder 200 is a shape that is engaged with each other, has a size and shape corresponding to each other.

First, the upper mold 100 will be described with reference to FIG. 1.

The upper mold 100 is provided with a cross-shaped central recess (110) and the draw bead recess (120).

The cross-shaped center recess 110 is formed in the upper direction from the center of the back surface of the upper mold 100.

As shown in FIG. 1, the cross-shaped central recess 110 looks like an upwardly protruding shape, but this is only because the upper mold 100 is shown in a mounting direction. Inside the rear surface, the cross-shaped central recess 110 has a recessed shape.

A draw bead recess 120 is formed on the outer side of the cruciform central recess 110.

Draw bead portion 120 is formed in the outward direction based on the outline of the cross-shaped center recess 110, the clearance between the outline of the cross-shaped center groove 110 and the draw bead groove portion 120 spaced apart from each other Area is formed.

Like the cross-shaped center recess 110, the draw bead recess 120 also looks like an upwardly projecting shape, which is due to the upper mold 100 in the mounting direction.

The draw bead recess 120 has a radius of curvature of 6 mm.

However, the size of the radius of curvature of the draw bead recess 120 is merely exemplary, and the present invention is not limited thereto. Therefore, the radius of curvature of the draw bead recess 120 through various embodiments as necessary may be differently performed within an appropriate range.

Next, the blank holder 200 will be described with reference to FIG. 2.

The blank holder 200 is provided with a cross-shaped through hole 210 and a draw bead protrusion 220.

The cross-shaped through-hole 210 refers to a hole through the cross-shaped hole in the center of the blank holder (200).

The cross-shaped through-hole 210 has a shape corresponding to each other with the cross-shaped center recess 110 of the upper mold 100 described in Figure 1, for this purpose corresponding to the position and size of the cross center recess 110 It has a through shape.

In addition, a draw bead part 220 is formed in the blank holder 200.

The draw-bead protrusion 220 is formed to be spaced apart from the cross-shaped through-hole 210 in the blank holder 200 to protrude.

The draw-bead protrusion 220 has a shape overlapping with the draw-bead recessed portion 120 of the upper mold 100 as shown in FIG.

To this end, it may be provided on the blank holder 200 corresponding to the position of the draw bead recess 120.

In addition, the draw bead protrusion 220 may have a radius of curvature less than or equal to the radius of curvature of the draw bead recess 120 of FIG. 1.

The radius of curvature of the draw bead protrusion 220 is preferably within the range of 4 ~ 6mm.

If the radius of curvature of the draw bead protrusion 220 is less than 4mm, it may be difficult to secure the effect of the draw bead protrusion 220 when the steel sheet formability evaluation through the cross-shaped mold.

On the other hand, when the radius of curvature of the draw bead protrusion 220 exceeds 6mm, the radius of curvature becomes larger than that of the draw bead recess 120 of FIG. 1, and thus may be out of the object of the present invention.

FIG. 3 is an enlarged view of a part of the blank holder shown in FIG. 2, and FIG. 4 is a cross-sectional view illustrating a cross-section A of FIG. 3 to explain the draw bead protrusion.

First, referring to FIG. 3 by expanding one corner of the cross-shaped through hole in the blank holder 200, the shape of the draw bead protrusion 220 according to the present invention can be confirmed in more detail.

3 is a cross-sectional view showing a cross-section A in FIG. Referring to FIG. 4, it can be seen that there are three radiuses of curvature based on the draw bead protrusion 220 on the cross-section A of FIG.

First, the radius of curvature represented by "bead R" in Figure 4 means the radius of curvature of the draw bead protrusion 220, the radius of curvature represented by "outer R" is a die face from the outside of the draw bead 200 It means the radius of curvature of the curved portion up to 230).

In addition, the radius of curvature expressed as "inner R" means the radius of curvature of the curved portion from the inside of the draw-bead protrusion 220 to the die face 230.

