US1795921A - Furnace - Google Patents

Description

J. F. BAKER March 10, 1931.

FURNACE Filed June 23, 1926 2 Sheets-Sheet 2 INVENTOR JohnF'Ba/(ert ATTbRNEY WITNESSES: ayw.

Patented Mar. 10, 1931 A UNITE STTS rarer oFFrce JOHN F. BAKER, 0F MANSFIELD, OHIO, ASSIGNOR TO WESTINGHOUSE ELECTRIC &

MANUFACTURING COMPANY, A. CORPORATION OF PENNSYLVANIA FURNACE Application filed June 23 1926. Serial No. 117,937.

My invention relates to furnaces and particularly to furnaces having automatic discharge means.

An object of my invention is to provide a simple and efficient automatic discharge means for a furnace that may be manufactured at a low cost.

Another object is to provide improved conveying means for a furnace. 7

Another object of my invention is to pro-. vide a tilting hearth for a furnace and automatic tilting mechanism for tilting the hearth.

Another object of my invention is to provide a control system for controlling the discharge means of a furnace. I

Another obj eot of my invention is to provide alternately operative hearth moving and hearth tilting means.

Other objects of my invention will be apparent from the disclosure.

In the present embodiment of my invention, an electrically heated furnace having an annularchamber, a motor driven conveyor therein, carrying a plurality of pivotally mounted hearths and a tilting means for tilting each hearth when it arrives at a position opposite the outlet, is provided. The tilting means is operatively interlocked with the motor for driving the conveyor so that the tilting means will operate only when the driving motor is inactive and vice versa.

In the drawing, Figure 1 is a sectonal view taken through the center line of a furnace having my improved conveying means therein and showing the hearth-driving motor in operation and the tilting motor inactive;

Fig. 2 is a view showingthe development in part of the surface of the tray-tilting cam;

Fig. 3 is a sectional view taken on the line III-III of Fig. 1; and

Fig. 4 is a diagram of the circuitsfor electrically interlocking the hearth motor and the tilting means.

Referring to the drawings a furnace 10 has a casing 11 that is supportedby supporting means 12. Suitable refractory heat-insulating means 13 is provided inside the casing. This structure constitutes no part of the present invention.

In the present embodiment of my invention,the furnace is annular and has an annular chamber 14 therein which is provided with a discharge passage 15 and with a suitable inlet which is not shownin the drawing,

since that portion of the furnace is not illustrated. In the bottom wall of the furnace, an annular passageway or runway 16 is provided which, at its upper end, opens into the annular chamber. Heating means 17, which, in the present embodiment, are electric, are

provided at the top and bottom ofthe annular chamber. A suitable conveying means is provided for conveying the material to be' heat-treated through the annular chamber.

In. the present embodiment, the conveying means comprises a wheel 18 keyed to'a vertical shaft 19. mounted in bearings 20 and 21. The rim 22 of thewheel is preferably rotatably supplate 25 secured thereon. Hinge means 26 The shaft 19'is rotatably are provided on the outer edge of the hearthsupporting plate 25 to pivotally mount a tiltable tray or hearth 27 An annular support may be substitutedfor the series of columns, if desired.

Suitable sealing means are preferably provided to seal the lower end of the annular passageway 16 from the outside atmosphere. In the present embodiment of my invention, the sealing means consists of circular concentric troughs 28 and 29 mounted on the furnace structure and adapted to receive sand or other sealing material; Mounted on the'eolumn 24: is an annular flanged member 30, the flanges of which extend downwardly into the sealing material in the troughs 28 and 29, thereby forming a seal.

} Suitable driving means is provided to drive the conveyor. As one means of driving the conveyor, I have shown an annular rack 31 mounted on the bottom of the wheel 18 and engaged by a gear wheel 32 that is keyed to the shaft 33, which is rotatably mounted in bearings 34.

A worm wheel gear is keyed to the shaft 33 and engages a worm screw 36 on the shaft of adriving or hearth motor 37. It is apparent that, when the hearth motor is operating the conveyor, consisting of the wheel 18, the columns 24, the hearth-supporting plates 25, and the hearth trays 27, will so rotate, that material placed on the hearth trays 27 will be carried through the annular chamber 14 to be heat treated.

