LU87193A1 - METHOD FOR MEASURING THE ABRASION RESISTANCE OF THE ROUGHNESS OF A METAL SURFACE - Google Patents

Description

ο _ ^ ^ -r C.JüOd 1 Ql Λ GRAND-DUCHÉ DE LUXEMBOURG '3 _ _ _ ...... l ................! .... ....... y ^ -,. , t iVL Monsieur le Mimstre \ du 7 ....... avril ........ 1..9..8.8 ................... ... wFaki of the Economy and the Middle Classes

Intellectual Property Service

Title issued ---- | ....... ||| LUXEMB0UR0

Invention Patent Application '........................................... .........----------------------------------------- ---------------------------------------------------------- ---------------------------------------------------------- ---------------------------------------------------------- ------------------------- (1) I. Request »

CENTER DE ...... RESEARCHES ...... METALLURGIQUES-CENTRUM VQQR ...... RESEARCH (2) IN ...... DE ..... METALLURGIE.association .... ..without profit-vereniging ...... zonder wins.ts..Q.gffl.e.rk., ... 4.Z., ... „xu! g ....... ..... Bryxfî..l..le.s „rEe.l.gi.au.e ... ,, ™ repr.é.s..en.té by Maître Alain RUKAVINA, lawyer-attorney , residing in ..... Luxembourg) i.QA.i ........ bouisYar.d ....... de ...... la ..... Eo.ir. e ................................................. ................................: ................. .......................................: .......... .................................................. .............

filing) this April 7 ...... 1900 ....... eighty-eight .......................... .................................................. ............._ (4) to 1.5. ·. 00 ........... hours, at the Ministry of Economy and Middle Classes, in Luxembourg: 1. this request for obtaining a patent for invention concerning: .... ...........................-........-............. .................................................. ..........................................-....... .................................................. .................................................. .................................................. .................. (5) "ProG.édé ....... de ....... me.s.ur.e ... .... de ... ia ..... r.é.sistanc.e ....... à ....... li..abras.ion ..... de— Xa ..- XiUgo.sXt.é ·· of a metal surface11 ___________________________________________________'__________________________________________________________________________________________________________________________________________________________ 2. description in language _____________ i.ânç.ai.se .................... .............................. of the invention in triplicate; 3. .//. two .................................. drawing boards, in triplicate; · 4. the tax receipt paid to the Registration Office in Luxembourg on .7 apr il — 15.8.8 __________________; 5. the delegation of power, dated ............ B .. £ .UX.S..1.1.! 8JS _____________________________________________ on March 2.2 „1.98.8 ___________________; 6. the successor document (authorization); declare (s) assuming responsibility for this declaration, that the inventor (s) is (are): (6)

Mpn.sieur ...: ... J..aC.qu.e..s ...... HAL.LE.UZ ..,. „..... 3..4 .., ...... r.ue ....... S.ur ...... l..es-Rorh.es..r .-. 4.5..4.0_ ¥ .isé .. ", ...... Es.l.gi4ue ____________________________________________________________________________________________________________________________________________________________________________________ claim (s) for the above patent application the priority of one (s) application (s) of (7) .......... patent of invention _________________________________ deposited in (8), _B_eJ.gjLqu.e __________________________ on (9) ................ April 8, 1987 ........... .................................................. .................................................. ........................

under N ° (10) _______ Q.8.ZQ.Q.â.Z.2 .___________________________________________________________________________________________________ in the name of (11) ....... dip.QSS, h ± ......... .................................................. .................................................. .............................

elect (elect) domicile for him / her and, if designated, for his / her representative, in Luxembourg_________________________ 10A, boulevard de la Foire_______________________________________________________________ (12) seeks (s) the grant of a patent for the invention for the object described and represented in the aforementioned appendices, with postponement of this issue to ..................... LL___________________________________________________________________________________month. (13)

The dipdsant / agent: ............................................. ..; ............................................... ..... q ____________________________________________________________ L ...... '(14) / I / 1 b-' '^ Π. Deposit Minutes

