US2121109A - Electric furnace - Google Patents

Description

June 21, 1938 c. M. wElNHElMl-:R 2,121,109

ELECTRIC FURNACE Filed April 22, 1955 4 Sheets-Sheet l u w vm.

June 21, 1938. C, M, wElNHE-lMER 2,121,109

ELECTRIC FURNACE Filed April 22, 1935 4 Sheets-Shea?l 2 @PET Ear June 2l, 1938. c. M. WEINHEIMER ELECTRIC Y FURNACE Filed April 22, 1935 4 Sheets-Sheet 3 m.. @wm

v June 21, 1938.

c. M. WEINHEIMER 2,121,109

ELECTRIC FURNACE Filed April 22, v1955 4 sheets-sheet 4 gif@ 56 d Patented June 21,1938

ELEe'rnrc FUnNAcE Claude M. Weinheimer, Detroit, Mich., assignor to Detroit Electric Furnace Company, Detroit, Mich., a corporation of Michigan Application April zz, 1935, serial N0.'1(z,s17

13 Claims.

The present invention relates in general to electric furnaces principally of the rocking type and is more particularly concerned with improvements in construction and operating means, whereby the furnace may be more easily repaired and more eillciently and safely operated.

Although the invention has been described herein as applied to an electric furnace, it will be apparent to one skilled in the art that the invention may. with equal facility, be adapted for use in connection with other devices.

It is a further object of the present invention to provide in a furnace of the ro'cking type, improved means to enable longitudinal expansion and contraction of the melting chamber shell in response to changes of temperature.

It is a further object of the invention to provide improved supporting means for a rockably mounted melting chamber'slrell wherein the supporting parts are so arranged that rocking of the shell will be unaffected by its longitudinal expansion and contraction due to changes of tem.

perature.

It is also an object of the invention to provide in a furnace having an enclosing shell structure lined on its interior to define a melting chamber improved means for securing the end portions of the shell so as to enable bodily movement thereof during expansion and contraction of the lining due to temperature changes.

In the prior art devices of the herein described type, it has been customary to provide the melting chamber with circumferentially extending rails or tracks which were supported on rollers or wheels having lateral flanges that were so disposed as to engage opposite sides of the rails or tracks respectively. With this arrangement, the flanges of the wheels tended to maintain the spacing of the rails substantially constant so that during expansion and contraction ofthe shell to which the rails were secured, the rails would be forced against one or the other of the flanges of the wheels, with the result that there was considerable interference with the proper operation of the rocking mechanism.

To the end that the furnace shell may be free to expand and contract and vary the spacing between the rails Without in any way interfering with the rocking operation, this invention prol poses to provide the rollers or wheels with a single lateral flange rather than two lateral flanges, whereby the tracks may be shifted relative to the faces of their associated wheels in an axial direction thereto during changes in the temperaturev of the furnace shell.

Since the furnace shell is substantially of cylin drical construction and forms with its end portions a closed structure which is lined with a refractory material,` it will be apparent that the prior art constructions, wherein the end sections or portions were welded or otherwise ilxedly secured in place, the entire distance around their periphery, longitudinal expansion of the shell could not readily take place. To overcome this diillculty, it is proposed to floatingly mount the end sections of the shell so that the end sections may bodily move as the shell expands and contracts under temperature changes.

Moreover, the end portions are readily removable to enable rebricking, repairing, etc., of the lining.

A still further object of the herein described invention resides in the provision of an improved rocking and safety mechanism which is extremely ilexible in operation and is so designed as to shut oil.' the rocking mechanism in the event that the furnace shell should for any reason be rocked past pre-determined limits.

Still another object of the invention is to provide an improved electric reversing mechanism in conjunction with an electric brake mechanism, whereby the rocking motion of the furnace is eili caciousiy terminated at the positions oi reversal.

Other objects and features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate a single ernbodiment thereof, and in which Figure 1 is a view in elevation of an electric furnace of the rocking type embodying the principles of the present invention;

Figure 2 is an end view of the same;

Figure 3 is an enlarged transverse sectional view showing the cooperative parts of the phase 40 present invention, there is shown in Figure l an electric furnace of the rocking type which comprises an oscillatably mounted drum or shell deiining a melting chamber.

lhe drum is supported on a frame structure Il which includes a pair of pedestals II and I2 longitudinally spaced relative to the axis of the rotatable drum. Each of these pedestals serves as a support for a pair of rotatably mounted wheels Il and I4 which are circumferentially spaced relative to the drum.