Automatic means for tilting the hearth tray 27 when it reaches a point opposite the discharge passage 15 and thus discharge the heat-treated material, is provided. Such means, in the present embodiment of my invention, comprises a shaft 38, for tilting or inclining the hearth, as will hereinafter be made clear, slidably mounted in a vertical passageway 39 and in a guide 49and having a projection 41 on its lower end which will engage the inner edge of a hearth tray 27 whenthe shaft'38 is raised to tilt the tray. To raise the shaft 38,1 provide a tilting motor 42, preferably an adjustable speed shunt motor, which is operatively connected to a rotatably mounted cam 43 by means of worm gearing 44. The cam 43 is operatively connected to the shaft 38 by roller bearing 83. A suitable sand seal 49 may be provided to seal passageway 39.

The cam 43 is preferably a metallic cylinde provided with a groove of such shape that when in operation it will quickly. raise the shaft the desired distance, maintain it at that level for a predetermined time, and will then return the shaft to its original position during a predetermined time, preferably greater than the time taken to raise it. The cam thus serves to time the steps of the hearth tilting operation. For the sake of convenience those parts .80 of the cam groovewhich act to raise the shaft may be called the tilting surfaces; those parts 81 which maintain the shaft in raised position, the incline-maintaining surfaces; those parts 82 which permit the return of the shaft to its original position, the restoring surfaces.

As clearly shown in Fig. 1, the supporting plate 25is not so wide as the corresponding hearth tray so as to permit the projection 41 to clear the plate and engage the hearth 27 when the plate is in proper position. A roller bearing 45 may be provided on the top of the projection 41. *When the supporting plate is in such position and the tilting motor is operated, the roller bearing 45 will engage the rear edge of the hearth 27 and force the hearth to be turned or tilted about the pivot 26 and thus discharge the heat-treated material through the discharge opening 15.

Means are provided for so operatively interlocking the hearth motor and the tilting motor that the tilting motor will operate only when the respective hearth trays are in the proper position, with respect to the discharge opening 15 and the projection 41, to render the driving motor 37. inactive. Such means may comprise a commutator member 46 which is keyed to the upper end of the shaft 19 so as to rotate in unison with the conveyor. The commutator member 46 consists of an annular metallic conducting portion 47 having a series of radial projections 48. Between the radial projections 48 insulation sections 50 are located.

A brush or contact member 51 engages the top of the annular portion of the member 47. The brush 51 is connected, by means of a lead or conductor 52, to positive main conductor 53, as diagrammatically shown in Fig. 3.

A brush 54, mounted on the frame of the furnace, engages the rim portion of the commutator member 46. This brush will, therefore, beelectri'cally connected to the conductor 47 only when it is in engagement with one of the projections 48 of the conductor. Thebrush or contact member 54 is electrically connected, by means of a conductor 55, to magnet energizing coil 56 and by a conductor 57, to the negative main conductor 58. It will be obvious that, when the brush 54 engages one of the projections 48,current will flow from the main conductor 53 through the conductor 52, the brush 51. the conductor 47, the projection 48 that the brush 54 is engaging, brush 54, conductor 55, coil 56, and the conductor 57 to the negative main conductor 58.

The conveyor dr'ivingmotor 37 is electrically connected to the positive main conductor 53 by means of a conductor 59. The hearth motor, when operating is electrically connected to the negati'vemain conductor by means of a conductor 60, an electromagnetic switch 61' and a conductor 62. Fig. 3 shows the hearth motor so connected.

The electromagnetic switch6l has an energizing coil 63 which iselectrically connected to the positive main conductor 53 by means of a conductor a sliding contact switch 65 anda conductor 66. The coil 63 iselectrically connected to the negative main conduc tor by means of conductor 67 and the conductor 62. Since the switch 6l i's closed, the switch 65 is also shown as closed.

When the tilting'mo-tor is operating,.it is electrically connected to the positive main conductor 53 by means of aconductor 68, an

electromagnetic switch 69 and a conductor 70.

