打结器咬绳机构线接触凸轮设计与载荷分析  

Line-contact Cam Design and Load Analysis of Rope-biting Mechanism of Knotter

作　　者：尹建军[1] 陈亚明[1] 张万庆[1] 

机构地区：[1]江苏大学现代农业装备与技术教育部重点实验室,镇江212013

出　　处：《农业机械学报》2016年第7期224-231,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51375215);镇江市重点研发计划项目(NY2015009);江苏高校优势学科建设工程资助项目(苏政办发(2014)37号)

摘　　要：针对打结器咬绳机构钩钳受载大、滚子磨损严重的问题,通过对咬绳机构的运动学分析建立了圆柱凸轮轮廓曲面的计算模型,使滚子与凸轮保持线接触的同时钩钳以正弦加速度规律张合。对咬绳机构进行力学分析并结合压簧压缩量和捆绳拉力测试,解析求解钩钳在咬合位置的静力学模型,得出钩钳咬合力的最佳变化范围为300.64～329.89 N。解析求解钳咬机构的动力学模型得出,当钩钳咬合力处于最佳变化范围时,圆柱凸轮的接触力介于240～330 N之间,其峰值可以用于检验滚子的接触疲劳强度,指导钩钳和滚子的材料选择。打结器样机捆扎5 000捆稻麦秸秆的田间试验发现,按预设的压簧压缩量7.5 mm和捆绳初始拉力35 N,钩钳尾部的滚子没有明显磨损,表明钩钳的咬合力控制合适,线接触凸轮改善了滚子的接触受载情况,达到了抗冲击和耐磨的设计要求。Aiming at the problem of rope-biting hook under heavier load and serious abrasion of its roller in rope-biting mechanism of knotter,a calculation model of curved surface of cylindrical cam was built up by analyzing the kinematics of rope-biting mechanism in order to make the roller and cylindrical cam keep line-contact as well as rope-biting hook open and close according to sin acceleration law. By carrying out dynamic analysis of rope-biting mechanism and combining with the test of compression amount of compressing spring and tensile test of the rope,the statics model of rope-biting hook on the position of holding on to the rope was solved analytically,and optimum range of holding-on force of rope-biting hook was obtained which value is between 300. 64 N and 329. 89 N. The dynamic model of rope-biting hook was also solved analytically,and the contact force of cylindrical cam was between 240 N and 330 N when holding-on force of rope-biting hook is within optimum range. The peak value of contact force of cylindrical cam may be used to check contact fatigue strength of the roller,and guide material choice of the rope-biting hook and its roller. The field tests showed the roller installed on the rear of rope-biting hook didn＇t have obvious abrasion after the kontter prototype finished 5 000 bundles of rice and wheat straws according to predetermined preload force of compressing spring and initial pulling force of the rope. The result showed that the holding-on force of rope-biting hook was controlled suitably and linecontact cam improved contact load of the roller,which met the design requirement of impact resistance and anti-friction.

关 键 词：打捆机 打结器 圆柱凸轮 机构设计 载荷分析 

分 类 号：S225.22[农业科学—农业机械化工程] TP391.9[农业科学—农业工程]