CLASSIFICATION OF CONNECTIONS MACHINE PARTS BY WEAR CONDITIONS

Abstract

The main reasons for the failure of machine parts are both breakdowns and wear. Parts that have failed are very diverse and are classified according to various characteristics: functional purpose, materials, workpieces types, weight and size, geometric features and other wear conditions. Machine parts are subject to various wear types (mechanical, thermomechanical, fatigue, corrosion, erosion, etc.). Wearing effects cause the formation of defects, and the operating conditions determine the various dominant wear types, which are typical of certain parts: changes in the surfaces size and shape; the appearance of scratches, burrs on the conjugate surfaces; the appearance of cracks, wear, crumple and chipping of work surfaces; wear and destruction of the thread, etc. The creation of effective friction units is associated with the provision of rational conditions for wear of the connected friction parts surfaces, taking into account a large number of different factors. These factors determine the choice of the parts materials to be joined; design of friction units; ensuring the rational loading of the friction pairs elements; appropriate protection of friction surfaces from the environment and other undesirable effects; ensuring a rational thermal regime by optimizing heat dissipation; geometric optimization of friction pairs, etc. All this led to a huge variety of friction units’ designs, tribotechnical materials, means of their control, etc. Therefore, the topical issue is the systematization and generalization of theory and practice based on the classification of wear conditions of machine parts connections. In the known works systematization of production experience results and scientific researches on details wear is carried out on worn types out details and physical mechanisms of wear. This does not take into account the uneven parts wear and their surfaces due to uneven specific pressures distribution and relative sliding speeds, differences in lubrication conditions, different supply intensity to the friction zone of abrasives and aggressive substances, wear particles removal and other conditions in contact. A system for classifying friction joints is proposed, which includes 16 groups of connections that differ in the parts geometry, their contact conditions, relative motion and wear. The proposed classification of friction connections according to the wear conditions provides the possibility of a systematic approach to generalize the experience of creating effective friction units stimulates research and development of more rational friction units’ designs, expands the transfer of innovative designs and technologies. It is also possible to exchange experience in the creation and application of perspective parts designs, friction units, ways to strengthen and restore them, taking into account similar wear conditions between different branches of mechanical engineering.