Application And Research Of Self-propelled Air Pressure Welding Vehicle In Overhaul Construction Of Seamless Line

Nowadays the railway enters a new era of comprehensive promotion and application for continuously welded rail(CWR),and the CWR is the priority for the rail structure of either high speed railways or heavy haul railways.Hence,it has obvious advantages in technical economy.According to the statistics of some countries,the CWR can save 35%-75% of the rail maintenance cost when compared with the non-CWR structure in the respect of saving labor force and extending service life of equipment.In addition,characterized by good smoothness and stable travelling,the CWR is quite suitable for the operation of high speed and heavy haul trains.Besides,the operating cost of rolling stock can also be reduced.Hence,it is developed rapidly.In recent years passenger train speed and freight train load have been increased to enhance the efficiency of railroad transportation.These trends have increased the severity of the rail service environment as to wear resistance and fatigue damage resistance.Nippon Steel has met these challenges by developing high-performance and high-strength rails.Continuous welded rails(CWRs)have been increasingly laid to simplify track maintenance and inspection,control noise and vibration,and to ensure travel safety.Rail welding techniques are of the utmost importance for the laying of CWRs.The development and commercialization of new fusion welding techniques involving the novel idea of increasing the carbon content of the weld metal,a breakthrough in conventional welding technology,are described for in-track welding of high-performance and high-strength rails.The present status of automatic rail fusion welding technology expected to evolve further is introduced,and the future trends of rail welding are considered.The structure of China's CWR adopts the form of thermal stress.One type is the common CWR in which the buffer zone is connected to the adjacent long rail string.The other one is called super-long CWR,in which the long rail string is welded into the whole-region or cross-region CWR successively.With the promotion of bonded insulation,concrete turnout sleepers turnout,and weldable alloy steel combined frog,the technical bottleneck of super-long CWR is solved.The experience of super-long CWR management becomes increasingly mature,and the super-long CWR is often adopted in new rail overhaul.However,rail welding is one of the important links in CWR pavement engineering,and the quality of rail welding joint is related to the safety of railway train operation.In recent years,rail breakage in winter increasingly happens to the existing rails year by year,and rail breakage always occurs at the rail welding joint.According to the statistics,57% of the rail breakage occurs at the welded joint of thermit welding.At the construction site of CWR overhaul,gas pressure welding is one of the advanced rail welding methods in China.It canguarantee the rail welding quality at the construction site,and replace thermit welding to the largest extent.As for the self-propelled rail welding vehicle of YHGQ-1200 independently developed by China,the highly automatic rail welding machine of GPW-1200 is applied as the vehicle-mounted welder.Characterized by unique functions including automatic rail clamping,working edge alignment,welding,convex pushing by pressure maintaining,and normalization by pressure maintaining,this welder can meet the functional requirements for rail pulling,welding,normalization and forced cooling in the rail welding process of CWR.This vehicle model is the new self-propelled mobile rail welding vehicle greatly recommended for China's railway engineering system.Overhaul of rail change for the existing rails is influenced by factors like skylight time,line condition and construction environment,and the organization model of welded rail construction is complex.Therefore,it can provide important guidance for the overhaul of rail change for rail rails to study the welding quality and construction organization model of the self-propelled rail welding vehicle,so as to furthest meet the requirements for safety production and welding quality,and to increase the efficiency of field operation.By aiming at the overhaul of rail change for the existing rails of China Railway Lanzhou Group Co.,Ltd.,the author of this thesis studied the welding quality and construction organization model of the self-propelled mobile rail welding vehicle.First,the internal quality of the welding head was prevented and controlled through data debugging before the product entered the market.Secondly,the excellent weld appearance control scheme was summarized through exploration of appearance quality,and this scheme included two control measures,i.e.wire bond upward and wire bond downward.Thirdly,the optimum construction scheme suitable for CWR construction of China Railway Lanzhou Group Co,Ltd.was gained through optimization.This construction scheme included construction vehicle grouping for wire bond upward and wire bond downward of the self-propelled mobile rail welding vehicle,provision and organization of man-machine materials,construction process,security prevention and controlling,time node prevention and controlling,etc.The results show that this welding quality control scheme and construction organization model can guarantee the welding quality in a safe and superior way.Meanwhile,a pair of welding heads of wire bond downward and a pair of welding heads of wire bond upward can be completed with quality and quantity guaranteed,and a CWR of 1.5 km can be paved within the existing construction skylight in 210 minutes.The success of this study provides an excellent quality prevention and controlling measure and a set of perfect construction organization model for our group's self-propelled mobile rail welding vehicle to conduct CWR construction in the existing rails.