KR101180616B1 - Apparatus for work hardening of steel sheet - Google Patents

Abstract

Disclosed is a steel sheet work hardening apparatus capable of increasing the strength of an IF steel sheet or the like using work hardening.
Steel sheet work hardening apparatus according to the present invention is a steel sheet supply unit for continuously supplying a steel sheet; A work hardening processing unit configured to have a bending path including an inlet bending path, at least one internal bending path and an exit bending path, to harden the supplied steel sheet; And a winding-up part for winding the work hardened steel sheet, wherein the bending path is formed such that the steel sheet is bent at an obtuse angle.

Description

Steel Plate Work Hardening Equipment {APPARATUS FOR WORK HARDENING OF STEEL SHEET}

The present invention relates to a work hardening apparatus of a steel sheet, and more particularly, by using work hardening by shear strain, it is possible to improve the strength of a steel sheet having low strength to elongation as compared to an IF (Interstitial Free) steel sheet. A steel sheet work hardening apparatus.

The steel sheet may be classified into various types such as IF steel sheet, mild steel sheet, IF-HSS steel sheet, baking hardened steel sheet, and TRIP steel sheet according to alloy composition, manufacturing process, final microstructure, and the like.

Homogeneous steel sheets generally have similar mechanical properties such as tensile strength and elongation.

1 is a graph schematically showing the mechanical properties according to the type of steel sheet.

Referring to FIG. 1, in the case of the IF steel sheet, the elongation is high while relatively low in strength.

In the case of the IF steel sheet, the carbon content is about 0.15% by weight, and the carbon content ratio is relatively lower than that of other steel grades. Accordingly, the moldability and aging characteristics are excellent.

IF steel sheets, on the other hand, have relatively low strength compared to other steel grades due to their low carbon content. Accordingly, the application range of IF steel sheet is limited in the field where high strength is required.

Accordingly, in order to expand the application range of IF steel sheet having excellent elongation while having relatively low strength, etc., a technique capable of increasing the strength of the IF steel sheet is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steel sheet work hardening apparatus that can be hardened by shear strain by providing a bending path by applying a V-shaped groove pressing technique or the like.

Steel sheet work hardening apparatus according to an embodiment of the present invention for achieving the above object is a steel sheet supply unit for continuously supplying a steel sheet; A work hardening processing unit configured to have a bending path including an inlet bending path, at least one internal bending path and an exit bending path, to harden the supplied steel sheet; And a winding-up part for winding the work hardened steel sheet, wherein the bending path is formed such that the steel sheet is bent at an obtuse angle.

In the steel sheet work hardening apparatus according to the present invention, the shear strain may be made while the steel sheet passes through the bending path. Therefore, the work hardening effect due to the shear deformation, that is, the grains of the steel sheet can be refined, thereby increasing the strength of the steel sheet.

Therefore, the steel sheet work hardening apparatus according to the present invention has the advantage of improving the strength of a steel sheet having excellent ductility but relatively weak strength, such as an IF steel sheet, and expanding an application range of an IF steel sheet.

1 is a graph schematically showing the mechanical properties according to the type of steel sheet.
Figure 2 schematically shows a steel plate work hardening apparatus having three bending paths according to an embodiment of the present invention.
3 shows an example of a work hardening processing unit having four bending paths.

Hereinafter, a steel sheet work hardening apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation.

In addition, the terms described below are terms defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator.

Therefore, definitions of these terms should be made based on the contents throughout the specification.

Figure 2 schematically shows a steel plate work hardening apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the illustrated steel plate work hardening device includes a steel plate supply unit 210, a work hardening processing unit 220, and a winding unit 230.

The steel sheet supply unit 210 continuously supplies the steel sheet to be subjected to work hardening. The steel sheet may be supplied in a wound state as in the example shown in FIG. 2, and may be continuously supplied in connection with a rolling process.

In the present invention, the steel sheet is aimed at high strength through work hardening, and an IF (Interstitial Free) steel sheet having excellent ductility and insufficient strength may be applied.

The work hardening treatment unit 220 hardens the steel sheet supplied with an inlet bending path and at least three bending paths. When the steel sheet passes through the bending paths 225a, 225b, and 225c as in the example shown in FIG. 2, shear strain occurs in the steel sheet as the steel sheet is bent, and grains are refined as the strain accumulates. Can be.

In the case of non-ferrous copper (Cu) and titanium (Ti), Valiev's Paradox, a phenomenon in which strength and ductility increase due to grain refinement, is known. In addition, the Hall-Petch equation (Hall-Petch equation) is also known to increase the strength due to the grain refinement, even in the case of steel sheets lacking strength, such as IF steel sheet can be pursued to increase the strength through the refinement of the grain.

