Abstract: A machine tool essentially comprises a chuck or workpiece holding assembly (S) for rotating a workpiece (W) about a revolution axis (X) of a surface to be obtained on the workpiece, and a rotary composite tool (22) having a series of elementary tools (32.sub.1 . . . 32.sub.6) located at angularly spaced apart positions about an axis of rotation for the composite tool; each elementary tool has respective front cutting edges (40) substantially radial relative to such an axis of rotation. The axis of rotation for the composite tool is orthogonal to a plane tangent to the surface to be obtained on the workpiece and the composite tool is movable relative to the workpiece parallel to such a plane. The consecutive front cutting edges are arranged on the composite tool at decreasing spacings from its axis of rotation, and at decreasing spacings from the workpiece surface. The farthest front cutting edge from the axis of rotation is also the farthest cutting edge from the tangent plane.

Abstract: Apparatus for the dynamic testing of a pair of meshing gear wheels by driving one and restraining the rotation of the other, in which the two gear wheels under test are held in mesh with one another and carried by separate rotary supports comprising pairs of aligned rotary spindles, having means for clamping a wheel under test between facing ends thereof, one spindle of each pair being axially displaceable to effect such clamping and the other spindle of each pair being connected to a rotary electrical machine which can function both as a motor and a brake; accelerometer transducers are mounted on the said one spindle of each pair to rotate therewith and thus with the wheels under test, the output signals from the transducers are fed via slip rings to processing circuits including means for summing and squaring them before passing the processed signals for display.

Abstract: Automatic control of the machining process of a series of workpieces is effected by a computer-controlled machine tool in which the feed speed of a cutting tool is controlled automatically according to a program determined in a preliminary teaching mode in which a sample workpiece is machined by a cutting tool advancing at a constant spaced speed and in which signals representing working torque on the tool for different positions of the tool relative to the workpiece, modified to take into account cutting characteristics, are stored in a memory. During a subsequent adaptive cutting mode the tool feed speed for machining successive workpieces of a series is determined by processing reference signals extracted from the memory with signals representing the actual thickness of the stock to be machined to generate a signal controlling the instantaneous rate of tool advance, taking into account tool wear parameters.