US1870262A - Muffle furnace leer - Google Patents

Description

Aug. 9, 1932. w. A. MoRToN MUFFLE FURNACE LEER Filed Feb. 8, 1929 NN. ON.

Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE MUFFLE FURNACE LEER Application filed February 8, 1929. Serial No. 388,464.

This invention relates to mue furnace structures, more particularly to furnaces of the tunnel type for use as annealing leers in the treatment of glassware. It is a special object of the present invention to provide temperature regulation in leers for annealing glassware taken from ware-forming machines, the apparatus designed for this purpose being particularly adapted to establish and maintain the proper temperature regulation throughout the length of the leer whereby the ware is initially treated at red heat, and passed out of the leer at substantially atmospheric or room temperature.

Annealing leers are commonly constructed with muflie hearth having a flue extending therebeneath, it being customary to draw the products of combustion from the combustion chamber through the flue along the hearth by a forced draft.

It has been attempted to produce draft regulation in the furnace chamber by breaking up the flue in separate heating zones which are independently regulated to vary the temperature in the chamber. In accordance with the present invention it is proposed to utilize an uninterrupted flue passage leading from the combustion chamber and to effect the necessary temperature regulation within the heating chamber per se.

In an annealing leer heat will radiate from the mule hearth to the interior of the annealing chamber, and it is proposed to provide a simple regulating means in the form of variable resistance to the radiation of heat for controlling the heatihg temperature, pre ferably by a single adjustment and simultaneously extending the length of the first heating zone in the chamber, the regulating means eing a series of louvers which are controlled exteriorly of the furnace to vary the spacing therebetween.

Glass is annealed by means of several distinct heating cycles, the initial of which is usually termed the heat soaking zone Where the mass is brought to a uniform temperature diminishing very slowly and then subsequently accelerated. The length of this soaking period is determined by the glass thickness or general character.

A certain initial temperature may be produced with a given heat supply rate with the louvers open and the lower hearth having a conductivity rate which would diminish its surface temperature rapidly within the limits of the superimposed'louvers; similarly, the

same initial temperature may prevail with y shutters to regulate the escape of heat through` the furnace wall. These and other features, such as varying the degree of insulation by adjusting the divided wall, which may be of composite materials, will become more apparent from a consideration of the accompanying drawing, in which like reference characters designate like parts and in which Fig. l is a Sectional elevational view of an annealing leer for glassware, embodying the principles of this invention; Fig. 2 is a transverse sectional view thereof taken along the line I`II, Fig. 1 and Fig. 3 is an enlarged detail View of one end of the leer illustrating the actuating mechanism for the louvers.

Referring to the several figures of the drawing, the structure therein illustrated comprises a tunnel-forming wall structure having top and bottom Walls, 1 and 2, and side walls 3, portions of which-are constructed of refractory or other heat insulating material. At one end of the furnace this bottom wall 2 is offset to form a combustion chamber 4 having a communicating flue 5 the extended end of which is connected to a conduit 6 leading to a fan blower 7 which exhausts the conduit to set up a forced draft or suction, whereby the products of combustion from the chamber 4 are drawn through the flue. A hearth 8 of refractory tile 9 or heat-resisting alloy sect-ions, is constructed to extend the length of the combustion chamber and flue 4 ing in the high temperature zone o nace and forming a heating chamber above is necessarily and 5 respectively. This hearth element bef the furthe combustion chamber and flue.

A wire mesh endless conveyor belt 10 is disposed to operate longitudinally within the furnace chamber, this conveyor being suspended on roller supports 11 and extending from an end roller 12 at the charging end of the leer to a main drive roller 13 at the delivery end of the leer, the roll 13 being operated through a geared transmission 14 and drive motor 15. i

The conveyor belt is maintained under suitable tension by an adjusting roll 16 and a weighted roll 17 the latter maintaining tension on the belt by action of gravity. Disposed between the conveyor belt 10 and the hearth 8 are a plurality of louvers 20 which are pivotally mounted in the side walls of the furnace, by means of shafts 21, as clearly shown in Fig.'2. The louvers are in the form of double winged baflles having a central perforation for receiving the pivot shafts 21, and they are of such width that when assembled' in spaced relation in the manner shown in Fig. 3 they form a substantially closed hearth element in spaced relation with the hearth 9. The shafts are designed to project beyond the side wall 3 at one end and are provided with links or cranks 22 by means of which they are attached to the operating bar 23. By moving the bar 23 all ofthelouvers are'simultaneously pivoted to vary the open-v ing of the spaces therebetween in the manner illustrated in Fig. 1.

