Авіаційно-космічна техніка та технологія (Nov 2018)
INCREASING DURABILITY AND ROBUSTNESS OF PLANE WHEEL HUBS BY STRENGTHENING TREATMENT
Abstract
Technology, equipment, and results of stand tests of plane wheel hubs and flanges strengthened by surface plastic deformation are described. The new method suggested by the authors is called vibrational-centrifugal strengthening treatment. It belongs to the method group of dynamic strengthening of revolutional shape parts. It is based on impact interaction of the part processed with a massive tool which is rolled over the strengthened surface of the part when under vibration. Moreover, the impact contact between the part and the tool occurs through a small number of deformable bodies. This provides formation of compressive residual stress in the contact places in the part material. For magnesium wheel hubs (alloy ML-12) residual compressive stress is within 110 MPa, for aluminium ones (alloy AK6) it is within 250 MPa. The degree of strengthening of outer zone material for magnesium wheel hubs is 45...59 % with surface micro-hardness increasing up to 1150 N/m2 and the thickness of the strengthened layer being 0.9...1.0 mm. When strengthening aluminium wheel hubs and flanges, the thickness of the strengthened layer is to be 0.6...0.9 mm with a degree of cold work being 25...30 %. Fatigue studies of a party of KT-141 type wheel hubs strengthened by the method (magnesium alloy MT-12) demonstrated their service life increasing up to 1000 take-offs and landings at the safety coefficient of n = 3.5. The lifetime of this type of wheel hubs strengthened by roller burnishing did not exceed 750 take-offs and landings; for unstrengthened ones, it made 500 take-offs and landings at lower values of the safety coefficient. Strengthening the wheel hub web KT-150K (aluminium alloy AK6) increases their lifetime by 28...30 % on average. Apart from plane wheel hubs and flanges, the method of vibrational-centrifugal strengthening treatment can be applied for increasing the lifespan of various parts of chassis components of circular section, for strengthening nonferrous metal webs of car wheels, radius blends and steel shaft journals etc.
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