System and method for the quality control of screwed-in joints

A method for the quality control of screwed-in joints, comprising the phases consisting in:

• a) providing a system comprising:
• an electronic dynamometric wrench comprising a lever body (2) provided, at one end, with a handle (3) and, at the opposite end, with a coupling head (4) with the threaded tightening element of the joint to be controlled, sensor means (6) of the torque applied to said threaded tightening element which are associated with said lever body (2) and which are suitable for supplying an output signal corresponding to the torque applied to the threaded tightening element from said lever body and sensor means (7) of the rotation angle of said lever body (2) which are associated with said lever body and which are suitable for supplying an output signal corresponding to the rotation angle of said lever body when applying said torque,
• first interface means (12, 13) with an user which are associated with said lever body and which comprise signalling means,
• a processing unit (9) in communication with said sensor means (6) of the torque and said sensor means (7) of the rotation angle of said lever body (2), from which it receives in input the respective output signals, and with said first interface means with a user,
• b) applying, by means of said dynamometric wrench, a torque to the threaded lightening element of a joint to be controlled in the rotation direction corresponding to the tightening of the same and acquiring, through said sensor means (6, 7), the values of applied torque (Ti) and of the corresponding rotation angle (Ai) of said lever body,
• c) identifying, among the pairs of values consisting of torque and corresponding rotation angle of the lever body acquired from said respective sensor means, the pair of values corresponding to the moment when said threaded tightening element begins to move,
• d) discriminating, among the pairs of values subsequent to and comprising the pair of values of the start of the movement so identified and comprised in a predefinable variability range of said rotation angle of said lever body, the pair of values consisting of the residual torque and the corresponding rotation angle of said lever body, and
• e) signalling to a user the detection of the pair of values consisting of the residual torque and the corresponding rotation angle of said lever body through said first signalling means.