WEAR PATTERNS OF SOIL CUTTING BLADES

The paper presents the results of laboratory tests of the wear of soil tillage blades. The authors have developed an experimental unit with a linear-moving sample blade when interacting with an abrasive medium imitating the real soil. Physical properties of the abrasive medium can be changed by incorporating into the composition quartz particles, paraffin, ceresin, pulverized cement and other materials. The installation reproduces the operation of a blade shearing off soil particles of a loamy soil. The authors have obtained relationships between the inclination angle, the blade wear land width and length and the cutting path. As the depth of cutting increases, the wear rate increases in a parabolic manner. Due to the wavy irregularities of the furrow bottom, the wear rate decreases by 10...15%. It is caused by a load decrease of treated abrasive medium regardless of the blade material (steel or aluminum alloy). With the hardness of medium increases to more than 2 MPa, the blade wear rate increases, but the wear land angle to the furrow bottom decreases due to a changed wear mechanism. As fine dust particles concentration in abrasive medium increases, a facet formed on the blade edge contributes to its rapid blunting. As the cutting speed increases from 0.3 to 0.6 m/s, the blade wear rate increases by 25...30% due to raising soil resistance and the specific energy spent on soil deformation and destruction.

本论文呈现了土壤耕作刀片磨损情况的实验室测试结果。研究人员开发了一套配备直线运动试样刀片的实验装置，其刀片可与模拟真实土壤的磨料介质（abrasive medium）相互作用。该磨料介质的物理特性可通过在其组分中添加石英颗粒、石蜡、地蜡、粉碎水泥及其他材料进行调节。该实验装置可复现刀片剪切壤质土壤（loamy soil）颗粒的作业过程。研究人员得到了刀片倾角、磨损带（wear land）宽度与长度以及切削路径之间的关联关系。随着切削深度增加，刀片磨损速率呈抛物线型增长。由于犁沟底部存在波浪状不平整，磨损速率会降低10%~15%。无论刀片材质为钢材还是铝合金，该现象均由处理后磨料介质的载荷降低所导致。当介质硬度提升至2MPa以上时，刀片磨损速率上升，但由于磨损机制发生改变，磨损带与犁沟底部的夹角会减小。随着磨料介质中微细粉尘颗粒浓度升高，刀片刃口形成的磨蚀小平面会加速其钝化。当切削速度从0.3m/s提升至0.6m/s时，由于土壤阻力上升以及用于土壤变形与破坏的比能耗增加，刀片磨损速率会提升25%~30%。