LU86784A1 - Laser-powered surface marking for sheet mill roller - produces spaced laser beam impart points on turning roller, and develops craters and rims in desired pattern - Google Patents

Abstract

The surface of a roller forming part of a sheet metal mill is irradiated by an interrupted laser beam which, as the roller is turned, develops a series of microcraters. The positioning of the craters is determined by the rate of turning of the roller, the rate of interruption of the laser beam, and the traverse rate of the laser as it moves from one end of the roller to the other. During the formation of each microcrater, a jet of reducing gas is directed obliquely at the roller surface to produce an associated ridge which partly surrounds the crater. The dimensions of the ridge are determined by the jet force and direction applied. In a subsequent phase, the ridge formed is re-melted by a subsidiary beam to ensure complete adhesion with the roller surface. The resulting pattern is transferred to any sheets rolled, improving their ductility for stamping and their receptivity to superimposed coats.

Description

BL-4004 / ml

......., 86 7 8 GRAND-DUCHY OF LUXEMBOURG

~ ®reve ^ ^ Minister on February 23, 1987; 'J0 ^ L de I'Economie et des Classes Mcnennes _ Intellectual Property Service

Tllredan, rlS ................................... 1 Kg *) LUXEMBOURG

J3.8.SS j) eman (I of Invention Patent · '· ....................._.......... .................................................. - ................................................. ....... (1) I. Request CENTER DE RESEARCHES.METALLURGIQUES ..-..... CENïRUM VOOR RESEARCH IN DE. ... (2) METALLURGIE, non-profit association - vereniging zortder vinstoogmerk, ..... 47- rue..HQnt.Q.yex., .3 1040 Bruxelles, -Belgique ................ - ETFREYLINGER & E.MEYERS ing. Cons. ., owned _ind. ^ __ 46, _. rue du ... (3) ..... C imet i ère., ...... Luxembourg, - mandat aires ------- ----------------------------------------- deposit (s) this ________ February 23, nineteen hundred and twenty-seven ____________________________ (4) at ......... 3.00 p.m. ....... hours, at the Ministry of Economy and Average Classes, in Luxembourg: 1. the present request for obtaining a patent of invention concerning: ..... CYLINDER ..... FROM ROLLING MILL TO IMPROVED ROUGHNESS AND ..... METAL SHEET ..... PRODUCED (5) BY MEANS OF SAID CYL INDRE ._________________________________________________________________________________________________________________________________ 2. the description in language .............. French ................. of the invention in triplicate; 3. ............... a ............. drawing boards, in triplicate; 4. the receipt of the fees paid to the Luxembourg Registration Office, February 23, 1987 5. the delegation of power, dated. Brussels. ................................ on -20 February_1.987 ....

6. the pre-cause document (authorization); declare (s) assuming responsibility for this declaration, which inventor (s) is (are): (6d

Mr ....... Adolphe ..... BRAGARD., ...... domiciled ..... 76, Chemin ..des ...... Crêtes.,. 2B-4Q50 Esneux, .Belgium ... Mr, Jac ques HALLEUX, domic i li é 34, rue Sur-l es Roche s, B-4540 VisérBe 1g i as claimed) for the above patent application the priority of one (of) application ( s) of (7 | ............................................ ............................ ...................... .......... I ....................................... ................. filed in (8) _____________________________ / ______________________________________________ on (9) .................. .................................................. .................................................. ............................................------ ---------------------------------------------------------- ---------------------------------------------------------- - under N ° (10) .......................................... .................................................. ..................................... d ......-..... ..................... .................................................. —..........................: __ on behalf of 111) ................ .................................................. .................................................. .......... j______________________________________________________________________________________________________________ ...

elect (elect) domicile for him / her and. if appointed, for its representative, in Luxembourg .........................

.46, rue du cimetière, ..... Luxembourg ------------------------------------- ---------------------------------------------- (12) solIiciteQnt ) the grant of a patent for the subject described and represented in the abovementioned appendices.

with adjournment of this delivery to ............... drxr.hight _________________________________________________________________ month. (1? I

The depositor / agent: r ................— _______________________________________________________________________________________ (14 -

Jxf jj proc ^ s.verjjaj de j) £ p5t

The above patent application has been filed with the Ministry of the Economy and the Middle Classes. IntellectygUg Property Service ^ Luxembourg, dated: February 23, 1987 / V \ Pt · Minister of Economy and Classes Mo \ ennes.

at 15.00 ....... hours // Ud · i! \ i The head of the intellectual property department.

j- '' Aftsoor_yj; ,] _y ;! / __ EXPLANATIONS RELATING TO FORMb ^ Alfe * ^? fafeKir) / il j> ï \\ yd liet "Dciten je cl ^ 'Lificsr d'Adäihon5? Nwtai" *** mctpal- at main patent application No ........... / au. ........... "- Î2. Inspire ir. Nc-m. First name. PtuV-sior ..

