Operation and technique of Arc welding 1
1. The arc welding equipment is a kind of equipments to provide electricity for the arc, referred to as electric welding machine.The precautions for use is as below:
1) Check whether the wiring is correct, and the equipment shell must be grounded. When the welder gets an electric shock, the power supply should be cut off before rescue.
2) Push and pull the power switch should be worn dry gloves, do not face the switch, so as to avoid arc spark and burn the face.
3) Welded cable is not allowed to be placed near the welding machine or on the hot metal weld, but also to avoid collision and wear.
2. The power should be cut off in time when stopping working, and the equipment should be covered when working outdoors.
3. Selection of the welding current
1) In the actual production process, welders all choose the welding current according to the test results of trial welding and according to their own practical experience.
2) The current is too small, it is difficult to lead the arc, the welding rod is easy to stick to the welding parts, the fish scales are thick, and the fusion of both sides is not good.
3) The current is too large, welding splash and smoke, welding rod red, the melting pool surface is very bright, easy to burn through, bite the edge.
4) The current is appropriate, easy to lead arc arc stability, splash is very small, can hear the uniform split sound, weld on both sides of the smooth transition to the mother material, the surface fish scales are very fine, welding slag is easy to knock off.
4. Selection of electric arc voltage
Arc voltage mainly affects the width of the weld. When welding electrode arc welding, it is mainly controlled by the lateral swing of the electrode, so the influence of arc voltage is not great. When the welding current is adjusted, the longer the arc, the higher the voltage. However, when the arc is too long, the combustion is unstable, splashing, easy to produce bites, air holes and other defects; if the arc is too short, it is easy to stick to the electrode, generally, the arc length is equal to 1 / 2 or 1 times of the diameter of the electrode.
5. Selection of welding speed and number of weld layers.
Welding speed refers to the length of the weld completed within unit time.
Under the principle of ensuring the required size and shape and good fusion, the welding speed is flexibly controlled by the welder. In thick plate welding, multi-layer welding or multi-channel welding must be used. The former weld path preheat the latter one, and the latter one heat treats the former one. It is beneficial to improve the toughness and toughness of the weld metal. The weld path thickness of each layer shall not be greater than 1.5 times of the electrode diameter.
6. Weld electrode using skills:
When the arc welding begins, the process of igniting the welding arc is called the arc. The method of arc introduction includes the following two categories:
1) Non-contact arc refers to the use of high frequency voltage to make the gas conductivity between the electrode end and the welding part produce an arc. This method is rarely used in welding electrode arc welding. When contacting the arc, short circuit the electrode and the welding piece, and then open the electrode to ignite the arc. According to the different operation techniques, it can be divided into two kinds: stroke method and scratch method.
Stroke method: make the electrode and the surface of the welding vertical contact, when the end of the electrode and the surface of the welding gently touch, then quickly lift the electrode and maintain a certain distance, immediately ignited the arc. The welder must master the time and distance of the wrist movement up and down.
Scratch method: first align the end of the electrode at the weld, and then wipe the electrode on the surface of the weld, when the arc lead and then while the metal has not begun a lot of melt moment, immediately make the distance between the end of the electrode and the welded surface maintained at a distance of 2~ 4mm, the arc can be burned steadily. If the electrode and the welding parts stick together, as long as the electrode left and right shake a few times, it can be removed from the weld. If the electrode can not be separated from the weld at this time, you should immediately relax the welding clamp, make the welding circuit disconnected, and then remove the welding rod after the electrode is slightly cold.
2) Application: Due to the low temperature of the arc end, the melting depth is shallow, and it is easy to produce unpenetration. The acid welding rod can be slightly extended to lead the arc, preheating the root of the groove, and then lower the arc for normal welding. Alkaline welding rod is beneficial to the penetration of the root, it is not necessary to use the arc of acid welding rod, but do not directly arc, should be in the front of the groove, quickly pull back the welding end, and lower the arc for welding.