US2330984A - Lehr - Google Patents

Description

Oct 5, 1943- D. G. MERRILL LEHR Filed Feb. 12, 1941 4 Sheets-Sheet 1 N Si N 1 a SSS.

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LEHR

Filed Feb, l2, 1941 i 4 Sheets-Sheet 2 Oct 5, 1943- b. G. MERRILL LEHR Filed Feb. 12, 1941 4 Sheets-Sheet 5 Eig. 5.

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Patented Oct. 5, 1943 UNITED STATES PATENT QFFICE LEBE Donald G. Merrill, West Hartford, Conn., assignor to Hartford-Empire Company, Hartford, Conn., a corporation of Delaware Application February 12, 1941, Serial No. 378,499

11 Claims.

This invention relates to glassware annealing lehrs and more particularly to lehrs of the type in which the tunnel gases are caused to recirculate within the tunnel to assure substantial uniformity in cooling of the ware in each cross section of the tunnel through which the ware passes during its regulated cooling.

The embodiment` of the present invention shown in the attached drawings employs electric heating elements as a means of temperature regulation but certain of the features of the invention are not dependent upon the particular means by which the heat is supplied.

The principal object of the present invention is to provide an improved tunnel lehr of the class above described in which the electric heating elements are so constructedand arranged as to provide the desired recirculation of the tunnel atmosphere in which the hotter gases move from the outer lower corners of the tunnel upwardly along the side walls, thence toward the median plane oi the tunnel, thence downwardly through the ware and an openwork conveyor and thence back to the heated lower corners of the tunnel.

A further object of the invention is to provide a positive means for causing the recirculation of the tunnel atmosphere, such means being lo-V cated in the same or in adjacent sections of the lehr tunnel as those containing the heating elements.

A further object is to provide novel means for introducing into the certain sections of the lehr selected quantities of cooling gases and incorporating these gases in the recirculation of the tunnelgases to the desired extent.

A further object of the invention is to provide an electric lehr having inner walls of low heat mass backed by heavy insulation, whereby a mini' imum` of electric current is'required to bring the lehr to the desired temperature, the lehr being provided with means for introducing cooling gases in controlled quantities from outside the lehr to reduce the temperature of selected sections thereof. Y

A still further object of the invention is to provide a novel means for preheating the return strand of the conveyor by means of gaseswhich have been employed to cool the ware and have thus become preheated, the gases being con'- ducted forwardly from the rearward section of the tunnel to a forward section through insulated., passages to preserve their heat.

' These and other objects will appear from the followingdescription of one embodiment of the invention illustrated in the accompanying drawings in which:

Figs. 1 and 2, respectively, show, in vertical longitudinal central section, the forward land rearward portions of a lehr embodying the present invention;

Fig. 3 is an enlarged view of the forward portion of Fig. 1 including additional details of construction; e

4 is a transverse section on line 4-4 of Fig. 5 is an enlarged view of a portion of a zone C, shown in Fig. 1;

Fig. 6 is an enlarged view of a portion of Fig. 2;

Fig. 7 is a transverse section taken on line 1 1 of Fig. 6;

Fig. 8 is a section taken on line 8-8 of Fig. 3;

Fig. 9 is a section taken on line 9 9 of Fig. 1 modied by the addition of electric heating elements not shown in Fig. 1. The employment oi' such units in the relationships shown in Fig. 9 is Within the contemplation of the present invention.

Referring particularly to Figs. 1 and 2, the embodiment of the invention therein shown comprises an elongate tunnel li formed by bottom, top and side walls of suitable heat-resisting and insulating characteristics. The tunnel is normally open at both ends, but is provided at the hotter or ware receiving end with an adjustable door, such as is commonly employed in lehrs of this general type.

kThe tunnel Il may be considered as divided into a series of zones A, B1, B2, C, D and E. Zone A beginning at the ware entering or forward end of the lehr may be designated as the heating zone in which the ware and the conveyor are brought to a suitable high and uniform temperature for the release of strains in the ware. Zones B1 and B2 may be termed slow cooling zones. These zones may be supplied with heating means to control the rate and uniformity of cooling of the ware as it moves through them. Zones C and D are intermediate cooling zones in which the rate of cooling may be increased over that in the slow cooling zone, and zone E may be considered a rapid cooling zone in which the rate of cooling is substantially increasedas the ware more nearly approaches room temperature.

