US3371140A

US3371140A - Optical system for electric arc furnaces

Info

Publication number: US3371140A
Application number: US409661A
Authority: US
Inventors: Peter J Wynne
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1964-11-09
Filing date: 1964-11-09
Publication date: 1968-02-27
Anticipated expiration: 1985-02-27
Also published as: BE665692A; GB1093650A; FR1444984A; NL6510256A; DE1483122A1; DE1483122B2

Description

mum HEBERUWK. oLHnun nu| Feb. 27, 1968 P. J. WYNNE OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES 3 Sheets-Sheet 1 Filed Nov. 9, 1964 INVENTOR. Peter J ZZ flne Feb. 27, 1968 P. J. WYNNE OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES Filed Nov. 9, 1964 5 Sheets-Sheet 2 Feb. 27, 1968 P. J. WYNNE OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES 5 Sheets-Sheet Filed Nov. 9, 1964 INVENTOR. Peter J Z/yzme fittarmgy United States Patent 3,371,140 OPTICAL SYSTEM FOR ELECTRIC ARC FURNACES Peter J. Wynne, Pittsburgh, Pa., assignor to McGraw- Edison Company, Milwaukee, Wis., a corporation of Delaware Filed Nov. 9, 1964, SeraNo. 409,661 15 Claims. (Cl. 13-9) This invention relates to optical systems for electric arc furnaces and, more particularly, to an optical system for a controlled atmosphere consumable electrode type electric arc furnace.

Consumable electrode electric arc furnaces have been widely used for such applications as the melting of refractory metals, of which titanium is an example. Such furnaces, in general, include a sealed chamber wherein a consumable electrode is progressively melted under a controlled atmosphere and the resulting molten metal collected in a crucible to form an ingot. Melting is accomplished by means of an are which is drawn between the consumable electrode and the ingot, and which is sustained by relatively large direct currents. As the ingot forms, the electrode length gradually decreases so that it must be lowered in order to maintain the proper arc length for the desired melting conditions. For this purpose, a motor-driven electrode ram is provided for feeding the electrode toward the ingot, in accordance with the electrical conditions in the arc. After the electrode has been completely consumed, the ingot must first be allowed to cool and then be removed from the crucible prior to the initiation of another melting operation. Because a relatively long time is required for such ingots to cool, it is desirable that a single electrode drive and ram assembly be mounted for successive operation over several crucibles.

In most melting applications, it is necessary to observe the are at various times during a melting operation. For this reason, most prior art controlled atmosphere, consumable electrode arc furnaces were provided with fixed sight tubes for viewingalong the electrode and in the gap between the electrodeand the crucible. Prior art sight tubes were not wholly satisfactory, however, because the gap between the electrode and the crucible varies consider ably even where the electrodes are nominally of the same size. This is additionally complicated by the fact that consumable electrodes employed in this type of furnace are generally in the order of twelve feet in length and may have surface irregularities. Prior art sight tubes were additionally unsatisfactory Where various size electrodes were employed, because they could not penetrate sulficiently close to the electrode ram to view along the surface of smaller-sized electrodes.

In controlled atmosphere, consumable electrode vacuum arc furnace installations, the arc image is generally pro jected on an operator viewing screen. Prior art optical systems could not be employed, however, in installations having a single electrode drive assembly and a plurality of crucibles.

It is an object of the invention to provide a new and improved optical assembly for controlled atmosphere, consumable electrode, electric arc furnaces.

A further object of the invention is to provide an optical assembly capable of viewing along the gap between the electrode and the crucible of controlled atmosphere, consumable electrode, arc furnaces regardless of electrode size and surface irregularities.

Another object of the invention is to provide an optical system for use with consumable electrode arc furnaces having a single electrode drive assembly and a plurality of spaced apart crucibles.

A still further object of the invention is to provide an arc melting furnace having a plurality of vessels, elec I 3,371,140 Patented Febo 27,, 1968 ice trode means for being selectively positioned over the vessels and an optical system having a first light modify= ing means mounted on the electrode means for receiv= ing the arc image ray and for projecting the same to viewing means when the electrode means is over one vessel and second light modifying means for receiving the projected ray and for transmitting the same to the view= ing means when the electrode means is over a second vessel.

Yet another object of the invention is to provide in an electric arc furnace an optical assembly rotatably mounted about an axis generally parallel with the electrode and including tube means disposed at a predetermined angle relative to the axis of rotation and having first light modi= fyirig means for redirecting arc image rays along the axis of the tube means and fixedly mounted second light modi= fying means for receiving the projected rays and for re= directing them at a preselected angle.

