Development of Guide Rail Hitch Device Connecting Combine Harvester and Rapeseed Direct Seeding Machine

Abstract

Aiming at the issues of large inventory but low utilization of combined harvesters in the mid-lower reaches of the Yangtze River, as well as the problems of the longitudinal dimension of the conventional three-point hitch of tractors being large and the structure being complex, resulting in a large turning radius and unstable center of gravity for the unit, a guide rail hitch device suitable for connecting a combined harvester with a rapeseed direct seeding machine was developed by using a modular design approach. Based on the kinematics analysis of the conventional three-point hitch, the overall structure and working principle of the guide rail hitch device were determined from the aspects of compact structure and stable center of gravity. According to the matching relationship between the guide rail hitch device and the combine harvester and rapeseed direct seeding machine, theoretical analysis was carried out from the matching of width, center of gravity and tillage depth, and the operating parameters and structural parameters of the hitch device were determined. The ANSYS Workbench simulation software was used to carry out the modal analysis of the hitch device in a free state. By analyzing the characteristics of the external excitation frequency of the frame and the simulation results, an improvement plan for the structure of the hitch device was proposed. And the first six frequencies of the optimized device were 54.09Hz, 66.35Hz, 83.16Hz, 130.01Hz,143.52Hz and 174.88Hz, which were not within the range of the external excitation frequency. The static analysis of the optimized hitch device showed that the stress values of the suspension device at the highest lifting point and operating state were 50.531MPa and 140.56MPa, respectively, which were less than the allowable stress of 156.67MPa. The field test results showed that the whole machine ran stably. When the field test was carried out with the forward speed of 3.6 km/h, the stability of the ploughing depth was 87.42%, the soil breaking rate was 84.41%, the straw burying rate was 76.32%, and the flatness of the cage was 22.93mm. The test results showed that all the test indexes met the quality requirements of rape sowing.The research result can provide an idea for the research of a multi-purpose device.

Keywords: combine harvester, rapeseed direct seeding machine, hitch device, modal analysis