GB1328375A - Metrology spindles - Google Patents

Abstract

1328375 Bearings J GOULDER & SONS Ltd 18 Aug 1971 [20 Aug 1970] 40215/70 Heading F2A A spindle of a metrology machine which supports a workpiece, is mounted in a sleeve to which gas is supplied through openings 21 to form a gas bearing, the spindle being located axially by a gas thrust bearing 30 which is movable axially by means of a rotatable lead screw which is coaxial with the spindle and which engages with a nut connected with the stator of the thrust bearing by a coupling which prevents relative axial movement of the nut and stator while permitting relative rocking about mutually perpendicular axes transverse to the axis of rotation. The coupling may comprise three annular washers having between each pair two rollers 49, 50 forming fulcra between the middle washer and each of the outer two, the axes of the fulcra being mutually perpendicular. The coupling may also include a ball thrust bearing 51 which permits relative radial or orbital movement, and the bearing surface of the thrust bearing may be allowed to pivot relative to the rest of the stator, e.g. by means of a deep groove ball bearing 33. Air is supplied to the thrust bearing via a ring of ports 32 in the thrust plate 35, from an annular groove 34. The thrust bearing is carried in the machine on a crosshead 27 which slides on guide rods 25 parallel to the axis of rotation of the spindle. Rotation of the nut during movement of the crosshead is prevented by an arm 58 carried by the nut which engages with a vertical post 59 in the machine.