LU85463A1 - METHOD OF MARKING A CYLINDRICAL METAL OBJECT, SUCH AS A ROLLER CYLINDER - Google Patents

Abstract

The roll (2) is arranged in such a way that its axis is perpendicular to that of the laser beam (1), which is stationary. The roll is displaced along its longitudinal axis at the same time as being rotated about this axis. The disadvantages which are inherent in the methods employing a movable marking head, arising from faults in the marking head and from the variation in the length of the laser beam, are thus avoided. <IMAGE>

Description

* G 2315/8407 'METALLURGICAL RESEARCH CENTER -CENTRUM V00R' RESEARCH IN DE METALLURGIE,

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

Method of marking a cylindrical metal object, such as a rolling mill cylinder.

The present invention relates to a method / of marking a cylindrical metallic object, such as a rolling mill cylinder.

For purely illustrative purposes, the description which follows relates to the formation of a controlled roughness on the surface of a rolling mill cylinder, roughness which is then transferred to the surface of the rolled sheet by means of this cylinder. According to a method which is currently well known, this controlled roughness can be formed, that is to say marking the surface of the cylinder, by means of a beam of pulses 'laser,' which scans the surface of the cylinder.

v By its Belgian patent n ° 870.609, the present applicant has already proposed a method and a device making it possible to carry out such marking by moving, along a rotating cylinder, a marking head returning by focusing it on the surface of the cylinder, a laser beam emitted parallel to the axis of the cylinder by a fixed emitter.

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// A / "·" - 2 - From experience, however, it appeared that this process still had certain drawbacks essentially due to the use of a mobile marking head »associated with a fixed laser transmitter. It has in fact been found that the laser beam was not perfectly parallel, and that due to its divergence, it was increasingly difficult to maintain a focal point of adequate size on the surface of the cylinder as the marking head moves away from the laser transmitter. This defect can obviously be corrected by means of an appropriate lens, for example placed at the output of the laser transmitter, in order to make the beam parallel. This apparently simple solution ère turns out to be delicate, however, due to the degree; optical precision to achieve and maintain.

I On the other hand, the reflecting mirrors themselves have defects, accentuated by the heating under the impact of the energy beam, and introduce aberrations in the reflected beam.

The subject of the present invention is a method of overcoming these drawbacks.

It is based on the observation made by the applicant, that it is possible to achieve the relative movement of the marking head with respect to the surface to be marked while keeping the length of the trajectory of the laser beam constant and avoiding the use of reflecting mirrors.

To this end, the process which is the subject of the present invention is essentially characterized in that an energy beam is emitted whose axis intersects the axis of the cylindrical object under a substantially perpendicular incidence, in that one focuses said beam on the surface of said cylindrical object, and in that one puts it said cylindrical object in ·· translation along its longitudinal axis.

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According to an advantageous implementation of the method of the invention, the rotational and translational speeds of the cylindrical object are synchronized in such a way that the beam trace describes, on the surface of said cylindrical object, a trajectory predetermined, in particular a helical trajectory of determined pitch.

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According to a preferred implementation, the energy beam used a is a laser beam.

The attached figure illustrates the method of the invention applied to a rolling mill cylinder with a horizontal longitudinal axis.

A fixed laser emitter L emits a beam 1 in the direction of the cylinder 2 set in rotation according to the arrow 3. The axis of the beam 1 intersects the axis of the cylinder 2 under a substantially perpendicular incidence. The beam 1 / is focused on the surface of the cylinder 2 by means of a converging lens 4 having an appropriate focal distance. The cylinder 2 is placed in a cradle shown diagrammatically at 5 and capable of moving according to arrow 6. To ensure the desired marking 7 of the cylinder, the cradle is put in translation in a direction1, indicated by arrow 6, parallel to the longitudinal axis of the cylinder, and with a speed chosen in synchronism with the speed of rotation according to 3.

At a judiciously chosen point on the trajectory of the laser beam, it is possible to install a member, such as a perforated disc 8, capable of producing, by mechanical effect, pulses in the laser beam.

The method of the invention allows to operate with a constant length of the trajectory of the laser beam and to eliminate the use of reflecting mirrors. The optical system is very simple, since it can actually be reduced to a single lens. Finally, the method applies as well to continuous energy beams as to intermittent beams produced for example by means of an openwork interception member.

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Claims (3)

1. Method for marking a cylindrical metallic object, in particular a rolling mill cylinder, in which the surface of said cylindrical object rotated about its longitudinal axis is treated using an energy beam * , characterized in that the said energy beam is emitted in a direction which cuts the axis of the said cylindrical object! under a substantially perpendicular incidence, in that one focuses said beam on the surface of said cylindrical object and in that Ιΐοη puts said cylindrical object in translation along its longitudinal axis. “2. Method according to claim 1, characterized in that the rotational and translational speeds of the cylindrical object are synchronized in such a way that the beam trace describes on the surface of said cylindrical object a predetermined trajectory, in particular · a helical trajectory of determined pitch. / 3. Method according to either of Claims 1 and 2, characterized in that the energy beam used is a laser beam. Drawings: .......... 4 ..... page ^ ______: "5i„ .pages of which ...... 4 ...... page rie garde ...... ..3 ....... pag · of description ....... pE't s of claim ........... sfcrècé descriptif Luxembourg, le jt Ju; L m The representative : * ► Lie Alain P \ / èÂr, qf · 'r 1 hl Îh if / / fs; / \ _J /