| 摘要 |
1296011 Machining commutators AMDEK CORP 1 Jan 1971 43/71 Headings B3B and B3K A method of machining a surface of a rotatable workpiece having electrically conductive and non-conductive zones on said surface, e.g. a commutator 25 of an armature 21, or on a template connected to the workpiece, comprises demountably securing the workpiece for rotation in V-bearings 23, 24 by a load applied by a flexable belt which also frictionally rotates the workpiece in the bearings; electrically probing the surface to be machined, or the surface of the template, whilst it is rotated to detect a boundary between a conductive and non-conductive zone; arresting the rotation of the workpiece by stopping the belt when a boundary is detected; performing a first machining operation; and then either, repeating the previous steps to perform subsequent machining operations; or, performing subsequent machining operation at predetermined locations on the said surface when the belt stops the drive to the workpiece. Apparatus for performing the method comprises a rotary cutter driven by a motor 33 and movable relative to the armature by a carriage 34; yieldable indexing means for indexing the armature comprising a stepping motor and pulleys 37, 38, 39 for the belt; and control means. The control means includes a radio frequency probe switch 47 having a single point probe riding in intimate contact with the commutator surface to sense each successive insulative slot and to halt the rotaty indexing of the armature for an undercutting operation, and to signal said indexing means to recommence rotation of the armature after completion of an undercutting operation. The V bearings and the yieldable drive permit the armature to move slightly under the influence of the rotary cutter to allow a slightly askew slot to be cut. The armature is freely mounted in the V bearings without any clamps &c., and a lower run of the belt 37 engages the surface of the armature to yieldingly index it in minute, discrete increments. In machining a new commutator the blank has a template mounted on its end that includes the electrically conductive and non-conductive zones (Fig. 4, not shown). |
