US1729164A - Sheet-glass leer - Google Patents

Description

Sept. 24, 1929. FQT. FERNGREN SHEET GLASS LEER INVENTCHQQ Filed Deo. 14, 1925 hoch frncyre'?. M .9

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Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE ENOCH T. FERNGREN, OF TOLEDO, OHIO, ASSIGNOR TO LIBBEY-OWENS GLASS COM@- PANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO SHEET-GLASS LEER Application tiled December 14, 1925. Serial No. 75,270.

The present invention relates to improvements in an annealing oven or leer.

An important object of the invention is to provide a glass annealing leer with means whichiwill aid in maintaining a more uniform temperature condition transversely therein.

Another object of the invention is to reduce or more nearly equalize the stresses built up due to the natural contract/ion in a gradually cooling sheet of glass.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the drawings wherein like numerals are employed to designate like parts throughout the same,

Fig. l is a longitudinal elevation of the iml proved annealing oven, part of which is shown in section,

Fig. 2 1s a transverse sectlon taken on line 2--2 in Fig. 1, and

-FigLB is a transverse section taken online- 3-3 in Fig. 1.

Referring to the drawings in detail, the numeral 4 refers to a chamber in which the sheet ot' glass 5 lis continuously drawn and flattened in a manner more fully disclosed in the patent to Colburn 1,248,809, granted December 4, 1917.

In front of and attached to this chamber in horizontal alignment with the sheet as it passes therefrom is an oven or leer 6 of suitable size and design for annealing the sheet. The sheet 5 is advanced through the leer by a plurality of rotating rolls 7, upon which it 'may freely ride. These rolls are ordinarily made of asbestos cylinders 8, securely mounted upon a central hollow metallic core or shaft 9, this being a preferable construction capable of withstanding the heat within the leer. The ends of the hollow shafts 7 extend through openings 10 provided therefor in the side walls ot the leer and are supported in bearings mounted upon a suitable structure (not shown in the drawings) erected'along the walls ofthe leer. Each of the roll shafts are positively driven by being connected to some suitable form of group drive.

Owing to the continual contact of the sheet with the rolls, the roll peripheries might become roughened or worn to such an extent that the sheet would be scratched or marred from this condition if it were not for the fact that the rolls may be periodically painted or coated with a solution known in the art as a dope. This solution is applied to the rolls through openings 1-1 provided for this purpose in the side walls of the leer and forms a. perfectly smooth surface thereon.

In addition to the openings 10 and 11 in the. side walls of the leer, there is a third set of openings 12 that serve as a suitablemeans through which the leer operator may watch the sheet as it advances through the leer. It is apparent that unless these openings 10, 11 and 12'are ,properly closed or sealed after being used for their respective purposes, unequal heat losses will result along the side walls of the leer. A preferable means for meeting this situation, which is one of the objects of the invention, is to line each of the openings withl-iners 13, 14 and 15, and insert therein plugs 16, 17 and 18 made of suitable insulating material such as mineral or rock'wool. As the openings 12 are the ones most frequently used, these plugs may be hinged in some convenient manner to the liners 15.

The leer improvements covered by this invention are not necessarily limited to the Coliy burn process of drawing and annealing sheet glass, but are applicable to most any other process using either a horizontal or vertical leer.

The drawing and flattening chamber 4 has necessarily a relatively high temperature, and therefore the glass sheet issuing therefrom into the leer 6 is of a corresponding high temperature. .In order that the sheet will not sutt'er any sudden change in temperature as it leaves the chamber 4. the end of the leer adjacent thereto is heated by means of the burners 19 or by raising the gate 20, and thus permitting a portion of the heat in the chamber 4 to pass into the leer. Any fumes, etc. resulting from the use of the burners are carried oil' by l thereof which results in an unequal cooling oil'l or contraction of the sheet. This unequal contraction caused stresses to be built up within the sheet which being greater in some portions of it than in others, caused the sheet to snap where the stress was the greatest. Since a greater amount of heat in the leer is lost at its sides than at the center, by radiation or by the tanning eiect of air currents on the outside, it is believed the sheet cools off faster or contracts at a greater rate along the areas or zones in proximity thereto than in the central zones. It is within these side zones that most of the breakage seems to occur. So it is an object of this invention to equalize the temperature conditions within the leer as far as possible by insulating` it in a suitable manner.

