Dynamic distributing expanding device of tyre builder

The invention relates to a power expander for a tire building machine, wherein the front, the rear and the middle of a main shaft are sleeved with slide seats and fixed seats; a linear driver on the rear of the main shaft is connected with a slide seat which is arranged on the rear of the main shaft; 2 to 4 push rods are connected with various slide seats, so as to maintain synchronization of the push rods and the slide seats; a motor on the rear of the main shaft is connected with a power roller through a driving mechanism and a universal joint by means of driving; both ends of the power roller are hinged with the slide seats and the fixed seats on the front and the rear of the main shaft through linkage mechanisms, and are angulated at a degree of between 5 and 10 DEG with the main shaft; two ends and middles of 3 to 20 sets of driven rollers are hinged with corresponding slide seats and corresponding fixed seats through linkage mechanisms; the driven rollers and the power roller enclose the main shaft and