US2757494A - Grinding and polishing glass - Google Patents

Description

1 2,757,494 GIN G AND POLISHING GLASS Charles Edouard Chaudron, Tamines, Belgium No Drawing. Application June 4, 1952, Serial No. 291,809 Claims priority, application Belgium June 12, 1951 18 Claims. (Cl. 5l--283) The invention relates to the grinding and polishing of glass, and is particularly concerned with the tools used to this end.

According to the today usual practice the grinding and polishing of glass is effected by means of tools called grinders moved in parallel relation to the surface of the Work and between which and said surface is interposed an abrasive substance, usually sand of increasing fineness as the Work is progressing, the polishing operation being effected or completed by means of felts and the so called rouge as abrasive medium. The abrasive medium is fed to the tools and felts in the form of a suspension in a liquid, usually water.

This known method presents several drawbacks amongst which may be named the difficulties encountered for regularly and uniformly feeding the abrasive medium to the grinding and polishing tools, especially where a continuous ribbon of flat glass is being ground or polished on both faces simultaneously, in which case the proper feeding in abrasive to the bottom tools is especially difficult to obtain. The main object of the invention is to remedy these drawbacks.

To this end, the invention consists in no longer using the abrasive medium in the form of a suspension in a liquid, but in the form of an agglomerate with an associated binder in order to obtain a coherent body to which may be imparted the shape of a body having definite sizes, for example a disc, suitable as a tool for performing grinding and polishing operations.

According to another feature of the invention, there are incorporated in the agglomerate materials which by nature are comparatively soft and, preferably, in addition, may be easily impregnated with a binder to impart to the agglomerate or shaped body some degree of resiliency and a good cohesion.

Such materials may be various kinds of fibres of animal, vegetal or mineral character, wood sawdust, paper or similar, substances.

As a binder, any material may be used which is adapted to perform the function of a binder. In accordance with a preferred embodiment, however, use is made of a natural or synthetic resin incorporated in a proportion as reduced as permissible to afford a suificient retaining action on the abrasive grains under the operating conditions to which the tool is subjected at the stage of the process to which said tool is related.

When use is made 'of a resin such as a vinylic or similar resin, the binder may be incorporated in a few number of per cent, for example 1 to 7%, these limits being for example only.

However, it has been found in practice that disc shaped bodies so formed enable the grinding and polishing of the glass to be effected with tools of moderate size and when use is made of moderate working pressures, but that when the size of the tools is increased and particularly when use is made of working pressures of high values, increased proportions of the binder are to be incorporated in the mixture.

Working pressures of high values are of particular interest in that they permit the duration of the operation to be materially reduced on the one hand, and on the other hand to obtain the necessary amount of abrasive substance for an accelerated grinding or polishing operation to be delivered by the tool itself.

trite States Patent 6 "ice According to this feature of the invention therefore, comparatively high proportions of the binder are incorporated in the mixture from which the grinding or polishing tools are made, these proportions increasing with the increase of the contemplated working pressure.

It has been found that satisfactory proportions are from 15 to 40% by weight of the mixture when the binder used is a vinylic resin and the filling substance is saw dust, the tools being of disc shape having a diametre from 30 to cms. and with a working pressure comprised between 5 and 15 kgs. per square decimetre. However these proportions may be varied according to the binder and/ or the filling material used.

in present practice of the polishing of glass, use is made of so called felts and experience has shown that high grade felts only that are formed with long fibers are economically usable.

When in producing tools in accordance with the invention use is made of fibrous material as filling component, low grade felts and even waste products may be used and still obtaining very good results in the polishing operation.

The following examples are illustrative of the invention.

Example 1 In the grinding-polishing of fiat glass on a test machine, on which the advance of the work was cms. per minute, with a linear velocity (mean rotation speed) of the tool of 4 m. per second and with a working pressure of 6 to 7 kgs. per square decimetre, the polishing was effected with disc shaped tools having a diametre of 30 cms. and the following compositions:

Percent (0) Sand (similar to the sand used at the end of the grinding operation as usually effected) 65 to 55 Sawdust 12 Polyvinyl acetate a- 15 to 25 (b) Rouge 60 to 50 Sawdust l5 Polyvinyl acetate 25 to 30 A finish was obtained quite similar to that normally secured with 25 tools as usually used (each including three rotating discs arranged around a rotating shaft) and with an advance of the work of 300 cms. per minute and a linear velocity of tool of 4 m. per second. In this test four sand tools (a) and 10 rouge tools (b) only were used.

Example 2 Under similar conditions as in Example 1, but with a working pressure of about 8.5 kgs. per square decimetre for the sand tools and 6.5 kgs. per square decimetre for the rouge tools, tools having the following compositions were used:

Percent (0) Sand (similar to the sand used at the end of the grinding operation as usually effected) 61 to 51 Sawdust Urea-formaldehyde (resin) 30 to 40 (d) Rouge 58 to 48 Sawdust 17 Urea-formaldehyde (resin) 25 to 35 Results comparable to those of Example 1 were obtained.

Example 3 In each of the above cases no appreciable heating of 3 the work has been experienced with either of the sand or rouge tools.

