Ring roll replacing method in bar steel rolling mill and device therefor

Abstract

The present invention relates to a method and apparatus for changing ring rolls of a bar and wire rod mill which makes roll changing work easy and in particular to a method for changing only the ring rolls without disassembling the housing in accordance with an optimum process. The method for changing ring rolls in a bar and wire rod mill having a plurality of roll assemblies incorporated into a housing and arranged in equiangular positions in circumferential direction comprises the steps of disengaging the interference fit between the spent ring rolls and the roll shaft, withdrawing the spent ring rolls by moving the roll shaft in an axial direction, changing the spent ring rolls with new ring rolls in the housing, inserting the roll shaft into the new ring rolls, and engaging the new ring rolls in interference fit with the roll shaft. Additionally, a main body of a bar and wire rod mill comprising a roll shaft suspending apparatus and a mechanism suitable for the method according to the present invention are provided.

1 . A method for changing ring rolls in a bar and wire rod mill having a plurality of roll assemblies incorporated into a housing and arranged in equiangular positions in circumferential direction, characterized by comprising the steps of: 
 disengaging a spent ring roll and its roll shaft from interference fit;    withdrawing the spent ring roll by moving the roll shaft in the axial direction;    changing the spent ring roll for a new ring roll in the housing;    inserting the roll shaft into the new ring roll; and    engaging the new ring roll and the roll shaft in interference fit each other.    
     
     
         2 . The method according to  claim 1 , wherein hydraulic oil pressure is used for engaging and disengaging the ring roll and the roll shaft in and from interference fit.  
     
     
         3 . The method according to  claim 2 , further comprising the steps of: 
 holding the roll shaft of the roll assembly, in which the spent roll is to be changed, in an upright position before disengaging the spent ring roll and the roll shaft from the interference fit; and    coupling a suspending apparatus with one end of the roll shaft and connecting a hydraulic oil passage within the roll shaft to a hydraulic oil source through said end of the roll shaft before withdrawing the roll shaft from the spent ring roll.    
     
     
         4 . A bar and wire rod mill comprising a plurality of roll assemblies each having a ring roll capable of engaging and disengaging a roll shaft in and from interference fit, wherein the roll shaft is movable in the axial direction within a housing said plurality of roll assemblies being arranged in equiangular positions around a pass and supported by said housing.  
     
     
         5 . The bar and wire rod mill according to  claim 4 , wherein each roll assembly comprises: 
 a mechanism for engaging or disengaging the ring roll and the roll shaft in and from interference fit by means of hydraulic oil, with the inner surface of the ring roll and the journal part of the roll shaft having a tapered surface;    hydraulic oil passage extending through the roll shaft from one end portion of the roll shaft; and    a hydraulic oil inlet and a suspension jig receiving member provided on one end of the roll shaft.    
     
     
         6 . The bar and wire rod mill according to  claim 5  wherein there are four roll assemblies.  
     
     
         7 . A roll shaft suspending apparatus comprising: 
 a nozzle for injecting hydraulic oil into an oil inlet provided on one end portion of a roll shaft of a roll assembly;    a rod holding said nozzle on the top end portion thereof and having a hydraulic oil passage therethrough connecting with said nozzle;    a cylinder embracing said rod for actuating it reciprocally by hydraulic oil pressure; and    a suspension jig for engaging with a suspension jig receiving member provided on one end of said roll shaft.    
     
     
         8 . The roll shaft suspending apparatus according to  claim 8 , wherein said rod holds said nozzle through a resilient seat.