Abstract: The handpiece-type high-frequency vibration apparatus includes a roughly cylindrical housing 10 configuring a handpiece, a holding member 11, a tool 12, a controller 20 and an excitation device 21. In a non-contact state before the tool 12 is brought into contact with an object, the controller 20 drives the excitation device 21 so as to vibrate the tool 12 at an added frequency fp for which a predetermined frequency fs is added to a first resonance frequency fr1 of the tool 12. In a cutting state where the tool 12 is in contact with the object by a load that enables cutting of the object by the tool 12, the controller 20 controls drive of the excitation device 21 such that a third resonance frequency fr3 of the tool 12 increases and coincides with the added frequency fp, and increases a vibration frequency of the tool 12.

Abstract: A CNC process for displacing a movable member along a path on an intricate surface in a three-dimensional coordinate system is disclosed in which the surface is divided into a plurality of elementary characteristic regions each individually definable as one of different geometrical categories such as toroidal, spherical, cylindrical and planar surfaces. The process comprises establishing a general equation for each of these categories and storing the established general equations into a memory unit for a computer. Data required to adapt each of the stored general equations to a corresponding one of the characteristic regions in the three-dimensional coordinate system are inputted into the computer to reduce the general equations to their respective specific equations in which no more than three coordinates are variable.

Abstract: A numerical-control (NC) method and system for machining a desired three-dimensional contour in a workpiece with an axial tool, e.g. a rotary milling cutter or electroerosion electrode, formed at its axial end with an active machining surface which is spherical about a center intersected by the axis of the tool. According to the invention, numerical coordinate values for the positions of this center of the tool to be displaced relative to the workpiece need not to be preprogrammed and stored on a record medium.

Abstract: A method of controlling electrical discharge machining in which a machining discharge is initiated and the particular geometric characteristic of the site of the discharge is ascertained by detecting at least one of the gap variables over a predetermined checking period of the discharge and evaluated with respect to a reference value. A parameter of the discharge, e.g. duration and/or current magnitude is established at a particular value preset to correspond to a particular geometric characteristic and the discharge is terminated in accordance with the regulated parameter.