The furnace drum or shell comprises a substantially cylindrical casing Il which is closed at either end by an end section Il. The interior of therdrum is lined with suitable refractory material to denne a melting chamber, and the cylindrical casing Il is provided with a charging door generally indicated by the numeral it which is of the usual construction and enables charging of the melting chamber with metal to be melted. This charging door also incorporates a pouring spout I1 to enable pouring of the metals which have been melted.

The drum is oscillatably supported on a pair of rails or rockers Il and I2 which are longitudinally spaced of tbe drum so, as to be disposed near the respective ends thereof. These rails are each secured along their inner sides by a plurality of right angle brackets 2l having one leg. such as 2| which is welded or otherwise permanently secured to the casing Il and its other leg 22 secured to the rail as by bolts 23. 'Ihe outer sides of the rails are supported by similar brackets as shown at 24, except that in this case the leg of the bracket which is associated with the casing .il is removably secured thereto by means of a bolt 2l.

Ihe arrangement Just described for securing the rails relative to the drum, it will be observed, enables the rails to be easily removed from the drum. This is accomplished simply by removing the securing bolts 22 and 2l, whereupon the brackets 24 may be removed to thereby permit therailstobeshiftedclearoftheendsofthe drum.

The outer peripheries of the rails I2 and I9 are engaged by the outer surfaces of the wheels I2 and I4 so that a rolling support is provided and the drum may be oscillsted forward and backward to agitate the metal in the melting chamber during the melting operation.

As previously constructed in the prior art furnaces of this type, the supporting wheels il and I4 were provided with lateral flanges which were disposed on either side of the associated rails, these flanges serving to guide the rails and prevent axial displacement of the drum relative to the supporting structure. This arrangement has been found disadvantageous in that it did not suitably permit shifting of the rails relative to the wheels during expansion and contraction of the drum due to temperature changes. 'I'hat is, when the drum expanded longitudinally, the rails would bind with the outermost flanges of the wheels, and conversely when there was contraction there would be a binding with the inner flanges of the wheels, whereby the rocking of the drum was interfered with.

To overcome this diillculty and enable the drum to expand and contract without interfering with the rocking operation, the wheels I3 and i4 are provided with a single ilange 26 which is preferably placed at the inner edge of each wheel. By making the wheel surfaces wider than the rails, it will be apparent that the spacing between the rails may be increased without interfering with the rocking movement of the drum.

In the prior art furnaces, the end sections Il of the drum were welded or otherwise secured about their entire periphery to the casing Il. It was found that this manner of securing the end sections was objectionable in that as the lining of the drum expanded and contracted due to temperature changes, the forces exerted in the end sections were not properly relieved. To overcome this objection, the end sections of the drum in the present invention are provided with a plurality of circumferentially spaced lugs 21 which are secured at their inner ends as by welding 28 to the end sections and are outwardly deflected or cut away as shown at 29 to provide a. space between the lugs and the end sections. The outer end of each lug is hinged as shown at 30 to a hinge member ll which is permanently secured to the outer surface of the casing I5. Moreover, the connecting hinge pins are easily removable so that when all the hinge pins are removed the end sections may be easily removed for repairing, rebricking or the like of the refractory lining.

In this arrangement, it will be seen that the section I8 is floatingly mounted for axial movement, and that during this movement there will be a slight flexing of the lugs 21. Now, as the drum lining expands and contracts longitudinally oi' the furnace drum, the end sections are free to move outwardly and inwardly without setting up undue stresses in the drum.

In the embodiment shown on the drawings, the drum is oscillated by means of an electric motor 32 which has its driving shaft connected through suitable worm and wheel gearing 22 to one of the rail supporting wheels I2. It will be evident that when the wheel I1 is rotated in one direction, the drum will be oscillated accordingly in one direction and when the wheel I2 has its motion reversed, the motion of the drum is likewise reversed.

Such operation necessitates reversing the direc tion of rotation of the motor 32 and for this purpose it is proposed to furnish a multi-phase motor, in this instance a three-phase motor, and reverse its direction of rotation by the expedient of changing the phase relationship of the electrical connections thereto, in a manner wellknown in the art.