Here, by specifying three curvature radii represented by the bead R, the outer R, and the inner R, the shape of the draw bead protrusion 220 may be specified.

Example

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

1. Cruciform Design for Evaluating Sheet Formability with Draw Beads

The shape of the draw-bead protrusion was designed under the four types (Type 1 to 4) conditions described in the following [Table 1], and the moldability for the automotive steel sheet was tested by dividing it into Examples 1 to 4.

Here, in Examples 1 to 4, the radius of curvature of the draw bead recess is 6 mm in common.

And the radius of curvature represented by "bead R" means the radius of curvature of the draw bead protrusion, the radius of curvature represented by "outer R" means the radius of curvature of the curved portion from the outside to the die face of the draw bead protrusion, The radius of curvature expressed by "inner R" means the radius of curvature of the curved portion from the inner side to the die face of the draw-bead protrusion.

TABLE 1

2. Evaluation of Formability of Steel Sheet

First, with reference to FIGS. 6 to 9, prior to examining the first to fourth embodiments, FIG. 5 without a drawbead will be described to compare the effects of the present invention.

Comparative example

5 is a comparative example of the molding analysis for verifying the bead influence of the steel sheet for automobiles using the present invention, it is a molding analysis results shown to explain the case that the draw bead is not applied.

Referring to FIG. 5, it can be seen that an area in which a safe area is small and severe wrinkles are generated in all areas of the automotive steel sheet.

Example 1

In Example 1, the beads R were 6 mm, the outer R was 3 mm, and the inner R was 3 mm.

6 is a molding analysis result verifying the bead effect of the steel sheet for automobiles by applying the first embodiment.

Referring to FIG. 6, it can be seen that the first embodiment, unlike the comparative example, secured much more safe area in the entire area of the automotive steel sheet.

However, it can be seen that the amount of thinning in the upper and lower regions, including the central sidewall region of the automotive steel sheet, is somewhat insufficient.

Example 2

In the present Example 2, the bead R was 5 mm, the outer R was 3 mm, and the inner R was 3 mm.

 7 is a molding analysis result verifying the bead influence of the steel sheet for automobiles by applying the second embodiment.

Referring to FIG. 7, it can be seen that the second embodiment, unlike the comparative example, secured much more safe area in the entire area of the automotive steel sheet.

However, similarly to the first embodiment described above, in the second embodiment, it can be seen that the amount of thinning in the upper and lower regions, including the central sidewall region of the automotive steel sheet, is somewhat insufficient.

Example 3

In the third embodiment, the beads R were 4 mm, the outer R was 3 mm, and the inner R was 3 mm.

8 is a molding analysis result verifying the bead impact of the steel sheet for automobiles by applying the third embodiment.

Referring to FIG. 8, it can be seen that the third embodiment, unlike the comparative example, secured much more safe regions in all regions of the automotive steel sheet.

However, similarly to Examples 1 and 2 described above, in Example 2, it can be seen that the amount of thinning in the upper and lower regions, including the central sidewall region of the automotive steel sheet, is somewhat insufficient.

Example 4

In Example 4, the beads R were 6 mm, the outer R was 2 mm, and the inner R was 2 mm.

9 is a molding analysis result verifying the bead impact of the steel sheet for automobiles by applying the fourth embodiment.

Referring to FIG. 9, in contrast to the comparative example, the fourth embodiment shows that much more safe regions are secured in all regions of the automotive steel sheet.

In addition, unlike Embodiments 1 to 3 described above, in the fourth embodiment, it can be seen that the amount of thinning is sufficient in the upper and lower regions as well as the central sidewall region of the automotive steel sheet.

Therefore, in order to evaluate the formability of the automotive steel sheet to be subjected to this test, by using a cross mold to which a bead R having a 6 mm bead R, a 2 mm outer R, and a 2 mm inner R is applied, the reliability and accuracy of the evaluation of the formability are improved. It could be confirmed that.

