The calculation of the transmitted torque upgraded fixed connection

Abstract

Abstract. Renouncement and downtime of combine harvesters in operation lead to significant financial losses. One of the most important reasons for the downtime of this machinery is the failure of key connections, which account for up to 10.5 % of the total number of failures. The main disadvantage of this connection is that the keyway is a stress concentrator that reduces the fatigue strength of the parts, leading to an asymmetric deformation of the shaft and hub. The wear of individual parts of the fixed key connection is mainly due to the gradual surface destruction of the material of the parts, which is accompanied by the separation of particles, by changing the dimensions, geometric shape and properties of the surface layers of the material. The presence of gaps in the "bushing-shaft" connection also affects the reliability of the belt drives, since their constant pulsating loads, unloading and changing the inter-axis distance with variable frequency due to the turns of the key with the hub, take place. For real operating conditions of combine harvesters, the most effective installation is instead of existing key connections, where technical requirements permit, a removable hub for mounting a rotating element on the drive shaft, which can be made in the form of a repair kit with sufficient accuracy in the repair shops of farms. The use of the proposed modernized design of movable key connections first of all eliminates the main cause of the failure -the relative radial movement of the contacting mating parts, and also allows the hub and shaft to be pulled together without creating an eccentricity, which in turn will increase the service life of the connections. The article presents a method for calculating the transmission torque upgraded fixed connection, proposed for use in drives of combine harvesters instead of standard key connection. It presents the forces and tightening the conditions of the proposed strength of the connection.Keywords: combine harvester, resource, conical sleeve, torque, fixed connection. IntroductionIt is based on previous studies [1] that the refusal key connection harvester is a loss of efficiency of the whole machine. Therefore, in order not to disrupt the process of harvesting of grain crops, necessary measures have to be taken to reduce the cost recovery time performance of critical parts and components of the combine and increase their resources, including the key connection.Professor A.I. Yakushev [2; 3] proposed to use the factor of accuracy, which is the ratio of functional and design tolerances, to determine the accuracy of the geometrical parameters of the connection. Moreover, the accuracy stock should be created for each functional parameter affecting the performance of the product. According to the scientist, choosing the landing with the greatest accuracy factor of safety the durability of mobile connections increases, as the stock of materials for wear and the operational tolerance of landing increases.I.V. Kragelsky developed a frictional fatigue wear model that de...