Technology of electrospark hardening of cutting surface of feed mixer knives

Abstract

The research is aimed at ensuring the durability of the knives of a feed mixer-distributor with a vertical cutting-chopping and mixing scheme of feed preparation. The analysis of the wear process of the feed mixer knife found that the loss of performance occurs due to the violation of the geometry of the working edge of the knife in the course of mainly abrasive wear. The required level of durability can be achieved by reducing the wear rate. Strengthening the front surface of the knife cutting teeth increases the resource of the working body. Strengthening by electrospark alloying is considered as one of the technological methods. At the same time, an increase in the hardness of the working surface of the edge is achieved, while providing both fatigue and impact strength. When developing the technology, a comparison was made of various materials for forming a coating. The optimal rods are made of steel R5M6 (HSS) and a surfacing electrode T-590. The development of the operating parameters of coating deposition on the BIG-4 installation showed that the oscillation frequency of the electrode and the pulse energy have the greatest influence on the quality of the resulting coating. A microstructural analysis of the coating obtained during alloying in terms of microhardness and porosity has been carried out. For practical use, a technology has been developed and applied for hardening the knives of the feed mixer made of grade 45 carbon steel, which have acquired wear resistance at the level of knives made of 65G manganese steel spring. The results of life tests of hardened working bodies in the production conditions of a company engaged in dairy cattle breeding are presented, which showed an increase in the resource of the feed mixer knives by 67%. Conclusions are made about the expediency of using the developed technology to obtain a hardening coating on the cutting edge of the feed mixer knife.