Abstract: A rotary joint for delivering a mixed fluid from a radial inlet of a joint element axially through a high speed rotating shaft. Leakproof protection is first realized by one side of a wear block being compressed against an end face of the shaft. A spring presses a washer and an O-shaped ring against the other side of the wear block to prevent leakage and filter most solid impurities. Leakproof protection is also realized by covering the shaft with a seal to isolate leaking fluid from the first protection.

Abstract: A polishing tool includes a tool body and a polishing member which is mounted rotatably on the tool body and which has a central hole unit formed through the polishing member. The working surface of the polishing member has a plurality radially extending slots which are spaced apart from each other in an angularly equidistant relation and which extend from the inner periphery of the working surface to the outer periphery of the working surface. A plurality of flat working surface sections are defined on the working surface of the polishing member by the slots. When a slurry consisting of a lubricating liquid and abrasive grains flows onto the working surface of the polishing member via the central hole unit and when the polishing member is rotated on the tool body, each of the abrasive grains moves across all of the slots and from the inner periphery of the working surface to the outer periphery of the working surface, by hydrodynamic effect, so as to polish positively and effectively the workpiece.