控制钢轨接触焊灰斑的正交优化研究

Orthogonal Optimization Research on Controlling Grey Spots in Rail Resistance Welding

灰斑已成为无缝线路钢轨结构接触焊接头最突出的缺陷。灰斑的存在易导致接头的脆性断裂。因此，控制灰斑对保证钢轨接触焊质量举足轻重。由于钢轨接触焊接头灰斑与性能受众多参数综合影响，故采用正交设计安排试验。本研究搜集了各型钢轨接触焊的９套规范，分析了２７种工艺参数的共性与个性，运用正交设计的均衡分散性与整齐可比性原理对“Ｕ７４”型６０ｋｇ／ｍ钢轨进行正交焊接试验。首轮安排Ｌ２７（３１３）的大正交表，再根据与施焊结果对应的参数最优直观组合、最优位级组合与趋势更优位级组合继续安排下轮较小的正交表进行焊接试验，以较少的焊接次数优选出成套优佳焊接参数。在连续施焊的２５个焊接接头中灰斑都不超过标准允限，且落锤。

Grey spot has become the most conspicuous defect in resistance welding joint of the structure of continuous welded rail track.The existence of grey spot may cause brittle crack of the joint,therefore,controlling grey spot occupy a decisive position to ensure the quality of rail resistance welding.Because of that both the grey spots and the performances of the rail resistance welding joints are under the synthetical influence of many parameters,the orthogonal design was used to settle tests.In present research,9 sets of resistance welding parameters of different type of rails were collected,and the general and specific characters of 27 technological parameters were analyzed.Applying the principles of both the “balance and dispersion”character and the “regularity and being capable of comparing”character of the orthogonal design,the orthogonal welding tests were carried out to “U74”60 kg/m rail.The large orthogonal table L 27 (3 13 )was arranged in the lst round.According to the test results,the optimum complete set of parameters that is directly perceived,the combination of optimum position grades and the combination of position grades with better trend were used to arrange smaller orthogonal table to do the next round of tests.Through tests and analyses,the whole set of the excellent welding parameters has been obtained.Using this set of parameters,the authors achieved that not only the total area of grey spots was less than the standard tolerance in 25 rail joints welded successively,but also the results of dropping hammer tests and static bending tests came up to the standards.