First, an overview of shipbuilding welding technology

As we all know, welding technology is one of modern engineering technology, is the 20's introduction, and to promote the development of shipbuilding welding technology, is now increasingly showing welding technology is the key to modern ship construction techniques. In the hull construction, hull construction welder at about 30% of total working hours to 40%, welded hull construction costs account for about 30% of the total cost of 50%. Ship welding quality is an important indicator of the quality of evaluation ship, weld quality and production efficiency and production quality also affect the cost of shipbuilding a major factor.

Now, with the continuous development of China's economic construction, China's shipbuilding industry is also competition in the market a major breakthrough in the export of ships. The level of the ship's overall design, capabilities and management tools to support overall improvement in export tonnage of the ship has reached the maximum single ship 300,000 tons of levels. Species not only bulk carriers, oil tankers, as well as reach the international advanced level of product tankers, chemical tankers and multipurpose vessels, the world's third largest shipbuilding country, but with the world advanced countries there is a gap. How to shorten the gap, catch up and surpass the advanced level of world shipbuilding, which is highly efficient welding technology application in ship construction, and promote the development of shipbuilding production of great significance.

Second, inverter welding in ship construction in the application

Arc welding is the most important shipyards, the most widely used welding process in the modern ship construction to obtain good welding quality, it must do to ensure good welding equipment. Inverter arc welding machine has good electrical properties and welding performance, it has the following properties and characteristics: ① control performance, easy to implement intelligent welding. ② move me good, excellent resistance welding process, is conducive to automation. ③ weight. ④ high efficiency, high power factor. ⑤ small. ⑥ arc performance can be achieved poor solder splash or no splash. ⑦ welding speed. ⑧ multi-function, and the conversion easy. As more inverter arc welding machine has several features and benefits, so is internationally recognized as the most advanced welding, also the most potential for development as a welder.

Promote the use of the shipyard welder IGBT inverter carbon dioxide and most realistic long-term technical and economic value. Since carbon dioxide is a highly efficient welding welding processes, welding quality, it can be asserted, semi-automatic welding of carbon dioxide, carbon dioxide and carbon dioxide welding robot automatic welding of carbon dioxide and other welding process will help an absolute advantage in shipbuilding.

The arc welding power source of carbon dioxide, in addition to considering the economy, reliability, usability and other general requirements, people are concerned about the electrical properties of the dynamic characteristics, because the dynamic characteristics of the carbon dioxide directly affect the welding process arc power, size and weld metal spatter. To improve the success rate of an arc, requiring the magnetic arc welding process into the current rate of increase of speed and have the best match and control, so as to ensure a high success rate of arc. In addition, to make easier the next arc welding, welding of carbon dioxide are generally located BLT control circuit. BLT is the function of the control circuit wire at the stop when the power supply output voltage down to 12-20V, by the delay and then return to the no-load voltage. Thus, short-arc current decreases when the voltage is reduced, thus avoiding extinction when the Welding Wires ends in the formation of spherical bodies, melting the wire ends into the cone, it is easy to re-arc.

The splash of carbon dioxide caused by the welding process is one of the major hazards spatter adhesion on welding nozzle wall, ensuring that the protection by blocking gas and wire, which had to interrupt the welding process, and to clean up, thus reducing production efficiency. Inverter welding machine of the dynamic characteristics of carbon dioxide regulation is mainly achieved by electronic reactor, thus effectively reduce flying at the same time, easy access to timely adjust the arc and short circuit of the energy distribution, to obtain a good weld.

The reason inverter arc welding power supply with other arc welding, including arc welding power thyristor rectifier do not have unique advantages in the final analysis is due to the introduction of inverter welding power source to run much higher frequency than the frequency of caused by the inverter, so the dynamic characteristics of inverter welding of carbon dioxide and carbon dioxide thyristor controllability is much better than welding, which can greatly improve the success rate of arc, effective control of metal transfer, reduce spatter and improve weld forming. Obviously, the faster the switching frequency IGBT inverter welding power source than the SCR inverter welding power source is more advanced and promising.

With the future chemical tankers and high-speed craft of production increases, Inverter TIG welding application will be developed. Inverter arc welding in the shipyard's potential and promote the use of future development is not, this is because carbon dioxide as a variety of widely used welding process automation and continuous improvement of shipbuilding, the use of arc welding and use of the will be increasingly less load.

According to the East China Shipbuilding Institute, "China Shipbuilding shipyard inverter total arc time application status and prospects of" Task Force in early 1998, the Ministry of the boat 25 shipyards produced variable arc welding machine using the case survey: 25 shipyards have a variety of inverter arc welding machine a total of 321 units. Welding method of classification by: MMAW welder 243 units, 40 units of carbon dioxide welding, TIG welding and 38 units. Inverter arc welding machine according to the use of high-power switching devices Category: SCR inverter arc welding machine 209 sets, IGBT inverter welder with 110 units, GTR and MOSFET inverter arc welding machine each one.

