Laser welding and laser cutting principle

1 Laser welding

Laser welding is mainly a high energy density laser beam as a heat source, in the power density of less than 104 ~ 105W/cm2, the heat conduction heating the surface of the workpiece, slow welding, welding melt depth shallow; or in the power density of more than 105 ~ 107W/cm2, through the control of laser pulse peak power, width, repetition frequency, energy to promote the melting of the workpiece and the formation of a specific melt pool, for Fast welding, welding depth of fusion is larger.

 

2 Laser cutting

Laser cutting mainly refers to the use of laser cutting materials, which requires the use of optical devices to guide the output of high power laser beam. At the same time, according to the motion control system in the laser to track the trajectory of the workpiece to be cut, the laser beam is focused on the material, prompting the material to melt, evaporate, burn, blow away and other reactions to obtain a high surface finish edge.

 

Laser welding in the pole ear welding application

1 Welding device selection

According to the pole lug welding requirements, welding processors can choose semi-automatic welding device or fully automatic welding device. The former is mainly handheld laser welding machine, which is mainly a disc structure, every interval of 90 ° for the opening of the V-slot, V-slot can be placed in the battery cylinder parts, pressed parts after focusing the laser beam to the welding site, each welding a part for 90 ° rotation, the second welding point is rotated 0.50 mm; the latter is through the straight funnel way of feeding, each after a "round pit", V-slot are automatically put into the battery cover, the battery body to be welded, for automatic welding. Commonly used laser welding equipment for SOUPACT compact laser assembly welding equipment, Tide laser welding system, etc.

 

2 Welding parameters settings

Considering the current soft pack lithium-ion batteries for a variety of negative aluminum and copper convergence welding mode, copper lug thickness in the 0.2-0.5mm, aluminum lug welding thickness in the 0.2 to 0.6mm or so. Therefore, laser welding lug, you need to set the laser wavelength of 1064nm, laser power of 110W ~ 200W, spot 28μm, laser scanning speed and pulse frequency of 500mm / s, 200kHz, repeat frequency of 0.4 ~ 20MHz, pulse width of 50-120ns. and control lug welding gap The width of the lug welding gap is within 1.2-2.4mm and the depth of the welding gap is within 1.2-1.8mm. Also ensure the accuracy of the lug width and lug spacing accuracy, lug height accuracy are less than or equal to ± 0.15mm.

 

3 Welding process control

Currently, in the process of lug laser welding, semi-automatic welding method is used less, to fully automatic welding is more common.

 

In the fully automatic welding process, the welding process is as follows: first of all, you need to start the device to carry out the detection of the position of the parts to be welded, only the battery cover, the main body of the battery to be welded are in the correct position, before starting the welding, turning flat, under the material, shifting and other processes.