US2780038A - Glass grinding and polishing method and apparatus - Google Patents

Description

Feb. 5, 1957 E. LAVERDISSE 2,730,038

GLASS GRINDING AND POLISHING METHOD AND APPARATUS Filed Sept. 7. 1955 2 Sheets-Sheet l Feb. 5, 1957 E. LAVERDISSE 2,780,038

GLASS GRINDING AND POLISHING METHOD AND APPARATUS Filed Sept. 7. 1955 2 Sheets-Sheet 2 GLASS GRINDING AND POLISHING METHOD AND APPARATUS Edmond Laverdisse, Auvelais, Belgium, assignor to-Les Glaceries de la Sambre, Societe Anonyme, Auvelais, Belgium, a Belgian company Application September 7, 1955, Serial No. 532,931 Claims priority, application Belgium September 8, 1954 10 Claims. (Cl. 51-110) The present invention relates to apparatus for grinding glass.

The invention provides an improvement in the feeding of abrasive to the iron, that is to say, the rotatory discoid tools employed for the grinding of the lower face of continuous glass plates or sheets, according to parent Pat ent No. 2,699,021.

It also concerns an extension of the improved feeding of abrasive to the rotatory polishing tools.

It is an object of the present invention to provide a method and means enabling the abrasive mixture introduced into the interior of the grinding or polishing tool to leave the said tool, wholly or in part without passing between the working face of the tool and the glass, so as to ensure continuity of the circulation of the abrasive mixture between the interior of the tool and the outside, regardless of the intensity of the centrifugal force acting within the tool.

The abrasive mixture which, without passing between the working face of the tool and the glass, leaves the interior of the tools supported by the successive beams of a machine for working the surface of a continuous sheet of glass, is directed together with the abrasive mixture which passes between the working face of the tool and the glass, by means of a common circulating device, towards a device with the aid of which the abrasive is graded in accordance with the grain sizes to be separated, and the graded abrasive mixtures are each separately fed, by means of a separating distributing device, which is preferably adjustable, to the different tools supported by the successive beams.

The present invention also concerns the devices for carrying out this improved feeding method.

A constructional form of a device designed in accord ance with the invention is illustrated by way of example in the accompanying drawings in which:

Figure l is a sectional elevation of the apparatus,

Figure 2 is a plan View on the line II-II of Figure 1,

Figures 3, 4, 5 and 6 are a plan view and axial sectional views of an iron constructed in accordance with the invention,

Figures 7 and 8 are an axial section and a plan view of a polishing tool designed in accordance with the invention, and

Figure 9 is an end view of a cording to Figure 1.

The tubular shafts 1 of the irons 2 are mounted in the upper and lower bearings 3, 4 fast with the beam 5, and rest through the hub 6 of a worm wheel 7 fast with each tubular shaft 1 on the lower bearing 4. The worm wheels 7 are driven with the aid of a common worm 8 by a part of the assembly acnited States Patent motor 9 mounted on the bottom of the beam. The tubular shaft 1 of each iron leads at one end into the central part 10 of the iron and at the other end into a collecting tank 11 secured to the bottom of the beam. Disposed within each tubular shaft 1 is a fixed tube 12 extending in fluidtight fashion through the base of the collecting tank 11,

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which supports it, and opening at its upper end, at which it is provided with a head forming a spreading cap 13, into the central part it of the iron. The tubular shaft 1 and the fixed tube 12 are separated from one another by an annular channel 14 of relatively large cross-section which leads at one end into the central chamber 10 of the iron and at the other end into the collecting tank 11. The coliecting tank ll preferably has an inclined base 15 and is provided at its lowermost point with a discharge pipe 16 leading into a reservoir 17. The abrasive mixture, which passes from the centre of the tools between the working surface of the latter and the glass to the outside is collected on collecting plates 54, which direct it towards the collecting tanks 55, and returns from the latter through the pipes 56, also to the reservoir 17. The latter is fed with abrasive mixture (water and fresh or used sand, or polishing composition) through a feed duct 18 and is connected at the other end to a pump 19, by which the abrasive mxiture is delivered through a pipe 20 into the grading tanks 21, 22, 23.

