PSI - Issue 59

Andrii Senyk et al. / Procedia Structural Integrity 59 (2024) 502–507

503

2

Andrii Senyk et al. / Structural Integrity Procedia 00 (2024) 000 – 000

1. Introduction The annual demand of the national economic complex of Ukraine for drive roller and bushing chains (DRBC) is about 40 million linear meters. Hundreds of thousands of tons of high-quality rolled steel are used for their manufacture. The friction conditions of the roller and bushing joint surfaces and their wear resistance are significantly affected by such shape accuracy indicator as the deviation from roundness of the inner cylindrical surfaces (ICS) of the rolling bushings. Analysis of the existing literature (Dubinyak et al., 1988; Krivyi 1990; Krivyi 2017) related to the investigation of the shape accuracy of the rolling bushings showed that the deviations from ICS roundness of rolling bushings were evaluated without taking into account the significant impact of technological process of a particular manufacturer on the accuracy of ICS shape, as well as without elements of dispersion analysis, which significantly reduced the practical value of the known researches. Therefore, the harmonic-dispersion analysis of deviations from ICS roundness of the DRBC rolling bushings, based on statistical data, as the result of which the contact areas of ICS bushings with their highest accuracy indicators with the rollers will be determined is an important task which ensures a significant increase in the wear resistance. The investigation of the deviation from ICS roundness was carried out on bushings for chains with steps of 9.525 mm, 12.7 mm, 15.875 mm manufactured by Dauhavpils (Latvia), as well as on bushings with steps of 19.05 mm and 25.4 mm, respectively, produced by PROMTECHKONSTRUKTSIA (Ukraine) and Bishkek (Kyrhyzstan). In order to obtain the roundness evaluation characteristics in accordance with the requirements of existing standards, samples of N = 30 pieces were formed. Due to the presence of springing cards during bushing ICS folding, they have significant deviations from roundness and it is impossible to use the existing devices for their measurement. In this case, the ends of the rolling bushings are ground and then scanned. Using Auto CAD software, the obtained end prints are enlarged in accordance with the specified scale and the traces of bushings ICS are obtained in the form of distorted circles, i.e., circlegrams, each of these circular circles is inscribed adjacent to at least three points of the profile the farthest from each other, the circle is divided into і ( і=1, 2, 3…24, 48 ) uniformly distributed positions and in each of them the distances from the points of the real profile of bushings ICS to the adjacent circle are determine and finally the values of deviations from roundness j i EFK   are obtained. The position of the fold seam was taken as the starting point. Deviations from the roundness of the bushings ICS with certain size of DRBC were represented as an ensemble of implementations. The stability of the technological process of bushings manufacturing and the reliability of statistical estimates according to the hypotheses: the constancy of the instantaneous dispersion of the deviation from roundness - Δ and the absence of systematic errors were checked according to the λ 0 criterion (Kolker (1976)). With the same volumes of samples N = const, the value of the criterion λ 0 was determined by the following formula:

M M M m S S S S 2 2 2 2 ... 2 1 

0  

,

(1)

1

(

)

m



 m 2

  

  

m

m

2

S      1 1 i i M i

S

M   

where

- is size N sample dispersion;

i

i M  is the average value of the deviation from roundness of the small і -th sample;   m n n i M m i            1 is the average deviation from the roundness of the sample N. 2 1 M S is dispersion of the і -th small sample; m is the number of small samples; n is small sample size.