US2997511A - Water-cooled electrode head or the like - Google Patents

Description

Aug. 22, 1961 A. H. TURNER ,51

WATER-COOLED ELECTRODE HEAD OR THE LIKE Filed Dec. 2. 1959 IN V EN TOR.

A/f'req H. 7Zlrner BY flfforweqs United States Patent fiice 2,997,511 Patented Aug. 22, 1961 bama Filed Dec. 2, 1959, Ser. No. 856,765 6 Claims. (CI. 1315) This invention relates to water-cooled devices or members, such as electrode heads for electric furnaces or the like.

In the past, water-cooled members, such as electrode heads for electric furnaces, have generally been made in the form of castings, with cooling coils embedded therein. Copper is generally employed in casting such electrode heads, because of the high electrical conductivity and high heat conductivity of copper. The cooling coils have generally been fabricated separately from tubing or pipe made of ordinary steel, stainless steel, Monel, copper or the like. However, copper tubing or pipe is seldom used because of the difliculty in casting copper to copper and in holding the form of the tubing. In making an electrode head, it has been the practice to place the cooling coil in the casting mold. The copper is then cast around the cooling coil so that the coil will be embedded in the finished casting. When the electrode head is used, water or some other coolant is pumped through the coil so as to keep the electrode head reasonably cool.

However, it has been found that the steel, stainless steel, Monel or other similar metal employed in the cooling coil impedes the transfer of heat from the electrode head to the cooling water which flows through the coil. The metal of the cooling coil virtually always has a much lower heat conductivity than the copper employed in the electrode head. This factor greatly diminishes the cooling efficiency of the cooling coil. Moreover, the cooling coil offers a substantial resistance to the flow of cooling water therethrough, due to the relatively small crosssection of the pipe or tubing employed in the cooling coil.

Difiiculties have also been experienced in casting the copper around the cooling coil. Virtually in every case, the finished castings contain voids or other imperfections around the cooling coils. Of course, any such voids afford additional resistance to the transfer of heat between the electrode head and the cooling water. Moreover, the copper oxide particles, which form in the melted copper, adhere to the relatively cool surface of the tubing and form a thermal dam which impedes the flow of heat between the cast copper and the tubing.

Because of insuflicient heat transfer between the electrode head and the cooling water, it has often been found that the electrode head is heated to excessively high temperatures during the operation of the electric furnace. This tends to cause rapid deterioration and premature failure of electrode heads. This problem is of considerable importance because it is costly and wasteful to shut down an electric furnace in order to repair or replace an electrode head. Moreover, the power transmission capabality of the electrode head is limited by its tendency to heat up excessively, because the temperature rise in the lead is a function of the electrical current carried by the head. Thus, the inadequate cooling of the lead limits its current rating.

One object of the present invention is to provide a new and improved water-cooled electrode head or other member, in which the. cooling water directly engages the cop per body of the electrode head, without any intervening cooling coil, so that heat will be transferred very efliciently between the copper and the cooling water.

A further object is to provide such a new and improved electrode head or the like, which is provided with cooling passages of great cross-section, so as to afford an extremely low resistance to the passage of cooling water therethrough.

Another object is to provide a new and improved electrode head of the foregoing character, which is fabricated by welding copper plates to a basic copper casting, so that the entire electrode head is made of copper, for maximum efliciency of heat transfer.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a plan view of an electrode head to be described as an illustrative embodiment of the present invention.

FIG. 2 is an elevational view of the electrode head.

FIG. 3 is a horizontal cross-section, taken generally along a line 33 in FIG. 2.

FIG. 4 is a vertical section, taken generally along a line 4-4 in FIG. 1.

FIG. 5 is a side elevational View, taken as indicated by the line 55 in FIG. 2.

FIGS. 6 and 7 are fragmentary elevational sectional views, taken generally along the lines 66 and 7-7 in FIG. 1.

As already indicated, the drawings illustrate an electrode head 10 for use with an electric furnace or the like. It will be understood, however, that the invention is applicable to a variety of other water-cooled members, in addition to the electrode head 10.

As shown to advantage in FIG. 1, the electrode head 10 is adapted to receive and hold a cylindrical rod-shaped electrode 12. An electric furnace generally has three electrodes and three electrode heads to hold the electrodes. The three electrodes are energized from a source of three-phase alternating current so that arcs may be established and maintained between the electrodes. The arcs develop a great deal of heat, so that the steel or other metal in the furnace may be maintained in a molten condition.

It will be seen that the electrode head 10 is generally in the form of a ring-shaped sleeve. An opening 14 is formed in the electrode head 10 to receive the electrode 12. The opening 14 is generally circular in shape but not strictly so, in the illustrated construction. Within the opening 14, the electrode head 10 is formed with a cylindrically curved internal surface 16 adapted to be engaged by the electrode 12, as shown to advantage in FIG. 1. The electrode 12 may be clamped against the cylindrically curved surface 16 by a suitable mechanism, not shown. In the illustrated electrode head 10, the cylindrically curved surface 16 extends through somewhat less than a semi-circle. Opposite the cylindrically curved surface 16, there is an arcuate clearance space 18 between the electrode 12 and electrode head 10.

