Optimized Graphite Electrode Pin Configuration

Abstract

A pin for use in connecting graphite electrodes into a joint, where the pin has at least one male tang having a tang factor, defined as the ratio of male tang length to diameter of the electrode into which hit is to be threaded, of at least about 1.0.

1 . A pin for use in a forming a graphite electrode joint, the pin comprising at least one male tang having a ratio of male tang length to diameter of the electrode into which it is to be threaded of at least about 1.0. 
     
     
         2 . The pin of  claim 1 , wherein the ratio of the diameter of the male tang at its base to male tang length is no greater than about 2.5 times the ratio of male tang length to the diameter of the electrode into which it is to be threaded. 
     
     
         3 . The pin of  claim 2 , wherein the ratio of the diameter of the male tang at its base to male tang length varies with the ratio of male tang length to electrode diameter such that for every 0.01 higher than 0.60 the ratio of male tang length to electrode diameter is, the ratio of the diameter of the male tang at its base to the ratio of male tang length to electrode diameter should be about 0.016 lower than 2.5. 
     
     
         4 . The pin of  claim 1 , wherein for a pin having a ratio of male tang length to electrode diameter of 0.85 or lower, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter is at least about 15. 
     
     
         5 . The pin of  claim 4 , wherein the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter varies with the ratio of male tang length to electrode diameter such that for every 0.01 lower than 0.85 the ratio of male tang length to electrode diameter is, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter should be about 1.25 higher than 15. 
     
     
         6 . The pin of  claim 1 , wherein the ratio of male tang length to diameter of the electrode into which it is to be threaded is no greater than about 1.2. 
     
     
         7 . An electrode joint comprising a pin and two graphite electrodes, the pin having a male tang having a ratio of male tang length to diameter of at least one of the electrodes of at least about 1.0, and the at least one electrode comprising a female threaded socket, wherein the male threaded tang engages the female threaded socket to form the joint. 
     
     
         8 . The joint of  claim 7 , wherein the ratio of the diameter of the male tang at its base to male tang length is no greater than about 2.5 times the ratio of male tang length to electrode diameter. 
     
     
         9 . The joint of  claim 8 , wherein the ratio of the diameter of the male tang at its base to male tang length varies with the ratio of male tang length to electrode diameter such that for every 0.01 higher than 0.60 the ratio of male tang length to electrode diameter is, the ratio of the diameter of the male tang at its base to the ratio of male tang length to electrode diameter should be about 0.016 lower than 2.5. 
     
     
         10 . The joint of  claim 7 , wherein for a pin having a ratio of male tang length to electrode diameter of 0.85 or lower, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter is at least about 15. 
     
     
         11 . The joint of  claim 10 , wherein the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter varies with the ratio of male tang length to electrode diameter such that for every 0.01 lower than 0.85 the ratio of male tang length to electrode diameter is, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter should be about 1.25 higher than 15. 
     
     
         12 . The joint of  claim 7 , wherein the ratio of male tang length to diameter of the electrode into which it is to be threaded is no greater than about 1.2. 
     
     
         13 . A process for preparing a pin for use in forming a graphite electrode joint, the process comprising
 (a) mixing coke and a pitch binder, to form a stock blend;   (b) extruding the stock blend to form a green stock;   (c) baking the green stock to form a carbonized stock;   (d) graphitizing the carbonized stock by maintaining the carbonized stock at a temperature of at least about 2500° C. to form a graphitized stock;   (e) machining the graphitized stock so as to form a pin having at least one male tang having a ratio of male tang length to diameter of the electrode into which it is to be threaded of at least about 1.0.   
     
     
         14 . The process of  claim 13 , wherein the ratio of the diameter of the male tang at its base to male tang length is no greater than about 2.5 times the ratio of male tang length to electrode diameter. 
     
     
         15 . The process of  claim 14 , wherein the ratio of the diameter of the male tang at its base to male tang length varies with the ratio of male tang length to electrode diameter such that for every 0.01 higher than 0.60 the ratio of male tang length to electrode diameter is, the ratio of the diameter of the male tang at its base to the ratio of male tang length to electrode diameter should be about 0.016 lower than 2.5. 
     
     
         16 . The process of  claim 13 , wherein for a pin having a ratio of male tang length to electrode diameter of 0.85 or lower, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter is at least about 15. 
     
     
         17 . The process of  claim 16 , wherein the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter varies with the ratio of male tang length to electrode diameter such that for every 0.01 lower than 0.85 the ratio of male tang length to electrode diameter is, the ratio of the taper of the male tang to the ratio of male tang length to electrode diameter should be about 1.25 higher than 15. 
     
     
         18 . The process of  claim 13 , wherein the ratio of male tang length to diameter of the electrode into which it is to be threaded is no greater than about 1.2. 
     
     
         19 . A pin for use in forming a graphite electrode joint, the pin comprising two symmetrical male tangs wherein a ratio of the diameter of each male tang at its base to male tang length is no greater than about 2.5 times the ratio of the male tang length to the diameter of the electrode into which it is to be threaded, whereby the joint exhibits improved thermal and mechanical stresses as compared to a joint with a conventional pin. 
     
     
         20 . The pin of  claim 19  wherein the electrode column exhibits improved strength. 
     
     
         21 . The pin of  claim 19  wherein the ratio of the male tang length to the diameter of the electrode comprises at least about 0.6. 
     
     
         22 . The pin of  claim 21  wherein the ratio of the male tang length to the diameter of the electrode comprises at least about 0.85. 
     
     
         23 . The pin of  claim 19  wherein the pin formed of the same material as the electrode. 
     
     
         24 . The pin of  claim 19  wherein the electrode diameter comprises about 220 mm to about 700 mm.