Welding Methods

1. The arc temperature of argon arc welding is generally between that of plasma arc welding and manual arc welding, ranging from 9,000-10,000 K. The arc temperature for plasma arc welding is 16,000-32,000 K, that for manual arc welding is 5,000-6,000 K, that for consumable electrode argon arc welding is 10,000-14,000 K, and that for oxyacetylene flame is 3,100-3,200 K. The main risks are respiratory and lung infections caused by welding dust; myopia caused by the arc light; and hearing loss caused by the noise.

2. In electric welding, the workpiece and electrode are connected to different poles (positive or negative) of the power source. The electrode and workpiece come into instantaneous contact, ionizing the air and generating an arc. The arc reaches a very high temperature, approximately 5,000-6,000 K, melting the workpiece surface to form a molten pool. The molten metal in the electrode is then applied to the workpiece surface, forming a metallurgical bond.

3. "Oxyacetylene flame" refers to the flame of acetylene (commonly known as calcium carbide gas, produced by the reaction of calcium carbide and water) burning in oxygen. The reaction is expressed as: acetylene + oxygen, carbon dioxide + water.

This reaction releases a large amount of heat, causing the flame temperature to reach over 3000°C. Steel quickly melts upon contact with the flame. Taking advantage of this property, oxyacetylene flames are often used in production for welding or cutting metals, commonly referred to as gas welding and gas cutting.

Gas welding uses the high temperature of an oxyacetylene flame to fuse two pieces of metal together. The key is to prevent the metals from being oxidized by the oxygen in the air at high temperatures. To achieve this, the amount of oxygen used must be controlled to prevent the acetylene from burning completely.

This flame, due to the carbon monoxide and hydrogen produced by the incomplete combustion of the acetylene, has reducing properties.

This flame prevents the metal parts and welding rod from oxidizing and changing their composition during welding, and prevents the weld from being stained by oxides...

4. Water welding should be a welding technique used under special conditions.

5. The temperature of the oxyhydrogen flame can reach 2500-3000°C. Even quartz, which has a very high melting point (1715°C), can be melted by the oxyhydrogen flame. Therefore, the oxyhydrogen flame can be used to process quartz products.

The C₂H₂ flame and the H₂O₂ flame have different applications. The oxygen in the H₂O₂ flame is highly oxidizing, and in some cases, the H₂O flame is not used to prevent metal oxidation during welding.

In contrast, the -1 carbon in C₂H₂ has reducing properties. Using a C₂H₂ flame not only allows for welding metals, but also allows C₂H₂ to be used as a shielding gas to prevent oxygen in the air from oxidizing the metal being welded and the welding rod. Commonly used welding machines include the E43 and E50 series. Conventional electric welding machines operate on a similar principle to a transformer, a step-down transformer.

The workpiece and welding rod are located at either end of the teeth and coil. The arc is ignited, and the high temperature of the arc fuses the gap between the workpiece and the welding rod. Welding transformers have a unique characteristic: a sharp drop in voltage.

The voltage drops after the welding rod is ignited; the voltage also drops sharply when the welding rod becomes stuck and short-circuited. This phenomenon is caused by the characteristics of the welding transformer's iron core.

In addition to the primary 220/380 voltage conversion, the secondary coil also has a tapped voltage adjustment, and this is also adjusted using the iron core. The amount of iron entering the adjustable core shuns the magnetic circuit; the more iron entering, the lower the welding voltage.