Design and performance test of variable diameter threshing drum of combine harvester

During the rice harvesting process of combine harvester, it is necessary to adjust the working parameters of the threshing device in time according to working conditions to ensure operational efficiency and performance. This paper designs a variable diameter threshing drum, develops a device for diameter regulation with self‐locking function, and its installation process and working principle are introduced in detail. A force analysis and modal analysis were carried out on the device for diameter adjustment of variable diameter threshing drum. It aims to ensure that the design dimensions of the constant speed spiral disc and claws in the device for diameter adjustment are in compliance with the self‐locking conditions, and effectively ensure the reliability of the device for diameter adjustment. A field experiment was carried out to check the reliability of the developed system. A regression analysis model takes the feeding rate, threshing gap and drum speed as influencing factors. The grain separation loss rate and damage rate as performance indexes were established, and calculations for multiple target optimization were performed. The experimental results showed that the threshing gap could be adjusted in real time according to the different feeding rates of the variable diameter threshing drum.