AN APPARATUS AND A PROCESS FOR GRINDING AN EDGE AND A GLAZING HAVING A GROUND EDGE

Abstract

An apparatus for edge grinding a glazing comprising a grinding wheel, rotatable about an axis, a groove in a circumference of the wheel and first and second orifices arranged on first and second sides of the plane of the groove, which form first and second jets of coolant directed substantially into the groove on first and second trajectories not in the plane of the groove. A corresponding process for edge grinding causes fewer sharp portions and fewer small fractures in the glazing edge than the prior art. A glazing manufactured by the apparatus or the process has higher edge strength than the prior art.

Claims

1. An apparatus for edge grinding of a glazing, comprising: a wheel suitable for grinding an edge of the glazing rotatable about an axis a groove in a circumference of the wheel such that a plane of the groove is perpendicular to the axis of rotation first and second orifices arranged on first and second sides of the plane of the groove, suitable for projecting coolant the first and second orifices being arranged to form first and second jets of coolant directed substantially into the groove on first and second trajectories not in the plane of the groove.

2. An apparatus according to claim 1, wherein the groove and the glazing are arranged to define a contact region and the first and second jets of coolant are directed substantially into the contact region.

3. An apparatus according to claim 1, comprising: a first series of orifices arranged on the first side of the plane of the groove to form a first series of jets of coolant second series of orifices arranged on the second side of the plane of the groove to form a second series of jets of coolant wherein said jets are directed substantially into the groove on trajectories not in the plane of the groove.

4. An apparatus according to claim 1, further comprising first and second containers for containing coolant and for supplying coolant to the orifices, arranged on the first and second sides of the plane of the groove.

5. An apparatus according to claim 4, wherein the first and second containers extend parallel to a half of the circumference of the wheel or less, more preferably a quarter of the circumference or less.

6. An apparatus according to claim 4, wherein the first and second containers are connected by at least one conduit suitable for supplying coolant from the first container to the second container, forming an assembly comprising a single inlet and no outlets except for the orifices.

7. An apparatus according to claim 1, wherein orifices are arranged in a range from 5 degrees to 45 degrees with respect to the plane of the groove.

8. An apparatus according to claim 1, wherein orifice diameters are in a range from 1 mm to 5 mm.

9. An apparatus according to claim 1, wherein the glazing is an automotive glazing having thickness in a range from 2 mm to 6 mm.

10. A process for manufacturing a glazing comprising providing an apparatus comprising a wheel suitable for grinding an edge of the glazing rotatable about an axis; providing a groove in a circumference of the wheel such that a plane of the groove is perpendicular to the axis of rotation; providing first and second orifices, arranged on first and second sides of the plane of the groove, suitable for projecting coolant; and arranging the first and second orifices to form first and second jets of coolant directed substantially into the groove on first and second trajectories not in the plane of the groove.

11. A process according to claim 10, comprising arranging the groove and the glazing to define a contact region and the first and second jets of coolant are directed substantially into the contact region.

12. A process according to claim 10, comprising: arranging a first series of orifices on the first side of the plane of the groove to form a first series of jets of coolant arranging a second series of orifices on the second side of the plane of the groove to form a second series of jets of coolant wherein said jets are directed substantially into the groove and on trajectories not in the plane of the groove.

13. A process according to claim 10, comprising: arranging first and second containers, for containing coolant and for supplying coolant to the orifices, on the first and second sides of the plane of the groove providing at least one conduit connecting the first and second containers, suitable for supplying coolant from the first container to the second container, forming an assembly comprising a single inlet and no outlets except for the orifices.

14. A process according to claim 10, wherein the glazing is an automotive glazing having thickness in a range from 2 mm to 6 mm.

15. An automotive glazing manufactured by the apparatus of claim 1, wherein an edge shape is U-shaped, C-shaped or V-shaped.

16. An apparatus according to claim 1, wherein orifices are arranged in a range from 10 degrees to 20 degrees with respect to the plane of the groove.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The invention will now be described by means of non-limiting examples with reference to the attached figures.

[0040] FIG. 1 shows an apparatus and a glazing according to the invention in cross-section in a plane containing an axis of rotation of a wheel.