These and other objects and advantages of the instant invention will become more apparent from the detailed description thereof taken with the accompanying draw= ings in which:

FIG. 1 is a side elevational view, partly in section, of a controlled atmosphere, consumable electrode, electric arc furnace which incorporates the optical assembly accord= ing to the instant invention;

FIG. 2 is a side elevational view, partly in section, of a portion of the optical assembly illustrated in FIG. 1;

FIG. 3 is a view taken along lines 33 of FIG. 2;

FIGS. 4 and 5 are respectively a top plan view and a side elevational view schematically illustrating the op-= eration of optical system according to the instant inven-= tion, and

FIG. 6 is a perspective view of another portion of the optical system illustrated in FIG. 1.

Referring now to the drawings in greater detail, FIG. 1 shows a consumable electrode, controlled atmosphere, electric arc furnace designated by the reference numeral 10 and having a crucible section 11, a middle section 12 and an electrode drive assembly 13.

The crucible section 11 includes an outer, substantially cylindrical shell 15 having a bottom closure member 16 which is suitably afiixed thereto in a sealed relation to provide a cooling jacket for a crucible 22 disposed therein and which receives an ingot 23 formed from the metal being melted. Cooling fluid is supplied to the shell 15 through inlet and outlet pipes 24 and 25, respectively. A horizontal base plate 26 is supported adjacentthe upper end of shell 15 by vertical columns 28 and has a central aperture 29 for receiving the upper end of the crucible 22. A gasketed flange 32 extends outwardly from the upper end of the crucible 22 and is suitably afiixed to the upper surface of the mounting plate 26.

The middle section 12 of the furnace 10 includes a lower middle section 36, an upper middle section 37 and an upper middle section drive assembly 38. The lower middle section 36 has a generally cylindrical configuration which is cordial with the crucible 22. An outwardly extending flange 39 at the lower end of lower middle sec tion 36 is suitably aflixed to the flange 32 on crucible 22.

The upper middle section 37 which is an inverted, cup= shaped member forms a closure for the hollow assembly 45 consisting of the crucible 22, the lower middle section 36 and the upper middle section 37., A suitably gasketed flange 41 extends outwardly from the lower end of the upper middle section 37 and is releasably securable to a. corresponding flange 42 on the upper end of the lower middle section 36 by means of bolts 43.

An electrode 46 is disposed within the hollow assembly 45 and has a stub 48 integrally formed at its upper end for releasable attachment to the bottom of a hollow elec= trode ram 49 by a clamp 50. The ram 49 slidably passes through a sealing bushing 56 which provides a fluid-tight seal for the enclosure 45 and, in addition, electrically insulates ram 49 from the upper middle section 37.

A pipe 57 is connected to and communicates with the interior of the enclosure 45 for placing the latter in communication with an evacuator or source of inert gas it a partial vacuum or inert gas atmosphere is required during the melting operation.

A. generally rectangular base plate 60 is disposed above the upper middle section 37 and is mounted on the upper ends of first and second frame members 61 and 64, respectively. The lower end of member 61 is supported in a pair of wheels 62, which engage the upper surface of the plate 26 and the lower end of the second frame member 64 engages a rotary hydraulic cylinder 63 whose pur pose will be explained in greater detail hereinbelow. The plate 60 supports the upper middle section drive assembly 38 and the electrode drive assembly 13.

The electrode drive assembly 13 is supported above the base plate 60 by vertically extending rods 65 whose iower ends are aflixed to the plate 60 and whose upper ends support a top plate 66. The drive assembly 13 also includes a first plate 68 which is affixed to the upper end of the electrode ram 49 and a second plate 70 disposed vertically above the plate 66 and having a nut 71 affixed in an aperture formed therein and concentric with the ram 49. A tubular member 74 is slidably disposed on each of the support rods 65 and each is aflixed at its lower end to the first plate 68 and at its upper end to the second plate 70 so that the plates 68 and 70 are coupled for sliding vertical movement on the support rod 65.

The electrode drive assembly 13 also includes a motor 76 suitably mounted on the upper plate 66 and a drive screw 77 which threadably engages the fixed nut 71 in the second plate 70 and extends vertically downward through apertures 78 and 80 in the plates 66 and 68, re-= spectively, and into the hollow interior of the electrode ram 49. A pinion 81 is carried on the output shaft 82 of: the motor 76 and engages a gear 84 affixed to the upper end of the screw shaft 77 and rotatably mounted about the aperture 78 in the plate 66 by a suitable bearing assembly 85.

Electrical energy is supplied to the electrode 46 through a terminal 88 mounted on plate 68 and which is constructed and arranged to receive a flexible conductor 89. Current flows from the plate 68 through the electrode ram 49, the clamp 50, the stub 48 and to the electrode 46. Bushings 90, of any suitable insulating material, insulate the guide rods 65 from the plates 68 and 70 and the tubes 74.

