US2147070A - Variable rock furnace working - Google Patents

Description

Feb- 14, 1939- c, M. WEINHEIMER Er AL. 2,147,070

VARIABLE ROCK FURNACE WORKING Filed Jan. 16, 1935 4 Sheets-Sheet l Ef-j m Fell 14, 1939- C. M. WEINHEIMER ET AL. 2,147,070

VARIABLE ROCK FURNACE WORKING Filed Jan. 16. 1935 4 Sheets-Sheet 2 my @mi Feb. 14, 1939. Q M, WEINHElMER ET AL 2,147,070

VARIABLE ROCK FURNAGE WORKING Filed Jan. 16, 1935 4 Sheets-Sheerl 3 Feb. 14, 1939. c, M wElNHl-:xMx-:R ET AL. 2,147,070

VARIABLE ROCK FURNACE WORKING Filed Jan. 16. 1955 4 Sheets-Sheet 4 'Zag Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE VARIABLE ROCK FURNACE WORKING gan Application January 16, 1935, Serial No. 1,994

9 Claims.

The present invention relates in general to a furnace of the electric type for the melting of metals, and is more particularly concerned with improvements in the working of furnaces of the type wherein the melting chamber is rocked during the melting operation.

Heretofore, it has been common practice to melt metal in a furnace which was so arranged that the melting chamber could be rocked or oscillated l0 to cause agitation of the metal during the melting operation. Such apparatus as a rule made provision for varying the amount of rock or agitation of the metal, but the amount of agitation and its variation was left largely to the discretion of the operator, and varied with different types of metals and alloys.

We have now discovered that there are other factors, heretofore not appreciated, in the agitation of metal which is being melted which con- ?.o tribute in a large degree to the speed and eiliclency with which the metal may be melted or reduced. y

More specifically, it has been discovered that there is a direct relationship between the speed l5 or rate of melting of the metal andthe rate of increase in the amount of agitation or rocking, which if adhered to will result in the most efficient melting of the metal. That is, the metal as it begins to melt should be agitated gently and then 3G as the melting progresses, the agitation may correspondingly be increased until the maximum agitation is reached when the metal becomes completely melted.

Having the foregoing 'in mind, the present in- .'-'i vention contemplates as its primary object an improved method of melting metal, wherein advantage may be taken of our discovery to effect efficient and rapid melting of the metal.

In accordance with the general features of the invention, the rocking mechanism for practicing the steps of our invention embodies a motor driven crank shaft having eccentrically supported thereon a crank pin. This crank pin is mounted on a revolvable member which may be revolved l5 by means of a worm arrangement so that the crank pin may be disposed at variable distances from the center line of the crank shaft, whereby the throw of the crank may be altered to increase the rocking motion of the furnace. The motion of the crank pin is transmitted to a link and gear arrangement, the gearing being positively connected to the furnace shell.

Associated with the rocking mechanism is a striking lug arrangement which is in the path of a feed wheel for turning the worm a specific amount each time the crank makes a revolution. With this feature, the rock may be automatically increased from a minium value to a large value Without the necessity of control by the furnace operator. In order to terminate the rocking increase when a predetermined maximum value is reached, the striking lug is arranged to be kicked out automatically, whereby the furnace will continue to rock at a maximum angle until the rocking mechanism is shut down.

Other objects and features of this invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate a single embodiment thereof, and in which:

Figure l is a view in elevation of a furnace apparatus which may be operated according to the principles of the present invention, portions being out out to disclose details of the melting chamber shell structure;

Figure 2 is an end wew of the furnace, portions of the shell of the melting chamber being broken away to show details of the charging door;

Figure 3 is an enlarged fragmentary view having sectional portions taken substantially on line III--HI of Figure 1 to show details of the rocking mechanism;

Figure 4 is an enlarged fragmentary view partly in section and having portions of the melting chamber shell broken away to show details of the rocking mechanism, taken substantially on line IV-IV of Figure 3;

Figure 5 is an enlarged sectional view through the electrode supporting and feeding mechanism, taken substantially on line V-V of Figure i;

Figure 6 is an enlarged fragmentary section through the charging door and associated shell, taken substantially on line V-VT of Figure l;

Figure 1 is a sectional view through the driving crank of the rocking mechanism, taken substann tially on line VII-VIE of Figure 3; and

Figure 8 is a fragmentary sectional view of an alternative crank arrangement to enable reducing the rocking motion to a zero value.