1 -ί BL-4004 / ml * "Descriptive memorandum filed in support of an invention patent application for: ROLLING ROLL WITH IMPROVED ROUGHNESS AND METAL SHEET PRODUCED BY SAID CYLINDER.

Metallurgical research center-Centrum voor research in de métallurgie, non-profit association - vereniging zonder winstoogmerk, 47, rue Montoyer B- 1040 Bruxelles 4

1 T

C 2393/8702.

METALLURGICAL RESEARCH CENTER -CENTRUM V00R RESEARCH IN DE METALLURGIE,

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

Rolling mill cylinder with improved roughness and sheet metal produced by means of said cylinder.

The present invention relates to a rolling mill cylinder with improved roughness as well as to a metal sheet produced by means of said cylinder. It relates more particularly to a cold rolling mill cylinder intended to give a steel sheet a regular roughness which gives it a good appearance after painting and a good drawing ability.

We know that the surface of a steel sheet has a microscopic relief made up of valleys and plateaus between which there is a level difference of up to a few tens of micrometers. This relief constitutes the roughness of the surface of the sheet; it is applied to it by the cylinders of the last stand of the cold rolling mill. The roughness of a face of a sheet therefore constitutes the hollow replica of the roughness of the cylinder with which this face came into contact during the final rolling.

Already known, in particular from patent BE-A-870,609, a process for improving the properties of thin steel sheets. This process consists in creating, by means of an intermittent laser beam, a multitude of microcraters in the surface of a rolling mill cylinder. These microcraters are surrounded by a raised bead formed by ejection from the microcrater of the droplet of molten metal by the laser beam and rapid solidification thereof. These microcraters are joined so that their beads form a network of ridges surrounding a multitude of individual depressions. According to the patent BE-A-870,609 cited above, a microcrater has a dimension, generally a diameter, of between 30 and 250 micrometers in the plane of the surface and a difference in level of between 2 and 15 micrometers between the bottom of the depression and the top of the bead.

According to the mechanism briefly recalled above, a sheet laminated with such a cylinder will therefore present, on the surface, a network of communicating valleys which surround regularly distributed individual plates.

This network of valleys ensures good circulation and therefore a homogeneous distribution of the lubricant used for example for a stamping operation of the sheet. However, it has become apparent that if the tool pressure becomes too high, the lubricant is forced back into the network of valleys and there is direct contact between the tool metal and the metal of the plates on the surface of the sheet. . These are therefore exposed to abrasion and tearing, which leads to a risk of damage to the surface of the sheet. In addition, insufficient lubrication increases the risk of seizure during stamping.

In the case of the cylinders produced in the process recalled above, it is observed on the one hand that the microcraters have a substantially circular shape and on the other hand that the bead which surrounds them does not have a constant height. This irregularity is - * 1 i - 3 - due in particular to the rotational movement of the cylinder and to the action of an oxygen jet which rejects on one side a large part of the molten material. The present applicant has proposed various means for eliminating this irregularity of the bead and for increasing the depth of the microcrater and the adhesion of the bead. Such means are notably described in patent LU-A-86,694.

The present invention relates to a rolling mill cylinder whose surface has a roughness which is fundamentally different from that which has been described and produced up to now.

The rolling mill roll which is the subject of the present invention, the surface of which has a multitude of microcraters formed using an intermittent laser beam, is characterized in that the microcraters are provided with a bead on one part only from their periphery.

According to the invention, said bead extends at most over half of the periphery of the corresponding microcrater.

Also according to the invention, at least 30% of the metal constituting said bead are located inside the microcrater with which said bead is associated.

Still according to the invention, substantially all of the metal constituting said bead is located inside the zone of the cylinder heated by the laser pulse which gave rise to the corresponding microcrater.

According to a particular characteristic of the cylinder of the invention, the bead has a width which does not exceed approximately 100 micrometers and a height which does not exceed 30 micrometers, the latter being measured from the initial surface of the cylinder.

