LU85267A1 - METHOD FOR IMPROVING THE SURFACE CONDITION OF A CYLINDER - Google Patents

Description

% "" Ί C 2295 / B403.

'METALLURGICAL RESEARCH CENTER -CENTRUM V00R RESEARCH IN DE METALLURGIE,

Non-profit association -Vereniging zonder winstoogmerk in BRUXELLES, (Belgium).

Method for improving the surface condition of a cylinder.

n —— 1 · 1 ............ '1'

The present invention relates to a method for improving the surface state of a cylinder using a corpuscular beam; focused light, such as a laser beam. This process applies in particular to rolling mill rolls or to rolls used in continuous annealing installations for steel strips. - I-i '

It is known that the surface condition, and in particular the roughness, ji · of the rolling mill rolls has a very strong influence on the surface quality of the metal sheets. A suitable roughness makes it possible to avoid sticking of the turns of a steel strip during * coil annealing; it also acts on the ability to form and coat sheets.

î he laughed

0 P

* - 2 - t -

Attempts have already been made to replace the random roughness of the cylinders, whether natural or obtained for example by shot blasting, by a controlled roughness whose distribution could be more easily controlled.

It has previously been proposed, in particular by Belgian patent No. 880.996, to carry out microperforations on the surface of the cylinders, by means of a laser beam, preferably intermittent, which causes localized destruction, by fusion, of the material constituting the surface.

This known process makes it possible to confer on the surface of the cylinder a remarkably regular and reproducible roughness in the form of micro-craters having the desired distribution.

The roughness obtained can however be affected by a certain anisotropy, due to the shape and profile of the microcraters. The shape of these micro-craters can indeed deviate significantly from the circular shape and take a more or less pronounced oval shape; this deformation is probably due to the relative displacement of the cylinder and the laser emitter, as well as to the speed of this displacement. This also results in a deformation of the transverse profile of the micro-craters, which no longer exhibits the symmetry of revolution desirable to guarantee the isotropy of the roughness.

i t t "l: To remedy this drawback, one could consider suppressing the relative movement of the various organs during the time of formation of each micro-crater. Such a solution would however pose various mechanical problems, likely to have unfavorable repercussions on the precision and regularity of the microperforations.

i l - i ψ “- 3 -

The present invention relates specifically to a method making it possible to remedy the aforementioned drawbacks without giving rise to the problems which have just been mentioned.

The process which is the subject of the present invention, in which the surface of the cylinder is treated by means of a corpuscular beam focused so as to form microperforations in this surface is essentially characterized in that a corpuscular beam is used polarized.

According to a particularly advantageous mode of implementation of the method of the invention, a corpuscular beam polarized along a plane substantially perpendicular to the direction of the movement responsible for the deformation of the microperforations is used.

When the microperforations are deformed in a direction parallel to the axis of the cylinder, a beam polarized along a plane perpendicular to this axis is used. On the contrary, r j when the microperforations are deformed in a direction perpendicular to a generatrix of the cylinder, a beam is used which is polarized along a plane containing or parallel to this axis.

'i

According to the invention, the degree of polarization of said n beam is adjusted so as to reduce or eliminate the deformation of the microperforations.

According to a first variant, the degree of polarization of said beam is adjusted as a function of the rate of deformation of the micro-I ** I perforations.

According to another variant, the degree of polarization of the said beam is adjusted as a function of the speed of the movement which is responsible for the deformation of the microperforations.

The method of the invention makes it possible to modify the distribution of energy over the section of the beam, so as to form microperforations of circular shape and of symmetrical profile.

“This results in a significant improvement in the isotropy of the roughness. By an appropriate adjustment of the intensity of the beam, it also makes it possible to act on the depth of the microperforations and on the volume of the bead formed around them.

i. | ji \ £

L

"I! | 1 - 1¾ /

Claims (5)

1. A method of improving the surface condition of a cylinder, in which the surface of said cylinder is treated by means of a corpuscular beam focused so as to form micro-* · perforations in said surface, the said cylinder and the beam being in motion relative to each other, characterized in that a polarized corpuscular beam is used. 2. Method according to claim 1, characterized in that one uses a beam polarized along a plane substantially perpendicular to the direction of movement responsible for deformations of the microperforations. 3. Method according to either of Claims 1 and 2, characterized in that the degree of polarization of the said beam is adjusted so as to reduce or eliminate the deformation of the microperforations. : î 4. Method according to claim 3, characterized in that the degree of polarization of said beam is adjusted as a function of the rate of deformation of the microperforations. -i -i 5. Method according to claim 3, characterized in that “the degree of polarization of said beam is adjusted as a function of the speed of the movement responsible for said deformation of the microperforations. iè; j _é-r: c: r c ....... λ z:}: i ...... A ..... de s S / il * t- '- · ·