As illustrated in the drawings a preferable construction for insulating the leer is shown in Figs. 2 and 3. A layer of fire brick 22 is laid upon the ceiling 23 of the leer at the end next to the chamber 4. Further down the leer toward the cooler end the central part of the layer 22 is eliminated. leaving the portions 24 and 25 covering the leer ceiling at the sides only, and finally at the extreme end of the leer the portions 24 and 25 are eliminated, thus leaving the leer ceiling exposed to the outer atmosphere. On top of and along the outer edges of the fire brick layer 22 a layer of insulation 26 (preferably rock or mineral wool) is placed, which laps down over the upper portions 27 of the leer side walls. This insulation extends approximately throughout threeuarters of the length of the leer. Embedde in and on top of the insulation 26, approximately above but inside of the joint made by the ceiling and side walls ofthe leer, is a strip of insulation 28 whichprovides for additional thickness of insulation at this point. f

Another advanta e of this improved leer is the fact that it is ivided iirto two portions -by the aille wall 29J The wall above the sheet is in t e form of a damper 30 operated from the outside by the lever 31. Below the sheet at the bottom thereof is another damper 32 preferably made in three separate sections 33, 34 and 35. The section 33 is operated by the lever 36 section 34 is operated by lever 37; and section is operated upon a sleeve around the shaft 38 by the lever 39. The initial conditioning of the sheet before being annealed is therefore done in the smaller portion of the leer, the temperature of this portion of the leer being controlled by the burners 19 and the proper manipulation of the dampers 30 and 32, and the gate 20. It is quite important that the gate 2O and the damper 30 be properly adjusted as they control draft and temperature conditions of that part of the leer above the sheet by checking the flowing away of the heated atmosphere. This gate and damper assist in increasing the depth of the protective pressure of the heated atmosphere around the sheet, maintain a more coniined atmosphere atv the entrance to the leer, and make possible, in conjunction with the damper 32, the separate maintenance ofa heat adjusting compartment at the entrance to the leer.

Further down the leer toward the cooling end is another damper 40 comprising preferably three separate sections which are operated in the same manner as the damper 32 by the levers 44, and 46. By the proper manipulation of the dampers 30, 32 and 40, and the gate 20, the heated air currents within the leer may be localized longitudinally along the side walls or center thereof, or both. After the sheet has been annealed it passes onto a conveying or cutting table 47 where it is .finally cut into sheets of required lengths.

It is believed that by insulating the leer as described and by the proper adjustment of the dampers, an ideal annealing condition within the leer will result, and thus eliminate considerable breakage. Glass for comlnercial use, having been properly and thoroughly annealed, in a leer provided with the improvements covered by this invention, may ble less subject to fracture from sudden shocks than glass annealed in an ordinary leer.

It is to be understood that the form of the invention herewith shown and described is to be taken as the preferred embodiment of the same, and that various changes in the shape, size and arrangement of parts ma be resorted to without departing from t e spirit of the invention or the scope of the subjoined claims.

Claims:

1. An annealing oven, conveying means therein for advancing a-sheet of glass longitudinally through the oven, and a covering of insulation positioned upon the upper corners only of the oven to decrease the fanning effect on these areas by outside air currents. l

2. A glass annealing oven, including side Walls and a ceiling, and insulation covering only the upper portions of the side walls and the opposite sides of the cealing, while the center of said ceiling is left uncovered.

3. A glass'annealing oven, insulation covering the upper corners only thereof, side walls having necessary openings therein, and insulated means for preventing unequal heat losses incurred by said openings.

4. An annealing oven, insulation covering the upper corners only thereof, and stopples of insulation for plugging up the necessary openings in the side walls of the oven.

5. An insulated annealing oven, consisting of a plurality of conveying rolls for supporting and advancing a sheet of glass longitudinally through the leer, and means above 'and below the sheet for controlling the direetion and intensity of the heated air cur'- rents above and below the sheet and throughout the length of the oven.