Figure Q is a sectional view online IX-IX of Figure 2, to show details of the striker pin.

As shown on the drawings:

In the illustrated embodiment of the invention, there is shown in Figure l an electric furnace of the rocking type which is so arranged that the metal which is being melted may be agitated by rocking the furnace back and forth.

This furnace comprises a supporting structure which is generally indicated at l Il. This structure is provided with a plurality of wheels li which are arranged to provide a four-point rolling support for a substantially cylindrical shell I2 which defines the melting chamber. The two Wheels at the forward side of the furnace are each rotatably mounted on a spindle I3 which is secured in the supporting structure. 'I'he inner edge of each wheel is deflected to form a peripheral flange I4. The spindle I 3 is provided with a longitudinal passage I5 which is arranged so that the wheels may be pressure lubricated.

At the rear side of the shell I2, as shown in Figure 4, the Wheels II are of similar construction,l but instead of being mounted for free rotation, they are secured to a shaft I6 having its ends supported for rotation in anti-friction bearings I1-I1. At either end of the shell I2 is a rail or track I8 which engages the wheels II at -the associated end of the shell.

In the prior art devices of the herein described character, these rails were attached by brackets directly to the outer surface of the shell I2 and were subject to undesirable forces tending to cause distortion of the rails as a result of the radial expansion of the shell. In order to provide a more economical construction and overcome the foregoing objection, the shell I2 is, in this instance, closed at each end by an end member I9 which is peripherally extended and deflected to form a peripheral flange which extends over the end of the shell I2 and defines the aforementioned track or rail I8. Each end is secured in position to the shell I2 by means of a plurality of circumferentially spaced bolts 20 which are welded at their inner ends to the shell and are adapted at their outer ends for receiving securing nuts 2|. Since the end member and shell are substantially co-radial, they will expand and contract together during temperature changes whereby undesirable stresses will be substantially eliminated.

In the operation of furnaces of this character, it has been found advantageous to provide a positive connection between the shell and the rocking mechanism, rather than to depend entirely upon the frictional engagement between the driving wheels II on the shaft I6. For this purpose, one of the end members I9, in this instance the end member at the right end of the shell I2, as viewed in Figure 1, is provided at its periphery with circumferentially extending teeth 22 which dene a relatively large gear 23. The teeth of the gear 23 mesh with the teeth of a pinion 23 which is mounted on and rotatable with the driving shaft I6. It will now be evident that if the shaft I6 is rotated in one direction, the furnace shell I 2 will rotate or rock in one direction, and reverse its direction of rock when the rotation of the shaft I6 is reversed.

For oscillating the shaft I 6, a novel rocking mechanism is provided. An electric motor 25 has its driving shaft connected to suitable reduction gears contained in a gear casing 26, power being delivered through a Vdelivery-shaft 21. The outer end of the shaft 21 carries an adjustable throw crank generally indicated at 28. Ihis crank comprises a ring-shaped housing 29 having a substantially tangential cylindrical portion 30. The.

ring 29 is provided at one edge with an inwardly deflected portion defining a iiange 3l which cooperates wth a groove 32 which extends circumferentially around the peripheral surface of a worm wheel 33, whereby the worm wheel is rotatably mounted in the housing. Rotation of the worm wheel is accomplished by means of a worm 34 which meshes with the teeth of the worm wheel. 'Ihe worme34l is formed on a shaft 35 which is rotatably mounted in the cylindrical portion 30 of the housing, one end of this shaft extending to the exterior of the housing and being provided with an actuating sprocket wheel 38, the purpose of which will be subsequently more fully explained.

Outwardly disposed from the center of rotation of the worm wheel 33 is a crank pin 31. On the opposite side of the housing 29 from the location of the crank pin 31, the housing is provided with a cover 38 which is secured at its periphery to the housing 29 by means of screws 39. The housing 29 is eccentrically supported relative to the shaft 31 by means of a hub 40 which is integrally formed in the cover 38 and is secured to the shaft 21 by means of a set screw 4I.

vWith the foregoing arrangement, it will be ap- `parent that the throw of the crank may be adjusted to a large or small value by revolving the crank pin 31 by means of the worm and worm wheel about a circular path having its axis offset relative to the axis of the shaft 21. In the arrangement disclosed in Figure '1, the radius of rotation of the crank pin 31 is such that the throw of the crank may be varied from a minimum value to a maximum value, the minimum value being in this case greater than zero.

