Solving the problems of underwater mecha-nized and automatic arc welding of various metal structures with a wet method

A complex of problems related to semi-automatic and automatic underwater wet welding, concerning both equipment and ways of implementation of arc process, has been considered. An analysis of existing developments in the considered field of welding has been carried out, and the most rational designs of semi-automatic machines for welding with flux-cored electrode wire have been revealed. It is shown that the semiautomatic device with a submerged block is the most rational design; the feeding mechanism, placed in the block, has its own additional body, filled with insulating-lubricating liquid, in which the drive motor is submerged. It is noted that a peculiarity of welding-in-fusion in aqueous medium is unpleasant formation of joints on the vertical plane. The most effective ways of improving semi-automatic and automatic machines related to modulated processes and processes with controlled pulse feeding of electrode wire are presented. It is shown that lately the most effective choice of electric motor is its valve design. At the same time, the feeding mechanism in the gearless version is possible. Specially designed computerized control and regulation system is used for realization of semiautomatic machine's work cycle and the chosen algorithm of electrode wire feeding. The results of electrode wire pulse feeding application on properties of welded joints are given. It is determined that characteristics of pulse feeding (frequency, duty cycle) influence geometric characteristics of the weld, as well as strength properties, in particular yield and time resistance limits, which, among other things, is caused by reduction of nonmetallic inclusions in the weld metal and the weld zone. External types of beads welded in aqueous medium on the vertical plane are given, it is obvious that formation when using pulse and modulated modes is significantly better than when conducting electric arc process with conventional feeding of the electrode wire. The ways of further improvement of the equipment for welding in aqueous medium by a wet method are shown. One of the most promising ways to improve technical and technological capabilities of mechanized equipment for welding in aqueous medium is the creation and application of systems with combined influence on the process.