1、 Position and function of arc stud welding technology in national economy

Arc stud welding machine is an advanced manufacturing technology. It has developed from a single processing technology to a new subject integrating modern science and technology, and has become a comprehensive engineering technology. It involves materials, structural design, pretreatment of arc stud welding machine, process equipment of arc stud welding machine, materials, blanking, forming, production process control and mechanized automation of arc stud welding machine Arc stud welding machine quality control, post weld heat treatment and many other technical fields. Arc stud welding technology has been widely used in various departments of industrial production. It plays an important role in promoting the development of industry, the technological progress of products and the development of national economy.

Arc stud welding technology is one of the key technologies of mechanical manufacturing and an indispensable processing method for the manufacture of many high-tech products. For example, the world's largest 1200kW thermal power unit, 700kW hydropower unit, 1300kW nuclear power equipment, 1200 ton hydrogenation reactor, launch vehicle of aerospace technology, spacecraft, space station and components of microelectronic technology are manufactured by arc stud welding technology. Without the use of arc stud welding technology, the manufacturing of these high-tech products will be difficult to complete.

Arc stud welding technology is the basis for ensuring product quality. Its technical level directly affects the quality and reliability of products. For example, there are more than 60000 joints of arc stud welding machine on the heating surface of a 600000 kW power plant boiler, more than 50000 joints of high temperature and high pressure arc stud welding machine for a 300000 kW thermal power unit, and 85000 joints for continuous installation. If one thousandth of the joints have quality problems, There are 85 hidden dangers, which directly threaten the safety of the power station. The main equipment of nuclear power, such as pressure shell, steam generator, voltage stabilizer, etc., are all arc stud welding structures. They are all in the primary circuit and subject to long-term effects such as radiation, high temperature and high pressure. If they are accidentally connected, the loss caused by leakage is unimaginable. Arc stud welding technology is an important means to save energy and materials and obtain economic benefits. For example, the hydropower unit of the Three Gorges project, which has attracted worldwide attention, has a single unit capacity of 700000 kW. Its turbine runner diameter is 9.8 meters and weighs 500 tons. It is spliced with dissimilar steel. Compared with the overall stainless steel runner, each unit can save 20 million yuan. A total of 26 units in the Three Gorges project can save 520 million yuan. Its economic benefits are very considerable.

2、 Characteristics of arc stud welder industry in China

Over the past 20 years of reform and opening up, with the further maturity of China's socialist market economy, China's arc stud welding industry has also made great development, especially the production technology of arc stud welding machine in large arc stud welding production backbone enterprises has been significantly improved. However, as far as the whole arc stud welding industry is concerned, there is still a large gap between China's arc stud welding technology and industrial developed countries, At present, China's industry has the following characteristics:

1. The proportion between the structure of arc stud welding machine and steel output is low

At present, the world engineering and technical circles have recognized that the amount of structural steel used by arc stud welding machine is the main index to measure the industrial development and advanced technology of arc stud welding machine in a country. Arc stud welding machine has become an important processing means in the manufacturing industry, especially in the equipment manufacturing industry. On average, 45% of the steel in the world is used for the structure of arc stud welding machine, while the steel consumption of arc stud welding machine structure in industrial developed countries has reached 60 ~ 70% of the steel output. In recent years, with the rapid development of China's industrial modernization, many heavy structures, such as power station boilers, pressure vessels, heavy machinery, ships and so on, have become large-scale, which has greatly increased the amount of structural steel for arc stud welding machine. At present, the amount of structural steel for arc stud welding machine in China has reached about 40% of the steel output, and there is still a certain gap compared with industrial developed countries.

2. The production mechanization and automation level of arc stud welding machine is low

In order to improve the production efficiency and reduce the labor intensity of workers, the production mechanization and automation of foreign arc stud welding machines have reached a high level. According to the amount of deposited metal, the mechanization and automation of arc stud welding machine has reached more than 65% in industrial developed countries, while it is only about 30% in China.

3. The production technology of arc stud welding machine is backward, and the proportion of manual welding is too large

Manual electrode arc welding is a traditional arc stud welding method with high energy consumption and low efficiency. It has been rarely used in industrial developed countries, but it is still widely used in China. According to the amount of deposited metal, it reached 71.4% in China in 2001 and only 15.5% in Japan in 1998. Gas shielded welding is an arc stud welding method with high efficiency, high quality, energy saving and material saving. It has been widely used abroad. According to the amount of deposited metal, it reached 77.6% in Japan in 1998, while it only accounted for 20% in China in 2001. Other high-efficiency and high-quality arc stud welding methods, such as electron beam welding, laser welding, plasma welding, arc stud welding robot workstation, arc stud welding flexible production system, narrow gap arc stud welding technology, double wire high-efficiency gas shielded welding technology, have been applied in China, but there is still a certain gap in the scope and level of application compared with industrial developed countries.

4. The product structure of electric welding machine is unreasonable, and the proportion of automatic and semi-automatic welding machines is low

In 2001, China's electric welding machine industry produced 303928 welding machines, of which manual arc welding machines accounted for 78.2%, while automatic and semi-automatic welding machines accounted for only 15.6%. In Japan, in 1997, manual arc welding machines accounted for 40%, while automatic and semi-automatic welding machines accounted for 29%. Inverter welding machine is a power supply for arc stud welding machine with excellent performance, which has been widely used abroad. The output of inverter welding machine has accounted for more than 30% of the total output of arc welding machine in the United States and more than 50% in Japan. In 2001, the output of inverter welding machine in China accounted for only 4% of the total output of arc welding machine.

