6) A tapered surface is to be turned on an automatic lathe. Thework piece is 900 mm long with minimum and maximum diameters of 150mm and 300 mm at opposite ends. The automatic controls on the lathepermit the surface speed to be maintained at a constant value of200 m/min by adjusting the rotational speed as a function of workpiece diameter. Feed=0.25 mm/rev and depth of cut = 3.5 mm. Therough geometry of the piece has already been formed, and thisoperation will be the final cut. Determine (a) the time required toturn the taper and (b) the rotational speeds at the beginning andend of the cut. (c) Suppose that the automatic lathe surface speedis not available and a conventional lathe must be used. Determinethe rotational speed that would be required to complete the job inexactly the same time as in part (a) of the problem.
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