Evaluation for Lubricity of Lubricant by Simulation Testing Machine Developed Newly on Hot Rolling

摘要

Recently. rolls made of high speed steel(HSS)which are superior to wear and abrasion resistanceare used in many hot rolling mills. However, sometroubles are occurred due to by the use of the HSS roll.To solve these problems, new lubricants are developedand the lubricities of them are estimated by using thetwo-disk testing machine or the pin-on-disk testingmachine. But the evaluation obtained by these testingmachines are different from one of the actual rollingprocessing. In order to evaluate the lubricity oflubricant in hot rolling, the simulation testingmachine in the laboratory is modified from one for coldrolling. The evaluation performance of the simulationtesting machine is investigated into using the SPHCworkpiece strip having dimensions of a width of 20 mmand a thickness of 2 mm at a hot rolling temperatureof 1030℃. From the experimental results, the lubricityof lubricant in hot rolling can be evaluated by thecoefficient of friction measured. The effect of theadditive on the coefficient of friction can be alsoconfirmed. The obtained results are as follows: (I) When the mineral oil andone with oiliness additives are used as lubricants, thecoefficient of friction increases rapidly withincreasing rolling distance. (2) When the oils with theextreme-pressure additives are used the coefficient offriction is steady over a rolling distance of 1000 mm.