电阻焊 is a thermo-electric process where heat is generated at the interface of the parts to be joined by passing an electrical current through them or a precisely controlled time and under a controlled pressure (also called force). The name “resistance” spot welding derives from the fact that the resistance of the workpieces and electrodes are used in combination or contrast to generate the heat at their interface.
Resistance spot welding is a fairly simple heat generation process: the passage of current through a resistance generates heat. This is the same principle used in the operation of heating coils. In addition to the bulk resistances, the contact resistances also play a major role. The contact resistances are influenced by the surface condition (surface roughness, cleanliness, oxidation, and platings).
热量 = I2 x R x t x K
Where “I” is the weld current through the workpieces, “R” is the electrical resistance (in ohms) of the workpieces, “t” is the weld time (in hertz, milliseconds or microseconds), and “K” is a thermal constant. The weld current (I) and duration of current (t) are controlled by the resistance welding power supply. The resistance of the workpieces (R) is a function of the weld force and the materials used. The thermal constant “K” can be affected by part geometry, fixturing and weld force.
The bulk and contact resistance values of the workpieces, electrodes, and their interfaces both cause and affect the amount of heat generated. The diagram (above right) illustrates three contact and four bulk resistance values, which, combined, help determine the heat generated.
参见 点焊 了解更多信息
如欲了解有关电阻焊工艺的更多信息，请阅读 《电阻焊基本原理》, 精点电阻焊应用 和 大型点焊应用。