System for Compensating the Rigidity of the Hydrostatic Guideways of the Column Saddle Subassembly of the Boring and Milling Machines

Abstract

The improvement of the machining accuracy of boring and milling machines is imposed by the more and more demanding conditions on the accuracy of the work pieces to be machined. The specificity of this family, of boring and milling machines, consists of the horizontal motion of the milling spindle (quill) with implications on the application point of the gravity center. Thus, the variation of the application point of the sum of the component elements weights of the column saddle subassembly leads to modifications of the oil film thickness in the hydrostatic guideways, affecting the geometrical accuracy of the machine. This work is presenting a system of compensation and hydrostatic guiding of the column saddle subassembly. This new compensation system allows the pressure in the pockets to be modified by taking in consideration the position of the application point of the weight of the entire column saddle subassembly. The implementation of this compensation and guiding system on the boring and milling machine model AFP 220 has led to an increasing of two times the geometrical accuracy of the horizontality of the column saddle`s motion, compared to the variant without compensation.