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Guide 2023 05 30T063207 505

TECHNOLOGY NIPPON STEEL TECHNICAL REPORT No JANUARY Outline of Free Size Rolling for Hikari Wire Rod and Bar Mill Introduction The Hikari Wire Rod Bar Mill began commercial operation in as Japan ? s first fully continuous wire rod mill for carbon steel The Mill started production of stainless steel wire rods in Today it is dedicated to the production of stainless steel bars and wire rods In the meantime various improvements were introduced in the Mill For example the processes after the No intermediate train were modernized in and in-line solution treatment was introduced in In new technologies to reinforce the Mill were developed and introduced They include the highly efficient billet heating system a complex heating system that combines a walking beam-type reheating furnace and an induction heater for improving product quality and the helical rolling mill for implementing an inline blooming process Stainless steel bars and wire rods which undergo secondary and tertiary forming processes are widely used in the forming of screws bolts pins shafts springs and welding rod for automobiles office automation equipment etc Because of their many uses stainless steel bars and wire rods are manufactured in a wide variety of grades Thus they are characterized by small volume production in various sizes and grades At the Mill wire rods - to -mm n and bars - to mm n are rolled by one strand Wire rod is finish-rolled by a notwist mill NT mill and wound by a laying head A thicker wire rod bar-in-coil is wound on a pouring reel and bars are pooled on a cooling bed installed on a line branched out from the intermediate train for rolling wire rods see Fig In recent years market demand for stainless steel products has become increasingly rigorous Accordingly the demand for higher dimensional accuracy shorter delivery time and fewer surface defects in stainless steel bars and wire rods as materials for stainless steel products has become conspicuous Under such conditions to improve product quality and productivity we introduced a high-rigidity -roll mill reducing sizing mill RSB made by Kocks and a new type of conveyor line in November Looking at the rolling equipment the RSB was installed after the Fig Layout of Hikari Wire Rod Bar Mill before installation of RSB intermediate train as the finishing mill for thicker wire rods and bars to improve their dimensional accuracy and implement size-free rolling In addition the dimensional accuracy of thinner wire rods was improved by stabilizing the dimensions of steel material at the NT mill entrance after introduction of the RSB Furthermore the time required for roll changing was shortened by adopting roll assemblies for the RSB rolling stands As a measure to reduce surface defects the repeater that had been used to guide the steel from the intermediate train to the pre-finishing mill was replaced with a new conveyor line using continuous roller guides As a result of the above modifications we were able to improve the dimensional accuracy shorten the roll-changing