DE1816206A1 - Electrically conductive abrasive article - Google Patents

Description

Patent attorneys DIpI. ing. F, Welcfcmenn, 1 Q TR 9 η R DIpI. Ing, H. V. 'eickmann, Dip !. Phys. Dr. K. rfpeir »IQIOZUO DIpI. ing. FA. Welckfnann, DIpI. Cham, ß.iluüer B Munich 27, MöhMr, 22

Case A / 329

NORTON ABRASIVES LIMITED, Welwyn Garden City, Hertfordshire,

England

Electrically conductive abrasive article

. ■ '■ «I» ¹ - »■' ^» ^ ■ ^ "'-' ¹ ^ ■"? - * ■■ * ■ - *

The invention relates to electrically conductive abrasive articles, in particular grinding wheels that are suitable for use in electrolytically assisted grinding »

It is known that for grinding cemented tungsten carbide as well as other electrically conductive hard materials, an electrolytically assisted grinding process noticeably lower the grinding cost by increasing the grinding speed as well as by reducing the wear rate of the electrically conductive grinding wheel able.

When performing this procedure, it is advisable to when the grinding wheel has a very high electrical conductivity, so that the main part of the work is done by a electrochemical removal of the workpiece is effected. Nonconductive abrasive particles are necessary, however, with them however, are present in smaller quantities. Their main function is therein, an interruption between the conductive part the disc and the workpiece to form an electrolytic removal of the workpiece via a suitable electrical

9.0 98-2 8 / 1.218. BAD o » _ÖlNAL

lytes, with the disk being the anode and the Workpiece represents the cathode.

Furthermore, the non-conductive abrasive particles are required to remove the decomposition products from the surface of the Remove the workpiece and resist wear and tear the inevitable contact with d8n> hard workpiece can occur. In the electrolytic grinding of cemented tungsten carbide, as well as similar hard materials, it is common to use diamond abrasive particles as the non-conductive abrasive particles maintained current densities low, then it is possible that a considerable amount of the work is done by the wheel, which acts as a conventional non-electrolytic grinding wheel. It is, however, a surprising fact that, if using electrolytic surfaces, softer materials, such as For example, tool steels or similar metals or alloys are ground, diamond abrasive particles are not have the same effectiveness as cheap conventional abrasives, such as molten aluminum oxide is used frequently, thereby avoiding the high cost of diamond.

Bs has also been found to be effective using inexpensive abrasive particles as the non-conductive particles electrolytic grinding of cemented tungsten carbide as well as similar compositions can be effected if high current densities are available for electrolytic decomposition. Usually, however, optimal conditions are difficult to achieve or maintain, the grinding speed can be considerably slower than when a wheel containing diamond abrasive particles is used.

, ^ v ίΜ »909828/1218

When diamond particles are used, the diamond-containing mass is usually to a relatively shallow depth the work surface is limited, one advantage of which is the disks containing no diamond is that they made entirely from the mass containing no diamond and completely up to the usual nozzle size a conventional grinding wheel can be used.

However, the grinding speed is of primary importance, as this is directly related to the ArbeltskoBten which m usually represent the greatest economic Paktor in relationship.

The following circumstances usually occur electrolytically assisted grinding on:

(a) Sine Diamanttei], hen mass grinds in effective catfish very hard conductive materials, but not softer materials such as steels.

(b) Partial diamond mass cannot work effectively

a combination of a very hard metal and steel, for example as a mounted μ tungsten carbide tool tip, su grind. A further processing step is necessary in order to first grind off or query the excess steel from the shaft and to expose the very hard tip for the action of the grinding wheel.

(c) A mass containing no diamond particles can in more effective catfish tool steels and similar materials to grind, however, has a very low efficiency when using very hard materials, such as for example cemented carbides.

BATH ORIGINAL 909828/1218

The aim of the invention is to create a grinding element, that works out in a satisfactory manner for each of these three Lets use categories.

The surprising finding was made that one of the like grinding element (which is usually a grinding wheel) can then be made when very small amounts of diamond be incorporated into a non-diamond containing abrasive mass. Preferably the diamond will look evenly distributed small spots on the work surface of none Abrasion compound containing diamond concentrated. The small diamond-containing areas can turn out to be more economical Extend in a manner through the body of the grinding wheel to the point where the wheel is most exposed; will. Further, the diamond-containing part may have the same composition as the non-diamond-containing part, with the exception that the required diamond content is a similar volume of a non-diamond containing material, that has a smooth grinding effect and an even one Abrasion results, replaced.

The present invention provides an electrically conductive abrasive article for an electrolytically assisted one Grinding with a diamond content in the consumable part Item less than 5.125 VoI-Ji.

