US1740005A - Grinding plate glass - Google Patents

Description

Dec. 17, 1929. J. P. CROWLEY GRINDING PLATE GLASS Filed April 10, 1924 Patented @en il?, i929 entran `s'ra'rlzs PATENT y OFFICE/ .mamen '.e. cnowtnr,

OF TOLEDO, OHIO, ASSIGNR TO LIBBEY-OWENS GLASS COMPANY, OF TOLEDO, OHIO, A .CORPORATION OF( OHIO enr'nnrnernmn Grass .appncauoafupd april 10,

rllhis invention relates to the art of grind-A ing plate glass, and more particularly-to a 4new and improved abrasive mixture and a continuousprocess for grading the same.

, Accoid11g .,t0.this invention a mixture `of substantially pure silica-sand and Crystalline garnet, suspended in Water, is first passed through a grading apparatus of the flotation type vvherein the materials settle out in a in series of distinct grades which are drained ed into suitable storage receptacles.v These diHerent grades of abrasive are maintained in suspension in the storage receptacles and a continuous circulation system which carries the abrasive ypast the several grinding ma;l` 'chines, and portions of the several grades,

successively from coarse to fine, are drawn from these circulating systems and fed to the contacting surfaces of the glass sheet and 2e the grindingtool. rllhe used material is col lected-'and 'pumped back to the grading sys: tem Where it is regraded and returned to the circulating system. The harder and heavier garnet, which does the greater part of the cutting in the first coarse grinding process, Will be deposited in the heavier grade of abra-4 sive, Whereas the softer and finer sand will predominate in the finer grade used for the smoothing process. ln this Way the entire grinding. operation is carried out rapidly and efficiently and a very smooth finish obtained'on the glass plate. lf the 'abrasive vmaterials are first mixed in the proper proportions and fed to the 'grading apparatus, the continuous grading process will be carried out automatically and the respective material distributed to the best advantage inl the several grades of abrasive mixture.

rihe invention will hemore clearly understood from the'folloaving detailed description of one typical system for grading and supplying this improved abrasive mixture. to a-series of-grinding machines. y yThe accompanying drawing sli'ovvs diagrammatically a grading and abrasive feeding system adapted to continuously supply the abrasive mixture to a plurality of grind- -ing machines;

At 1 is shown a grader of the flotation type comprising a series of separate compartments The unused ab pipe line 25.

1924. seri-a1 Np. 705,449.

2 to 7 respectively, the abrasive materials mixed with Water being fed into the first compartment 2' through a feed pipe 8. A screen 9 below'the pipe 8'serves to remove any excessively large-grained materials that may I vhave found their Way into the mixture. The

mixture in receptacle 2 flows over the partition 10 into the receptacle 3 wherein the glass level is slightly lower than in the rst receptacle 2. In the same manner the mixture .in

compartment 3 iiows over partition 11 into compartment 4 and so `on throughout the series. The larger grained and heavier materials will settle out in the first tank 2, the next heaviest materials Will settle out in compartment S and so on, the finest material suitable for use settling in the last compartment 7. The excess Water and suspended materials too fine for abrading purposes will pass out through the overovv pipe 12. It is to be understood that although six compartments are here shown, this nu-mber is merely illustrative and that any-desired number might be used. In the present mechanism three grades of abrasive are used in the grinding process.

The materials deposited in the rst two receptacles, numbered 2 and 3 respectively, are drained off through pipes 13 and 14 into a storage reservoir 15. In the same Way the material from tanks 4 and 5 is collected in a vreservoir 16 and the finest material `from tanks 6 and 7 is collected in reservoir 17. Sufficient Water is added in each reservoir to bring the mixture to the proper consistency, and a constantly driven agitator 18 is provided to keep the material in the reservoir in suspension. I

By means of a suitable pump 19 the heaviest grade of abrasive in tank or reservoir 15 is forced through a pipe line 20 Whichextends past each of a series of grinding machines 21. rasive in pipe 20 flows back and is discharged into the top of tank 15 as at 22. ln an exactly similar manner the medium grade of abrasive in tank 16 is forced through pipe line 23 the unused abrasive being discharged back into tank 16 at 24. In the same manner a supply of the finest grade of abrasive from reservoir 17 is maintained in the VA supply pipe 26 has valvedconnections Iat its upper end With each of the circulation pipes 20, 23- and 25, and atA its lower end isa'dapted to dischargetheabrasive. mixture from a spout 27 onto the upper face of the.

