Current high-energy beam welding are major areas of concern are: ① the large-scale high-energy beam equipment - large-scale power and can process parts (even parts integration) of the large-scale. ② the development of new equipment, such as the pulse work and short-wavelength lasers. ③ processing equipment, intelligent and flexible. ④ beam to improve the quality and diagnosis. ⑤ beam, the workpiece, the interaction mechanism of the process medium. ⑥ composite beam. ⑦ new welding. ⑧ applications expand.

The latest developments in laser welding

A new type of laser
(1) strip-type DC (DC Slab) CO2 laser, (2) diode-pumped YAG laser, (3) CO laser, (4) Semiconductor lasers, (5) excimer lasers.

2 large-scale laser power, beam quality and pulse mode
PRC's case to the United States a few years ago, the CO2 laser for cutting the main power is 1500 ~ 2000W, and the recent leading product is 4000 ~ 6000W, 6000W stainless steel can be cut thick, steel thickness of 35mm and 40mm.

3 equipment, intelligent and flexible processing
Especially for the YAG laser, optical fiber transmission as available, to the process brought great convenience.
Its main features are: ① a machine. ② using a laser machine can be multi-bit (up to 6) processing. ③ fiber length up to 60m. ④ open the control interface. ⑤ with remote diagnostic capabilities.

4 composite beam
The main laser - arc complex. Deep penetration Welding Electrode, plasma is produced above the pool, composite processing, laser-produced plasma is conducive to the stability of the arc; complex processing to increase processing efficiency; can improve poor welding materials such as aluminum, dual-phase steel welding sex; increase the stability and reliability of welding; Typically, laser welding is very sensitive Holes, combined with the arc, then becomes easy and reliable.
Laser - laser and arc complex is mainly TIG, Plasma and GMA. Through the interaction of laser and arc, each method can overcome its own deficiencies and, thus, a good composite effect.
GMA low cost, the use of filler wire, applicability, drawback is that the depth of melting, welding speed is low, the workpiece to withstand large heat loads. Laser welding to form deep and narrow weld, high welding speed, heat input is low, but high investment, high precision preparation of the workpiece, for aluminum and other materials, poor adaptability. Laser-GMA composite effect in: arc added to the bridging of the gap, for two reasons: First, the filler wire, the second is a wider range of arc heating; arc power decide the width of the weld at the top; laser-produced plasma body reduces the arc ignition and maintenance of resistance to a more stable arc; laser power determines the weld depth;
From the energy point of view, laser arc hybrid welding efficiency is very significant. This is mainly based on two effects, first, a high energy density resulted in higher welding speed; Second, the combined effects of interaction between two heat sources.
GMA, Laser Holes and laser arc hybrid Aluminium Welding Electrode line of three methods of energy, and energy efficiency of the weld cross-section comparison.

Description: underwater welding underwater welding and cutting underwater engineering structures, installation, maintenance, construction of an important and indispensable means of technology. They are often used in marine salvage, ocean energy, ocean mining, marine engineering and construction of large water facilities of the process.
Underwater welding
Underwater welding are dry, wet, and local dry three.
(A) dry welding
This is a large chamber covering the use of welding parts, welder welding in a gas chamber method, because it is in the dry gas in Welding Electrodes, its security is better. Dive deeper than the air in the range, the air environment due to increased oxygen partial pressure, prone to Mars. Should be used in the gas chamber or semi-inert inert gas. Dry welding, welders should wear a special fire protection, high temperature protective clothing.
With wet and dry welding compared to the local, the best dry welding safety, but they use very restrictive and the application is not widespread.
(B) local dry welding
Local dry welding is welding in the water, but the artificially drained around the welding area to open the underwater welding method, similar to its security measures and wet.
As the local dry is still in the study, so use is not widespread. . 320 -
(C) wet welding
Underwater wet welding is the direct welding welder, welding instead of artificially drained areas around the open method of underwater welding.
Submerged arc similar to underwater burning and is burning in the bubbles. Burning welding electrode coating on the sleeve so that the formation of stable bubbles exist, thereby stabilizing the arc, as shown in Figure 8-1. For stable combustion of underwater welding, electrode core must be coated with a layer of certain thickness on the applicator and wax or other waterproof material with the impregnation method, the electrode water-resistant. Bubbles of hydrogen, oxygen, water vapor and combustion by the skin electrodes drug bubbles; muddy oxide fumes and other students. To overcome the water
Cooling and pressure caused by the arc and arc stability problems, the arc voltage is higher than the atmosphere of the arc voltage, the current large larger gas welding current 15% to 20%.
Wet and dry underwater welding and welding compared to the local dry, the most widely used, but security is the worst. Since water has a conductivity, so the wet welding electric shock as the main security problem wait one.
Underwater welding and cutting of the cause of the accident
Underwater welding and cutting-induced risk factors is characterized by: arc or gas flame underwater use, with welding or in the atmosphere compared to normal diving operations, with greater risk.
Underwater welding and cutting operations common accidents are: electric shock, explosion, burns, burns, drowning, crushing, diving disease or suffocation injuries. Cause of the accident the following points:
(1> to sink to the ship or other underwater objects often ammunition, fuel containers and hazardous chemicals, welding and cutting operations before the rash did not identify the situation in the welding and cutting process will explode.
(2) The tempering and hot metal droplet burns, operator, or burned for trachea, diving suits and other diving gear with the accident.
(3) due to insulation damage or improper operation caused by electric shock.
(4) collapse occurred underwater structures injured, crushed, crushing and even fatalities.
(5) As for the trachea, diving suit burn, electric shock or drowning accidents caused by sea waves.
Underwater welding and cutting safety measures
(A) preparation
Underwater welding and cutting safety is an important feature: a large, multifaceted preparation, generally include the following aspects:
(1) Survey work area weather, water depth, water temperature, flow and other environmental conditions. When the surface wind is less than 6, the operating point of the flow velocity is less than 0. 1 ^} 0. 3m / s, when, before the operation.
(2) Underwater Welding Welding parts to be identified before the nature and structural characteristics of the job object to ascertain whether there is within the flammable, explosive and toxic substances. That may fall, collapse due to fixed objects, especially underwater cutting should pay special attention to prevent crushing or damage for the trachea and cables.
<3) before the dive, in water, deal with welding and cutting equipment and tools, with diving equipment for pipe and cable, communications tools such as insulation, watertight, check the performance of test process. Oxygen hose to use 1.5 times the working pressure of the steam or hot water, inside and outside hose shall adhere to grease. Trachea and the cable should be securely tied at intervals of .5 m, so as to avoid neck and neck with each other. Dive into the water, it should be collated in time for the pipe, cable and signal wire, make it in a safe location to avoid damage.
(4) above the operating point, the radius of the equivalent depth of the area, not at the same time other operations. For underwater operation will not burn gas or toxic gas escape and float to the surface, water fire personnel should prepare measures for the pump and should be placed upwind to prevent fire or inhalation of toxic gases underwater personnel poisoning.
(5) before the operation, the operator should work sites safe handling, removal of surrounding obstacles. Underwater welding and cutting operations shall not be suspended in the water, should be pre-installed operating platform, or on the object selected safe operating position, to avoid their own, with diving equipment for pipe and cable in the slag splash or flow range.
(6) and surface support divers welding and cutting staff to have communication among devices, when all preparations, support staff in obtaining consent, Aluminium Welding Electrode and cutting staff before beginning work.
(7) engage in underwater welding and cutting operations must go through specialized training and work permit holders of such personnel.