Online measuring and estimating methods for the unbalancing vector of thin-disc workpiece based on the adaptive influence coefficient

Abstract

The thin-disc part is the common part of the rotary mechanism. Because of the large rotating radius of the thin-disc part, the huge unbalancing vector may be formed even if the unbalancing mass is small. So, the unbalance of the thin-disc part is the important exciting factor of the rotary mechanism vibration. Based on the structural characteristics of the thin-disc part, the measuring and estimating methods for the unbalancing vector of the thin-disc workpiece are proposed based on the single-face influence coefficient method. The least square method is introduced to fit the fundamental frequency component from the vibration monitoring signal, and the fundamental frequency component is taken as the unbalancing vibration signal of spindle first. The influence coefficient between the trial weight face and vibration monitoring point on the spindle is tested by trial weight experiments second. The unbalancing vibration difference of the spindle, before and after the thin-disc workpiece is clamped, is monitored and used to estimate the unbalancing vector of the thin-disc workpiece based on the linear reversible principle of unbalancing excitation and vibration response. The signal separation accuracy of the least square method for unbalancing vibration has been proved by simulation and experiment methods. Considering that the accuracy of the influence coefficient may be influenced by the change of the spindle system kinetic characteristic parameters, the signal measurement, analysis error, etc., the adaptive method for the influence coefficient is proposed and proved by the experiment method in the article. The research results show that the unbalancing vector of the thin-disc workpiece can be measured and estimated before the workpiece is taken down from the machine tool spindle. The proposed method can be used to measure and estimate the unbalancing vector of the thin-disc workpiece without dynamic balancing machine, and the measuring efficiency and accuracy can be improved; the measuring cost can be reduced.