The invention, however, contemplates that there may be cases when it is desired to have the minimum throw zero-and increase the throw from zero to a maximum value. In Figure 8, an alternative arrangement is shown to meet such a requirement. In this construction, it is only necessary to choose the radius of revolution for the crank pin of such a value as to permit the crank pin axis and the shaft 21 axis to be brought into coincident relationship by actuating the worm and worm wheel. In Figure 8, the corresponding parts have been indicated by similar numerals as utilized for like parts in Figure A connecting link, generally indicated at 42. transmits the movement of the crank pin 31 to a rotatably mounted crank arm 43 which is secured to and movable with a segmental gear 3d. The teeth on this gear mesh with a pinion 45 which, together with a gear 4G, is rigidly secured to a short shaft @1 having its ends mounted in anti-friction bearings 8-d8, these bearings being suitably supported in an enclosing casing 49 and cover plate 50 therefor. The cover plate 5I) is secured to the casing by means of a plurality of screws 5I. The gear 36 meshes with a pinion 52 which is secured to one end of the shaft I5.

The amount of rocking is automatically increased from a minimum or zero value to a maximum value by progressively advancing or turning the worm 34 a predetermined amount during each revolution of the crank-pin 31. This is accomplished by means of a striker lug or pin which is disposed in the line of travel of the sprocket 38. The striker lug or pin comprises a bracket plate 53 which is secured as by bolts 54 to the frame structure. At one edge of this plate and normal to the surface thereof, there is integrally formed a tubular bore 55 within which there is mounted a piston-like member 58 which is axially slidable in the bore. A stem 51 projects outwardly from one end of the member 56 and has secured at its outermost end a cap 58 having a cylindrical body 59 which is outwardly spaced relative to the stem 51 and forms a housing for a compression spring 60 which surrounds the stem. One end of this spring bears against the closed end of the cap 58 and the other end of the spring bears against the portion of the housing forming the adjacent end of the bore 55.

The surface of the member 56 adjacent its stem end is provided with a pair of transversely extending and opposed parallel grooves 6i-8I of substantially V-shape, these grooves defining dwell points for receiving the chisel-like ends of associated detent pins 62-62 which are in each case axially forced into the associated groove by an expansion spring 63.

The member 56 is also provided with a pair of flat inclined surfaces 63 which extend away from the grooves 6|-6I and converge towards the opposite end of the member 56 to form a contracted portion defining the dwells 64-64, the purpose of which will subsequently be evident.

This latter end of the member 56 is extended to form a web portion 65 having its outer end rounded as shown at 66. One side of this web carries a normally disposed rib 61 which extends longitudinally along the web. The other side of the web, as shown in Figure 9, is provided with a similarly disposed rib 61 which projects outwardly from the web an amount slightly greater than that of the rib 61.

With the rib 61 disposed as shown in Figure 3, it will engage the teeth on the sprocket wheel 36 each time the crank is revolved, and will advance the sprocket wheel, for example, one tooth during each revolution of the crank. The angle of rock will therefore be slowly increased in steps until a maximum angle is reached, at which time the pivotal connection of the link 42 to the crank pin 31 will strike the curved end 66 of the web 65 and move the member 56- to the right, thereby disengaging the detent pins 62 from the grooves 6|6i. The spring 60 continues to force the member 56 outwardly until the detent pins 62-62 come to rest in the dwells 64-64.

Should it be desired to advance the rocking angle more rapidly, the cap 58 is rotated through an angle of 180 degrees, which action will bring the rib 61' into the position formerly occupied by the rib 61. Since the rib 61' projects a greater amount than the rib 61, it will engage the sprocket wheel one tooth ahead of the position engaged by the rib 61 and will therefore advance the sprocket wheel two teeth each time the crank makes one revolution. It will be obvious that when the maximum rocking anglel is reached and the striking pin has been kicked out, the furnace will continue to rock at the maximum angle until the rocking mechanism has been shut down.

