Abstract: The invention concerns a process and an apparatus for measuring the anisotropy value of form changes in normal direction in sheet metals (the r-value). In course of a standard tensile test, the longitudinal change of dimension of the test piece is measured. When a preselected value of change of dimension in longitudinal direction which is characteristic of the material of the test piece, is reacted during the measuring process, the appertaining change of dimension in lateral direction is measured. Thereafter, an r-value is selected from the r-values corresponding to different changes in dimension in lateral direction at a preselected longitudinal change of dimension, which is closest to the one measured at the change of direction in lateral direction. The apparatus comprises comparator and switching units which are connected to signal transmitters converting changes of dimension in longitudinal direction into electric signals.

Abstract: A method of and apparatus for the determination of the standard tensile yield point in which the extension of a test body is monitored, comprises determining in the course of continuous extension within the elastic limit, the ratio of the instantaneous extension and the associated load, storing this ratio and in the course of further continuous extension the ratios of a given residual extension as well as that of the instantaneous extension and the instantaneous load are determined, the stored ratio value is summed with the ratio of the given residual extension and the instantaneous load, and the thus obtained sum is compared with the ratio of the instantaneous load whereby the instantaneous load at which the compared values become substantially equal gives the tensile yield stress at the given residual.

Abstract: A workpiece clamping device for the fast, central clamping of workpieces provided with holes of various number and pitch diameter and/or with a central hole, such device being adapted for the balancing of vehicle wheels. The device consists of a fixing mechanism, releasing mechanism and a clamping unit attachable to them with the workpiece. The clamping unit contains a central mandrel with a threaded end, a pressure element movable on the mandrel in an axial direction and secured against turning with respect thereto, and one or more locating elements connected to the pressure element and fitting into the hole or holes of the workpiece as well as a threaded clamping element supported by the pressure element. The fixing mechanism contains a sleeve receiving the mandrel of the clamping unit; the fixing device is provided with a selectively operated releasing mechanism. Operation of the releasing mechanism automatically disables the motor which drives the balancing mechanism.