The upper middle section drive assembly includes a motor 92 suitably mounted on the base plate 60 and a pinion 93 afi'ixed to the motor output shaft 94. Pinion 93 engages a ring gear 96 which is rotatably mounted by means of a bearing (not shown) on a bushing 98 disposed in an aperture 100 formed in the support plate 60. The bushing 98 slidably receives the electrode ram 49 and electrically insulates it from the base plate 60. Three small gears 102 engage the ring gear 96 at approximately 120 intervals and each is rotatably mounted in bearings 105 disposed in corresponding apertures 104 formed in the plate 60. Each of the small gears 102 has a suitable internal threaded aperture for engaging the upper end of a screw shaft 108, the lower end of which is coupled to the upper surface of the upper middle section 37 by a universal coupling 110.

The electrode drive assembly motor 76 may be of the reversible, variable speed, DC type, which is controlled in accordance with electrode voltage and current conditions. The motor control, which is not shown but is well known in the art, causes the motor 76 to rotate in a direction which maintains the are between the electrode 46 and the ingot 23 at a relatively uniform length. Thus, when the arc length is too short, the motor will rotate the screw shaft 77 in a first direction through the pinion 81 and the gear 84. This moves the nut 7.1, and the plate 70 to which it is affixed upwardly relative to the shaft 77. The electrode ram 49 which is rigidly coupled to the plate 70 by the plate 68 and the tubes 74 also moves upwardly to raise the electrode 46. Conversely, when the arc length is too long the motor 76 will rotate the shaft 77 in an opposite direction to lower the electrode 46. However, since the electrode 46 has a smaller diameter than the crucible 22, "the general direction of movement of the electrode will be downward during a melting operation.

After the electrode 46 has been melted so that substan= tially only the stub 48 remains. the electrode drive as sembly 13 is positioned above the alternate crucible 22 while the ingot 23 is allowed to cool. For this purpose. the motor 76 is driven in a direction which raises the clamp 50 to its uppermost position in the chamber 45. The bolts 43 are then removed to release the upper middle section 37 from the lower middle section 36. Motor 92 is then operated to rotate the gears 102 through the agen cy of the pinion 93 and the ring gear 96 in a direction which raises each of the screw shafts 108. As a result, the upper middle section 37 is raised to a position. free of the lower middle section 36. The motor 76 is then reactuated in a direction which raises electrode clamp 50 and the stub 48 to a position above the upper flange 41 of the lower middle section 36. The rotary hydraulic cylinder is then actuated to pivot the base plate 60 and the frame member 61 and 64 to a position above an alternate crucible as the wheels 62 roll on the base plate 26. After the electrode drive assembly 13 has been positioned above the alternate crucible 22, the electrode ram assembly 49 is lowered until the clamp 50 is in a position to be secured to the stub on the electrode which was previously disposed within said alternate crucible. The motor 92 is then operated in a direction which lowers the upper middle section 37 until it is in a position to be secured to the flange on the lower middle section of the alternate crucible 22', whereby melting may begin in said alternate crucible while the ingot 23 in the first crucible 22 cools.

The optical system, according to the instant invention, is shown in FIGS. 1, 4 and 5 to include a pair of optical assemblies 120, one of which is mounted on each of the opposite sides of the upper surface of the upper middle section 37 and adjacent the opposite sides of the bushing 56. The optical system also includes a mirror assembly 121, a first lens 122 and a second lens 123 associated with each of the optical assemblies 120. 'Each of the optical. assemblies along with its associated mirror assembly 121, first lens 122 and second lens 123 transmits an image of the are at its side of the electrode to an operator viewing screen 124.

The optical assembly 120 is shown in FIG. 2 to be mounted in an aperture 129 formed in the upper end of the upper middle section 37 and adjacent the bushing 98 by means of a plurality of clamping blocks 130 and screws 131, only one set of which is seen in FIG. 2. The clamping blocks 130 engage the upper surface of an optical assem= bly base plate 133 to force an outer peripheral flange 134 on said plate against a shoulder 136 formed in. the periphcry of the aperture 129.

The optical assembly 120 is shown to include a first mirror 138, a second mirror 139, a lens 140 and a reflect.- ing prism 142. The lens 140 is disposed at the junction of a pair of hollow, open-ended coaxi-ally' disposed and C0-- radial mirror support tubes 144 and 145. One end of each of the tubes 144 and 145 is cut at a substantially 45 angle and is recessed for receiving one of the

mirrors

138 and 139, respectively. The

mirrors

138 and 139 are held in position by means of mirror support plates 147, which are suitably afiixed to the remote ends of each of the tubes 144 and 145.

