DEVELOP MENJ^S IN MANUFACTURE OF COPPER WIRE 189 



Rod Rolling Mill 



The Rod Rolling Mill equipment consists of a billet heating furnace, 

 a roughing mill, an intermediate mill, a finishing mill, coilers, conveyors, 

 and pickling tubs. The mills are water-cooled and equipped with a 

 down-draft exhaust which carries the fumes produced during the 

 rolling operation to an air washer where the copper dust is recovered 

 before the air is discharged. 



The 225 pound wire bars as received in cars from the refineries are 

 unloaded onto skids in the train shed and transported by an electric 

 truck to the charging end of the billet heating furnace. Here they are 

 transferred in groups of six by a hoist to the charging table, where a 

 compressed air-pusher moves them along through the furnace which 

 holds 120 bars. The bars are brought up to the required temperature 

 for rolling as they move through the furnace, which is heated by fuel 

 oil. When the bars reach the opposite end of the furnace they are 

 withdrawn at about 1600° F. with a pair of tongs through the discharge 

 door and pushed into the roughing mill one at a time. These tongs 

 operate on a trolley suspended from a beam, which is in line with the 

 first groove of the mill. 



The roughing mill consists of three motor-driven rolls, one above 

 the other. The bar, after passing through the first groove between the 

 top and middle roll, drops upon feed rolls set in the floor and is returned 

 through the second groove, between the middle and bottom roll ; then 

 raised into position and passed through the third groove, which is in 

 the same rolls as the first pass. Five passes are made in this manner 

 until its cross-section is reduced sufificiently for it to enter the inter- 

 mediate mill. As the bar enters the roughing mill it is 54 inches long 

 and about 4 inches square. When it leaves this mill it has been rolled 

 into an oval cross-section and is about 124 feet in length. Formerly 

 the last pass on this mill was handled manually, and recently a mechan- 

 ical repeater has been added as illustrated by Fig. 2. 



From the roughing mill the bar goes to the intermediate mill and is 

 passed through the first pair of rolls. As it emerges an operator catches 

 the end with a pair of tongs and passes it back through the next pair of 

 rolls. The increased length between each pass at the intermediate and 

 finishing mills is allowed to run out in a loop on a sloping iron covered 

 floor on each side of the rolls. This catching and returning is repeated 

 at each set of rolls until the original copper bar finally emerges a round, 

 quarter-inch rod about 1200 feet long. This last pass goes through a 

 guide pipe into a coiler, Fig. 3. The reductions in cross-section are 

 illustrated in Fig. 4. 



