US1846566A - Annealing glassware - Google Patents

Description

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ANNEALING GLASSWARE Original Filed June 1, 1925 8 Sheets-Sheet 8 [270922 for Vzggj/Mviizoila nd AH zo rne gs Patented Feb. 23, 1932 VERGIL MULHOLLAND, OE WEST HARTFORD, CONNECTICUT, ASSIGNOR TO HARTFORD- EMPIRE COMPANY, or

HARTFORD, CONNECTICUT, A CORPORATION OF DELAWARE ANNEALING GLASSWABE Original application filed October 3,

1925, serial No. 62,237, which is a division of Serial No. 33,977, filed June 1, 1925. Patent No. 1,566,481. Divided. and this application filed May 3, 1929. Serial No. 360,113.

This invention relates to lehrs for anneal ing glassware, and it has particular relation to lehrs' of the type embodying a tunnel which has heating and cooling lines associated therewith and through which the ware is transported, the ware being subjected therein to varying temperature environments. The inventions set forth herein also are set forth in my copending application, Serial No. 62,- 237, filed October 13, 1925 of which this case is adivision. They likewise are set forth but not claimed in my prior Patent No. 1,560,481, granted November 3, 1925 of which the aforesaid copending application is a division, and in my prior Patent No. 1,571,137, granted January 26, 1926, reissued as Patent No. 17,263, granted April 9, 1929, of which this application is a continuation in part.

As is the case in my aforesaid Patent No. 1,571,137 and the reissue thereof, a general object of the present invention is to provide a lehr and a method of annealing glassware by the employment of which ideal temperature conditions for the annealing of the glassware are obtained. Such conditions are set out in detail in my prior patent as follows:

ll all portions of a glass article, which are being annealed, are brought to a uniiorm annealing temperature, and are held at this temperature a suliicient time to permit the release of strains, and it the suhsequent cooling be kept uniform to all portions of the article, can he cooled and. annealed per fectly, which result is not possible in the usual commercial lehr. This is an ideal condition tor annealing and permits the article to he annealed and 090 c i minimum time, as lor instance, with certain kinds of ware, less than one hour compared with two and one-half to live h "'"s in h ol lehr, The nearer such i preached in a tun and better "will be 'lhe matter claii I which as already stated i claimed in my several prior an and in my copending application, is a re c method of annealing, The object ofthis method is to insure that the atoresaid ideal temperature conditions will he obtained by causing the plication,

temperature of the gases of combustion employed in heating the lehr to be lowered to approximately the temperature at which it is desired to hold the ware,prior to bringing them into heat transferring relation with the ware.

More specifically, it is an object of the present invention to provide a novel method of annealing glassware in a tunnel lehr, whereinthe hot gases of combustion to be employed for heating the latter are cooled to a predetermined temperature prior to bringing them into heat transferring relation with the ware, and thereafter a temperature gradient is maintained in the gases throughout the annealing range, corresponding to that gradient desired in the ware. By the accomplishment of this object, the release of strains from the ware is insured and the annealing thereof may be accomplished most efficiently in-the minimum or time.

Another object of the present invention is to provide a lehr of the character described, which shall be of relatively light and inexpensive structure, which may be quickly and easily assembled from a plurality of similar metallic sections, and in which the temperature in the tunnel may be easily and accurately controlled and maintained substantially uniform, so far as the environment of the ware is concerned, throughout any transverse section or zone of the tunnel.