The invention provides a grinding element composed of a conductive material, a non-diamond abrasive, and diamond, wherein the diamond is in a lesser volume amount than the non-diamond abrasive, the amount no more than 3.125 (preferably less than 1) VoI-Ji des makes up the entire usable part of the sole element. The diamond can be distributed throughout the usable part of the grinding element or preferably only on selected

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selected positions are available. In any case, the Diamond content preferably through the entire depth of the utilization «· barable part of the grinding element. The one that does not contain a diamond Abrasives can be any common abrasive consist «for example of aluminum oxide» zirconium oxide, Silicon dioxide or garnet »

According to one embodiment of the invention, there is a grinding element made available, the © ine Arbeltsoberfläohe has, the first fl & cnen has »'which from a vision made of one-way conductive material with a diet sanding agent, and second surfaces made from a mixture of a laiteaden Material with an abrasive that does not contain diamond exist. It is preferable to stop breathing for the first time represents a smaller part of the work surface arranged smoothly from each other *

The ®rford @ rlieti © Diamaatmenge canoe nle & ^ lgmw than 1 / tO be the amount "that a erfiMungsgetiäBe disc designed woräea can" AASS si © required for a common © Biaaaasitseheib © φ Dar addition ersielte advantage is, it completely Kami is used up to the stump size.

The following is explained in more detail by Hani d®F b @ ig3fögt @ n. Bi® figures 1 _S 2 mad 3 tend to be off

Fig _o 1! © igt a © siapfförasig® Spheite © with eln @ ra Bujpöhmes- w & n 153'Dn (6 ⁵³ ) and ®tn®r width ^ osi 25 «(1 ^K ) with e5.hem with <3ln & m DufohEsesser ^ on 31 es (1 1 / S ^S3 ) _O ^ s®ib © i on

12 raw C 1/2 ^S5 ) wad © ia © a Diarelma © The work part is di © rlngfuraii

909928/1218 bad original

(Soap it is a 25 Mi (1 ^B ) wide area, where the depth of use is 12 tm {1/2 ") * ie the depth of the recess corresponds to 1. · The body 3 öer sole consists of every electrically conductive one »Icein mass containing diamond soles * where at certain intervals» for example at 90 ° * an insert 4 is provided which extends across the surface 2. The insert 4 can have a width of 3 ma (1/8 ^N ) and have a depth of 12 mm (1/2 ") and consist of a dimension similar to that of the body 3 , with the assumption that part or all of the abrasive containing no diamond is diamond is replaced. A disk of this type is more effective. Sum grinding of both tool style and aiioh ferkittecem tungsten carbide.

FIG _e 2 shows a & sylindrlsolie Sohlelfscheibe having a diameter of 173 hm C7 ^w) "ad © iner width of 25" with a taefe 5) the Eissen Durciimesser of 50 mn (S ran (1 "") which worked !! If the kufier is the surface 6 representing the circumference, the practical depth of penetration being about 127 a (1 - 5 ⁿ ) in diameter-,

The body 7 4 © r disk is made of any suitable electrically-conductive and mass containing no diamond grinding, wherein in .Hbständen VOA, for example, 90 ° 'ai UEN circumferential herunr-' a Einsät "8 vorgeselaen 1st" the sicfe over the width of 25 mm (1 ") the disc · extends and even a © width Fon 3 rough (1/3 **) tarau Dinser linsats extend to su a radial depth gate 50 in (S") _# whereby a part of the not containing a diata level Abrasive or dlesee ga »se abrasive duroti Dtasaant is being replaced. This Scheits® is also ideally suited for grinding both factory steel and cemented tungsten carbide.

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1816208

There are many pre-feise methods on the required stakes 4 and 8 in oils Seheiben * & i © dwreäi ü ± e figures 1 vmu. 2 reproduced '^ earth ^ © inzusetsen. For example, Sehlifes know vjerden in a tesiE.es diamond © istha! Fe @ sid © disc naeli übli Qh®n methods, whereupon © in preformed 'Elasats aas © te "IHaBBm! T" entlxal,% share n & oh betemfc @ E <"; .ithod ©» © ing © kitfc @ t will.. The · putty can, if necessary, @ I © k *

Ee is ^ @ dooh

forraen eiasubringefta so that at

a uniform sfcgiskfcua? © rfealt®a wiM and k ^ ine visible Trenmsngislini® awisehesB. d @ n © iaffiaat = © niJ & alfceM @ S2 T®ilem unu den teinea Diaißaat effittmlt © iMien Tell © a mu movement of the tiiscSnsag; wSforend pract

Werhinuwäg'mit «tem no JDiasaasife © imfelialfesaaeia share sisli @mt © las Breit © vosi
ken. -Äu-f-dies® way wlva <έ ± η®
like si © for example

Insert bestefefe "If voa discs which Sieto s © uiitey TernfesicitiBg a tool o & @ r @ iss®s th (single point diamond) to Ulbricht @ lnmg of sp®siell <tm Kon 'doors kefstellea let dia possibility © laer ^ © rsturung * of the manufacturing plant veraieöea = Ein® auf dü @ & e Wsis © © j? «= witnessed the sight is the by Flg. 3 as given execution form where the Mamant-containing places 9 have been constricted before the * shaping of the halo and therefore have diffused at their bands into the KfSrper 10, which does not contain a diamond, over Ssli © ib © »

According to the invention, conductive abrasive particles can be traced Manufacture conventional full metallurgy methods. Should slices are produced «which work into special shapes Let «then Minnen with synthetic resin bound discs

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be fabricated «like this, for example, in the British Patent 991 14J is described.

