Research And Exploitation Of Rolling Technology For Round Bar Slitting

In bar rolling production, the output of small-size products can be greatly increased by slitting technology. High precision in round bar slitting technology is extremely wanted. This paper researches the development condition and technological achievements in bar slitting technology at home and abroad. It is thought that the technology for rebar slitting is much more matured than that of bar slitting and the research and application in round bar slitting is much less at present, the industrial and experimental feasibility and the exploiting difficulties of round bar slitting technology in the continuous bar mill of Bayi Iron & Steel Co. Ltd. have been analyzed carefully.In combination with the experiments on site, it is thought that club-square pass sequence is suited for the small-size product with high coefficient of elongation and large reduction of area and the round bar slitting rolling with high precision controlling. Pass K3 is chosen for slitting stand. The coercive spread of the rolling piece is evident in pre-slitting pass during the beginning and final periods of rolling. In slitting pass, the spread is basically linear with draught. Dimension and proportion of horizontal and vertical component of force should be well adjusted in slitting pass, which should avoid the rolling piece full in the pass. Spread coefficient should be 1.2-1.39, and the rolling piece is in the condition of free spread. The draught of the slitting wedge is well distributed in pre-slitting and slitting pass. The suitable vertex angle range of slitting wedge is 55 -65 . Position Bp of the neutral surface for metal particle moving in slitting pass is Bp =(0.4 ~0.48 )B.Through production test and calculation, it is thought that spread models of Pass K8 and K7 in round-oval set up by T.K.Shinokura's formula , that of Pass K6 and K5 indiamond-club square set up by B.K.Smianoph's formula and that of Pass K4 & K3 in pre-slitting and slitting set up by Z.Wusatowski's formula are suited for the spreading calculation of round bar slitting . In the meanwhile we got from practice that to guarantee the dimension precision of round bar slitting, carbide composite rolls should be used in finishing slitting pass sequence and loop height of the rolling piece should be preciously controlled after slitting.Finally through the test of finishing products, it is proven that the round bar produced by slitting technology can completely meet the requirement of the quality . The slitting rolling will become the main method in production of small-size products in modern bar mill and has great value , superiority and prosperity in technology and economy. The research and exploitation of technology for round bar slitting rolling stands for the new high level in domestic slitting technology.