Another object of the invention is to provide a lehr in which the heating and cooling media, flowing in their respective fines, shall be drawn. through the lines by suction and. shall thus be prevented from obtaining access to the tunnel through leaks or crevices that may exist or develop between the dues and the tunnel, which leakage may not only disturh the temperature therein loy establishing hot or cold spots or zones, the location oi which is dificult to determine and which interteres materially with the proper annealing of the ware, but would have a tendency to cause a combustion deposit on the ware. A, construction characterized by the foregoing features is especially well adapted for the practice of the novel method claimed herein,

In the accompanying drawings,

Figure 1 is a diagrammatic vertical longitudinual sectional View of a lehr constructed according to the invention;

Fig. 2 is an enlarged view of the forward or receiving end of the lehr, partly in vertical longitudinal section and partly in side elevation;

Fig. 3 is a similar view of an intermediate portion of the lehr, illustrating the dampercontrolled openings that regulate the temperature in the heating and cooling flues, and also the anti-friction support for the tunnel;

Fig. 4 is a vertical longitudinal sectional view of another intermediate portion of the lehr, illustrating more in detail the sectional construction of the tunnel;

Fig. 5 is a vertical longitudinal sectional view through the rear or exit end of the tun nel, illustrating the draft-producing device and the damper mechanism for controlling the drafts produced thereby;

Fig. 6 is a side elevational View, with parts broken away, of the-ware-sorting table and the conveyor-driving mechanism;

Fig. 7 is a horizontal sectional view taken on line 7-7 of Fig. 2, and illustrating the internal construction of the fire box;

Fig. 8 is a vertical transverse sectional View taken on line 88 of Fig. 2, and illustrating the cross-sectional arrangement of the tunnel and fire box;

Fig. 9 is a vertical transverse sectional view taken on line 99 of Fig. 4, and illustrating the cross-sectional construction of the damper-controlled openings in the heating and cooling flues;

Fig. 10 is a View similar to Fig. 9 taken on the line 1010 of Fig. 5, and illustrating the flues which establish communication between the heating flues and the draft-producing device;

Fig. 11 is a vertical transverse sectional view taken on line 1111 of Fig. 6, and illustrating the construction of the mechanism for taking up slack in the endless conveyor belt;

Fig. 12 is a fragmentary horizontal sectional view through one of the expansion joints in the outer casing of the tunnel, and

Fig. 13 is a fragmentary horizontal sectional view through one of the joints between the side walls of the tunnel.

The present invention is an improvement upon the lehr disclosed in my above-mentioned prior Patents 1,571,137 and reissue No. 17,263 and, as diagrammatically illustrated in Fig. 1, briefly comprises a sectional tunnel A; a fire box B located beneath the forward or ware-receiving end of the tunnel; a plurality of heating flues C, communicating with the fire box and extending longitudinally beneath the tunnel; a plurality of cooling flues D, extending longitudinally above the tunnel; a draft-producing device E, specifically a suction fan, communicating with both the heating flues and the cooling flues;

a ware-sorting table F, located at the exit end of the tunnel; an endless conveyor G, the ware-bearing strand of which traverses the tunnel and the sorting table F, and the idle strand of which returns to the entrance end of the tunnel beneath the lehr; and a conveyor-driving mechanism H.

The several sections of the tunnel are rigidly secured together in end-to-end relation and are supported by suitable framework which includes a pair of longitudinally extending channel members 1 and transversely extending channel members 2 which are, in turn, supported by vertically adjustable pedestals 3. The tunnel is slightly inclined downward from the hot or receiving end to the cool or delivery end to cause a tendency for air to flow through the tunnel, in a direction opposite to that of the movement of the ware. This flow of air through the tunnel is preferably barely suificient to prevent an inflow of cold air at the hot end of the tunnel without necessarily exerting a material cooling influence upon the ware.

Each of the sections of the tunnel is preferably constructed of cast iron and comprises a bottom 4, side walls 5, and a top 6. The bottoms 4 of these sections are of shell-like structure, being formed with a plurality of parallel longitudinally extending ports 7 which, when the sections are arranged in end-to-end relation, constitute the heating flues C. The forward edges of the partitions between the ducts 7 are cut away, as indicated at 711. to insure an equal draft in all of the flues C.

