In mechanical transmission, rotary motion becomes reciprocating linear motion or reciprocating linear motion becomes rotary motion, which is generally completed by using eccentric parts [1]. For example, the lubrication pump driven by eccentric workpiece in lathe headstock, the crankshaft in automobile engine, etc. In order to adjust the center distance between shafts conveniently, eccentric shafts are usually used in the V-belt drive of planar linkage mechanisms. The general shaft can only drive the workpiece to rotate, but the eccentric shaft can not only transmit the rotation, but also the revolution

Eccentric workpiece is the workpiece whose outer circle and outer circle of the part or the outer circle and the axis of the inner hole are parallel but not coincident and offset by one distance. The distance between these two parallel axes is called eccentricity. The eccentric part between the outer circle and the outer circle is called eccentric shaft or eccentric disc; The part with eccentric outer circle and inner hole is called eccentric sleeve