The above patent application has been filed with the Ministry of the Economy and the Middle Classes, ^ rvice of Property fateyeett ^ tte ^ uxembourg, dated: April 7, 1988 / ^ V \ Pt the Minister of the Economy and Middle Classes, at ..T..15 ..... Q.Û ....... hours iS Su - _ '_ ΛλΜ · - -: 1 The head of the intellectual property department, A68ÖÖ7 -_ ~ _I_ EXPLANATIONS RELATING TO THE FORMUÎÎWiiàgg ^ àT - 1 / ^ (1) if applicable "Request for certificate of addition to the main patent, to the main patent application No ...... [Jr. ... from ........... "- (2) enter the surname, first name, profession, address of the applicant, when the latter is an individual or your company name, legal form, address of the seat corporate, when the applicant is a legal person - (3) enter · “the surname, first name, address of the professional representative, industrial property council, with special powers, if applicable:" represented by .... ........ acting as the applicant "- (4) date of filing in all letters res - (5) title of the invention - (6) write down the names, first names, addresses of the inventors - or "indicate (separate designation (will follow)"), when the designation is made or will be done in a separate document, or the indication "not to mention", when the inventor signs or signs a non-mention document to be attached to a separate present or future designation - (7) patent, certificate of addition, utility model, patent europeri (CBÉ), international protection (PCT) - (8) State in which the first deposit was made J.Si & 3 »T (s ------ / '

S

Revendicnîlrn do! S nriorits c 2394/8704.

under k m dtfÿ-oo3 ¥ â, -

DESCRIPTIVE MEMORY filed in support of an INVENTION PATENT application in BELGIUM

on behalf of: METALLURGICAL RESEARCH CENTER - CENTRUM VOOR RESEARCH IN DE METALLURGIE, Association sans but Lucratif -Vereniging zonder winstoogmerk in Brussels, (Belgium) for: "Method for measuring Abrasion resistance of the roughness of a surface metallic".

✓ - 1 -

Method for measuring the abrasion resistance of the roughness of a metal surface.

The present invention relates to a method for measuring the abrasion resistance of the roughness of a metal surface, in particular the surface of a rolling mill cylinder, having a multitude of rough sites formed by means of a beam. intermittent laser.

5

It is known that the roughness of a stamping sheet, as well as the properties which depend on it, is conditioned by the roughness of the working surface of the rolls used to carry out, with a low reduction rate, the last rolling pass of this sheet.

10

A recent process, which is described in particular in patent BE-A-870,609, makes it possible to provide the surface of a rolling mill cylinder with a very interesting particular roughness. This roughness consists of a multitude of sites formed by an intermittent laser beam and re-left on the surface of the cylinder. Each site consists of a central crater surrounded by a generally asymmetrical bead which projects from the initial surface of the cylinder. This bead results from the very rapid solidification of the droplet of the molten metal by the laser beam and discharged towards the periphery of the molten zone. It is thus made of hardened metal, and therefore very hard, which allows to print corresponding hollows or valleys in the surface of the sheet during rolling.

The resistance of these beads to tearing and to wear, that is to say to abrasion during rolling conditions the consistency of the roughness applied to the rolled sheets.

'/ f - 2 - The objective of the present invention is to propose a method making it possible to assess, in a simple manner, the abrasion resistance of the beads formed by means of an intermittent laser beam in particular on the surface d 'a rolling mill cylinder.

5

According to the present invention, the method for measuring the abrasion resistance of the roughness of a metal surface having a multitude of rough sites formed by means of an intermittent laser beam and each comprising a central crater and a bead 10 surrounding said crater, is essentially characterized in that a cutting tool is applied to said surface, in that said cutting tool is moved along the surface along a trajectory which cuts through beads present on this surface, and in that the force to be applied to said cutting tool is measured to ensure said displacement.

According to the invention, the cutting tool is applied to the surface with a sufficient load so that it is not pushed up by the beads which it meets, but which is insufficient to make it penetrate into the surface. proper. This charge is preferably constant and oriented in a direction perpendicular to said surface.