The forward or entrance end of the bottom 4 of the first section of the tunnel is rigidly bolted, as indicated at 8, Fig. 2, to the rear end of a box 9 which, in'turn, is rigidly bolted, as indicated at 10, to the channels 1 of the supporting frame of the lehr and which constitutes the forward end of the heating flues. The forward end of the bottom 4 of each of the succeeding sections of the tunnel is bolted to the rear end of the bottom of the preceding section, as indicated at 11, Fig. 2. The rear end of each of the bottoms 4 is supported by rollers 12 which ride on rails 13 carried by the channels 1.

The rear end of the box 9 and the rear ends of each of the bottoms 4 are provided with seats 14 for telescopic engagement with reduced flanges 15 provided on the forward ends of each of the bottom members 4. The joints thus formed between the several bottom members are sealed with a suitable refractory cement so as to not only prevent the gases traversing the heating flues C from leaking into the tunnel, and causing the hot spots and carbon deposits above referred to, but to also prevent air from the outer atmosphere from leaking into the heating flues and interfering with the control of the temperatures therein.

The side Walls 5 of the tunnel sections are bolted to their respective bottom members t, as indicated at 16, and their forward edges are formed with ofiset flanges 17 (Fig. 13) for overlapping engagement with the rear edges of the corresponding walls of the preceding section.

The top members 6 of all of the sections of the tunnel are supported by the side walls 5 and are provided with a plurality of longitudinally extending corrugations 18 which provide a roof for the tunnel having a relatively large heat radiating surface in comparison with the width of the tunnel. It will be noted, from an inspection of the drawings, that these tops are of two types. For approximately one-third of the length of the tunnel, commencing at its entrance end, the tops 6 are of open construction as illustrated in Fig. 8, but for theremainder of the distance along the tunnel, the tops 6 are also of the shell-like structure best shown in Fig. 9, being formed with a plurality of parallel longitudinally extending ports 19, which,

when the tops are arranged in end-to-end relation, constitute the cooling tlues D.

The lehr is heated by .a burner 20 which projects a flame through an opening 21 into a combustion chamber 22 provided in the fire box B (Fig. 7 The tlame from the burner, upon entering the chamber 22., first impinges. upon an angularly disposed bafie 23 which deflects it in the directions indicated by the arrows in Fig, i. From the chamber 22, the products of? combustion pass forwardly through an opening 24;, provided in a wall 25 and into a mixing chamber 26, where they encounter a battle 2? which deflects them rearwardly and distributes them in a lateral direction throughout the chamher. A port 28 (Figs. 7 and 8) establishes communication between the outer atmosphere and the chamber 26 directly to the rear of the bathe 2'2, and supplies diluting air to the products of combustion as they enter the chamber 26. The amount of air passing through the port 28 may be controlled by a damper 29 provided on the side of the tire box.

The combustion chamber 22 and the mixing chamber 26 are both provided with inner linings 30 of refractory material and with outer linings 31 of heat-insulating brick, which is surrounded by a powdered-insulat: ing material 32, such as kieselguhr, or the like. This structure is contained within a metallic casing 33., which is mounted upon adiustable legs or pedestals 3d and which constitutes the forward support for the channel members l.

From the chamber 26 the products of combustion pass through spaced openings provided in the front wall thereof, and into a draft-equalizing box 36, thence upwardly intoa draft-regulating box 37, and thence into the box 9 which forms the forward end of the heating fiues C. Pipes 38 are provided for admitting air from the outer atmosphere into the box 36. These pipes are provided with caps 39, having air-inlet openings formed therein, and may be individually exchanged for caps having larger or smaller openings to admit varying quantities of air into the box 36 in order to distribute the draft equally transversely of the tunnel. The openings in these caps-may also be employed to observe the character of the combustion in the fire box. A damper is provided in the box 37 in order to regulate the amount of the draft in the fire box l3 and in the heating fiues C.

