US2486506A - Furnace - Google Patents

Description

NOV 1949. G. R. SYLVESTER 1 2,485,506

FURNACE Filed May 6, 1946 e Sheets-Sheet 1 INVENTOR. GEORGERSYLVESTER 1-? 1 .w L. I B H- ELIS D ATTORNEYS Nov 1, 194-9. s v s 2,486,506

FURNACE GSheets-Sheet 2 Filed May 6, 1946 INVENTOR.

GEORGE R.SYLVESTER MMMM ATTORNEYS Nov 1, 1949. G. R. SYLVESTER FURNACE 6 Shets-Sheet 3 Filed May 6, 1946 INVENTOR.

GEORGE R.SYLVESTER MQ CWM' ATTORNEYS Nov 1, 1949. G. R. SYLVESTER FURNACE Filed May 6, 1946 6 Sheets-Sheet 4 INVENTOR.

GEORGE R.SYLVE STER m trim ATTORNEYS Nov 1, 1949. I s v s 2,486,506

FURNACE Filed May 6, 1946 6 Sheets-Sheet 5 INVENTOR. GEORGE R.SYLV ESTER ATTORNEYS Nov 1, 1949.

G. R. SYLVESTER FURNACE Filed May 6, 1946 6 Sheets-Sheet 6 INVENTOR. GEORGE R. SYLVESTER VIM ATTORNEYS.

Patented Nov. 1, 1949 UNITED STATES PATENT OFFICE This invention relates as indicated to furnaces and more especially to heat treating furnaces of the type adapted to maintain a work piece at an elevated temperature for a predetermined length of time, which furnaces are usually provided with means whereby the work piece may be cooled at a controlled rate. 7

It is a principal object of my invention to provide a furnace of the character described which is particularly adapted to be used for the treatment of work pieces which require that there be a fluid line connected to the work piece during the heat treating operation although from the ensuing description of my invention it will be observed that the novel furnace is of general utility.

It is a further and more particular object of my invention to provide a furnace of the character described which is continuous in its operation, i. e. the furnace may be utilized as one component in a continuous production line.

It is a further object of my invention to provide a furnace in which the various controls over and connections with the work piece during the heat treating operation may be accomplished with a minimum of labor and by apparatus which is not only of simple and economical construction but which may be operated economically and with little likelihood of such moving parts as are associated therewith becoming deranged.

Other and more specific objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. l is a plan view partially in section of a furnace constructed in accordance with the principles of my invention;

Fig. 2 is a section view of the furnace illustrated in Fig. 1 taken on a plane indicated by the line. 22;

Fig. 3 is a view similar to Fig. 2 but showing only a portion of the furnace at a different crosssectional plane from that on which Fig. 2v is: taken;

Fig. 4 is an enlarged side elevational view of the lower end of the furnace as illustrated in Fig. 2;

Fig. 5 is a view of the apparatus illustrated in Fig. 4 taken on a plane at right angles to the plane of Fig. 4;

Fig. 6 is an enlarged part sectional, part side elevational view of the upper end of the mast in the center of the furnace as illustrated in Fig. 2;

Fig. 7 is a fragmentary sectional view of a portion of such mast showing one of the electrical slip rings of such mast;

Fig. 8 is a diagrammatic View of a furnace incorporating the principles of my invention by bein arranged for straight-line movement rather than the circular movement illustrated in Fig. 1-;

Fig. 9 is a view of a furnace somewhat similar to Fig. 8;

Fig. 10 is a sectional view of the heating zone of a furnace similar to that of Fig. 2 except that provision is made for placing a plurality of workpieces at each station of the hearth and that the heating elements are disposed vertically along opposite sides of the hearth instead of horizontally above as in Fig. 2

Fig. 11 is a plan view of the portion of the furnace shown in Fig. 10 showing a portion of the rotating hood and the stationary hearth;

Figs. 12 and 13 are sectional views respectively of the heating zone and cooling zone of a modified form of furnace taken along a plane corresponding to that through which Fig. 2 was.

taken;

Fig. 14 is a sectional view of the furnace of Figs. 12 and 13 taken along a plane through the loading and unloading zone thereof; and

Fig. 15 is a plan view of a portion of the hood and hearth of the furnace illustrated in Figs. 12-14.

