US1572580A

US1572580A - Method and apparatus for casting plate glass

Info

Publication number: US1572580A
Application number: US525327A
Authority: US
Inventors: Frank E Troutman; Charles H Christie
Original assignee: Individual
Current assignee: Individual
Priority date: 1921-12-28
Filing date: 1921-12-28
Publication date: 1926-02-09
Anticipated expiration: 1943-02-09

Description

Feb. 9 1926.

F. E. TRQUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Filed Dec. 28 1921 8 s s t 1 WP UE m TUE F. E. TROUTMAN ET AL,

METHOD AND APPARATUS FOR CASTING PLATE GLASS Feb. 9 1926. 1,572,580

F. E. TROUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Filed Dec. 28. 1921 8 t -sheet 4.

Feb. 9 1926. 1,572,580

F. E. TROUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Dec. 8 sheets-sheet 5 FIG. 8 E:

IN ENTORS FT y I M W F. E. TROUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Feb. 9 1926. I

Filed Decv 28. 1921 8 S ee s-Sheet mv NTORS FIG. 14

Feb. 9 1926.

F. E. TROUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Filed Dec. 28. 1921 8 s t sh j, '7

FIG; 18

FIG.1 9

//h r L Feb, 9 ,1926. 7 1,572,580

F. E. TROUTMAN ET AL METHOD AND APPARATUS FOR CASTING PLATE GLASS Filed Dec. 28. 19 21 8 s t sh t a FIG. 22

FIG. 20

FIG. 2|

of the Patented Feb. 9, 1926.

UNITED STATES 1,572,580 PATENT OFFICE.

FRANK E. TROUTMAN AND CHARLES E. CHRISTIE, OF BUTLER, PENNSYLVANIA.

METHOD AND APPARATUS FOR CASTING PLATE GLASS.

Application filed December 28, 1921. Serial No. 525,327.

tus for casting plate glass from a tank fur-' nace which are described and claimed in our copending applications for Letters Patent filed May 7, 1919, Serial No. 295,485 and- Serial No. 295,486, now issued at Patents- No. 1,535,061 and N 0. 1,535,062, respectively.

In our said patents we have pointed out the fact that glass melted in tank furnaces has not been considered suitable for the manufacture of plate glass because of the high temperature at which the glass is delivered if poured from an ordinary tank furnace, and on account of the agitation of the glass which takes place if the glass is ladled from the tank and poured from the ladle on the casting table, so that the art of casting highgrade plate glass has been confined in practice to the use of pot furnaces, the glass being melted inpots, and the entire furnace being cooled after the glass is melted to reduce the temperature of the glass to a suitable working temperature. Since this process is slow and expensive, and since the operation of the pot furnaces is often inefficient, we desire to provide means for obtaining by the use of a tank furnace the same high quality of plate glass that is produced in pot furnace practice.

Qur casting system as set forth in the above mentioned patents involves the use of a long extension or forehearth from the tank furnace, through which glass flows from said tank furnace, the purpose of this extension being to reduce the temperature lass from the furnace temperature to a suitable working temperature. This forehearth or extension terminates in a dis charging well controlled by a plug or plunger which operates to close the discharge opening in the bottom of-the well,

and also serves to give an impulse to the discharging glass, The glass issues from the well in a-thick, cylindrical column, and

is received upon a, casting table which is passed beneath the opening so as to receive the column of glass in a long mass of approximately uniform thickness, ready to be rolled out into a sheet by means of the usual roller.

Our present invention relates particularly to the handling of the glass at the discharging well. Instead of employing the plug or plun r as a simple valve to open and close the ficharge opening we utilize it as an accelerating member to control the flow of glass by giving it an impulse throu h the opening during the discharging erio We also provide Improved means For clearing away the aftermath or last portions of glass whichgdribble from the openingafter the plunger seats and closes the discharge openmg, and also im roved means for closing the o ening in a dition to the plunger, this additional closure means consisting of a cup-like device applied to the opening from the outside.

