INVESTIGATING THE INFLUENCE OF CAPILLARY TUBE GEOMETRY ON HYDROSTATIC HEAD PRESSURE USING NUMERICAL SIMULATIONS

Abstract

The spindle unit is a critical component in machine tools, responsible for driving and transmitting power to the cutting tool while ensuring machining accuracy.
Research and development of advanced technologies for spindle assemblies are essential to enhance performance and precision in mechanical processing. Hydrostatic
bearings, which use liquid to reduce friction and wear, offer high accuracy and load-bearing capacity, and are widely used in applications requiring high precision. This
study analyzes the impact of capillary tube geometry on the pressure in hydrostatic bearings using numerical simulation methods. Results indicate that the pressure
ratio between the oil chamber and the pump decreases as the lc/dc ratio increases, and β increases with the capillary tube diameter dc. Within the capillary diameter
range of 0.3mm to 0.6mm, an appropriate lc/dc ratio can be selected to meet the requirement of 0.4 < β < 0.7. The oil film formation mechanism through capillary tubes
shows that the geometric parameters of the capillary tube directly affect the pressure ratio between the oil chamber and the pump, ensuring operational conditions,
particularly the bearing clearance limits. The pairs of capillary diameter and capillary ratio (dc; lc/dc) corresponding to (0.3; 33), (0.4; 78), (0.5; 152), (0.6; 200) are
identified as suitable to maintain the bearing clearance within permissible limits. This research contributes to a deeper understanding of the influence of capillary tube
geometry on the performance of hydrostatic bearings. The findings can be used to design and optimize more efficient hydrostatic bearing systems, especially in high-
precision applications such as external cylindrical grinding machines.