As shown in FIG. 2, the strength of the steel sheet using the bending of the steel sheet in the bending paths 225a, 225b, and 225c may be regarded as work hardening because it is a kind of processing.

Work hardening is mainly applied to a bulk material as an intermittent process, but in the present invention, it can be carried out in connection with a rolling process and the like, and can also be applied to a plate by using steel sheet bending.

In the present invention, each of the bending paths 225a, 225b, and 225c included in the work hardening treatment unit 220 should be formed so that the steel sheet is bent at an obtuse angle greater than 90 °. The reason is that when the steel sheet is bent at an acute angle of less than 90 degrees or less than 90 degrees, plate breakage is more likely to occur due to excessive bending.

In addition, each of the bending paths 225a, 225b, and 225c is preferably formed such that the angle at which the steel sheet is bent is 100 ° to 155 °. When the bending angle of the steel sheet is less than 100 ° may indicate the problem of excessive bending as described above, when the bending angle of the steel sheet exceeds 155 ° bending degree is low may be insufficient work hardening effect.

In addition, when the bending angle of the steel sheet is limited to 100 ° ~ 155 ° as described above, when the steel sheet is subjected to three or more bendings, the work hardening effect, that is, the grain refinement of the steel sheet is large, is shown once or twice. If only bending was present, the grain refinement of the steel sheet was insufficient.

As shown in FIG. 2 in the work hardening processing unit 220, when the bending path is three or more, the bending path includes an inlet bending path 225a, at least one inner bending path 225b and at least one inner bending path and an outlet bending. It may include a path. For example, assuming that the steel sheet is transported horizontally from right to left, the direction of the steel sheet conveyed by the first bend in the inlet bending path is changed from horizontal to left to left and upwards, and in the exit bending path to the last bend. As a result, the conveying direction of the steel sheet is changed from the lower left direction to the upper direction horizontally.

In addition, referring to FIG. 2, the work hardening treatment unit 220 may include a lower mold 221 and an upper mold 222.

The lower mold 221 has a V-shaped groove, and the upper mold 222 has a shape corresponding to the V-shaped groove of the lower mold.

The upper mold 222 is controlled to raise and lower through the upper mold raising and lowering control unit 223 to provide bending paths 225a, 225b, and 225c at the inlet, the inside, and the outlet of the V-shaped groove to pass the steel sheet. To help.

At this time, the interval between the lower mold 221 and the upper mold 222 is not particularly limited. The larger the distance between the lower mold 221 and the upper mold 222, the easier it is to pass through the steel sheet. However, if the interval is too large, the compressive force applied to the steel sheet becomes small, which may easily cause plate breakage. Thus, the spacing between the lower mold 221 and the upper mold 222 is preferably similar to the steel sheet thickness.

On the other hand, the V-shaped groove of the lower mold 221 should be formed so that the steel sheet can be bent at an obtuse angle. In the example shown in FIG. 2, when the bending angle θ2 inside the V-groove is 100 ° to 130 °, the bending angle θ1 at the inlet of the V-shaped groove and the bending angle θ3 at the exit of the V-shaped groove are 140. ° to 155 °.

Of course, in the case of the example shown in FIG. 2, one symmetrical V-groove is formed, and since the conveying direction of the steel sheet is also in the horizontal direction as a whole, the range of the bending angle of the steel sheet as described above is limited. However, the shape, the number of V grooves, and the direction of transport of the steel sheet may vary. Accordingly, the angle at which the steel sheet is bent at the inlet, the inside and the outlet of the V-shaped groove as a whole may be adjusted to 100 ° to 155 °.

The inlet, the inside and the outlet of the V-shaped groove in the lower mold 221 may be formed in an angular shape. In addition, at least one of the inlet, the inside, and the outlet of the V-shaped groove in the lower mold 221 may be formed in a curved shape.

Since the amount of shear deformation may be greater in the angular shape than in the curved shape, when the curvature of the angular shape is zero, the curvature is preferably closer to zero. However, this may cause a wear problem of the steel sheet or the mold.

Therefore, in view of these points, it is preferable that the inlet, the inside and the outlet of the V-shaped grooves are formed into curved surfaces having as low curvature as possible, approximately 1/2 or less of the steel sheet thickness.

In addition, the work hardening treatment unit 220 may further include a cooling channel 224 for controlling heat generated during work hardening of the steel sheet.

