Transmittance testing method and device for laser welding plastics

Abstract

The invention relates to the technical field of laser welding, in particular to a method for testing transmissivity of a laser welding plastic and device and a device. The method comprises the steps as follows: step one, a laser device emits lasers, and then a thermal infrared imager is used for shooting, so that a temperature image for lasers emitted by the laser device is obtained, the image is converted into a digital signal, an image capturing card outputs the signal into a computer, and the computer acquires the laser temperature To; step two, an object to be tested is placed between the laser device and the thermal infrared imager, the lasers emitted by the laser device transmit the object to be tested, and the thermal infrared imager is used for shooting, so that a temperature image of the object to be tested is obtained, then the image is converted into a digital signal, the image capturing card outputs the signal into the computer, and the computer acquires the temperature Tt of the objected to be tested; and step three, the computer starts to calculate the transmissivity T of the laser welding plastic, and the transmissivity calculation formula is as follows: T=Tt / To. Before welding, the transmissivity situation of the plastic can be known with the measuring method and the device.

Description

technical field [0001] The invention relates to the technical field of laser welding, in particular to a transmittance testing method and device for laser welding plastics. Background technique [0002] Laser welding is a technology that uses the heat generated by a laser to melt the contact surfaces of plastics, thereby bonding thermoplastic sheets, films or molded parts together. [0003] Infrared laser is used as the welding heat source, generally the laser in the band of 800nm~1100nm is the main one. The laser in this band has a relatively low absorption rate for most transparent or colored hot-melt plastics that can be welded. When the laser passes through these materials The energy loss is very small, and the upper and lower layers of materials stacked together during welding need to meet certain requirements: the upper layer of material is a transmission area, and the laser used for welding should have a higher transmittance; while the lower layer of material is a the...

AI Technical Summary

Problems solved by technology

Therefore, conventional transmittance measurements provide insufficient information on the weldability of plastics, as conventional transmittance measurements do not have any information on the thermal properties of the plastic material or heat loss due to reflection on the polymer surface

Additionally, semi-crystalline plastics or filled polymers are difficult to measure transmittance because those materials scatter light under laser light, limiting traditional transmittance measurements / limiting traditional methods for measuring transmittance in thermoplastics

[0009] Experimental results and actual welding surfaces: plastics with low transmittance are not suitable for laser welding

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