Simultaneous Inspection and Correction of Gears in Production 280062
BY means of the gear-correcting process described, spur and helical gears are corrected to give a high degree of uniformity in spacing and profile so that the gears become practically interchangeable. They acquire a “crown face” which enables them to run with unusual quietness under practical conditions. This is essentially an inspection-correction process, as it automatically finds and eliminates the errors.
The lap is the important item in the process. It is of chilled cast-iron, gray cast-iron, or type metal, and is made by casting in a mold around a steel chill cut to approximate the gear to be corrected but has a face-width several times that of the gear. The lap, when completed, looks like a wide-faced internal gear.
The gear-correcting machine is of relatively simple construction and performs three main functions: (a) it provides reciprocating motion for the gear; (b) it causes mutual pressure between the faces of the gear teeth and the lap; (c) it advances the gear one tooth with respect to the lap at the completion of every cycle so as to assure uniformity of spacing and contour.
Unlike the many instruments and methods that have been devised for merely detecting errors in gears, the authors state that the so-called inspector-corrector device not only inspects the gears but also corrects them after all other operations, including heat-treating. Further, they assert that the device will do this work without adding to the total cost of gears, for the feeds of gear-cutting machines can be increased to compensate for the time required by the gear-correcting operation. The resultant gears will be interchangeable, and will eliminate virtually all matching-up, as well as rejections in the final tests.
In the discussion, a further description is given of how the conjugate tooth-form of gear and lap is obtained, and additional details of so-called “multiple-series” lapping are presented.