The ware-bearing strand of an openwork conveyor I2, preferably of spiral woven wire construction, extends through the tunnel, being supported therein on spaced inverted L irons I3 secured to a pair of U beams It carried by pillars i5 arising from the iioor of the tunnel. The conveyor is driven by a suitable driving engine (not shown) at the rear of the lehr to continuously move the ware to be annealed successively through the several zones of the ware tunnel. The return strand of the conveyor passes beneath the ware tunnel on suitable rollers Ida until it arrives beneath zone A at the forward cr ware receiving end of the tunnel. It there enters an enclosed passage 6:forined between the bottom and lower'fffr'ont tunnel walls and walls I6a of refractory and insulation material. The passage encloses rolls I1 and I8 around which the return strand passes and changes its direction just prior to becoming the ware receiving strand. Means Y hereinafter described are provided to preheat the conveyor while it is within the passage l5 and to maintain its preheated condition while it receives the ware and until it enters the tunnel.

The walls of the tunnel throughout sections A, B1, B2, and C are preferably constructed of relatively thin insulating board and are heavily insulated, as for example, by suitable thicknesses of glass wool packed between the board and an outer metallic casing. In other sections, D and E, the insulation is reduced or removed to permit an acceleration of the rates of cooling of the ware.

In section A,-the tunnel is provided with two series of transversely extending electric heating elements I9 and 20 at the bottom and top of the tunnel, respectively. These elements are constructed to provide a greater heating effect at the bottom than at the top oi the tunnel. lThe units I9 and 20 are so constructed as to concentrate the heat at the sides oi the lehr tunnel. The elements may be automatically controlled (by means not shown) from a suitable thermostat indicated at 2| to assure the proper application oi' heat in zone A for all loadings of the lehr. Preferably, the lower elements i9 are covered by alloy sheets lila which prevent any broken y glass from falling upon the elements. These sheets Isa do not extend to the front or side wall of the tunnel and the construction permits some movement of air from the rear portion of the lehrforwardly and upwardly along the side and iront walls of the tunnel.

Sections B1 and IB2 of the tunnel comprise slow cooling sections in which the temperature oi' the glass is permitted to fall at a very slow rate through the so-called critical temperature range. These sections are supplied at the lower corners with longitudinally extending heating elements 22 carried on suitable spools or brackets 23. 'I'hese elements may be formed by bending suitable bendable elongate electric heating elements in a series of hairpin bends o selected length so as to extend varying distances from the lower corners of the lehr toward the central portion thereof.' One such electric heating element is supplied by the General Electric Company, Schenectady, New York, and is known commercially as a Calrod electric heating unit. Preferably, the elements are so formed as to provide a concentration oi' their heating efect ad jacent the lower corners of the lehr. The eect the conveyor and back over the heating elements. The construction of the tunnel in these sections is such thatlthe gases therein are aforded unobstructed passage and are free to recirculate in the described manner. Such recirculation of the tunnel atmosphere tends to maintain great uniformity in the temperature of all portions of the bottles passing through the section. As many sections,'B1 and B2, as desired, may be employed andthe current supplied to the units of each section may be suitably selected to give the proper temperature drop longitudinally of the lehr. Current to the heating elements 22 may be controlled automatically from thermostats (not shown) suitably placed to be responsive `to temperatures in the several seci tions.

Section C of the lehr tunnel is designed to eiect a somewhat increased cooling effect on the were while assuring uniformity of temperature in the ware. In this section, the atmosphere of the tunnel is positively recirculated to assure the desired uniformity. Low capacity heating units 22 similar to those described in connection with sections B1 and i32 may be provided in this section or they may be omitted. A plurality of sections C may be employed, and in some of these, the heating units may be employed and in others may be omitted.