As shown to advantage in FIG. 4, the electrode head 10 may comprise a basic casting 20, which is preferably made of copper, because of the high electrical conductivity and heat conductivity of copper. The cylindrically curved surface 16 is formed on the inside of the casting 20. As shown, the casting 20 is generally in the form of a ring-shaped sleeve. On one side, the casting or sleeve 20 is formed with mounting flanges or brackets 22. Mounting holes 24 are for-med in the flanges 22. Opposite the cylindrically curved surface 16, a large opening 26 extends through the wall of the sleeve 20. It will be seen that the opening 26 is substantially at the center of a flat longitudinal side surface 28 which extends outwardly along the mounting. flanges 22.

As shown to advantage in FIG. 4, the casting or sleeve 20 has a reduced portion 30 which extends along most of the length of the sleeve. Below the reduced portion 30, the sleeve 20 has a shoulder or flange 32. The reduced portion 30 extends part-Way around the sleeve 20, between points adjacent the mounting flanges 22. As shown to advantage in FIG. 3, the reduced portion 30 terminates in longitudinal, generally radial end surfaces 34 and 36. At the upper end of the cylindrically curved surface 16, the sleeve 2% has an internal, beveled surface 38 to facilitate the insertion of the electrode 12 into the opening 14.

Part of the heat developed by the electric arcs is conducted up the electrodes 12 to the electrode head Iii. To prevent the electrode from being overheated, provision is made for cooling the electrode head with water or some other suitable cooling fluid. Thus, the illustrated electrode head 10 is provided with a curved plate 46 which forms a jacket or sheath around the reduced portion 30. The plate 4! is spaced outwardly from the reduced portion 30 so as to form a space 42 therebetween, adapted to receive and to carry the cooling water or other coolant. The plate 40 is preferably made of copper so as to have an extremely high heat conductivity.

The copper plate 44} is generally cylindrical in curvature although not strictly so, in the illustrated embodiment.

As shown to advantage in FIG. 3, the curved plate 40 extends between the end surfaces 34 and 36 of the reduced portion 30. At its lower end, the plate 40 engages the enlarged flange or shoulder 32. The upper end of the plate 40 has an inwardly turned portion 44 which engages the reduced portion 30 at the upper end of the sleeve 20.

All around its edges, the plate 40 is welded or otherwise secured to the casting or sleeve 20. Thus, welds 46 and 48 are formed between the edges of the plate 40 and the end surfaces 34 and 36 of the reduced portion 3t Similarly, welds 50 and 52 are formed at the upper and lower edges of the plate 40, to join the plate to the casting 20. The welds 46, 48, t), and 52 actually comprise portions of a single continuous weld, which may be formed by heliarc welding, in which the arc is shielded by a curtain of helium gas.

Illustrated electrode head is formed with ports 54 and 56 which communicate with the space 42 between the sleeve 2t] and the curved plate 440. The ports 54 and 56 may be internally threaded to receive suitable pipes or tubing for carrying water or some other coolant to and from the electrode head. In this case, the ports 54 and 56 are formed in the top of the electrode head 10, adjacent the mounting flanges 22. The port 54 extends downwardly for a considerable distance to a horizontal passage 5'8 which opens through the end wall 34 adjacent the bottom of the reduced portion 30. Thus, the port 54 communicates with the lower end of the space 42 adjacent the end wall or surface 34. In the illustrated arrangement, the port 56 extends downwardly only a short distance to horizontal passage 60 which opens into the space 42 through the end surface 36 adjacent the upper end of the space 42.

One or more dividers may be mounted between the sleeve and the curved plate 40, so as to divide the space 42 into a plurality of portions which are arranged to form a sinuous passage between the ports 54 and 56. In the illustrated arrangement, two such dividers or partitions 62 and 64 are employed. The illustrated dividers 62 and 64 are arcuate in shape and are disposed radially between the reduced portion 30 and the curved plate 40. Thus, the dividers 62 and 64 divide the space 42 into three portions 66, 68 and 70. As already indicated, the dividers 62 and 64 are arranged so that the ends of the portions 66, 63 and 70 are interconnected to form a sinuous passage, extending continuously between the ports 54 and 56.

Thus, the upper divider 62 is of such a length that an opening 72 is formed between the divider 62 and the end wall or surface 34. At its opposite end, the divider 4 62 engages the end surface 36. An opening or space 74 is formed between one end of the lower divider 64 and the end surface 36. The other end of the divider 64 engages the end wall 34.

It will be apparent that water or some other coolant can flow downwardly through the port 54 and then through the lower space 70, the opening 74, the intermediate space 68, the opening 72, and the upper space 66 to the port 56. In traveling between the ports 54 and 56, the water traverses the arcuate length of the space 42 three times. As shown, the intermediate space 68 is smaller than the upper space 66, while the lower space 7 0 is still smaller.