Referring to Figures 1 and 6, it will be observed that the furnace shell I 2 is provided with a charging and pouring door which comprises an oval-shaped frame member 68 which is secured to the shell l2 by means of a plurality of bolts 68. The charging door comprises an oval-shaped plate having hook hinge lugs 1l-1I at its upper edge which cooperate with hinge pivot members 12-12 on the frame 68. The charging door, being thus hinged, may be swung upwardly by means of a handle 13 adjacent its hinged upper edge and easily removed, when desired.

As shown in Figure 6, the charging door has a lining of refractory material 14 on its rear surface, this lining being secured to the door proper by means of suitable bolt and nut connections 15-15. The charging door may be clamped in closed position by means of a pair of laterally positioned screws 16-16 which are each threaded into a yoke 11 having its end portions pivoted at 18 for swinging movement. During the clamping operation, the screws 16 respectively engage laterally extending lugs 19 which are integrally formed with the door. When it is desired to open the door, the screws 16 may be loosened and the yoke 11 swung outwardly so as to'release the lug portions 19 and enable the door to be swung open or removed.

Referring to Figures 1 and 2, it will be observed that the lower edge of the door 10 is provided with an arcuate cut-out portion 80 which cooperates with a metallic member 8|, this latter member being s'o shaped as to form a pouring spout which is lined with clay in a manner well known in the art.

In order that the metal, when being poured, may be kept out of contact with the air during its movement from the furnace to the ladle or mold, a tubular conductor 82 is supported by a suitable bracket 83 with one end secured in the pouring opening below the door proper. The use of the pouring conductor just described prevents oxidation of the metal during the pouring operation. In order that further controi of the atmospheric conditions surrounding the melting or reduction of the metal may be effected, the furnace shell is provided with an opening as shown at 84, this opening being adapted in any well known manner for making a flexible pipe connection thereto. It is preferred that this opening be disposed within the angie subtending the arc oi' the shell occupied by the charging door, so that this opening will not be washed by the molten metal during the rocking operation.

By connecting a flexible pipe and using suitable valve controls, it is possible to conduct carbon monoxide, carbon dioxide, or other fluid mediums into the furnace shell, and thus controi the reducing atmosphere during the melting and pouring operations.

In the herein described embodiment of the invention, it is proposed to manually shift the furnace during the pouring of the molten metal. This is accomplished by providing a socket member 85 on one of the end members of the shell lil, the socket member being adapted to receive therein a removable lever 86 by means of which the shell may be manually rotated to such posi-n tion as to permit the molten metal to ow through the tubular conductor 82. This manual pouring would necessitate a reversal of the operation of the rocking mechanism, and since it would be impracticable to reverse the gears, etc., it has been found desirable to provide means for disconnecting the major portion of the rocking mechanism during the pouring operation.

The foregoing is accomplished by making the connecting link 42 in two parts, namely, a tubular sheath 81 which is fixedly secured as by a pin 88 to a pivot bearing 89 which is associated with the crank 43, and a shaft member 90 which is slidable within the sheath 81 and is connected at one end to a pivot bearing 9i which is associated with the crank pin 31. The tubular sheath 81 and shaft 90 are normally locked together by means of a manually operable spring actuated lock comprising a cylindrical member 92 which extends normally to and is fixedly secured to the sheath 81.

Within the tubular member 92 there is mounted for reciprocable movement a pin or plug member 93 having a tapered end portion 94 which is adapted to extend through an opening in the sheath 81 into an opening 95 in the shaft 90. For

actuating the pin 93, a stem 961s secured thereto, this stem extending through a plug 91 in the open end of the tubular member 92 and having at its upper end a button 98 which may be grasped by the operators fingers and pulled upwardly to free the sheath 81 and shaft 90 for relative axial movement. The latching pin 93 is normally forced in' a downward direction by means of a compression spring 99', one end of which bears against the pin 93 and the other end against the plug or bushing 91.

