AXIAL LOAD-CAPACITY OF WATER-LUBRICATED HYDROSTATIC CONICAL BEARINGS WITH SPIRAL GROOVES (ON THE CASE OF RIGID SURFACE BEARINGS)

This paper describes the static characteristics of water-lubricated hy drostatic conical bearings with spiral grooves. Hydrostatic conical be arings treated here have been designed for high speed spindles and are intended to apply to spindles for drilling small holes of printed cir cuit-boards, Pressurized water is first fed to the inside of the rotat ing shaft and supplied to spiral grooves on the shaft surface through feeding holes. Therefore, water pressure is greatly increased at outle ts of feeding holes due to the centrifugal force by shaft rotation. Fu rthermore, water pressure is also increased by the viscous pump effect of spiral grooves. Water pressures in the bearings under concentric c ondition are numerically obtained by using the finite element method a nd calculated results are compared with experimental ones. It is conse quently found that this water-lubricated hydrostatic conical bearings with spiral grooves are very suitable for precision high speed spindle s.