Using a tractor repair welding of cast iron pieces, in addition to the actual situation the appropriate choice of welding methods, but also note the following items:
First, the pre-welding welding welding welding parts of the former should be in and around all harmful impurities such as rust, oil, paint, etc. thoroughly cleaned; welding cracks if the weldment thickness less than 25 mm in diameter should be drilled only about 4 mm hole; some weldment process but also according to the requirements of selected wall thickness and groove type and so on.
Second, the choice of electrode diameter and the different types of cast iron should be used in the corresponding electrode; primarily on the basis of its diameter at the welding weldments to determine the thickness; White and death in order to prevent the generation of the fire organization, reduce the heat-affected zone , the current use of small diameter electrodes.
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Third, the polarity of the DC arc chosen, in order to avoid the penetration is too large, overheating and burn weldment, are using reverse polarity connection, that weldments - then the cathode, the anode electrode connected.
Fourth, the current intensity of choice to increase the current penetration is too large, welded metal components and impurities to the weld pool changes the diffusion properties; current is too small to affect the stability of the arc, easy slag, porosity and other defects; current intensity selection should be based on cracks or defects in the welds steric conduction, taking also into account grades and electrode diameter.
V. welding operation points in order to reduce crack welding area should be avoided overheating, long cracks should be stopped, sub-stitch welding; to reduce penetration, should choose a small current, small electrodes, and as a short arc welding; for better welding of plastic such as nickel-based welding, metallurgy and welding, welding immediately after light tapping with a hammer round weld to weld stress relaxation, clear cracks and holes; not every small solder wave across the slope while on both sides, it is a good part of freedom of contract is not welding, and arc in the groove on both sides to avoid to stay too long; the bottom solder layer should cover the bottom of annealing, change to its processing performance.
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2011年9月13日星期二
2011年9月9日星期五
New technologies in steel welding applications
Steel structure with light weight, short construction period, adaptable, attractive appearance, easy maintenance, etc., its application more widely. The development of steel and steel production are closely related. China has become the world's steel-producing countries, steel production in China in 2005 exceeded 300 million tons, of which up to 140 million steel production, energy, transportation, metallurgy, machinery, chemicals, electricity, construction and infrastructure areas such as steel construction industry has become a pillar of national economy.
From the 1980s, the Chinese construction steel has been an unprecedented development, construction steel in the national economy plays a very important position. Basis to evaluate the amount of steel in 2005, about 11.55 million tons of steel building steel structure, more than 836 million tons in 2002 38%%. At present, China's top steel structure, steel structure, bridge steel, light steel and steel for residential steel and other industrial and civil buildings, springing up all over the country. According to statistics, so far, China has built more than 60 high-rise high-rise steel buildings; large-span space steel structure in a variety of stadium, exhibition center, theater, terminal, hangars and some industrial plants in the application; steel bridge in the ascendant, since the 1990s, according to incomplete statistics, Yibin section of the Yangtze River to Shanghai, the number has reached more than 50 bridges stabling block, half of them are steel bridge, "many among the 'World class' bridge, showing Chinese contemporary bridge technology has reached world advanced level "; After several years of intensive research and development into China's steel housing has a new stage of development, a group of the Ministry of Construction of the demonstration project, pilot projects and key technology research projects have been built and achieved scientific research, in the "circular economy" "green building" policies under the guidance of future housing construction steel in China will flourish.
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Welded steel construction features and difficulties
Looking at the current status of China's steel structure engineering and development trend, more and more with modern architectural style and architectural features of high technology, its main features are:
A novel and unique style, diverse architecture, the node structure is complicated, multi-form welded joints, component production and field installation of the welding technology more and more difficult. For example: National Stadium "Bird's Nest," a large number of steel works complex truss columns, the main truss, sub-structure node welding, weld criss-cross, the construction is very difficult.
2 building height is high, large span structures, seismic performance of welded steel design of the main requirements of high quality. Such as: frame beam-column connection weld, shear plate and column connection weld, beam web and column connections and column of the weld seam stitching, are the main parts of the structure, basically slope population penetration level seam, 100% ultrasonic testing, welding quality requirements are very high.
3 Use the varieties of steel specifications and more and more and more tend to use high-strength low-alloy structural steel and large thickness of the steel, iron and steel production process with increasing levels of, steel, austenitic stainless steel sheet has also been increasingly The more applications. Therefore, the required on-site pre-construction, the steel used for the delivery status, real-time for a new steel to the welding test, explore the science of welding parameters, welding technology to develop appropriate measures.
4 factory production and field installation link many factors, many different types of cross-operation, on-site installation difficult.
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From the 1980s, the Chinese construction steel has been an unprecedented development, construction steel in the national economy plays a very important position. Basis to evaluate the amount of steel in 2005, about 11.55 million tons of steel building steel structure, more than 836 million tons in 2002 38%%. At present, China's top steel structure, steel structure, bridge steel, light steel and steel for residential steel and other industrial and civil buildings, springing up all over the country. According to statistics, so far, China has built more than 60 high-rise high-rise steel buildings; large-span space steel structure in a variety of stadium, exhibition center, theater, terminal, hangars and some industrial plants in the application; steel bridge in the ascendant, since the 1990s, according to incomplete statistics, Yibin section of the Yangtze River to Shanghai, the number has reached more than 50 bridges stabling block, half of them are steel bridge, "many among the 'World class' bridge, showing Chinese contemporary bridge technology has reached world advanced level "; After several years of intensive research and development into China's steel housing has a new stage of development, a group of the Ministry of Construction of the demonstration project, pilot projects and key technology research projects have been built and achieved scientific research, in the "circular economy" "green building" policies under the guidance of future housing construction steel in China will flourish.
cable trays wire mesh, wire basket cable tray, outdoor cable tray
Welded steel construction features and difficulties
Looking at the current status of China's steel structure engineering and development trend, more and more with modern architectural style and architectural features of high technology, its main features are:
A novel and unique style, diverse architecture, the node structure is complicated, multi-form welded joints, component production and field installation of the welding technology more and more difficult. For example: National Stadium "Bird's Nest," a large number of steel works complex truss columns, the main truss, sub-structure node welding, weld criss-cross, the construction is very difficult.
2 building height is high, large span structures, seismic performance of welded steel design of the main requirements of high quality. Such as: frame beam-column connection weld, shear plate and column connection weld, beam web and column connections and column of the weld seam stitching, are the main parts of the structure, basically slope population penetration level seam, 100% ultrasonic testing, welding quality requirements are very high.
3 Use the varieties of steel specifications and more and more and more tend to use high-strength low-alloy structural steel and large thickness of the steel, iron and steel production process with increasing levels of, steel, austenitic stainless steel sheet has also been increasingly The more applications. Therefore, the required on-site pre-construction, the steel used for the delivery status, real-time for a new steel to the welding test, explore the science of welding parameters, welding technology to develop appropriate measures.
4 factory production and field installation link many factors, many different types of cross-operation, on-site installation difficult.
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