Tula State University (Tula, Russia):

O. I. Boriskin, Dr. Eng., Prof., Head of the Chair of Instrumental and Metrological Systems, Director of Polytechnic Institute
N. G. Stakhanov, Cand. Eng., Prof.
I. V. Gorynina, Post-Graduate, E-mail: goriv1356@gmail.com

The increase in hardness of working surface of gear wheels is an effective way of improvement of load capacity and durability of gears. However the requirements for rigidity of gear-cutting equipment and for stability of cutting tools are significantly increase. Actually carbide-tipped worm cutters are widely employed to process small-pitch wheels of steel, cast iron, non-metallic materials as well as to cut tempered cylindrical wheels with big gear module. Suchlike cutters are made from several parts with removable multifaceted cutting plates due to deficiency of hard alloys. However, the problems of shaping such cutters have not been solved enough. In the design and manufacture there are deviations in the profile of the tooth-plate, which can then be transferred to the workpiece. In the article the main sources of arising errors are identified, techniques and methods are developed that allow them to be minimized. In particular, a theoretically exact calculation of worm cutters is proposed, which excludes deviations that depend on the profiling method. The analysis of geometrical accuracy of such cutters has shown that if the front corners are present, the profile of the lateral sides of the tooth will be asymmetric. This complicates the use of double-sided plates, since when they rotate around the longitudinal axis by 180° new cutting edges come into operation that do not coincide with the original ones. To avoid this phenomenon, the authors of the article proposed two variants of using such plates with the preservation of a theoretically correct profile. The first of these is to make a helical back surface of the involute worm mills. In this case, when the plate-tooth is rotated relative to the longitudinal axis, the profile angles will be required. The second option is to use two working enclosures with different thread directions. The recommendations proposed in the article will allow to increase the accuracy of worm gear cutters and economically use the scarce solid alloy.

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