Assembling and centering structure for processing tool

A positioning assembling structure of a center of a processing tool comprising:

• a clamping handle comprising a receiving cavity;
• the receiving cavity formed at an end surface of the clamping handle and comprising:
• a recess adjacent to an opening of the receiving cavity;
• the recess including:
• a plurality of curved surfaces, radiuses of curvatures of the curved surfaces being the same but centers of the curvatures of the curved surfaces being different;
• and
• a central positioning hole, wherein a wall of the central positioning hole is a cylindrical surface;
• the central positioning hole being farther from the opening of the receiving cavity than the recess;
• a width of the recess gradually decreased toward the central positioning hole thereby forming the recess in a conical shape;
• a processing head comprising:
• a cutting portion configured to machine a workpiece;
• and
• an assembling portion configured to be received in the receiving cavity of the clamping handle, securely mounted on the cutting portion, and comprising:
• a protrusion matching and received in the recess;
• the protrusion including:
• a plurality of curved surfaces, a number of the curved surfaces of the protrusion being equal to that of the curved surfaces of the recess;
• radiuses of curvatures of the curved surfaces of the processing head being the same but centers of the curvatures of the curved surfaces of the processing head being different;
• and
• a central positioning column configured to match and be received in the central positioning hole, a wall of the central positioning column being a cylindrical surface;
• the central positioning column being farther from the cutting portion than the protrusion;
• a width of the protrusion gradually decreased toward the central positioning column thereby forming the protrusion in a conical shape;
• and
• a fixing part connected with the clamping handle and the processing head;
• wherein when the assembling portion is received in the receiving cavity, each one of the curved surfaces of the protrusion abuts a respective one of the curved surfaces of the recess, the wall of the central positioning column abutting the wall of the central positioning hole and a rotating axis of the clamping handle and a rotating axis of the processing head are arranged in a line.