MXPA95005206A - Muelas super-abrasi - Google Patents

Abstract

The subject of the invention is a superabrasive grinding wheel with very hard particles and a metal matrix binder comprising additives "forming pores", in particular in the form of hollow ceramic balls. This applies above all to the use or rectification of glassware, in particular for sanding the edges of glass sheets.

Description

SUPER-ABRASIVE WHEELS OWNER: NORTON, S. A., a company of French nationality, domiciled at: 178, avenue Paul-Vaillant-Couturier F-93123 LA COURNEUVE, FRANCE. INVENTOR: Patrick MICHELETTI, French national, residing at: 6, rue Charles-Michels - F-93200 SAINT-DENIS, FRANCE.

DESCRIPTION The present invention relates to wheels called "super-abrasive". The wheels that are designated under this term are grinding wheels of very high abrasive power, based on very hard abrasive particles, especially diamond or cubic boron nitride, and an agglomerate that allows these particles to be retained and maintained in their place. . This agglomerate can be of three types: it can be a resin, especially a polyimide or phenolic resin. It can also be a vitrified agglomerate, in the form of a ceramic matrix of the alumina, alumina / silica or carbide / silica type. The agglomerate may also be based on a metal matrix, and it is to this third type of agglomerate that the invention relates more particularly, because it has a particularly advantageous mechanical strength. A constant difficulty of the grinding process is that of evacuating well the dust or other waste products generated by the operation. To do this, a medium is sent, in general water, in the direction of the wheel to evacuate those powders and also, of course, cool the wheel. However, the wheel that simultaneously attacks a whole portion of the surface of the article being treated, the cooling liquid has difficulties to progress towards the whole portion in the course of the treatment. Then, some accumulation of waste occurs. In the case of the treatment of glass articles, for example, the grinding is systematically accompanied by the formation of a layer of glass paste which tends to oppose the action of the grinding wheel and decreases the speed of the grinding operation. , forcing to operate in several passes. The present invention has for its object, an improved type of super-abrasive wheels with metal matrix binder that allows an improved solution of the problem of powders and other waste. The subject of the invention is a super-abrasive wheel based on very hard abrasive particles of the diamond or cubic boron nitride type and of a metal matrix binder, and which also contains adjuvants known as "porogens". Under this term, we mean adjuvants whose function is to create a certain porosity within the binder of the wheel. Until now, the contrary was rather the tendency to use metallic binders as dense as possible, this to seek to diminish as best as possible, the erosion of the wheel. However, it was found, surprisingly, that it was very advantageous indeed to have a certain "rate" of porosity in the metal matrix of the binder, because this porosity very significantly improved the problems of accumulation of the rubbish at the time of grinding. above, and even reach to increase the life of the wheel. These "porogenic" adjuvants should be selected according to the manufacturing process of the molars. In particular, they must be able to withstand the right pressure and temperature. This is the reason why some adjuvants are preferably used in the form of hollow ceramic balls, especially based on silica and / or aluminum oxide, such as alumina or mulite. The mulite is an aluminum silicate type 2Si02-3Al203. These balls are advantageously selected with an outer diameter between 1 miera and 3 mm, especially between 100 microns and 1 mm. Its walls preferably have a thickness between 2 and 8 microns, especially between 4 and 6 microns. Preferably, these porogenic adjuvants are added to the wheel in a proportion of 1% to 80% of the total volume of the wheel, especially between 5% and 50%, or approximately 30% of that volume. The mode of operation of these "porogenic" adjuvants is as follows: As the wheel wears out, the hollow balls that are found on the surface break and the surface of the wheel then becomes "hailed"; the glass paste can then accumulate in these holes without obstructing the progression of the grinding. In addition, the cooling liquid can progress continuously at the interface between the grinding wheel and the treated article and in this way, penetrate to the bottom of those holes, expel the glass paste or any other type of dust, which is evacuated from that way, to finally forward it to the bottom of each hole formed by a ball. On the other hand, the cooling liquid thus acts on a much more important surface than only the surface of the grinding wheel strip, allowing a direct cooling on a depth of the order of the diameter of the balls, which increases the more the efficiency of the cooling and decreases the wear of the wheel, due to this fact.Therefore it is understood that a great wall fineness of the hollow balls is advantageous, insofar as it facilitates their breaking, which is First of all, it looks for the invention in the invention, the rate of balls in the grinding wheel must be modulated according to the type of articles to be grinded, as regards the metallic matrix of the binder, it can be selected according to the applications The cobalt is widely used, but also the bronze, the silver that has the characteristic of being relatively ductile, the iron or the copper. add different additives to that matrix, especially as tungsten carbide, in order to increase the erosion resistance of the grinding wheel. With regard to the abrasive particles of , - the wheel, preferably correspond to 5% to 60% of the total volume of the wheel, especially to 10% to 30% of that volume. They can be presented in a round shape or in the form of needles, their size is evaluated with the help of a standard key of European abrasive manufacturers called FEPA: here, a grain size according to that key is selected, between 4 and 1182, which corresponds to an "average diameter" of particle of 4"" "" mieras at 1100 mm. Preferably, a grain size between 40 and 90 is selected. Here again, everything depends on the future use of the grinding wheel, the finest particles or abrasives that allow to obtain the most polished surface state of the piece that is going to grind. Advantageously, the grinding wheel according to the invention is used for the machining or grinding of glass articles, especially for grinding the 5 edges of glass sheets.

