At present, electric welding machines are widely used in life, but do you know the principle and characteristics of welding arcs of this electric welding machine? Let's take a look with Chengdu electric welding machine manufacturer Xiaobian:
Inverter DC electric welding machine is a kind of processing equipment that directly or indirectly uses electric energy to heat metal to make it melt or plastically extrude to achieve inter-atomic bonding, thereby realizing welding.
As a basic metal processing method, electric welding is widely used in various sectors of the national economy. About 50% to 60% of the steel output of various countries is generally put into use after being welded into components.
According to the principle of welding heat source, electric welding machine is divided into two basic types: arc welding machine and resistance welding machine. The former realizes welding by melting the joints of the workpiece by the heat generated by the arc, and the latter realizes welding by applying high current to generate resistance heat at the joints of the workpiece to achieve plastic melting and pressurization. These two types of welding machines are the most widely used. With the needs of production and scientific and technological development, welding equipment using other new energy sources or new welding principles (including some equipment that does not directly use electric energy to heat welding workpieces) is increasing.
Generation of welding arc and its characteristics
Welding arc is a strong discharge phenomenon of the gas medium between the two electrodes connected to the power source (the electrode or wire is one pole and the workpiece is the other pole).
Generally, the welding arc is generated by contact isolation. When the two electrodes are in contact and short-circuited, the current density at the contact point is very large, so a large amount of resistance heat is generated, which causes the temperature to rise, and the electrons on the cathode surface can escape and cause thermal reflection; at the same time, the metal is melted and evaporated , Cause quite strong heat release. Then, pull the electrode apart. Under the action of no-load voltage, when the electrode is just pulled apart for a short distance (for example, 1 × 10-7 ～ 1 × 10-6cm), a considerable electric field strength is established between the electrodes, so that the electrons on the surface of the cathode escape. Generates white emission. The electrons released by thermal emission and white emission move at high speed under the action of the electric field of the electrode and violently strike other neutral atoms in the gas medium to cause ionization. At the same time, light and heat are generated. When the degree of ionization increases rapidly, that is, Formation of a stable electrically isolated discharge. This process is collectively known as sparking or arc starting.
For a welding arc of any length, when the current flowing through it is a stable value, the relationship between the arc current and the arc voltage is called the static characteristic of the welding arc (for AC arcs, the arc current and the arc voltage are both valid values Means).