5. The material structure of arc stud welding machine is unreasonable and there are few varieties

At present, China has become the world's largest producer of arc stud welding materials. The total output of arc stud welding materials has exceeded 1.2 million tons, which is the sum of the production of arc stud welding materials in the United States, Japan and Germany. However, the material and product structure of arc stud welding machine in China is unreasonable. In 2001, the output of welding rods in China accounted for 75% of the total output of arc stud welding materials, the output of gas shielded solid wire accounted for 12.9% of the total output of welding materials, the output of flux cored wire accounted for 0.96% of the total output of welding materials, and the output of submerged arc welding materials (including welding wire and flux) accounted for about 10.5% of the total output of welding materials. In 1999, the output of welding rods in Japan accounted for only 19% of the total output of arc stud welding materials, gas shielded solid wire accounted for 38% of the total output of welding materials, flux cored wire accounted for 31% and submerged arc material accounted for 12%. In contrast, the proportion of welding rod output in China is too high, while the proportion of materials for automatic arc stud welding machine is too low. In addition, the material variety of arc stud welding machine in China is single. For example, 90% of the welding rod production is structural steel welding rod, while some high-grade welding rods such as stainless steel welding rod, heat-resistant steel welding rod, low-temperature steel welding rod and cellulose welding rod used in pipeline engineering are very scarce, which can not meet the production needs. There are only 8 varieties of gas shielded solid core welding wire in the material product sample of arc stud welding machine, while there are 38 varieties of Shengang in Japan, 11 varieties of Lincoln company in the United States and 18 varieties of Issa company in Sweden. Among the varieties of flux cored wire, there are mainly several kinds of gas shielded flux cored wire of 500MPa grade for structural steel in China, while there are 79 varieties of flux cored wire in Kobe Steel in Japan and 93 varieties in McKay company in the United States. Due to the incomplete varieties and specifications of arc stud welding materials in China, a large number of arc stud welding materials need to be imported from abroad every year.

6. Arc stud welding enterprises have many manufacturers and small scale

At present, there are many arc stud welding enterprises in China, but the scale is very small. For example, the electric welding machine industry in 1995, there were about 1500 welding machine manufacturers and part-time manufacturers, auxiliary tools and components of arc stud welding machine. In the next few years, with the adjustment of the national economy and market competition, the number of enterprises has decreased. By the end of 2001, there are still 900 enterprises in the electric welding machine industry, including about 400 professional and part-time production enterprises of electric welding machine. In industrial developed countries, the scale of professional electric welding machine manufacturing enterprises is large, and there are only 3-5 enterprises in the United States and Japan. In the arc stud welding material industry, there are more than 700 arc stud welding material manufacturers, including more than 400 welding rod manufacturers and more than 150 gas shielded welding solid core welding wire manufacturers. China's arc stud welding enterprises cannot be compared with the world's largest arc stud welding companies in terms of scale. Taking flux cored wire manufacturers as an example, by 2002, there were 29 flux cored wire manufacturers in China, while there were only 12 in the United States, 18 in Japan and 8 in South Korea. Among the 29 enterprises in China, only 4 have an annual output of more than 1000 tons, while only one Sanying company has an annual output of more than 3000 tons. In 1997, Hyundai produced 3750 tons of flux cored wire, with an annual output of 45000 tons. In contrast, China is far from home.

7. The production technology of arc stud welding enterprises is backward, and the product quality needs to be improved

At present, due to the complex subordinate relationship of arc stud welding enterprises in China, most enterprises are relatively small, and the production technology, equipment and detection means are relatively backward. In the production of welding rod, the screw machine, oil press and wire cutter used are all consistent for decades. Due to the low level of automation, the improvement of the quality of welding rod is affected, such as the appearance quality of coating, eccentricity and the manufacturability of arc stud welding machine. In the welding machine manufacturing enterprises, a considerable number of enterprises still stay in the manual workshop and assembly processing stage or in the simple index detection stage. There is no perfect detection equipment, so that the service performance and quality of domestic welding machines can not meet the requirements of most domestic users. In 2001, ZX series arc welding rectifier, WS series TIG welding machine, NB series MIG / MAG welding machine and LG series air plasma cutting machine were spot checked, and the qualified rate of product spot check was only 56.5%, indicating that the quality of welding machine products in China needs to be further improved.

8. Insufficient investment in product development and weak scientific research force

Although the arc stud welding machine industry is an indispensable part of the national economy, the arc stud welding machine industry is not an important pillar industry and the enterprise scale is small. In addition, in recent years, some arc stud welding machine enterprises in China have poor economic benefits and are difficult to raise funds to develop new products. Enterprises are rarely able to obtain scientific research funding from the state or the government, so it is difficult to carry out scientific research and development entirely by relying on their own scientific research strength. Therefore, the products are aging and seriously lack competitiveness. In addition, in recent years, some scientific research institutes in China have carried out system reform, which has turned the institutions originally engaged in the technical research of arc stud welding machine into scientific and technological enterprises, and changed the work direction originally engaged in the research of arc stud welding machine, which has greatly weakened the scientific research capacity of arc stud welding machine in China.