Mass measurement apparatus for automatic processing machines and mass measurement method

A mass measuring apparatus associable with an automatic processing machine for measuring mass of articles or parts thereof, processed by the automatic processing machine that comprises at least one movement device provided with seats for housing and moving the articles, the mass measuring apparatus comprising:

• a transferring and gripping device arranged to remove an article or part thereof from a respective seat of the movement device, hold the article or part thereof in a measuring position and then reinsert the article or part thereof into the respective seat, said transferring and gripping device comprising at least one gripping element adapted to hold the article or part thereof in the measuring position;
• an actuator assembly arranged to operate with an actuating signal on said gripping element for making said gripping element vibrate alone at a specific resonance frequency;
• a sensor system configured for measuring a vibration response signal of said gripping element vibrating and supporting the article or part thereof in the measuring position;
• and
• a processing unit connected to said sensor system and arranged to receive the vibration response signal and to control said actuator assembly in order to:
• generate an actuating signal of said actuator assembly able to make said gripping element supporting the article or part thereof vibrate at an operating resonance frequency and then calculate a mass of the article or part thereof by comparing the operating resonance frequency with the specific resonance frequency of said gripping element;
• or alternatively
• generate an actuating signal of said actuator assembly able to make said gripping element supporting the article or part thereof vibrate at the specific resonance frequency of said gripping element and calculate a mass of the article or part thereof by measuring an operating phase difference between the actuating signal of said actuator assembly and the vibration response signal detected by said sensor system.