The high stiffness is required to reduce the relative displacement between workpiece and cutting tool due to the cutting force even for ultra-precision machine tools. From the viewpoint of the strucuture with high stiffness, a gate-type structure is desirable. However, it is in general difficult to construct, and is liable to large size. In terms of easiness of construction, a lathe-type ultra-precision milling machine was already made together with a pseude ball endmill of single crytal diamond as a cutting tool. The study deals with the further improvement of stiffness by upgrading the lathe-type ultra-precision milling machine to that with a closed- loop structure. Thus, two constraint axes are employed to form the closed-loop structure, and are able to move in cooperation with x- and z-axis movements by the newly developed control software. The effect of the closed-loop structure is experimentally confirmed as well as FEM analysis.
Keywords: Ulrtra-precision machining center, Closed-loop structure,Constraint axis, High stiffness
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1996/11/02, by H.Watanabe