Design and experiments of the clamping and conveying device for the vertical roller type corn harvesting header

Corn whole plastic film mulching on double ridges has been the main production mode of maize planting in arid regions of Northwest China in recent years. An effective technical way can be widely used to stabilize the corn yield. Among them, the vertical roller-type corn harvest header can greatly contribute to the simultaneous harvesting of corn ears and stalks. Specifically, the clamping and conveying device can effectively shorten the length of the harvest header. The vertical roller group can reduce the impact force between ears and picking rollers, even the picking loss. The stalks can also be cut in a centralized way. However, the current integrated device of clamping and conveying is often scratched on the surface of the plant stem by the sharp chain teeth, resulting in more broken stems on the harvest header. In this study, the clamping and conveying device was designed for the vertical roll-type header of the corn combine harvester, in order to achieve the smooth clamping and conveying of maize plants without damaging the stalks. The clamping and conveying channel were adaptively adjusted with the plant stem thickness, in order to improve the clamping stability with the low rate of broken stems in the clamping and conveying device of the vertical roll-type corn header. The device was composed of the reel chain and clamping and conveying mechanism. The reel chain mechanism was for the orderly feeding of individual maize plants, and the reciprocating cutter to complete the cutting of plant roots. The clamping and conveying mechanism was used to realize the effective clamping and conveying of cut plants on the vertical roll-type corn header. In addition, a fold line path of the clamping and conveying channel was formed under the joint action of large and small chain clamping pulleys, as well as the bilateral clamping and conveying chains. The clamping and conveying channel clearance was adjusted, when the stalk passed through the channel, according to the stalk diameter under the tensioning mechanism of the bilateral clamping and conveying chains. There was a more reasonable clamping force on the clamping and conveying mechanism, and a more reliable clamping and conveying, compared with the integral chain structure. An optimal combination was also achieved in the process of the toggle-feed in, grip-cutting, and grip-conveying, where the effective reel section chain length of the reel chain mechanism was 500 mm, the length of the clamping and conveying channel was 1 100 mm, the maximum clamping and conveying capacity of the harvest header was 3, and the vertical distance between the grip rails was 40 mm. Furthermore, the clamping and conveying channel between the two-reel chain was adjusted to 16～40 mm under the grip rail chain clamping pulley and the tension device. The response surface method (RSM) was used to analyze the effects of the forward speed of the harvest, the rotating speed of the drive sprocket, the angle of the harvest header, and the feeding angle of the plant on the operation performance of the clamping and conveying device. The test results showed that the total ear loss rate was 0.83%, and the broken stem rate was 0.12% when the forward speed of the harvest was 2.8 m/s, the rotating speed of the drive sprocket was 1 210 r/min, the angle of the harvest header was 18°, and the feeding angle of the plant was 60°. The total ear loss rate and the broken stem rate were reduced from 2.80% to 0.83% (30%), and from 0.98% to 0.12% (12%), respectively. This finding can provide the theoretical basis and technical reference for the high quality and low damage of vertical roll-type corn harvesting.