Systems to Control Molten Metal Transfer in Arc Welding

Abstract

Abstract. The paper analyzes the systems used for controlling molten wire metal droplets during the arc welding process in shielding gases. The variations for implementing the relevant systems are given, with the positive and negative aspects of such implementation taken into account. Electrical systems are currently investigated to the fullest extent possible and implemented in different power sources for pulsed welding arc. Mechanical systems are represented by different types of feeders that provide the pulsed wire feeding process. The feed mechanisms driven by electric motors and electromagnets are analyzed. In addition to the mechanical and electrical systems, the examples of combined control systems are given. IntroductionMechanized and automatic consumable electrode arc welding is the basic technology to have a permanent joint. Gas-shielded metal arc welding is the most widely used in industries over the world.The developed and offered on the market consumable electrode welding techniques are constantly improved with the purpose to obtain joints having an optimal balance between geometry and metal quality, reduce the costs of further processing works, and reduce the consumption of material and energy resources. A number of features pertaining to the gas-shielded welding process depend on a type of electrode metal transfer.The transfer of wire electrode metal to a weld pool can normally be divided into three main stages. During the first stage a droplet of a specified size is formed at the electrode tip. Within the second stage the droplet's growth stops, and this droplet together with the electrode contact tip approaches to the weld pool. The third stage completes with the metal transfer to the pool when the bridge between the electrode tip and molten metal drop is destroyed.There are several variations of metal transfer in the AW process using gas shields; the basic types are featured as follows: with naturally occurring short circuits;  with continuous arcing and droplets or globs of metal transfer;  with continuous arcing and spray or rotating spray transfer of metal. The types of metal transfer as well as forces acting on a wire electrode metal while arcing are described in [1,2]. Each type of metal transfer has both advantages and disadvantages.