High-precision tensioning device

A high-precision tensioning device, comprising a stepping motor, an encoder, a harmonic reducer, a rotary table, connecting rods, contacts, force sensors, a rotary table connecting piece, a gasket, a nut, bolts, a set screw, a shell and an end cover, wherein a back end of the stepping motor is connected with the encoder, and an output end of the stepping motor is connected with the harmonic reducer;

• the harmonic reducer is fixed on an internal structure of the shell by the bolts, and an output shaft of the harmonic reducer is connected with the rotary table connecting piece through the set screw;
• the rotary table is connected with the rotary table connecting piece through threads, and is fastened with the nut through the gasket;
• three protruded eccentric shafts are uniformly distributed at an outer edge of the rotary table and are connected with first ends of the connecting rods, and second ends of the connecting rods are connected with small protruded shafts of the contacts;
• the contacts are mounted in circular holes of the shell and are set to only axially move along the circular holes of the shell, so that the rotary table, the connecting rods, the contacts and the circular holes of the shell form a slider-crank mechanism, wherein an overall size of each of the contacts is smaller than a size of each of the circular holes of the shell;
• when the stepping motor drives the harmonic reducer to rotate, the connecting rods drive the contacts to do linear motion, and the contacts are set to utilize the linear motion to complete operations of tensioning and loosening an inner hole of a hub;
• and each force sensor of the force sensors is mounted in a corresponding contact of the contacts, measures a size of a tensioning force between the corresponding contact and the inner hole of the hub in real time and transmits the size of the tensioning force to a controller of the stepping motor in real time, and once the size of the tensioning force is beyond a range allowed by the hub, the controller controls rotation of the stepping motor to adjust the size of the tensioning force,
• wherein each of the contacts comes into contact with the inner hole of the hub when tensioning the inner hole of the hub, and each of the contacts is separated from the inner hole of the hub when loosening the inner hole of the hub.