土壤耕作部件极窄刀齿与土壤作用关系研究

随着保护性耕作技术和低扰动土壤处理技术的发展,新型土壤耕作部件越来越多地采用窄类或极窄类刀齿形式。通过理论分析和室内土槽试验,对矩形齿和三角形齿两种极窄刀齿贯入土壤造成的土壤失效机理、刀齿工作时的主要阻力来源、刀齿形状尺寸参数对贯入阻力的影响以及刀齿贯入阻力预测模型进行了研究。结果发现,极窄刀齿在贯入土壤过程中,土壤与刀齿相互作用产生应力场和速度场,土壤主要受到刀齿的挤压而失效;刀齿所受阻力可以通过相互作用过程中产生的力学分量进行预测,特别是该预测模型能够较好地反映刀齿在不同深度下所受阻力的变化趋势,研究还发现在土壤参数一定的情况下,极窄刀齿所受阻力与刀齿和土壤的接触面积直接相关,极窄刀齿的形状尺寸参数是其受力的重要影响因素。

Interaction Relationship between Soil and Very Narrow Tine during Penetration Process

With the development of the conservation tillage technology and low disturbance soil treatment, new tillage tools like narrow or very narrow tines are applied more often. In order to provide theoretical supports for the design and optimization of tillage tools and key components, and enrich the theory system of soil-tool interaction, the very narrow tine-soil interaction was investigated, especially during the penetration process. Two tines with different cutting edge shapes were designed and a special test bed was set up based on the soil bin test bench as well. Soil failure mechanism was analyzed. The resistances of the two tines were recorded, analyzed and compared in the penetration stage. And the resistance prediction mechanical models were proposed. The mean resistance sources of the tines were found by analyzing the tines resistance mechanical models. The contact areas of the very narrow tines in different depths were measured and calculated by using the CATIA three dimensional design software, and the relationships between the resistances and contact areas were analyzed as well. Results indicated that soil failure was mainly caused by the stress field and velocity field in the soil-tine interaction. Mechanical components of soil cohesive, pressure, friction and adhesion were the main resistance sources of the tines. The forces between the tines and soil can be predicted by the soil mechanical components. The prediction models can well reflect the tendency between the resistances and the depth in the tines working processes. Furthermore, the results indicated that there was a nonlinear relationship between the resistance and soil-tine contact area with certain soil property parameters. The tine geometry parameter became an important influence factor of the resistance.