In discharging a large quantity of glass upon a casting table no great difficulty is experienced in stopping the flow, but it is a difiicult matter to start the flow properly so as to cause the leading end of the stream to reach the table in proper condition as to its temperature and sha e. If the leading end of the glass dribbles,1t causes a defect which is likely to remain in the glass, forming an imperfection in the finished plate, and if bubbles are entrapped by the leading end of the stream they also remain as defects in the plate. Our present invention. therefore, is largely concerned with the handling of the glass at the beginning of the discharging op eration. It also includes improved means for keeping the column of glass uniform in section as it is received upon the casting table, this latter improvement resulting from the movement of the plunger mentioned above. We may also give the casting table a novel movement, whereby the table is not only moved horizontally past the discharge opening, but may be raised toward the discharge opening as the glass is discharged, so as to prevent the thinning of the stream of glass which tends to take place during the discharging operation. Both the plunger and table-raising operations may be employed in combination.

In the drawing, Fig. 1 is a longitudinal vertical sectional View taken through a complete casting plant constructed in accordance with our invention; Fig. 2 is a horizontal sectional view through the apparatus of Fig. 1, the section being taken substantially on the line 22, Fig. 1; Fig. 3 is a longitudinal. vertical sectional view taken centrally through the plunger and the discharging well; Fig. 4 is a vertical sectional view similar to Fig. 3 showing the parts at a 'difi'erent point in the cycle of operations; Fig. 5 is a fragmentary vertical sectional view showing the outlet of a discharging well, and the construction of the outside closure cup; Figs. 6 to 11, inclusive, are a series of vertical sectional views through the well showing somewhat diagrammatically the successive steps in the discharging op eration; Fig. 12is a vertical section through the well showing a modified form of plunger which may be employed; Fig. 13 is another vertical sectional view similar to Fig. 12 showing another modified form of plunger; Fig. 14 is a plan View showing one form of connection for operating the closure cup; Figs. 15, 16 and 17 are a series of diagrammatic vertical sectional views showing the manner in which the shape of the discharged glass may be modified by changing the speed at which the table travels; Fig. 18 is a side view. mainly in vertical section. showing a modified form of closure device for the discharge well; Fig. 19 is an enlarged vertical sectional view through "the well of Fig. 18 showing the details of construction of the v closure mechanism; and Figs. 20, 21 and 22 are a series of diagrammatic vertical sectional views showing the manner in which the closure device of Figs. 18 and 19 may be operated to deposit glass upon the casting table.

In the drawing, the numeral 2 indicates a tank furnace of conventional construction, such as is commonly used in the glass art. having the usual floaters 3, skimmer 4t and chimney 5. The finished glass from the tank 2 issues through a discharge opening 6 controlled by a gate valve 7 and enters a runway 9 in the nature of an elongated forehearth, which is constructed of retractory blocks fitted together and supported on structural steelwork 10 resting on brick piers 11. A chimney 12 may be provided in the runway 9, and openings 13 may be formed in the sides of the runway for the admission of cooling air or fuel burners to regulate the temperature of the glass flowing through the runway. The molten glass leaves the tank furnace at a high temperature and must be cooled somewhat before being worked, this cooling being accomplished either by natural radiation as the glass passes through the runway 9, or by ventilation through the openings 13. Cer-- tain of the openings 13 may also receive gas burners for reheating the glass if at any time it becomes too cool. Burners or air openings 13 may be placed at suitable points over the discharge chamber 15.

Near the delivery end of the runway 9 is a gate valve 14 by means of which the flow of glass from the runway may be stopped when desired. Beyond the gate valve 14: is a discharge chamber 15 which, as shown in Figs. 1 and 2, is materially larger than the runway 9. both as to its depth and as to its width. This discharge chamber. may be lectangular or circular in form and may be built up, as shown, of double walls of fireclay bricks. The chamber 15 is provided with a downwardly and inwardly tapering conical well 16 which is below the level of the runway 9 and forms a seat for a discharge bushing-17. A plunger 18 extends through the cover 19 of the discharge chamber 15, and is suspended from above by any suitable means, not shown. Any suitable means, not shown, may also be provided for reciprocating the plunger 18 at suitable intervals.

The lower end of the plunger 18 seatsin the bushing 17, and the lower end of the plunger may be either cut off straight, as shown in Fig. 1, or may be curved as shown in Figs. 3, 4 and 6 to 11, or may have any other suitable shape.