An example of the grinding wheel according to the invention is carried out in the following manner: a grinding wheel is manufactured according to the known manufacturing methods with 15% by volume of diamond particles with a grain size of 91 and 30% by volume of hollow balls of mulita of outer diameter of approximately 0.5 mm and wall thickness of approximately 5 microns, with a cobalt binder. The results are convincing: the grinding of the edges of the glass sheets is facilitated by an improved evacuation of the rubbish, an improved cooling of the grinding wheel that also produces an increase in the life of the grinding wheel of about 30%, in relation to a similar wheel without alumina balls.

Claims (10)

1. NOVELTY OF THE INVENTION Having described the invention, we consider it as a novelty and, therefore, claim as our property, what is contained in the following clauses. 1.- Super-abrasive grindstone based on very hard particles of the diamond or cubic boron nitride type, and of a metallic matrix binder, characterized in that it also contains "porogenic" adjuvants.
2. 2. Muela according to clause 1, characterized in that the "porogenic" adjuvants are hollow ceramic balls, especially alumina or mulita.
3. 3. Muela according to clause 2, characterized in that the hollow balls have an outer diameter comprised between 1 miera and 3 mm, especially between 100 microns and 1 mm.
4. 4. Muela according to clause 1 or clause 2, characterized in that the hollow balls have a wall of thickness comprised between 2 and 8 microns, especially between 4 and 6 microns.
5. 5. Muela according to any of the preceding clauses, characterized in that the adjuvants "porogens" are added at a rate of 1% to 80% of the total volume of the wheel, especially between 5% and 50%, by example 30% approximately of that volume.
6. 6. - Muela according to any of the clauses that precede, characterized in that the metal matrix of the binder is selected in at least one of the following metals: bronze, silver, cobalt, iron, copper.
7. 7. Muela according to any of the preceding clauses, characterized in that the metal matrix binder contains at least one additive, especially of the tungsten carbide type.
8. 8. Muela according to any of the clauses that precede, characterized in that the abrasive particles correspond to 5% to 60% of the total volume of the wheel, especially to 10% to 30% of that volume.
9. 9. Muela according to any of the preceding clauses, characterized in that the abrasive particles are in a round shape or in the form of needles, "r with a grain size comprised between 4 and 1182, especially from 40 to 90 approximately the normalized key FEP A.
10. 10.- Use of the wheel according to any of the clauses that precede, in the machining or rectification of glass articles, especially in the grinding of the edges of glass sheets. SUMMARY The subject of the invention is a superabrasive grinding wheel based on very hard particles and a metal matrix binder comprising additives "forming pores", especially in the form of hollow ceramic balls. This applies above all to the use or rectification of glassware, in particular for sanding the edges of glass sheets.