Investigation of the Causes of Premature Failure of the Crown of the Ripper Structure Produced Using Direct Re-Engineering Technologies

Abstract

Abstract.. When testing imported ripper bits for bulldozer equipment, their premature failure was observed. In the process of studying the loading of the crown by the contact pressure of rocky soils at P = 11.5 MPa, it turned out that only a tight, gap-free installation of the crown on the seating part of the ripper strut ensures reliable operation and protection of the strut from wear and promotes its long-term operation in conditions of rock crushing. It has been established that the strength condition for the crown is satisfied only in the case when the landing part of the crown itself maximally touches the landing part of the ripper post, that is, the contact of the crown with the post is carried out along the maximum area of contact - contact. In this case, equivalent stresses are observed that are less than the yield stresses for steel, which was proposed in the study as wear-resistant for working on rocky soils. The study carried out numerical calculations of stresses and displacements in the crowns for various methods of their attachment to the landing part of the ripper strut. In the first case under consideration, the strength conditions are observed when the crown is working on rocky soils; in the second case under consideration, the strength conditions are not met and characteristic places are shown in which the safety factor is less than 1.3 (30%). Based on the results of the study for this case (numerical modeling), it was decided to increase the cross-section of the transition point of the cantilever part of the crown to its landing part by 10%. At the same time, it was determined by calculation that with an increase in the cross-sectional area of the transition point of the cantilever part of the crown to its landing part by 10%, operational reliability will increase by 20-30% when the ripper operates on rocky soils. As a result of the study, the possibility of using steel grade for crown-type products was experimentally confirmed.