Study On The Welding Technology For The Stainless Steel Roof Structure Of The Urban Railway Carriage

The Urban Railway traffic is the primary method of solving the large city traffic problem. With the rapid increasing of city population and the continual increasing of the pressure for perfecting environment, the demand of Urban Railway Carriage in our country is coming to the period of increasing fast. The Stainless Steel Urban Railway Carriage has become the fitted selected equipment in all kinds of Urban Railway Carriages. Only can we master the manufacture technology of the stainless steel car body in Railway Carriage Manufacture of our country, we would make the famous brand production with our intellectual asset in the form of copyright and patent. The study on the welding technology for the stainless steel roof structure of the urban railway carriage is the important part of studying and developing for the stainless steel car body, there is important and instructional significance for all kinds of stainless steel Railway Carriages car body in the future. In China, we select the main material of the stainless steel roof structure according to the Japanese stainless steel material standard; we choose the high intensity SUS301L series material with low carbon. The 0Cr18Ni9 material of China can be used in the position without the high intensity demand, the SUS301L series material is produced through the method of the Cold Roll after solution-zing heat treatment. So that there are five kinds of different mechanical performance materials through controlling the Cold Roll Reduction in the Cold Roll. The SUS301L series material is a kind of material with low carbon, it may reduce the phenomenon of the lacking chromium inter-granular attack after the welding, but the heat distortion is big for the stainless steel welding. We should as possible as select the spot welding method in the stainless steel roof manufacture. Not only there are the differences in mechanical performance in the SUS301L series material, but also there is more different distinction for the requirement of welding technology, and the heat can reduce the mechanical performance for the high intensity SUS301L material. The design of production should select pertinently the different tensile material according to the demand of design structure and manufacture technology. There are several parts make up from in the stainless steel roof; they are the arc roof part, the flat roof part, the connection part of the arc roof part and the flat roof part, the accessory. The stainless steel roof structure is designed overlap structure suited for spot-welding mostly, because the spot welding method should been used. MIG welding is used in the position that it is difficult for using the spot welding method in the structure or reaching in for the spot welding equipment. The manufacturer must use the necessary technology methods in the manufacture procedure in order to reducing the welding heat distortion and the production quality effect of the blaze adjustment. Resistance spot welding is a kind of method of resistance heating, it form the nugget through assembling the welding components into overlap joint, and compressing them tightly between two electrodes, then passing the electrical current, melting the mother material metal used resistance heat. There are many influencing factors about spot welding, includes electrode material, the electrode shape of end panel, welding current, welding pressure and weld time etc. In actual manufacturing, you may select suitable electrode material and design suitable electrode structure according to the property of the welded material, product quality requirement, and actual used condition, as well as the factors such as the difficult or easy level of getting material. In the course of the stainless steel roof produced, this paper has chosen the type electrode of one body, tip type separated electrode, self-adjusted type electrode and special type electrode. The welding specification of spot welding is important research content ofthe stainless steel, the welding specification of spot welding includes welding pressure, welding current and weld time. But it is big that the welding current influences the nugget strength. It is suitable for using the strong specification in austenitic stainless steel spot welding; the plenty of welding practices and the numerical simulation in nugget forming of spot welding have confirmed the result. The material of various strength grade have been chosen with in design of the stainless steel roof, so the different strength grades material of stainless steel also form the various welding joints. During the production of the stainless steel roof, the paper adopts the different level methods of managing the welding joints according to strength for various welding joints. According to manufacture technology and the designable structure of production, we need to allocate all kinds of the welding equipments for the stainless steel roof production. The arc weld equipment must can be suitable for sheet welding; and the equipment of spot welding need to be designed specially according to manufacture technology and the design structure of production. According to the needs of production program, this paper has designed distributable scheme and the crucial, large collocated equipment scheme of the stainless steel roof manufacture process, there is 1 overlap seam welding machine in the corrugated sheet seam welding process, there are 1 " C " type weld gun, 1 "X" type weld gun and 1 big throat depth "C" type weld gun in flat roof composition process and arc roof composition process, there are 2 big and 2 little type " " weld guns in the arc roof spot welding process. According to the structure of design, the manufacture technology and the requirement of production program, the paper made the stainless steel roof manufacture technology. We use whole pre-setting camber technology for the stainless steel roof manufacture according to the design requirement of the monocoque stainless steel car body, and make use of lengthen manufacturetechnology of the stainless steel roof for eliminating the whole welding contract of the stainless steel roof. The whole lengthened manufacture technology is used for eliminate the whole contract of the stainless steel roof after welding. It is because the arc welding methods is used in the connection part of the arc roof part and the flat roof part, this paper use separate manufacture and whole assembly manufacture technology for improving the productivity. We design the device of preventing distortion of the stainless steel roof for keeping the rigidity of it; the device is satisfied with the requirement of the hanging, transmission, reverse and following procedure. The robot automatic spot welding technology is used for the welding procedure corrugated sheet of roof. It can improve the productivity. This paper designs the relevant assembly technology after ensuring the special assembly structure of the compulsive air exhausting duct in the arc roof part according to analysis the contrastive structure between Japan and China, the assembly technology simplify the procedure of manufacture. The reliable jig must be used for guarantee the all kinds of components and parts to make sure the location is accuracy in the manufacture procedure of the stainless steel roof, and the reliable jig must be able to fix reliably, besides it can control the welding distortion effectively to ensure the accuracy of the production after manufacture. According to the manufacture technology and the designable structure of production of the stainless steel roof in China, this paper suggests that the design scheme of the jigs for the flat roof parts, arc roof part and the device of preventing distortion of the stainless steel roof. The existent primary quality problem of resistance spot welding is lack nondestructive detection methods. So this paper makes a set of test method to manage the quality of spot welding quality on the stainless steel roof according to the Japanese relevant criterion. It also designs a new manufacture and management method of spot welding of test sheet in order to ensure the canonical management of the spot welding of test sheet.