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DIN 25201-4标准
The securing characteristics of bolted joints have a relevant affect on the operation availability of railway vehicles. Nevertheless they are still a significant problem for railway vehicle OEMs and rail operators today, because many commonly used bolt-securing elements emerged to be ineffective.
Therefore, a comprehensive research, financed by the rail industry, was done between October 2004 and December 2006. The aim was to systematically investigate the parameters that influence the loosening of bolts, and to develop a detailed norm procedure in order to evaluate the performance of securing elements.
The initiators of this research were Alstom LHB Salzgitter, Bombardier Transportation Henningsdorf, Siemens Transportation Systems Krefeld, Deutsche Bahn Systemtechnik and three OEMs of securing elements including Nord-Lock GmbH, who were preselected by above-mentioned companies. The washers of Nord-Lock were the only tested securing elements based on wedge-locking function.
The analyses have been done by “IMA Materialforschung & Anwendungstechnik GmbH” in Dresden and by the Institute for product development and design engineering of the University of Applied Science in Cologne.
The influence of the eight parameters on the self-loosening of a bolted joint was systemically investigated through specific parameter studies, which were determined by means of test rigs.
By means of the assessment criteria according to DIN 25201-4, the overall assessment result is as follows:
All Nord-Lock wedge-locking washers (without any exception) which were tested according to DIN 25201-4:2010-01(E) Appendix B, have had a remaining clamping load of more than 80% after 2.000 cycles. The DIN Norm Committee released this Appendix B of the DIN 25201-4 in November 2010 for white print.
Based on this quantitative test result, the securing characteristics of the tested Nord-Lock cam washers are proven to be fully effective and are compliant to the test procedure according to Appendix B of the DIN 25201-4.
A work team of the initiating companies has accompanied the project and reviewed the research results regarding their pertinence for the joining technology and implementation into the DIN 25201-4. The period for formal objections regarding the draft of the DIN 25201-4 ended on September 30th, 2010. The official release by the DIN Norm Committee is imminent.
