Jig device for main axis of machine tool

The utility model relates to a clamping device for main shafts of a tool machine, which comprises a push rod, a clamping jaw with a lacing assembly, and a spacing ring, wherein the clamping jaw is inserted with an output end of a top pull rod in a main shaft, and is contained in the main shaft and is butted against the outer side of the push rod; the spacing ring is assembled between the push rod and the clamping jaw, and the spacing ring is sheathed with an elastic assembly which is butted in the main shaft and between corresponding ends of the clamping jaw; by using the push rod and the clamping jaw to mutually form conical stringency spacing, and then the clamping jaw can fixedly clamp a tool holder; when the push rod and the clamping jaw disengage from the spacing, the clamping jaw penetrates through the lacing assembly and the elastic assembly to generate synchronous actuation by the lever principle, and then the clamping jaw can be rapidly moved to form a flanning shape, which enables the tool holder to be loosen. The utility model enables the operations of clamping tools and loosing tools to have stable and safe essential benefits, and then the utility model value of the tool machine industry is improved.