6 – laboratory work studying the structure of gas welding technological process and devices

6 – LABORATORY WORK


Studying the structure of gas welding technological process and devices 1. Purpose of work
1) study of welding technology, techniques and equipment.
2) perform simple welding work in a m al.
2. General concept of gas welding khaki.
In gas welding, heating and liquefaction of metals is performed on the basis of heat energy released by combustion of combustible gases in oxygen. (Figure 1).
This method has advantages such as its simplicity and the fact that it does not require expensive equipment. The welder is very important in obtaining quality welds. In practice, gas welding is widely used in the welding of thin steel, non-ferrous metal alloys, cast iron, in the preparation of reservoirs, dishes, and in the repair of various defects (pains, cracks).

Scheme.
Figure 1. Gas welding scheme.

1 – burner;

2 – flame;
3 - welding van a si;
4 – п weld seam;
5 – the base is metal;
6 – chokbop sim ;

3. Abrasive materials for gas welding.
3.1 Oxygen Oxygen in the form of a 99.5% purification gas is used for welding. Oxygen is tasteless and does not burn on its own, but increases the power of the flame. Oxygen is obtained by liquefaction of air. Oxygen is stored in compressed form in cylinders or in liquid form in transport tanks.
3.2 Combustible gases. Acetylene or a mixture of carbon (coke gas, natural, technical propane, etc.) can be used as a combustible gas. Liquid fuel (gasoline, kerosene, benzene) can be used.
Sa S ₂ +2N ₂ O=S ₂ N ₂ +Sa (ON) ₂ (1).
The mixture of acetylene and air is explosive, so this mixture can explode, it is possible to overheat the flame.

4. Assignment.

1. Follow the safety rules for gas welding.
2. To study the structure and operation of welding equipment.
3. Select the welding mode of low-carbon plate.
4 . Butt-weld or butt-weld the sample.
5. Apparatus for gas welding.
Gas welding devices (Fig. 2) include acetylene generator-1, oxygen cylinder-2, valve-3, reducer-4, burner-5, rubber hose-6.
5.1 Acetylene generators.
1 . In acetylene generators, acetylene gas is obtained by reacting calcium carbide with water .
All acetylene generators are classified according to the parameters of the burned fuel .
a) according to the principle of operation - "carbide to water" "water to carbide" Contact "squeezing out water";
b) productivity from 0.8 to 80m ³ /hour.
c) according to the type of installation - stationary and mobile;
g) according to the pressure limit of the generated gas - low (0.1 kg/cm ² )
5.2. Structure and operation of GNV-1.25 acetylene generator.
The GNV-1.25 acetylene generator (Fig. 3) is a movable medium-pressure generator that produces 1.25 m ^{3 of acetylene gas per hour.} The generator body is divided into two parts by 1 and 2. The retort 6 is located in the housing and is connected to the lower part of the housing with a tap 4 and a rubber hose 5. Water seal 9 is attached to the generator body. This valve is connected to the generator's gas gap through 2 rubber hoses 12 and 13.
Before work, tap 4 is closed and water is poured into the generator from the upper open part to the specified level. The water trap funnel 10 is filled with water up to the height of the faucet 8. The basket 7 is filled with calcium carbide and loaded into the retort and the retort lid is carefully closed.
After the generator is ready for operation, when the tap 4 is opened, water flows into the retort, and the acetylene gas formed by reaction (1) exits the retort to the lower part of the generator body, and squeezes the ground water up.
Acetylene pressure with the increase, water is compressed from the retort in the form of a cone to the level of the tap 4, as a result, the release of acetylene decreases, because the flow of water from the tap 4 to the retort 6 decreases.
Acetylene gas comes from the generator through pipe 13, hose 12 and water seal to the burner or burner. As the acetylene pressure decreases, water returns to the retort from the conical volume and acetylene release intensifies again.