A split cam design is proposed to solve the problem of assembly of the single piece cam in the flexible raced bearing of an earlier proposed novel harmonic drive system, which shows better torque characteristics and capacities in comparison to the conventional one of same size with oval-shaped strain wave generating cam. The cam profile has circular arcs at two working zones at 180° phases. The proposed profile shape is identified as the cause of trouble in assembly if the cam is made single piece. The split cam is made of two identical pieces having circular arc edges. These pieces constitute the cam in assembly after putting it inside the inner race of the flex bearing and adjusted by an adjuster. The design, kinematics, and the assembly method of the proposed split cam are presented in this article. The split cam arrangement not only solves the assembly problem but also gives a scope of fine adjustment of center distance (eccentricity). Such an adjustment is not possible in conventional oval wave generating cam. Stresses in flex gear cups assembled with both type cams at load and no-load conditions are estimated using finite element method. Some results are verified experimentally. Although the flex gear cup with the proposed split cam experiences lower stresses at load transmitting active gear contact zones, it shows higher stresses at some non-active zones (where teeth are free of load). It is apparent from results that stresses at those non-active zones do not increase substantially with the increase in torque, as they are away from active zones.
ELID Grinding, since its introduction over two decades ago, has helped in material removal of hard and difficult-to-cut engineering materials. A gist of the important research milestones on the process has been organized in this report. The hybrid process of ELID Grinding has a simultaneous electrolytic reaction and grinding action. Electrolysis takes place between the conductive anodic wheel and highly conductive cathode in presence of a special electrolyte. The resulting anodic oxide wears off easily to allow efficient grinding. The different parameters involved in electrolysis complicate the mechanism of grinding and makes it significantly different from conventional grinding. Different variants of the process have also been reported, though the basic philosophy of operation is the same as basic ELID. Several authors have also suggested mathematical explanations, among other fundamental studies, that provide further insight. The basic components of the process, machine tool, power supply, grinding wheel, electrode and electrolytes, have also undergone several modifications and developments to deliver better results and suit specific purposes. The process has been successfully applied in stock removal operations for hard and brittle ceramic materials with low grinding forces compared to conventional grinding. Fine finishing of almost all kinds of hard and brittle materials, ranging from hardened steels, BK7 glass, mono-crystalline silicon, silicon carbide, aluminum nitride, silicon nitride etc, has been successfully carried out, to provide high quality surfaces with low sub-surface damage. Finally, discussions on the different stages of evolution of the process have been put forward as a conclusion to the report.
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