A bottom aperture 148 is formed in the end of the tube 144 and opposite the mirror 138 to permit the passage of the arc image rays 125 from the crucible 22 disposeiig It will be appreciated that rotation of the pinion by means of the hand knob 179 will cause the tube 156 therebelow. The first mirror 138 redirects the rays 125 in a direction parallel to the axis of the tubes 144 and 145 through the lens 140 and onto the mirror 139 which, in

' tube 144.

The aperture 150 adjacent the mirror 139 is recessed at 155 for receiving the lower end of a vertical tube 156 to which the mirror support tube 145 is suitably aflixed in a sealing relation. The bore 158 of the tube 156 is coaxial with the opening 150 to permit the passage of the arc image rays 125 from the mirror 139 to the prism 142. The vertical tube 156 extends through an aperture 160 in the base plate 133 and terminates at its upper end in an outwardly extending flange 161. The lower surface of the flange 161'is suppor:ed by an annular bearing ring 163 which surrounds the tube 156 and is disposed in a circular recess 164 formed in the upper surface of the base plate 133. A collar 166 surrounds the tube 156 below the base plate 133 and is held in positionby a set screw 167 to prevent upward movement of the tube 156 relative to the I base plate 133.

- for rotation in an aperture 174 formed in the upper surface of the base plate 133 and which extends upwardly through an aligned aperture 175 forined in an inverted L-shaped pinion holder 177 suitably aflixed to the base plate 133. A hand knob 179 is aflixe d to the upper end otthe sh'aft172 so that the pinion 171 may be rotated in either direction.

A cover glass 180 is secured over the upper end of the tube 156 by a glass cap 182 which is aflixed tothe flange 161 by screws 184'and' which has an aperture 183 coaxialwith the axis of the tube 156.

The prism 142 which is of the total reflecting type is secured to a prism mount 186 by aprism frame 187. The prism mount 186 has a central aperture 189, which is fixedly positioned above the bore of the tube 156 by a prism support bracket 190 rigidly aflixed to the base plate to rotate about its axis. This, in turn, will move the mirror 138 and the opening 148 in the tube 144 in a circular path about the axis of tube 156, as indicated by phantom lines in FIG. 2. This allows the mirror 138 to be moved relative to the inner surface of the crucible as, for example, between the position shown by full lines in FIG. 4 to the position shown by dotted lines. In this manner, the mirror may be placed in a position as close as possible to the electrodesouter surface to view the arc, taking into consideration discontinuities in the electrodes outer surface. In addition, when a smaller diameter electrode 46' is employed'as shown by phantom lines in FIG. 4 the mirror 138 may be rotated into a correspondingly close position relative to such an electrode. Regardless of the position of the mirror 138, however, it will'always face the mirror 139 so that the electrode image ray 125 I 12.1 and the mirror assembly 122 associated with each of 6 the optical assemblies 120, is mounted on a horizontal plate 194, which is supported on the-member 64 by a bracket 195. Support member 64 is suitably apertured at 197 to permit the arc image ray.125 to pass front the plrisms 142 to their associated lens 122 and mirrors assentb y 121.

As seen in FIGS. 4 and 5, the arc image rays from each side of the electrode pass upwardly to the first mirror 138 where they are reflected backwardlyonto the second mirror 139, for redirection upwardly to the prism 142, which in turn reflects them through their associated .lens 122 and mirror assembly 121 and then through the lens 123 to the operator viewing screen 124.

Each mirror assembly 121 is shown more particularly in FIG, 6 to include a three sided housing 200 having

side walls

202 and 203 and a back wall 206 which is pivotally mounted between an open position shown in FIG. 6 and a closed position. The

sidewalls

202 and 203 of housing 200 are preferably of substantially equal areas and each has an enlarged aperture 205 formed therein.

sembly. 13 pivots, which is 90 in the illustrated embodiment. The backwall is equiangularly disposed relative to each of the

sidewalls

202 and 203 and this angle is 45 in the illustrated embodiment.

A mirror 207 is atfixed to the inner surface of the closure cover 206. It will be appreciated that when the backwall 206 is open, light rays entering either of the apertures 205 will pass out of the openback of the housing 200. However, when the back wall 206 is in a closed position, light rays entering one of the apertures 205 J tion over the first crucible 22, as shown by full lines inFIG. 4, each of the openings 204 and prisms 142 are also in' alignment with its respective lens 123. However,

when the electrode drive assembly 13 is pivotcdto its" position over the alternate crucible 22', as shown by.-

phantom lines in FIG. 4,v the optical center line of each prism and opening 204 is displaced from that of their associated lens 123 by an angle equal to the .angle through which the drive-assembly'13 pivots. For this reason, the arc image rays must be redirected through an angle equal to the complement of the pivoted angle. This result is achievedby the angular arrangement of the walls 202,

.203 and 206 of the housing 200.