In addition to the plunger 18. we provide additional means for closing the discharge opening through the bushing 17, such additional means consisting of a closure cup 20 which is applied to and removed from the discharge opening by mechanism which is described below. In some cases the closure cup 20 may be used as the sole means for closing the discharge opening, the plunger 18 being omitted. I

' The glass flowing from the discharge opening is received upon a casting table 21 having the usual roller 22 and mounted on wheels 23 which run on tracks 24, which tracks may be inclined as shown on Fig. 11 for the purpose'of raising the table 21 toward the discharge opening during the operation. The table 21 may be provided with the usual motor 25 and gearing 26 for moving the table past the discharge opening at controllable speed.

The plunger 18, as shownin Fig. 3, may be made hollow and may contain'cooling arrangements which, as shown, consist of a pipe 30 closed at its lower end by a leap 31 and a smaller pipe 32 extending nearly to the bottom of the pipe 31. Water, air or other cooling fluid, may be introduced through the )ipe 32, and removed through the pipe 30 or keeping the plunger at the desired temperature.

The construction and operation of the outside closure cup 20 are best shown in Figs.

3 to 5 and 1%. This cup may be air-cooled or water-cooled, and for this purpose is made hollow and provided with inlet and outlet pipes 35 having flexible hose connections 36. The top of the cup 20 is dished as shown at 37 in order to impart the desired curvature to the leading end of each charge of glass, and the upper edge of the cup around the dished portions 37 are made flat, as shown at 38, in order to seat closely against a flange 39 which is formed around the discharge opening in the bushing 17 The cup 20 is supported from beneath on a swinging arm 40, the outer end of which extends through slots formed in a sleeve 42 I which is bolted to an anular flange 43 formed on the underside of the cup 20. A pin 44 extends through the sleeve 42 beneath the arm and assists in holding the cup in place. A spring 45 is received within the annular flange 43 and is compressed between the bottom of the cup 20 and a small flat plate 46 having a spherical boss 47 which rests in a depression formed in the upper edge of the supporting arm 40. By this arrangement the cup 20 may have a certain amount of independent rocking movement on the arm 40 to enable it to seat closely against the flange 39 and the spring 45 cushions the shock when the cup comes into contact with-this fia e.

When the cup 20 is withdrawn from t e discharge opening itis first swung downward and then swung to one side in order to completely clear the discharge opening and permit the glass to flow down upon the table 21 without striking the cup. For this purpose, the arm 40 is carried by a sleeve 50 which loosely surrounds a rod 51, the upper end of which is pivotally attached, at 52 to a supporting bracket 53 secured to the underside of the discharge chamber 15 or to any other convenient stationary support.-

The lower end of the rod 51 is-pivoted at 5* to one end of a link 55, the other end of which is pivoted at 56 to a vertical lever -57,' the upper end of which is pivoted at 58 to a stationary bracket 59. The ,i-lever 57 has a slot 60 which receives a in 61 carried by the piston rod 62 of a dou le-acting air cylinder 63. When air is admitted-to the cylinder 63 to movethe piston rod 62 to the right, as shown in Figs. 2 and 3, the lever 57 is also moved to the right and acts through the link 55 to rock the rod 51 around its pivot 52, thereby swinging down the arm 40 and with it the cup 20.

In order to .swingthe arm 40 to one side after it has descended in the manner just de scribed, the sleeve 50 is provided with an arm 65, best shown in Figs. 3 and 14, and this arm is; connected at 66 to one end of a link 67, the other end of which'is connected by means of aball and socket joint 68 to one acting air cylinder 72.

When air is admittedto the upper end of the cylinder 72, as shown in Fig. 14, the piston rod 71 is drawn into the cylinder, thereby exerted a pull through the link 67 upon the arm which swings the arm 40, carrying with it the cup 20 from the full line position to the dotted line position as shown in this figure.

