JPH05200414A - Method for manufacturing dull roll for rolling - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a dull roll for rolling in which the high image clarity after coating is remarkably improved by subjecting the surface of a steel sheet to Cr plating. [Structure] As the surface of a work roll for rolling is scanned, high-density energy is irradiated to form innumerable minute irregularities on the roll surface, and the roll thus processed is dipped in a chromic acid solution. In the method for processing the rolling roll for chrome plating, before the chrome plating on the roll surface, after the softening portion of the fine convex surface layer formed by irradiation with high-density energy is removed in advance, A method for producing a dull roll for rolling, which comprises immersing in a chromium solution and subjecting it to chromium plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling roll having a roll surface provided with a predetermined roughness pattern, and a method for producing the rolling roll. The present invention relates to a rolling roll for producing a steel sheet (cold rolled steel sheet, surface-treated steel sheet, aluminum alloy sheet, hot rolled steel sheet) having significantly improved press formability, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a cold-rolled steel sheet for working has a dull finish on its surface in order to facilitate press working. That is, the lubricating oil for processing is stored in the irregularities formed on the surface of the steel sheet during press working, which reduces wear on the die and the steel sheet and prevents seizure. In addition, research on press formability has been conducted from both the side of the steel plate as the material and the forming technology, but the required characteristics for steel plates are becoming more sophisticated and diversified with the increasing precision and complexity of products. .. Therefore, as a current situation, in the temper rolling for finally adjusting the steel plate roughness, shot blasting, electric discharge,
Alternatively, the roughness is transferred to the surface of the steel sheet by using a work roll that has been dull processed with a laser or the like. Further, the evaluation criteria for the actual press formability are not sufficient only by the mechanical properties (r value, El value, etc.) of the steel sheet that have been used in the past, and the steel plate surface roughness lubricating oil etc. has a great influence on the press formability. Exert.

Exterior steel sheets for automobile bodies, home appliances and the like are painted to give them an aesthetic appearance. At this time, the appearance is not impaired by the diffuse reflection of the coated surface, which is excellent in sharpness. Required. Therefore, for example, by improving the surface roughness profile of the steel sheet to reduce the unevenness of the painted surface after painting and to increase the proportion of the horizontal portion, the specular reflectance of light is improved and the distortion of the image is reduced. Japanese Patent Application Laid-Open No. 62-168602 discloses a steel sheet that can improve the sharpness after painting as compared with the conventional steel sheet. However, in this case, the laser processing roll for rolling is
The initial wear of the convex portions on the surface is large, and the wear resistance is unavoidably reduced. As a method for reducing the decrease in roughness at the initial stage of rolling, chrome plating is applied after laser processing to improve wear resistance. JP-A-62-15859
No. 1 publication is known.

[0004]

These known patents are
It is excellent in that it improves the image clarity after coating, and in Japanese Patent Laid-Open No. 62-168602, a trapezoidal shape in which the microscopic morphology constituting the surface roughness has a flat top surface. It is intended to improve the sharpness of the coating film after coating by forming the mountain portion and the groove-shaped valley portion formed so as to surround all or a part of the surrounding area.
However, the very surface layer of the convex portion of the roll surface roughened by laser processing has a residual austenite phase that is softer than the base material, and there is a problem that the roll life is shortened by abrasion in the initial rolling. .. In JP-A-62-158591 for the purpose of improving the wear resistance of the roll, the wear resistance is improved by plating the surface of the retained austenite phase in the very surface layer of the roughened surface of the roll surface with chromium. Even if it is excellent in that it imparts the property and reduces the wear during rolling, the surface hardness of the residual austenite phase of the chrome plating base, that is, the very surface layer of the convex portion of the roll surface is low. In this case, there is a disadvantage that the roughened surface convex portion of the roll is depressed during rolling, which leads to peeling of the chrome plating, and the abrasion resistance of the laser processing roll cannot be improved.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the problems of the prior art in an advantageous manner. The gist of the present invention is to scan the surface of a work roll for rolling. After irradiating the roll surface with high-density energy, a large number of minute irregularities are formed, and after removing the softened portions of the minute convex surface layers of the rolling roll surface processed in this way in advance, chrome plating is performed. In the rolling roll, the chrome plating treatment on the roll surface is performed by degreasing, washing, electrolytic etching, etc.
Electroplating is performed, but at this time, the softening part of the fine convex surface layer on the surface of the rolling roll is ground and removed by the roll grinding device in advance, and then it is immersed in the chromic acid solution to perform the chrome plating treatment. It is a characteristic method for producing a dull roll for rolling.

The present invention will be described below with reference to the drawings. FIG. 1 schematically shows the cross-sectional shape of the roll surface according to the present invention, and FIG. 1- (A) shows the cross-sectional shape of the roll according to the conventional method. The surface of the roll 1 is irradiated with a laser, and the chrome plating 3 is applied from above the softened portion 2 on the surface of the minute projections formed on the surface of the roll, which aims to reduce the wear of the projections at the initial stage of rolling. I am trying. However, since the softened portion 2 sandwiched between the chrome plating 3 on the roll surface convex portion and the roll base 1 has a softened retained austenite phase and is lower in hardness than the roll base 1, when rolled as it is, If the projections on the roughened roll surface are depressed, the chromium plating 3 may be peeled off, and the abrasion resistance of the laser processing roll cannot be improved. FIG. 1- (B) schematically shows a roll cross-sectional shape according to the present invention which solves the conventional problem.
Innumerable minute irregularities are formed on the surface of the roll 1, the softening portion 2 on the surface layer of the protrusion is removed in advance, and then the chrome plating 3
By the treatment, the convex surface layer is formed in a state where there is no retained austenite phase softened as compared with the roll base 1. In addition to the mechanical removal method by the roll surface polishing, the removal method by electrolytic etching and the forced removal method by idling of the roll before rolling can be used as the prior removal method of the softened portion 2 on the surface layer of the roll convex portion. Yes,
In any method, the softened portion 2 on the surface layer of the roll convex portion can be removed similarly.

