A METHOD OF MILLING AND AN ABRASIVE MILLING HEAD FOR NUMERICALLY CONTROLLED APPARATUS

摘要

1,217,789. Grinding. CORNING GLASS WORKS. 21 Aug., 1968 [22 Aug., 1967], No. 39904/68. Heading B3D. A head for abrasively milling a curved surface 14a on a workpiece 14 and adapted for attachment to a milling machine which is controlled by numerically controlled signals and has a work-table for supporting the workpiece comprises an endless abrasive belt 55 which is driven by a motor 40 about a plurality of rollers 18, 19, 20, 21 and a wheel 42, the wheel having the configuration of the centre segment of a sphere, and means 29 acting on one of the rollers to apply tension to the belt. The workpiece may be a plunger used for press forming glass viewing panels, such as television tubes. The hand consists of a pair of plates 16, 16f which are secured to the machine 11 by bolts 17. The plates carry a bracket 23 for roller 18, a slide 26 for a bracket 24 which carries roller 19 and can be moved by a fluid pressure cylinder 29 to tension the belt, a bracket 34 for a pivot 33 secured to a bracket 32 which carries the roller 32 and is adjustable by a screw 37 about the axis of the pivot to adjust the tracking of the belt, and the motor 40 for driving roller 21 for imparting drive to the belt. The plates also carry a block 45 in which is a pivot 44 carrying a bracket 44 for the wheel 42, the pivot being clampable in adjusted position by nut 44d. The outer rim of the wheel 42 may be provided with a slightly resilient tyre and is in the form of the centre portion of a sphere so that during the forming of the curved surface 14a on the workpiece, the belt always makes tangential contact with said surface. Either the hand or the worktable may be moved in three dimensions in at continuous path by a unit 10 of a numerical control system.