Classification
Three factors affecting the efficiency of spot welding machine use
Release time:
Dec 14,2023
● Pressurization
Pressurization of the spot welder is an important factor in heat generation. Pressurization is a mechanical force applied to the weld, which reduces the contact resistance and makes the resistance value uniform, prevents local heating during welding, and makes the welding effect uniform.
● Energizing time
The time of energization is also an important factor in the generation of heat. The heat generated by energization is applied by conduction, and even if the total heat is certain, the maximum temperature of the weld is different due to the difference in the time of energization and the welding result is not the same.
● Current waveform
The optimum combination of heat generation and pressurization in time is very important for a spot welder, and for this reason the temperature distribution at each instant during the welding process must be appropriate. Depending on the material and size of the object to be welded, a certain amount of current will flow for a certain period of time. For the heating of the contact part, if the pressurization is slow, it will cause local heating and deteriorate the welding effect of the spot welder. In addition, if the current stops sharply, the welding part of the sudden cold will produce cracks and material embrittlement. Therefore, a small current should be applied before or after the passage of the main current, or a pulse should be added to the rising and falling currents.
Example: For thick plates and press molded parts, where deformation and strain exist, a small current is passed before the main current is passed for preheating in order to make a tight bond between the plates after welding.
Example: For materials that are subject to heat hardening or cracking, annealing is performed by applying a small amount of current for post-heating after the main current has flowed.
● Surface condition of the material
The contact resistance is directly related to the heat generated at the contact area. At a certain pressure, the contact resistance is determined by the surface condition of the weldment, i.e., after the material is determined, the contact resistance is determined by the fine dimples and the oxide film on the surface of the metal. Fine bumps are good for obtaining the desired heating range of the contact resistance, but the presence of oxide film increases the resistance and leads to localized heating, so it should be removed.
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