In the result of the rolling bearing research it has been found that the bearing radial clearance, especially with a small number z of rolling elements z<15 besides technological factors depends on the rolling element location in the bearing during measurement. During operation the simple rolling bearing design is characterized by complex dynamic processes. In theoretical mechanics general technical calculations are carried out for absolutely rigid bodies that are not deformed during the working load application. This position is completely used in design diagrams as the deformations of races and rolling elements are not taken into consideration. If the bearing is manufactured and operated with a nominally reasonable value of the radial clearance, then the probability of its successful operation will be very high. During the bearing manufacturing it’s necessary to take into consideration the radial clearance as a geometric parameter along with other dimensions of the bearing. Analytical expressions for the radial clearance calculation have been obtained for the first time for odd and even layouts of the rolling element location in the bearing operating area. The calculation results for definite bearings are given. The justification of initial clearances and creation of the analytical method for the radial clearance determination represent a crucial task of the rolling bearing theory.
Rolling bearings have found wide application in mechanical engineering due to their design simplicity and high efficiency during the operation of machinery and equipment [1, 2]. At present the rolling element theory allows to fulfill complex static and dynamic calculations. The problems for the rolling bearing durability calculation, reduction of vibration and noise during the operation of machines and units are of particular relevance. The rolling bearing design simplicity is caused by a small number of component parts. However, dynamic and static processes appearing during the bearing operation possess a complex physical basis and are in need of further study and development. At present the dependence of the radial forces distribution on rolling elements along the bearing rotation angle exists only for the odd diagram of the working rolling element location using the Striebeck method. In the study a new additional design diagram is applied for the even symmetrical location of the bearing working rolling elements in the operating area, which allow to significantly improve the accuracy of performed calculations. The total number of rolling elements in a bearing can be an even or odd number, at the same time the number of working rolling elements taking up a workload in the Striebeck problem is always represented by an odd number. For this reason the known design diagram is of an insufficient accuracy, especially for a small number of rolling elements z. A new procedure of the problem solution relative to the determination of radial loads on rolling elements, where restrictions on the number of rolling elements are eliminated being accepted at present during the bearing calculation.
Horizontal oscillating vibrations of a vibratory road roller are of secondary importance in comparison with vertical vibrations that compact soil and asphalt concrete. The consideration of horizontal vibrations is required for the improvement of the vibratory roller design aimed at reducing the overall accompanying vibration on the vibratory roller and on a human operator, as well as for the calculation of vibration exciter rolling bearings and rubber-metal shock absorbers. Two research tasks of vibratory drum horizontal vibrations on a solid non-deformable base have been solved in the article. The assumption has been made in the first task that there is sliding friction between the cylindrical roller and bearing surface; in the second research task of horizontal vibrations the cylindrical drum rolls over a solid bearing surface without slipping. The mode of horizontal oscillating vibrations differs in phase from the mode of vertical oscillating vibrations by the angle φ = 0.5π. When creating vibratory rollers, manufacturing companies strive for increasing the operation efficiency of vibratory rollers at the expense of increasing the centrifugal exciting force while maintaining or reducing the total weight of the vibratory roller. As a result of which the oscillation mode appeared where negative effects of additional loading of rubber-metal shock absorbers were found, connecting the vibratory drum with the roller front frame and increasing the overall vibration of the vibratory roller. Dependences of horizontal travels, speed and acceleration of a vibratory drum have been determined during the road roller forward movement. During one turn of the vibration exciter rotation the forward movement of the drum becomes a non-uniform one, i.e. it takes an oscillating vibrating nature. Rules and recommendations have been developed for the study of sliding conditions, vibratory drum balancing over the bearing surface etc.
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