Trimming device

The invention relates to a trimming device which comprises a lower shaft rotationally arranged on a base plate of a sewing machine. A cam is arranged on the lower shaft. The trimming device further comprises a drive shaft, an outer crank, an inner crank, a tangent line rotating assembly, a cutter assembly and a drive assembly. A guiding strip parallel to the drive shaft is arranged on the outer crank, one end of the guiding strip is provided with a crank arm extending towards the lower shaft, a roller is arranged on the crank arm, a clamping groove is formed in the inner crank, the front sideand the back side of the inner crank are provided with a sliding block and a reset unit respectively, the inner crank drives the cutter assembly to swing around the drive shaft through the tangent line rotating assembly, the drive assembly can drive the outer crank to reciprocate along the drive shaft, according to the trimming device, by adopting the structure of the inner crank and the outer crank, the axial positions o