设施蔬菜收获切割影响因素优化试验

Optimization experiment of influence factors on greenhouse vegetable harvest cutting

为实现设施蔬菜收获机在收获过程中具有最佳的收获效果,该文设计了SHQG-I型设施蔬菜收获切割试验平台,该试验平台可对各个因素有效工作范围进行调整,采用响应曲面试验法对收获过程中刀具切割蔬菜茎部的切割综合影响因素进行优化。该文以奶油生菜为研究对象,根据奶油生菜的生长状况及种植情况,对收获切割的过程进行了分析,选取设施蔬菜的切割部位、切割方式、切削速度、削切角度、夹持距离、夹持角度6个参数作为影响因素,切割力大小作为试验指标,设计了SHQG-I型设施蔬菜收获切割试验平台。利用响应曲面试验法进行了试验,并利用Design-expert软件对试验结果进行分析,确定最优的工作参数：切削速度675 mm/s,削切角度4.85°,夹持距离98.5 mm,夹持角度64.5°。最终确定最优参数下的理论切割力为17.9 N,实际切割力为17.4 N,保证了收获成功率100%的情况下,有效降低了收获过程中切割力3~8 N/棵。该研究结果将用于温室蔬菜收获机的改进,同时对设施蔬菜收获提供参考。

In the developed countries of the West, the greenhouse vegetable industry has become highly mechanized, with a relatively stable mechanization production system and necessary supporting tools. In order to improve the efficiency of harvesting greenhouse vegetables, Beijing University of Technology has designed an innovative vegetable harvester. The cutting tool that is used to remove vegetables from their stems is a critical factor in greenhouse vegetable harvesting and must be optimized to ensure that greenhouse vegetables are harvested effectively. The designed machine can have a better harvest effect and reduce the wear of cutting tool in the process of the work. At present, the mechanical properties of stem-cutting factors affecting crops have been extensively studied with sugar cane, corn stalk, eulaliopsis binata stem and cabbage in China and abroad. This paper detailed the design and study of the SHQG-I greenhouse vegetable harvest cutting experiment platform, which used a response surface method（RSM） to optimize the harvest process through a comprehensive cutting tool that removed vegetables from their stems. The study object of this paper was butter lettuce; the experiment was carried out on the SHQG-I greenhouse vegetable harvest cutting experiment platform, and the working process of greenhouse vegetable harvester was analyzed. According to the butter lettuce growth and the working process conditions, 6 parameters of the harvest cutting process were analyzed： cutting position, way of cutting, cutting speed, cutting angle, clamping distance and clamping angle. Determining the ways in which these parameters affected cutting force was the target of the experiment. The working range of these factors, which could be adjusted on the SHQG-I greenhouse vegetable harvest cutting experiment platform, influenced the cutting force. For the RSM employed in the experiment, generally no more than 4 parameters would be adjusted at a time. Therefore, the experiment first used the factor-screening test to determine the cutting position and cutting way. The cutting position was at 7 mm and the smooth cutting angle was 10°. The results of the experiment were analyzed with the Design-expert software. In addition, the regression equation of the cutting force and the various factors were determined, and lack of fit of the regression equation was found to be insignificant. Next, variance analysis was used to determine the significant factors, which were cutting speed, clamp distance, interaction between cutting speed and cutting angle, and interaction between cutting speed and clamp distance. Then, the curve diagram of significant factors and the response surface figure were drawn. Ultimately, the optimal working parameters were determined： cutting speed was 675 mm/s, cutting angle was 4.85°, clamping distance was 98.5 mm and clamping angle was 64.5°. According to the optimization parameters, the expected cutting force was 17.9 N, and the actual cutting force was 17.4 N（2.8% less than the expected force）, which met the demand of the test. The experiment guaranteed a harvest success rate of 100% in all of the cases, as well as effectively reduced the necessary cutting force in the harvest process. After optimization, the harvester machine was in good condition, it produced a good harvest, and the cutting fracture was smooth, which satisfied the engineering requirement. The optimization parameters obtained in the experiment can be applied for the improvement of the actual equipment in the greenhouse vegetable industry field.