Application of inverter arc welding machine and more effective are: Jiangnan Shipyard, Chongqing Shipyard, Guangzhou Shipyard International Co., Ltd. and other units. Although there are many shipyards in the country have been gradually acquired some of the inverter arc welding machine, but it is in inverter arc welding machine welder in the shipyard share ratio, or the shipyard owned by the inverter arc welding machine against the country's total change the proportion arc welding machine is very low. The shipbuilding welding workers to the reliability of inverter arc welding machine has been a lack of confidence, which is due to "thermal inversion" in 1992-1995 "swept" the country, hundreds of companies in the study of inverter welding machine, and have been developed to varying degrees, different specifications of the prototype or product. Manufacturers compete with each other, the groups of immature laboratory prototype or product to market, "you light weight, I am lighter than you," "you small, I am smaller than you," "You all varieties I am more than you all "," you capacity, I am bigger than you. " But very few manufacturers to its reliability, and maintenance of welding done in-depth research and a solid work. Because a large number of immature products to market, so that our users the reliability of inverter welding machine there is a big concern.

The main reason lies in the manufacture of welding: inverter arc welding machine is a power electronics technology and welding technology, a combination of high-tech products, which is based on power electronics and microelectronics technology development and progress as a guarantee. China's basic industries are relatively weak, in addition to high-power thyristor switching device basically rely on imports, while imports of devices on the parallel market, and therefore it is likely to lead to use the same technology, the same production technology, product quality is very different situations . Many inverter arc welding machine manufacturer means the manufacturing equipment and processes do not meet the requirements of power electronics products, some of the welding machine manufacturers meet the existing plant and equipment inverter arc welding machine production. In addition, some small businesses use manual mode of production workshop production and manufacturing inverter arc welding machine of this high-tech products, it can not effectively control the quality. Of course, there are some technical knowledge of the structure is not reasonable, the lack of deep understanding of the welding power source, some circuit design is also not suitable welding process requirements. Therefore proposed the following approach to solve the problem of inverter welding machine reliability and quality.

â‘´ of immature inverter welding machine is not too early to put into mass production, must be repeated testing, improvement, continuous improvement, quality and reliability in a real solution and then put into mass production.

⑵ main circuit design as reasonable as possible, preferably using computer simulation and CAD, can save debugging inverter design and manufacturing time, and reduce the inverter main circuit components burning. Electronic power devices through the line test instrument, the key device (IGBT fast diodes, etc.) for serious testing, selection and matching.

⑶ dedicated circuit board tester using careful inspection of its parts are working properly, only the advanced facilities of special equipment in order to reduce bias, consistency, and aging of components and complete machine and test experiments.

â‘· maximize production scale in order to use the production line, mold and other advanced means to ensure product consistency and accuracy of the manufacturing process to ensure the quality of each product consistency and reliability.

Third, the gas-shielded welding applications in the shipbuilding industry in the

As the carbon dioxide gas shielded arc welding with a clear, good quality welding, to the all-position welding, soldering, low cost, high efficiency of production, so get to promote, so that gas-shielded welding wire have also been actively developed. As the CO2 Gas Shielded Welding Wire with excellent performance, process performance and good, so common in foreign countries has been applied and fast development. China's carbon dioxide gas shielded welding wire only H08MnSi and H08Mn2SiA and a small amount of solid welding wire (such as ER70S-2 and ER70S-6). Domestic wire problems are more concentrated in the coating, coil, bent hard, joints and uneven areas in diameter. Coating is not good, one poor rust, easy storage; the second is out of copper conductive effects, especially easy to plug the spring tube to increase the wire resistance, and cause arc instability.

    At present, solid wires there are dozens of manufacturers, the shipbuilding industry to be based on nearly 10 years of usage, select the number of stable quality, good performance of the wire manufacturing plant, to enhance the quality of contact and timely feedback and advice on performance improvement, improve the welding quality, in order to better build export vessels. In addition, flux cored wire, domestic production has not yet formed a certain scale, flux-cored shipbuilding industry is still a lot of imports. It is understood that there are other domestic manufacturer to introduce flux-cored wire production line, which greatly accelerated the process of flux cored wire localization.

    Carbon dioxide gas shielded arc welding shipbuilding industry promotion, the main problem is the use of imported carbon dioxide gas protection welding machine, welding wire, its high price, and spend a lot of foreign exchange; and the use of domestic carbon dioxide gas shielded arc welding equipment, welding wire, its quality of instability, it is difficult meet the demand. But this is temporary difficulties, if by the shipbuilding industry and welding materials factory together to continuously improve the quality of wire, to further meet the needs of the construction of the export of ships, will in the shortest period of time up to and beyond the level of imports of flux-cored wire. To this end, we want efficient welding technology in the shipbuilding industry under the leadership of the Steering Group to carry out a planned, step by step made flux-cored wire technology research, the prospects will be made flux-cored wire is excellent.

    IV Conclusion

    As the shipbuilding and efficient welding technology step by step, new equipment, new processes, new materials, widely used, more inverter welding machine and shows the important position of the gas-shielded welding wire. Today, the shipyard is in the process of technological transformation and innovation, the use of inverter welding machine and gradually realize the importance of gas-shielded welding wire.

    But there are still a number of shipyards in the promotion and application concerns, this paper once again to protect the wire manufacturing inverter welding machine and air units should cooperate closely with the needs of shipyard, to seize market opportunities for the shipyard to provide good quality, inexpensive equipment and materials, as a contribution to China's modernization efforts.