The abrasives, for example sand, in suspension in water, are graded by the speed of the current of abrasive mixture entering at 21 and are collected, the coarsest in the point 21 of 21, the medium-size in the point 22 of 22,

' and the finest in the point 23' of 23. Each of the points The grading tank 23 is provided with an overflow 27 for the discharge of the excess of abrasive mixture, for example, towards the collecting reservoir 17'.

For the sake of simplicity, only the distributor fed by 26 is illustrated in the drawings.

This distributor comprises a cistern 28 suspended in such manner as to be able to turn on a pin 29 controlled by any appropriate transmission system, for example, a pulley transmission system comprising pulleys 30, 31 and a belt 32. The cistern 23 is provided, for example, with two or more transfer pipes 33, 34 through which the abra sive mixture is distributed in a tank 35 divided by angularly displaceable partitions 36, 37, 33 (see Figure 2) into a number of compartments, in the present case three, 39, 4t), 41, the number of such compartments being determined by the number of tools to be fed on one beam. The base of each or" the compartments 39, id, 41 has an outlet 42, 43, 44 respectively through each of which the abrasive mixture is transferred into one of the funnels 45, 46, 47 each connected by a flexible pipe 48 to the feed duct 12 of the corresponding tool 2.

The distribution of the abrasive mixture between the tools 2 is adjusted by angularly displacing the partitions 36, 37, 38 in such manner as to vary proportionally the arcs a, b, 0 (see Figure 2) and thus the time for which it stays in the compartments 39, 5d, 41 below the pipes 33, 34 for the transfer thereof from the distributing cistern 28, which is actuated with a continuous rotatory movement.

The distributing tank 35 is provided with an overflow 49 leading to the collecting reservoir 17.

During the working, the beams 5 and the tools 2 supported thereby are actuated with a transverse reciprocating movement in relation to the longitudinal direction of the glass sheet 50. The tools also receive a rotational movement, by reason of which the central cup 51 of the tools, constituting the base of the central chamber 10 of the latter and provided with the projecting and dis ribstias bl de 5 m a ts 9 t abrasive mixture ed into the central chamber 19 a centrifugal force which varies with the speed of rotation of the tools or of the cup 53, if the latter receives a rotational movement independent of that of the actual tool 2, as is the case with the tool illustrated on the right-hand end of the beam 5 (Figure 1).

The feeding takes place as follows:

The pump 19 and the distributing cup being as sumed to be in operation, if the tools 2 are stationary (Figure 4) and their angular velocity is consequently zero, the abrasive mixture penetrates therein through the duct, 12, is spread on cap 13, falls into the cup 53, 52 and descends through the annular duct 14 into the collecting tank 11, whence it returns through the discharge pipe 16 into the reservoir 17. The abrasive in ture is taken up from the latter by the pump which delivers it through pipe 2% into the grading tanks 23., 2.5;, 23 whence itpasses through the parts 26, 23, 35, 45, and returns into the tube 12, and so on.

The abrasive becomes finer as it works. As it is sorted into constantly finer grades (see above) in proportion as it passes through the apparatus, it is thus fed to the tools which, considered in the direction of movement of the sheet, that is to say, from the first beam towards the last, work the glass and leave thereon traces of constantly decreasing depth.

When the tools 2 commence to work (see Figure 5) their speed of rotation increases progressively. Thus, the centrifugal force to which the abrasive mixture is subjected at 51, 52 or 53 increases, and in proportion with the acceleration of the rotation of the tools 2 or of the cup 53, a constantly increasing proportion of the abrasive mixture is directed towards the working plane of the tools, while a portion returns from the tool through the duct 14 towards the r e-circulation circuit described in the foregoing.

Finally, when the tools reach working speed (Figure 6), all the abrasive mixture entering the tools through the ducts 12 is directed towards the working plane of the tools.

The continuity of the circulation of the abrasive mixture effected in accordance with the present invention prevents very effectively the deposition of the abrasive in the piping, and even throughout its travel, and consequently all irregularities in circulation, including complete stoppages thereof and the dan rs resulting therefrom.

The circulating method and arrangement hereinbefore described are also applicable to polishing tools of the type illustrated in Figures '7 and 8.

These polishing tools comprise a metal disc or plate 56 fixed on the cup 51, 52 and supporting on its upper face an annular felt disc 57 having slots 68 and 69 formed therein in staggered relationship to one another. Assuming that the polishing tool rotates in the direction of the arrow x, the polishing composition (mixture of iron oxide and water) forced. through the cup 51, 5?. into the lower slots is thus introduced between the glass and the tool and thereafter passes partly through the outer slots 6? to feed the outer part of the felt discs 67.

