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.

Welding application problems encountered
Carbon steel wire, a single species

China CO2 carbon steel wire only ER49-1 and ER50-6 two varieties, a single CO2 gas welding, there is more than splash, raised bead molding and other shortcomings, we bear the fatigue loads weld metal structure or appearance of the cooperation of high quality welding products, most use of argon-rich gas mixture. Generally only use ER50-6CO2 wire, while the United States and Japan YGW15 ER70S-2 wire, with the exception of sulfur, silicon content is low, but also added zirconium, titanium and lead deoxidizer, welding on the surface of stainless steel, impurities less sensitive, so in argon-rich gas mixture used welding wire ER70S-2 and YGW15 more appropriate.

2 high-strength steel, heat-resistant steel Welding Wires Manufacturer less

In recent years, with the adjustment of product structure, welding metal materials ranging from common Q235, Q345 to high-strength steel (such as the Wel-ten80C), high toughness steel, heat-resistant steel (such as 21CrMo10) and other areas, but China which rare class wire manufacturers, are often long lead times, high prices, can not meet production requirements. Some special steel wire is still dependent on imports. In actual production, steel welding for more, only to change the selection of imported wire or welding processes.

2.1 wire structure is irrational

Foreign elements in low-carbon steel wire Mn wire limit is equivalent to ER49-1, wire drawing, welding and mechanical properties are better than ER49-1 wire. Due to the impact of raw materials and traditional values, the current number of users is still mainly ER49-1 wire, the wire is the imitation of the former Soviet Union, chemical composition unreasonable, Mn element content higher, not only in the low-carbon steel welding wire waste, And Roberts will bring difficulties to increase the annealing process, based on years of testing and practice, ER50S-6 welding wire stable, spatter, weld appearance, strength of deposited metal wire and ER49-1 equivalent, but its plasticity, toughness than ER49-1 wire. Therefore, the welding mild steel, should be preferred ER50S-6 welding wire, CO2 welding wire to make our structure more reasonable.

3 CO2 welding wire welding performance

Through these years of research and application of welding wire at home and abroad, we are the mechanical properties of wire made despite poor than similar foreign wire, but can basically meet the requirements, and welding process performance problems are more prominent, to a certain extent, restricted the CO2 Gas Shielded Welding Wire development. Present in the stiffness of domestic wire, wire stability, spatter, weld, and other aspects of the applicability of a certain gap between foreign wire, welding production can not meet the requirements of the development.

4 wire tensile strength, from Alice

4.1 The tensile strength of wire

Usually by wire to measure the tensile strength of wire hardness, type of push wire feeder wire, the wire is a measure of the hardness of the important process performance indicators. Wire hardness and chemical composition, the drawing process. At present, the welding wire manufacturers and users generally only paid attention to wire the physical and chemical properties, ignoring the tensile strength indicators, through testing and practice, we believe that hard-wire some of the more well-made, therefore, our standard φ1.2mm carbon steel wire wire tensile strength of 1000 ~ 1200MPa, the basic guarantee of the stability of the wire (such as Kam Tai, Monkey King, Atlantic, China through companies such as wire).

Alice from the wire of 4.2

Alice from the wire to the wire has a certain influence, Alice from the large, wire tube with guide wire friction, increasing wire resistance, with the production of straightening the wire, our use of foreign wire (φ1.2 ) Alice from generally less than 5mm, Japan KC-50 wire from the zero of Alice: Alice from the wire and made much smaller than 5mm, which should attract enough attention of manufacturers. Based on the above, our company standard wire should be less than 10mm from the following Alice.

The quality of copper wire 5

Copper wire currently used plating and electroplating of two ways. Plating, low cost, small porosity, coating with low intensity, high cost of plating, porosity, coating with high strength. Plated wire commonly used in Japan, Western Europe, the use of electroless plating, chemical plating our places, but a few manufacturers to adopt plating.

