In recent years, with the rapid development of the national economy,
China's heavy machinery metal structure manufacturing has made
remarkable achievements.
China is not only a world's largest steel consumer, but also a world
machinery manufacturing power. According to the International Iron and
Steel Institute (IISI), in 2004 the world's steel output reached 1.03
billion tons for the first time, and the amount of steel used was 935
million tons. China's steel output in 2004 was 272 million tons,
accounting for 26% of global steel production. The annual steel
consumption was 312 million tons, accounting for 33% of global steel
production, of which 160 million tons were used in welded structures,
accounting for steel. About 51% of the amount. In Europe and the United
States and the former Soviet Union, steel for welded structures accounts
for about 60% of its steel use, and Japan has more than 70%. This shows
that we still have a certain gap compared with industrial developed
countries. According to relevant investigations, in the 160 million tons
of welded structural steel, the steel used in the metal structure of
the machinery manufacturing industry accounts for about 45% of the steel
volume. The rapid development of the steel industry gives the welding
industry in China, especially the heavy machinery metal structure
industry. The sustainable development of technology has created a lot of
room for development. Entering the 21st century, China's heavy
machinery industry is facing new challenges and opportunities. It should
thoroughly improve the traditional welding industry with large energy
consumption, high consumables, low efficiency, poor working environment
and low automation, and promote the welding technology and industry to
high quality and high efficiency. Energy-saving, low-cost,
environmentally friendly and automation development, and strive to
transform the relative advantages of human resources into technological
competitive advantages, and promote enterprise progress and industrial
upgrading.
Industry welding technology status
1. Overview of domestic and foreign
Welding technology is one of the key process technologies for the
manufacture and installation of heavy machinery metal structure
equipment. It is widely used in heavy machinery manufacturing industry
in industrialized countries. Up to now, China's heavy machinery welding
technology has developed in the United States (such as P&H, etc.),
Germany (such as SMS, etc.), France (such as voestal, etc.), and Japan
(such as Mitsubishi Heavy Industries, Komatsu, etc.). There is a big gap
between countries. At present, the proportion of welded structural
parts in these countries and regions is increasing. The welding metal
materials consumed by high-efficiency welding methods such as automated
and mechanized gas shielded welding and multi-filament submerged arc
welding account for about 50% of the total amount of welding
consumables. 70%, its welding production adopts mechanized, automatic
and efficient welding process, which brings high welding production
efficiency and good welding quality, and has strong international
competitiveness.
In China's heavy machinery metal structure
industry, gas-shielded welding, double-wire submerged arc automatic
welding, gantry welding machine, electroslag welding and other
high-efficiency welding methods are increasingly used in large-scale
metal structure manufacturing enterprises, and metal structures
completed by high-efficiency welding methods The parts have accounted
for 50~80% of the total weight. In small and medium-sized enterprises,
CO2 gas shielded solid wire and submerged arc automatic welding have
also been applied. But overall, the advantage of low labor wages in
China's heavy machinery manufacturing is being offset by the huge gap
between low production efficiency and high quality costs, which should
cause us to pay enough attention.
2. Product situation
The heavy machinery metal structure industry mainly provides heavy machinery and equipment for large-scale national backbone enterprises and national key projects.
3. Heavy duty machinery metal structure industry steel
For a long
time, China's heavy machinery metal structure industry mostly uses
mature steels at home and abroad, such as Q235 series carbon steel,
Q345, Q390 series low alloy steel, 20g, 16MnR pressure vessel steel. In
recent years, with the development of national key projects and the
adjustment of product structure, the types of steel for welding have
been greatly improved.
4. Welding process
The heavy machinery metal structure industry
began to use the manual arc welding process. In the 1950s, the submerged
arc automatic welding and electroslag welding process were used, which
were mainly used for some thick plate butt joints, work beam and barrel
welding. In recent years, some large enterprises have successively
applied advanced welding methods such as double wire submerged arc
welding, double wire narrow gap submerged arc automatic welding, gantry
type welding machine and roller submerged arc surfacing through
technical transformation to meet product manufacturing technical
requirements. .
