JPS62158587A - Laser beam dull working method for cold rolling roll - Google Patents

Abstract

PURPOSE:To obtain the roll having excellent wear resistance by giving a favorable unevenness to a cold rolled roll, by performing a laser dull working with spraying the sintered hard alloy powder of the specified grain diameter with a gas on the roll surface. CONSTITUTION:A roll 1 is fitted to the rotary supporting device of a roll and rotated at the prescribed speed. On the other hand, the laser beam oscillated from a laser oscillator is adjusted in the prescribed beam by an optical deice and irradiated on the roll 1 surface. The sintered hard alloy powder <=3mum grain diameter is blown on the roll 1 surface together with a gas toward the irradiating part of a laser head 4. The laser irradiating head 4 moves in the roll axial direction by the turn of the driving screw 5 synchronized with the roll rotation. The laser beam is pulsated in the prescribed frequencies and by setting the frequency and output of the pulse and the number of roll rotation and the moving speed of the laser beam irradiating head 4 the pattern and depth of the surface roughness are controlled.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for laser dulling of cold rolling rolls, and more particularly to a cold rolling method for cold rolling rolls, which roughens the surface of a metal material into a desired pattern and depth of irregularities by laser dulling. The present invention relates to a laser dulling method characterized by imparting wear resistance of fp to an interroll roll or a temper roll.

[Conventional technology]

Surface quality is an important quality of rolled steel sheets.

Surface quality includes beauty, paint and enamel density, press workability, corrosion resistance, and gloss.

The geometrical shape of the plate, i.e. the surface J'11, depends on those properties.
is important; has an impact.

The most common method is to prepare the metal surface with the desired surface roughness depending on the application (14). The steel plate is rolled with this roll at a predetermined pressure, and the roughness of the roll surface is transferred to the plate surface.

As a technology to replace the conventionally widely used methods of roughening the roll surface, such as John de blasting and pre-discharge ball υ,
Recently, a processing method using a laser beam (hereinafter referred to as laser dull processing) has been proposed. For example, JP-A-56-16
0892, JP 58-25557, JP 54-61
043, Japanese Unexamined Patent Publication No. 55-94790, etc. but,
All of these describe in detail how to irradiate the laser pulse, but do not mention the characteristics of the irradiated roll.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a laser dull processing method that eliminates such problems.

However, laser dulling can form a fine uneven pattern with an orderly pitch on the roll surface.

The irradiated part of the roll melts instantaneously, and the molten metal scatters and builds up around it, forming the four parts of the hole and the convex part, giving it roughness. There is a problem that the convex portions of the fine irregularities created by the metal structure have a metal structure with poor wear resistance, resulting in a short life span.

[Means for solving problems]

That is, the present invention is characterized in that when roughening the roll surface by performing laser dulling on the surface of a cold rolling roll, the laser dulling is performed while spraying cemented carbide powder with a particle size of 3 ILm or less onto the roll surface. This is a method for laser dulling a rolling roll.

mra powder, WC, NbC, TiC1VC, C
rC is preferred.

It is preferable to perform laser dulling while vacuum suctioning such surplus scattered cemented carbide powder.Also, it is preferable to irradiate the roll with a laser beam from the horizontal direction and spray the cemented carbide powder from above to remove the surplus superhard powder. In terms of work efficiency, it is preferable to carry out laser dull processing while sucking and recovering the hard powder from below.

[Effect]

When roughening a cold rolling roll by laser dulling, if the laser dulling process is performed while spraying cemented carbide powder, the surface of the roll will be roughened by irradiating a laser beam with a laser device. melts into the molten layer on the roll surface and forms a hardened layer. Examples of cemented carbide powder include WClNbC, TiC, VC, Crct, etc.
Uses metal carbide. These fine powders have a particle size of 3 gm or less in order to dissolve into the molten pool of laser dull processing. As a carrier gas for spraying, an inert assist gas such as N2. Ar and He7 are used.

Hereinafter, the method of the present invention and its operation will be explained in more detail with reference to the drawings.

FIG. 11M and FIG. 2 show an overall view of a surface roughening apparatus that can be suitably used for carrying out the present invention.

The roll l is attached to a roll rotation support device 2 having a configuration similar to that of a machine tool such as a lathe or a grinder, and is rotated at a predetermined speed.

