Patent GB-497695-A (GB)
Title: Improvements in or relating to spindle mounting for boring, grinding and like machines
IPC: B23B29/034
Filed: 1938-01-11
Abstract: 497,695. Bearings. HEALD MACHINE CO. Jan. 11, 1938, No. 893. Convention date, May 14, 1937. [Class 12 (i)] [Also in Groups XXII and XXIII] In a spindle mounting for a boring, grinding or like machine the spindle is rotatable in bearings in a head with slight lateral play and means are provided, operative only when the spindle is at rest, for applying lateral pressure to move the spindle in a predetermined radial direction in the bearings, without any longitudinal movement, in order to relieve the tool from the work prior to withdrawal therefrom. The spindle 2 carrying a cutter 9 secured by a screw 10 is mounted in a head 1 in bearings 3, 4 of the rocking shoe or Michell type. The bearing 3 comprises three shoes 11, 11a, Fig. 2, having inner surfaces of less curvature than the spindle and outer surfaces of greater curvature than the interior of the head, the shoes 11 being pivotally secured by pins 13 and the shoe 11 a being pivotally mounted on a pin 19 attached to an adjustable screw 16. The inner surfaces of the shoes have steps 21 parallel to the end surfaces 22 to increase the pressure of the oil film. The bearing 4 comprises three shoes 23, 23a which are floatingly held by three axially arranged arms 26 carried by two rings 25, Fig. 1, loose on the spindle. The shoe 23a is adjustable by a plug 27 which may be moved radially by the bevelled end of a plunger 28 and a screw 30, and the shoes may be rotatably adjusted to position them opposite enlargements 32 of the bore in the head 1 in order to give greater lateral clearance to the spindle. This adjustment is effected by a plunger 35, Fig. 3, having a recess 33 engaging a gear tooth on one of the arms 26 and normally pressed upwards by a spring 36. When rotation of the spindle 2 is stopped and a hydraulic brake is applied, a pipe 62 leading from the brake cylinder conducts fluid to lift a plunger 61 and raise the pressure of the lubricating oil which is supplied by a pump 50 to the bearings 3, 4. This higher pressure is admitted to the interior of the plunger 35 through the recess 33 and depresses the plunger, thereby rotating the arms 26 and shoes 23, 23a to position the latter opposite the enlargements 32. The spindle is moved laterally when its rotation is stopped, to remove the cutter from the work, by a lever 53, Fig. 1, pivoted at 54 in a sleeve 51 secured to the spindle. One end of the lever engages a ring 56 rotatably mounted in the head 1 and connected to the sleeve by a pin 59, and is normally pressed against the ring by a spring 55 to move the spindle laterally. During rotation of the spindle, however. centrifugal action on the lever releases it from the ring and allows the spindle to rotate centrally for cutting, and only when rotation stops is the spring 55 allowed to act. Oil is retained in the bearings by a ring 38 retained between a shoulder 39 on the spindle and an end surface of the head 1, and a ring 44 engaging the other end surface of the head. Springs 43 in a collar 40 splined to the spindle engage a flange 42 attached to the spindle to press the latter rearwardly and maintain the rings 38, 44 in contact with the head. Oil leaking from the bearings and plunger 35 is drained by passages 46, 64 and 47. The work or the boring head may be fed axially, and the spindle 2 may carry either the tool or the work. Specification 500,907 is referred to.