The conductive material can be "a metal" such as Copper, bronze or silver, or graphite, as used in the manufacture of the well-known electrically conductive abrasive particles will be. The metal or graphite can not only serve * to provide the Oegenetand with electrical conductivity »but can also act as a binding agent, as is the case with the previously known elements that have a sintered metal bond or a graphite bond.

Unlike most cases where two abrasives are used in combination, the diamond content classify the abrasive elements according to the invention as the content of a secondary abrasive. The diamond content can be less than 2 vol-jH, based on the total usable Volume of the disk. In special cases tested, the content was actually only 0.2 vol-j6, based on the usable volume of the disc.

The following examples illustrate the invention without restricting it.

A resin bonded disk having the structure shown by Fig. 2 is made using one method operated as described in British patent specification 991 145 will. The main body of the disc is made of aluminum oxide (particles that pass through a sieve with a clear mesh size of 0.15 ram (100 mesh) pass), deoxidized copper powder and a phenol / formaldehyde resin and has the following composition:

9 0 9 8 2 8/1218 bad original

Aluminum oxide (particles passing through

a sieve with a clear one

Masememrelte of 0.15 b & i

(100 mesh) 22.5

Copper 33 * 5

Phenolic resin "* 34.2

Pores 10

Slots are made in the main body of the disc to a depth of 25 ram (1 ") and 3 mm (1/8") in diameter cut / to fit the inserts 8. These inserts are made from a mixture of the same alurainium oxide, des oxidized copper and phenolic resin, which are used to manufacture the Main body of the disc is used, but this mixture also contains a small amount of diamond (particles, which pass through a sieve with a mesh size of 0.15 mm (100 mesh)). Own the stakes the following composition:

Alumina 16.875

Diamond 5,625 VoX-g

Disoxidized copper 35.3 VoI-J *

Fhenoharz $ k, 2 VoI- $

Pores 10 VoI-Ji

The amount of diamond contained in the inserts 8 corresponds to 0.2 vol-jG. the usable depth of the »Seheibe.

Comparative tests are carried out using the disk produced in this way (disk A) and a similar disk which, however, does not contain any seeds 8 (disk B) _9. VTsröea these discs used under similar BeälEgangen _s sum electro-Iytischen grinding of tungsten carbide intestine, it is noted that the grinding speed b © i ^ yen esidung is the .Scheibe A- © »32 wm (0.0125") P ^ o Minute , while the sole elf speed when using the · Same construction is 0.07 mm

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BATH

(0.003 ") per minute is determined.

When using a metal-bonded disc which has 12.5% diamond in the working surface, a speed of about 6 mn (0.025 ^m ) per minute is achieved. Man. be seen dshei · ύ & Β ale Soheifoe A, which contains only 0.2 vol "# diamond in the irerwertbaren foil, works very well," said teerttctksiehtigt Mus, u & B the diamond content of the disc is relatively sxledrig.

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Claims (1)

a. tentaüaprche 1 "■■ Lislctrically conductive glass object for an electrolyte fe? «? aatgetialt in the usable fur of the object of than 3 * $ 125 2. Sehleifgegenstani naoh claim 1, $ & te «eh marked, that the btamantine content is less than 1Ji. 3 = grinding object according to claim 1 © düi »2, daduroh gelc © nii2sei © h» nets, UbM he made from © 1η @ ω electrical I © iteai © si material, eisi © ia keia®n Diamaafe containing Behleifmifct®! as much as the diamond consists of a smaller volume than the no diamond-shaped abrasive that Oer Bisaaant ctagfe u @ m -baren whole part of the distributed object therethrough. 5 «grinding object according to one of claims i - 3, gekemffieielmetj. that the. Diamond is only present in selected places <& e & usable part of the item. An abrasive article according to any one of claims 1-3 # characterized in that it has a working surface which has first surfaces which consist of a mixture of a conductive material with a diamond abrasive, and second surfaces which contain a mixture of a conductive material with an abrasive that does not contain diamond o_ 909828/1218 ^SAD - 12 ■ - - ■ 7. Abrasive article according to claim 6, characterized in that that the first areas together represent a smaller part of the processing surface and are evenly spaced from one another are arranged. 8. Abrasive article according to claim 3, characterized in that that the electrically conductive material consists of oraphite. 9 · Abrasive article according to claim 3, characterized by » that this is electric! conductive material consists of a metal, 10. Abrasive article according to claim £, characterized in that that it contains a synthetic resin as a binder. 11. Abrasive article according to claim 3 # characterized in that that it contains a metallic binder. 12. Sole object according to one of claims 1-11, characterized characterized in that it consists of a grinding wheel. 909828/1211