冲击攻丝系统中高聚物材料缓冲性能的研究

【作者】 李素敏；

【导师】 徐人平；

【作者基本信息】 昆明理工大学 ， 机械设计及理论， 2004， 硕士

【摘要】 工程实际问题中，冲击现象的存在十分普遍，除了合理利用之外，由于冲击所带来的损失也是极为严重的，使用缓冲材料可以有效减缓冲击，对缓冲材料的缓冲性能进行研究优化，是一个很迫切的问题。冲击攻丝是近年来发展起来的一种攻丝方法，它的出现使螺纹的加工迈上了一个新台阶，它的广泛应用将会产生重大的经济效益。只是，这里还有一个关键的技术问题-需要应用缓冲垫对剧烈的冲击进行缓冲，缓冲垫起着保护装置不被损坏并协助装置回复的作用，缓冲垫的性能直接影响系统的运行，缓冲垫材料要求即强又韧。论文详细地分析了缓冲垫的重要作用以及缓冲垫材料选择的重要性。针对冲击攻丝系统缓冲垫材料性能的要求，对缓冲垫材料进行选材，缓冲材料中高聚物材料较其它材料的缓冲性能更加优越，所以选用高聚物材料作缓冲垫。高聚物种类繁多，性能各异，其中聚氨酯弹性体材料具有硬度范围大、弹性好、剩余变形量小等特性，比较适合缓冲垫材料。聚乙烯和聚氯乙烯分别具有冲击强度高、韧性好以及强度高的特征，也在某方面符合缓冲垫材料要求。因此论文选取了这三类材料与两种国外聚氨酯弹性体材料一起进行静态压缩试验性能测试。运用高分子材料的相关理论知识，从化学组成和物理结构的细节出发，用分子观点对试验材料的力学特征作了解释，重点探讨了聚氨酯弹性体的性能及影响性能的因素。并对材料的力学性能用宏观的描述进行了深入分析。通过试验，得出了应力-应变曲线、缓冲系数-应变曲线等应用曲线，根据试验曲线对材料的缓冲性能进行深入分析，并用分子观点进行解释。探讨了在缓冲应用方面聚氨酯弹性体材料与聚乙烯以及聚氯乙烯材料相比所具有的优越性。对三种聚氨酯弹性体材料在冲击攻丝系统上的应用情况进行分析：PU1最容易变形，寿命比较短；PU2比较适合冲击攻丝系统的冲压工况，它的缓冲性能较PU1好；PU3不但能够满足冲击攻丝系统的正常工况，在冲击攻丝系统承载更大压力时，该材料也可以适用。对聚乙烯和聚氯乙烯的缓冲性能也进行了探讨，它们不适合作冲击攻丝系统上的缓冲垫材料，并对它们所表现出的特性及应用作了分析。根据试验时试件的变形现象，对压缩过程中缓冲垫的形状和尺寸的变形规律进行了分析，鉴于现有试件压缩时力学性能不稳定，提出建议--根据冲击攻丝系统的结构设计对缓冲垫的尺寸进行调整。以提高缓冲垫的力学性能和使用寿命。最后，根据本论文所做的研究工作对今后仍需要探讨的方面进行了展望。更多还原

【Abstract】 There are a large amount of impact in engineering problems. Apart from its useful aspacts, it can bring about serious loss. Cushion materials can be used to relax impact, and it is a imperative problem to research the cushion properties of cushion materials.Impact tapping is one of tap methods that rises recently. Its rise make the produce of screw thread upgrade, and its abroad application can bring important economic benefits. But there is an important problemxushion is needed to relax the acute impact. The cushion helps to the protection and comeback of the system. The properties of the cushion have a direct relation with the running of the system. The need of cushion material is strong and tough. The important function of the cushion and the importance of the cushion material choice are nailed down in the paper..According to the need of cushion material, choice is made on cushion materials. Among cushion materials, macromolecule possesses outstanding cushion properties, so it is choosed. Among macromolecule materials, the cushion properties of polyurethane elastomers are outstanding very much, for example the higher rigidity, better elasticity and less remnent, and so on. Polythylenes possesses higher impact rigidity and excellent toughness, and polyvinyls possesses the higher rigidity. They can meet the cushion material’s needs. Then one kind of polyurethane elastomers, polythylenes and polyvinyls that made in China are choosed, then they are compressed statically with the other two polyurethane elastomers that made abroad.According to macromolecular theories, chemical compose and physical structure, explain the mechanics properties with molecule viewpoint, the relations between molecule sructure and properties of polyurethane elastomers are analyzed in detail. And the mechanics properties are analyzed with macroscopical describe in the paper.The properties are tested, and from the results of the test some useful strain-stress curves, cushion coefficient-stress curves are atained. According to the experiment tests and analyses of test matterials, the superiority of polyurethane elastomers in the cushion application aspact is discussed comparing with polythylene and polyvinyl in the paper.The mechanics properties of the three kinds of polyurethane elastomers are contrasted, their application states on the impact tapping system are analyzed:PUl is more easier to be distorted, and its life is the shortest; PU2 is suited to the impacttapping, and its cushion properties are better than PU1; PU3 can not only meet the impact tapping’s needs, but can be applied on the higher impact conditions. The cushion properties of polythylene and polyvinyl are discussed. According to the results, a conclusion is gained that they are unsuitable for the impact tapping, and their characteristics and applications are analyzed.Based on the distortion phenomenon of samples when beening compressed, the distortion regularity of cushion’s shape and dimension are analyzed. An advice are suggested that the shape and dimension of cushion should be adjusted to improve the mechanics properties and life.In the end, the aspacts should be discussed in the future are prospected in this paper..更多还原