Modified constructions are obviously possible without departing from the scope of the invention. For example, the feed device according to the invention may be used without the interposition of the grading tanks 2.1--23, and it may be used for supplying the felt polishing discs with water instead of the abrasive mixture.

In these two cases, the pipe it? may be provided with a shut-off valve 57 and a branch 58 connected by means of a flexible pipe 5'9 to a branch 6% having a shut-oil valve 61 in the piping 12. In addition, the pump 1? may be connected to the reservoir l? by a pipe 62 pro vided with a shutoff valve as and to a water reservoir (not shown) by a pipe as provided with a shut-off valve 65. When the valves 63 and 57 are opened, and the valves 65 and 61 are closed, the abrasive mixture is 4 l d o circulate a lisrsinbefm dessribsd the valve 57 is closed and, the valve 61 is opened, the abrasive mixture will pass through the tools and will return to the reservoir 17 through the pipes '16 and 56 without passing through the grading tanks 2l--23. When the valve 63 is closed and the valve 65 is opened, water, instead of abrasive mixture, will pass through the tools without passing through the grading tanks. This water, instead of being discharged into the reservoir 17, may be directed elsewhere, for example into an abrasive-recovcry tank (not shown), with the aid of appropriate branches (not shown) extending from the pipes 16 and 56, or by means of an orientable arrangement of the latter.

Furthermore, for the polishing, the grading tanks may be completely omitted and replaced, for example, by a conical reservoir, because it is unnecessary to grade the iron oxide which serves as an abrasive in the polishing. After having passed through the tools, this oxide could also be sent to the drain duct, or into a recovery device, with the aid of a piping such as 58, 59, 60, 61, 12 and 16, 56 described in the foregoing.

I claim:

1. The method of feeding abrasive mixture to the rotary tools of apparatus for working the lower face of a continuous glass sheet; said method comprising the steps of withdrawing the abrasive mixture from a reservoir therefor, supplying the withdrawn mixture to the interior said rotary tools axially of the latter, centrifugally distributing a portion of the mixture supplied to said tools between the working faces of the latter and the lower face of the glass sheet, and returning the remainder of the mixture axially from the interior of the tools to the reservoir in a continuous cycle, the relative proportions of the mixture supplied to said tools which are distributed between the working faces of the latter and the lower face of the glass sheet and returned to said reservoir, respectively, being determined by the rotational speed of said tools so that the rate of circulation of the mixture in said continuous cycle may be relatively great to prevent clogging of the latter even when the tools are rotating slowly and require a relatively small feed of mixture between their working faces and the lower face of the glass sheet. 7 H

2. The method of feeding abrasive mixture to the rotary tools of apparatus for working the lower surface of a continuous glass sheet; said method comprising the steps of pumping abrasive mixture from a reservoir thereof, grading the pumped mixture according to the grain size of the abrasive therein, distributing the graded mixture to the rotary tools. in accordance with the positions of the latter in the apparatus, feeding the distributed mixture to the interiors of the related tools axially of the latter, centrifugally spreading a portion of the mixture fed to the interior of each tool for radially outward passage between the working face of the tool and the lower surface of the glass sheet; while axially withdrawing from the interior of each tool the remainder of the mixture fed thereto, and returning to the reservoir, in a continuous cycle, said remainder of the mixture withdrawn axially from each tool, the used mixture that has completed its radial passage between said Working face of the tool and the lower surface of the glass sheet and any mix ture that has been graded in an amount exceeding the quantities that are distributed to the tools, so that the rate of passage. of the mixture in said continuous cycle is independent of the quantities that pass between the working faces of the tools and the lower surface of the glass sheet.