Fig. 14 also shows, by way of example, one manner in which the

cylinders

63 and 72 may be operated in the-proper manner to move the cup 20 first downward and then laterally, and later to return the cup to its position at the discharge opening. Air under pressure enters at the right of Fig. 14 through a pipe 75 controlled by a manually-operated three-way valve 76 and having a branch pipe 77 controlled by an automatic threeway valve 78. Assuming that the cup'20 is in position to close the discharge opening, and

from its neutral position to the position 7 9, air will pass from the pipe 75 through the valve 76 and through a pipe 80 to the cylinder 63, forcing the piston to the right, and thereby moving the piston rod 62 to the right andlowering the rod 40 and the cup 20 through the connections described above. The piston rod 62 carries a trip 81 which works between the operating

arms

82 and 83 of the automatic three-way valve 78. As the piston rod 62 nears the end of its stroke to the right the trip 81 engages the arm 83 and moves it to the dotted line position shown in Fig. 14, which operates the valve 78 to admit air from the branch pipe 77 to the pipe 84 leading to the upper end of the cylinder 72, which forces the piston of the that the handle 79 of the valve 76 is moved cylinder 7 2 downward, as shown in Fig. 14,

inder 63, forcing the pistonof this cylinder back to the left and raising the cup toward the level of the glass discharge opening. During this movement the trip 81 engages the arm 82 of the valve 78 and rocks the valve to admit air through a-pipe 86 to the lower end of the cylinder 72, as shown in Fig. 14:, which actuates the piston of this cylinder and thereby swings the cup through the connections described above to its posi: tion directly beneath the discharge opening. The parts are so proportioned that the cup' arrives at its position beneath the discharge opening before itis completely raised, so that it is accurately seated upon the flange 39 of the bushing 17.

The several stages in which the abovedescribed apparatusis operated are shown in Figs. 6 to 11 of the drawing. Fig. 6 shows the starting position, in which the plungcr'lS is down, with its lower end seated in the discharge opening and thecup 20 is raised to close the discharge opening from beneath. As stated above, the cup 20 may be water-cooled and one operation consists in raisingthe plunger 18 slightly so as to permit a small quantity of glass to flow down around the edge of the plunger and cover the upper-surface of the cold cup. A skin of chilled glass is thus formed on the surface of the cup, and the plunger 18 is then raised further to the position shown in Fig.

7. the cup 20 remaining in position to close the discharge opening. After the plunger is fully raised the cup 20 is lowered, as shown in Fig. 8, and the skin of chilled glass which has been formed by contact with the cup 20 remains at the discharge orifice and begins to sag down, presenting the rounded bag-like appearance shown at A on Fig. 8. \Vhen the cup 20 swings down it is immediately swung to one side, leaving the discharge opening entirely unobstructed, as shown in Fig. 9. The glass continues to descend under the force of gravity due to the head of glass in the discharge chamber 15, and falls upon the table 21, as shown at B, Figs. 4 and 9.

As soon as the leading end of the column of glass reaches the table 21 the table begins to advance past the discharge opening. Since the tracks 21 on which the table 21 travels are inclined upwardly in the direction of movement of the table, the surface of the table not only advances past the discharge opening but rises toward it. The purpose of this movement is to prevent the thinning of the column of glass which otherwise would necessarily result as the head of glass in the discharge chamber lowers, and the inclination of the tracks 24 is such as to compensate as closely as possible for this decrease in the size of the column, so that the mass of glass received on the table is of substantially uniform diameter from .end to end, as shown at C in Fig. 11.

in order to compensate further for the tendency of the glass column to decrease in size, the plunger 18 is caused to. descend as the glass issues, thereby accelerating the dis charge of the. glass. The plunger is shown descending in-Fig. 10, and it will also be observed that in this figure the table 21 has risen appreciably above its starting position shown in Figs. 8 and 9. This downward movement of the plunger takes place near the end of discharge and the flow of glass is cut off by the seating of the lower'end of the plunger in the discharge opening, as shown in Fig. 11. The level of the glass in the discharge chamber preferably does not fall below the lowest glass level in the runway 9.

On aceountof the viscous nature of'the glass the flow cannot be cut off sharply by the plunger, but a tail of glass remains between the discharge opening and the main body of glass on the table 21, as shown at Din Fig. 11. For the purpose of removing this string of glass and cleaning off any glass that may dribble around the end of the plunger just after it seats, we provide a gas burner E which is diagrammatically shown in Fig. 11, and which is manually operated to clean off the lower end of the plunger and the edges of the discharge opening aftereach charge of glass is delivered. \Vhen this cleaning operation is completed the closure cup 20 is returned to its position at the discharge outlet and the apparatus is in the starting position shown in Fig. 6, where it remains until the glass which has been delivered is rolled and the table is ready for another charge.