Referring now more specifically to the drawings and more especially to Figs. 1 and 2. the furnace here illustrated as embodying the principles of my invention comprises as its principal features a stationary hearth I and a rotary hood 2. The hearth l in the form of construction illustrated in Figs. 1 to 7 is annular in form, is made of suitable refractory material, and supported at an elevation above the floor level by means of spaced standards 3 forming a part of a supporting framework.

The hood 2 is built up of appropriate sections of refractory material all maintained in assembled relation within a metallic framework which includes the vertically extendin legs 4 and annular brackets 5 carried by the bottom ends of such legs which brackets rest on wheels 6 by which the entire hood is rotatably supported on rails I.

While the hearth l is in the form of a full and continuous annulus, the hood, while annular in form, has a segmental portion omitted as illustrated in Fig. 1 between the five and seven oclock positions. Thus, as the hood 2 is rotated about the vertical axis of the furnace, the hearth I will be progressively uncovered to make possible the charging and unloading of the furnace.

In the preferred embodiment of my invention the cross-section of the hood over the hearth is such as to closely confine the space above the hearth which is to be occupied by the work pieces. The hearth is preferably provided in circumferential spaced points with radially and upwardly extending partitions 8 which substantially span the space within the hood over the hearth. As most clearly illustrated in Fig. 1, the hood at preferably each of its open ends such as 9 is provided with a restricted throat which coincides in cross-section to substantially the size and shape of the partitions 8 and extending for a distance equal at least to the space between one adjacent set of partitions so that the space within the hood is at all times substantially sealed from the atmosphere as the hood is rotated over the hearth.

A seal between the lower edges of the hood and the hearth is provided by means of annular brackets II! which extend into a sand trap I I carried by annular brackets I2 on opposite sides of the supporting framework 3.

Axial alignment about a vertical aXis between the hearth and the hood is insured by the provision of annular rails I3 on the inner and outer surfaces of the supporting structure 3 and with which rails rollers I4 carried by the brackets 5 are in engagement.

As previously indicated the heat treating furnace of my invention is particularly adapted for operation on devices which require a fluid connection thereto during the heat treating operation. A representative example of such a work piece is an evaporator used in conventional refrigerators. Best results can be secured in the fabrication of such evaporators if, durin the brazing operation performed by the heat treating furnace of my invention, the space within the evaporator is alternately maintained at subatmospheric or atmospheric and super-atmospheric pressures. This is accomplished by having a pipe such as I5 extend upwardly through the hearth at each work piece station so that the work piece may be connected to the upper end of the pipe by any conventional connection means which it is believed unnecessary to more particularly describe herein. The lower end of each of the pipes I5 is connected to conduits I6 and I! which are respectively controlled by means of valves I8 and I9. The valves l8 and I9 are preferably spring loaded so that in their normal state they are closed. Various forms of valves capable of performin this function and constructed as above explained are available on the market and will, therefore, not be described in greater detail.

The valves I8 and I9 are conveniently actuated at the appropriate time during the heat treating cycle by means of cam tracks 28 and 2i respectively, which cam tracks are carried on the lower ends of brackets 22 and 23 depending fromthe main framework 4 of the hood. Thus, if during the first predetermined interval during the heat treating cycle a partial vacuum is to be maintained in the work piece, the hood will have mounted thereon adjacent its forward end a cam track which will depress and open the valve in the line leading to a vacuum connection, and at the conclusion of that heat treating interval such valve will then be closed by an elevation in the contour "of the aligned cam track and air or other gas under atmospheric or superatmospheric pressure introduced to the interior of the article being treated by a similar actuation of the other valve by means of a similar cam track.

The lower end of the pipe I5 passes through a bracket 24. Around the pipe I5 is a spring 25 which bears at one end on the elbow or other projection on the lower end of the pipe I5, and at its upper end bears on the bracket 24 so as to urge the pipe I5 downwardly. This expedient insures that when the pipe I 5 is connected to the work piece the latter will be held in position on the hearth. The provision of such spring also makes possible the utilization of a connecting means between the pipe I5 and the work piece which relies upon spring tension to maintain a seal.

