USRE16755E - Pbocess of making sheet glass - Google Patents

Description

L. SHOWERS PROCESS OF MAKING SHEET GLASS "oct. 4, 1927 I Re. 16,755

Original Filed Jan. 1926 Reissued Oct. '4, 1927.

LEE SHOWERS, OF CHARLEROI,

GLASS COMPANY, A CORPORATIQN OF PENNSYLVANIA.

rnocnss or MAKING snnn'r GLASS.

Original ne.'1 ,so3,9sa, dated ember 19, 1926, Serial m. 81,949,411 Januar 1 s, 1926. Application 101- reissue filed August 16,-1927. SerialNo. 213,423.

/ I The inventidn relates to an intermittent method of making glass sheets. -It has one,

i of its largest fields of use in the making of I relatively thick colored glass, such asthat k v tural purposes in place of marble, but is not nown as carrai-a and used for architeclimitted to such'field, and may be employed to advantage. in the manufactureof trans-i parent thick glass,

' usual way. .Carrara-glass, eitherblack or,

orof. ordinary 'plate glass which is ground and polished in the 'white, is now made by casting. in thick'slabs from pots, and thenv grinding and polishmg theside which is to exposed to view, and; grinding (without polishing) the other side which isnot exposed to view. The present process is. designed to produce glass having a'fire polished upper surface reduiring'no grinding and polishing and a lower surface which is substantially true andfl'at so that no grinding is required. In those cases in which "a mechanically polished optically true upper surface "is desired, the amount of grinding necessary is reduced to'a minimum,

so that the cost is materiall lessened/as compared with glass produce by the usual.

method. -The form of apparatus preferably employed for producing the'rolled sheet is that shown and described inmy copending application, Serial Number 42,467. filed July 9, 1925. but the method is not limited to the use of that particularapparatus: Referring Cm'ediately following; the table 12 where the glass is liable'to sag dueto its'vplastic conto the drawings:

V Figure 1 is a vertical section through the rolling apparatus. And Fig.2 is a vertical section through the complete apparatus in a a very simple. diagrammatic form.

Referring to the drawings,-1 isa cast metal shell of large diameter which is in .efi'ect an annular casting table and; is sup-';

ported upon a pair of rolls 2 and 3: which extend through .the roll and' are..mounted in I suitable hearings supported upon a framemeans of the burners :work 4 at each side of the shell. 7 The shell is heated before the first cas ting operation by 5,; '-The shell may be lower'portion passes 7 thecasting 'operat1ons, th e cooling. effect of the atmosphere being relatively great upon to its delivery upon first part of the leer, the rest shell and the frequency of a shell of large diameter. Any other form of cooling means may, of course, be employed. Mounted in opposition to the 130- J riphery of the annular shell 1 is a. water cooled sizing roll 7, such roll beintag in a tilting framework 8 pivo to swing around the axis of. the'roll 3, so that the journaled' thickness of the sheet formed may bevaried.

by swinging the roll up or down.; This adjustme'nt may be accomplished by means of threaded arms 9 pivotal y connected at their lower ends to the framework 4and having their upper ends extended throughtnuts 10 I swiveled tilting framework 8.

In advance of the shell l-is awater cooled table 12 for supporting and chilling the lower surface of the glass sheet prelimina temperature controlling mean-sfs o arranged that the temperatureiof the leer decreases progressively from its inlet to its outlet'end. It is necessary tocool only the rolls in the of the rolls not requiring cooling and may' be spaced at-distances-a'part greater than that between the rollsatithe entrance end o'f'the leer and imdition. 1' y A. pocket 15,is

a ing closed'by means of end plates 17 which fit down between. the rolls and prevent'the bodvof glass from'escaping-laterally. The

pocket is of relatively large capacity so that it may receive an entirepot of glass weighing'a ten or more and capable of forming a sheet of feet in length depending upon the thickness of the sheet. The sizing roll 7 and the supporting rolls 2 and 3 are driven by suitable power means.

character illustrated passes the table l2' are also drivenat a rate the sizing'roll. and the continuous series through it Y between the shell in an extension 11 secured tothe i the rolls 13, whichrol s I "are artificially cooled. either hy-the circu-- lation of air or '18V glass anywhere from 40 to not showmpreferably. of the I anddescribed in my pending application. heretofore referred to.

The rolls 13 which receive the glass after it In'carrying out the operation, a pot of glass. which has been melted and fined 1n a pot furnace is carried to a position over the. pocket p tents emptiedinto the pocket. This is prefby means of a crane and the conerably done quickly,

the capacity of the pocket 15 being such as to receive the .entire pot of'glass before any substantial quantity is dischargedbetween the shell and the sizing roll, although the rolling out of the sheet may-be started, if desired,'as soon as the lower portion of the pocket is filled with glass. ,Better results are secured when the 15 the-pot as the rolling progresses.