\Vhen the closure cup'is brought into position under the discharge outlet a small amount of air is entrapped in the space between the cup and the lower end of the plunger. As the plunger rises before the closure cup descends, it may be desirable to provide means for disposing of this small amount of entrapped air so as to prevent it from mingling with the glass and forming a defect in the oured mass. One way of accomplishing this is shown in Fig. 12, where the plunger 18 is provided at its lower end with a small depression communicating with a passage 91 leading to the outer air or to a source of suction. When the initial portion of glass is allowed to flow around the plunger upon the cup 20, the entrapped air passes out through the passage 91.

Fig. 13 shows a modified form of plunger which may be employed when it is desired to increase the accelerating effect of the plunger for special conditions of operation. The plunger 18 in this figure is shown surrounded by an annular auxiliary plunger member 92 which is intended to be mounted separately from the plunger 18 for downward movement when the plunger 18 has nearly completed its downward stroke. The

auxiliary plunger 92 assists the plunger 18 in forcing the glass through the discharge opening.

The above described apparatus operates to deposit the molten glass in front of the roller in a long mass or welt of great uniformity, both as to its shape and as to its temperature, so that the plateof glass formed by rolling out this welt on the casting table is free from bubbles, waves tion, due to changes in the temperature at the discharge well, the movement of the ta ble may be slightly speeded up or checked so as to keep the glass uniform on the table.

The speed of the table mayalso be altered in order to change the shape of the welt of glass, and Figs. to 17 of the drawing show how the shape of the delivered glass may-thus be changed. Fig. 15 shows the manner in which the glass is deposited on the table 21 when the table is moving in the direction of the arrow at a speed equal to, or slower than, the s eed at which the column of glass descen s. The main portion of the delivered glass is shown at 95, while the numeral 96 indicates a protuberance or heel which forms ahead of the descending column of glass. This heel 96 increases in size if the glass descends materially faster than the table takes it away. At the same time, when the table is moved past the discharge opening at a relatively slow rate, the glass spreads laterally to some extent and forms a comparatively wide streak or welt, as shown at 97* inFig. 17

Fig. 16 shows the manner in which the glass is received on the table 21, when the table moves faster than the descending column of glass," and consequently exerts a pull on the glass. Inthis case the heel or prot-uberance 96 is not formed, but the glass descends upon the table in a regular curve,

as shown at 97, Fig. 16. This method of discharging the glass produces a relatively narrow streak or welt, as shown at 98, Fig. 17,. It will be understood that Fig. 17 shows the discharged glass as seen from the left 'of Fig. 15 and also from the left of Fig. 16.

It will thus be evident that both the shape and the quality of the delivered glass may be closely regulated in accordance with the condition of the glass and the size of the plate that is to be formed.

Figs. 18 to 22 show a modified form. of outsideclosure means in the nature of a fluid-cooled knife w ich reciprocates across the bottom of the gl ss out-let, a fluid-cooled ring bein interposed between the knife and the clay ow-bushing. As shown in these figures. the discharge chamber 15 is of the saine general shape 'as in the forms of apparatus first described above, and has a flow bushing 17 beneath which is attached, by means of bolts 100, a flat hollow ring 101 through which water or other cooling fluid may be circulated by means of any ordinary connec tions. Below the cooled ring 101 is a boxlike knife 102, the upper surface of which slides in contact with the flat under-surface of the ring 101. A fluid pressure cylinder 103 is mounted in line with the knife 102 and has its piston rod 104 connected to the knife 102 by means of a coupler 105.

The knife 102 may be mounted in any suitable manner for reciprocation beneath tact with these chilled surfaces.

the glass outlet. For example, it may be mounted as shown in Fig. 19, which shows one member of a pair of stationary guide tracks 106 upon which the knife 102 is supported by means of rollers 107 carried by stirrups 108 which pass beneath the knife 102 and are adjustable by means of screws 109 to bring the knife '102 into close, slidable contact with the under'surface of the ring 101". T

Figs. 18 to 22 show the apparatus just described in operative relation to a castin table 21 running on tracks 24 which are ere shown as horizontal tracks, but which may, if desired, be inclined in the manner shown in Fig, 11. The table 21 may be provided with a shelf 110' to receive the leading end of the stream of glass in the manner described below.

