Method for screwing a ring nut of a trigger pump on a container and apparatus

A method for screwing a ring nut of a trigger-shaped (5) pump or trigger (1) on a vessel (6), the pump or trigger (1) being provided with a dip pipe (4), i.e. a small pipe intended to be inserted within the vessel, an externally-toothed ring nut (2) which is free to rotate relative to the body (8) of the pump and is innerly threaded (3) to be associated with the corresponding threading provided on the neck of the vessel to be capped;

• said capping being carried out by means of a head (10) for gripping and screwing the ring nut (2), characterized in that it provides to:
• a. grip said trigger-pump or trigger (1) by means of lever-type clamping means (11) by locking the ring nut (2) therebetween thereby making the latter integral therewith;
• said grip being carried out by positioning the trigger (5) out of the overall dimensions of the gripping-levers;
• b. rotate by means of a motor drive (16), the grippers (11) and the ring nut (2) integral therewith after the latter is at the respective container threaded mouth;
• c. screw the ring nut (2) on the container threaded mouth and screw it to the body until the screwing torque has reached a preset value, thereafter the connection with the motor drive (16) of the gripping unit is stopped;
• d. carry out a first detachment of the clamping means from the respective ring nut;
• said operation being the minimum required to avoid any contact therebetween;
• e. rotate the clamping means (11) by means of the motor drive (16) associated therewith, and place them back to their original configuration, i.e. by placing the trigger out of the overall dimensions of the gripping levers;
• f. carry out a further opening of the clamping means from the respective ring nut (2);
• said operation being the minimum required to open the gripper completely and release the trigger.