On the other hand, the laser beam L output from the laser oscillator 3 passes through a plurality of mirrors and is approximately applied to the roll surface! ■It is irradiated directly. The laser beam is A-aligned into a predetermined beam by an optical device, and further focused and narrowed onto the roll surface.

The laser irradiation head section 4 can be moved in parallel with the roll axis direction by rotation of the drive screw 5 in synchronization with the roll rotation. The laser beam can be pulsed at a predetermined frequency by a Q-switch or by a mechanical chopper. The pattern and depth of the surface roughness can be controlled by setting the frequency and output of this pulse, the number of rotations of the roll, and the moving speed of the laser irradiation head.

Carbide powder is sprayed toward the area irradiated with this laser pulse.

〔Example〕

The rolling mill used in the experiment was a small laboratory rolling mill, and the diameter of its rolls was 70 mm. A hoop-shaped material was continuously rolled using this roll, and wear of the roll and changes in roughness of the material surface were investigated.

The chemical composition of the rolls used in the experiment was C: 0.85% Si: 0.8 ton% Mn:% to 0.4 tons Ni: 0.15 hair volume% Cr: 2.9% by weight Mo: 0.29 hair volume% V: 0.01% by weight This is a commonly used component system.

The manufacturing process of the roll is as follows.

That is, after casting molten steel with the above components, the temperature is 1100.
It was forged at ℃ to a forging ratio of 3.5. Thereafter, a so-called norm treatment of heating to 950° C. and cooling with air was performed. This is heated to 800℃
After carbide spheroidization treatment for XtO time and 700°C I finished it to the final dimensions. Further, the surface layer was heated to 900° C. by induction heating, quenched in water, tempered at a low temperature of 150° C., and then the final surface was polished.

A roll subjected to such treatment exhibits a healthy structure in which spherical carbides are uniformly distributed in the Prussantite matrix.

While spraying cemented carbide powder 6 onto the surface of this roll 1, a pulsed C02 gas laser beam was irradiated using a mechanical chopper to roughen the surface to a predetermined roughness.

The supply phase of the cemented carbide powder 6 is 10 g/min, and the pressure is 2 kg.
/crrr' Ar gas 7 was blown from above as a carrier gas, and the excess cemented carbide powder was suctioned from below by a suction device 8 and dulled before being recovered.

The laser irradiation conditions are as follows: Laser power: 2KW Pulse frequency: 56KHz Laser beam diameter: 200℃m Energy density: 6.4X 10'W/crn'
Irradiation time per pulse: 13 JLsec Pitch of craters formed on the roll surface by irradiation: 170° C.m in both the roll circumferential direction and axial direction. WC, NbC, TiC as cemented carbide powder.

Rolls were manufactured using CrC, and using these rolls, a cold-rolled and annealed plate of low carbon An-killed steel with a plate thickness of 0.8 mm was temper-rolled at a reduction rate of 0.8%, and the plate surface was The reduction in roughness was investigated. The length calculated from the number of roll transfers is 50k.
Table 1 shows the results of evaluation based on the plate surface roughness reduction ΔRa after rolling m. :tSf diagram also shows a comparative example in which only laser dulling was performed without spraying of cemented carbide powder.

From Table 1, the excellent effects of the method of the present invention can be seen.

Table 1 [Effects of the Invention] According to the present invention, it is possible to provide a cold rolling roll with finely pitched and preferable unevenness by laser dulling, and to produce a roll that has extremely excellent wear resistance. The roll has a long life.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of a roll surface roughening processing apparatus that can suitably carry out the method of the present invention, and FIG. 2 is a cross-sectional view thereof.

Claims (1)

[Scope of Claims] 1. A method for laser dulling a rolling roll, which comprises performing laser dulling while spraying cemented carbide powder with a particle size of 3 μm or less onto the roll surface together with gas. 2. The laser dull processing method according to claim 1, wherein the laser dull processing is performed while vacuum suctioning the excess scattered cemented carbide powder. 3. Claim 1, characterized in that laser dulling is performed by irradiating the roll horizontally with a laser beam, spraying the carbide powder from above, and collecting excess carbide powder by suctioning it downward. Laser dull processing method described in section.