The operation of this form of our apparatus is shown in four successive stages in Figs. 18, 20, 21 and 22.v In Fig, 18 a welt of glass, indicated as above'bv the letter C, has been deposited on the table 21 and the knife 102 has been moved forward by the cylinder 103 to close the glass outlet. While the glass on the table 21 is being rolled, the knife 102 and they cooling ring 101 present chilled surfaces to theglass within the discharge chamber 15 and produce a skin of partially or wholly solidified glass in con- When the next casting operation'is to be performed,

the table 21 is brought into the position shown in Fig. 20 and the cylinder 103 is operated to withdraw the knife'102 away from the glass outlet. As soon'as the knife is withdrawn, the glass. begins to descend 7 under the gravity head of the glass in the chamber 15.

column remains at F and may be withdrawn by means of a hook or other implement, leavin the molten glass free to descend on the taiile, or, as shown in Fig. 20, the leading end of the column, including the nose F with its chilled skin and a portion of the fully molten glass following this nose portion, may be received on the shelf 110 which projects from the forward end of the table The chilled skin of glassaround the lower end of the descending 21. This is shown in dotted lines at G, v

Fig. 20." The table 21 is then moved from left to right, as shown in Fig. 21, leaving the leading portion of the glass upon the shelf 110 and depositing a. clean welt of glass on the table 21" in the manner described above. At the end of the operation, the cylinder 103 is again operated to move the knife 102 across the glass outlet, as shown in Fig. 22, thereby cutting off the last portion Hof the glass which falls upon the table 21 and preferably hangs overthe side of the table, as shown in Fig. 18.

The dribbling of the glass at both ends of the table, as shown in Figs. 18 and 22,

may be employed not only with this particular form of closure means. but also with the other flow-controlling devices described above. This method of operation, whereby both the leading end of the column of glass and the rear end of the column of glass are allowed to fall freely from the table, makes it possible to receive on the table only glass of uniform temperature, shape and quality, since the leading end of the column will carry with it any chilled portions, together with any fragments of clay or .other 1mpurities that may be present, while the tail end of the column, which mav be somewhat chilled by the shears or other means employed for stopping the flow, is likew se dis carded. This method of operation is possible only when, the glass is deposited on the casting table from a glass reservoir having a considerably great capacity compared with the amountpf glass received upon the table at any one operation, and is not possible when the glass is merely poured upon the table from a pot or from a reservoir having the capacity of a single charge plus a comparatively small residue, as in prior glasscasting apparatus.

Asstated above, the speed at which the casting table advances below the glass outlet may be varied to change the shape of the welt of glass. The speed of the table during a given casting operation may either be constant throughout the operation,- or may be increased or decreased, in order to impart a particular shape to the glass as it falls on the table or to compensate for temporary irregularities in the flow of glass from the discharge chamber, so that the shape of the mass of glass received on the casting table may be accurately controlled within narrow limits. Ordinarily it is desired that this mass of glass be uniform in size and shape 7 from end to end, but for particular purposes this shape may be altered by speeding up or retarding the table during a portion of its advance.

The vertical distance between the glass.

discharge outlet and the surface of the casting table is important. This distance should not be less than the diameter of the descending column of glass, and is ordinarily several times that diameter. The maximum vertical distance between the glass discharge and the surface of the casting table should not be greater than ten times the diameter of the glass discharge, Y

WVe are aware that plate glass has been cast by pouring molt-en glass through h spout tarmac in certain. desirable forms of our improved apparatus, we recognize that various changes in the form and construction of parts may be made without' departing from our invention, and We therefore wish. it to be understood that our invention is not limited to the details here shown and described, but may be modified within the scope of the appended claims.

lVe claim as our invention:

1. The method of casting molte'n glass that comprises establishing a body of molten glass above a discharge outlet, and then chilling the glass at the outlet to a. predetermined thickness to cause the glass to is sue slowly initially from the said outlet.