Both the heated gases and the cooling air are drawn through their respective Flues C and D at sub-atmospheric pressure by a common draft-producing device E comprising a motor driven suction fan l1 whichis mounted on the top of the tunnel adjacent to the exit end thereof. This fan communicates with a drum 42 which in turn communicates with a pair of vertical lines 43 disposed one on each side of the lehr. These fines coinmunicate at their lower ends with a transverse flue ll located beneath the lehr and which in turn communicates with all of the heating tlues C through a longitudinally extending upwardly inclined flue4i5 (Fig. 5). The flue a5 is provided with a damper d6 which'may be operated to control the draft in the heating lines by means of a rod :7 which is threaded into the hand wheel 48.

The drum T2 of the drattproducing device also communicates with the cooling lines D in the top of the tunnel through the medium of a longitudinally extending. conduit 49 dis posed above the lehr, and which communicates at intervals with all of the cooling-dues D through stacks 50 (lligs. 3 and l). These staclrs are provided with dampers 51 which may be selectively operated to regulate the amount and location that the cooling air is drawn out of the cooling dues. it will be noticed from an inspection or" Fig. 1 that the cooling air is drawn through the dues D in a direction opposite to that of the how of the heating gases in the fines U.

A damper 52 is also provided in the conduit 49, as shown in Fig. 5, and may be operated to control the draft in all the cooling tlues by means of a rod 53 which threaded into a hand wheel 54.

The temperature in the iiues C may be regulated by admitting diluting air from the outer atmosphere into these tlues through a plurality of stacks 55 which are arranged at intervals lengthwiseof these flues Dampers 56 are provided in the stacks 55 to enable the operator to regulate the amount and the location where such diluting air is admitted into the heating tlues, whereby the desired temperature drop or curve in these till ltlll ice flues and in the tunnel may be obtained. The dampers 51 and 56 are provided with operating handles 57 and 58 respectively, having .a short distance adjacent to the exit end of the tunnel where it is desired to hasten the cooling of the ware.

By properly adjusting both the dampers 51 and 56 in the stacks 50 and respectively, the desired temperature gradients may be obtained in the flues C and D, and in the portions of the tunnel adjacent-thereto. That is to say, the character of the temperature curves obtained by plotting temperatures as ordinates against distances along the 'lehr as abscissae, in both the heating fines and in the cooling flues is determined by the number and location of the dampers that are opened to the outside atmosphere, and the degree to which such dampers are opened. For example, the less the amount of cooling air from the outer atmosphere that is permitted to enter the forward or hotter portions of the heating flues C, the greater distance will the heat in these flues'influence the temperatures there.- in; and the less the amount of cooling air that is allowed to escape from the rear or cooler ends of the cooling flues D, the greater distance will the cooling air traverse these flues. It, therefore, follows that byregula'ting the amount that thegases in the heating flues are diluted and cooled by outside air, and by regulating the amount of cooling air escaping through the stacks 50. from the cool-- ing flues D and by also determining the location of the dampers that are adjusted, the resultant temperature gradients of the top and bottom portions of the tunnel may not only be controlled at will, but the point or zone of maximum drop in the temperature curves may be shifted longitudinally of the tunnel.

By thus heating the floor of the tunnel to cause upwardly moving convection currents and by cooling the top of the tunnel to cause downwardly moving convection currents and by independently regulating the degree of heating and cooling, the rate of movement of the convection currents in the tunnel may be controlled at will, thereby rendering 1t possible to obtain a substantially uniform temperature, so far as its effect upon the ware is concerned, in a vertical direction in any transverse section or zone in the tunnel.

Dissipation of heat from the tunnel and the heatingfiues is minimized by surrounding the tunnel with heat-insulating material 61 in the form of powdered kieselguhr or the like. This material is contained within an outer casing comprising the following parts: horizontally extending plates-62, which are supported beneath the tunnel by the channels 1 and 2; angle plates 63, which are secured to the sides of the bottoms 4 and which overhang the rollers 12 (Fig. 9) side plates 64 which are secured at their lower edges to the angle plates 63 and which are maintained in spaced relation with the sides of the tunnel by spacer bolts 65; and top plates 66, which extend horizontally above the tunnel in spaced relation thereto and which are secured at their outer edges to the side plates 64. Expansion joints are provided between the vertical edges of the side plates 64 and each comprises a channel 67 and a spacer 68 which are secured to one of the plates 64 and which slidably retain the overlapping edge of the adjacent side plate (F ig'. 12).

