Spot welding

About: Spot welding is a research topic. Over the lifetime, 12491 publications have been published within this topic receiving 89845 citations. The topic is also known as: Spot_welding.

An effective quality assessment method for small scale resistance spot welding based on process parameters

Abstract: With the rapid development of microelectromechanical system technology, small scale resistance spot welding (SSRSW) is ever-increasingly used in electronic and medical devices. Whereas there is limited research work dealing with quality control of SSRSW. This paper treated the U–I (voltage–current) curve as the monitoring signature to explore a real-time and in-situ SSRSW quality monitoring method. First a systematic research on the U–I curve was performed and then five factors extracted from the U–I curve to estimate the weld quality through an artificial intelligence algorithm was proposed. The entire predictions match with their actual results well, showing that the U–I curve is a reliable quality monitoring signature for SSRSW. It can assess the weld strength and nugget diameter in small error on condition that the resistance welding power supply used during the whole welding process can provide linear direct current (DC) or high frequency (HF) current, which is commonly employed in SSRSW.

Critical design parameters of the electrode for liquid metal embrittlement cracking in resistance spot welding

Abstract: The present work studied the influence of the geometric design of the electrode on Zn-assisted liquid metal embrittlement (LME) cracking during resistance spot welding (RSW). LME cracking of the galvannealed transformation-induced plasticity (TRIP) steel welds, induced by two types of electrodes, a radius type with different radius of curvature (R), and a dome type with variable tip diameter (d), was studied both experimentally and by simulation. The current density decreased and the contact area at the electrode/sheet (E/S) interface increased with the increasing R, resulting in low temperatures and thermal stress, which subsequently led to decreased LME tendency. On the contrary, the current density decreased but the initial contact area at the E/S interface remained unchanged with increasing d, causing only a minor reduction in the temperature and hence less influence on LME cracking. These results suggested that R is the most critical design parameter of the electrode that controls LME cracking. Moreover, the radius type electrode displayed lower LME sensitivity as compared with the dome type electrode. This is attributed to the fact that the radius type electrode provides the benefits of increase in both R and d.

Spot welding method

Abstract: A spot welding method according to the present invention has steps for a preparatory application of current, a first application of current, a second application of current, and a third application of current. Preparatory application of current: A welding current is gradually increased (in an upslope manner, for example) in order to improve the fit of the contact surfaces between steel plates and to reduce plate gaps. Because rapid loading of current causes current application to be localized and then splash occurs as a result of the welding of sections where current is applied, current is applied gradually (in an upslope manner, for example) and localized heating is avoided. First application of current: The contact surfaces between the steel plates are fit by the preparatory application of current, a fixed welding current is applied when the contact surfaces have been fit, and a nugget is produced by the heat that is generated from the electrical contact resistance between the plates. Second application of current: The current is reduced below the level of the first application of current and the nugget is made to grow in the radial direction while internal splash is suppressed. Third application of current: When the diameter of the nugget reaches a certain size during the second application of current step, the current is increased above the level of the second application of current, and the nugget is made to grow primarily in a plate-width direction as well as in the radial direction.