Intermittent arc welding

Single-sided welding double-sided forming is a single-sided welding way to obtain double-sided forming of the weld, can omit the flip welding parts and back root cleaning process, especially suitable for the situation can not be double-sided welding. Generally, there are two welding methods: intermittent arc welding (arc welding and continuous arc welding (continuous arc welding). Today we will first learn intermittent arc welding! What is intermittent arc welding? Indirect quench arc welding is a kind of welding technology which controls the shape, temperature and thickness of liquid metal in the molten pool by controlling the time of arc burning and quench as well as the movement of strip. It is easy to control the state of weld pool and has low requirements on the assembly quality and welding process parameters. However, it has high requirements for welders’ operating skills. If it is not properly operated, it will produce defects such as porosity, slag inclusion, edge biting, welding tumors and bead protruding. The commonly used operation methods of arc welding are one point method, two point method and three point method. Commonly used arc welding operation method One point method is suitable for welding thin plate, small diameter tube and small gap welding conditions; Two point method and three point method are suitable for welding thick plate, large diameter pipe and large gap condition. The one-point and two-point methods are most commonly used. 1) Basic operating points of the two-point method First, the arc is ignited on the groove surface about 10~15mm in front of the beginning welding end, and then the arc is pulled back to the starting welding place and a little swing, and the arc is depressed after 1~1.5s of preheating the welding part. When hearing the sound of “chi” from the arc penetrating the groove, it can be seen that the positioning weld and the two sides of the connecting groove begin to melt. When the first molten pool is formed, the first molten pool is often called the molten pool block. When the first molten pool is not completely solidified and the center of the molten pool is still in a semi-melting state, the arc is re-ignited and the welding part root is punctured at a certain electrode Angle on the groove surface in front of the left of the molten pool. When breakdown, the short arc is heated to the root of the welding part for 1~1.5s, and then the electrode is quickly picked along the opposite direction of the welding. When they hear “bursts” of the weldment was breakdown, shows the first melt hole has been formed, should quickly make a long arc column (flat welding for one-third of the arc column, vertical welding is 1/3 ~ 1/2 of arc column, horizontal and overhead welding for 1/2 of arc column) with molten drops through the melt hole, make it separately from molten metal on the back, positive form on the back and front side weld pool. At this time to quickly extinguish the arc, otherwise it will cause burning through. Arc extinction is about 1s, that is, when the molten pool is not completely solidified, and there is a yellow light point as large as the diameter of the electrode, the arc is immediately ignited, and the first molten pool right in front of the breakdown welding. Then follow the above method to complete the subsequent weld. 2) Basic operating points of one-point method The one-point method is the same as the two-point method for establishing the first molten pool. When welding, the arc should melt the blunt edge on both sides at the same time. After hearing the sound of “chi”, the arc is extinguished decisively. Generally, the arc extinguishing frequency is kept at 70~80 times per minute. The dip Angle of the electrode and the penetration depth of the hole to the root of the groove are the same as that of the two-point method. 3) Arc extinguishing time control of arc extinguishing welding The control of arc extinguishing time is the key point of arc extinguishing welding and the key to guarantee welding quality. Generally, the length of arc extinguishing time can be controlled according to the temperature and size of the weld pool. The picture During welding, the transition from high temperature to low temperature can be determined by the color change of the molten pool. When the temperature of the molten pool is high, it shows a bright yellow color. With the decrease of temperature, it gradually changes to yellow red and dark red. The size of the molten pool also gradually decreases from the outside to the inside. Generally, arc extinction welding is to ignite the second arc when the molten pool gradually turns yellow and red after the arc is extinguished and the diameter is reduced to 1/2~1/3, the time is about 0.5~1s. Due to the different welding position of the arc extinguishing time is different, the operator can adjust the arc extinguishing time according to the actual welding situation. 4) Operation points of arc welding in various positions (1) Main points of flat welding operation The hole of flat welding is easily covered by liquid metal at the moment of breakdown, which is generally not easy to see. Therefore, attention should be paid to the welding, when hearing the “chi” sound of arc breakdown, to quickly extinguish the arc, otherwise it is easy to produce welding tumor or hole is too large. The back of the weldment shall be kept 1/3 of the arc column length. The first layer of bottom welding to ensure that the arc should be short, the transmission droplet should be thin, interrupted arc extinguishing cycle should be short. (2) Main points of vertical welding operation During vertical welding, molten metal and droplet have a tendency of falling due to gravity, which is easy to produce welding nodules. And because the slag is easy to separate, welders can clearly observe the shape and state of the pool for easy operation and control of the pool. If the operation or transport Angle is not appropriate, it is easy to produce air holes. During the operation, it is necessary to master the dip Angle of the electrode, arc extinguishing frequency and arc length, and keep the back of the welding part 1/3~1/2 arc column length. (3) Main points of horizontal welding operation The first layer of horizontal welding, due to the influence of gravity transition droplet, easy to deviate from the electrode axis downward deflection. Therefore, the welding rod must be maintained at a certain elevation Angle (the electrode leading end is higher than the electrode holding end) during operation, and short arc welding is used. Due to the tilt of the electrode and the Angle of the upper and lower groove, the arc heating of the upper and lower groove is not uniform, the upper groove heating is better, the lower groove heating is poor. At the same time, the molten pool metal falls down due to gravity, easily resulting in poor downhill fusion, or even cold connection. Therefore, should be the first breakdown of the slope surface, after the breakdown of the slope surface, and the breakdown position staggered a certain distance (0.5~1 hole distance), so that the slope surface breakdown hole in the front, the slope surface breakdown hole in the back. During welding, the back of the weldment shall be kept 1/2 arc column length. (4) Main points of inverted welding operation In the inverted welding, the droplet transition form is mainly short circuit transition, that is, relying on arc pressure and metal surface tension to transfer to the molten pool. Because the gravity of the droplet metal of the electrode hinders the droplet transition, the pool metal is also affected by its own gravity. The higher the temperature of the pool, the smaller the surface tension, so it is easy to produce depression on the back of the weld bead and weld tumor on the front. Therefore, the breakdown current of inverted welding is large, and the operation of short arc should be carried out. At the same time, the volume and temperature of molten pool should be controlled, and the welding layer should be thin. During welding, the back of the weldment shall be 1/2 arc length. During welding, replacing the electrode is one of the key points in the operation of single-sided welding and double-sided forming. If not handled properly, cold shrinkage holes may occur at the joint. Before extinguishing the arc should be rapidly continuous arc at the edge of the molten pool, so that the electrode drops 2~3 drops of molten iron, so as to achieve the purpose of filling the molten pool and slow cooling. Then the arc is depressed and moved to a groove surface, and then quickly extinguish the arc, quickly replace the electrode. After changing the electrode, first in the distance from the weld joint end of 10~20mm on any groove surface arc, and then make the arc from the groove surface side around to the joint end heating. Then the arc is sent to the root, so that it becomes the first molten pool after the replacement of the electrode, and then can turn to normal welding.铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods