Technological method for reducing belt breaking times in rolling mill starting

Abstract

The invention provides a technological method for reducing belt breaking times in rolling mill starting. The technological method for reducing belt breaking times in rolling mill starting is applied to the technical field of cold-rolled sheet steel rolling processes and comprises the steps of (1) increasing the set target thickness at the band steel outlet portion by 30%-40% before a rolling mill shuts down; (2) reducing positive roll bending force exerted by machine frames onto working rolls after a target thickness value is increased; (3) modifying the target thickness and shutting down the rolling mill after weld joints are sheared by the rolling mill; and (4) recovering the target thickness before the rolling mill is started again and recovering the positive roll bending force of the machine frames after rolling is stable. By means of the technological method, happened belt breaking accidents in starting can be solved when the rolling mill is started, accordingly unit yield is improved, and the number of abnormally offline rolls is decreased. The yield can be improved by decreasing the belt breaking times in starting, and the number of the abnormally offline rolls caused by belt breaking is obviously reduced.

Description

technical field [0001] The invention belongs to the technical field of cold-rolled thin-plate rolling, and more specifically relates to a process method for reducing strip breakage at the start-up of a rolling mill. Background technique [0002] The tandem cold rolling unit is a full continuous four-stand (the four stands are respectively stand F1, stand F2, stand F3, stand F4) six-roller full-hydraulic pressing AGC rolling mill, and the specifications of rolled products are related to the thickness and width of the outlet. Both are required. When the thickness of the hot-rolled incoming material is within the tolerance range and the dynamic specification meets the process requirements, the automatic thickness control system of the rolling mill can maintain high-efficiency rolling, and the head and tail lengths of the strip can be effectively controlled. The efficiency is higher. However, this production method is based on the continuous rolling of the unit. Once the unit ...

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Problems solved by technology

However, this production method is based on the continuous rolling of the unit. Once the unit shuts down and restarts (such as process roll change, abnormal shutdown), it is necessary to re-establish a steady-state rolling process to make the thickness of the finished strip meet the set requirements. , and the thin-gauge strip steel has the characteristics of weak resistance to tensile cracking. During the start-up process, it is often affected by factors such as the speed matching of each stand of the rolling mill and the inconsistency of the line speed caused by the difference in roll diameter. , which not only seriously affects the production efficiency, but also affects the unit composition rate and the online service life of the roll.

Although the same type of units at home and abroad can reduce broken belts by pre-pressing each frame before starting, but the length of the part with the thickness of the head is too large to increase the yield loss.

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