凸轮机构的正、负偏置在教学中的阐释

考虑凸轮机构的正、负偏置涉及内容繁杂、教材及其它教学资源对此少有述及,学生无法灵活应对该知识点等问题,文章对此进行深入研究。首先,以偏置直动从动件盘形凸轮机构为研究对象,分析推程及回程压力角的特点并给出凸轮机构压力角的两种表达式;其次,从减小推程压力角以提高传力性能的角度,分析凸轮机构的合理偏置方式;最后,定义凸轮机构的正、负偏置。上述提供了凸轮机构合理偏置的清晰思路,对正、负偏置的全面理解及应用给予了切实的理论依据。

As positive&negative offset of cam mechanism is related to complicated contents,the explanations of it seldom appear in textbooks and other available teaching materials,college students usually have difficulties in understanding and flexibly applying of it,this paper carries out an intensive research on offset of cam mechanism and its related problems.Firstly,taking the plate cam mechanism with offset translating follower as research objects,the pressure angle for actuating and return travelis respectively analyzed,meanwhile,two formulas expressing pressure angle are derived.Then,reasonable offset style of cam mechanism is obtained according to reducing pressure angle for actuating travelso as to improve the force-transmission characteristics.Finally,the positive&negative offset of cam mechanism frequently confused by most learners is defined.The above provides clarity of thought about reasonable offset style of cam mechanism and concrete theoretical basis for comprehensive understanding and application of positive&negative offset of cam mechanism.