TECHNOLOGICAL WAYS TO ENSURE THE QUALITY OF REPAIR OF RESOURCE ASSEMBLY UNITS OF ENGINES

The resource of repaired engines depends on the resource of basic assembly units and parts. The resource assembly units of the engine are the cylinder block assembly and the crankshaft assembly. (Research purpose) The research purpose is determining the hardness and microstructure of the material of the crankshaft necks of the SMD-62 engines, as well as micrometering of the geometric parameters of the working surfaces of the crankcase block of the SMD-62 engines on the assembly line. (Materials and methods) The hardness of the crankshaft necks was measured on a Rockwell device; the geometric parameters of the crankcase were measured by universal measuring instruments. (Results and discussion) The crankshaft necks were quenched asymmetrically by high-frequency currents. The high-strength area in depth ranges from 1.5-4.0 millimeters. Hardness in the zone of deeper calcination, corresponding to TC (62-46 on the Rockwell scale), is located at a depth of up to 2.3 millimeters from the surface. Then the hardness decreases and at a depth of 3-4 millimeters from the surface is 25-28 units. The upper and lower seat belts for the cylinder liner, the inner diameter of the cylinder liners, and the sockets for the liners of the crankshaft main bearings were monitored before and after pressing the liners into the crankcase. To improve the accuracy of the shape of the working surfaces of the crankcase after boring the beds, it is necessary to increase the rigidity of the blocks by installing cylinder liners and then tightening the covers of the beds before boring. (Conclusions) All crankshafts, after grinding to the next repair size, were subjected to a neck hardness measurement. Shafts whose neck hardness is below 46 units on the Rockwell scale should not be installed in engines due to a decrease in their durability. It is necessary to install a stand for pressing the sleeves before boring the beds on the repair line of the crankcase of the SMD engines, which will prevent uneven deformation of the crankcase from tightening the support covers and reduce the distortion of the shape of the seat belts of the block and cylinder liners after installation by one and a half to two times.