Development And Experimental Research Of An Indirect Sensor For Measuring Contact Stress During Cold Rolling With Inverse Method

The rolling mill of coupled vibration is a worldwide problem in the cold rolling process.Vertical vibration system and torsional vibration system are coupled with each other in the rolling interface.The contact stress at the roll gap is the key to establish a coupled vibration model.Therefore,how to predict the contact stress distribution accurately in the rolling interface is of important significance to improve the strip quality.Based on the theory of elasticity,an indirect sensor for measuring contact stress is designed.Using the idea of the envelopes fitting algorithms during the empirical mode decomposition(EMD),the inverse algorithm to calculate the contact stress is optimized and the prediction accuracy of the algorithm is improved.Applying the indirect sensor and the improved inverse algorithm,the contact stress is measured in the rolling interface under different process parameters at the experimental mill.The experimental resulted show that the torque corresponding to the integral value of the shear stress and the torque corresponding to the torque strain gage is closer than the previous literature results.The main research contents are shown as follows:(1)The error sources of the inverse algorithm and the selection criteria of the parameters based on the theory of elasticity were analyzed.Applying the idea of the envelopes fitting algorithms during EMD,the inverse algorithm was improved.The improved inverse algorithm was verified by means of numerical simulation.The results showed that the improved inverse algorithm was more accurate than before.(2)The sensor systems and the roll structure for measuring radial strain value and circumferential strain value in the rolling interface were designed.Sensor systems were calibrated,and the accurate calibration factors were obtained.On the basis of the above,the method to calculate the contact stress was derived by combining with improved inverse algorithm based on the radial strain value and circumferential strain value.(3)The indirect sensor was applied in the experimental mill,then the measurement of contact stress under different strip reduction ratio and interfacial friction condition were obtained.The results show that the greater the reduction ratio is and the more rough rolling interface is,the closer to the torque corresponding to the integral value of the shear stress and the torque corresponding to the torque strain gage is,and the smaller the error is.By combining theoretical and experimental methods,an indirect sensor for measuring contact stress during cold rolling was developed.The effectiveness and feasibility of the sensor were verified.It is of a certain reference value and guiding significance to the establishment of the rolling mill coupled vibration model.