A furnace constructed in accordance with my invention makes possible the provision of separate heatin and cooling zones in the following manner:

In the heating zone the hood caries in the space above the hearth, as viewed in the lefthand portion of Fig. 2, a plurality of resistance or other heating elements 26 such as hot oil or gas which may be connected by means of a lead such as 2'1 to a sli ring assembly S, the construction of which will be explained in greater detail at a later point. I

In the cooling zone the hood will carry a cooling or heat exchange coil generally indicated at 28 through which cooling water for example may be circulated by being introduced thereto through the pipe 28 and discharged therefrom through the pipe 29. The pipe 28 is connected to the mast 30 by means of a slip connection T, the construction of which will be explained at .t. a later point. In order to insure rapid circulation of air through the cooling zone in the furnace the hood adjacent the coolin zone may be provided with a circulating fan generally indicated at 1-H which is driven by means of a motor 32. The motor 32 is energized electrically by means of a lead 33 connected to another slip ring device S on the mast 30.

It will be observed that the effluent from the cooling coil 28 through the pipe 29 is discharged into an open ditch at the center of the furnace and drained to 'a suitable catch basin not shown.

The hood is rotated with respect to the hearth by means of an electric motor such as 34 carried by the hearth frame and connected to one of the wheels 6 by means of a cross-shaft 35 and a sprocket chain 36. The motor 34 may be energized from the same lead 33 which is utilized to energize the fan motor 32.

The slip connection S previously described is illustrated in Fig. '7 and comprises a stationary part 31 rotatably supported by means of antifriction bearings 38 on a radially outwardly extending flange 39 on the mast 30. The mast 30 has secured thereto radially extending arms 40 which at their inner ends are connected to an electrical lead such as 4| and at the outer ends carry a contact wheel 42 which is in engagement with an annular" ring 43 of conductive material to which one side of the lead 33 is connected.

The other side of the lead 33 is connected to a similar ring 44 with which another arm 45 is in communication through a wheel 46,

The slip connection T by means of which fluid is introduced to the conduit 28 comprises a stuff- .ing box generally indicated at 41 mounted on the upper end of the mast 30 and into which projects a stationary sleeve 48. The sleeve 48 is connected in any suitable fashion to an elbow 49 or other part of the pipe 28.

As viewed in Fig. 1 and as previously explained during the normal operation of my furnace, the loading and discharging station progresses around the stationary hearth I. In order to facilitate charging and unloading the furnace, I provide a platform 50 which is carried on the track I and carried along with the hood by means of a, bracket 52 connected to the hood framework. The operator whose duties are to charge and unload the furnace will stand on the platform 50 and be carried around the furnace with the hearth and thus the operator will always be positioned at the charging and unloading station.v The treated and untreated work pieces are taken away from and brought to the moving operators station by means of a suitable crane such as 53 which operates on a circular track 54 arranged concentric with the axis of the furnace.

While in the preferred embodiment of my invention the hearth and hood are circular, thus making possible the utilization of the furnace as an element of a continuous production line, nevertheless these same objectives may be achieved in a measure at least by an arrangement such as that illustrated in Fig. 8 in which the hearth 55 is arranged on a straight line and the hood 56 is arranged for straight line travel relatively to the stationary hearth. In this modification of the invention the hood is provided with a heating zone generally indicated at 51 and a cooling zone generally indicated at 58. The general design, construction, and mode of actuation of the hearth, hood and associated mechanism as illustrated in Fig. 8 is similar to that illustrated and described in Figs. 1 to '7 except that the parts instead of being circular and endless are arranged in a straight line. In the form of construction illustrated in Fig. 8 the normal operation of the hood during the heat treatment of the work pieces is from right to left at a rate determined usually by the length of the hood heating and cooling sections and the time during which the heat treating operation need be carried out. After the hood has completed its travel at this predetermined speed from the extreme right-hand end to the extreme left-hand end, then the carriage carrying the hood is quickly returned to the right-hand end of the structure and the sequence repeated.

When it is not necessary to provide controlled cooling of the work pieces then an arrangement illustrated in Fig. 9 may be employed which is generally similar to that illustrated in Fig. 8 with the exception that the controlled cooling zone is omitted. When this type of structure is employed then the heat treating operation may be carried out during both directions of travel of the hood with respect to the stationary hearth.

Insofar as the parts in the modified furnaces of Figs. 10 and 11 and Figs. 12-15 are the same or similar as those in Figs. 1-'-'7, like numerals have been used and the prior description is applicable except as hereinafter noted.