When it moves along the surface, in accordance with the invention, the cutting tool thus successively meets the beads of the rough sites which are in its path.

In order for the cutting tool to continue its movement, the tip of the tool must therefore either tear off the bead or draw a groove therein, depending on the adhesion of the bead to the surface.

When the bead adheres poorly to the surface, a relatively small effort is sufficient to tear it from the surface without significant penetration of the tool into the bead.

- 3 -

On the contrary, if the base of the bead is well welded to the surface, the tip of the cutting tool enters the bead and traces a groove there. The force necessary for this purpose depends on the volume of metal to be crossed, as well as on the shape of the cross section of the bead.

5

The volume of metal discharged from the central crater and constituting the bead can in particular be expressed by the average volume Vç of the corresponding crater, which is defined, to within a factor, as being equal to the product of the depth of the crater by the square of its width L ^ at the level of said surface.

The section of the bead is characterized by a form factor HD / Ln

\ DO

which corresponds to the ratio between its height and its width measured along the path of the tip of the cutting tool.

15

According to the invention, the measured value of the force required for the cutting tool to pass through a bead makes it possible to assess the adhesion of the bead considered to the surface; it is thus possible to control the quality of the surface marking and consequently the adjustment of the parameters of the laser beam.

The invention will now be described in more detail with reference to the accompanying drawings, given by way of example, in which Figure 1 schematically shows the average profile of a rough site formed in the surface of a rolling mill cylinder by means of a laser pulse; the

Figure 2 illustrates the principle of the measurement method of the present invention; Figure 3 shows the average profile of a crater and a corresponding bead; the

Figure A presents reference curves of F ^ for different values of the Hg / L ^ ratio; and the

Figure 5 illustrates the influence of the width of the bead on the value 35 of F.

m t-: - ίχ -

Due to the importance of this application, the following description refers particularly to a rolling mill cylinder. It is understood, however, that no limitation results from the scope of the present invention.

5

Figure 1 schematically recalls the shape and profile of a rough site formed in the surface of a rolling mill cylinder 1 by means of a laser pulse. This rough site consists of a crater 2 surrounded by a bead 3, and it imprints in the sheet 4 an imprint 10 consisting of a valley 3 surrounding a plateau 6.

A series of such rough sites is illustrated, in section, in FIG. 2 which schematically shows the principle of the measurement method according to the present invention. The dashed line 7 symbolizes the initial level of the surface of the cylinder, with respect to which the successive laser pulses have given rise to the craters 2 and to the beads 3. These beads are generally not symmetrical with respect to the direction of the laser pulse which gave rise to them, in particular due to the movement of the surface during the marking operation. As a result, the shape and dimensions of the section of the bead are not constant all around the crater. It goes without saying that it is the most massive part of the beads which offers the greatest resistance to the advancement of the cutting tool.

The cutting tool 8 is applied to the surface of the cylinder with a load P; generally constant, and is moved along this surface in the direction of arrow F. The load P is such that the tip of the cutting tool 8 moves along the line in phantom 7. The trajectory of the tool of cutting intersects a series of successive sites, as shown in FIG. 2. The section of the tool in its plane of movement is such that the cutting edge starts a bead at its base, that is to say say in the plane of the surface, without the tool resting on the beads located upstream. In addition, the tool preferably has a cross section which is sufficiently narrow to only enter the sea, in width only one bead along its trajectory. In this way, the cutting tool 8 traces a groove in the profile of the roughened surface of the cylinder by clipping the successive beads 3 over a length, in the direction perpendicular to the plane of the drawing, which corresponds to the width of the cutting tool 8.

5 The representation of FIG. 2 corresponds to the case where the beads 3 are well welded to the surface of the cylinder and are not torn off by the cutting tool 8.

