APPARATUS FOR REDUCING ROLLING FORCE CONTROL SECTION TO MINIMUM WHEN WELDED STRIP PASSES THROUGH SKIN LASS MILL AND APPLYING MINIMUM ROLLING FORCE TO STRIP DURING CONTROL SECTION

摘要

PURPOSE: To provide an apparatus for controlling rolling force and line speed in a welded strip section by simultaneously reducing a rolling force control section to the minimum at a time point when a welded strip passes through a skin pass mill and applying the minimum rolling force to the strip during the control section to reduce center marks, prevent damage of rolling rolls and improve surface quality of cold rolled finished product accordingly. CONSTITUTION: The apparatus for controlling rolling force and line speed in a welded strip section comprises a welded portion tracking part(105) installed at the input side of a skin pass mill(100) to detect in advance a welded portion of strip on which a strip tracking hole is formed; a length calculation part(106) for detecting rotation of strip transfer rollers and calculating a distance between the welded portion and the skin pass mill based on the rotation from a time point when the welded portion tracking part detects the welded portion; a rolling force variation setting part(102) for selectively providing a normal rolling force predetermined according to a set variation control signal or a rolling force value on the welded portion at a time point corresponding to a certain distance in front of the skin pass mill before reaching the skin pass mill; a PLC(programmable logic controller)(103) for controlling rolling force using a rolling force value set by the rolling force variation setting part during a preset period of time and controlling line speed using different line speed values step by step during a certain period of time before and after the welded portion passes through the skin pass mill when the welded portion is detected while controlling rolling force and line speed based on rolling data from a supervisory control computer(101); a rolling force control part(104) for controlling rolling force by dividing rolling force of the skin pass mill into rolling force during passing of the welded portion and normal rolling force according to control of the PLC; and a speed control part(107) for firstly decelerating line speed if the welded portion is detected by the welded portion tracking part, secondly decelerating line speed at a time point corresponding to a certain distance from the skin pass mill before the welded portion detected by the length calculation part passes through the skin pass mill, and then automatically accelerating line speed at a time point corresponding to a certain distance from the skin pass mill after the welded portion passes through the skin pass mill.