Development and localization of a manufacturing technology for cast center plates for 1520 mm gauge freight wagons

Abstract

The present study addresses the scientific and engineering problem of developing and localizing a manufacturing technology for cast center plates for freight railway wagons operating on 1520 mm gauge railways, based on the production facilities of JSC “Foundry and Mechanical Plant” (Tashkent). The relevance of the research is determined by the need to establish local manufacturing of safety-critical freight wagon components using the available production equipment and commercially available grades of cast steel while ensuring compliance with the requirements of the applicable regulatory and technical documentation. According to GOST 34468-2018, the manufacture of cast center plates and center-plate seats is specified using steel grades 20FL, 20G1FL, 20GL, 20L, and 25L in accordance with GOST 977. For steel grade 25L, the carbon content shall not exceed 0.25%. The mechanical properties of cast center plates shall comply with the requirements of GOST 977. For cast center plates manufactured from the specified steel grades, the bearing and thrust surfaces shall have a hardness of at least 143 HB. In the present study, steel grades 20L and 25L are considered as the primary materials for localized production. These grades are characterized by lower cost compared with 20FL, 20G1FL, and 20GL, provided that the finished components meet the requirements of GOST 34468-2018 and GOST 977. The selection of a casting process is обусловлен by the absence of dedicated forging or stamping facilities for center plate production at JSC “Foundry and Mechanical Plant” and by the availability of an operating foundry capable of manufacturing center plates in sand-clay moulds. The technological capabilities of the plant include a 6-ton-capacity induction furnace manufactured by Otto Junker, an automatic moulding line manufactured by Kunkel Wagner, a normalizing furnace manufactured by JSC “Kerammash,” laboratory equipment for quality control of the metal and finished castings, as well as metal-cutting equipment for subsequent machining operations. The objective of the study is to develop and provide a scientific and engineering justification for a localized manufacturing technology for cast center plates made of steel grades 20L and 25L using the existing production facilities of JSC “Foundry and Mechanical Plant” while ensuring compliance with the requirements of GOST 34468-2018. Particular attention is paid to the selection of the appropriate steel grade, optimization of the gating and feeding system, ensuring adequate mould filling and controlled solidification of the casting, minimizing the risk of casting defects, development of appropriate heat-treatment parameters, and experimental verification of the manufactured components against the applicable regulatory requirements.