РЕМОНТ КОРЕННЫХ И ШАТУННЫХ ШЕЕК КОЛЕНЧАТЫХ ВАЛОВ ДИЗЕЛЬНЫХ ДВИГАТЕЛЕЙ ПРИ ПОМОЩИ ДИСКРЕТНОГО УПРОЧНЕНИЯ

Abstract

Studies to assess the effect of discrete hardening of the crankshaft journals on its fatigue strength have been carried out. For this purpose, fatigue tests were carried out on two control parts of the D80 type crankshaft. It was established that the destruction of control part No. 1 occurred after 322,000 cycles, control part No. 2 after 201,000 cycles. The destruction zone of both control parts passes along the R8 mm transition fillet of the connecting rod journals. This allows us to conclude that the discrete hardening factor is not associated with fatigue failure of the control parts. In order to determine the service life of the crankshaft of the KamAZ 740 engine, strengthened in a discrete way (shaft of the fourth repair size), it was installed on a KamAZ 5320 vehicle. As a result of the tests, it was found that during the entire testing cycle the vehicle's mileage was 109,000 km. Moreover, at the time of completion of the tests, all parameters of the car’s engine met the technical requirements. The KamAZ 5320 vehicle is in operation to this day. Its mileage was 269,000 km without stopping for major repairs. To conduct operational tests of a cast iron crankshaft with discrete hardening of a D80 type engine, a 1D80B diesel generator engine was taken, which after assembly was subjected to full-scale testing. These tests included a 100-hour engine run-in, determination of the vibration level and amplitudes of torsional vibrations of the diesel generator shaft line in the operating speed range. The analysis of the vibration state of the engine showed that in all test modes the vibration level at the points under study does not exceed the norms (0.350 mm on the turbocharger housing and 0.150 mm on the generator foot). The maximum stresses from torsional vibrations were: 8, about 17.5 MPa; 4, 5 order 10.5 MPa; 1.5 order 10.0 MPa. The resulting stress levels are significantly lower than permissible. Tests of the 1D80B diesel generator showed its full compliance with the technical requirements for the operation of this engine.