5.1 non-uniform copper layer, combined with weak, easily out of copper scrap

Metallographic microscope in Japan KC-50 wire, found more uniform coating, no copper accumulation phenomenon, the pinhole was smaller, dense coating. The relatively poor domestic wire, welding wire through the wire wheel off copper scrap, severe loss of large, wire tube blockage, workers often had the guide wire tube with compressed air to remove copper scrap.

5.2 copper layer rust easily, saving time is short

Domestic wire corrosion is mainly matrix interface with the copper layer rust. Some just sent to the factory wire, found rust on the surface, kept for some time and found some rust, can save almost half of the wire is small, and Japan, Germany wire can be stored more than three years, showing the quality of domestic copper wire to be further to improve.

Quality copper wire has been restricting the development of China's gas-shielded welding wire and application. Therefore, it is necessary to develop a reasonable process specifications; second is to strengthen the pre-plating process to improve the ability of rust to fat; third is to solve the copper agents, lubricants, brightener, the quality of drawing dies. Easy to clean, such as foreign lubricants, rust, welding spatter, drawing mode for the rotary, pull the surface to avoid wire marks, reducing the wire of the ellipse.

Copper wire is the application of non-nano-technology and modern colloidal intermetallic compound coating technology, a new type of wire surface layer treatment, compared with the traditional copper wire, with a stable arc, low spatter, forming beautiful, rust-proof ability , smoke toxicity and pollution, and low cost. In Japan, the United States and other industrialized countries have been rapidly replacing copper wire of the situation, China Kam Tai, three British, the Monkey King and other companies have developed the production of such wire. In 2003 the company began to promote the use of non-copper wire, to achieve a certain effect, but the welding quality is not very stable, mainly for the poor conductivity, wire less stable, conductive mouth, badly worn, etc., in the future need to continue research and development , to master the non-copper wire manufacturing technology, improve product quality to meet the actual production requirements.

7 Packaging Wire

Foreign wire is plastic packaging, and placed in moisture-proof silicone agent class, attractive and durable packaging, wire a general one ton wooden crates, easy storage, handling, requisitioned. Domestic wire for packaging, often occurs to absorb moisture, scattered disk, wire tray, box damaged and are not allowed and so on (Kam Tai, the Atlantic, the Monkey King and other welding wire packaged good companies). Therefore, the welding wire packaging can not be ignored.

8 wire technology standards

And revision of the standard wire for gas shielded solid wires is essential to further promote the use of, our wire standard, most current standards with the United States for the equivalent, due to financial and other reasons, the standard revision cycle length, part of the standard still lags behind in foreign standards, the development of production can not meet the requirements in the actual production, we can only refer to relevant foreign standards, wire selection, testing and product acceptance. Therefore, we hope to step up international standards of our wire standard revision.

9 production of macro-control wire

Gas-shielded welding wire is technology-intensive products, to ensure that welding wire feed hose from the normal send, wire quality play a key role. A few years ago, the domestic metal products industry, wire rope plant, township and village enterprises believe that CO2 welding process is simple, the market demand, the blind on the production line, welding wire plant development to more than 150, according to statistics, there are only 16 in Jiangsu Province, 13 Hebei Province, Shanxi Province, such as energy and heavy chemical industry base, though built with a wire factory, and have not the product. As the quality of welding wire plant and irrational volatility, production often not timely delivery and return issues. For the above, our company developed a TZL911-2000 "commonly used in gas shielded arc welding of carbon steel wire" standard, and take a sub-supplier qualification assessment methods to ensure welding quality and production cycle.

10 protective gas

A few years ago, still no welding with shielding gas, plant, were collected in the form of by-products (if any lime pit, ethanol plant, chemical industry, etc.), so the higher the gas impurities, mainly water and sulfide, the reach the welding gas purity standards. At present, only two manufacturers of professional gas joint venture, Praxair and BOC gases that companies can offer a variety of CO2 and argon-rich gas welding, and high purity gas, to meet the product requirements, but still there is no timely delivery, affecting the production cycle, high gas prices, increased production costs and other issues.