FIG. 2 shows a method for removing the softened portion 2 on the surface layer of the convex portion of the roll according to the present invention, before forming a myriad of minute irregularities on the surface of the roll 1 and chrome plating 3 on the surface layer of the convex portion. 2 shows a roll grinding device for removing the softening portion 2 of the roll convex portion in advance. The roll is placed on the grinding device, and the roll is rotated by the roll rotating device 4, and at the same time, the grindstone 6 is rotated by the grindstone rotating motor 5 to give a cut to the roll. At this time, the grindstone carriage 7 is shifted in the roll axial direction while maintaining the load current of the grindstone rotating motor 5 in the range of no load + 1 to 20 A, so that the softening portion 2 of the convex portion on the surface of the roll 1 is mechanically moved. To remove. In this mechanical method for removing the softened portion of the convex portion, the load current of the grindstone rotating motor 5 is set to the no-load current value +1 to 20.
It is important to manage within the range of A. If the load current of the grindstone rotating motor 5 is 1 A or less, it is not possible to sufficiently remove the convex softening portion of the roll surface, and when the chrome plating 3 is applied from above, the roughened roll surface Of the chrome plating, and eventually the chrome plating is peeled off, and the wear resistance of the laser processing roll cannot be improved. on the other hand,
When the load current of the grindstone rotating motor 5 becomes 20 A or more, not only the convex softening portion but also the entire convex portion is removed. Therefore, as a roughening roll, an appropriate roughness is transferred to the steel plate surface by rolling. I can't.

[0008]

Example A surface of a work roll for temper rolling of 5% Cr forged steel having a diameter of 610 mm was irradiated with a laser beam by a YAG laser processing machine, and laser dull processing was applied to a predetermined roughness pattern. The laser irradiation conditions are as follows. Laser average output: 60 W Laser processing frequency: 8 kHz Roll processing pattern: Hole diameter 170 μm Hole pitch 340 μm (roll circumferential direction, longitudinal direction) Then, the processed roll is placed on a grinding machine and the roll and grindstone are rotated. A cut was made so that the load current of the grindstone rotation motor would be the no-load current value +5 A, and while maintaining this current value, it was shifted in the roll axis direction, and the convex softening portion on the roll surface was ground. .. afterwards,
Chromium plating with a thickness of 5 μm was performed using a chromic acid solution. Using this roll, low carbon A with a plate thickness of 0.8 mm
The annealed coil of 1-killed steel was temper-rolled at a rolling reduction of 1.0%, and the wear resistance of the convex portion of the roll surface was investigated. FIG. 3 shows the wear behavior of the convex portion on the roll surface after rolling 50 km in temper rolling. In the conventional method, about 10μ before rolling
The height of the convex portion of the roll surface of m is 7 μm in the initial rolling wear, and the roll life limit is reached when the rolling length is 10 km.
(Assuming that the life limit of the height of the convex portion of the roll surface is 2 μm) On the other hand, in the present invention, the initial abrasion of the convex portion of the roll surface does not show the initial rolling abrasion as in the conventional method,
The roll life was about 10 times longer, and in the examples of the present invention, the initial wear of rolling was prevented by the chrome plating treatment after removing the softened portion of the roll surface layer, and the wear resistance was dramatically improved.

[0009]

INDUSTRIAL APPLICABILITY According to the method of the present invention, it is possible to form innumerable minute irregularities on the surface of the roll by laser dull processing, and by applying chrome plating to this, wear resistance of the convex portion of the roll is improved. The chrome plating with high wear resistance can be formed from the state where the softened portion of the convex surface layer is removed before this chrome plating treatment and the retained austenite phase softened more than the roll base does not exist, and the chrome plating during rolling can be formed. It is possible to significantly reduce the initial wear during rolling without causing chrome plating peeling off, and to dramatically improve the roll life.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional shape of a roll surface according to the present invention,

FIG. 2 is a diagram showing a roll grinding apparatus for removing a softened portion of a convex portion of a roll surface according to the present invention,

FIG. 3 is a diagram showing roll life of the roll of the present invention.

[Explanation of symbols]

 1 roll 2 softening part 3 chrome plating 4 roll rotation device 5 grindstone rotation motor 6 grindstone 7 grindstone carriage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C25D 7/04

Claims (1)

[Claims] 1. The surface of a work roll for rolling is irradiated with high-density energy so as to form innumerable minute irregularities on the roll surface, and the minute protrusions on the surface of the rolling roll processed in this manner. After removing the softened part of the surface layer in advance, in a rolling roll for chrome plating, the chrome plating treatment on the roll surface is performed by degreasing, washing, electrolytic etching, etc. However, at this time, the softening part of the fine convex surface layer of the rolling roll surface is ground and removed by a roll grinding device in advance, and then immersed in a chromic acid solution for chrome plating. Manufacturing method of dull roll for rolling.