Machine head multi-telescopic-knife mechanism capable of assisting upper head changing mechanism in automatically breaking yarns and control method thereof

The invention relates to the technical field of glass fiber kiln wire drawing equipment, in particular to a machine head multi-telescopic-knife mechanism capable of assisting an upper head changing mechanism in automatic yarn breaking and a control method of the machine head multi-telescopic-knife mechanism. The yarn breaking device comprises a machine head main shaft, a spring seat, a cylinder body seat, a yarn breaking blade, a blade guide end cover and a blade driving device. Yarn can be reversely cut off at the yarn breaking blade by controlling the speed difference change of the machine head with the telescopic yarn breaking blade and the V-shaped yarn winding sheet of the auxiliary upper replacement head, an automatic yarn cutting device does not need to be additionally arranged, the broken yarn is neat and neat, no wool yarn is splashed, the multi-air-cylinder telescopic yarn breaking blade is shrunk after the full-drum machine head is stopped in transposition during drum unloading, and the yarn breaki