Abstract
The essence and complicacy of approach to computer design of an optimal pulsed arc welding technology is that programmed periodic action should be developed on the one hand to exert its effect on melting and transfer of an electrode metal, and on the other hand, to control over the molten pool fluidity, the structural formation of weld and heat-affected zone (HAZ) that appears as result of the weld pool crystallization whilst ensuring stability of the pulsed regime in welding in different spatial positions. The results of physical simulation and mathematical modelling permit to design optimal algorithms of pulsed control of energy parameters of welding arc current and voltage, arc heated efficiency, peak short-circuiting current. The results of computer experiments permit to establish pulsed welding controlled parameters service properties of welded joints (such as the sizes of welds and HAZ, quality and strength properties of welded joints) relation. The solution of the pulsed arc welding and surfacing processes optimizing problem is a matter of great significance because of continuously increasing requirements on quality and reliability of welded joints, saving in welding fabrication cost. The construction of welded structures has a number of special features. These are associated with the character of welding metallurgy and solidification processes in the weld metal, the welded joint heating and cooling conditions and others, influenced on the stability of parameters of the complex electrodynamics’ system: “power source – electrode – arc – weld pool – welded joint”. It is necessary to ensure the regulation of the penetration depth, welding in wider gaps and in different spatial positions, joining metals and alloys of dissimilar chemical composition, decreasing the degree of splashing of electrode metal, increasing the stability of arc ignition and arcing. Arc heating sources energy concentration is unable to solve these technological problems including increasing the productivity of welding operations and improving the welded joints quality parameters. The rate of assembling operations in the construction of pipelines is increased mainly as a result of automation of welding non-rotating joints. The main part of the system of transmission pipelines in Russia for the transport of natural gas, oil and products of processing mainly of the high-pressure type and with a large diameter (1220-1420 mm) has been operating for a relatively long period of time: 30% of gas pipelines have been operating for more than 20 years and 15% for more than approximately 30 years. In order to maintain
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