Ultrasonic hardening of the gear wheels of helicopter transmission

Abstract

Purpose. Evaluation of the effect of ultrasonic hardening on endurance strength, the magnitude and nature of the distribution of residual stresses in the surface layer of samples of gear wheels from steel 16Х3НВФМБ-Ш of helicopter transmission is done.Methods of research. For comparative tests on fatigue, special samples were made with a fillet in a number of 34 pieces, samples material of gear wheels is steel 16Х3НВФМБ-Ш, the technological process of making fillet samples is similar to the technological process of processing the cavities of the teeth of helicopter transmission gear wheels were used.Some samples (17 pcs.) were tested in the initial state, the rest of samples were subjected to ultrasonic hardening with balls. The tests were carried out on a ВЭДС-400 vibrostand at room temperature and resonant vibrations in the first bending form of cantilevered samples.Received results. In the work, based on the results of experimental studies, the effect of ultrasonic hardening on fatigue resistance, the magnitude and nature of the distribution of residual compressive stresses in the surface layer of samples of steel 16Х3НВФМБ-Ш were schown.Scientific novelty. Experimental studies have shown that ultrasonic hardening increases the fatigue resistance of samples from steel 16Х3НВФМБ-Ш and forms in their surface layer the residual compressive stresses in the range from -533 to -23 MPa. The endurance limit of the original samples is σ-1 = 588 MPa. The endurance limit of samples with a fillet, which surface was subjected to ultrasonic hardening with steel balls, is σ-1 = 666 MPa.Practical value. Based on the results of this experiment, it is possible to develop a rational technological process for the manufacture of gear wheels from steel 16Х3НВФМБ-Ш of helicopter transmission, ensuring their high performance.