Abstract: A method for positioning operative cylinders, for example of rolling-mills or paper-mills on a grinding machine, includes at least the following steps: A—positioning the transversal, longitudinal center-line plane of the cylinder in correspondence with a reference point situated between a movable piece-holder head and tailstock center of the machine; B—moving the piece-holder head and the tailstock center in the direction of the cylinder until there is a reciprocal coupling. The present invention relates also to a machine for implementing the above method.

Abstract: A protection device for a grinding wheel includes a containment structure having an operating opening for a grinding wheel, wherein the containment structure includes a fixed portion and a movable portion which can be moved with respect to the fixed portion by means of a motor and which can be blocked with respect to the first fixed portion by means of a magnetic blocking unit. The device further includes a sensor adapted to automatically detect the position of the movable portion, and a control means of the entire device.