The cooling channel 224 may be provided in any one of the lower mold 221 and the upper mold 222, and as shown in FIG. 2, the cooling channel 224 may be provided in both the upper mold 222 and the lower mold 221. Can be.

In consideration of minimizing temperature variation of both sides of the steel sheet and cooling efficiency, it is preferable that cooling channels 224 are provided in both the lower mold 221 and the upper mold 222, and at regular intervals from the surfaces of the respective molds 221 and 222. More preferably, cooling channels are provided.

In addition, the steel sheet work hardening apparatus according to the present invention, as shown in Figure 2, includes a winding unit 230 for winding the work-hardened steel sheet.

In the present invention, the winding unit 230 may include a driving means such as a motor to provide a conveying force to which the steel sheet may be conveyed. The feed force may be provided in the steel sheet supply unit 230, but when the feed force is provided at the front end of the work hardening treatment unit, the stress that the mold receives while the steel sheet receives the compressive force may increase. Therefore, the feed force is provided at the rear end of the work hardening treatment unit, so that the stress received by the mold can be relatively reduced while the steel sheet receives the tensile force.

In addition, the steel sheet work hardening apparatus according to the present invention is disposed between the work hardening treatment unit 220 and the winding unit 230, the flattening unit is formed in the form of a pair of rolls and the like to flatten the surface of the work hardened steel sheet 240 may further include.

In the above description, three bending paths are defined by a lower mold having a V-shaped groove and an upper mold having a shape corresponding thereto, but the number of bending paths included in the work hardening treatment unit in the steel plate work hardening apparatus according to the present invention. And forms are not limited thereto.

3 shows another example of the work hardening treatment unit.

In the example shown in FIG. 3, four bent paths 510a, 510b, 510c, and 510d are provided according to the shapes of the lower mold 221 and the upper mold 222. Also in the case of the example shown in Figure 3 it is possible to make the feed direction of the steel sheet at the inlet and outlet of the work hardening treatment unit can be easily linked to other processes such as a rolling process.

As described above, the steel sheet work hardening apparatus according to the present invention can achieve high strength by miniaturizing the grains of the steel sheet by work hardening due to shear deformation. Therefore, the steel sheet work hardening apparatus according to the present invention can expand the application range of the IF (Interstitial Free) steel sheet, which is excellent in elongation but relatively weak compared to other steel grades.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand.

Therefore, the true technical protection scope of the present invention will be defined by the claims below.

210: steel sheet supply unit
220: work hardening processing unit
221: lower mold
222: upper mold
223: upper and lower die lowering control
224: cooling channel

Claims (11)

A steel sheet supply unit for continuously supplying steel sheets;
A work hardening processing unit configured to have a bending path including an inlet bending path, at least one internal bending path and an exit bending path, to harden the supplied steel sheet; And
Includes; winding unit for winding the work-hardened steel sheet,
The bending path is characterized in that the steel sheet is formed to be bent at an obtuse angle (obtuse angle),
The work hardening processing unit includes a lower mold having at least one V-shaped groove formed therein, and an upper mold having a shape corresponding to the V-shaped groove of the lower mold,
The upper mold is raised and lowered to provide a bending path at the inlet, the inside and the outlet of the V-shaped groove.
The method of claim 1,
The steel sheet is a steel sheet processing hardening apparatus, characterized in that the IF (Interstitial Free) steel sheet.
The method of claim 1,
The bending path is a steel plate processing hardening apparatus, characterized in that formed so that the angle of the steel sheet is bent to 100 ° ~ 155 °.
delete The method of claim 1,
The work hardening treatment unit further comprises a cooling channel for controlling heat generated during work hardening of the steel sheet.
The method of claim 5,
And said cooling channel is provided on both said upper mold and said lower mold.
The method of claim 1,
Steel sheet bending at the inlet, the inside and the exit of the V-shaped groove is a steel sheet processing hardening apparatus, characterized in that 100 ° ~ 155 °.
The method of claim 1,
The inlet, the inside and the outlet of the V-shaped groove is a steel plate processing hardening apparatus, characterized in that formed in an angular form.
The method of claim 1,
At least one of the inlet, the inside and the outlet of the V-shaped groove is a steel plate processing hardening apparatus, characterized in that consisting of a curved shape.
The method of claim 1,
The winding unit provides a steel sheet processing hardening apparatus, characterized in that for providing a conveying force for transferring the steel sheet.
The method of claim 1,
And a flattening part disposed between the work hardening treatment part and the winding part to flatten the surface of the work hardened steel sheet.

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