Specially created regular Surface reliefs of the latter play an important role in improving the reliability and operational properties of machine parts. In this case, serial equipment is used to implement: machine tools, presses, drawing mills, etc. Unlike other modification methods, this process can be form-forming, that is, the workpiece gets new desired dimensions, which are combined with regular reliefs of the surface layer of the part.
Based on the above, the aim of the study was formulated – to improve the operational properties of vehicle parts by applying regular micro - and macro-reliefs for technological and operational purposes by deepening linear indenters.
The theoretical foundations of the study allowed us to put forward the position that when indenting materials by deepening a linear indenter, the factors of strong influence on the depth of the relief groove are the normal force applied to the tool and the physical and mechanical properties of the studied materials.
For the first time, a classification of regular reliefs was created according to the methods of obtaining cold plastic deformation and cutting processing and for their intended purpose: for preliminary separation of the allowance during cutting processing; for preparing the surfaces of parts for applying coatings, including film antifriction; for creating mazes on the surface of parts for lubricants; for preliminary separation of fragmentation shells of ammunition; for creating reinforced new load-bearing surfaces, in particular discrete ones when restoring worn parts; for obtaining complex profiles on the surfaces of holes of parts: keyway, spline, internal teeth of gear engagement; aesthetic purpose.
The calculation of the effect of the depth force and geometric parameters of a linear indenter on the shape and dimensions of the relief groove is developed: a depth of 0,02-5 mm; base radius in the range of 0,005-0,5 mm and cross-sectional angles 60°; 70°; 80°; 90°; in this case, the depth force will be affected by friction, reducing this force by 23% for the indenter angle of 60° and by 14% for the 90° angle.
Press hydrofected equipment for experiments with a force of 0,02 MN and 0,2 MN was selected; linear indenters made of hardened steel P18 with an angle at the top of 60°-90° were created; the grades of the studied materials were determined: 2 grades of alloy steels (steel 38ХН3МА and steel 12Х18Н10Т), gray cast iron ( iron gray ferritic–perlite СЧ20 and cast iron gray ferritic malleable КЧ 33-8), copper-based alloys ( bronze foundry tin Бр ОЦС 5-5-5 and brass deformable L62), duralumin D16 (2117) and titanium alloy VT6.
The theoretical provisions on the effect of the deepening force, hardness and plasticity on the depth of the relief groove are confirmed experimentally. In this case, these factors are manifested both as a direct effect on the optimization parameter, and through intermediate factors: the rounding radius and angle at the top of the indenter, as well as the composition of ICF and the depth rate. The first two interval factors strongly affect the depth of the groove, and the last two have a weak effect. The relationship of phenomena in relief formation by indentation is constructed and an experimental dependence of the groove depth on the process factors is obtained.
A method for restoring worn parts by deepening a linear indenter has been developed. It is established that the height of the part size increment is equal to half the depth. The angles of the indenter profile for deepening should be about 60° from the position of strength and stability of the tool, and the radius at its top should be within 01,– 02, mm.
Based on the mechanics of deepening a trapezoidal indenter into a rigid plastic half–space, a method for obtaining spur gears of involute internal engagement with the module m=0,25-2,5 mm has been developed. The process is carried out on a rigid multi-tooth mandrel by copying according to the reduction scheme. The problem of calculating the stress state is considered, as a result of which the deepening force of a trapezoidal indenter is determined as the sum of the deepening forces of a sharp wedge and its flat section. A typical technological process of the method for obtaining internal gearing wheels is presented , including the preparation of the hole of the tubular billet , the CPD method itself, and the finishing operation of thermal and abrasive processing and, if necessary, anhydrous nitriding.
