AU650309B2

AU650309B2 - Abrasive on flexible backing and method of manufacture thereof

Info

Publication number: AU650309B2
Application number: AU90084/91A
Authority: AU
Inventors: Gustav Eisenberg; Wolfgang Dr. Falz
Original assignee: Ver Schmirgel & Maschf
Current assignee: VEREINIGTE SCHMIRGEL- und MASCHINEN-FABRIKEN AG
Priority date: 1991-01-05
Filing date: 1991-12-30
Publication date: 1994-06-16
Anticipated expiration: 2011-12-30
Also published as: KR920014565A; JPH0739575B2; ZA9235B; HK1011632A1; AU9008491A; ATE168611T1; DE4100167A1; DK0494435T3; JPH04304287A; DE59109030D1; KR0149510B1; EP0494435A1; ES2120952T3; DE4100167C2; EP0494435B1

Abstract

The object of the invention is to disclose an abrasive of the type in question, which, while avoiding the limitations which the abrasives of the prior art are subject to, calls for a lower proportion of abrasive grains and thus low costs but nonetheless ensures a performance comparable with conventional abrasives. This object is achieved in the abrasive according to the preamble of Claim 1 by these additives being present roughly in the size of the abrasive grain and having less hardness than the abrasive grain.

Description

i.-r u

JAUSTRALIA

AUSTRALIA

Patents Act 1990 65009

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: ABRASIVE ON FLEXIBLE BACKING AND METHOD OF MANUFACTURE THEREOF.

The following statement is a full description of this invention, including the best method of performing it known to me:-

I

II'

4 t I I 4 0 c~ I -2- Abrasives on a backing support are generally produced by application of a bonding agent such as animal glue or a phenol-formaldehyde resin to a flexible carrier such as paper, woven fabric or vulcanised fibre, in which the abrasive particles are distributed electrostatically or mechanically. After hardening of this so-called basebonding, the abrasive particles are held in fixed positions on the carrier. A second bonding layer, the so-called coating-bonding, which may likewise consist of an animal glue or of a resol (A-stage phenol-formaldehyde resin), mixed with fillers, is then applied. This second bonding layer bestows upon the abrasive particles their ultimate fixed anchoring to the carrier.

In bonding systems for abrasives, such as the afore-mentioned glues or resols, fillers of different types are utilised for various reasons. Thus, along with extending by the use of cheaper materials, such as chalk, other sought-after features are also i the improvement of the drying- and hardening-procedure involved, as well as improvement of the mechanical properties of the bondings.

Along with this, by the utilisation of so-called abrasive-active fillers such as, for example, cryolite or potassium fluoroborate, a greater or lesser degree of Simprovement, depending upon the particular materials used, of the abrasive performance is achieved, because these substances have a positive influence on the abrasive process.

According to the present state of the art, the addition to the coating-bonding is effected with materials in a very finely-divided state. Normally, the maximal workable size is determined by the usual mixing- and application-procedure.

According to the German Patent Specification DE-PS 3 112 954 C2, abrasive-active substances are also used in the form of granulates or pellets, in solid abrasive bodies.

L 3 Furthermore, it is known that mixtures of normal smeltcorundum having so-called high-performance abrasive particles, such as, for example, abrasive particles on the basis of aluminium oxide and zirconium oxide in an eutectic composition subsequently referred to as "zircon-corundum" or poly-crystalline aluminium oxide subsequently referred to as "sinter-corundum" are to be utilised in order to reduce the costs of production for highperformance abrasives. However, in this situation, special demands are made upon the particle-size distribution of the total mixture.

The problem to be solved by the present invention is the provision of an abrasive of the type under consideration, which does not suffer from the afore-mentioned restrictions and, in spite of this, possesses an abrasive performance comparable with that of abrasives known in the present state of the art, while having a smaller proportion of abrasive particles and consequently being cheaper to produce.

According to the present invention there is provided an abrasive on a backing support comprising: a carrier, a bonding agent containing a mixture of abrasive particles and additional particles applied to said carrier to form a base bonding layer; and a coatingbonding layer applied on said base bonding layer wherein the additional particles have approximately the same particle size as the abrasive particles but a lesser degree of hardness than the abrasive particles.

