Taking into account earlier carried investigations, considered are the issues of development of the electron devices for contactless initial and repeated ignitions of alternating current arc in mechanized arc welding. They generate high and increased voltage pulses being injected in an inter-electrode gap. It is shown that the most reasonable way for improvement of the electron devices is a development of combined striker-stabilizers. They have a possibility to function in a mode of initial

more »

... tion (striking) of the arc as well as in a mode of its burning stabilizing. It can be reached by means of using at least two independent forming circuits in the generators of high or increased voltage pulses of the striker-stabilizers. A variant of circuit solutions for the combined electron arc striker-stabilizer having series connection to welding circuit is presented and described for mechanized consumable electrode AC welding. 22 Ref., 2 Figures. K e y w o r d s : mechanized arc welding, alternating current, initial and repeated arc ignitions, arc stability, electron striker-stabilizers of arc, generators of high and increased voltage pulses Up to the moment the most widespread method of contactless initial ignition (striking) of welding or pilot arc in an inter-electrode gap is its impact ionization by means of electric breakdown of this gap by high-voltage pulses, being generated with the help of special generators (arc strikers) [1] [2] [3] [4] [5] [6] [7] . The methods based on application of increase voltage pulses have gained the widest application among the well-known methods for increase of AC welding arc stability. Such pulses are generated by special voltage boosters (arc stabilizers) and being fed in the inter-electrode gap once in a period (at the moments of beginning of cathode formation on a part) or at each change of welding current polarity. Also different methods which provide for high speed of change of arc voltage and current at current zero values are used [1] [2] [3] [4] [5] [7] [8] [9] [10] [11] [12]. Regardless the fact that a nature of processes of initial and repeated welding arc ignition is different [3-5, 7, 9, 10], a design structures of special strikers and stabilizers of arc is the same. Along with, due to the process peculiarities which are realized by these devices, they differ from each other not only by amplitude, energy and time parameters of the output pulses, but algorithms and modes of control assemblies. In this connection, the design of striker-stabilizers in course of long time was realized via combination in a one block virtually two independent devices. One of the devices is functioning in a mode of initial ig-nition and being controlled by open-circuit voltage of AC power source. The second one operates in a mode of arc reignition in welding with arc voltage regulation. The examples of such a solution can serve the arc striking and stabilizing blocks of UDG-301 and UDG-501 units for TIG welding of aluminum and its alloys, UDGU-301, UDGU-302 and UDGU-502 units for TIG welding of steels and non-ferrous metals [5]. Based on mentioned above, the researchers and developers in a course of long time have been trying to develop the combined electron arc striker-stabilizers which can effectively function in a mode of arc initial ignition as well as in a mode of its reignition. A series of such devices [5, 7, [13] [14] [15] [16] [17] [18] [19] as an example], was developed up to the moment, however, area of their application is limited by such arc welding methods as manual and automatic non-consumable welding in inert gases (TIG) and manual metal arc welding (MMA). A number of difficulties and limitations in application [9, 10, 20] were found in development of the combined electron arc striker-stabilizers for mechanized AC metal arc welding in shielding gas (MIG/MAG). Therefore, the development of efficient striker-stabilizers of arc for MIG/MAG welding is still relevant tasks. The analysis of circuit design and structural peculiarities of known combined electron arc striker-stabilizers shows that the solution of this problem is possible under conditions of improvement of operation algorithms of these devices and their control