.A fan 2li, below the belt and adjacent the center line of the ware tunnel, is mounted on a vertical shaft 25, extending through the bottom wall of the tunnel. The fan is driven through suitable connections from an electric motor 2B and operates within an enclosing structure designed to aid the desired recirculation of gases in the tunnel. This structure comprises an elongated box 2l providing exhaust passages 28 and 29 for directing air from the fan toward the side walls of the tunnel. 'The box 2l is provided with a top 3@ and a false top 3l between which is formed a passage 32 connecting with an opening 33 in the false top constituting an 'intake passage to the fan. A pipe 36, extending through the bottorn wall of the tunnel and provided with a dampered. opening 35, communicates with the passage 32; and by this means, atmospheric air may be introduced into the tunnel and incorporated in the reclrculating tunnel gases.

The top il of the box is provided with openings 36 through which tunnel atmosphere may be drawn into the passage 32 for recirculation by the fan. Plates 3T and 38 are provided to form lateral extensions of Athe tcp 30. These plates terminate short of the side walls and form, with the tunnel bottom, a passage communicating with the openings 2t and 29 to direct the movement of the gases from the fan toward the side walls. By means of these arrangements, controllable quantities of cool air may be mixed with recirculating gases and the temperatures in the tunnel selectively reduced while maintaining the desired uniformity of temperature-in the cooling ware.

As shown in Fig. 9, and if desired, electrical units 22 may be employed in section C, in which event, the gases from the fan will be blown directly over the heating units to maintain the circulating atmosphere at the desired temperature.

As shown, and if desired, the lehr may include one or more muiiie cooling sections D. 'I'hese sections are constructed in accordance with the disclosure of my copending application Serial No. 283,415, Vfiled July 8, 1939, and their details constitute no part of the present invention. In such sections, I provide, in lieu of the insulation used in more forward portions of the lehr, hollow Walls or nues t@ into which cooling air may be drawnthrough dampered openings 40. "I'his air moves across the bottom and up the sides and is exhausted through dampered stacks 4l at the top of the sectior1 The rapid coc-lng section E is designed to rapidly cool the ware from temperatures in the order of v4x50" F. to handling temperatures. The tunnel walls in this section are substantially un-insulated. Means are provided for blowing and circulating cool air into the rearward portions of the tunnel, for moving the same forwardly, of the tunnel and exhausting'them by means of dampered openings. The construction of this section of the lehr is substantially the same as that illustrated and described in my U. S. Patent No. 2,133,783, with the exception hereinafter noted, and hence need not be described in detail.

At the forward end of section E, I have provided a means for taking from the tunnel the air which has been blown into the tunnel and which has become preheated to a substantial degree, say approximately 400 F., and for using it to preheat the ware conveyor. Instead of exhausting this air to the atmosphere as in the lehr of my Patent No. 2,133,783, I have provided a flue 42 communieating with the dampered openings in baille 43 and provided at its rear end with a fan 44 mounted on a vertical shaft 45 projecting through the top of the lehr and driven by a motor 46. The flue extends forwardly through the top insulation, being so located in that insulation that the temp'erature of the gases moving therethrough is maintained. Adjacent the entrance end of the lehr, the flue is Vdivided into branches 48 and 49 which respectively communicate with down ilues in the side walls 50 and 5l, which in turn comn municate with the passageway I6 through which the return strand of the conveyor passes. The hot gases are supplied to the passageway intermediate of its ends and a portion thereof pass rearwardly counter to the movement of the belt, and is discharged at the rearward opening of the passageway while another portion of the gases moves forwardly and following the upward passage of the belt is discharged through the belt and around the front roll to form a curtain of hot gases immediately in front of the loading platform 41. By this arrangement, the belt is preheated, and its temperature maintained during the period in which the ware is set upon the belt and during which it passes into the heated aty mosphere of the tunnel.

I claim:

1. A glass annealing lehr comprising an elongate tunnel, an openwork ware conveyor passing therethrough, electric heating elements below the conveyor and extending longitudinally of the tunnel adjacent the side walls in the same chamber with the conveyor. A

2. A glassware annealing lehr comprising an elongate tunnel having a heating section and a cooling section, an openwork conveyor passing through the tunnel, electric heating elements in the heating section below and in the same charnber with the conveyor and constructed and arranged todeliver heat prinipally adjacent the lower corners of the tunnel to create a thermal recirculation of tunnel gases upwardly along the side walls, thence toward the longitudinally median plane of the tunnel, thence downwardly through the conveyor.