.ing upward from 40 elongation of any bubbles 1n the glass," and ith a entire potof glass is emptied into the pocket -feet, ,sucli as is ordinarily employed in roll-' ing glass continuously from a tank.

The give high rate of rolling has'been found to with. less mechanical ream, with less better surface than where such rolling is done more slowly.

- With such high rolling-speed, the chilling effect of the sizing roll] upon the surface'ofthe glass is much reducedand only a very thin chilled skin, is formed." The marring effect of this rolhupon the supper surface of the glass is, therefore, much reduced and in some cases entirely eliminated, particularly in the making ofthick sheets of glass. Such sheets'con-tain a larg'e amount pf residual heat, and afterthesheetpasses the-.slzing roll, and as it is carried along-over the table '12. and the rolls 13,;the top skin is .up by the volume ofheat; in the lass and flows somewhat,- thus eliminating'tie marks 1 of the roll vand leavini the glass-with a fire softened po1ish. This fire polis is comparable in de:

" gree Wlth that secured in the ordinary plate glass polishin ioperat'ion, but'it is not opti call} plan'e and-true due to the minute irregularitiesoriwaves which are always formed when thefsurfa'cje of molten, glass solidifies.

. If an optic'allytrne surface is desired, it is, ftherieforre, necessary to grind and polishthe 'upper surface ofthe glass, but'this grinding and-polishing is reduced to a minimum by a the practice' of: the

' resent process, and there is a wide fieldfor t e use of white and black glass in which an optically "true surface is not require'd,xthe fire finish as secured by, the

- present process'being .suflicient for the pur pose. In sucheases, the glass produced by Q the present recess requires no grinding or I surface.

polishing eit er upon its upper. or its lower With colored glass for architectural work or for table tops, a lower polished 1 surfaceis not; necessary and the lower surface as produced by the present process is perfectly flat and true and relatively smooth.

The present process, therefore, produces a type of glass which is much superior to'the colored architectural glass heretofore proboth sides and in addition' required polish ing upon its upper side.

The high rate of movement of the glass sheet 18 over the rolls '13 prevents the glass {from saggingto any substantial degree between the rollers, even though the chilled lythi-n. However, thisspeed of movement must be continued for some time after the sheet'enters .the leer, otherwise, it will sag.- If this rate of speed were continued throughout the'entire annealing operation, "a leer of enormous length would be required and, the

present procedure is designed to avoid this necessity in so far as is possible, an unusually long leer. being requlred mgany case where sheets of unusual thickness'are to be pro duced, It will be understood in this connec= 9 tion that'the present process is designed to handle sheets both of unusifitl thickness, such v as those required for colored architectural glass and also for v the'production of plateglass of ordinary thickness, In either case, thexsheetis carried ahead at a high rateof speed until the glass has set sufliciently, or thelower' surface has set sufliciently to pro-- vent sagging. After the glass has so hardened and set, the-spe ed of rotation of the rolls inthe leer in the section occupied by the glass at that time is-reduced, and from such point on the sheet is given a speedgof movement which is progressively less-and .less. Means are, therefore, provided .for drivingthe sets ofrolls 13 in difi'erent sections of the leerat different rates of speed, so that the rate of movement of the sheet when it is an intermitte nt one, it is possible to run the different sections-of the leer at difierent speeds, such as would not be possible if a continuous sheet were being'form'ed. What-I claim lSZ V 1 Aprbcess of making glass consists in rolling laterally into a sheet at a relatively high rate of speed, carrying the sheet thus formed ahead on constantly shifting separated lines of transverse support, and then decreasing the speed of forward movement of the sheet and exposing it to a progressively decreasing temperature to anneal it. i 5 2. A process 'of making a glass sheet, which consists in rolling a body of molten glass laterally into a shect 'at a relatively high rate of speed, carrying the'sheet thus formed ahead on'constantly shifting sepasheet, which emerges from-the leer is only a fraction of a' body of molten glass skin on the lower side of-the sheet is-relativerated linesof transverse support, and then decreasing the 3 ed of forward movement of thesheet an exposing it to a progressively decreasing temperature to anneal it, 'I the speed of rolling being such, and the chilling'eflect of upon the sheet being reduced to a point such, that the residual heat of the glass after passing the-rolling means, substantially removes the marring eflfect of the rolling means upon the uppersurface of the sheet and giyes a fire polish or finish to such surface. 3. A process of, making a glass sheet, 16 which consists in rolling the sheet at a relatively high rate of speed from a body of the upper rolling] means through the subscribed my name this 15th day-of August,

LEE SHOWERS.

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