Although the drive just described is of the friction type, it will be apparent that the drum may be driven through suitable gearing. Generally indicated by the numeral I4 is an automatic reversing mechanism which is adapted to change the phase relation of the motor circuit in response to the rocking action of the furnace drum. Moreover, this reversing mechanism is adjustable to increase or decrease the interval between reversals of the motor and thus provide greater or lesser rocking oi the furnace drum as desired.

This mechanism comprises a main shaft 3l which is rotatably supported in suitable bearings, one of these'bearings being shown at 3l and carries a plurality of insulatingly supported contact blocks 28 which are adapted, upon oscillation of the shaft 3S to cooperate with a set of contacts 35 or a. set of oppositely disposed contacts 40, the contacts of each set being suitably separated by barriers as shown at 4I. The contacts 39 are each electrically connected with terminals 42 and the contacts 40 are connected with terminals 43 which 'Il may be connected by suitable wiring into the supply circuit of the motor 32 in a manner which will subsequently be explained in detail.

Rotatably mounted on the shaft 36 is a gear 44 which is driven by a. lpinion 46 with which it meshes. This pinion is rotatable with an auxiliary shaft 46, this shaft having keyed or otherwise secured to its other end a sprocket wheel 41, as

shown in dotted lines in Figure 2, which is lconnected thru -a chain 48 to a sprocket wheel 43 on the same shaft and rotatable with one of the wheels i4. It will therefore be evident that, depending upon the direction in which the furnace drum is being rotated, the gear 44 will correspondingly rotate in first one direction and then the opposite direction.

The gear 44 is provided with a segmental opening 58 within which an arm 5I is pivotally swing-n able for a limited distance, the arm I being pivoted at its lower end at 52. The arm 5I is normally held at its mid-position of its movement by oppositely disposed spring actuated plungers 53 and 54, these plungers being respectively pushed against the arm by compression springs 55 and 56. Each of these plungers is reciprocally mounted within aA housing 51 which surrounds the spring and is secured to the gear I 44 as by screws 58. The outer or free end of the arm 5I is` laterally deflected to form an abutment nger 59 which is adapted to be moved from one to the other of a pair of adjustable stop members 60 and 6I.

The stop members 60 and 6| are formed by deecting the outermost ends of a pair of radially extending indexing arms 62 and 63 respectively which are rotatable with and may be angularly adjusted relative to eachl other on an internal gear 64, this gear being rotatably mounted on the shaft 36.

The peripheral margin of the gear 64 is extended to form a flange 65 provided throughout its A length with a series of openings 66 any one of which is adapted to receive the end of a spring projected pin 61 carried by one of the indexing arms 62 or 63. The pin 61 may be withrawn from its associated opening 66 by means of a manually operable handle 68, whereby the associated indexing lever may be moved to desired position and again latched by releasing the handle 68,

whereupon the plunger or pin 61 will be moved into one of the holes 66.

The teeth of the internal gear 64 mesh with a plurality of idler pinions 63, these pinions being rotatably supported in fixed positions on a bracket which forms an integral part of the housing structure. The idler pinions 69 mesh with a gear 1l which is keyed or otherwise secured to the main shaft 36. f

The drum, as shown in Figure 2, has been rotating in a clockwise direction and is just reaching the position where it is to be reversed by the reversing mechanism. ASince the gear 44 rotates in the same direction as the drum, it will be evident that the finger 59 will be carried against the stop 60 to move the gear 64 in a corresponding or clockwise direction as viewed in Figure 5. .This movement of the gear 64 operates through the idling pinions 68 and gear 1I to move the shaft 36,

as viewed in Figure 3, in a counterclockwise direction so that the contact piece 38 will be moved from the set of contact terminals 39v into engagement with .the set of contact terminals 40. In this latter position, the phase connections of the electrical circuit to the motor are such that the direction. of lmotion lof the motor will be reversed `and the drum will be operated in the reverse direction.

The drum will continue to rotate in the opposi direction until the finger 59 engages the sto member 6I on the indexing arm 63, whereupo'n the shaft 38 will be actuated in the opposite direction to return the contact pieces 38 into engagement with the set of terminal contacts 38 for again reversing the direction of rotation of the motor.

It will be evident that the interval between reversals of the motor 32, and consequently the amount of rock of the furnace drum may be increased or decreased simply by adjusting the indexing arms 62 and 63 to different positions on the gear 64.

