PSI - Issue 59

Andrii Senyk et al. / Procedia Structural Integrity 59 (2024) 508–515

509

2

Andrii Senyk et al. / Structural Integrity Procedia 00 (2023) 000 – 000

1. Introduction One of the most important indicators of the quality of cross-sections of cylindrical surfaces, including the rolling kingpin bushings, is the deviation from roundness. According to the definition, the deviation from roundness is the maximum distance from the real point of the profile to the adjacent circle. The rolling kingpin bushings are widely used in the undercarriage of a number of vehicles, particularly, UAZ-469 and UAZ-452. Deviation from roundness - Δ, as one of the main indicators of shape accuracy, has significant impact on the operational properties of the contacting surfaces and is regulated by existing standards: DSTU 13568:2006 (ISO 606:1994) (Ukraine); BS 308, 1253 (UK); DIN 7182, B14 (Germany); U-14-5 (USA, Canada, Czech Republic, Switzerland). According to existing technologies, such bushings are made of blanks in the form of rectangular cards of certain sizes by periodic deformation and their further pressing into the holes of other casing parts, such as journals, gas distribution rocker housings with further finishing mandrelizing of their internal cylindrical surfaces (ICS), Fig. 1.

Fig. 1. Technological scheme for the manufacturing of rolling kingpin bushings: ( a) feeding the card until it stops; (b) forming of U-shaped blank; (c) forming of the rolling bushing; (d) pressing the rolling bushing into the journal hole; (e) calibration with ICS mandrel. 1 - matrix, 2 - bushing-card blank, 3 - stop, 4 - cylindrical mandrel, 5 - punch; 6 – rolling bushing, 7 - upper punch, 8 - catcher, 9 - journal body, 10 - support, 11 - mandrel. While using rolling kingpin bushings in the undercarriage of automobiles, in particular UAZ vehicles, which operate under significant dynamic loads during vehicle movement, the shape accuracy of bushing ICSs and the outer cylindrical surfaces of the kingpins is of great importance to ensure the permissible pressures in the hinges. A significant number of scientific papers have been devoted to the investigation of shape accuracy, in particular, deviations from roundness. A number of researchers (Kryvyi et al., 2016 ; Dzyura et al., 2014 ; Kryvyi et al., 2007; Kryvyi et al., 2010) present deviations from roundness in the interval [0- 2π] as stationary or nonstationary periodic random functions with 2π period. Deviations from roundness, cross-sections of solid cylindrical surfaces formed by turning or grinding, drawing in fillers are represented as stationary random functions. Correlation functions and their characteristics are used to estimate these deviations. Deviations from the roundness of cross-sections of hollow cylinders, for example, rolling bushings, which are formed by periodic or sequential deformation followed by calibration in fillers, and at the same time the bushing butt joint is the beginning and the end of interval [0- 2π], are represented as non-stationary random periodic functions. Analysis of existing methods for evaluation of deviations from roundness (Dzyura et al., 2014) of cross-sections of cylindrical surfaces formed by existing technologies has shown that they use the mathematical apparatus of trigonometric Fourier series and consider these deviations in the probabilistic aspect. In cases where the deviations from roundness exceed the tolerance fields for certain dimensions by several orders and technical capabilities of existing devices for these deviations control do not allow them to be determined, there is a need to create a new methodology for their determination and a new technology for their manufacturing. Therefore, the creation of new technology for the manufacturing of rolling bushings, taking into account the significant macro-geometric deviations formed after the first technological operation - rolling the card into the