The diagram drawn in the lower part of FIG. 2 indicates the 10 variations of the force F required to ensure the movement of the cutting tool 8 in the direction d. This force is constant between two beads and corresponds to the friction of the tool on the smooth surface. In line with the beads, its value varies depending on the one hand on the volume Vg of the bead cut by the cutting tool 8, and on the other hand on the shape of the section of the bead characterized by the Hg / Lg ratio. These parameters have been defined above and they are illustrated in FIG. 3, which presents the average profile of a crater and of the massive part of the corresponding bead.

To characterize the abrasion resistance of a bead, it has been considered advantageous to relate it to the mean value F ^ of the force F corresponding to this bead; this average value is easily determined from the variation curve of the force F illustrated, by way of example, in FIG. 2.

25

Tests have shown that this force F ^ depends essentially on the volume occupied by this bead, this volume itself being practically equal to the volume Vg of the corresponding crater. In accordance with FIG. 3, this volume can be estimated, to within a constant factor, the value of? 30 product Pg. Lg.

When the size of the craters increases, the volume of the bead increases substantially to the same extent; this results in an increase in the corresponding force F ^, since the cutting tool must pass through an increasing volume of material.

* - 6 - t <

The tests also showed that, for the same volume of material, the shape of the section of the bead was of great importance. It is known that this shape can be modified by the action of a jet of gas, such as oxygen, during the surface marking process. In particular, the force F ^ increases with the average slope of the bead, expressed by the Hg / Lg ratio.

In FIG. 4, a series of reference curves has been shown giving the value of the movenne force F, in Newtons, as a function of the 2 5 m 10 volume P g · Lg, at 10. pm3, each curve being characterized by a constant value of the HD / LD ratio. All of these curves are re-

□ D

lative to textures whose beads are well welded to the surface. We can thus control the pullout resistance of the beads of a given texture for which the value of the ratio 15 Hg / Lg is known, by comparing the values of F ^ for this surface with the values of the corresponding reference curve.

The method of the invention also makes it possible to confirm the importance of the width Lg of the bead. If this width is such that the bead 20 extends beyond the zone heated by the laser pulse, it does not adhere well to the surface and has a low resistance to tearing. FIG. 5 indicates the values of the force F ^ relating to beads of widths Lg greater than 120 μπ ", that is to say that protruding quite largely from the heated zone. The low values of F, which are all located below the reference curve corresponding to the respective Hg / Lg ratios, indicate that these beads adhere poorly to the surface. Examination of these textures under a microscope reveals that the majority of these beads have been peeled off from the surface by the moving cutting tool.

30

The method of the invention makes it possible to specify the best tear resistance that can be expected from a determined texture and to show the limit values of the parameters of the craters and of the average beads, beyond which the texture does not is no longer sufficiently abrasion resistant. It also makes it possible to compare the behaviors of different textures.

Claims (5)

1. Method for measuring the abrasion resistance of the roughness of a surface having a multitude of rough sites formed by means of an intermittent laser beam and each having a central crater and a bead surrounding said crater, characterized in that that a cutting tool is applied to said surface, in that said cutting tool is moved along the surface along a path which cuts through beads present on this surface, and in that the the force to be applied to said cutting tool is measured to ensure said displacement. 10 2. Method according to claim 1, characterized in that said cutting tool is applied to the surface with a load which is sufficient so that it is not pushed up by the beads which it encounters during its movement , but which is insufficient to make it penetrate into the actual surface. 3. Measuring method according to claim 1 or 2, characterized in that the dimensions of the section of a bead are measured, in that the force required for crossing said bead is measured, in that the mean value of said force is determined during the crossing of said bead and in that, by comparison with reference curves corresponding to said dimensions of the section of the bead, the resistance to tearing of said bead is deduced therefrom. 25 4. Measuring method according to claim 3, characterized in that one regulates the conditions of formation of said rough sites so that the resistance to tearing of said bead, expressed by said average value, is at least equal to that which is provided by the corresponding reference curve. 5. Measuring method according to either of claims 1 to 4, characterized in that said metal surface is the working surface of a rolling mill cylinder.