Abstract: A tightening method yielding a precise control of the resulting clamping force, in which the tightening operation is performed in two steps, and the stress level is always kept within the limits of the elastic portion of the stress×strain curve. The method employs a single or multi-spindle power wrench controlled by a computer, provided with measuring means for the precise sensing of applied torque and turn angle in real time. The method comprises in a preferred embodiment a first and a second tightening operations, the data collected during the first operation being inputted to the computer which calculates the amount of torque to be applied to the fastener in the second and final tightening operation according to an algorithm which also comprises checking steps to ascertain that the results fall within the preset values, tolerances and scatter limits.

Abstract: A tightening method yielding a precise control of the resulting clamping force, in which the tightening operation is performed in two steps, and the stress level is always kept within the limits of the elastic portion of the stress×strain curve. The method employs a single or multi-spindle power wrench controlled by a computer, provided with measuring means for the precise sensing of applied torque and turn angle in real time. The method comprises in a preferred embodiment a first and a second tightening operations, the data collected during the first operation being inputted to the computer which calculates the amount of torque to be applied to the fastener in the second and final tightening operation according to an algorithm which also comprises checking steps to ascertain that the results fall within the preset values, tolerances and scatter limits.

Abstract: METHOD FOR ATTAINING A PREDETERMINED CLAMPING FORCE IN THREADED JOINTS through the employment of a plurality of equations and graphs converted into digital data and applied to a system of intelligent monitoring, being part of a computer program or specific software dedicated to operate manual or automatic spindle machines, the needed parameters being measured at the axle of the equipment connected to the wrench that acts over a threaded fastener, such as a bolt, nuts or equivalent element during the fastening operation, the acquisition of the data for calculation and utilization the variable “torsion angle” ?, ?t and ?t?? occurring in real time during the operation of pretightening untightening and retightening performed by the spindle, said “torsion angle” ?, ?t and ?t?? being extracted from parameters of torque and displacement necessary to obtain the clamping force of the jointed parts (plates and fastener) that are acting cooperatively during the tightening operation, said torsion angle ?, ?t and ?t? taki