Hand arc welding operation technology in various positions must master four actions:
A welding rod angle, B yaw motion, C steady arc motion, D select different lateral swing methods according to various welding positions. I. Arcing:
The welding process of manual arc welding starts from the arc striking, and the arc striking method has a scribing method and an arc striking method. 1. Scratch method is to first align the front end of the electrode to the weldment, then twist the wrist, so that the electrode is slightly scratched on the surface of the weldment, and the electrode is lifted by 2-4mm, that is, an arc is generated in the air, and then the arc length is maintained. The allowable range of electrode diameter. 2. Direct stroke method is to bend the wrist and the welding rod slightly touches the weldment. two. Shipment:
After the arc is ignited, the welding rod is quickly lifted by 2-4 mm for welding. The manual arc welding operation is composed of three basic actions: advancing in the welding direction, swinging in the lateral direction of the weld, and feeding the welding rod in the direction of the molten pool. There are two main methods:
1. Straight line method: Maintain a certain arc length during welding, and make a forward movement without swinging along the welding direction. In this way, the arc is relatively stable, and a large penetration can be obtained, but the weld bead is narrow.
2. Draw a circle-shaped moving strip method: make the end of the welding rod move in a continuous circle shape and move forward continuously. It is divided into two types: positive ring shape and oblique ring shape. The positive ring-shaped moving strip method is suitable for welding flat welds of thicker weldments. The advantage is that the molten metal can have a sufficiently high temperature to allow oxygen, nitrogen and other gases dissolved in the molten pool to have a chance to be precipitated, and at the same time facilitate slag. Upward floating; the inclined ring-shaped moving strip method is suitable for T-shaped and butt-crossing horizontal welding in the flat and up position, and is characterized in that it is advantageous for controlling the molten metal to avoid snagging and contributing to the formation of the weld. 3. Receiving the arc:
The closing end (arcing) of the arc-welding bead is not appropriate, and it is possible to form a crater below the basic metal at the end of the weld, which is prone to cracks. Common arc closing methods are:
1. Circle rounding method: suitable for thick plate welding, there is a danger of burning through the thin plate.
2. Repeated arc-breaking method: When welding to the end point, repeatedly extinguish the arc in the arc pit-ignition arc until the crater is filled. This method is suitable for thin plate welding, but it is not suitable for alkaline welding rods.
3. Reflow finishing method: When welding to the end point, do not extrude the arc and change the angle of the electrode appropriately, move it in the opposite direction, and then break the arc. This method should be used for the alkaline electrode.
The following is a brief introduction to the operation of several types of position welding:
First, flat welding
1) At the beginning, the inclination angle is appropriately increased, and the inclination angle is correspondingly reduced when the temperature is raised; 2) the angle between the welding wire and the welding torch is maintained at about 90°; 3) the welding wire is always immersed in the molten pool and continuously stirred and melted. Pool
4) The welding wire can be moved up and down when welding thin parts;
5) At the end, the torch slowly levees and shrinks the tail pool.
6) The linear speed of the welding rod should not be too slow, otherwise it will easily cause the slag to be too thick, and it is difficult to operate without seeing the molten pool.
Second, vertical welding
1) Welding should be carried out with a flame with a lower energy rate;
2) Strictly control the temperature of the molten pool, the area of the molten pool should not be too large, and the depth of the molten pool should be smaller. The welding current should be 10-15% smaller than the flat welding. ;
3) The welding torch should be inclined upwards at a certain angle along the welding direction, generally 60--80° with the weldment;
4) In order to control the temperature of the molten pool, the welding torch can move up and down at any time, so that the molten pool has a chance to cool, and the molten pool is properly heated; 5) The semi-circular arc-shaped lateral swing can be used to add arcing (arcing).
Third, horizontal welding
1) Use a lower flame energy rate to control the bath temperature;
2) The thin part is made by the left welding method. However, the torch should also be tilted upwards so that the flame flow directly faces the weld, and the pressure of the gas flow prevents the molten metal from flowing out of the weld pool;
3) When welding, the torch generally does not swing laterally, but when welding thicker weldments, it can make a small oblique circular motion. Fourth, overhead welding
1) welding with a flame with a lower energy rate;
2) The operation should strictly ensure the fusion of the roots on both sides of the groove, strictly control the size and temperature of the molten pool, and keep the liquid metal in a viscous state to prevent falling;
3) The groove angle should be slightly larger than the flat welding to ensure the operation is convenient, pay attention to the operating posture, pay attention to metal splash and falling liquid metal burns.
4) When welding the first layer of the butt weld of the groove, the electrode is at an angle of 90° to both sides of the groove. It is 70-80° angle with the welding direction. The shortest arc is used for the push-pull action. The molten pool should be thin and not thick, and ensure good fusion with the base metal. When the temperature of the molten pool is too high, the arc can be raised to lower the temperature slightly. When welding the remaining layers, the welding rod is yawed and the arc is acted on both sides.