When the electrode drive assembly 13, which-carries the optical assemblies 120, is in a position over thefirst crucible 22, each of the backwalls 206 of the housings 200 is open so that the arc image rays 125 pass through the openings 204 and out of the open backs of the housings 200 to the lens 123 and the operator viewing screen 124. However, when the electrode drive assembly is pivoted to a position above the alternate crucible 22', as shown by phantom lines in FIG. 4, the backwalls 206 of the housings 200 are closed, so that the mirror 121 is opposite the apertures 204 and 205. When in this position, aperture 204 is in alignment with the prism 142 while aperture 205 is in alignment with the lens 123. As a result, the are image rays from the prisms 142 will enter the 7 metrically opposite sides of the pivotal axis and lie along a line angularly displaced relative to the arc image rays E35 by an angle which is one-half of the complement of the pivotal angle. In the illustrated embodiment the assembly illustrated pivots 90 so that the minor astcntblics lie along a line displaced 45 from the arc image rays 125.

it will be seen that the optical system according to the instant invention permits the arc to be viewed on a. single ttttor viewing screen even when the electrode drive mbly is pivoted from a position over a first crucible .2 to a position over a second, or alternate, crucible 22'.

It will also be appreciated that if the pivotal angle of the electrode drive assembly is other than 90, the angles between the

walls

202 and 203 and the closure 206 of the housing 200 will have to be adjusted accordingly.

While only a single embodiment of the instant invention has been shown and described, it is not intended to be limited thereby but only by the scope of the appended claims.

i claim:

1. In an arc melting furnace, the combination of a plurality of vessels, support means, electrode drive means mounted on said support means for supporting an electr do in said vessels, said support means being movable from a fi'st position above one of said vessels'to a second position above another of said vessels, an optical system including light modifying means mounted on said electrode drive means and constructed and arranged to receive an electric arc image ray and to project said ray at a -edetermined angle, viewing means disposed for reing said projected ray when said electrode drive mechanism is in its first position, reflecting means positioned to receive said projected rays when said electrode drive mechanism is in its second position, said reflector =ing disposed in such an angular position relative to said t modifying means and said viewing means that'the projected rays will reflected to said viewing means.

in an arc melting furnace, the combination of a piurality of vessels each adapted to receive an ingot ned by the melting of a consumable electrode therein, ure means selectively engageable with the upper ends of said vessels, an electrode drive mechanism extending through said closure means for supporting an electrode in said vessels, and means for moving said electrode drive mechanism from a first position above one of said vessels to a second position above another of said vessels, an optical system including light modifying means mounted on'said electrode drive means and constructed and arranged to receive an electric arc image ray and to 'ect said ray at a predetermined angle, viewing means sed for receiving said projected ray when said elec- "cirdrive mechanism is in its first position, reflecting us mounted on said electrode drive mechanism and tioned to receive said projected rays when said elecitutlt. drive mechanism is in its second position, said t".;llt?ClOI being disposed in such an angular position relative to said light modifying means and said viewing means that the projected rays will be reflected onto said viewing Ill iiS.

. In an arc melting furnace, the combination of a g inrality of vessels, support means, an electrode drive in its first position, reflecting means mounted on said sctrode drive mechanism and being movable therewith,

aid reflecting means being positioned to receive said pro- 1 .d rays when said electrode drive mechanism is in mounted on said means for supporting an electrode in each of its first and second positions, said reflecting means also being movable relative to said drive mechanism between an operative position which is effective to reflect .said rays and an inoperative position in which it s ineffective to reflect said rays, said reflector being disposed in such an angular position relative to said light modifying means and said viewing means that the projected rays will be reflected at an angle which is a complement of the angle through which said electrode drive mechanism pivots from its first to its second positions.

t. In an arc melting furnace, the combination of a plurality of vessels, support means, an electrode drive mechanism mounted on said support means for supporting an electrode in said vessels, said support means being movable from a first position-above one of said vessels to a second position above another of said vessels, an optical system including light modifying means mounted on said electrode drive means and constructed and arranged to receive an electric arc image ray and to project said ray at a predetermined angle, viewing means disposed for receiving said projected ray when said electrode drive mechanism is in its first position, reflecting means pivotally mounted on said support means and being movable therewith, said reflecting means being positioned to receive said projected rays when said support means is in each of its first and second positions, said reflecting means also being movable relative to said support means between an operative position which is effective to reflect said rays and an inoperative position in which it is ineffective to reflect said rays, said reflecting means being disposed in such an angular position relative to said light modifying means and said viewing means when said electrode drive mechanism is in its second position that the projected rays will be reflected to said viewing means.