The dividers 62 and 64 may be fabricated from copper plate or bar stock and may be welded to the sleeve 20. Here again, the welds may be formed by heliarc welding.

It will be apparent that the water or other coolant is in direct contact with the copper sleeve 20 and the copper plate 40. Thus, there is nothing to impede the transfer of heat between the copper electrode head and the water. Accordingly, maximum efficiency of heat transfer is assured. The cross-sectional areas of the passage portions 66, 68 and 70 are unusually great, so that a large amount of cooling water will be forced through the electrode head for any given water pressure. Thus, the illustrated construction affords extremely eificient water cooling of the electrode head.

It has been found that the illustrated electrode head may be cooled much more effectively than prior heads, so much so, that the load current to the electrodes can be increased 50%. The need for maintenance and replacement of the electrode heads has been greatly reduced. With former heads, the electrode was generally observed to be red-hot up to the lower end of the head. With the illustrated electrode head, the electrode is cooied so much more effectively that it shows no color for a considerable distance below the electrode heads. With the illustrated construction, the flexible electrical leads to the electrodes have been found to be cool enough to touch with the hand. Formerly, such leads were hot enough to vaporize water.

The new electrode head construction, in which copper plates are welded to a copper casting, eliminates the difiiculties which have been experienced in casting copper around cooling pipes or coils. Voids and other imperfections in finished castings are eliminated.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

I claim:

1. An electrode head for holding a generally cylindrical electrode, said electrode head comprising a copper casting in the form of a ring-shaped sleeve having an electrodereceiving opening therein, said sleeve having an internal cylindrically curved electrode engaging surface within said opening, said sleeve having an externally reduced portion with a flange portion at one end thereof, said reduced portion extending between said flange and the opposite end of said sleeve, a curved copper plate extending around said reduced portion and spaced outwardly therefrom to form a water jacket therearound, said plate extending between said flange and the opposite end of said sleeve, said plate having an in-turned end portion engaging said opposite end of said sleeve, said plate having its edges welded to said sleeve, said sleeve having a pair of ports therein leading to opposite ends of the space between said sleeve and said plate, and a pair of arcuate radial dividers extending between said reduced portion and said plate for dividing said space into three sections, said dividers being arranged with openings between said sleeve and opposite ends of said dividers for connecting said three sections to form a sinuous fluid passage extending continuously between said ports.

2. An electrode head for holding a generally cylindrical electrode, said electrode head comprising a metal casting in the form of a ring-shaped sleeve having an electrodereceiving opening therein, said sleeve having an externally reduced portion, a curved metal plate extending around said reduced portion and spaced outwardly therefrom to form a water jacket therearound, said plate having its edges welded to said sleeve, said sleeve having a pair of ports therein leading to opposite ends of the space between said sleeve and said plate, and an arcuate radial divider extending between said reduced portion and said plate for dividing said space into a plurality of sections, said divider being arranged with an opening between said sleeve and one end of said divider for connecting said sections to form a sinuous fluid passage extending continuously between said ports.

3. An electrode head, comprising a metal casting in the form of a ring-shaped sleeve having an electrode-receiving opening therein, said sleeve having an externally reduced portion, a curved metal plate extending around said reduced portion and spaced outwardly therefrom to form a coolant jacket therearound, said plate having its edges welded to said sleeve, said head having a pair of ports therein leading to opposite ends of the space between said sleeve and said plate, and a plurality of dividers extending between said reduced portion and said plate for dividing said space into a plurality of sections, each of said dividers being arranged with an opening between said sleeve and one end of said dividers for connecting said sections to form a sinuous fluid passage extending continuously between said ports.

4. A fluid-cooled member, comprising a metal casting having a reduced portion, a metal plate extending over said reduced portion and spaced outwardly therefrom to form a space therebetween, said plate having its edges welded to said casting, said member having a pair of ports therein leading to opposite ends of said space between said casting and said plate, and a plurality of metal dividers welded to said casting and extending between said reduced portion and said plate for dividing said space into a plurality of sections, each of said dividers being arranged with an opening between said casting and one end of said divider for interconnecting said sections of said space to form a continuous fluid passage extending between said ports.

5. A fluid cooled member, comprising a metal casting having a recess therein, and a metal plate mounted on said casting and closing said recess to form a passage between said casting and said plate, said member having entrance and exit ports therein leading to said passage.

6. A fluid cooled member, comprising a metal casting having an elongated recess therein, and a metal plate welded to said casting and covering said recess to form a fluid passage between said casting and said plate, said member having entrance and exit ports therein leading to opposite end portions of said passage.

References Cited in the file of this patent UNITED STATES PATENTS 1,990,482 Gebhard Feb. 12, 1935 2,098,380 Eaglemann et a1. Nov. 9, 1937 2,657,019 Schmitt Oct. 27, 1953

Images