At the low temperature end of the tunnel the roof, as illustrated in Fig. 1, is of a reduced wall section, and is provided with heat radiating means' in the form of shutters 25 and hinged insulating members 24; which are supported in various positions radiating area at this portion of the tunnel. Instead of the members 25 the roof may be constructed of sheet metal to induce heat loss by radiation, and similar provision may be made on the side wall of the tunnel at this portion of the leer.

In the operation of the furnace the louvers 20 are regulated through the operating bar 23 to control the .heat radiating from the hearth 8 to the interior of the treating chamber whereby the temperaure in the hot end of the leer can be maintained or varied as desired. Since the hot zone of the furnace gion of the combustion chamber 4 a temperature variant will be obtained by virtue of the hearth being hottest at this point, the hearth portion in the region of the iiue being of lesser temperature than the portion immediately above the combustion chamber.

On this account the regulation eected by the louvers is in the form of a variable resistance to the radiatiom of heat from the hearth .louvers may.

to vary theymeans adjacent a portion at the charging end in the rewhereby a diminishing temperature gradient. and temperature regulation Ais adequately ef fective within the heating chamber.

Although the inventionhas been illustrated. as an embodiment of annealing leers for glassware, it will be employed in other furnace structures and for purposes other than the treatment of glassware. The louvers may be employed in conjunction with electrical resistor furnaces or naces, as may be found convenient.

Although one embodiment of the invention has been herein illustrated and described, it will be obvious to those skilled in the art that various modifications may made without departing from the principles herein set forth.

' I claim herein as my invention:

1. An annealing furnace comprising a chamber-forming wall structure, heating means adjacent the bottom wall thereof, louvers disposed within said chamber adjacent said bottom wall and adjusting means for varying theV degree of opening between adjacent louvers.

2. An annealing furnace comprising a chamber-forming wall structure, heating means adjacent said wall structure, louvers disposed within said chamber in longitudinal spaced relation with said wall, and means for adjusting said louvers.

3. An annealing furnace comprising a chamber-forming wall structure, heating means adjacent the bottom wall thereof, louvers disposed within said chamber in longitudinal spaced relation with said bottom wall, and connecting means joining said louvers and adapted for adjusting the space between adjacent louvers. l

4. An annealing furnace comprising a chamber-forming wall structure, heating of the bottom wall thereof, baiile members Within said chamber arranged in longitudinal spaced relation with the heated portion of the bottom wall, and means for adjusting said baffles to regulate heat radiation to said chamber.

5. An annealing furnace comprising a chamber-forming wall structure, heating means adjacent a portion of the bottom wall thereof, and a variable resistance element disposed within said chamber and adjacent the heated portion of said bottom wall for varying the radiation of heat from the bottom wall to said chamber.

6. An annealing furnace comprising an annealing chamber, anconveyor mounted in said chamber, a heating wall on one side of said chamber, a wall disposed between said heating wall and said conveyor comprising a.y

be evident that the regulatingy with gas or oil-burning furpluralityof movable sections, and means for means adjacent s, wall thereof, and means within said chamber for regulating the amount of heat radiating from said wall to said chamber.

" 8. In a furnace requiring a process temperature gradient, the combination of a plurality of superposed bottom walls in the heatlng zone, one of which being movable whereby the heating is variable, and a. Elm

l0 rality of 1a ers of msulation in the vcoo zone one o which is movable whereby the cooling is variable. Y

In testimony whereof I have hereunto set my hand this 7 day of February, 1929, at

Pittsburgh, Pa. A

WILLIAM A. MORTON.

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