3. In apparatus for working the lower surface of a continuous glass sheet; the combination of tools rotatable about vertical axes and having working faces at the tops thereof, a reservoir for an abrasive mixture to be supplied to said tools, means continuously pumping abrasive mixture from said reservoir, means distributing the pumped mixture among said tools, means axially admitting the distributed mixture to the interior of each of said tools at the center of the latter, each of said tools having means centrifugally spreading a portion of the mixture admitted to the interior thereof for passage, in a generally radially outward direction, between said working face of the tool and the lower surface of the glass sheet, means axially discharging from the in terior of each tool the remainder of the mixture admitted to the latter so that the amounts of mixture passing between said working faces and the lower surface of the glass sheet are independent of the amounts admitted to the tools, collector means receiving both the portion of the mixture passing between the working face of each tool and the lower surface of the glass sheet and the remainder of the admitted mixture discharged axially from each tool, and return means carrying the mixture from said collector means back to said reservoir so that a continuous cycle exists for the mixture and the rate of flow therein can be substantial to prevent clogging even when only very small quantities of mixture are to pass between the working faces of the tools and the lower face of the glass sheet.

4. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 3, wherein said working face of each of said tools has a series of circular, spaced apart grooves therein concentric with its axis of rotation and radial grooves extending between successive circular grooves and disposed in circumferentially staggered relation.

5. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 3, wherein each of said tools has a felt pad in the shape of a broad annulus mounted on the top thereof to define said working face thereof, said pad having inner and outer, radially extending series of slots therein opening at the inner and outer peripheries, respectively, of said annulus, the slots of said inner and outer series being circumferentially staggered relative to each other.

6. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 3, wherein said means admitting the mixture to the interior of each tool includes a first pipe extending axially into the tool from the bottom of the latter, said first pipe having an upper open end within the interior of the tool and a radially outward directed flange at said upper open end across which the mixture is admitted from said first pipe, said means axially discharging the remainder of the admitted mixture from each tool includes a second pipe telescoping over said first pipe and of larger diameter than the latter to define an annular space between said first and second pipes opening, at its upper end, and said centrifugal spreading means includes an upwardly open, cup-shaped member at the upper end of said second pipe having impeller blades therein and rotated at a speed proportional to the rotational speed of the related tool so that, as the mixture is admitted across said radial flange of the first pipe, the admitted mixture is subject to the centrifugal action of said blades tending to cause radially outward fiow of the mixture from said cup-shaped member and to gravitational force tending to cause downward discharge of the mixture from said cup-shaped member into said annular space between said first and second pipes.

7. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 6, wherein said cup-shaped member and second pipe are fixed relative to said tool to rotate with the latter, and said second pipe acts as a supporting shaft for the related tool.

8. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 6, wherein said cup-shaped member and said second pipe are rotatable together relative to the related tool, and further comprising means rotating said second pipe in response to rotation of the related tool at a speed different from the rotational speed of the related tool.

9. In apparatus for working the lower surface of a continuous glass sheet; the combination of tools rotatable about vertical axes and having working faces at the tops thereof, a reservoir for an abrasive mixture to be supplied to said tools and having an outlet, pump means for withdrawing abrasive mixture from said outlet of the reservoir, pipe means receiving the abrasive mixture pumped from said reservoir, grading means receiving the abrasive mixture from said pipe means and operative to grade the mixture according to grain size, distributor means receiving graded abrasive mixture from said grading means and operative to distribute predetermined portions of the graded abrasive mixture for feeding to the related tools, means axially admitting the distributed mixture to the interior of each of said tools and the center of the latter, cach of said tools having means centrifugally spreading a portion of the mixture admitted to the interior thereof for passage, in a generally radially outward direction, between said working face of the tool and the lower surface of the glass sheet, means axially discharging from the interior of each tool the remainder of the mixture admitted to the latter so that the amounts of mixture passing between said working faces and the lower surface of the glass sheet are independent of the amounts admitted to the tools, collector means receiving both the portion of the mixture passing between the working face of each tool and the lower surface of the glass sheet and the remainder of the admitted mixture discharged axially from each tool, and return means carrying the mixture from said collector means back to said reservoir so that a continuous cycle exists for the mixture and the rate of flow therein can be substantial to prevent clogging even when only very small quantities of mixture are to pass between the working faces of the tools and the lower face of the glass sheet.

10. In apparatus for working the lower surface of a continuous glass sheet; the combination as in claim 9, further comprising first valve means in the outlet from the reservoir, a water supply pipe connected to the inlet side of said pump means, second valve means in said water supply pipe, third valve means in said pipe means between said pump means and grading means, by-pass ipe means connected, at one end, to the first mentioned pipe means between said pump means and third valve means and, at the other end, to said means axially admitting the distributed mixture to said tools, and fourth valve means in said by-pass pipe means.

References Cited in the file of this patent

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