The cross mold for evaluating the steel sheet formability to which the draw beads according to the present invention and the steel sheet formability evaluation method using the same have been described above.

It is to be understood that the above-described embodiments are illustrative in all aspects and should not be construed as limiting, the scope of the invention being indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

100: upper mold 200: blank holder

Claims (10)

An upper mold formed of a cross-shaped central recess formed in the upper direction from the rear center and a draw bead recess formed in the same curvature radius spaced outwardly at a predetermined interval based on an outline of the cross-shaped central recess; And
A cross-shaped through hole formed corresponding to the position and size of the cross-shaped center recess, and a draw-bead protrusion protruding to have a radius of curvature smaller than or equal to the radius of curvature of the draw-bead recess, corresponding to the position of the draw-bead recess. Blank mold for forming a steel sheet applied to the draw bead comprising a blank holder made.
The method of claim 1,
The radius of curvature of the draw bead protrusion is a cross-shaped mold for evaluation of the formability of the steel sheet applied to the draw bead, characterized in that 4 ~ 6mm.
The method of claim 1,
The curvature radius of the curved portion from the outer side of the draw bead protrusion to the die face is 2 to 3 mm, the cross-shaped mold for evaluation of the formability of the steel sheet applied to the draw bead.
The method of claim 1,
The curvature radius of the curved portion from the inner side of the draw bead protrusion to the die face is 2 to 3 mm, the cross-shaped mold for evaluation of the formability of the steel sheet applied to the draw bead.
The method of claim 1,
The curvature radius of the draw bead recess portion is 6mm crosshair for evaluating the formability of the steel sheet applied to the draw bead.
The cross-shaped central recessed portion formed in the upper direction from the center of the back, and the upper mold and the cross-shaped central recessed portion consisting of a draw bead formed in the same radius of curvature spaced out at regular intervals to the outside based on the outline of the cross-shaped central recess A blank holder formed of a cross-shaped through hole formed in correspondence with a position and size of the draw bead portion protruding to correspond to a position of the draw bead recess and to have a curvature radius smaller than or equal to the curvature radius of the draw bead recess; Method for evaluating the formability of the steel sheet using a cross-shaped mold is applied to the containing bead.
The method according to claim 6,
The radius of curvature of the draw bead recess is 6 mm, the radius of curvature of the draw bead protrusion is 6 mm, the radius of curvature of the bent portion from the outside of the draw bead protrusion to the die face is 3 mm, and the die from the inside of the draw bead protrusion is die. The radius of curvature of the curved portion up to the face is a method for evaluating the formability of the steel sheet using a cross-shaped cross-shaped mold applied to the draw bead.
The method according to claim 6,
The radius of curvature of the draw bead recess is 6 mm, the radius of curvature of the draw bead protrusion is 5 mm, the radius of curvature of the bent portion from the outside of the draw bead protrusion to the die face is 3 mm, and the die from the inside of the draw bead protrusion is die. The radius of curvature of the curved portion up to the face is a method for evaluating the formability of the steel sheet using a cross-shaped cross-shaped mold applied to the draw bead.
The method according to claim 6,
The radius of curvature of the draw bead recess is 6 mm, the radius of curvature of the draw bead protrusion is 4 mm, the radius of curvature of the bent portion from the outside of the draw bead protrusion to the die face is 3 mm, and the die from the inside of the draw bead protrusion is die. The radius of curvature of the curved portion up to the face is a method for evaluating the formability of the steel sheet using a cross-shaped cross-shaped mold applied to the draw bead.
The method according to claim 6,
The radius of curvature of the draw bead recess is 6 mm, the radius of curvature of the draw bead protrusion is 6 mm, the radius of curvature of the bent portion from the outside of the draw bead protrusion to the die face is 2 mm, and the die from the inside of the draw bead protrusion is die. The radius of curvature of the curved portion up to the face is a method for evaluating the formability of the steel sheet using a cross-shaped cross-shaped mold applied to the draw bead.

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