It will therefore be evident from the foregoing description that if the latch just described is released by pulling up on` the same, the operator may by means of the lever 86 rotate the furnace to the pouring position. This movement of the furnace will likewise cause a movement of the crank arm 43 and will cause the connecting link 42 to be telescopically elongated, without the necessity of having to rotate the crank pin 31 and its connections to the motor mechanism. As soon as the pouring operation is completed and the furnace is rotated in the opposite direction the latch plug will automatically engage the shaft 90 and re-establish a rigid link connection between the crank pin 31 and the crank arm 03.

A pair of electrodes are supported on the end members of the furnace shell, the axes of the electrodes being coincident with the shell axis. Each electrode is provided with its individual feeding mechanism which permits the electrode to be axially fed into the melting chamber.

Referring to Figure 1, it will be seen that the associated end member |9 is provided with an outwardly extending ring flange for receiving therethrough an electrode |0|, suitable bushing members |02 and |03 being disposed between the electrode and the flange |00, whereby the electrode is insulated relative to the furnace shell structure.

The electrode supporting and feeding mechanism comprises a U-shaped bracket generally indica-ted by the numeral |04. The spaced legs of this bracket |05 and |06, respectively, are outwardly deflected at |01 and |08 to form securing feet or lugs which are secured to the associated end member I9 as by securing bolts |09. Adjacent the feet |01 and |08, the spaced legs of the bracket are interconnected by a bridging member i0 which not only braces the legs of the bracket but also serves as an inner bearing for an upper guide rail and a combination lower guide and screw |I2, the outer ends of these guide members being rotatably supported in the closed end of the bracket. Actuation of the combined guide and screw ||2 is accomplished by means of a suitable hand wheel M3.

Associated with the guide rail is a guide block H, and with the guide screw ||2 a nut block l5. The blocks l i0 and I5 are clampingly secured as by through bolts I6 to a hollow clamping member H1, the blocks in each case being insulated from this member ||1 by means of insulating members ||8 and H9, respectively. One face of the hollow clamping member ||1 is provided with an inwardly deflected portion del ning a semi-circular surface for engaging with the electrode. Cooperatively associated with the clamping member |1 is a hinged clamping member |2| which is pivoted at |22 to the block ||1 and is provided with a recessed portion |23 which defines a semi-circular surface for engaging the electrode. The upper edge of the clamping member |2| is provided with an open-ended slot |24 for receiving therein a hinged bolt |25 that is pivoted at its inner end 26 for swinging move` ment and threaded for cooperation with a hand nut |21.

'I'he hollow clamping member ||1 is provided with threaded lateral openings |28 and |29 for connection to suitable iiuid inlet and outlet connection, whereby a cooling uid may be circulated through the hollow clamping member. The rear wall of the hollow clamping member is provided with an integrally formed extension |30 having a right angled flange portion |30' with a plurality of holes |3| therethrough to facilitate the bolting of electric power supply cables to the hollow clamping member. The closed end of the bracket |04 has secured thereto a plate member |3| by means of bolts |32, which is adapted to support an insulated guide bushing |33 for receiving therethrough the electrical power supply cables.

With reference to the manner in which the power supply cables and water connections were brought to the electrode clamps in the prior art devices of the herein described invention, it was customary to carry the cables in a loop from a stationary bus bar at the back of the furnace to the guide bushing |33 and also provide a loop between the guide bushing and the connection at the electrode. This arrangement proved objectionable in that the cables were subjected to bending forces during the rocking of the furnace and were subject to breakage at the point where they passed through the guide bushing.

Ihe foregoing objections and diiculties have been overcome by the arrangement shown in Figure 1, wherein the cables and fluid connections at each end of the furnace are held stationary at a point near the axis of rocking and are carried in a relatively short single loop to the guide bushing at that end so that the effect of the rocking movement of the furnace on the cables and i'luid connections is absorbed by a twisting rather than a bending motion.

As disclosed, the electric power supply cables |36 are carried through a suitable conduit |35 to a junction or outlet box |33 which is supported at or near the rocking axis of the furnace. .Cooling fluid supply and return pipes |31 and |38 respectively are provided adjacent the outlet box and hose connections |39 and |40 carried through suitable openings into the junction box |36, a suitable control valve IM being placed in the supply pipe. From the junction box the cables and hose connections are grouped by a rubber band or the like |02 and carried in a loop to the guide bushing |33, and thence to the electrode clamp where appropriate connections are made, as hereinbefore described.

