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Views:0 Author:hu Publish Time: 2021-08-24 Origin:dapeng
Principle classification of laser cleaning
There are various cleaning methods for traditional cleaning industrial equipment, most of which are cleaned by chemical agents and mechanical methods. As my country’s environmental protection laws and regulations are becoming stricter and people’s awareness of environmental protection and safety is increasing, the types of chemicals that can be used in industrial cleaning will become less and less. How to find a cleaner and non-damaging cleaning method is a problem we have to consider. The laser cleaning has the characteristics of non-grinding, non-contact, low thermal effect and suitable for objects of various materials, and is considered to be the most reliable and effective solution.
Among the contaminants on the surface of the workpiece, the bonding between the surface of the workpiece and the surface is mainly due to the following forces: covalent bonds, double dipoles, capillary action, hydrogen bonds, adsorption forces and electrostatic forces. Among them, capillary force, adsorption force and electrostatic force are the most difficult to destroy, and laser cleaning technology is to overcome these forces.
These adsorption forces are much larger than gravity (several orders of magnitude) and are related to the particle diameter d. The adsorption force shows a slow linear decay trend as the particle radius decreases, while the particle mass m is proportional to the third power of the diameter. , According to Newton's law, F=ma, when the particle size becomes smaller, the acceleration provided by the adsorption force increases rapidly. Therefore, the smaller the particle size, the greater the acceleration required to remove it. This is why it is difficult for conventional cleaning techniques to remove surface attachments on objects with small diameters. Due to the complex composition and structure of the attachments on the surface of the object, the mechanism by which the laser acts on it is also different. The most commonly used theoretical models for explaining this are as follows:
1. The laser generated by the phosgenation/photolysis laser can achieve a high concentration of energy through the condensing of the optical system. The focused laser beam can generate thousands of degrees or even tens of thousands of degrees near the focal point, making the surface of the object attached. The object vaporizes or decomposes instantly.
2. Optical peeling makes the attachments on the surface of the object heat and expand through the action of the laser. When the expansion force of the attachments on the surface of the object is greater than the adsorption force between it and the substrate, the attachments on the surface of the object will be separated from the surface of the object.
3. Optical vibration uses higher frequency and power pulsed laser to impact the surface of the object, generating ultrasonic waves on the surface of the object. The ultrasonic waves return after impacting the hard surface of the lower layer, and interfere with the incident sound waves, thereby generating high-energy resonance waves and making the dirt small. This cleaning method can be used when bursting, crushing, or detaching from the surface of the matrix material, when the absorption coefficient of the laser beam between the object and the surface attachment is not much different, or the surface attachment will produce toxic substances after heating.
At present, there is no uniform standard for the structure of laser cleaning equipment. It needs to be determined according to the actual cleaning method, the type of substrate and dirt, and the effect of cleaning requirements. However, they are still roughly the same in some basic structures. , Mainly including lasers, mobile platforms, real-time monitoring systems, semi/automatic control operating systems and other auxiliary systems.
Prospects of laser cleaning technology: The emergence of laser cleaning technology has opened up a new field of laser technology in industrial applications. Its development in the fields of microelectronics, construction, nuclear power plants, automobile manufacturing, medical care, and cultural relics protection is in the ascendant, and the application market has a bright future. .