5. In an arc melting furnace, the combination of a plurality of vessels each adapted to receive an ingot formed by the melting of a consumable electrode therein, frame means constructed and arranged to be moved horizontally from a first position above one vessel to a second position above another vessel, closure means carried by said frame means and selectively engageable with the upperends of said vessels, an electrode drive assembly mounted on said frame means and extending through said closure means for supporting an electrode in said vessels, an optical system including light modifying means mounted on said frame means and constructed and arranged to receive an upwardly directed electric arc image ray and to project said ray at a predetermined generally horizontal direction, viewing means disposed for receivingv said projected ray when said frame means is in its first position, reflecting means pivotally mounted on said frame means and being movable therewith, said reflecting means being positioned between said light modifying means and said viewing means when said electrode drive mechanism is in its first position, said reflecting means being pivotable relative to said frame means between an operative position in which it is effective to reflect said rays and an inoperative position in which it is ineffective to reflect said rays, said reflector being disposed in such an angular position relative to said light modifying means and said viewing screen that said projected rays will be reflected at an angle which is a complement of the angle through which said frame means pivots from its first to' its second positions.

6. In an arc melting furnace, the combination of a plurality of vessels each adapted to receive an ingot formed by the melting of a consumable electrode therein, frame means constructed and arranged to be moved horizontally from a first position above one vessel to a second position above another vessel, closure means carried by said frame means and selectively engagcable with the upper ends of said vessels, an electrode drive assembly mounted on said frame means and extending through said closure means for supporting an electrode in said vessels, an optical system including a pair of light modi- 9 fying means mounted on said frame means in spaced re-= lation on the opposite sides of said electrode drive as sembly and each being constructed and arranged to'receive an upwardly directed electric arc image ray and to project said rays at the same predetermined generally hori zontal direction, a viewing screen disposed for receiving said projected rays when said frame means is in its first position, first and second reflecting means mounted on said frame means and being movable therewith, each of said reflecting means being positioned between one of said light modifying means and said viewing screen when said electrode drive mechanism is in its first position, each of said reflecting means being pivotable rela tive to said frame means between an operative position in which each is effective to reflect the projected rays from a different one of said light modifying means and an inoperative position in which each is ineffective to reflect said rays, each of sad reflectors being disposed on such an angular position relative to said light modifying means and said viewing screen that said projected rays will be reflected at an angle which is a complement of the angle through which said frame means pivots from its first to its second positions.

7. In an electric arc furnace, the combination of a vessel adapted to receive molten metal, support means engageable with said vessel, electrode means carried by said support means for supporting an electrode in said vessel, optical assembly means mounted on said support means for rotation about an axis generally parallel with said electrode means, said optical assembly including tube means disposed at a predetermined angle relative to said rotational axis and having light modifying means constructed and arranged for receiving light rays from said are and for projecting said rays along the axis of tube means, second light modifying means fixedly mounted on said support means and disposed for receiving said light rays and for redirecting said light rays through a preselected angle,

