基于非均匀磨损调控的自磨刃犁铧设计及其耐磨性

    Design of self-sharpening plowshare based on non-uniform wear regulation and its wear resistance

    • 摘要: 针对翻耕犁铧因非均匀磨损导致的作业能耗增大、经济性和使用寿命降低的问题,该研究采用激光熔覆技术在犁铧下刃面制备耐磨复合涂层以形成自磨刃犁铧,并通过田间试验测试犁铧的耐磨性及自锐性。研究表明,普通犁铧由于上、下刃面受力差异导致犁刃快速钝化并失效;采用激光熔覆技术在犁铧下刃面制备Co-WC/MoS2耐磨复合涂层,通过调控涂层与基体的磨损率比,可使犁铧在磨损过程中保持良好自锐性,提高犁铧使用寿命。通过田间试验可知,当涂层与基体的磨损率比接近1:3.67时,背棱生长速率低于0.03 mm/hm2,自锐性能最优,使用寿命最长。涂层与基体的磨损率比过高或过低时,均会降低犁刃使用性能。该研究结果为长寿命自磨刃犁铧的设计与制造提供思路和方法。

       

      Abstract: Reversible plows are prone to uneven wear during cultivation, due to the complex and variable soil conditions, as well as high-intensity operational loads. High energy consumption of the tractors pulling can also shorten the service life of the reversible plows, thereby raising their operating costs. In this study, a self-sharpening plowshare was developed with high wear resistance using non-uniform wear regulation. Firstly, the wear patterns of the plowshare edge were investigated to determine the stress distribution in the three-sided wedge model. The force conditions on the plowshare edge were also obtained in the normal plane. The wear difference between the top face and bottom flank was calculated for a self-sharpening plowshare. According to the non-uniform wear characteristics of the plowshare, five sets of Co-WC/MoS2 wear-resistant composite coatings were prepared with different chemical compositions using laser cladding technology in the laboratory. The wear behavior of these coatings was tested using a multifunctional friction and wear testing machine. The wear rate ratio between the coating and substrate was then calculated for each sample group. Finally, three representative coating protocols were selected to fabricate the plowshares, along with a control group of untreated conventional ones. The field tests were carried out under extreme sandy soil conditions across 60 hm2 of cultivated land. The wear resistance and self-sharpening properties of the self-sharpening plowshares were evaluated to measure the plowshare width, edge thickness, and mass. Research indicates that the conventional plowshares were prone to rapid blade dulling and failure due to the differential stress distribution across their top face and bottom flank. The maximum wear difference between the conventional plowshare (Sample 1) and the self-sharpening sample (Sample 3) reached 14.02 mm after the wear and field tests. There was a great variation in the width during tests. The width loss rate at the front end of Sample 2 (0.08 mm/hm2) was 2.96 times that of Sample 3. While there were similar wear characteristics in the middle and rear sections. In plowshare edge thickness, Sample 1 exhibited the typical edge blunting after wear, with a 66.62% increase in the edge thickness after tilling 60 hm2. In contrast, the self-sharpening plowshares (Samples 2 and 3) shared the edge thickness reductions of 26.90% and 17.00%, respectively, over the same 60 hm2 tilling cycle. Although Sample 4 exhibited a low coating wear rate, its plowshare edge thickness closely matched the wear trajectory of uncoated Sample 1. In mass change, the self-sharpening plowshares demonstrated significant advantages during the 60 hm2 tillage cycle. Sample 3 (with a coating-to-substrate wear ratio of approximately 1:3.67) exhibited a mass loss rate of 7.98 g/hm2, while Sample 2 (with a coating-to-substrate wear ratio of approximately 1:2.38) shared a mass loss rate of 8.10 g/hm2. The superior performance was achieved compared with Samples 1 and 4. A comparison indicated that the blunt edge growth rate was controlled below 0.03 mm/hm2, when the wear rate ratio between coating and substrate was closest to 1:3.67 (as in Sample 3), indicating the optimal self-sharpening performance and the longest service life. Once the coating's wear rate was excessively high, the coating material failed to maximize the protection of the plowshare substrate. When the coating wear rate was too low, the prolonged wear caused greater top-layer abrasion than the bottom layer, thus thinning the plowshare edge for the fracture risk. The wear-resistant layer failed to fully exhibit its properties, similarly reducing the plowshare's performance. These research findings can provide the theoretical support and technical references to develop the high-performance plows. It is also of significant importance to advance the sustainable development of agricultural machinery.

       

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