It is electrically connected to the negative main conductor 58 by means of a conductor 71. The electromagnet of the switch 69 is energized by means of'thc coil 56. The switch 65 consistsof a' stationary contact member 7 2 and a movable contact member'73 which is secured to an arm 74, the arm 74 being rigidly mounted on the shaft 38 and suitably insulated therefrom. The switcli 65'wil1 thus be opened when the tilting motor operates. The initial position of projection 41 is, of course, far enough below the tray to be dumped to permit disengagement of contact members 72 and 78 before the projection 41 engages the tray.

'lhe hearth motor, as previously stated, is shown in operation in Fig. 3. The commutator switch 46 will, therefore, be rotated. As shown in 3, the brush 5% has i ust started to engage the projection 1-8. This engagement of the brush 5% with the projection 4-8 is so timed as to take place when the projeo' tion 41 is in register with the hearth to be dumped. When the brush 5 f engages the projection 48, current will flow through the coil 56 of the electromagnetic switch 69, by way of the circuit which has previously been described. When the coil 56 is energized, the switch 69 is closed, which completes the circuit through the tiltint motor. This will cause the tilting motor to operate, the shaft 38 will thus be lift-ed and the-hearth 2? will that the shaft will be returned to its 1 be tilted for dumping the heat-treated material, as previously described. The inclinemaintaining surfaces 81 of the cam, will hold the hearth in inclined position for a time sufficient to permit complete discharge of heat-treated material.

lVh-en the shaft 38 .aised, bearing the contact member 3,'wi raised and the switch 35 will be opened, thus breaking the circuit th ough the coil 63 of the electromagnetic swi ch 61. The electroinagnet switch 61 will, therefore, be opened and this will breal'; the circuit through the ieartlrdriving motor 37, thus stopping the conveyor. Suitable braking means may be provided to prevent the hearth bein carried past the proper point f r being on by the projection 41f After the cam the arm 74, l also in) has rotated far enough to carry the incline-maintaining surface out of engagement with the roller l caring 83, the restoring surface 82 next comes into engagement therewith. As previously noted the restoring surface is preferably of suchsh no ltial position more slowing than it was raised. The reason for this is to permit suf icient time to elapse to charge the next hearth be fore the hearth-drivi' motor s again started and the charging op- 'ation will ordinarily require more time than the dischare oration. By substituting cams of c' shape the relative time consumed by the of the discharging operation may be c through the hearth motor and starts the motor, and the cycle of operation heretofore described, is repeated. Since the speed of the tilting motor is adjustable, the timein which the hearth is maintained, inclined, may be varied at the will of the operator.

While preferably the hearth conveying means and hearth tiltin or dumping means operate alternately only, yet the tilting mechanism will ope to if the conveying runs centinuos" bstitution of a manually operated switch ior he switch 61 will accomplish tnis result. I

While elec ric motors are hereindisclosed for opera the means for conveying the hearths thro gh the furnace, any type of prime movers may be used.

A quench tr e by be provided to ceive the material discharged through the passage 15. V

i fliile l have shown, and described a par m y :nventnn, changes may therein with-out departing from thereof, as setforth in til, it tilted du ing a predetermined pe riod of time, the r toring movement of said tilting means being enecuted during a substantially longer period of time than the discharging period.

I 2. In a furnace, a movable hearth, means to move said hear: through said furnace, tilting mechanism for periodically dumping said hearth, a motor for operating said tilting mechanism, a cam for operatively connecting said motor to said tilting mechanism, said cam being adapted totime the steps of the dumping operation in a predetermined manner.

3. In a furnace, a movable hearth, means for movingsaid hearth through saic furnace, automatic means for periodically tilting'said hearth and maintaining it tilted for a predetermined period for discharging material therefrom, said hearth moving means being controlled by saic. tilting means, the restoring period of said tilting means being substantially greater than the discharging period.

4. In a furnace, movable hearth, means for moving said hearth through said furnace and automatic means for periodically dumping material from said hearth, said automatic means being adapted to governthe timing of each step of the dumping operation in a predetermined manner.

In testimony whereof, l have hereunto subscribed my name this 17 day of June, 1926 JOHN F. BAKER.

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