JPS62158588A - Laser beam dull working method for cold rolling roll - Google Patents

Abstract

PURPOSE:To improve the hardness of the projecting part caused by a laser beam dull working and to easily obtain the roll that a wear resistance is given by performing a coating treatment of the fine powder of metal carbide in the specified grain size together with an adhesive on the roll surface prior to the laser beam dull working. CONSTITUTION:A roll is coated with the coating material containing the metal carbide powder <=3mum grain size and adhesive by a coater prior to irradiating a laser beam, then is subjected to laser beam dull working by a roll face roughening laser beam. The laser beam is adjusted in the prescribed beam by an optical device and diaphragmed by setting the focus on the roll surface. The laser beam irradiating head part 4 moves in the roll axial direction by the rotation of the driving screw synchronized with the roll rotation. The laser beam is pulsated in the prescribed frequencies and the depth and pattern of the surface roughness are controlled by setting the pulse frequency and output, number of roll rotations and the moving speed of the laser irradiating head 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the laser dulling force υ of cold rolling rolls, and more specifically, to roughening the surface to a desired pattern and unevenness depth by laser dulling. The present invention relates to a laser dulling method characterized by imparting wear resistance to a cold rolling roll or a temper rolling roll for metal materials.

[Conventional technology]

Surface quality is an important quality of rolled steel sheets.

Surface quality includes beauty, adhesion of paint and enamel, pressability, corrosion resistance, gloss, etc., and the geometrical shape of the board, that is, surface roughness, has an important influence on these properties.

The most common method of obtaining a metal surface with the desired surface roughness for each application is to pre-mill the surface of a cold roll or/and temper roll roll to a predetermined roughness.
In this method, a steel plate is rolled at a predetermined pressure using these rolls, and the roughness of the roll surface is transferred to the plate surface.

As a technique to replace the shot blasting and electric discharge machining methods that have been widely used in the past as methods for roughening the roll surface, an F method using a laser beam (hereinafter referred to as laser dull processing) has recently been proposed. For example, JP-A-56-160
892, JP 58-25557, JP 54-610
43, Japanese Unexamined Patent Publication No. 55-94790, etc. For details on how to irradiate laser pulses to both, please see till
However, the properties of the irradiated roll are not mentioned.

[Problem that the invention seeks to solve]

Laser dulling can efficiently form a well-ordered uneven pattern of mm 1 l on the roll surface. However, when temper rolling was performed using a roll whose surface had been roughened by laser dulling, it was found that the initial wear of the roll was quite large. In order to investigate the cause, the roll was sliced into rings and the cross-sectional structure and hardness distribution near the surface were investigated. As a result, it was found that a retained austenite phase, which is softer than the base metal, existed near the surface of the convex portion.

The present invention provides a method for laser dulling of a rolling roll using a pulsed laser, which strengthens this austenite phase, causes less wear during rolling, and therefore reduces roughness reduction.

[F-stage to solve problems]

In the present invention, when roughening the roll surface by performing laser dulling on the surface of a cold rolling roll, the roll surface is coated in advance with a coating agent containing a metal carbide powder with a particle size of 3 μm or more and an adhesive. This is a method for laser dulling a rolling roll, which is characterized in that the rolling roll is then subjected to laser dulling.

Metal carbides include WC, NbC, Tic, VC, and C.
rC is preferred.

[Effect]

When roughening a cold rolling roll by laser dulling, when a laser device irradiates the roll surface with a laser beam to roughen the surface, the irradiated part of the roll melts instantaneously. The roughness is increased by the formation of the four parts of the hole and the convex part as the metal scatters around and swells up.

In the method of the present invention, the roll surface is coated with a mixture of metal carbide powder and adhesive prior to laser dulling, so that the carbide powder is conjugated to the convex portions to form a hardened layer.

From the viewpoint of wear resistance, WClNbC,
Tic, VC, and CrC are suitable, and their particle Y-diameter is 3
It is suitable for forming a hardened layer on the convex parts after laser dulling if the ILm or less is mixed in the adhesive at a volume ratio of 30% or more, and this mixture is coated on the roll surface with a uniform thickness of about 5ILm. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention and its operation will be explained in more detail below with reference to the drawings.

FIG. 1 and FIG. 2 show an overall view of a surface roughening apparatus that can be suitably used in 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 output from the laser oscillator 3 is irradiated onto the roll surface almost directly in front of it via a plurality of mirrors. The laser beam is adjusted to 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.

Further, a coater 6 for applying a predetermined coating material to the roll surface and a drive screw 7 for the coater are provided.

Before being irradiated with a laser beam, the roll is coated with a coating agent that detects the metal oxide and the adhesive using a coater 6, and then subjected to laser dulling using a laser 3 for roughening the roll surface.

Next, specific processing cases will be shown based on examples.

〔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 wooden rolls, and wear of the rolls and changes in surface roughness were investigated.

What are the chemical compositions of the rolls used in the experiment?

C: 0-85 ton j-% Si: 0.8 ton! I1% Mn: O-4 city: n% Ni: 0.15 ton, '7% Cr: 2.9 ton! I)% M O: 0.29 i7i', :4%V:O,O1
It is a widely used component system.

The manufacturing process of the roll is as follows.

That is, after casting molten steel having the components listed in L, 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 carrying out carbide spheroidization treatment for XIO hours and 700°C x 1O hours, it was machined to predetermined dimensions. After machining, it was heated to 900°C, quenched in oil, tempered at 650°C, and machined again to 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 an overall structure in which spherical carbides are distributed in the Marsantei (Marsantei) J earth.

After cleaning and degreasing the roll surface, the roll surface was coated with a coating agent containing a gold J+jS>R compound with a particle size of 3ILm or less and a viscous and n agent using a machine described in "-", and then a mechanical chopper. A pulsed C02 gas laser beam was irradiated to roughen the surface to a predetermined roughness. WC and NbC as metal carbides.

TiC and CrC were used.

Laser irradiation conditions are: Laser power: 2KW Pulse frequency: 56KHz Laser beam diameter: 200 lm Energy density: 8.4X IOEi W/crn
Irradiation time per pulse: 13g Pitch of craters formed on the roll surface after 5ec irradiation: 70ILm in both the roll circumferential direction and axial direction.

Using this roll, a cold-rolled and annealed plate of low carbon Ai killed steel having a plate thickness of 9.8 mm was skin-pass rolled at a reduction ratio of 0.8%, and the low F of the plate surface roughness was examined. Decrease in plate surface roughness ΔRa after rolling 50kw using the length calculated from the number of roll transfers
The results of the evaluation are shown in Table 1. FIG. 1 also shows a comparative example in which only laser dull processing was performed.

Table 1 [Effects of the Invention] Before laser dulling, the surface of the roll is coated with fine metal carbide powder along with an adhesive to reduce the hardness of the protrusions caused by laser dulling and add wear resistance. -I
, it became possible to easily manufacture rolls.

In addition, although a roll coater method is shown in the examples as a method for coating the coating material, it goes without saying that various methods such as a spray method and a brush coating method can be used.

[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. 1... Roll 2... Roll rotation support device 3... Laser oscillator 4... Laser irradiation head 5... Drive screw 6... Coater

Claims (1)

[Claims] 1. A method for laser dulling a rolling roll, which comprises coating the roll surface with a coating material containing a metal carbide powder with a particle size of 3 μm or less and an adhesive, and then performing laser dulling.