plates 4a 4b respectively on which tools and accessories may be mounted beforehand outside the press lower chucking plate 2 acting as the ram of the press e g a precision blanking press is at bottom dead center which means that the seat height always remains constant even if the tool height h is not the same in fig6 lower tool part 3b with its lower auxiliary plate 4b is shown already clamped to lower chucking plate 2 this is achieved by pushing clamp bars 18 secured to the bottom of lower auxiliary plate 4b into matching slots 5 of lower chucking plate 2 and clamping them tight by means of four grippers 8 provided in lower chucking plate 2 the clamping action of lower grippers 8 as set forth below is triggered by proximity switch 16a in stop 16 when the inserted tool set 3 comes up against the latter the clamping force is transmitted via clamp bars 18 to lower auxiliary plate 4b or to lower tool part 3b both in chucking plates 1 2 and in upper tool part 3a and lower tool part 3b or in auxiliary plates 4a 4b secured thereto two parallel t slots 5 6 each are provided disposed in each chucking plate 1 2 are four grippers 8 which are likewise provided with t slots 7 continuously aligned with t slots 5 of chucking plates 1 2 grippers 8 integrated in chucking plates 1 2 may be operated hydraulically or mechanically or hydromechanically upon actuation of the proximity switches associated therewith in a manner well known in the art such as by the above mentioned proximity switch 16a which controls the lower grippers 8 or the proximity switch 17 which controls the upper grippers as set forth below each.