Mandrel of coil box

Abstract

A mandrel of a coil box comprises: a cylindrical mandrel body having a center shaft disposed therein and a slot into which a front end portion of a hot bar is inserted; and a guide part which is arranged towards the inside of the mandrel body from a peripheral wall of one side of the slot so as to prevent the cooling and plastic deformation of the front end portion of the bar inserted through the slot.

1 . A mandrel of a coil box, the mandrel comprising:
 a cylindrical mandrel main body in which a center shaft is disposed, the mandrel main body comprising a slot to receive a leading end portion of a high-temperature bar; and   a guide part formed from an edge wall of the slot toward an inner side of the mandrel main body so as to prevent cooling and plastic deformation of the leading end portion of the bar inserted through the slot.   
     
     
         2 . The mandrel of  claim 1 , wherein the guide part protrudes from the edge wall of the slot to prevent the leading end portion of the bar from making contact with the center shaft when the leading end portion of the bar is inserted through the slot. 
     
     
         3 . The mandrel of  claim 2 , wherein an inner end of the guide part is spaced apart from an inner end of an opposite edge wall of the slot by 90 mm to 110 mm. 
     
     
         4 . The mandrel of  claim 2 , wherein the guide part is sloped in a manner such that an inner gap of the slot is smaller than an outer gap of the slot. 
     
     
         5 . The mandrel of  claim 4 , wherein an outer end of the guide part is spaced apart from an outer end of an opposite edge wall of the slot by 200 mm to 300 mm. 
     
     
         6 . The mandrel of  claim 1 , wherein the guide part is formed in one piece with the mandrel main body and extends from the edge wall of the slot toward the inner side of the mandrel main body. 
     
     
         7 . The mandrel of  claim 1 , wherein the guide part protrudes from the edge wall of the slot and tapers toward the inner side of the mandrel main body. 
     
     
         8 . The mandrel of  claim 1 , wherein a counterweight is provided on a side of the mandrel main body opposite to the guide part so as not to bias a center of gravity of the mandrel toward the guide part.