2. The method of casting molten glass that comprises establishing a body of molten glass above a discharge outlet, chilling the glass at the outlet toa predetermined thickness to cause the glass to issue slowly initially from the said outlet, and then to flow freely therefrom, and thereafter applying an accelerating impulse to the glass above the said outlet.

3. The method of casting molten glass that comprises placing the glass in a receptacle having a discharge opening in its bottom, closing the said discharge opening by a closure member applied from within the said receptacle and also by a cooled closure member applied from outside the receptacle, relieving the opening slightly of the said inside closure to permit a portion of the glass to flow in contact with the said outside closure, permitting the glass in contact with the outside closure to chill, removing the said inside closure, and then removing the said outside closure.

4. The method of casting molten glass 105 that comprises placing the glass in a receptacle having a discharge outlet in its bottom, the said outlet being closed by means within the receptacle and also by means outside of the said receptacle, removing the said 110 inside closure means, then removing the said outside closure means to permit the glass to issue from the said outlet, thereafter applying an accelerating impulse to the lass within the said receptacle, receiving the oW- 11 ing glass upon a casting table and rolling the glass on said table into a sheet.

5. The method of casting molten glass that com rises placing the glass in a receptacle having a discharge outlet in its bottom, 1 the said outlet being closed by means within the receptacle and also by means of a cooled closure member outside of the re ceptacle, removing the said inside closure. permitting the glass in contact with the said 125 outside closure member to. chill and form a skin across the said outlet, then removing the said outside closure member, thereby permitting the glass to first issue slowly from the said outlet and then to flow free 1 ly therefrom, and thereafter applying an accelerating impulse to the glass within the receptacle.

6. The method of casting molten glass that comprises placingthe glass in a receptacle having a discharge outlet in its bottom, the said outlet being closed by means within the receptacle and also by means of a cooled closure member outside of the receptacle, removing the said inside closure, permitting the glass in contact with the said outside closure member to chill and form amskin across the said outlet, then removing the said outside closure member, thereby permittin the glass to first issue slowly from the said outlet and then to flow freely therefrom, thereafter applying an accelerating impulse to the glass within the receptacle, then closing the saidv outlet by means of the said inside closure member. V

7. The method of casting molten glass that comprises placing the glass in a receptacle having a discharge outlet in its bottom, the said outlet being, closed by means within the receptacle and also by means of a cooled closure member outside of the receptacle, removing the said inside closure, permitting the glass in contact with the said outside closure member to chill and form a.

skin across the said outlet, then removing the said outside closure member, thereby per mitting the glass to first issue slowly from the said outlet and then to flow freely therefrom, thereafter applying an. accelerating impulse to the glass within the receptacle, then closing the said outlet by means of the said inside closure member, applying a flame to the said outlet to remove the glass depending therefrom, and then replacing the said outside closure member.

8. The method of casting molten glass that comprises placing the glass in a receptacle having a discharge outlet in its bottom, the said outlet being closed by means of a plunger within the said receptacle and also b means of a cooled closure member outside of the said receptacle, raising the said plunger slightly to permit glass to flow down around its end into contact with the said outside closure member, permitting the glass in contact with the said outside closure member to chill and form a skin across the said outlet, raising the said plunger, removing the said outside closure member, thereby permitting the glass to issue slowly from the outlet, and thereafter to flow freely therefrom, lowering the said plunger to apply an accelerating impulse to the flowing glass, and thereafter to close the said opening, applying a flame adjacent to the said opening to remove the glass depending therefrom, and

then replacing the said outside closure member.

9. The method of casting molten glass that comprises placing the glass in a receptacle having a discharge-outlet in its bottom, the said outlet being closed by means of a plunger within the said receptacle, and also by means of a closure member outside of the said receptacle, removing the air entrapped between the said inside and outside closure members, raising the said plunger, and thereafter removing the said outside closure member to permit the glass to flow through the said outlet.

10. The method of casting molten glass that comprises causing the glass to flow in a: streamtrom an outlet upon a casting table, advancing the said table'past the said outlet, and simultaneously raising the said table toward the said outlet.

