Study on Precision Machine Table Equipped with Constant-Flow Hydrostatic Water Bearings

Abstract

In order to realize environmental-friendly machine tools, a linear-motor-driven table supported by constant-flow hydrostatic water bearings is developed. The table system is free from environmental pollution because the system needs no oil. For simplicity, a single-sided bearing system is chosen for the table-slide. To obtain a high sustaining force, preload is applied to the bearings using the attractive force of an iron core linear-motor’s magnets. The preload is effective in both the vertical and horizontal directions by inclined motor magnets. Miniature gear-pumps supply flow to the bearings without pump pulsation, and the bearings consume very small amounts of water and electric power. The measured table sustaining force was 3.0kN and static stiffness was 0.3kN/m under a flow rate Q=0.92mL/s per bearing and ideal bearing clearance h=16m.