Design and Experiment of Variable-speed Straw Chopping Machine Based on PLC Control with Equal Diameter Cam Transmission

To enhance the chopping quality of the maize straw chopping machine and address issues such as the inability to adjust traditional straw chopping parameters, a straw variable-speed chopping device based on a programmable logic controller (PLC) controlled mechanism utilizing an equal diameter cam mechanism for reciprocating motion was designed. Through analyzing force variations during straw chopping underground support conditions, the primary factors influencing the effectiveness of straw chopping were identified, and the LS-Dyna software was employed to determine the range of values for these factors. Through theoretical calculations and dynamic simulation analysis, the motion trajectory of the chopping blades was optimized, and key component parameters of the chopping mechanism were determined. To improve the chopping pass rate of maize straw chopping process, a pump-valve-motor speed regulation model was established. A human-machine interface was designed for operational parameter settings, facilitating rapid matching of chopping device operational parameters under different straw cover conditions. Experimental trials were conducted, with forward speed and straw cover as test factors and straw chopping pass rate as the evaluation index. The results demonstrated that there was a significant increase in chopping pass rate with the increase of chopping speed when the field straw cover was constant. Conversely, with a constant chopping speed, the chopping pass rate was decreased as field straw cover was increased. Beyond chopping speed of 200r/min, the chopping pass rate reached over 90% and remained relatively constant. To further validate the experimental results, a comparative test was conducted between variable-speed and constant-speed straw chopping methods, revealing straw chopping pass rate of 92.17% for the variable-speed method compared with the constant-speed method. This device achieved precise control of operational parameters for straw chopping, providing technical support for the intelligent development of straw chopping machines. © 2024 Chinese Society of Agricultural Machinery. All rights reserved.