一． background knowledge

In the power battery system, excess heat is generated by the battery operation, and the heat is transferred through the contact between the battery or the module and the surface of the plate-shaped aluminum device, and is finally taken away by the cooling liquid passing through the internal flow channel of the device. This plate-type aluminum device is a water-cooled plate.

(Water cooling plate in power battery pack)

(water cooling plate)

With the rapid development of the new energy vehicle industry, the demand for power battery packs has grown rapidly, and the production capacity of the key component, the water-cooling plate used for battery cooling, is also increasing.

The air tightness and installation accuracy of the power battery water-cooled plate are very high, so it is necessary to strictly test the welding quality and flatness of the water-cooled plate. The traditional offline detection methods are inefficient. For large water-cooled plate workpieces, they are bulky, heavy, and complex in structure. Traditional measurement methods represented by rulers, marking machines, and three-coordinate measuring instruments have the following detection difficulties:

l The detection process is time-consuming and labor-intensive, and the larger the size, the greater the cumulative deviation;

l The detection parameters are limited, and it is difficult to measure the curved surface, occlusion surface, corner and other parts;

l Traditional inspection tools will be worn out after long-term use, which will directly affect the inspection results;

l The three-coordinate precision is high, but for large workpieces, the cost is high and the convenience is poor.

Therefore, the reliability of manual inspection cannot be guaranteed, and for large boards, traditional methods cannot cover the entire area of inspection at the same time. Therefore, the need for real-time automatic detection is very urgent.

launched by Nextvision Technology for this application scenario is based on the integrated large field of view 3D line laser camera LVM-2050 and the binocular dual line laser camera LVM-3135, which can meet the online inspection requirements of new energy vehicle water-cooling panels. The equipment based on this scheme has been applied to the largest water-cooled panel production line for new energy vehicles in China.

二． Water-cooled plate inspection scheme

Nextvision's integrated 3D camera (LVM-2050 and LVM-3135) three-dimensional scanning system solution cooperates with the detection system software, which can scan all the required structures of the water-cooling plate very quickly, and perform data processing through 3D point cloud data processing. Flatness measurement and detection of defects.

2.1 Using the camera

All-in-one 3D line laser cameras LVM-2050 and LVM-3135.

The LVM-2050 has 2048 physical contour points in the X direction, the maximum FOV width of the field of view is greater than 330mm, and the Z-direction depth of field is greater than 350mm. The capture speed in full frame is 340 frames per second. It is suitable for high-precision high-speed measurement of large-scale fabric parts.

The characteristic of LVM-3135 binocular dual laser camera is that the laser line is not vertically incident, which can perfectly eliminate occlusion, in comparison. The binocular and single laser products of friends and merchants, the laser line is vertical, and there will be blind spots when scanning thin walls. LVM-3135 is suitable for high-precision detection of defects such as pores, blisters, and creep.

(full view of equipment)

2.2 Detection method

l Flatness detection: Scan the spatial point cloud data of the workpiece through a 3D camera, and fit the ideal least squares plane for each detection area. Detects the difference from the fitted plane in the point cloud data.

l Bevel profile: take point fitting and compare with the benchmark.

l Defect detection: Blob, template matching, etc.

2.3 Testing Equipment

l The integration method of multi-camera combination is adopted. Take the new energy battery water-cooling board detection of a platform as an example: two LVM-2050s are installed side by side in the rack above the equipment, and two LVM-3135s are installed in the rack below the equipment. The frame can be moved in X and Y directions to drive the camera to complete the high-speed scanning of materials. 

2.4 performance

l Flatness 0.3mm

l Board Aperture ±0.1mm

l Board face position degree 0.3mm

l Beat: < 60s/ piece (covering 1 5 00mm* 75 0mm products, 40 holes for holes) 

(Example of water cooling plate scan )

l LVM-2050 camera features: X- direction 2048 physical contour points, the maximum FOV field of view width is greater than 330mm, and Z -direction depth of field is greater than 350mm. The capture speed in full frame is 340 frames per second. High-precision, high-speed measurement for large-scale fabric pieces.

l LVM-3135 binocular dual laser camera features: The laser line is not vertically incident, which can perfectly eliminate occlusion. It is suitable for high-precision detection of defects such as pores, blisters, and creep.

(LVM-2050 camera working diagram )

(LVM-3135 camera working diagram )