8, In an electric arc furnace, the combination of a vessel adapted to receive molten metal, closure means selectively engageable with the upper end of said vessel, an electrode drive mechanism extending through said closure means for supporting an electrode in said vessel, optical assembly means mounted on said closure means for rotation about a vertical axis and disposed adjacent said electrode drive mechanism, said optical assembly including tube means disposed at a predetermined angle relative to said rotational axis and having light modifying means at its outer end and constructed and arranged for receiving upwardly directed light rays from said are and for projecting said rays along the axis of tube means, second light modifying means fixedly mounted on said closure means and disposed for receiving said light rays and for redirecting said light rays through a preselected angle 9 In an electric arc furnace, the combination of a vessel adapted to receive molten metal, support means, an electrode drive mechanism extending mounted on said support means for supporting an electrode in said vessel, an optical assembly mounted on said support means and adjacent said electrode drive mechanism, said optical as sembly including first tube means extending generally parallel with said electrode, second elongate tube means affixed to said first tube means and extending generally transversely thereto, first light modifying means mounted in said second tube means and disposed for receiving light rays directed parallel to said electrode and for redirecting said light rays along the axis of second tube means, second light modifying means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for redirecting said rays along the axis of said first tube means, means for rotating said first tube means about its axis so that said first reflecting means is moved and relative to said electrode, and third light modifying means fixedly mounted on said support means and disposed for receiving light rays which are directed along the axis of said first tube means and being operable to redirect rays through a preselected angle 10, In a consumable electrode arc melting furnace, the combination of a vessel adapted to receive an ingot. formed by the melting of a consumable electrode therein, support means above said vessel, an electrode drive mechanism mounted on said support means and extending vertically for supporting an electrode in said vessel, an. optical assembly mounted on said support means adjacent. said electrode drive mechanism, said optical assembly including first tube means extending vertically, second tube means affixed to said first tube means and extending generally transversely thereto, first reflecting means mounted in said second tube means and disposed for rereiving upwardly directed light rays and for reflecting said rays along the axis of second tube means, second refleeting means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for reflecting said rays upwardly along the axis of said first: tube means, means for rotating said first tube means about: a vertical axis so that said first reflecting means is moved relative to said electrode drive means, and light modifying means fixedly mounted on said closure means and dis posed above the upper end of said first tube means for receiving light rays directed along the axis of said first tube means and for redirecting said rays through a pre selected anglet 1L In a consumable electrode arc melting furnace, the combination of a vessel adapted to receive an ingot formed by the melting of a consumable electrode therein, clo sure means selectively engageable with the upper end of said vessel, an electrode drive mechanism extending through said closure means for supporting an electrode in said vessel, an optical assembly mounted on said closure means and adjacent said electrode drive mechanism, said optical assembly including first elongate tube means ex tending vertically through said closure means, second elongate tube means aflixed to the lower end of said first tube means and extending normally relative thereto, first reflecting means disposed at the outer end of said second tube means and disposed for receiving upwardly directed. light rays and for reflecting said rays along the axis of second tube means, second reflecting means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for reflecting said rays up= wardly along the axis of said first tube means, manually operable means for rotating said first tube means about its axis so that said first reflecting means is moved in a circu- 'lar path and relative to said electrode drive means, and light modifying means fixedly mounted on said closure means and disposed above the upper end of said first tube means for receiving light rays directed along the axis of said first tube means and for redirecting said rays through a preselected angle.

12, In a consumable electrode arc melting furnace, the combination of a vessel adapted to receive an ingot: formed by the melting of a consumable electrode therein, closure means selectively engageable with the upper end of said vessel, an electrode drive mechanism extending vertically through said closure means for supporting an electrode in said vessel, an optical assembly mounted on said closure means and adjacent said electrode drive mechanism, said optical assembly including first elongate tube means extending vertically through said closure means in substantial parallelism with said electrode drive means, second elongate tube means having one end affixed to the lower end of said first tube means and ex-' tending normally relative thereto, an opening adjacent: the other end of said second tube means and facing down wardly toward said vessel, first reflecting means disposed adjacent: the other end of said second tube opposite the opening therein for receiving upwardly directed light :rays and for reflecting said rays along the axis of second tube means, second reflecting means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for reflecting said rays upwardly along the axis of said first tube means, manually operable means for rotating said first tube means about a vertical axis so that said first reflecting means is moved a circular path and relative to said electrode drive means, and reflecting prism means fixedly mounted on said closure means and disposed above the upper end of said first tube means for receiving light rays directed along the axis of said first tube means and for reflecting said. rays through a preselected angle.

13 In an electric arc furnace, the combination of a plurality of vessels, support means constructed and arranged to be moved horizontally from a first position above one vessel to a second position above another vessel, optical assembly means mounted on said support means for rotation about a vertical axis and disposed ad" jacent said electrode drive mechanism, said optical assembly including tube means disposed at a predetermined angle relative to said rotational axis, first light modifying means at the outer end of said tube means and constructed and arranged for receiving upwardly directed light rays from said are and for redirecting said rays along the axis of tube means, second light modifying means fixedly mounted on said frame means and disposed for receiving said light rays and for projecting said light rays through a preselected angle, viewing means dis posed for receiving said projected rays when said electrode drive mechanism is in its first position, reflecting means mounted on said frame means and being movable therewith, said reflecting means being positioned to refleet said projected rays and being movable relative to said frame means between an operative position in which it is effective to reflect said projected rays and an inoperative position in which it is ineffective to reflect said rays, said reflecting means being disposed in such an angular position relative to said second light modifying means and said viewing means when said frame means is in its second position that said projected rays will be re flected to said viewing means.