* / - 4 - ·%

The present invention also relates to a steel sheet rolled with such a cylinder and the surface of which has a multitude of uniformly distributed hollows, each of said hollows partially surrounding a plate.

Other features and advantages of the invention are indicated in the description which follows and which refers to the appended drawing, in which FIG. 1 schematically shows, in plan and in cross section, a microcrater formed in the surface of a cylinder according to the invention; and FIG. 2 schematically illustrates, also in plan and in cross section, the pattern printed in the surface of a steel sheet by a microcrater of FIG. 1.

FIG. 1 schematically represents a microcrater formed on the surface of a rolling mill cylinder according to the invention, by an intermittent laser beam adjusted in an appropriate manner. The cylinder 1 is symbolized by an axis of rotation 2, around which it rotates. Its surface is struck by an intermittent laser beam, each pulse of which causes the formation of a microcrater by a mechanism now well known. It will simply be recalled that at its point of impact, each pulse causes the heating of a certain volume of metal and, inside it, the fusion of a metal droplet. This molten metal is rejected radially towards the periphery of the heated zone, or possibly beyond this zone, where it forms a bead which solidifies very quickly.

In the present case, the conditions of the operation are regulated in such a way that the molten metal is, for the most part, rejected on one side. A bead 3 is thus obtained which partially surrounds a depression 4, all of these two components constituting a microcrater within the meaning of the present invention. In this figure 1, the broken line 5 marks the limit of the fused area. It can be seen that the molten metal is partly rejected outside the molten zone 5. The conditions are such that the molten metal adheres very well to the hot surface, and that there is no crack between the base of the bead 3 and the surface of the cylinder. Consequently, the bead does not risk "ii * i - 5 -" from being torn off during the rolling of a sheet. For a laser beam power of the order of 1.5 kW, the oxygen flow is adjusted so that the bead extends at most over a third of the periphery of the microcrater, the width L of the bead being less than 100 micrometers and its height h at most equal to 30 micrometers. , 30% of the metal constituting said bead must be located inside the microcrater. Since this same operation is repeated with each microcrater, it follows that the beads are not contiguous. The surface of the cylinder thus presents a multitude peaks 3 separated by a network of valleys, the bottom of which is essentially constituted by all of the depressions 4.

During rolling, such a microcrater prints in the surface of a sheet the relief shown diagrammatically in FIG. 2: the hollow 3 ′ corresponds to the bead 3 and the plate 4 ′ corresponds to the depression 4. The sheet thus produced has a multitude of 3 'insulated hollows, regularly distributed over the surface of the sheet. The dimensions of these recesses of course correspond to those of the beads which formed them.

When drawing such a sheet, the lubricant remains trapped in these recesses from which it cannot normally escape. If the tool pressure on the sheet is too high, the sheet tends to lengthen and the lubricant is partially expelled from the recesses located in the region concerned: it thus forms a lubricating film at the critical location. If, on the contrary, the pressure of the tool on the sheet is normal, the sheet slides while entraining the lubricant; it is therefore not scraped by the tools and it can be used for a more critical subsequent pass.

The hollows made in the sheet of the invention can be very small and be very tight, while remaining insulated. The relief of the surface of the sheet thus becomes very little pronounced, which contributes to improving the appearance of the sheet after painting.

Claims (7)

1. Rolling mill cylinder whose surface has a multitude of microcraters formed using an intermittent laser beam, characterized in that the microcraters are provided with a bead on only part of their periphery. 2. Rolling mill cylinder according to claim 1, characterized in that said bead extends at most over half of the periphery of the corresponding microcrater. 3. Rolling mill cylinder according to claim 1 or claim 2, characterized in that at least 30% of the metal constituting said bead are located inside the microcrater with which said bead is associated. 4. Rolling mill cylinder according to either of claims 1 to 3, characterized in that substantially all of the metal constituting said bead is located inside the area of the cylinder heated by the laser pulse which has gave birth to the corresponding microcrater. 5. Roller mill according to either of claims 1 to 4, characterized in that said bead has a width which does not exceed about 100 micrometers and a height which does not exceed about 30 micrometers. 6. Sheet steel cold rolled using a cylinder according to either of claims 1 to 3, characterized in that its surface has a multitude of hollows · uniformly distributed, each of said hollows partially surrounding a plateau. 7. Sheet steel according to claim 6, characterized in that said recesses have a width which does not exceed about 100 micrometers and a depth which does not exceed about 30 micrometers.