The design of the cutting device of a walk-type pasture reaper was improved to solve the problems existing in using mono-acting cutter, such as the poor balance, the low cutting speed, the easily to be blocked, the difficulty to cope with the soft forage. The improved design applied the double-acting cutter device, whose double-acting cutter cut reversely each other driven by a double-camshaft linkage. Based on the kinematic analysis of the cutting device, this paper calculated separately the relationships of the angle of crank with the displacement, the velocity and the acceleration of knifes, and performed optimal design of the structural parameters of blades and the cutting clearance. By analysis of the cutting speed ratio, this paper also drew the cutting graphs of the double-acting cutter under different cutting speeds ratios. And it showed that in order to reduce the repeated cutting area and the fail to cut area, the optimum cutting speed ratio (K) is 1.6. The research provided references for the further optimal design and experiment of the cutting device of the walk-type pasture reaper.%为了解决小型牧草收获机单动刀工作时存在的平衡能力差、切割速度低、容易卡滞堵塞、难以适应柔性茎秆牧草的问题,进行了小型牧草收获机切割装置机构的改进设计；采用了双曲柄连杆机构带动两组刀片彼此反向切割的双动切割装置机构；通过其运动分析,得到了割刀位移、速度、加速度与曲柄转角的关系,并对动刀片结构参数和动刀间隙进行了优化设计.通过双动割刀切割速比的分析,绘制了不同切割速比下的双动割刀运动切割图,表明减少重割区和漏割区面积的最佳切割速比为K=1.6.研究结果为牧草切割装置的进一步优化设计和试验提供了参考依据.
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