11. The method of casting molten glass from an outlet and receiving the flowing. glass directly upon a casting tabledisposed at a vertical distance below said outlet at that-comprises flowing the glass in a column least as great as the diameter of the flowstream of glass and not more than ten times as great as the said diameter.

14. The method of casting molten glass that comprises discharging the glass downwardly from an outlet upon a moving casting table in a vertical column that con tracts only slightly in cross-section between said outlet and said table, and restricting the said outlet when the said table passes beyond said outlet, thereby permitting the glass to flow over the rear edge of said table in a contracted stream.

15. Apparatus for casting plate glass chilled glass of predetermined thicknessacross said outlet to cause the molten glass to issue slowly initially from the said outlet and thereafter to flow freely'there'from, and means for applying an accelerating impulse to the glass flowing through the said outlet.

17. Apparatus for casting plate glass comprising a discharge chamber having an outlet in its bottom, and a hollow closure member adapted for chilling the glass disposed outside of the said chamber for clos' ing the said outlet, the surface of the said closure member immediately below the said. outlet being depressed to form a recess communicating with the said outlet.

18. Apparatus for casting plate glass comprising a discharge chamber having an outlet in its bottom, ahollow closure member movable to close the said outlet from beneath, and means for circulating cooling fluid through the said hollow closure member, the upper surface of the said closure member being depressed to form a recess communicating with the said outlet, whereby when the said closuremember is in place to close the said outlet it operates to form a downwardly curved skin of chilled glass across the said outlet.

19. Apparatus for casting plate glass comprising a discharge chamber having a flow-bushing in its bottom, an annular flange formed beneath the said flow-bushing around its outlet, a hollow closure member, a movable support for the said member, means for actuating the said support and for pressing the said closure member resiliently against the said flange, means for permitting the said closure member to rock upon the said support, and means for circulating cooling fluid through the said closure member.

20. Apparatus for casting plate glass comprising a discharge chamber having an outlet, means for closing the said outlet,- means for establishing a skin ofichilled glass of predetermined thickness across the said outlet, and means for thereafter opening the said outlet.

2i. Apparatus for casting plate glass comprising a discharge chamber having an outlet in its bottom, means within the said chamber for closing the said outlet, means outside of the said chamber for also closing the said outlet, and means for removing air entrapped betweenthe said inside and outside closure nicans.

29.. Apparatus for casting plate glass ofthe said chamber for also closing the said outlet, the said plunger being provided with a depression in its lower end for receiving air entrapped between the said plunger and the said outside closure means, and also being provided with a passage communieating with the said recess for removing air therefrom.

23. Apparatus for casting plate glass comprising a discharge chamber having an outlet, a plunger within the said chamber for closing the said outlet, and an auxiliary annular plunger surrounding the said firstnamed plunger, the said auxiliary plunger being independently reciprocable with re spect to said first-named plunger.

24. Apparatus for casting plate glass comprising a discharge chamber having an outlet, a plunger within the said chamber for closing the said outlet, means outside of the said chamber for also closing the said outlet, and an auxiliary annular plunger sur-' rounding the said first-named plunger, the said auxiliary plunger being independently reciprocablewith respect to said first-named plunger.

25. Apparatus for casting plate glass comprising a casting table, means for discharging a column of glass upon the said table, and means for advancing the said table past the said pouring means, and for simul taneously raising the said table toward the said pouring means.

26. Apparatus for casting plate glass comprising a wheeled casting table, means for discharging a column of glass vertically upon the said table, and tracks for support ing the said table, the said tracks being inclinedupwardly in the. direction in which the said table moves while receiving glass from the said discharging means, whereby the said table is simultaneously moved past the said pouring means and raised toward the said pouring means.

27. Apparatus for casting molten glass comprising a receptacle having an opening in its bottom, a casting table adapted to move beneath said opening,'and means for rolling the glass on said table into a sheet, the vertical distance between said outlet and said table being not less than the diameter "of said opening and not greater than ten times the diameter of said opening.

Intestimonywhercof, we, the said FRANK E. 'lnon'ramN and CHAnnns H. Cmus'rie, have hereunto set our hands.

' FRANK E. TROUTMAN.

CHAS, H. CHRISTIE.