The thickness of the insulation 61 may be reduced toward-the rear end 'of the lehr, as shown in Fig. 4, and may be entirely dispensed with adjacent to the exit end of the tunnel, as shown in Fig. 5.

The sorting table F consists of a plurality of spaced parallel longitudinal bars 69 (Figs. 6 and 11) which are supported at their forward ends by the frame of the lehr, and at their rear ends by a frame 70 of the belt driving mechanism H. Rollers 71 are carried at spaced intervals by the bars 69, and provide a support for the conveyor as it emerges from the tunnel bearing the annealed ware. The table F is of sufiicient length to permit several persons to stand side b side on each side of the table to inspect an .remove the ware from the conveyor G for packing. The conveyor G and the table F are suflicientlynarrow to permit easy access, from either side of the table, to ware located in the central portion of the conveyor.

The conveyor G'comprises an endless belt of flexible open structure, the ware-bearing strand of which lies flat upon the cast iron bottom members 4, which constitue the bottom of the lehr tunnel, and upon the rollers 71 of the receiving table F.

As best shown in Fig. 6, the conveyor, as

it advances over the end of the receiving table F, passes over a roller 72 journaled in the frame 70 and thence forwardly and around a driving drum 73 which is mounted on a shaft 74 journaled in the frame 70. At the point where the belt leaves the drum 73, it passes over and rearwardly around a roller 75 which is journalled at its ends in side blocks 76, mounted in ways 77. The drum 73 and the roller 75 are provided with resilient anti-slipping coverings'78 and 79 respectively, composed vof rubber orthe like, so as to present a tractive surface to the belt and insure a positive driving contact therewith. The roller 75 is maintained in gripping contact with the belt G by jack screws 80 which are threaded in the ways 77 and which bear against the side blocks 76. The drum 73 and the roller 75 are rotated by a sprocket wheel 81 which is driven in any preferred manner. The sprocket wheel 81 is mounted on a shaft 82 which carries a worm 83 meshing with a worm wheel 83a carried by a. shaft 84. A pinion 85 is also keyed to the shaft 84, and meshes with a gear wheel 86 mounted on a shaft 87. A pinion 88 is also keyed to the shaft 87 and meshes with a gear wheel 89 carried by the drum 73. The gear wheel 89 meshes with a gear wheel 90 on the roller75, whereby both the drum and the roller are driven at the same peripheral speed.

The conveyor belt G, after passing around the roller 75, passes forwardly and beneath a roller 91 and thence upwardly and rearwardly over an idler roller 92. The idler roller 92 is mounted on a shaft 93, provided with gear wheels 94 at each end which are mounted on rack bars 94a carried by the bars 69. By rotating the shaft 93 by means of a handle 95, the roller 92 may be shifted longitudinally of the table F to take up any slack in the conveyor. After leaving the roller 92, the belt G passes upwardly and forwardly over a roller 96 carried by the bars 69, and thence forwardly beneath the lehr where it is supported at intervals by rollers 97 which 'are mounted on the pedestal 3. At the forward of the conveyor G is supported between rollers 98 mounted beneath the fire box (Fig. 2). As the belt leaves these rollers, it passes upwardly and parallel to the front end of the fire box and thence over a roller 99 disposed adjacent to the entrance of the tunnel. From the roller 99 the belt passes over the box 9 and beneath a guard plate 100 and into the front end of the lehr tunnel.

