The invention relates to a special boring clamp which is composed of a main positioning plate, a bottom plate, a reinforcing plate, a positioning origin
bushing, a rhombic positioning pin,
drill jig assemblies, a first pressing plate
assembly, a second pressing plate
assembly, a first jacking supporting
assembly, a second jacking supporting assembly, a third jacking supporting assembly and an inner rack pressing assembly. An origin
bushing hole, a rhombus pin hole and three
drill jig sleeve holes are machined in the main positioning plate, the special boring clamp is provided with three same
drill jig plate assemblies according to the characteristics of machined products, and each drill jig assembly is composed of a first drill sleeve, a second hinge sleeve, a third hinge sleeve and a fastening locking screw. The first pressing plate assembly is composed of a flat pressing plate, a first pressing plate locking bolt, a first spring pad, a first supporting bolt and a first locking nut, and the inner rack pressing assembly is composed of a T-shaped support, a hook-shaped top pressing plate, a rotating shaft pin, a cotter pin, a third locking bolt, a spherical elastic pad and a conicalelastic pad. By means of the scheme design of the special boring clamp, the
machining problems that when a specific outer arc-shaped cavity piece and an inner rack assembly are machined, positioningand clamping are difficult,
dislocation is likely to happen, and scrapping is likely to happen are solved.