All kinds of plastic products can be seen everywhere in our production and life. The processing methods of plastic materials are also various. There are only 15 Ways to soldering thermoplastics, such as heating tool welding, ultrasonic welding, vibration friction welding, etc. But for the three dimensional geometry, hollow body, large parts and other products, there are more or less technological problems in the above processing methods, and laser welding solves these problems well.
At present, the methods of laser welding plastic can be divided into non-contact laser welding and laser transmission welding. Here we mainly introduce laser transmission welding. Laser transmission welding refers to the technology that the laser beam passes through the surface of the laser plastic to reach the surface of the absorbing laser plastic, and the heat generated by the laser beam acts on the contact surface, melting the plastic contact surface, and then bonding the thermoplastic parts together. This way can be used in welding welding lap joints, and can be applied to welding butt joint, manufacturing has also been gradually applied in automobile clutch, brake parts, engine, car lights in the getty.
The principle of laser welding of plastics is: two kinds of plastics under low pressure are clamped together by mirror optical system, lens or optical fibers, the beam of light from a laser focus on the welding area, the formation of the heated region, which is a kind of plastic transmission for near infrared laser, another kind of plastic the absorption of laser, laser energy absorption plastic energy into heat energy, the contact surface of molten plastic, plastic surface and heat conduction to the transmission of near infrared light, the formation of the melting zone. Under the action of clamping force, the melting area produces intermolecular mixing. When the size of the melting is up to the specified requirement, the laser heat source is removed, and the weld is formed after cooling under certain pressure, and then the transmission laser plastic welding is realized. In order to improve the absorbability of the upper plastic, absorbent is often added. In addition, in order to improve the permeability of the plastic, high permeability dyes are often added.
The main advantages of laser plastic welding are:
1) the use of high energy density laser heat source to realize the optimization of the plastic joint surface temperature, so as to ensure the high speed and high precision of the plastic laser welding process.
2) through the change of the shape and size of the laser beam, the heat affected zone and the joint area can be controlled to a very small degree. The outer surface of the welding area can not see the trace of the welding, and the damage caused by the welding can not be seen.
3) the parts are assembled well before welding, and the welding process is very easy.
4) there is no limit to the shape and size of the parts, so that the design freedom of the parts is improved by a leap.
5) there is no vibration during the welding process, which is very favorable for the vibration sensitive components such as electronic components and medical instruments.
6) non-contact processing (the connected parts and heat sources have no physical contact), and it is easy to maintain the health and safety of medical and food equipment.
7) laser beam transmission with high free degree of freedom, easy to realize automation.
8) no toxic smoke and so on, the welding site is safe and reliable.
Transmission laser welding heat source
Laser transmission welding uses infrared laser as the welding heat source, the wavelength is 980nm, and the power level is based on the welding size and material. 30W-200W optical fiber output semiconductor laser is generally selected. JCZ 60W-200W semiconductor laser, a high precision integrated control system in the heat affected zone and weld temperature controllable characteristics such as non-contact welding, tiny, used in plastic welding.