The entrance end of the tunnel is provided .with a door- 101 which is mounted in ways 102 for vertical sliding movement. This door may be raised or lowered,'to close the upper portion of the tunnel but permitting sufiicient clearance for ware to pass therebeneath by means of rods 103 which are threaded into hand wheels 104 mounted on a frame 105. When the door has been adjusted to the desired height, it may be clamped in position by screws 106 provided in the ways 102.

The exit end of the tunnel is provided with a door 107 which is hinged at its upper edge to the top 6 of the last section of the tunnel and which is provided with arcuate side flanges 108 to prevent an influx of excess air from the outer atmosphere into the tunnel.

The door may be opened sufficiently to permit ware to pass therebeneath and main- 65 tained at such height by a bar 109 which is supporting the tunnel throughout its entire or receiving end of the lehr, the lower strand adapted to be adjustably secured to a bracket 110 carried by the base of the draft-producing device E.

From the foregoing it will be apparent that I have provided a lehr of very rugged and durable structure and one that may be assembled very quickly and easily from a plurality of similar and interchangeable sections. Also, it will be apparent that by my construction and method of drawing the heating gases and the cooling air through the several lines at subatmospheric pressure, the injurious effects of leakage of these media into the tun nel is reduced to a minimum. Furthermore,

length by anti-friction devices renders it possible to eliminate expansion joints or other joints between the sections of the tunnel through which leaks may exist or may develop, and permits the tunnel to expand lengthwise as a unit on its support.

Uertain structural features herein shown and described are not claimed herein, but are specifically claimed in certain of my copending applications. For example, no claim is made herein to the feature of drawing heated gases through a portion of the fiues beneath the tunnel to heat a portion of the tunnel and causing cold air to flow in the opposite direction through another portion of the same flues to cool the exit end of the tunnel, inasmuch as this matter is claimed in myco-pending application filed August 27, 1925, Serial No. 52,751, now Patent No. 1,588,603, dated June 15, 1926.

It is obvious'that the lehr herein disclosed provides flues for the heated gases which are separated from the tunnel by relatively thin cast iron walls which make for rapid heat exchange between the gases and the glassware in the tunnel, and provides a fire box specifically provided with means to regulate the admission of air to dilute the products of combustion passing therefrom into the flues.

As the glassware is to be passed through the tunnel, preferably in close proximity to the walls of the flue and separated therefrom by a conveyor of flexible open-work structure, which does not hinder materially the rapid transference of heat from the ware to and through the flue wall, it is obvious that this lehr should be operated and the controls so used that the products of combustion from the fire box be sufiiciently diluted with air prior to their admission into the flues that their temperature closely approximates that of the glassware at the soaking period, that is, during the time that permanent strains are being released therefrom. When extremely light weight ware is being annealed, the gases are usually supplied to the flue at a temperature slightly higher than this desired soaking temperature to compensate for the greater cooling during the shaping and transferring operations, while with very heavy ware, the flue gases may be at a slightly lower temperature than the aforesaid soaking temperature. Such a control of the condition of the gas at or near the beginning of the flue permits the relatively high temperature of the gases to be continued a material distance down the lehr, without the introduction of additional heat and without the use of too high temperatures adjacent to the entrance end of the lehr and during the soaking period, such as would be required were it not for the greatly increased total volume of gases per unit of time due to the initial dilution of those gases to bring them down to the annealing temperature, as above described.

The provision of the above-recited elements in my lehr, in lieu of the relatively poor heat conducting flues and conveyors of high heat mass of the prior art, permits the use of larger volumes of gases at lower temperatures to obtain the same temperature in the tunnel; and the provisions made by me for the rapid transference of heat from the tunnel to the flue and vice versa permit accurate and flexible control of the temperature gradients in the flue and hence in the ware in the tunnel. The use of relatively large volumes of gas at low temperatures is also a material factor in the economical use of the lehr, inasmuch as it permits of the use of a relatively small amount of fuel to produce an initially small amount of hot gases which are later diluted.

