Resumen
The subject of the research in the article are questions connected with the refined solutions of the isothermal stationary problem for the lubricating cooling liquid in the Newtonian state, taking into account the forces acting in the meshing of the cylindrical gears and the frictional forces arising on the active surfaces of the teeth in the area of contacting the involute surfaces and the thickness of the oil layer with taking into account the hydrodynamic characteristics of the lubricating fluid. The goal is to build a model of contact-hydrodynamic calculation of gear transmission. Objectives: to consider setting the thickness of the lubricating layer at a given external load, the speed of motion to determine the presence or absence of fluid friction, with the acquisition of initial data to determine the operability and durability of the coupled heavy loaded and critical gears of heavy lathes. The following results are obtained. The article presents a model developed by the authors for obtaining the correspondence of approximate and refined solutions in establishing the connection between the maximum contact-hydrodynamic pressure and the maximum Gertsev pressure. The analysis showed that for any operating parameters the maximum contact-hydrodynamic pressure should be less than or equal to the maximum Gertsev pressure. In the hydrodynamic (liquid) or boundary (semi-liquid) modes of friction, the oil layer not only significantly affects the wear state of the teeth, power loss and contact temperature, but also acts as an elastic medium damping the impact and changing the load distribution along the length of the contact lines. Thus, for closed involute transmissions with surface-hardened chemical-thermal treatment of teeth, the most urgent is to prevent deep (sublayer) damage caused by the concentration of the load in the gearing. Conclusions. The main physico-mechanical and chemical characteristics of the oil film under conditions of loaded contact of the engagement elements, namely the thickness of the oil layer and the coefficient of friction are the most important complex criterial parameters determining the beginning and the course of the process of contacting high-speed heavy-duty gears of the main drives of heavy lathes with CNC.