Method for performing a screwing/unscrewing operation comprising a step of determining the maximum rebound speed of the rotor

A control device for controlling tightening torque applied by a screw driving device allowing to perform screw driving operations, said screw driving device comprising:

• an electric motor provided with a rotor;
• an output member capable of being rotated;
• a rebounding impact mechanism rigidly connected to said rotor and to said output member,
• said control device comprising:
• a controller configured to control the power supply of said motor to induce driving said impact mechanism by said rotor and periodically rotate said output member by said impact mechanism, the driving of said impact mechanism generating a plurality of successive impacts at an end of each of which said rotor rotates in a rebound in the opposite direction to the screw driving operation,
• means for determining a maximum rotational frequency reached by said rotor during the rebound following each of said impacts in said impact mechanism, and
• a controller configured to generate stoppage of a screw driving operation in progress when said maximum rotational frequency reaches a predetermined threshold corresponding to a predetermined tightening torque level,
• wherein said means for determining said maximum rotational frequency reached by said rotor during the rebound of said rotor comprise means for extracting and/or calculating physical quantities from said controller configured to control the power supply of said motor, said means for determining said maximum rotational frequency reached by said rotor during the rebound of said rotor being configured to determine said maximum rotational frequency taking into account said extracted and/or calculated physical quantities.

A screw driving device comprising:

• an electric motor provided with a rotor;
• an output member capable of being rotated;
• a rebounding impact mechanism rigidly connected to said rotor and to said output member;
• and
• a control device comprising:
• a controller configured to control the power supply of said motor able to induce driving said impact mechanism by said rotor and periodically rotating said output member by said impact mechanism, the driving of said impact mechanism generating a plurality of successive impacts at an end of each of which said rotor rotates in a rebound in the opposite direction to the screw driving operation,
• means for determining a maximum rotational frequency reached by said rotor during the rebound following each of said impacts in said impact mechanism, and
• a controller configured to generate stoppage of a screw driving operation in progress when said maximum rotational frequency reaches a predetermined threshold corresponding to a predetermined tightening torque level,
• wherein said means for determining said maximum rotational frequency reached by said rotor during the rebound of said rotor comprise means for extracting and/or calculating physical quantities from said controller configured to control the power supply of said motor, said means for determining said maximum rotational frequency reached by said rotor during the rebound of said rotor being configured to determine said maximum rotational frequency taking into account said extracted and/or calculated physical quantities.

A non-transitory computer readable medium comprising a computer program product stored thereon comprising code instructions which when executed by a computer of a control device configure the control device execute a method of controlling tightening torque applied during a screw driving operation by a screw driving device comprising:

• an electric motor provided with a rotor;
• an output member capable of being rotated;
• a rebounding impact mechanism rigidly connected to said rotor and to said output member,
• said method comprising:
• supplying said motor with power inducing driving said impact mechanism by said rotor and periodically rotating said output member by said impact mechanism,
• the driving of said impact mechanism generating a plurality of successive impacts at an end of each of which said rotor rotates in a rebound in the opposite direction to the screw driving operation,
• determining a maximum rotational frequency reached by said rotor during the rebound following each of said impacts in said impact mechanism, and
• stopping said screw driving operation when said maximum rotational frequency reaches a predetermined threshold corresponding to a predetermined tightening torque level,
• wherein supplying said motor with power comprises using a controller to control the supply power to the motor, said determining said maximum rebound rotational frequency reached by said rotor during the rebound of said rotor comprising:
• extracting and/or calculating physical quantities from said controller, and
• determining said maximum rebound rotational frequency reached by said rotor during the rebound of said rotor taking into account said extracted and/or calculated physical quantities.