[0041] FIG. 2 shows an apparatus and a glazing according to the invention in the plane of the groove, showing a groove and a glazing defining a contact region.

[0042] FIG. 3 shows an apparatus and a glazing according to the invention having a first series of orifices and a first series of jets of coolant.

[0043] FIG. 4 shows an apparatus and a glazing according to the invention having a second series of orifices and a second series of jets of coolant.

[0044] FIG. 5 shows an apparatus and a glazing according to the invention in isometric view and in cross-section in a plane containing an axis of rotation of a wheel.

[0045] FIG. 6 shows first and second containers for containing coolant, each comprising a series of orifices and connected by a conduit, according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0046] Although the invention is described herein with particular reference to an automotive windscreen, it will be understood that it has applications to other vehicle glazing, for example a rear window or a side window.

[0047] FIG. 1 shows an apparatus 1 for edge grinding of a glazing 10. The apparatus comprises a wheel 20 which rotates about an axis 2. A groove 30 in a circumference of the wheel is in a plane 3 perpendicular to the axis 2 of rotation. First and second orifices 41, 51 are arranged so as to direct first and second jets 61, 71 of coolant into the groove 30.

[0048] In an embodiment, first and second orifices 41, 51 are arranged on first and second sides of the plane 3 of the groove for projecting coolant. First and second orifices are arranged to form jets 61, 71 of coolant directed substantially into the groove 30 on first and second trajectories not in the plane 3 of the groove.

[0049] FIG. 2 shows an advantageous embodiment, where the groove 30 contacts the glazing 10 to define a contact region 31, and at least one orifice 41 is arranged to direct at least one jet 61 of coolant into the groove 30 to improve removal of debris and for further cooling.

[0050] FIG. 3 shows an advantageous embodiment, in which a first series of orifices 41, 42, 43, 44 are arranged on a first side of the plane 3 of the groove to form a first series of jets 61, 62, 63, 64 of coolant.

[0051] FIG. 4 shows a second series of orifices 51, 52, 53, 54 arranged on a second side of the plane 3 of the groove to form a second series of jets 71, 72, 73, 74 of coolant.

[0052] FIG. 5 shows a cross-section of the apparatus 1 for edge grinding a glazing 10. First and second containers 4, 5 are provided for containing coolant and for supplying coolant to the orifices, said containers arranged on the first and second sides of the plane 3 of the groove. The first and second containers 4, 5 extend parallel to a half of the circumference of the wheel 20 or less, more preferably a quarter of the circumference or less.

[0053] FIG. 6 shows an advantageous embodiment in which the first and second containers 4, 5 are connected by at least one conduit 6 suitable for supplying coolant from the first container 4 to the second container 5, forming an assembly comprising a single inlet 40 and no outlets except for the orifices.

[0054] Advantageously, an assembly having two series of orifices according to the invention can be retrofitted to an apparatus of the prior art, having only a first container and a first series of orifices. Two conduits 6 may be provided, so as to equalise pressure at both ends of the first and second containers 4, 5.

Examples of the Invention

[0055] Glazings were prepared according to the invention, by means of an apparatus having a grinding wheel comprising a groove, further comprising first and second series of orifices arranged on first and second sides of the plane of the groove. Orifices were arranged to form first and second series of jets of coolant, directed substantially into the groove on trajectories not in the plane of the groove.

[0056] The inventors have found that good cooling of the wheel and cleaning of the groove are achievable if orifices are arranged to form jets of coolant on a series of trajectories in a range from 5 degrees to 45 degrees with respect to the plane of the groove. Optimal cleaning is achieved in a range from 10 degrees to 20 degrees.

[0057] Optimal orifice diameters are in a range from 1 mm to 5 mm. Orifices can be holes in the walls of coolant containers, or may be nozzles, which can be unscrewed to allow easier cleaning of an orifice.

[0058] In comparative examples, edges of automotive glazing having thickness in a range 2 mm to 6 mm were introduced into an apparatus similar to the one described above, but having only one series of orifices. Automotive glazings manufactured by an apparatus and a process according to the invention were found to have fewer sharp portions and fewer small fractures than the comparative examples. Edge strength was higher than the prior art such that there were fewer breakages of glazing during manufacture and therefore higher process yield.