Geometry and machining of concave profiles of the ZK-type worm thread

This paper is concerned with the possibility of concave thread making by tool of straight line. Geometry of worm thread formed by tapered end mill is presented. Machining of concave worm threads is described. It was found that high compatibility of the shape of the machined profile with theoretical one took place. Surface roughness of worms formed by rotary file is comparable with that of commercial worms. Developed method of machining allows easy concave profiles of worm thread forming using universal commercial tools.