ОПРЕДЕЛЕНИЕ ПОЛЯ ТЕМПЕРАТУРВ РАБОЧИХ ВАЛКАХ ХОЛОДНОЙ ПРОКАТКИ ПРИ СКОРОСТНОМ НАГРЕВЕ В КАМЕРНОЙ ПЕЧИ

Abstract

The present article demonstrates the results of experimental and calculated researches of the rapid (gradient) heating of the working layer of the cold working roll barrel in the unit, consisting of a chamber furnace with special design and a spraying unit, located under the furnace in special pit and able to move up for rapid cooling of the working roll layer. In the process of the roll heating its barrel and some parts of the necks are located within the working chamber area while the other (external) parts of the necks are situated outside the heating chamber and rest upon the drive rollers, which are designed to ensure rotation of the roll barrel in the course of its heating and subsequent cooling. Therefore, it is necessary to ensure hardening only of the working roll layer that is why the neck parts located inside the furnace are equipped with special heat-insulated inserts to prevent their hardening. The experimental rolls are equipped with the thermocouples to measure temperature both in different points of their surface and in the depth of their barrel and necks with the aim to develop the various roll heat treatment conditions. A process of heat treatment included rigid requirements concerning smoothness of the roll barrel surface heating at very close limits for under-heating zones in the extreme sections near surface end faces. Besides, it was necessary to ensure low temperature of the necks located within the working furnace area. The experimental researches of the temperature fields under different conditions of the rapid roll heating allowed us to reach a high speed of the roll heating and cooling and, respectively, the required structure of the working roll barrel layer. At the same time, in the process of the experimental researches and calculations of the temperature fields according to the specially developed program, the authors have revealed intensive heat leak via external open neck parts under the existing conditions of heating gas input and output and roll location with the necks being, par- tially, beyond the heating chamber. The above-mentioned researches allowed revealing also a sufficient (as compared with the admissible one) non-uniformity of the temperature field of the barrel surface in the end zones of the roll being heated. It was also determined in the course of the experimental researches that change of the external heat exchange conditions between the working furnace area and roll surface does not eliminate non-uniformity of the temperature field in the end surface sections. A method of sufficient non-uniformity decrease of heating of the end roll barrel sections has been offered and executed calculations and analysis of the temperature fields have confirmed the reality of its application. © 2017, National University of Science and Technology MISIS. All rights reserved.