Retractable friction stir welding spindle

A retractable friction stir welding spindle comprising:

• an electric spindle system and a retracting mechanism;
• wherein, in the electric spindle system, a first angular contact ball bearing (7) is installed inside a front bearing chamber (5), a rear end of the first angular contact ball bearing (7) is locked by a first threaded retaining ring (8), a left side face of a connecting sleeve (16) is fixed with an outer edge of an electric spindle shell (9) by bolts, and an end cover (18) is fixed with an end face of the connecting sleeve (16) by bolts;
• a hilt (2) is assembled on an end face of a hollow spindle (4) by bolts, and a stirring shaft shoulder (1) is installed and fixed with an inner hole of the hilt (2), forming an electric spindle without retracting function;
• a motor rotor (10) rotates after energization and drives the hollow spindle (4) to rotate, so that the hilt (2) and the stirring shaft shoulder (1) rotate together;
• in a retracting machine, a stirring needle (19) and a retracting structure (20) are connected by threads and then stretch out from the stirring shaft shoulder (1), a rear part of the retracting structure (20) of the retracting machine is connected to a tail end cover (18) by bolt;
• when the electric spindle is energized, the motor rotor (10) therein rotates, driving the hollow spindle (4) to rotate at a high speed to complete spindle moving function;
• up and down translation motion of the retracting mechanism is completed by the retracting structure (20), so that the stirring needle (19) completes the function of gradual retraction, and then realizes function of eliminating keyhole in the friction stir welding;
• in the electric spindle system, a motor stator (11) is installed at one end of the electric spindle shell (9), and a side surface of the motor stator (11) is fixed to an inner wall of the electric spindle shell (9);
• the motor rotor (10) is installed on a fourth stepped shaft of the hollow spindle (4) with an interference fit, and its position is matched with the motor stator (11), the first angular contact ball bearing (7) is fitted with the hollow spindle (4).