NORRA technology for the repair of points and frame rails by automatic surfacing
Technology "NORRA" (Surfacing of Wits and Frame Rails Automatic) - is designed to restore worn-out wits of grade 1/6, 1/9 and 1/11 paired with frame rails of the R50 and R65 types in stationary conditions with automatic electric arc surfacing with self-shielding flux-cored wire.
The main goal achieved with the NORRA technology is resource saving, which involves the implementation of the following steps:
- Removal of worn out points and frame rails (ORR) from operating turnouts of grade 1/6, 1/9 and 1/11 of type P50 and P65 lying on the way and their delivery in sets to the repair site
- Restoration of ORR sets in stationary conditions using the NORRA automatic surfacing technology
- Their return to operation as part of repair kits for the corresponding types and brands of turnouts
The NORRA technology has successfully passed comprehensive tests at VNIIZhT JSC for compliance with the requirements of the Program and methodology PM-09-2018, as a result of which the corresponding Conclusion No. 2882 / SVT / 2022 of 05.03.2022 was received. The use of NORRA technology is carried out according to the following regulatory documents: - Specifications TU 24.10.75–386–01124323–2022 “Wits of turnouts of grades 1/6, 1/9, 1/11 paired with frame rails, repaired in stationary conditions by welding with electric arc by automatic method according to NORRA technology" - Technological instruction TI-01/2019-NSP "Surfacing of repair kits of sharp points and frame rails of turnouts in stationary conditions in an automatic way. Technological Instruction” The NORRA technology is implemented in stationary (workshop) conditions on a special universal stand that ensures the working position of the wits and frame rails during their operation on the way as part of turnouts of grades 1/6, 1/9 and 1/11 with rails of the P50 and P65 (photo 1).
Stationary conditions make it possible to ensure high quality and productivity of repairs due to the automation of the surfacing process, multi-stage control at all stages of repairs, as well as complete independence from weather conditions and train traffic, which is extremely difficult or impossible to organize on the way at an operated turnout.
Sets of wits and frame rails of turnouts of the R65 and R50 types of grade 1/6, 1/9 and 1/11 are accepted for repair, corresponding to wear of I-III degree of suitability in accordance with section 6.3 "Instructions for the use of old-year materials of the track structure", approved . Order of Russian Railways dated February 10, 2012 No. 272r (as amended by order of Russian Railways dated March 24, 2014 No. 715r). At the same time, the technology makes it possible to restore wear to a greater extent than is defined in the document for the III degree of suitability of turnout elements. In practice, wear parameters are determined rather by the economic feasibility of their repair, and are up to about 6-8 m in length and up to 12-14 mm in wear depth, with chipping up to 600-800 mm long.
The technical limitation on the application of the NORRA technology is the defectiveness of the rails, defined in the TS and TI for the technology: wits with defects with codes: DO.20.2, DO.26.3, DO.56.3, DO.61.2, DO.65.2, DO .66.3 in accordance with the "Classifier of Defects and Damages of Turnout Elements", (reg. of Russian Railways dated September 27, 2019 No. 2143r), as well as frame rails with a defect DR.21.2 and defects with codes: 10.2, 11.2, 12.2, 14.2, 20.2, 21.2, 22.2, 24.2, 30.2, 31.2, 33.1, 50.2, 53.1, 55.1-2, 60.1-2, 64.1-2, 65.1-2, 69.2 in accordance with the instruction “Rail defects. Classification, catalog and parameters of defective and sharply defective rails ”(registration of JSC Russian Railways dated October 23, 2014 No. 2499r). Critical for surfacing is also the presence on the tread surface and the working face of a network of microcracks of great depth and length.
The main stages of the repair process:
- Troubleshooting of a set of OPP, determination of repair areas and parameters for restoring wear of rails by surfacing.
- Abrasive grinding of repair areas to prepare the metal surface for surfacing.
- Creation of a compensating bend of the welded rail.
- Preliminary induction heating of the repair area.
- Performing automatic surfacing with support heating.
- Removal of the compensating bend and preliminary grinding.
- Finishing grinding of the point and frame rail in the gouging zone with control of the profile of the frame rail and point rail in standard sections, parameters of straightness and fit of the point to the frame rail.
- Acceptance control and marking.