Referring to Figure 2, it will be noted that the electrode bracket |00 is oiset relative to the diameter of the furnace shell and is disposed on the opposite side of this diameter from the location of the charging door. With this arrangement, the weight of the charging door and its tendency to rotate the furnace during the pouring operation is counterbalanced.

In operation, the means embodied in the herein described invention for varying the angle of rock operation has proved to be very desirable in a furnace of this type.

The advantages of this method of operation will become more evident from a brief consideration of the melting operation.

In a furnace of the herein described type, it is desirable to wash the refractory with molten metal in order to keep the temperature of the refractory relatively low and, moreover, due to the heat absorbed by the molten charge from the refractory during the rocking operation, it is desirable to decrease the rate at which the metal is heated, thereby reducing the electrical operating costs.

It will be apparent that full rocking cannot immediately be employed as soon as the furnace is started, since the tumbling action of the solid pieces composing the charge might injure the electrodes and possibly the refractory. Moreover, with the charge in solid form, the transfer of heat from the hot refractory to the charge would be relatively low due to the small contact area between the charge pieces and the refractory.

As the heating proceeds, some of the charge pieces will be melted and fall through the interstices of the other pieces to the bottom of the melting chamber. This molten metal may be washed back and forth through a small arc, but should not be agitated too vigorously since by doing so the remaining solid pieces might injure the refractory or electrodes.

The variable rock feature of the present invention is therefore decidedly advantageous in that it permits the angle of rock to be increased at substantially the same rate as the metal is being melted down below the electrodes.

The striker lug as previously described may be set to automatically advance the rocking angle in a relatively slow or rapid manner, as desired. This feature enables adjustment of the rate of increase of the rocking angle for metals having different melting rates. For example, brass melting would require a faster rate of increase in the rocking angle than would iron.

From the foregoing description it will be apparent that the hereindescribed invention provides an improved method for the melting of metal, wherein the amount of agitation of the metal is varied as a function of the rate of increase of the melted metal, the agitation being such as to gently agitate the metal as it begins to melt, and-thereafter being increased to a maximum as the rate of melting increases, a maximum of agitation being reached when the metal becomes completely melted, whereby the metal is more eiiiciently and rapidly melted.

Now, of course, it is to be understood that while the invention is illustrated and described in detail in its preferred form, the invention is not to be thus limited but only insofar as defined by the scope and spirit of the appended claims.

We claim as our invention:

1. The method of melting a metal in a furnace of the rocking type which consists in increasing the amount of rock at substantially the same rate as the rate at which the metal therein is being melted.

2. The method of melting a metal in a furnace of the rocking type which consists in varying the amount of rock as a function of the speed at which the metal is melted.

3. The method of melting a metal which consists in agitating the metal to be melted, and the varying of the amount of agitation as a function of the rate of increase of the melted metal.

4. The method of melting metal in a furnace which comprises heating the metal to a melting temperature, gently agitating the metal as it begins to melt, and then increasing the amount of said agitation as the melting of the metal continues.

5. The method of melting metal in a furnace which comprises heating a quantity of metal to a melting temperature, gently agitating the metal as it begins to melt, and then increasing the agitation at such rate as to substantially reach a maximum when all the metal is melted.

6. The method of melting a quantity of metal in a furnace which consists in increasingly agitating the metal as a function of the time required to completely melt the metal.

7. The method of melting a quantity of metal in a furnace which comprises agitating the metal during the melting operations, and increasingly varying said agitation at a rate dependent upon the time required to completely melt the metal.

8. The method of melting metal in an electrode type furnace which comprises initially subjecting the metal to rocking movements of relatively small amplitude, whereby damage to the electrode by unmelted metal striking the same is prevented, and thereafter increasing the amplitude of rocking movement, when a sufficient amount o! metal has melted to prevent unmelted metal striking the electrode.

9. The method of melting metal in a furnace which comprises agitating the melted metal to cause it to wash the unmelted metal during the melting operation, and increasingly varying the amount of agitation of the melted metal, as the melting of the metal progresses, in accordance withfthe rate at which said metal is being melted.

CLAUDE M all miauw FRANK P. WEAVER. LEON V. PITI'MAN.

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