New fog cooling facilities for billets have been developed at Kamaishi Works, Nippon Steel Corporation. The facilities have a walking beam type cooling bed, and as-rolled hot billets are arranged on their corners and rotated on the bed in walking.
The billets are natural-cooled from the initial temperature to about 550°C (core temperature) at the front part of bed and then fog-jet-cooled to about 100 °C at the later part.
In this report the following items are described: the new techniques developed, the basic design and main specifications of the facilities, the passages of constructions and operational performances, improved points and unsettled problems, and others.
Main techniques developed are the billet straightening mechanism using billet pusher, the system of oncorner arrangement and rotation of billets on the cooling bed, and the fog jet cooling device of billets having the crossflow type nozzles.
This instalation has been smoothly operated since June 1975 with a sufficient cooling capacity using the fogcooling method for all billets containing carbon lower than 0.75 wt%. This has given no cracking and less deformation, very small reject level of billets (about 0.05%), and no nozzle clogging for about eight years.
