HYDROSTATIC SEAL FOR MACHINE TOOL SPINDLES

1367973 Milling machines; machine tool details GIDDINGS & LEWIS Inc 11 Jan 1972 [13 Jan 1971] 1129/72 Headings B3B and B3K [Also in Division F2] A contour milling machine 10, Fig. 1, is provided with a swivel base 17 and a swivel saddle 20 which supports a headstock 11 carrying a cutting tool 23, the movements of the headstock and tool being numerically controlled. As shown in Fig. 2, the headstock 11 consists of a spindle 34 which is mounted by bearings 35, 36 in a cylindrical quill 32 supported within a housing 30, the bearings being preloaded by an annular piston 39 and supplied with cooled lubricating oil through passages 43 and 44. The spindle is driven by a bull gear 37 and sealed by a hydrostatic seal 45 (Division F2) to which compressed air is supplied through passages 57. The seal of the invention can also be applied to spindles which both rotate and move axially such as in machines for drilling, boring or tapping. In Fig. 7 (not shown) the spindle is mounted in hydrostatic bearings (93) for such rotary and axial movement.