' glasssheet28 beneath'the grinding tool 29. The unusedlabrasive throivnoif from'the rotatin'g sheet and 'grinding tool, as Well asthe used abrasive 'Which has been vreduced insize by the grinding process, is collected in the housing 30 and drained through pipe 31 into a sump 32. From this sump'the abrasivemixture. is lifted vby' pump .through pipev '34; and discharged 'into the grading tank 2 at 35 along with thenew abrasive that may be addcd through feed pipe 8. Thisused abrasive then passes .through the series of grading tanks, and is properly distributed to theseveral reservoirs `15, 16 and 17 .The grading and feeding system briefly def scribed above is disclosed. more in detail and claimedin'm'y 'copending application, Serial 4No. 682,495,1iled December 24 1923z According 4to'` the present linvention a mi'Xf ture of silicasand, and crystalline garnet', linapproximately the proportions of' ten .parts sand to one part garnet, are mixed with Water 1 and fed through pipe'S-to the grading mechaf nism.- Thel garnet should be of a .grade that will pas'sthrough a 150 mesh screen. The

-v principal function ofthe garnet'is to perlform vthe rough grinding operation. The sand shouldl be no heavier .than Will-pass throughal() mesh screen, and a large pro-` portion ofit will be much finer than this'. The sand-used is substantially pure 'silica-` 'sand, which has a hardness sulicientto per- I yform the iin'al smoothing process fvvithout the aid of any harder abrasives such as emery or garnet. This sand performs the double func?v tion of operating asa cushioning medium for the garnetdurmg the rough and intermediate grinding operations, and Serves as the amount of the fine sand Will be carried down in these lirst tanks by the heavier garnet crysprocess.: f 1 Since cific grav1ty,'a large proportion 'of the garnet main abrasive agent inthefinal smoothing ,Willsettle out in the first grading tanks, and a very small proportion, and thatof the finest grade, Will pass through the series to-find Yits Way into the mixture usedlfor smoothing pur-- poses. The heavy sand will Isettle out infthe first tanks, and at the same time' a large tals. In-this Way the abrasivemixture in 'tank 15, used for the v rough grinding process,

I Awill 'contain most Aof the garnet, all of the heavy sand and a large proportion of lighter' sand. The medium grade of abrasive `in tank 16 Awill cons/ist of the intermediate grades of sand, Withgasmall percentage of the finer garnet. The finestabrasive, 'in tank 17,`u sed for the final smoothing process, Will be nearly all sand vof exceedingly'fine grains, l

the garnet has a relatively high spe- The garnet crystals are harder and sharper- 'than the sand 'and-morefefficientffor cutting away ythe glass in th'eflirs't rough4 grinding process.. At. the Sametime the' sand in the mixture vWill actas a cushioning agent between" the grinding tool and the glass to pref vent the garnet crystals froni`-grooving ytheglass too deeply." This cushioning Aaction of'. the sand Will be especially effective' in the' intermediate and inal grinding' processes Where it is quite importa-nt' to prevent the scoringof the sheet-Which would 'take place if the harder garnet crystals were usedalone. l

In systems'where garnet orfother hard abrasives areused for'the final smoothing process,

' from iinding veir Way into the smoothing process to preit anylarge grainsof garnet .quantity of ythisabrasive to'- the apparatus, otherwise theA surface of the glass Will become scratched or scored andv the sheetruined lin l -thepresent process the use oi a large (piantityv vot very. line silicasand v'for this smoothing abrasive willr quickly and effectively perform the smoothing operation and at the same time protect the Vglasstroml anyy garnet-particles.

,that Vmay findrthe'ir Way into this mixture, and serve as a cushion between the tool and the glass sheet to prevent the too rough grin'd-V ing action oftthis garnet. This smoothing sheet Without danger of yinjuring thesame. y

less violent smoothing action of the sandare mixture may be freely appliedto the glass It will beseenthat With this system the'` rapid grinding action of the garnet, and the .distributed thmugh the different Stages' of the grinding process so as to obtain the mostl "effectiveresults The proper sorting of the materialtakes place automati-cally, and the' lcli-f 'fereut grades of material-'may be fed Jfreelyto the apparatus Without any intermediate -ivashing processes, and the total grinding ieu `time Will'be much shorter than Would -be the 'case ifieither material Were used separately or' if` the 'two materials were fed separately smoothing the sheetwith fine silica-sand,

grinding plate glass, 'the iio abrasive actionof the garnet, and thenilmD grading the 4mixture by va settling'procesa Wherebythe coarse-rfgrad'sv contain most of the garnet, the grinding andsmoothing abra- "sives both being obtained from the same continuous grading process.l

-., 2.l In the art of grinding plate glass, the' process of suspending a mixture of silicasand and garnet in Water, grading the mixture by a' settling process, and successively.

fsa it is necessary to vuse a very accurate grading mageos feeding the grades, :fromy coarse to ne, to a grinding mechanism. i

3. In the art of grinding plate glass,` the process of suspending a mixture of silicasand and garnet in Water, grading the mixturebya settling process whereby the greater.

portion of the garnet is contained in the' coarser. grades, successively feeding the grades, from coarse to fine, to a grinding mechanism, collecting the used abrasive and returning it through the grading process.

4. lin the art of grinding plate glass, the process of suspending a mixture of silicasand and garnet in Water, grading the mixture by a settling process, whereby the coarser grades contain most of the garnet, and successively feeding the grades, from coarse to ine, to a grinding mechanism.

5.' in the art oi grinding plate glass, the process of suspending a mixture of silicasand and garnet in water, grading the mixture by a. settling process whereby the greater portion of the garnet remains in the coarser grades, again suspending each' grade of the mixture in Water and maintaining it in suspension Vby agitation, successively feeding some of each grade, from coarse to line, to

the grinding mechanism, collect-ing the used abrasive and returning it to the grading process.

Signed at Toledo, in the county of Lucas and State of Ohio, this 7th day of April,

JOSEPH l". CRVVLEY.

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