OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 6 No. 2 2024 a b Fig. 6. Microstructure of unetched microsection of the bearing outer ring areas with porosity, %: a – 8–9; b – 1–2 of solid lubricant concentrated in the pores of the metal matrix, respectively, to reduce the coefficient of friction between the spherical bushing and the outer ring of the bearing, and on the other hand, relatively large residual porosity reduces the ultimate strength of the ring material and the limit values of axial loads. In the case of using punches with a flat end surface (Fig. 7, a), the maximum relative density (0.98–0.99) was obtained in the zones of contact of punches with the end surface of the workpiece, where the intensity of plastic deformation of the material is significantly greater than in the central zone. Such areas of the blank after die forging are highlighted in (Fig. 7, a) in red color. However, the work of active forces and strain resistance in this case is somewhat greater than when using punches with internal chamfers (Fig. 7, b). The QForm program allows modeling a rectangular grid (Fig. 2, a), which is initially two-dimensional, but with some assumptions it is possible to calculate parameters for a three-dimensional grid with a certain error, provided that the radius R is constant at any point of the section. The displacements of nodal points were determined by the total displacement of each grid element, so we calculated linear and shear deformations based on the changes in linear dimensions and shape of a particular grid element (Fig. 2, b). Taking into account the results of simulation and using the thin section methodology, we selected representative elements by height and radius of the blank (Fig. 8, d) with coordinates Kh = hi/ho and Kr = ri/ro. As an example, the values of εxx, εyy and εxy calculated by known formulas [20, 21] are shown in (Fig. 8). The nature of the dependencies of εxx, εyy and εxy on the radius of the outer ring of the hinge, determined by the deformation of the coordinate grid and modeling by the QForm program, practically does not differ (Fig. 8). However, the values of component εxx, εyy and εxy calculated from the increment of the coordinate points of the grid are slightly larger than those determined by simulation. Assuming that the strain energy from the inner spherical bearing is insignificant, the strain energy balance equation is written in the following form: à d f A A A = + , (1) where Аa is the work of active forces; Аd is the strain energy; Аf is the work of external friction forces. Work of (external) active deformation forces: , = ∆ a d A P h (2) where Рd is the strain resistance force of the blank; Δh is the change in height of the blank.
RkJQdWJsaXNoZXIy MTk0ODM1