Miniature open type device with adjustable air gap for underwater local dry method welding and welding method

Abstract

The invention discloses an air-gap-adjustable miniature open type device for an underwater local dry method and a welding method. The structural design of the open type device is based on the fluid mechanics theory. Comprising a coaxial air supply and wire feeding device, a conducting rod, an outwards-convex curve-shaped outer wall contour and a welding gun nozzle with the bottom shrunk, and further comprises a welding gun body connected with a middle layer and an outer side drainage cover air path, a middle layer drainage cover with an inverted cone frustum outer wall contour with an angle, and an outer side drainage cover with an inverted cone frustum cavity contour with a certain angle. According to the open type device, the middle layer drainage cover and the outer wall of the welding gun are matched to form an ultra-narrow gap air gap within the range of 0-2 mm, and the outer side drainage cover of the open type device and the outer wall of the middle layer drainage cover are matched to form an ultra-narrow gap air gap within the range of 0-2 mm; according to the open type device, high-precision adjustability of air gaps of the middle-layer drainage cover and the outer-side drainage cover can be achieved, and the range is 0-5 mm; according to the open type device for underwater local dry method welding and the welding method, the working distance between the open type device and the to-be-welded workpiece is 30 mm or above, the open type device is not closed, the better local dry environment can be kept under the basic requirement for underwater all-position welding of the uneven workpiece is met, the dry area radius of 40 mm or above is formed, the size is small, the weight is light, the manufacturing cost is low, and the application range is wide. And the engineering application range is wide.

Description

technical field [0001] The invention relates to the field of welding, in particular to a micro open device with adjustable air gap for underwater partial dry welding and a welding method. Background technique [0002] Underwater welding has been widely used to manufacture and maintain offshore engineering structures such as pipelines and nuclear power plants. In recent years, the rapid development of the marine industry has further promoted the application of underwater welding technology. Underwater welding is generally divided into dry welding, wet welding and local dry welding. Common problems encountered in wet welding are that under the action of surrounding water, the weld forming ability is poor, the cooling rate is fast, and pores and cracks are formed inside the weld, which limits the quality of the welded joint. Both local dry welding and dry welding eliminate the adverse effects of the water environment. In dry welding, the workpiece and welding equipment are pl...

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Problems solved by technology

[0003] Underwater local dry welding relies on the design of drainage devices. The difficulty lies in draining the water in the welding area and forming a stable dry environment. At the same time, the fixed internal structure design of the drainage cover is also difficult to achieve complete drainage under different drainage capacity requirements. Adaptability limits its scope of application; at present, scholars have designed air chamber type and dry point type drainage covers with gas as the drainage medium based on the idea of ​​forming a good mechanical closed space between the drainage cover and the workpiece to be welded. Due to the small working distance and the tightness of the space, there are still some deficiencies in the local dry welding process: (1) The drainage gas enters the partially sealed welding area and easily forms a high-pressure wind field, which affects the arc stability and weld formation; ( 2) The direct contact between the drainage cover and the workpiece to be welded and the mechanical seal result in poor mobility of the device, and insufficient welding flexibility and applicability; (3) For the uneven surface of the workpiece to be welded, the small working distance increases The difficulty of welding affects the stability of the welding process; (4) The working water depth in the actual working conditions of underwater welding is different, and these different welding environments have different requirements on the degree of dryness. It is difficult for a single type of drainage cover to meet all working conditions, so The adjustability of the drainage gas is also particularly important

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