The furnace shown in Figs. 10 and 11 is the same as that of Figs. 1'! except that provision is made for treating several workpieces simultaneously in each of the sections defined by the partitions 8. This is accomplished by providing a plurality of shelves 59 and a plurality of pipes [5, one pipe I5 being associated with each shelf. The pipes l5 are adapted to carry a fluid pressure medium pulsated in the same manner as in the form of furnace illustrated in Figs. l-"l. In order to provide a more uniform heat distribution, the heating elements 26 are disposed vertically on opposite sides of the shelves 59 rather than being horizontally disposed above a single workpiece as in the left-hand portion of Fig. 2.

In the 'modified furnace illustrated in Figs. 12-15 there are plural shelves 59 and plural pipes l5 and vertically disposed heating elements 26 as in Figs. 10 and 11, but there is in addition a pipe 60' extended upward through the hearth I controlled by a valve l9. The purpose of such pipe 60 is to permit carrying on of the heat treating operation in a controlled or neutral atmosphere by supplying to the space around the hearth a suitable inert gas. Such valve controlled pipe 60 may also be used in the furnaces illustrated in Figs. l-11 whether or not there are any pipes l5 connected to workpieces. That is to say that my furnaces are not limited to use in treating refrigerator evaporators or the like but are readily usable in treating all kinds of articles. As a matter of fact, the inert gas may be piped into the treating chamber through pipes [5 rather than providing separate pipes 60.

I It is also to be noted that in the furnace of Figs. 12-15, the wheels 6 are grooved whereby the rails l3 and rollers l4 shown in Fig. 2 may be dispensed with, sufi'iciently accurate alignment between the hearth and hood being attained through the grooved wheels 6.

In the furnace of Figs. 12-15 instead of employing partitions 8 on the hearth, separate hoods 62 are employed, each having its open bottom end seated in a, sand trap 6|. Each hood can be lifted upwardly to unload and charge the hearth and then lowered prior to the hood 2 rotating to a position to enclose the same. For convenience in lifting and. lowering the hoods 62, an overhead circular rail 63 which is concentric to the hood 2 movably carries several chain and pulley hoists 64, the chain portion of which can be quickly hooked to the top of any hood 62 which it is desired to lift. Another difference in this furnace is the particular construction of the cooling zone in which, as shown in Fig. 13, the blower 3| is disposed centrally above the hood 62 and the cooled air which is drawn through the cooling coil 28' is forced downwardly and is diverted down opposite sides of each hood 62 and the heated air is drawn up through spaces on opposite sides of the hood 2 as shown by the arrows in Fig. 13.

While not shown in the drawings, it is contemplated that instead of the partitions 8 or the hoods 6 2, the hood 2 may be provided with a vertically slidab'le door at each open end thereof and between the heating and cooling zones thereof. In such a furnace the hood 2, instead of being moved at a uniform rate of speed, could be indexed rather rapidly from one position to the next and raising such doors to clear the workpieces during such indexing. The hood 2 can be indexed one section at a time or, if desired, it can be indexed the entire number of sections between the ends thereof.

Other modes of applying the principle of the invention may be employed, change being made as regards the details describe-d, provided the features stated in any of the following claims or the equivalent of such be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. In a heat treating furnace, the combination of a hearth for supporting a hollow workpiece to be treated, a hood enclosing a portion of the longitudinal extent of said hearth, a fluid conduit on said hearth for connection with the workpiece, a valve controlling the fluid supply into the workpiece through said conduit, means for moving said hearth and hood longitudinally relative to one another to expose the workpiece and means on said hood cooperatively engaging said valve for closing said valve during such exposure,

2. In a heat treating furnace, the combina tion of a hearth for supporting a workpiece to be treated, a hood enclosing a portion of the longitudinal extent of said hearth and defining therewith a workpiece treating zone, a fluid conduit on said hearth, and a valve controlling the fluid supply into such treating zone, said hearth and said hood being longitudinally movable relative to one anotherto progressively expose a portion of said zone to permit unloading of workpieces therefrom, and said hood including cam means engageable with said valve for closing said valve during such exposure.

