1959: DeVille and Debray invented hydrogen-oxygen welding.
188 1 year: the earliest carbon arc welding machine was invented by Demery Ence, a Frenchman.
1 working principle, the working principle of ordinary welding machine is similar to that of transformer, which is a step-down transformer. The two ends of the secondary coil are the workpiece to be welded and the coated electrode, which ignite the arc and generate a heat source at the high temperature of the arc to weld the gap between the workpiece and the coated electrode.
Welding transformer has its own characteristics, that is, the voltage drops sharply. Covered electrode voltage drops after ignition; When the covered electrode is short-circuited due to adhesion, the voltage also drops sharply. The reason for this phenomenon is the iron core characteristics of welding transformer. The working voltage of the welding machine can be adjusted not only by a 220/380 voltage conversion, but also by the tap of the secondary coil. At the same time, it can be adjusted by iron core. The more the iron core enters, the smaller the welding voltage will be.
2 principle of electric welding. In fact, the principle of electric welding is that the voltage is reduced and the current is enhanced by the voltage reducer in the electric welding machine, and the huge heat generated by electric energy is used to melt steel. The integration of coating and covered electrode makes the fusion between steel higher, and the coating on the outer layer of covered electrode plays a very important role.
The covered electrode used in manual arc welding consists of two parts: the coating and the flux core. When welding, the electrode, as an electrode, on the one hand plays the role of conducting current and initiating arc, so that a continuous and stable arc is generated between the electrode and the base metal, providing necessary heat for melting welding. On the other hand, covered electrode, as a filler metal, is added to the weld and becomes the main component of the weld metal. Therefore, the composition and quality of covered electrode will directly affect the chemical composition, mechanical properties and physical properties of weld metal. In addition, covered electrode has a great influence on the stability of welding process, the appearance quality of weld and welding productivity.
The welding core is the metal core of covered electrode. In order to ensure the weld quality, there are strict regulations on the content of various metal elements in the weld core. In particular, there are strict restrictions on harmful impurities (such as sulfur and phosphorus). ), and the quality of core metal is better than that of base metal.
Without coating, the polished rod covered electrode cannot be arc welded. This is because of poor arc stability, large spatter and poor weld formation. After long-term practice, it is gradually found that coating some mineral raw materials (i.e. coated covered electrode coated) on the core can greatly improve the performance of coated covered electrode.