Multi-size compatible mechanism

The utility model provides a multi-size compatible mechanism. The multi-size compatible mechanism comprises a fixing plate, and a first driving assembly, a second driving assembly, a third driving assembly and a fourth driving assembly which are sequentially connected end to end to form a ring are installed on the fixing plate; the first driving assembly comprises at least two sets of limiting sliding rails, at least two sets of limiting sliding blocks, a set of limiting plates, a set of lead screw modules, a set of moving plates, at least two sets of connecting guide rails, at least two sets of connecting sliding blocks and connecting pieces. According to the multi-size compatible mechanism provided by the utility model, the positioning mechanism not only can be compatible with the positioning of products with the sizes of 8-28, but also can be placed in various machines for use, the application range is wide, the positioning is accurate, the size is adjusted, screws are not used for fastening and adjusting,