立辊式玉米收获割台夹持输送装置设计与试验

针对现有立辊式玉米收获机割台夹持输送装置存在的夹持稳定性差、断茎率高等问题，该研究基于立辊式玉米割台摘穗特点，设计了一种夹持输送间隙随植株茎秆粗细自适应调节的夹持输送装置。该装置由分禾机构和夹持输送机构组成，分禾机构保证玉米植株的单株有序喂入，并辅助往复式切割器完成植株根部的切割；夹持输送机构实现切断植株在立辊式割台上的有效夹持和输送。通过对拨禾喂入过程植株的运动分析以及夹持切割和夹持输送过程植株的姿态变化规律分析，确定夹持输送装置有效拨禾段链条长度为500 mm，夹持输送机构轨道长度为1 100 mm，割台最大夹持输送量为3株，夹持轨道间的垂直距离为40 mm，两夹持链条间的夹持间隙可调节范围为16～40 mm。采用响应曲面法分析了收获机前进速度、主动链轮转速、割台倾角和植株喂入角对夹持输送装置作业性能的影响。试验结果表明，当收获机前进速度为2.8 m/s、主动链轮转速1 210 r/min、割台倾角18°、植株喂入角为60°时，果穗总损失率为0.83%，断茎率为0.12%；相比现有普通夹持输送装置，果穗总损失率和断茎率分别由2.80%和0.98%降低到0.83%和0.12%，分别降低了30%和12%。研究结果可为立辊式玉米收获割台的优化改进提供理论依据和参考。

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 grip and convey device can effectively shorten the length of the harvesting 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 grip and convey is often scratched on the surface of the plant stem by the sharp chain teeth, resulting in more broken stems on the harvesting head. In this study, the grip-convey device was designed for the vertical roll-type header of the corn combine harvester, in order to achieve the smooth gripping and conveying of maize plants without damaging the stalks. The grip and convey gap were adaptively adjusted with the plant stem thickness, in order to improve the clamping stability with the low rate of broken stems in the grip and convey device of the vertical roll-type corn header. The device was composed of the reel chain and grip-convey 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 grip-convey 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 grip-convey channel was formed under the joint action of large and small chain clamping pulleys, as well as the bilateral grip chains. The clamping channel clearance was adjusted, when the stalk passed through the channel, according to the stalk diameter under the tensioning mechanism of the bilateral griping and conveying chains. There was a more reasonable clamping force on the grip and convey mechanism, and a more reliable clamping 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 grip and convey channel was 1 100 mm, the maximum grip and convey capacity of the harvesting head was 3, and the vertical distance between the grip rails was 40 mm. Furthermore, the grip channel between the two-reel chain was adjusted to 15-25 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 harvesting head, and the feeding angle of the plant on the operation performance of the grip and convey 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 harvesting head was 18°, and the feeding angle of the plant was 60°. The total ear loss rate and the broken stem rate were reduced from 2.8% to 0.83% (30%), and from 1.3% 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.