In an especially advantageous embodiment of the invention, the spatial arrangement of abrasive particles and additive substance is selected in such a manner that the points of the abrasive particles and of the additive substances all lie in one plane and thus come into effect simultaneously during the abrasion process.

ML

-4- The advantage of the abrasive in accordance with the present invention resides not only in a considerable saving of expensive abrasive particles but also, above all, in a significant enhancement of the abrasive performance.

Another advantage is the utilisation of a finely-divided, dried suspension of aluminium oxide, sieved to obtain the appropriate particle size, such as are used, for example, in the manufacture of ceramic abrasive particles having a Moh Hardness of 1 2, for use as an intermediate product in accordance with the German Patent Specification DE-PS 3 604 848.

According to the present state of the art, the application of additive substances, having particle sizes equivalent to those of the actual abrasive particles used, together with the coating-bonding, can only be effected with great difficulty, so that the abrasive in accordance with the present invention is advantageously manufactured by mixing the additive substances with the abrasive particles utilised and then distributing this mixture electrostatically or mechanically in the basebonding. In a further development of the invention, the two components may also be applied in two or more successive distribution procedures.

The superiority of the abrasive in accordance with the present invention, compared with those of the present state of the art, will be demonstrated by the following S examples, however without covering the entire range of the invention.

S 20 Example 1 A base bonding consisting of 50 Fercent by weight of a phenol-resol, having a phenol/formaldehyde ratio of 1 1.5 and a solids content of approximately percent by weight and 50 percent by weight of finely-ground chalk as additive substance having an average particle size of 20 pm, in an amount of 220 grams per EL~r-~ L.

square metre, was spread over a conventional polyester fabric by using the doctorblade coating method. A mixture of 33 percent by volume of normal corundum having particle size of P 36 (FEPA-Standard) and 67 percent by volume of chalk sieved to have the same particle size was then applied electrostatically in the known manner and subsequently dried and hardened in a conventional temperature program. The quantity of abrasive-particle/chalk applied was approximately .645 grams per square metre.

Lastly, the coating-bonding was applied by means of coating rollers, where this K coating consists of 50 percent by weight of a phenol-resol and 50 percent by weight of a synthetic cryolite having an average particle size of 15 [im. The quantity 1i applied was 460 grams per square metre. The coating-bonding was also hardened in the known manner.

i: Following this, the abrasive obtained in this way was rendered flexible and was produced as an endless strip 2000 millimetres in length and 50 millimretres wide.

Testing was carried out by rubbing against a rotating cylindrical rod, 30 millimetres in diameter, made from C 45, working material No. 1.0503 according to DIN 669 i: under a loading of 35 N, the abrasion being carried out over separate intervals each lasting for 5 minutes. The testing was discontinued when the amount of metal abraded per 5-minute interval fell below 50 grams.

0 An abraded amount of 1314 grams was achieved.

A comparison strip coated with pure normal corundum to the extent of 810 grams per square metre, under otherwise identical conditions, resulted in only 976 grams being removed by abrasion.

Example 2: An experimental strip was prepared in accordance with Example 1, with a mixture of 50 percent by volume of zircon-corundum of particle size 36 (AINSI) and percent by volume of chalk, sieved to have the same particle size, used as the additive. The quantity applied was 680 grams per square metre. Testing was carried out as in Example 1 under a loading of 40 N. The testing was discontinued when the amount of metal abraded per 5-minute interval fell below 100 grams.

An abraded amount of 2182 grams was achieved.

A comparison strip coated with pure normal corundum to the extent of 908 grams per square metre, resulted in only 1745 grams being removed by abrasion.

Example 3: An experimental strip was prepared in accordance with Example 1, however with ti a mixture of 60 percent by volume of cryolite granulate as additive, sieved to a Sparticle size of 36, and 40 percent by volume of zircon-corundum. Testing was 15 carried out by rubbing against a rotating cylindrical rod, 30 millimetres in diameter, 4 4 4 made from stainless steel (working material No. 1.4301, rolled and quenchhardened, ADW 2, DIN 17440 7/85). The abrasion was carried out for eight intervals each lasting for 5 minutes and the amount of steel abraded amounted to J 0 a total of 1203 grams. A comparison strip coated with pure zircon-corundum resulted in only 660 grams being removed by abrasion over the same period of time.

