US1514268A - Controlling mechanism - Google Patents

Description

Nov. 4

D. V` STEWART CONTROLLING MECHANI SM 1923 3 Sheets-Sheet 1 Filed July 19,

Nov.'4 1924. V 1,514,268

. x D. v. STEWART CONTROLLING MECHANI SM Filed July 19, 1923 3 Sheets-Sheet 2 FORWARD Nov. 4 1924. l

D. V. STEWART CONTROLLING MECHANI SM 'nleg July 19, 192s 3 Sheets-snee t 3 'making a short circui Patented Nea4, 1924.

1,514,268 TES PATENT oFFlcl-z.

nAvIn v. STEWART, or COLUMBIANA, omo.

GONTROLLING MECHANISML Application led July 19, 1923.' Serial No. 652,586.

To all whom it'may concern: Be it known that I, DAVID V.. STEWART, a citizen of the United States, and resident of Columbiana, in the county of Columbiana' and State of Ohio, have invented certain new and useful Improvements in Controlling Mechanisms, of which the following is a specification.

Thisinvention relatesto electric furnaces and more particularly to means-'for automatically controlling the low of electric current to the electrodes of such furnaces. One object of the present invention is to provide suitable apparatus adapted to automatically break the electrical circuit to the electrodes when the furnace is tilted.

Heretofore hand operated means have been provided for breaking the electrical circuit. to the electrodes when desired, 'and Ythe operators have been required to break .the electrode circuit prioito tilting the furnace. .However, the operators at times would tilt the furnace without breaking the lectrode circuit and at such time's there is anger of the' electrodes or their connections touching the cables which hold the ladle, positioned to receive `the metal, and which burns the cable and drops the ladle; v The dropping o f a .ladle having moltenme'tal therein, as is well known, generally results in serious accidents to employes.

Again, when a furnace has been emptied and is tilted back empty, the operatorsfassume that the electrode circuit has been broken and when it has. not theyhave been knownto have gotten shockedfcausing more or less serious results. With thepresent invention all of the above objectionable and serious results are eliminated, since-the electrode circuit will he automatically broken' when the furnace is tilted.

In the drawings, Figure 1 is a somewhat diagrammatic side elevation of an electric furnace of the class to which my invention pertains. Figure 2 is a wiring diagram illustrating the preferred embodimentof my inventlon.

Figures 3 and 4 are ywiring diagrams illustrating modifications of my invention.

Referrin particularly to the drawings, the numera .2 designates the body of the furnace as a whole, which `is of well known construction, and is provided with back and front ports closed by doors 3 and 4, respectively. Rockers k5 are mounted on the bottom of the body 2 and rest on the curved upper face of supporting base 6. Theyfurnace 1s adapted to be rocked or tilted by one or more cranks 7 which are secured to a shaft 8 and connected to the furnace body y2 by links 9. The shaft 8 is adapted to be rotated by a motor lOthrough gears-11 and 12. It will be understood that this invention 1s not llmited to the specific form of furnace described above, but is adapted to any form of tilting electric furnace, the form shown being used to illustrate the invention because of its simplicity.

A plurality of electrodes 14, 15 and 16 are mounted in the usual manner in the furnace body 2 and are adapted to receive electric current through the wires or cables 17, 18 and 19.

lReferring to the wiring diagram of Figure 2, the numerals 20, 21 and 22 designate the main power lines to the furnace electrodes, and the numerals 23 and 24 designate power lines leading to the tilting motor 10 and from which the control circuits are conveniently run in apparatus made as shown in the drawings.

The lines 20, 21 and 22 lead-to a main oil Y switch or interrupter 25, which is adapted lto break the circuit to the furnace electrodes Awhich are connected to the switch 25 by .means of wires 17, 18 and 19. The switch 29, the other side being connected to the positive line 24 and energizing coil 29. By energizing coil 29, the plunger 3() in the auxiliary relay is raised, making ay circuit between contact points 31 and 32, Contact 32 is connected to the positive line 24 and contact 3l is connected to the closing coil 33 .for the switch 25, the other side of the coi being connected to the negative line 28, thus energizing the coil 33 and closing the switch 25. At the same time auxiliary switch 34 closes contacts 35 and 36 and `opens contacts 37 and 38, thus placing a positive potential from line 24 on one side o red light 39, the other side being connected to the negative line 23 through fuse 40 and resistance 41,

thus Ilighting the red light 39, which form's a circuit in the'usual manner, the pushibutton 42 is closed, thus connecting points 43 and 44 and putting negative potential from line 23 on one side of'trp coil 45 for switch 25, the other side of the coil being connected tc. point :36, and'thence through switch 34 to point 37 and. positive line 2,4. The con light 47.

45 is thus energized and opens the switch 25, which breaks the circuit tothe electrodes 14, 15 and 16. At the same time, auxiliary In case of an overload on the electrode, circuit may be broken through'. the switch 25 by the overload relays 50. If the elec trode circuit exceeds a certain predetermined value, coil or coils 51 in the. over-p load relays A50 will be suliciently energized,

due to the transformers 52, to actuate contact or contacts 54, so as to cause the closing of the positive and negativelines 23y and 24 across the trip coil 45, in the same sequence as in closing the push button 42,

as described above, thus tripping the main oil vswitch 25 and opening `the electrode circuit and lighting green light 47. e

The vabove control of the electrode cir-.

cuit, it will be noted, either depends uponl the operator pushing the button 28 or upon an overload, and if the operator omits to operate the button 28 when tilting the furnace the electrode circuit will remain unbroken.

