基于最优动态滑切的被动式锯齿圆盘防堵装置设计与试验

Design and Experiment of Anti-blocking Device Passive Sawtooth Disc Based on Optimal Dynamic Sliding Cutting

摘要:

针对东北地区玉米免耕播种时被动式防堵装置难以兼顾切断效果与作业载荷的问题，基于动态滑切原理设计了一种被动式锯齿圆盘防堵装置，在充分应用滑切减阻效应的同时可有效提高秸秆切断效果。根据锯齿圆盘动态滑切特性构建了动态滑切转换模型，开展了支撑切割下玉米秸秆锯齿滑切特性试验，得到了锯齿结构下最优动态滑切角为15°~30°，针对在锯齿结构下所产生的两种特殊切割过程及力学曲线，假设锯齿前角对于接触切割过程产生影响，在此基础上对圆盘锯齿结构参数进行设计，结合土槽试验及离散元仿真试验对假设进行了验证。开展二次回归旋转正交试验，得到锯齿结构最优作业参数为：前进速度2.0m/s、锯齿前角21.3°、齿高6.0mm。根据仿真结果完成圆盘加工并开展田间试验，试验结果表明：当秸秆覆盖量为1.97kg/m2、作业速度2.0m/s时，锯齿圆盘秸秆切断率为76.2%，峰值下压力为875.7N，平均下压力为544.1N，通过对平面圆盘进行锯齿结构设计，切断率提高34.7个百分点，峰值下压力和平均下压力降低5.7%、7.9%。圆盘作业性能良好，满足东北地区免耕播种要求。

Abstract:

In order to solve the problem that it is difficult for the passive anti-blocking device to take into account the cutting effect and the operation power consumption during no-tillage sowing of corn in Northeast China, a passive disc antiblocking device was designed based on the principle of dynamic sliding cutting characteristics of the sawtooth disc, which could effectively improve the straw cutting effect while fully applying the sliding cutting effect. According to the dynamic sliding cutting characteristics of the sawtooth disc, a dynamic sliding cutting and structure conversion model was constructed, and the sliding cutting characteristics of the sawtooth of corn straw under support cutting were carried out. The conclusion that the optimal dynamic sliding cutting angle under the sawtooth structure was 15°~30°, and the hypothesis of the influence of the sawtooth rake angle on the two types of cutting process was put forward for the two special cutting processes and load curves generated under the sawtooth structure, and it was verified by combining the soil groove test and the discrete element simulation experiments. The quadratic regression rotational orthogonal experiment was carried out to determine the optimal operating parameters of the sawtooth: the forward speed was 2.0m/s, the sawtooth rake angle was 21.3°, and the tooth height was 6.0mm. According to the simulation results, the disc processing was completed and the field experiment was carried out. The results showed that when the straw covering amount was 1.97kg/m2, the sawtooth disc straw cutting rate was 76.2%, the vertical peak downforce was 875.7N, and the average downforce was 544.1N, the sawtooth structure design of the planar disc was increased by 34.7 percentage points, and the peak downforce and average downforce were reduced by 5.7% and 7.9%. The disc operation performance was ideal, and it met the no-tillage sowing requirements in Northeast China, and can provide a theoretical reference for the research of cut-off anti-blocking device for no-tillage seeder.