I claim:

1. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising rubbing the said broad surfaces of the sheets with a body of abrasive particles of substantially the same size agglomerated in coherent formation by means of a binder, said binder in cluding a resin, applied to the work through a fiat face thereof and retained under dry working conditions substantially in permanent contact with the work through substantially the entire area of the said flat face.

2. A method as in claim 1 wherein the resin is a synthetic resin.

3. A method as in claim 1 wherein the resin is polyvinyl acetate.

4. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising rubbing the said broad surfaces of the sheets with a body of abrasive particles and a filling material of soft nature in divided form agglomerated in coherent formation by means of a binder, applied to the work through a flat face thereof and retained under dry working conditions substantially in permanent contact with the work through substantially the entire area of the said flat face.

5. A method as in claim 4 wherein the filling material of soft nature in divided form includes sawdust.

6. A method as in claim 4 wherein the filling material of soft nature in divided form is a fibrous substance.

7. A method as in claim 4 wherein the filling material of soft nature in divided form includes felt waste.

8. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising pressing on and moving in parallel relation to such a broad surface of the sheets a coherent body of abrasive particles having free side surfaces and therebetween a fiat Working surface of one to four square feet and agglomerated by means of 15% to 40% by Weight of synthetic resin as a binder, said body being retained under dry working conditions in substantially permanent contact with the work through substantially the entire area of said flat working surface.

9. A method as in claim 8, wherein the agglomerated coherent body is applied to the work with a pressure from 50 to 150 kg. per square foot.

10. A method as in claim 8, wherein the agglomerated coherent body includes from 9 to 17% by weight of a soft material in divided form.

11. A method as in claim 8 wherein the agglomerated coherent body includes from 50 to 60% by weight of abrasive particles of substantially uniform size.

12. A method as in claim 8, wherein the work is moved With a linear velocity of about 75 cms. per minute, and the agglomerated coherent body is rotated with a mean rotation speed of about 4- m. per second.

13. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising rubbing the said broad surfaces of the sheets with a coherent body of an agglomerate of abrasive medium and a binder, applied to the work through a fiat face thereof and retained under dry working conditions substantially in permanent contact with the work through substantially the entire area of the said flat face.

14. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising rubbing the said broad surfaces of the sheets with a coherent body of abrasive particles agglomerated by means of a binder, applied to the work through a fiat face thereof and re tained under dry working conditions substantially in permanent contact with the work through substantially the entire area of the said fiat faces.

15. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising rubbing the said broad surfaces of the sheets with a body of abrasive particles and a filling material in divided form agglomerated in a coherent formation by means of a binder, applied to the work through a flat face thereof and retained under dry Working conditions substantially in permanent contact with the Work through substantially the entire area of the said flat faces.

16. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising pressing on and moving in parallel relation to such a broad surface of the sheets a coherent body of abrasive particles agglomerated by means of a binder, having free side surfaces and fiat external surfaces therebetween and retained under dry working conditions in substantially permanent contact with the work through substantially the entire area of a flat face thereof.

17. A method for grinding and polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising pressing on and moving in parallel relation to such a broad surface of the sheets a body of abrasive particles and a filling material of soft nature and divided form, retained in coherent formation by means of a binder, having free side surfaces and flat external surfaces therebetween and retained under dry working conditions in substantially permanent contact with the Work through substantially the entire area of a flat face thereof.

18. A method for grinding or polishing sheets of glass having substantially the same thickness over the entire area of their broad surfaces comprising pressing on and working in parallel relation to such a broad surface of the sheets a coherent body of abrasive particles having free side surfaces and therebetween a flat working surface smaller that one square foot and agglomerated by less than 7% of synthetic resin as a binder, said body being retained under dry Working conditions in substantially permanent contact with the work through substantially the entire area of said flat working surface.

References Cited in the file of this patent UNITED STATES PATENTS 538,917 Kaye May 7, 1895 749,551 Goehring et al. Jan. 12, 1904 774,612 Stead Nov. 8, 1904 917,937 Goehring et al Apr. 13, 1909 1,103,631 Stott July 14, 1914 1,183,947 Bradley May 23, 1916 1,401,831 Taylor Dec. 27, 1921 1,435,721 McIntosh Nov. 14, 1922 1,576,122 Webster Mar. 9, 1926 1,724,704 Fox Aug. 13, 1929 1,833,359 Fox et a1. Nov. 24, 1931 1,986,849 Pohl et al. Jan. 8, 1935 2,022,530 White Nov. 26, 1935 2,070,158 Elbel et al. Feb. 9, 1937 2,076,517 Robie Apr. 6, 1937 2,110,143 Ball et al. Mar. 8, 1938 2,189,733 Kistler Feb. 6, 1940 2,218,795 Kistler Oct. 22, 1940 2,249,278 Kistler u July 15, 1941 2,272,873 Kistler Feb. 10, 1942 2,294,239 Novotony Aug. 25, 1942 2,309,819 Benner Feb. 2, 1943 2,319,182 Van Der Pyl May 11, 1943 2,376,783 Kingman May 22, 1945 2,378,630 Hill June 19, 1945 2,404,192 Ries et al. July 16, 1946 2,460,367 Sharpe Feb. 1, 1949 2,527,628 Francis Oct. 31, 1950