processing methods for numerically controlled machine tool and variable rotationsflaechen to processing such adjusted.

摘要

1. A process for forming evolutive surfaces of revolution, such as the lateral surfaces of internal combustion motor pistons, the generatrices of which are curved and the cross-sections of which are elliptical, by means of a tool-machine comprising a spindle (2) for rotating the work piece, a chuck (4) for holding the work piece and for indexing, and a work piece position detector (34), and further comprising a work table (9) guided in grooves parallel to the axis of the spindle, said table bearing a tool-holder assembly (10) which is transversely movable with respect to said axis, the position of the tool, with respect to the surface of revolution to be formed, being defined on the basis of the angle of rotation of said piece and the position of the tool along the said axis of rotation, and being adjusted by servo means controlling the relative position of the tool and the piece, said servo means comprising means for determining at every moment the value of angle A defining the angular position of the piece and, on the other hand, means for determining the longitudinal position Z of the tool-holder, characterized in that said servo means comprise an electronic computer which computes, in real time, the values of a function Fr (Z, A)=Fp Z+Fo (Z, A) the constants of which are previously determined, the functions Fp and Fo defining the curvatures of the profile and of the oval shape of the cross-section as a function of an axial co-ordinate Z and a reference angle A, while Fo (Z, A) is calculated by a reduced number of terms of a Fourier series of the type see diagramm : EP0043741,P10,F1 for values of Z which are previously determined, the output of the computer controlling, by means of a current of variable intensity, the motor which adjusts the position of the tool along its axis.