Secured to the shaft 36 is a hand lever or wrench 12 by means of which the shaft 36 may be rotated to manually operate the contacts for reversing the direction of rotation of the motor.

Referring to Figure 5, detent means are shown for resiliently latching the gear 64 in shifted position. It will be evident that this gear during the reversing operation will be shifted a relatively small amount. The outer periphery of the gear is provided with a pair of spaced recesses 13 and 14' which are disposed at the limits of travel of the gear and are adapted to receive a ball which is engaged by one end of a spring 16' having its other end in engagement with an adjusting screw 11' by means of which the spring pressure may be increased and decreased. In one of its shifted positions, the gear 64 will be resiliently latched by virtue of the ball 15 engaging in the recess 13. When the gear 64 is shifted so as to bring the recess 14' into alignment with the ball 15', the gear will be latched in this position.

As a safety feature, a cam strip 13 is secured longitudinally along the outer side of rail I8 to spacer lugs 14 by means of bolts 15. The ends of this strip are terminated at such positions that if the drum is rocked past its maximum limit, then an end of the cam strip will actuate a limit switch 16 to shut down the motor 32 by opening a magnetic contactor 11 in the line. Jogging operation is then accomplished by pushbutton control 18.

It will be observed that whenever the furnace has been rocked to and remains in the dangerous region the cam 13 will hold the switch open and will not enable it to close until the furnace has been moved from the danger region. With this arrangement, an inexperienced operator cannot `render the switch 16 inoperative as long as the furnace is in the danger region.

More specifically, the electrical connections of the control apparatus will be more fully understood by referring to Figure 6. The power supply for the motor is from a three-phase source A-B-C which` is connected through fuses or disconnecting switches 19 to the contacts of the magnetic contactor 11 having an operating coll 80 and thence through the controller of the reversing mechanism 34 to the motor 32. Connected Vto one phase of the motor supply circuit is an operating coil 8| of a magnetic brake, generally indicated at 82, so arranged that when the motor y is deenergized it is moved to braking position under the influence of a spring 83, and moved to released position when the motor is energized. The operating coil 80 of the magnetic contactor is connected across phase A-C and the normally closed limit switch 16 and normally open pushbutton 18 are connected in multiple for controlling the energization and deenergization ot the control coll l0.

Assuming that the reversing mechanism has operated so that the contact pieces 38 have moved into association with the set of contacts 39', with the contacts 16 of the limit switch closed and the line switches 19 closed, the contactor 11 will close and the motor will operate in forward direction, the magnetic brake 82 being released as soon as the motor is energized.

'Ihe motor then rotates the drum to its predetermined limit in that direction whereupon the reversing mechanism operates as previously described to move the contact pieces Il into association with the set of contacts 40. In other words the motor is now reversed. It will be observed that in the forward position of the motor the phase relationis A-B-C, but that when the controller 34 is actuated to reverse position, the phase relation at the motor is B-A-C.

Considering that the motor is operating in either direction and that the furnace for some reason is rotated too far, then the cam member 13 will open the contacts of the limit switch 1B to deenergize operating coil B of the contactar 11, whereupon it opens and disconnects the motor from the source of supply. Operation must now be by means of pushbutton 18 which may be closed to energize operating coil 80 to close the contactor 11 to secure jogging movement of the furnace.

During the jogging operation the controller 34 may be manually controlled by means of the operating wrench or lever 12 to secure either forward or reverse movement, as desired.

From the foregoing, it will be apparent that the herein described invention provides an improved furnace of the rocking type having improved shell construction and supportingiarrangement to take care of expansion and contraction of the shell without damaging or affecting the operation of the furnace; which permits the shell end sections and rocking rails to be readily removed; and which has improved rocking and safety mechanisms for effecting and controlling the rocking of the drum.

Now, it is of course to be understood that although I have described in detail the preferred embodiment of my invention, the invention is not to be thus limited but only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

l. A furnace having a shell structure including end sections, a lining for said shell defining a melting chamber, and deilectable lugs hingedly connecting the end sections at spaced intervals to the shell, whereby the end sections may move l relative to the shell during expansion and contraction due to temperature changes.

2. A furnace having a. shell structure including end sections, a lining for said shell defining a melting chamber, and deilectable lugs hingedly connecting the end sections at spaced intervals to the shell for enabling movement of the end sections during expansion and contraction due to temperature changes, said hinge connection having removable hinge pins, whereby the end sections may be detached to facilitate repairs and changes in the lining.

