Analysis of the laws of distribution of elements resources in the investigation of reliability of the press-granulator

Abstract

In the conditions of mechanization and automation of agricultural production the importance of indicators of reliability and durability in the overall assessment of the quality of machinery increases. In the meantime, the task of ensuring the reliability of the machines becomes more difficult due to the continuous increase in the power intensity of the parts and components as a result of increased operating speeds, increased loading during the universalization of the machines and many other factors associated with the progress of agricultural machinery. The peculiarity of the functional purpose and operation of the means of mechanization in animal husbandry is to ensure the continuity of biotechnical communication: operator - machine - animal - environment. This is possible only under the condition of the constant maintenance of the specified facilities in working condition, under which the coefficient of readiness of each unit should be at the level of 0.95 ... 0.98. There are several dozen distributions in the theory of reliability that can be used to describe experimental failure data. Considering different models of failures, a number of distributions are distinguished: normal, logarithmic normal, Weibull, gamma and exponential, which are the basis for the construction of models of durability of non-restored livestock products, replaced in case of failure of spare parts. These distributions cover, respectively, gradual, wear-out, fatigue and sudden failures of mechanical systems, complex systems that have undergone a period of service, as well as systems that are operated under severe conditions under the influence of mechanical and climatic loads. Characteristic of a normal distribution is that the failure rate starts at 0 and increases with time. This means that the failure flow is not stationary and there is an aging element. In the region of small values of t the aging of the elements does not significantly affect the reliability, so the probability of trouble-free operation of the product decreases slightly. After prolonged operation of the system, the failure of which elements have a normal distribution, its reliability rapidly decreases, so the probability of trouble-free operation decreases. Normal distribution is used for the gradual change of parameters, or in cases where the proportion of sudden failures is very small, that is, for products operating in favorable operating conditions. It is specific to describing progressive failures. The Weibull distribution corresponds to the situation of the weakest link in a set (a system consisting of a group of elements), and is also a flexible enough function to equalize various failure statistics well, which can be a model of failure of mechanical objects. Exponential distribution occurs in cases where the products are complex and the number of failures of different elements of the products with different intensity is possible. It has maximum density at the moment of switching on, ie it corresponds to low technology and quality of manufacture and assembly, excludes technological elaboration and finishing.