ML~ L I I -7- Example 4: An experimental strip was prepared in accordance with Example 1, however with a mixture of 55 percent by volume having a particle size of 36, and 45 percent by volume of a dried finely-divided aluminium oxide suspension, according to German Patent Specification DE-PS 3 804 848 C2, as the additive, sieved to the same particle size. The production of the abrasive strip was effected as in the foregoing Examples.

The already described testing against C 45 yielded an abrasive performance of 4293 grams under an applied pressure of 50 N; the comparison strip produced with pure zircon-corundum, under otherwise identical conditions, resulted in only 2165 grams being removed by abrasion.

The working life of the abrasive strip in accordance with the present invention thus Ilasted for 25 five-minute intervals compared with only 12 intervals for the comparison strip.

Example 5 i An experimental strip was prepared in accordance with Example 1, with a mixture K' of 50 percent by volume of sinter-corundum having particle size 36 and 50 percent by volume of crystalline magnesium oxide, having the same particle size, used as the additive.

Testing was carried out by abrasion against a rotating cylindrical rod, 30 millimetres in diameter, made from 42 CrMo4 (working material No. 1.7225). The applied pressure was 35 N and the abrasion was carried on for 20 intervals each lasting for 1 minute. The amount of steel abraded amounted to 642 grams. A comparison strip L -1i coated with pure sinter-corundum resulted in only 545 grams being removed by abrasion over the same period of time.

I

V I L L I I i

I

f r io tt, ISf EL.I _i

Claims

2. The abrasive according to claim i, wherein the abrasive particles consist of aluminium oxide and zirconium oxide in an eutectic composition.
3. The abrasive according to claim 1, wherein the abrasive particles consist of poly-crystalline aluminium oxide.
4. The abrasive according to any one of claims 1 to 3, wherein the abrasive particles are used on their own or in mixtures. The abrasive according to any one of claims 1 20 to 4, wherein at least a portion of the additional particles have a diameter from 50 up to 150 percent, of the average diameter of the abrasive particles.
6. The abrasive according to claim 5 wherein at least a portion of the additional particles have a diameter from 80 up to 120 percent of the average diameter of the abrasive particles.
7. The abasive according to claim 5 or 6, wherein the amount of additional particles having the same particle size as the abrasive is from 5 up to 90 percent by 30 volume, calculated with respect to the total amount of K abrasive particles and additional particles. c- i 10
8. The abrasive according to claim 7 wherein the amount of additional particles having the same particle size as the abrasive is from 20 up to 80 percent by volume calculated with respect to the total amount of abrasive particles and additional particles.
9. A method for the manufacture of an abrasive comprising the steps of: providing a carrier; applying on said carrier a base bonding layer comprising a bonding agent containing a mixture of abrasive particles and additional particles; applying a coating bonding layer on said base bonding layer; wherein said additional particles ar formed to have substantially the same size as said abrasive particles but a lesser degrtee of hardness than said abrasive particles.
10. Method according to claim 9 wherein said bond layer is formed by mutually spreading one of the abrasive particles and the additional particles on the bonding agent then spreading a layer of the other one of the abrasive particles and additional particles on the bond agent.
11. Method according to claim 9 wherein the abrasive particles and additional particles are mixed together and the mixture spread onto said bonding agent.
12. An abrasive according to claim 1 .substantially as herein described. Dated this 8th day of March, 1994. VEREINIGTE SCHMIRGEL-UND MASCHINEN- FABRIKEN AKTIENGESELLSCHAFT By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia E& LII i e- ABSTRACT OF THE DISCLOSURE Abrasive and method of manufacture thereof The present invention relates to an abrasive and a method for manufacture thereof. The problem to be solved by the present invention is the provision of an abrasive of the type under consideration, which does not suffer from the afore-mentioned restrictions and, in spite of this, possesses an abrasive performance comparable with that of abrasives known in the present state of the art, while having a smaller proportion of abrasive particles and consequently being cheaper to produce, while still guaranteeing an abrasive performance comparable to conventional abrasives. This problem is solved with the abrasive in accordance with the preamble to Patent Claim 1, by the presence of additives having particle sizes approximately the same as that of the abrasive but not having such a high degree of har.iess. .L i. i