FR2622078A1 - WALL ELECTRODE FOR ELECTRICAL METALLURGICAL OVEN - Google Patents

Abstract

This sole electrode for an electric metallurgical vessel or furnace, in particular with direct current, comprises a metal bar 4 intended to pass through the wall of the furnace so as to come through one end in contact with a molten metal mass contained in the furnace, the other end projecting outside the oven by a portion wrapped in a sleeve 8 of thermally conductive material, energetically cooled by a circulation of cooling fluid, and a conductive end piece 9 extending the portion of the bar projecting from the oven and connected to a terminal of the electrical supply, the end piece being secured to said bar portion by assembly means. Said assembly means 60 consist of studs 61 passing through the end piece 9 screwing into said bar portion 8, and bolted to the periphery of the end piece 9. The assembly means 60 are cold tightened with prestressing.

Description

WALL ELECTRODE FOR ELECTRICAL METALLURGICAL OVEN

  The present invention relates to a wall electrode for electric metallurgical furnace including direct current, of the type comprising in particular a solid metal bar for passing through the wall of the furnace so as to come by an end in contact with a molten metal mass contained in the oven, the other end protruding outside the oven by a portion

  wrapped in a sleeve made of thermally conductive

  cooled by a circulation of cooling fluid, and a conductive tip extending the portion of the bar protruding from the oven and connected to a terminal of the power supply, the end piece being secured to said portion of the bar by means of assembly. An electrode of this type is described in document FR-A-2 572 873. According to this document, the assembly means illustrated consist of screwing the threaded lower end of the bar into a threaded bowl of the end piece. In addition to the machining problems related to this solution, a difficulty encountered comes from the fact that the screw threads of the two assembled members tend to disintegrate in the long run, which entails the risk of starting up micro-arcs which are increasing in size. until you need to dispose of the organs. The same disadvantage obeys an alternative solution of screwing

  means of threaded sleeves ("nipples").

  Finding alternatives is difficult.

  Thus, the brazing is to be excluded because it is not possible to braze

  suitably over the entire interface between the components to be assembled.

  The purpose of the present invention is to propose assembly means not having the aforementioned drawbacks, but allowing on the contrary permanent maintenance of a good mechanical and electrical contact between the sleeve and the end piece, to ensure a electrical contact resistance as low as possible. According to the present invention, this object is achieved by the fact that the assembly means consist of studs passing through the end piece, screwing into the bar portion projecting from the furnace, and

  bolted to the periphery of the tip, on its underside.

  Advantageously, these assembly means are cold-clamped with prestressing so as to prevent their loosening under

the effect of thermal expansion.

  The invention will be better understood on reading the

  following description with reference to the single appended figure

  representing in longitudinal section the electrode equipping the sole

  a steel arc furnace with direct current.

  Reference may be made for a more detailed description

  complete with certain details shown in the figure, but not characteristic of the present invention, in the document

FR-A-2 572 873 cited above.

  Just remember that the bottom 1 of the oven is crossed by a solid cylindrical metal bar 4 whose end

  upper is in contact with the molten metal 6.

  The bar 4 passes through the shell of the oven so as to have its end portion 7 outside the oven, which portion 7 is surrounded by a cylindrical sleeve 8 and extended by a cylindrical end 9 at its lower end. The sleeve 8 and

  the tip 9 are of electrically conductive material, and advantage

  copper lining. A cooling fluid introduced through the lateral pipe 13 circulates in the helicoidal grooves 11 of the sleeve 8 to cool it, and is evacuated by the lateral pipe

15.

  The nozzle 9 has a cavity 25 inside which is disposed a cooling system 26, connected to a

  inlet 34 and a coolant outlet 35.

  In the example shown, a plate 39 of electrical connection is connected by at least one fin 41 to a cable 42 itself connected to a terminal of a power supply. Contacts 43, of the "leaf spring" type electrically connect the

sleeve 8 and the tip 9.

  It is specified that the electrical connection between the

  tation and the tip 9 could also be done directly.

  It can be provided a thrust ring 48 retained

  under the nozzle 9 by arms 49 fixed under the plate 39.

  According to the invention, the bar 4 and the end piece 9 are held applied in mechanical and electrical contact with each other by their opposite end faces 22 by means of bolts 60 distributed around the periphery of the end piece 9 and the bar 4. Each stud 61 of the bolts through a through bore 62 of the nozzle to screw into a threaded blind bore 63 of the front end of the bar 4. The other end of the stud 61 receives a washer 64 and a Tightening nut 65. The bolts are cold-clamped with prestressing to compensate for the effects of hot stud expansion. To allow mounting of the bolts, the stop ring 48 has the necessary recesses. Only one bolt 60 is shown in the figure: it is clear that as many as are necessary,

  equipartis on the periphery of the tip and the bar 4.

Claims (2)

  1. Sole electrode for an electric metallurgical vessel or furnace, especially a direct current furnace of the type comprising a metal bar (4) intended to pass through the wall of the furnace so as to come from an end in contact with a molten metal mass contained in the oven, the other end protruding outside the oven by a portion wrapped in a sleeve (8) of thermally conductive material, vigorously cooled by a circulation of cooling fluid, and a tip (9) conducting extending the portion of the bar protruding from the oven and connected to a terminal of the power supply, the end piece being secured to said bar portion by assembly means, characterized in that said connecting means (60) consist of studs (61) passing through the tip (9) screwing into said bar portion (8), and   bolted to the periphery of the tip (9).   2. Electrode according to claim 1, characterized in that the connecting means (60) are cold-tight with prestressing.