6. An annealing oven, a plurality of conveying rolls positioned therein for advancing a sheet of glass longitudinally therethrough, and insulation `of varying thicknesses positioned upon the upper corners only of said oven in order to create a more uniform temperature condition within the oven transversely thereof.

7. A glass annealing oven including side walls and a ceiling, insulation covering the opposite side portions of said ceiling while the median portion thereof is left uncovered.

8. A glass annealing oven including side walls and a ceiling, insulation covering the opposite side portions of said ceiling While the median portion thereof is left uncovered, said insulation gradually decreasing from one end of the leer to the other.

9. A glass annealing oven consisting of a plurality of conveying rolls for supporting and advancing the sheet of glass longitudinally through the oven, pivotally mounted means beneath the sheet for controlling the direction and intensity of the heated air currents beneath the sheet and throughout the length of the oven. 1

10. A glass annealing oven including side walls and a ceiling, and insulation arranged upon the ceiling, the insulating effect of said insulation varying transversely of said ceilinv'.

t1:1. A glass annealing oven including side walls and a ceiling, a layer of insulation covering the ceiling adjacent the intake end of the oven, and insulation covering the op osite side 'ortions only of said ceiling orwardly of) and adjacent the first mentioned insulation.

12. A glass annealing oven including side walls and a ceiling, a layer of insulation covering the ceiling adjacent the intake end of the oven, insulation covering the opposite side portions only of said ceiling forwardly of and adjacent the first mentioned insulation, and further insulation disposed upon said first mentioned insulation and covering the opposite side portions only of said ceiling.

13. A glass annealing oven including side walls and a ceiling, a layer of insulation covering the ceiling adjacent the intake end of the oven, insulation covering the opposite side portions only of said ceiling forwardly of and adjacent the lirst mentioned insulation, and further insulation disposed upon said iirst mentioned insulation and covering the opposite side portions only of said ceiling, said last mentioned insulation also projecting downwardly and covering the upper i portions only of the side walls.

14. An insulated annealing oven, means for supporting and advancin a sheet of glass horizontally therethroug and pivotally mounted means above and below the sheet for controlling the direction and intensity ofthe heated air currents above and below the sheet and throughout the length of the oven.

15. A glass annealing oven, including means for supporting and advancing a sheet of glass horizontally therethrough, and means for dividing the interior of the oven transversely into two compartments, and for controlling the direction and intensity of the heated air currents beneath the sheet and throughout the length of the oven, the compartment adjacent the entrance end of the oven being relatively shorter than the compartment adjacent the outlet end thereof.

16. A glass annealing oven, including means for supporting and advancing a sheet of glass horizontally therethrough, and pivotally mounted means disposed above and beneath the sheet for dividing the oven transversely into two compartments, and for controlling the direction and intensit of the heated air currents beneath the s eet and throughout the length of the oven, the cornpartment adjacent the entrance end of the leer being relatively shorter than the compartment adjacent the outlet end thereof.

17. A lglass annealing oven, including means for supporting and of glass horizontally therethrough, and means for dividing the interior of the oven transversely into two compartments comprising a damper disposed above the sheet, and a plurality of 'dampers disposed beneath the sheet and arranged side by side transversely of said oven.

18. A glass annealing oven, including means for supporting and advancing a sheet of glass horizontally therethrough, a plurality of dampers arranged side by side and extending transvexsely of the oven beneath the sheet and adjacent the entrance end thereof, and a plurality of dalnpers positioned side by side and extending transversel of the oven above the sheet and adjacent t e outlet end thereof.

19. A glass annealin oven, including means for supporting an advancing a sheet of glass horizontally therethrough, a damper disposed above the sheet and extending transversely of the oven, a plurality of dampers disposed -beneath the sheet and arranged side by side transversely of said oven, and a plurality of dampers positioned side b v side and extending transversely of the oven above the sheet forwardly of the last mentioneddampers.

Signed at Toledo, in the county of Lucas, and State of Ohio, this 8th day of December,

1925. ENOCH T. FERNGREN.

advancing a sheet

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