ACCURACY OF INSTALLATION AND MACHINING OF BLANKS IN CAM ARBORS

The cam arbors are widely used for machining of axially symmetrical blanks with the medium and high radial stiffness. GOST 31.1066.04–97 is developed for cam arbors, but it lacks information on the accuracy of installation and machining of blanks on different metal-cutting machines, does not contain recommendations on engineering of such devices, and also contradicts other technical documentation and catalogues of western companies. In order to clarify such contradictions and to determine the data on the accuracy of cam arbors a number of articles are published. In the first article, which was published earlier, the consideration is given to deficiencies and contradictions to the mentioned GOST, and the material support for execution of complex investigations on the accuracy of installation and machining of blanks in cam arbors is described. The first part of this study is dedicated to the experimental investigations to determine the accuracy of installation of reference rings in the pilot samples of cam arbors with different design parameters. Upon analysis of the obtained data concerning the accuracy of installation the scope of experiments on the accuracy of machining of a batch of blanks in cam arbors was determined, methods of procedures were developed and the necessary pilot samples of fittings and other equipment were defined. The second part of the study is dedicated to the description of the results of experiments concerning the accuracy of turning and milling of blanks in different pilot samples of cam arbors. A batch of blanks (at least 30 blanks in a batch) with the same nominal parameters was machined during each experiment, then, the obtained results were processed by statistical methods. The third part of this study is dedicated to investigation of the precision reliability of cam arbors; to this end, a work bench was developed and manufactured which could make it possible to fix the pilot blank with the specified axial force, to hold it in the fixed state and to unfix. A number of cycles was brought to 200 thousand and it was determined that the cam arbors have the increased precision reliability.