Investigation of the Functional Mechanisms of PTFE Lip Seals

PTFE 唇形密封件功能机制的研究

• 批准号: 262224054
• 负责人: Professor Dr.-Ing. Werner Haas
• 金额: --
• 依托单位: Institut für Maschinenelemente (IMA)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/262224054?language=en
• 关键词: Investigation; Functional; Mechanisms; PTFE; Lip

The common solution for sealing shafts in mechanical engineering is the radial lip seal made of elastomer. Since elastomeric radial lip seals relatively quickly reach their load limits, lip seals made of PTFE compounds are increasingly used in sealing technology. By utilizing PTFE (polytetrafluoroethylene) as sealing material the limitations of elastomers can be largely overcome. PTFE can withstand operating temperatures from -200°C to 250°C and has an almost universal chemical resistance. In addition to that PTFE has good dry running capabilities and a low coefficient of friction on technically relevant counter surfaces. For lip seals PTFE compounds (filled PTFE) are used to further improve the properties of PTFE.PTFE lip seals not only can replace elastomeric radial lip seals in critical sealing applications, but sometimes even may be used instead of relatively complex and expensive sealing systems such as mechanical seals. This allows the use of PTFE lip seals as universal seals in numerous cases which increases the operational reliability, improves the emergency operating features, eliminates the risk of fluid intolerance and reduces or even avoids downtime due to seal failures.Despite the enormous potential benefits for seal users through the availability of optimized PTFE lip seals, there is little progress by the seal manufacturers. This is mainly due to insufficient understanding of the functional mechanisms of PTFE lip seals. Without knowing the exact functional mechanisms a directed optimization is not possible. Therefore optimization can only be achieved through high experimental effort by trial and error.The aim of this research project is to resolve this drawback by conducting and publishing a comprehensive analysis of the static and dynamic functional mechanisms of PTFE lip seals.An important research method in this project is the numerical simulation of the flow processes in the sealing gap and sealing gap area. In particular the involved microscopic flow processes are considered because only thereby the elasto-hydrodynamic sealing gap is formed. Additionally the interaction of the macroscopic and the microscopic flow processes is studied. The findings from the simulations are validated and extended experimentally and are necessary for the derivation of the dynamic functional mechanisms of PTFE lip seals.Another important feature of this project is to study the interfacial effects in and around the sealing gap. These investigations are carried out experimentally and are primarily aimed at understanding the static functional mechanisms. Furthermore it is investigated whether interfacial effects have an impact on the dynamic functional mechanisms.

机械工程中常用的密封轴解决方案是弹性体径向唇形密封。由于弹性体径向唇形密封件相对较快地达到其负荷极限，因此由聚四氟乙烯化合物制成的唇形密封件越来越多地被用于密封技术中。通过使用聚四氟乙烯(PTFE)作为密封材料，可以在很大程度上克服弹性体的局限性。聚四氟乙烯可以承受从-200°C到250°C的工作温度，并且几乎具有普遍的耐化学性。除此之外，聚四氟乙烯具有良好的干式运行能力，在与技术相关的台面上具有较低的摩擦系数。对于唇形密封件，使用PTFE化合物(填充的PTFE)来进一步改善PTFE的性能。PTFE唇形密封件不仅可以在关键的密封应用中取代弹性径向唇形密封件，有时甚至可以用来取代相对复杂和昂贵的密封系统，如机械密封。这允许在许多情况下使用PTFE唇形密封件作为通用密封件，这提高了操作可靠性，改善了紧急操作特性，消除了流体不耐受的风险，减少甚至避免了由于密封故障而导致的停机时间。尽管优化的PTFE唇形密封件的可用性为密封用户带来了巨大的潜在好处，但密封制造商几乎没有取得什么进展。这主要是由于对聚四氟乙烯唇形密封件的作用机理了解不足。如果不知道确切的功能机制，定向优化是不可能的。因此，只有通过反复试验才能实现优化。本研究项目的目的是通过对聚四氟乙烯唇形密封的静态和动态作用机理进行全面的分析来解决这一缺陷。本项目的一个重要研究方法是对密封间隙和密封间隙区域的流动过程进行数值模拟。特别是，考虑了所涉及的微观流动过程，因为只有这样才形成了弹性流体动力密封间隙。此外，还研究了宏观流动过程和微观流动过程的相互作用。模拟结果得到了实验的验证和推广，对于研究聚四氟乙烯唇形密封的动态作用机理是必要的。本项目的另一个重要特点是研究密封间隙内部和周围的界面效应。这些研究是通过实验进行的，主要目的是了解静态作用机制。此外，还研究了界面效应对动力学作用机制的影响。