Camshaft hobbing tool positioned through centre

The utility model discloses a camshaft hobbing tool positioned through a centre. The camshaft hobbing tool comprises a first base, a second base, a rotary cylinder, a driving gear, a sealing ring, driven gears, screws, centre positioning seats, a lower centre, an angle positioning sleeve, an end face positioning plate, telescopic top pillars, friction discs, compression springs, steel balls, a positioning pin and fixed pins, wherein the two rotary airflow channels are arranged on the first base and the sealing ring and communicated with second air vents in the second base; the compression springs and the steel balls are mounted in the axial blind holes of the screws so as to form a differential device with the counter bores in the friction discs. According to the tool, pre-tightening of a workpiece is achieved through the automatic adjustment of the differential device, that clamping precision is influenced due to end face machining errors is prevented, the processing method that the workpiece rotates and a c