The various features of the invention herein described as incorporated in a single organized apparatus may be used separately or in other combinations, and various modifications may be made in the arrangement and construction of the parts, and in the method of cooling the article to be annealed. For some uses, as for example, for the handling of only one kind of ware, some of the adjustments and other provisions for handling varied kinds of ware may be dispensed with. Again, by mounting the tunnel on anti-friction devices, the tunnel may be made integral throughout its length. In this and in other ways, the method and apparatus herein described and shown may be modified within the scope of the appended claims.

I claim as my invention:

1. The method of annealing glassware that comprises continuously passing the ware through an elongate tunnel, generating hot gases by combustion, passing said gases adj acent to the ware in the tunnel and in good heat transferring relation therewith, and reducing the temperature of said gases between the point of generation thereof and the point at which they first come into good heat transferringrelation to the ware to first present the gases into such relation at approximately the temperature at which it is desired to hold the ware for the release of permanent strains therefrom.

2. A lehr for annealing glassware, comprising an elongate tunnel, a conveyor of flexible openwork material for moving articles of glassware therethrough, a flue having a common metallic wall with said tunnel, means for supplying heated gases to said flue at a point adjacent to the ware-receiving end of said tunnel, and means adjacent to the inlet end of said flue to dilute said gases with air to bring them to a temperature approximating that at which it is desired to hold the ware for permitting the release of permanent strains.

3. A lehr for annealing glassware comprising a tunnel, a flue extending longitudinally beneath said tunnel, a fire box disposed beneath the receiving end of said tunnel and communicating with said flue, a port for ad mitting air from the outer atmosphere into said fire box to dilute the gases therein, and a plurality of adjustable openings located between said fire box and said flue for admitting regulable quantities of atmospheric air into the passage therebetween to distribute the draft uniformly transversely of said flue.

4. A lehr for annealing glassware comprising a tunnel, a plurality of flues extending longitudinally beneath said tunnel, a fire box disposed beneath the receiving end of said tunnel and communicating with said flues and including a combustion chamber, a mixing chamber and. a draft equalizing chamber, means for admitting diluting air into said mixing chamber, and a plurality of openings arranged at intervals transversely of said equalizing chamber and communicating with the outer atmosphere for admitting regulable quantities of air into said chamber to distribute the draft uniformly transversely of said lines.

5. A lehr for annealing glassware comprising a tunnel, a temperature controllin flue associated therewith, a fire box for supplying hot gases to said flue disposed adjacent to the entrance end of said tunnel, means associated with said fire box for admitting atmospheric air to dilute the gases in said fire box to reduce their temperature substantial- 1y to that desired at the entrance end of said flue, and a plurality of laterally spaced inlet passages for admitting additional atmospheric air to said gases to distribute the draft in said flue laterally thereof.

6. A lehr for annealing glassware comprising a tunnel, a temperature controlling flue associated therewith, a fire box for supplying hot gases to said flue disposed adjacent to the entrance end of said tunnel, a burner for projecting a flame into said fire box, means adjacent to said burner for admitting combustion supporting air to said fire box, means for admitting additional air to said fire box to dilute the products of combustion and reduce their temperature to substantially that desired at the entrance end of said flue, and a plurality of laterally spaced controllable air inlet ports communicating with the passage of the diluted products of combustion at a "point between said fire box and said flue for admitting additional air to control the draft distribution laterally of said flue.

7. The method of annealing glassware which comprises continuously passing the ware through an elongate tunnel, generating hot gases by combustion, passing said gases adjacent to the ware in the tunnel and in good heat transferring relation therewith, reducing the temperature of said gases adjacent the point at which they first come into good heat transferring relation to the ware to first present the gases into such relation at approximately the temperature at which it is desired to hold the ware for the release of permanent strain therefrom, and maintaining a temperature gradient in the gases substantially the same as that desired in the ware throughout the'annealing range.

Signed at Hartford, Conn., this 1st day of May, 1929.

. VERGIL MULHOLLAND.

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