Grinding wheel for shaping flat glass

Abstract

A grinding wheel is suited for shaping glass, notably glass that is less than or equal to 4 mm thick. This grinding wheel has at least one abrasive portion formed of at least one metal binder and of diamonds distributed in the binder. The binder has a Rockwell B hardness of between 95 and 105 and is tungsten-based. The diamonds have a size of between 75 and 95 m and a concentration of between 2.2 ct/cm.sup.3 and 2.64 ct/cm.sup.3. Glass, in particular for shaping motor-vehicle glazing units, can be shaped with this grinding wheel, making it possible to achieve travel speeds greater than or equal to 30 m/min.

Claims

1. A grinding wheel, comprising: at least one abrasive portion comprising at least one metallic binder and diamonds distributed in the metallic binder, wherein the metallic binder comprises: from 58 to 75% by weight of tungsten; from 30 to 37% by weight of bronze, wherein the bronze comprises from 75 to 85% by weight of copper and from 15 to 25% by weight of tin; from 0.5 to 5% by weight of chrome; and from 0.5 to 5% by weight of nickel, wherein the metallic binder has a Rockwell B hardness of between 95 and 105, and wherein the diamonds have a size of between 75 and 95 m and a concentration of between 2.2 ct/cm.sup.3 and 2.64 ct/cm.sup.3.

2. The grinding wheel of claim 1, configured for shaping glass that is less than or equal to 4 mm thick, and/or configured for high-speed shaping.

3. The grinding wheel of claim 1, wherein the diamonds are coated with titanium.

4. A method for manufacturing the grinding wheel of claim 1, the method comprising: producing a mixture of the metallic binder and diamonds; heating the mixture to high temperature; pressurizing the mixture; and removing an assembly comprising the metallic binder incorporating the diamonds in a form of a grinding wheel from a mold.

5. A method for shaping glass, the method comprising: grinding a sheet of glass with the grinding wheel of claim 1 at a shaping travel speed greater than or equal to 30 m/min.

6. The method of claim 5, wherein a ratio between a rotation speed of the grinding wheel and the shaping travel speed is between 60 and 180.

7. A method for manufacturing a glazing unit, the method comprising: grinding a glazing unit with the grinding wheel of claim 1 at a shaping travel speed greater than or equal to 30 m/min.

8. A device, comprising the grinding wheel of claim 1.

9. The grinding wheel of claim 1, configured for shaping glass that is less than or equal to 2.6 mm thick.

10. The method of claim 7, wherein the glazing unit is a windshield, roof, or side window of a motor vehicle.

11. The method of claim 4, wherein heating the mixture comprises heating to a temperature of higher than 800 C. and pressurizing to several bar.

Description

EXAMPLE

(1) A grinding wheel according to the invention has been produced by inserting between the stainless metallic portions a mixture designed to form the abrasive portion and then by heating the assembly under pressure in order to have the various portions cohere, then by generating a shaping profile on the abrasive portion by spark erosion, the mixture designed to form the abrasive portion being formed of the following components: approximately 85% by volume of binder with the following composition (given by weight with respect to the binder); tungsten (powder): 61% bronze (powder): 37% chrome (powder): 1% nickel (powder): 1%,
the bronze being formed of approximately 80% copper and 20% tin, this binder having a Rockwell B hardness of approximately 100, approximately 15% by volume of diamonds (concentration of the order of 2.64 ct/cm.sup.3 in the abrasive portion of the grinding wheel), said diamonds having a size of 220 mesh (or 76 m), being covered with titanium (at a rate by weight of 6% of covered diamond).

(2) It has been observed that this grinding wheel made it possible to obtain a shaping travel speed of at least 30 m/min (the rotation speed of the grinding wheel being of the order of 60 m/s) while maintaining a good quality of the shaping seal (notably with a number of visible defects of less than 6 per decimeter) and while providing a service life of at least 50 km at least of shaped seal, with a brightening frequency every 25 to 30 glass elements (or every 112.5 to 135 m of shaped glass, the perimeter of the shaped glass elements in this example being 4.5 m).

(3) The glazing unit obtained by shaping by using the grinding wheel according to the invention can be used for example in a motor vehicle or transport vehicle, such as a windshield, a glazing unit for a roof or for a side window, etc.