3. A glassware annealing lehr comprising an elongate'tunnel, an openwork conveyor passing through the tunnel, electric heating elements in the tunnel below the conveyor constructed and electric heating elements in the cooling section below the belt constructed and arranged to deliver heat principally adjacent the lower corners of the tunnel to create a thermal recirculation of tunnel gases upwardly along the side walls, thence toward the longitudinally median plane of the tunnel, thence downwardly through the conveyor, and means for introducing into the tunnel and mixing with the recirculating tunnel gases regulated quantities of cooling gases.

5. An electrically heated glassware annealing lehr comprising a tunnel, an 4openwork ware conveyor passing through the tunnel, electric heating meansin saidrtunnel below the conveyor and adjacent the sides of the tunnel, a fan, belowgthe conveyor and adjacent the median plane gf the tunnel mounted and arranged to draw gases downwardly through the conveyor and todise charge them laterally below the conveyor and thence upwardly along the side walls. Y,

6. Ainv electrically heated glassware rvannealing lehr comprising a tunnel having a heating lsec tion, a slow cooling section and a further cqpling section in which'the' rate of cooling is higher than that in said slow cooling section, an open. work ware conveyor passing throughthe tunnel,

electric heating means in the slow cooling section below the conveyor and adjacent Vthe sides of the tunnel, other electric heating means in said flurther cooling section below thel conveyor andati,` jacent the sides of the tunnel, a fan below the conveyor and adjacent the median plane of the tunnel mounted and arranged to draw gases downwardly through the conveyor and" to dis` charge4 them laterally below the conveyor and over the second-named electric heating means and thence upwardly along the side walls.

7. An electrically heated glassware annealing` lehr of the recirculation type comprising a tunnel having a heating section, a slow cooling section and a rapid cooling section, an openwork Ware' walls, and means for supplying controllable amounts of air to the fan from without the tunnel.

8. A glassware annealing lehr comprising an elongate tunnel having a heating section a d a cooling section formed by insulating walls, a ware conveyor having its ware bearing strand entering the tunnel at the heating section, an enclosed passage below and in advance of the heating section for the return strand of the conveyor, a. ilue within the tunnel walls communicating with said passage and means for drawing Vpreheated gases from the cooling section of the tunnel into said flue and delivering them into said passage to preheat the conveyor.

' 9. A glassware lehr comprising insulating walls v forming an elongate tunnel, an openwork conveyor having its ware bearing strand in the tunnel, an open-ended passage outside of the tunnel through which the return strand o1' the conveyor passes, electric heating elements in the forward portion of the tunnel, means for caus- V ing cooling gases to circulate in the rear portion of the tunnel to cool the glassware therein, means intermediate the ends of the tunnel for removing they gases which have become heated through cooling the ware in said rear portion of the tunnel and for delivering them without substantial heat loss to preheat the conveyor.

l0. A glassware annealing lehr comprising a ware tunnel, means for heating the forward end Y of the tunnel, means for introducing cooling gases into the rear portion of said tunnel and causing them to move forward and about the* .ware. an openwork conveyor having its ware bearing strand within the tunnel and its return strand below the tunnel, an open-ended passage without substantial heat loss to the passage intermediate its ends whereby the heated gases move toward both ends of the passage to preheat the conveyor and to provide a curtain of heated gases adjacent the ware-entering end of the tunnel. v

11. A glassware annealing lehr comprising an elongate tunnel having a plurality of adjacent ware cooling sections, an openwork ware conveyor having its ware bearing strand passing through said tunnel, electric heating means in one of said sections constructed and arrangedlto deliver heat principally adjacent the lower side walls of the tunnel to create a convection recirculation of the tunnel gases upwardly along the side walls and downwardly through the ware and conveyor adjacent the longitudinal median plane of the tunnel, and means in another and adjacent section for introducing gases into the tunnel and for positively recirculating the same, said means including a fan mounted in the tunnel below the conveyor and adjacent the median plane of the tunnel, intake passages communicating with upper portions of the tunnel and exhaust passages leading from the fan to the side Walls of the tunnel.

DONALD G. MERRILL.

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