14. In an electric arc furnace, the combination of a plurality of vessels, frame means constructed and arranged to be moved horizontally from a first position above one vessel to a second position above another vessel, closure means carried by said frame means and selectively engageable with the upper ends of said vessels, an electrode drive mechanism mounted on said frame means and extending through said closure means for sup porting an electrode in said vessels, an optical assembly mounted on said closure means and adjacent said electrode drive mechanism, said optical assembly including first tube means extending vertically through said closure means in substantial parallelism with said electrode drive means, second tube means having one end affixed to the lower end of said first tube means and extending normal- .ly relative thereto, first reflecting means disposed adjacent the other end of said second tube means for receiving up- Wardly directed light rays and for reflecting said rays along the axis of second tube means, second reflecting means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for reflect ing said rays upwardly along the axis of said first tube means, manually operable means for rotating said first tube means about a vertical axis so that said first reflecting said projected rays when said electrode drive means and light modifying means fixedly mounted on said frame means and disposed above the upper end of said first tube means for receiving light rays directed along the axis of said first tube means and for projecting said rays through a preselected angle, viewing means disposed for receiving said projected rays when said electrode drive mecha nism is in its first position, reflecting means mounted on. said frame means and being movable therewith, said re flecting means being positioned to reflect said projected rays and being movable relative to said frame means and between an operative position in which it is effective to reflect said projected rays and an inoperative position in which it is ineffective to reflect said rays, said reflector being disposed in such an angular position relati e to said light modifying means and said viewing means when said frame means is in its second position that said projected rays will be reflected to said viewing means,

15., In an arc melting furnace, the combination of a plurality of vessels each adapted to receive an ingot formed by the melting of a consumable electrode therein, frame means constructed and arranged to be moved horizontally from a first position above one vessel to a second position above another vessel, closure means carried. by said frame means and selectively engageable with the upper ends of said vessels, an electrode drive mechanism. mounted on said frame means and extending through said closure means for supporting an electrode in said vessels, an optical assembly mounted on said closure means and adjacent said electrode drive mechanism, said optical assembly including first elongate tube means extending vertically through said closure means in substantial parallelism with said electrode drive means, second elongate tube means having one end affixed to the lower end of said first tube means and extending normally relative thereto, an opening adjacent the other end of said second tube means and facing downwardly toward said vessel, first reflecting means disposed adjacent the other end of said second tube opposite the opening therein for receiving upwardy directed light rays and for re-- flecting said rays along the axis of second tube means, second reflecting means disposed at the juncture of said first and second tube means and oriented for receiving light rays directed along the axis of said second tube means and for reflecting said rays upwardly along the axis of said first tube means, manually operable means for rotating said first tube means about a vertical axis so that said first reflecting means is moved in a circular path and relative to said electrode drive means, and reflecting prism means fixedly mounted on said frame means and disposed above the upper end of said first tube means for receiving light rays directed along the axis of said first tube means and for reflecting said rays through a pre selected angle, a viewing screen disposed for receiving said projected rays when said electrode drive mecha nism is in its first position, reflecting means mounted on said frame means and being movable therewith, said reflecting means being positioned between said light modifying means and said viewing screen when said frame means is in its first position, said reflecting means being pivotable relative to said frame means between an opera tive position in which it is eflective to reflect said projected. rays and an inoperative position in which it is inelfective to reflect said rays, said reflector being disposed in such an angular position relative to said light modifying means and said viewing screen that said projected rays will be reflected at an angle which is a complement of the angle through which said frame means pivots from its first to its second positions References Cited UNITED STATES PATENTS BERNARD A, GILHEANY, Primary Examiner;

B, GILSON, A ssistant Examinien

Claims

1. IN AN ARC MELTING FURNACE, THE COMBINATION OF A PLURALITY OF VESSELS, SUPPORT MEANS, ELECTRODE DRIVE MEANS MOUNTED ON SAID SUPPORT MEANS FOR SUPPORTING AN ELECTRODE IN SAID VESSELS, SAID SUPPORT MEANS BEING MOVABLE FROM A FIRST POSITION ABOVE ONE OF SAID VESSELS TO A SECOND POSITION ABOVE ANOTHER OF SAID VESSELS, AN OPTICAL SYSTEM INCLUDING LIGHT MODIFYING MEANS MOUNTED ON SAID ELECTRODE DRIVE MEANS AND CONSTRUCTED AND ARRANGED TO RECEIVE AN ELECTRIC ARC IMAGE RAY AND TO PROJECT SAID RAY AT A PREDETERMINED ANGLE, VIEWING MEANS DISPOSED FOR RECEIVING SAID PROJECTED RAY WHEN SAID ELECTRODE DRIVE MECHANISM IS IN ITS FIRST POSITION, REFLECTING MEANS POSITIONED TO RECEIVE SAID PROJECTED RAYS WHEN SAID ELECTRODE DRIVE MECHANISM IS IN ITS SECOND POSITION, SAID REFLECTOR BEING DISPOSED IN SUCH AN ANGULAR POSITION RELATIVE TO SAID LIGHT MODIFYING MEANS AND SAID VIEWING MEANS THAT THE PROJECTED RAYS WILL REFLECTED TO SAID VIEWING MEANS.