In order to positively prevent the electrode circuit remaining on during the tilting of the furnace, I have provided acontrol for said circuit,.which is coupled with? the controller for the tilting motor. ,10. A

standard controller is provided for controlling the circuit to the motor v1.0, and. it is provided with additional contacts 56,'.

57, 58 and 59, the remaining contacts, not being of necessity in the same arrangement, are not shown. ,'When the controller55 isv I position, power is applied tothe motor 10.

to move it in the desireddirection toA tilt the furnace. Assume that .the controller 55 be moved to the forward posltion,` xfnakilr'' V an.

contact between contacts 56 and 57j' vpoints 60 and 61.. When vthis contactf iis" made, negative potential 'is supplied tol point 60 from lie 23, thence'v through contacts 56 and 57 and point 61, to trip coil. 45,

from trip coil 45 to point 36,- through switch 34 to point 35 to positive line 24. The

oil switch 25 is thus trip ed and the electrede circuit broken,l an the green. light circuit. is made as explained in the manual operatlon. The same result is obtained when the controller'55 is moved to the reand 61 the this modified control a normally open limit switchf65 is secured on the base 6 of the furnace (see Figure 1) and 'serves to make the circuit through lines'66 and 67, which are the same lines closed by the contacts 56-57 and 58--59 on the'controller 55 of Figure 2. In o eration, when the furnace tilted theswltch 65 will be operated to close points 69 and 70, thus putting negative potential from supply line 23 on one side of tripfcoil 45, the other side being conynected'to 'point 36, through switch 34 to point '35, and thence to the positive line 24, thus energizing the trip coil 45 and operating the main' switch or interrupter 25. The circuit to the red light is also broken and the circuit made to the green light, as heretofore described.

Referring now to theF modified construction of Figure 4, a vnormally closed limit 4switch 69, which controls a circuit from the lines 23 and 24, is substituted for the switch 65 of Figure 3 and operaaltes to normally hold an ,auxiliary relay 70 open. The relay 70 is provided with a plunger 71gadapt'edl to close across contact points 72 andlz73 connected tok lines 66 and 67, respectively:-l` lWhen the furnace is tilted in either -direction theswitch 69 will VVbe o erated toppen the circuit to the relay 0 and, therefore, the plunger 71 will drop .closing a circuit through points J72 and 73 and wire 66 and 67 with exactly the same .'esultsaswhen they switch 65 is closed or contacts 561457 or 5S-59 are closed inthe l ,jotherfcontrols moved to either the forward orvreverse. ffi` l l *provideanvutoiatic control for breaking The. mainfeature of the invention is to thef'electrode'fcircuit when the furnace is have` specically I described cerinf embodiments. of my invention, I do snot Wight() 'be limited thereto, since various changes ,and modifications may be made without departing from the scepe ofmy invenltion as defined in the appen ed claims.

I C :e

furnaceghaving at least one electrode, landi a-sOmoe of electric currentfor said elec- 1. The combination with atilting electric trode, of means for automatically `breaking the circuit to saidv electrode when tilting said furnace.

2. The combination with a tilting electric furnace havin at least one electrode, and a source of e ectric current for said electrode, of an interrupting device controlled by an individual control circuit and adapted to interrupt the ow of electric current to said electrode, and means for automatically making said control circuit to cause said device to interrupt the circuit to said electrode when tilting said furnace.

3. The combination with a tilting electric -furnace having electrically operated tilting mechanism and at least one electrode, an a source of electric current for said electrode, of means for controlling the flow of electric current to said tilting mechanism, and an interrupting device controlled by an individual control circuit adapted to interruptthe flow of electric current to said electrode, and means controlled by said first named means for making and breaking the control circuit to said interrupting device.

4. The combination Withan electric fur nace having a furnace body mounted for tiltin about a fixed axis, means for tilting said furnace, an electric motor for operating said means, a source of electric current for said motor, at least one electrode mounted in said furnace, and a source of electric current to said electrode, of an interrupting device for interrupting the :dow of current to said electrode, and means for automatically operating said interruptor to break the flow of current to said electrode when tilting said furnace.

5. The combination with. an electric furnace having a furnace body mounted for tilting about a fixed axis, means for tilting said furnace, an electric motor for operating said means, a source of electric current for said motor, at least one electrode mounted in said furnace, and a source of electric current to said electrode, of an interrupting device for interrupting the How of current to ,said electrode, said device being operated by a separate control circuit, and a controller for controlling the flow of electricV current to said motor for tilting said furnace and for making and breakin said control circuit to said interrupting evice,

said controller being adapted to make the i control circuit to said interruptin device when moved to either its forwar or reverse position.

In testimony whereof I have hereunto signed my name.

' DAVID V. STEWART.

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