Arc welding

The energy of the arc (heat and light) is concentrated and is used to melt the metal when soldered.

Arc is a strong and continuous discharge in the gas between the opposing electrodes. In order for the discharge to occur, the gas must conduct electricity (containing charged particles such as ion, free electrons). The condition for generating charged particles is in the space between two electrodes, including:

   ☀ Electronic thermal emission

   ☀ Photovoltaic emission

   ☀ self-emission

   ☀ Shock emission or ionization of volume.

This means creating a voltage, called an ionizing potential, that pulls electrons out of atoms or molecules, converting them into ions. In fact, arc welding contains both metal and vapor.

By introducing a small amount of low ionic voltages into the medium (for example, potassium compounds), the effective ionization potential of the gas mixture in the arc decreases sharply, making The arc is more stable.

Welding arc formation
The welding arc formation can be divided into 4 stages, drawing

State 1

Because the top surface of the welding rod and the welding set price is not completely flat, when the welding rod is in contact with the welding object, a short circuit (concentration of electric current) occurs in the place where the electrical contacts are exposed, producing a large amount of heat. In very short time.

Phase 2

The metal flows rapidly at the contact surface and fills the space between the electrode and the weld.

Phase 3

When the electrode is picked up, the magnetic field acts on the molten metal column, its cross section decreases, resulting in increased current density (Pinch effect).

Stage 4

Liquid metal rapidly boils and evaporates, the metal column is broken, resulting in arc formation.

When the arc welding forms the electronic surface of the cathode and the voltage increases significantly, resulting in increased general emission. The electrical conductivity of the arc also increases until the current increases and the voltage decreases to a certain value, creating the arc’s stability.

Arc space can be divided into 3 regions

☀ Anode region (positive).

☀ Catodal region (cathode).

☀ Arc pole area. => The arc is maintained through the emission of electrons from the cathode.

The post Arc welding appeared first on Máy nông ngư nghiệp.