3. In a device of the character described, an oscillatably supported shell structure defining a chamber, power means for alternately oscillating the shell in opposite directions, means controlling the power means, and means to render the power means inoperative upon operation of the shell past predetermined limits.

4. In a device of the character described, an oscillatably supported shell structure deilning a chamleff power means for alternately oscillating the shell in opposite directions, means controlling the power means, and cam actuated means to render the power means inoperativeupon oscillation of the shell past pre-determined limits.

5. In a device of the character described, an oscillatable shell structure defining a chamber, power means for alternately oscillating the shell in opposite directions, means controlling the power means, means to render the power means inoperative upon oscillation of the shell past predetermined limits, and braking means operative to bring the oscillating shell to a stop when the power means is deenergized.

6. In a device of the character' described, an oscillatablysupported shell structure defining a chamber, reversible electric power means for alter nately oscillating the shell in opposite directions, controlmeans for reversing the power means, limit switch means responsive to the oscillatory movement of the shell and operative to deenerglze the power means, and auxiliary control means for temporarily energizing the power means for jogging movement of the shell.

7. In a device of the character described, an oscillatably supported shell structure defining a chamber, reversible electric power means for alternately oscillating the shell in opposite directions, control means for reversing the power means, limit switch means responsive to the oscillatory movement of the shell and operative to deenergize the power means, auxiliary control means for temporarily energizing the power means for logging movement of the shell, and an electrically-controlled braking mechanism for the power means, said mechanism being effective to stop the power means when the power means is deenergized and operative to release the power means when it is energized.

8. A rocking type furnace having a melting chamber adapted to be oscillated alternately in opposite directions by an electric motor energizable from a polyphase source of supply, wherein the reversal of motion of the chamber is accomplished by changing the phase relationship of the supply connections to the motor, and means for interrupting the power supply to the motor upon movement of the melting chamber' past predetermined limits.

9. A rocking type furnace having a melting chamber adapted to be' oscillated alternately in opposite directions by an electric motor energiz able from a polyphase source of supply, wherein the reversal of the direction of motion of the chamber is accomplished by changing the phase relationship of the supply connections to the motor, and means for interrupting the power supply to the motor upon movement of the melting chamber past predetermined limits, said means including cam means supported for movement with said chamber.

l0. In combination, a plurality of oppositely disposed contact terminals, an oscillatory Contact piece adapted to engage one or the other of said contact terminals when moved in either direction from neutral positions, means connecting said oscillatory Contact piece with a rockable furnace drum, whereby movement of the drum will cause the contact piece to alternately move from one set of contact terminals to the other, adjustable means determining the positions in the movement of the drum at which the contact piece will be moved, and manually operable means for independently actuating the contact piece.

1l. The combination comprising a rockable drum, polyphase power means for driving the drum, and control means for alternately changing the phase relationship of the electrical connections to the power means at predetermined positions of the drum, whereby the drum is alternately driven in opposite directions, said means comprising oppositely disposed sets of contacts, an oscillatable contact piece adapted to selectively cooperate with the sets of contacts, said contacts being connected in circuitI with said power means, a rotatable member connected for movement with the drum and having a projecting part, and means rotatably connected with said contact piece including an element having a pairof stop members disposed on opposite sides of the projecting part and in the path of movement thereof, the

spacing between said stops being adjustable, whereby the engagement of the parts with a stop will move the contact piece from one set of contacts to the other, and means manually operable to independently oscillate the contact piece.

12. In a device of the character described, a shell structure mounted for rotative movement and defining a chamber, power means for rotating said shell, switch means for normally energizing and deenergizing the power means, a switch responsive to a predetermined rotative movement of said shell and operable to deenergize the power means, whereby rotative movement of the shell is arrested, and auxiliary control means for temporarily energizing the power means for jogging movement 'of the shell.

13. In a device of the character described, a shell structure mounted for rotative-movement and defining a chamber, power means for rotating said shell, a normally closed limit switch operable to open position in response to a predetermined rotative movement of said shell, a magnetic contactor for energizing and deenergizing said power means, said contactor having an operating coil energized through said limit switch, and a switch connected in parallel with said limit switch for energizing and deenergizing the contactor operating coil for jogging movement of the shell, when the limit switch is open.

CLAUDE M. WEINHEIMER..

Images