3. In a heat treating furnace, the combination of a stationary hearth upon which a plurality of separate hollow :work pieces are adapted to be supported in spaced relation longitudinally thereof, fluid conduit means on said hearth for connection with said work pieces, separate valves respectively controlling the fluid supply into the work pieces through said conduit means, vertically extending battles on said hearth between the work stations thereon, a hood having a longitudinal extent less than said hearth and laterally enclosing that portion of the hearth to which it is adjacent, said hood divided into different treating zones longitudinally thereof and having a restricted throat at at least one end thereof, said throat having a cross-section substantially the same as the size of said bafiies and a longitudinal extent equal to at least the distance between adjacent baflles, temperature modifying means in each of the zones of said hood, means for moving said hood along said hearth, and cam means on said hood engageable with said valves for operating the same during movement of said hood.

4. In a heat treating furnace, the combination of a stationary hearth upon which a plurality of separate hollow work pieces are adapted to be supported in spaced relation longitudinally thereof, fluid conduit means on said hearth for connection with said work pieces, separate valves respectively controlling the fluid supply into the work pieces through said conduit means, vertically extending bafiles on said hearth between the work stations thereon, a hood having a longitudinal extent less than said hearth and laterally enclosing that portion of the hearth to which it is adjacent, said hood divided into different treating zones longitudinally thereof and having a restricted throat at at least end thereof, said throat having a cross-section substantially the same as the size of said bafiies and a longitudinal extent equal to at least the distance between adjacent baiiles, temperature modifying means in each of the zones of said hood, means for moving said hood along said hearth, and means carried by said hood for progressively actuating said valves as said hood moves along said hearth.

5. In a heat treating furnace, the combination of a circular stationary hearth upon which a plurality of separate hollow work pieces are adapted to be supported in spaced relation circumferentially thereof, fluid conduit means on said hearth for connection with said work pieces, separate valves respectively controlling the fluid supply into the Work pieces through said conduit means, radially and vertically extending baffles on said hearth between the work stations thereon, a part-annular hood having a circumferential extent less than said hearth and laterally enclosing that portion of the hearth to which it is adjacent, said hood divided into different circumferentially adjacent treating zones and having a restricted throat at at least one end thereof, said throat having a cross-section substantially the same as the size of said bafiies and a circumferential extent equal to at least the distance between adjacent bafiles, temperature modifying means in each of the zones of said hood, means for progressively moving said hood around over said hearth, and means carried by said hood for progressively actuating said valves as said hood moves around said hearth.

6. In a heat treating furnace, the combination of a stationary annular hearth for supporting a hollow workpiece to be treated, a hood enclosing a portion of the longitudinal extent of said hearth and defining therewith a workpiece treating zone, a fluid conduit on said hearth for connection with the workpiece, valves connected to sources of fluid at difierent pressures and selectively actuatable to supply fluid into the workpiece through said conduit, means for moving said hood relative to said hearth, and means carried by said hood for alternately actuating said valves as said hood moves around the portion of said hearth on which the workpiece is supported.

7. In a heat treating furnace, the combination of a stationary annular hearth for supporting a hollow workpiece to be treated, a hood enclosing a portion of the longitudinal extent of said hearth and defining therewith a workpiece treating zone, a fluid conduit on said hearth for connection with the workpiece, valves connected to sources of fluid at difierent pressures and selectively actuatable to supply fluid into the workpiece through said conduit, means for moving said hood relative to said hearth, and means carried by said hood for alternately actuating said valves as said hood moves around the portion of said hearth on which the workpiece is supported and for simultaneously closing said valves when said hood moves to expose the portion of said hearth on which the workpiece is supported.

8. In a heat treating furnace, the combination of a hearth for supporting a workpiece to be treated, a hood enclosing a portion of the longitudinal extent of said hearth, a fluid conduit on said hearth for connection with the workpiece, a valve controlling the fluid supply to the workpiece through said conduit, means for moving said hearth and hood longitudinally relative to one another to expose the workpiece, means for closing said valve during Slllch exposure, and spring means associated with said conduit operative to yieldably urge said conduit downward and thereby yieldably press the workpiece to which it is connected against said hearth.

GEORGE R. SYLVESTER. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,749,866 Winzer Mar. 11, 1930 1,798,649 Bartling Mar. 31, 1931 1,809,727 Sanders June 9, 1931 1,903,909 Cope et al Apr. 18, 1933 2,015,699 Trainer et al Oct. 1, 1935 2,231,956 Schwier Feb. 18, 1941 2,296,791 Keener et al Sept. 22, 1942 2,417,063 Cooper Mar. 11, 1947 FOREIGN PATENTS Number Country Date 273,894 Italy May 5, 1930

Images