There are several welding methods for electric welding.

Manual welding, that is, manual arc welding, is a manual welding method that uses electric arc as heat source to melt covered electrode and the base metal to form a weld. According to the process standard of manual arc welding, it mainly includes four welding methods: flat welding, vertical welding, horizontal welding and overhead welding:

(1) flat welding

1. Select qualified welding process, covered electrode diameter, welding current, welding speed, welding arc length, etc. And verified by welding process test.

2. Cleaning the weld: Before welding, check whether the groove and assembly gap meet the requirements, whether the tack welding is firm, and there shall be no oil stain and rust around the weld.

3. Baking the covered electrode shall conform to the specified temperature and time, and the covered electrode taken out of the oven shall be put in a covered electrode heat preservation barrel for immediate use.

4. Welding current: According to the thickness of weldment, welding grade, covered electrode model, diameter, welder's proficiency and other factors, choose the appropriate welding current.

5. Arc striking: The arc point of fillet weld should be at the end of the weld, which should be greater than10 mm. Arc striking is not allowed casually. After arcing, the covered electrode should be removed from the weld zone immediately, so that a gap of 2 ~ 4 mm can be kept between the covered electrode and the components to generate an arc. Butt welds shall be connected and fillet welded in time. Arc striking plates and lead-out plates shall be set at both ends of the weld. Before welding to the welding area, the arc striking plate must be used. The intermediate joint should be placed at the position 15 ~ 20 mm before the weld. After the weldment is preheated, the coated covered electrode should be put back at the beginning of the weld, and the molten pool can be filled to the required thickness before welding.

6. Welding speed: constant speed welding is required to ensure the consistency of the thickness and width of the weld. It is advisable to keep the same distance (2 ~ 3 mm) between molten iron and slag and the inside of the mask.

7. Welding arc length: determined according to different covered electrode models. Generally, the arc length is required to be stable, and the acidic covered electrode is generally 3 ~ 4 mm, and the alkaline covered electrode is generally 2 ~ 3 mm ..

8. Welding angle: According to the thickness of two weldments, the welding angle has two aspects. One is that the included angle between covered electrode and welding direction is 60 ~ 75; Second, there are two angles between covered electrode and welding. When the thickness of weldments is equal, the included angle between covered electrode and weldments is 45; When the weldments are not equal in thickness, the included angle between covered electrode and thicker weldments should be greater than that between covered electrode and thinner weldments.

9. Arc closing: After each weld is welded to the bottom, the arc pit should be filled, and the arc belt should be in the opposite direction to the welding, so that the arc pit can be left in the weld to prevent the arc pit from biting meat. Arc plates shall be cut off by gas cutting after welding, and polished flat. It is not allowed to shoot them down with a hammer.

10. Slag removal: after the whole weld is welded, slag removal and welder's self-inspection (including appearance and weld size, etc.). ) prove that there is no problem, you can move the welding to another place to continue.

(II) Vertical welding: The basic operation process is the same as that of flat welding, but the following issues should be noted:

1. Under the same conditions, the welding power supply is less than the flat welding current 10% ~ 15%.

2. When short arc welding is adopted, the arc length is generally 2 ~ 3mm. ..

3. The covering electrode angle is determined according to the thickness of the weldment. The thickness of the two weldments is equal, and the included angle between covered electrode and covered electrode is 45; When the thickness of two weldments is different, the included angle between covered electrode and the thicker weldment should be greater than that of the thinner weldment. Covered electrode should form an angle of 60 ~ 80 with the vertical plane, so that the arc is slightly upward and blows to the center of the molten pool.

4. Arc closing: When the welding is finished, the arc pit is filled with arc opening method, and the arc is moved to the center of the molten pool for arc closing. It is forbidden to throw the arc pit aside. In order to prevent meat biting, the angle of covered electrode should be changed by lowering the arc, so that the covered electrode is perpendicular to the weldment or slightly blown down by the arc.

(3) Horizontal welding: basically the same as horizontal welding, the welding current is less than 10% ~ 15% under the same conditions, and the arc length is 2 ~ 4 mm At the angle of covered electrode, during horizontal welding, the covered electrode should be inclined downward at an angle of 70 ~ 80 to prevent molten iron from falling. According to the different thickness of the two weldments, the covered electrode angle can be adjusted appropriately, and the covered electrode and the welding direction are 70 ~ 90.

(4) Overhead welding: basically the same as vertical welding and horizontal welding. The included angle between covered electrode and weldment is related to the thickness of weldment, and the included angle between covered electrode and welding direction is 70 ~ 80, so it is appropriate to use small current short arc welding.