Method for detecting resistance welding strength of lithium ion battery, and apparatus thereof

Abstract

The invention discloses a method for detecting the resistance welding strength of a lithium ion battery. The method comprises the following steps: irradiating the conductive connection sheet of the lithium ion battery to be detected and resistance welding spots of the housing of the battery through using a white coaxial light source; acquiring and amplifying welding spot images, and transmitting the images to a computer; and extracting and analyzing the gray value and the area parameter of each pixel point in the welding spot images, comparing the analytic result with preset welding spot characteristic parameter threshold values, and judging whether the strength of the welding spot is qualified. The method which adopts a noncontact and nondestructive optical imaging mode to detect the welding spots has no damages or destroys to the welding spots, has the advantages of accurate and efficient test process, realization of 100% online full detection, effective reduction of faulty welding risks, and satisfying of practical needs of large-scale production. Additionally, the invention also discloses an apparatus for detecting the resistance welding strength of the lithium ion battery.

Description

technical field [0001] The invention relates to a method and device for detecting welding strength, in particular to a method and device for detecting resistance welding strength of a lithium ion battery. Background technique [0002] In recent years, with the rapid development and wide application of lithium-ion battery products, the requirements for safety and product quality are also increasing. Therefore, it is very important to ensure the reliability of the internal solder joints of lithium-ion batteries. [0003] At present, for the welding of the anode conductive connecting piece (T2 material copper strip) and the battery case (cold-rolled nickel-plated steel case) inside the cylindrical 18650 lithium-ion battery, the industry generally adopts the resistance welding process. However, the melting points of these two metal base materials are quite different, copper is 1080°C, and steel is 1530°C; the thermal conductivity of the two is also very different, copper is 401W...

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Problems solved by technology

For example, Chinese patent application No. 201020526039.4 provides a resistance spot welding spot detection device, Chinese patent application No. 200610097980.7 provides a curtain wire solder spot detector, and Chinese patent application No. A detection device for the welding strength of the tabs of lithium-ion batteries. The common feature of the three is: the mechanical tensile strength is tested by applying an external force to the weld. This is a destructive test, and the test itself will affect the reliability of the solder joints. cause a certain degree of impact, especially for solder joints whose tensile strength is close to the specification control line; in addition, the above method needs to use specific fixtures, which will affect the efficiency, so it is generally only suitable for sampling inspection, and it is difficult to apply in large 100% full inspection and monitoring is carried out in large-scale continuous production, so that the solder joint strength of the product inevitably has certain quality risks and potential safety hazards

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