One of the key issues facing rail maintenance crews today is the successful identification and removal of rail corrugations (a sinusoidal, longitudinal rail surface deformation). Typically, rail corrugations are identified through visual inspection (which look for regular surface patterns) or audio methods (which listen for high frequency noise). Once identified, removal is accomplished through rail grinding and consists of running standard “peak-and-plow” grind pattern(s), whereby the corners of the rail are angled upwards to peak the rail, then the top of the rail is ground down (plowed) by placing numerous stones around the top of the rail. “Peak-and-plow” corrugation removal can require multiple passes depending upon the depth of the measured corrugation as well as the type of grinder (available horsepower) and the number of stones present on the grinder being utilized. The above methodology is typically applied whenever corrugation removal is required and since the grind patterns are static, significant extraneous metal removal can occur both during corrugation removal and during rail profiling.
An integrated system has been developed to identify and aid in the removal of rail corrugations. To assist in the detection and understanding of the severity of corrugations in the rail, a bogie frame mounted, accelerometer based measurement system was developed. The measured accelerations are filtered and transformed into displacement measurements which can be further processed to understand the primary wavelength and amplitude of the corrugations. These values can then be fed into specialized grinder control software which makes decisions on how to proceed with grinding; be it to remove corrugations then establish profile, only reestablish profile, or do nothing. Note that grinding may still be required to repair the rail surface due to other deformation such as rolling contact fatigue, shelling, spalling, etc. If corrugation removal grinding is required, the specialized software will create (in real-time) dynamic “peak-and-plow” grind patterns utilizing calibrated metal removal equations which estimate the amount of material one grinding stone can remove, based on the instantaneous radius of the rail, grinding motor horsepower, grinder speed, etc. The site specific, dynamic corrugation removal pattern contains calculated motor powers and orientations (angles) which will remove metal from the rails in such a way to both minimize metal removal required to eliminate the corrugations and minimize metal removal when establishing the desired post-grind rail profile.
This paper explores recent developments in the identification and subsequent managed removal of rail corrugations with an end goal of the reestablishment of rail profile with minimal metal removal and maximum preservation of rail life. The principal behind the corrugation identification system is described with supporting experimental evidence. Also presented in this paper are the basis behind dynamic corrugation removal, modeling results of applying a dynamic “peak-and-plow” pattern, and a comparative study describing the simulated post-grind outcomes of applying dynamic corrugation removal versus applying traditional methods.