Thermal error prediction model method for electric spindle with variable bearing pre-tightening force

The invention discloses a thermal error prediction model method for an electric spindle with variable bearing pre-tightening force, which comprises the following steps: constructing an electric spindle temperature field model, and analyzing the temperature of a heat source and the temperature of a key component; establishing a motorized spindle statics finite element model by using different pretightening force conditions and spindle component parameters changed due to temperature change under the conditions, and analyzing the relationship between the thermal error of the motorized spindle and the pretightening force and the temperature; establishing a grey wolf optimization algorithm (GWO) model, adopting a mode of randomly generating a grey wolf population, initializing positions of alpha, beta and delta wolf of a grey wolf pack, globally searching a fitness optimal value of each body of the wolf pack, and searching a penalty factor (C) and a kernel function width (g) of a support vector regression (SVM) mo