Investigation on influences on the service life of running ropes under reverse bending

与简单弯曲相比，反向弯曲对运行钢丝绳寿命缩短的影响目前大多未被研究。然而，在许多机械装卸机械的应用中，如电梯、起重机、索道或舞台机械，不可能完全避免反向弯曲，因此必须将其计入绳索传动的寿命计算中。最先进的标准和寿命计算方法在一般恒定系数的基础上考虑了运行钢丝绳在反向弯曲下的附加损伤。另一方面，在本研究方案提出之前，进行了文献研究以及在IFT弯曲机上进行的中试试验表明，由于股数、股数、绳力和滑轮与绳径比等多个参数的反向弯曲而导致的使用寿命缩短具有相关性。尤其是反弯滑轮的轴距对运行钢丝绳的附加损伤量有较大影响。进行的初步测试显示，与理论寿命计算的结果相比，存在显着差异，在许多情况下，这可能会导致重大安全风险。拟议的研究项目旨在进行基础研究，以开发可广泛使用的参数，以便在绳索传动的寿命计算中考虑钢丝绳在反向弯曲下的使用寿命缩短。特别是在什么情况下绳索可以“逃脱”由于反向弯曲造成的额外损害，以及在什么情况下绳索的额外损害高得不成比例，都要进行调查。科学调查的结果将增加反向弯曲绳索传动的可用性和安全性，并消除当今存在的安全隐患。现有的知识缺陷将被弥补，例如，在具有反向弯曲的绳索传动中，可能对绳索寿命的错误估计、安全风险以及针对服务和检查间隔的错误估计将在未来得到避免。对钢丝绳在反向弯曲下的损伤机理的了解可用于材料搬运的所有应用领域。

The influences of reverse bending on the reduction of service life of running ropes compared to simple bending is today mostly uninvestigated. Nevertheless, in many applications of mechanical handling machinery like elevators, cranes, ropeways, or in stage machinery, it is not possible to avoid reverse bending completely and therefore it has to be included into the lifetime calculation of the rope drives. State of the art standards and lifetime calculation methods take account of the additional damaging of running ropes under reverse bending on basis of a general constant factor. On the other hand, in advance of this research proposal conducted literature research, as well as pilot tests on bending machines of IFT showed dependencies of the service life reduction due to reverse bending of many parameters, e.g number of strands, lay, rope force and sheave to rope diameter ratio. Especially the axis distance of the sheaves under reverse bending evidently have great influence on the amount of additional damaging to the running rope. The conducted pilot tests revealed remarkable discrepancies compared to the results of theoretical lifetime calculation what in many cases can lead to major safety risks. The proposed research project aims on conducting basic research to develop widely usable parameters for taking the service life reduction of ropes under reverse bending into account for lifetime calculation of rope drives. Especially the circumstances under which the rope can “escape” the additional damaging due to reverse bending, but also the circumstances under which the additional damaging of the rope is disproportionately higher are to be investigated. The results of the scientific investigation will increase the availability and safety of rope drives with reverse bending and eliminate today existing safety risks. Existing knowledge deficits will be closed and for example possibly wrong estimations of rope lifetime in rope drives with reverse bending, safety risks and wrong estimations with view to service and inspection intervals will be avoided in future. The acquired understanding of the mechanisms of damage of the rope under reverse bending can be of use in all fields of applications of materials handling.