Portable laser welding equipment has become a revolutionary product in the laser application market in recent years, quickly emerging as a growth point of the green laser industry.
Since 2018, the compound annual growth rate of portable laser welding has exceeded 100%, indicating unprecedented market demand. The number of portable laser welding machine manufacturers is expected to reach 100 in 2020 and 500 manufacturers of various types of portable laser equipment integration in 2021, demonstrating explosive growth.
For portable laser welding machines, the welding head that connects the usage scene and outputs laser energy is an essential component. In the welding head, the optical part is a critical element that plays a vital role in the welding process.
The basic optical principle of the portable welding head consists of three components: beam collimation, beam oscillation and beam focusing, as shown in the figure below.
After the QBH emits a laser beam, it passes through a collimating mirror and becomes parallel light. It is then reflected by the galvanometer and directed towards the focusing lens. Finally, the laser beam is focused on the surface of the part.
Beam collimation
The light emitted by the QBH optical fiber originates from a point source and has a certain angle of divergence. As it spreads, it spreads in a conical shape, like turning on a flashlight and striking a match in the darkness.
The purpose of the collimator is to convert divergent light into parallel light and ensure that it travels in a straight line without deviation. Furthermore, the beam waist radius is controlled to restrict it to the narrow optical path of the welding head.
Beam swing
In manual welding, the purpose of beam balancing is to improve the adaptability of the weld gap.
Due to the small size of the focused spot, it can be challenging to follow the weld track while holding it. Additionally, it can also be challenging to cover the weld with a large gap.
To address these challenges, the beam is arranged in a straight line up to 3.0 mm wide. This allows the operator to conveniently align and cover the laser with the weld.
The beam oscillation is achieved by a vibrating lens that rapidly deflects back and forth, driven by a motor. This effectively changes the path of the laser beam.
The basic principle is shown in the figure below:
According to the basic law of reflection, the angle of reflection is equal to the angle of incidence.
When the galvanometer is positioned at angle 1, light is reflected along path 1 and focused on point 1. Similarly, when it is positioned at angle 2, light is reflected along path 2 and focused on point 2.
If the galvanometer oscillates between angles 1 and 2, the focused light spot will move back and forth between points 1 and 2. When the speed of movement is high enough, it will appear as a straight line.
The length of this straight line is known as the “oscillation width”, while the frequency of deflection is known as the “oscillation frequency”.
The air-cooled intelligent portable welder has an adjustable swing width of 0~5mm and an adjustable swing frequency of 0~300Hz.
Beam focusing
The galvanometer reflects a parallel beam of light that converges to a small point after passing through the focusing lens. The small dot then impacts the surface of the part.
The purpose of the focusing lens is to concentrate the parallel beams, forming a small point of light. This allows the production of superdensity of energy.
Role of protective lenses
During manual welding, smoke and dust are produced, which can potentially damage the focusing lens. Therefore, it is essential to safeguard the lens to ensure its functionality and longevity, providing adequate isolation and protection.
Conclusion
Protective lenses are considered consumables, so it is important to regularly check their condition. The frequency of these checks must be determined based on the level of intensity of the service and the environment in which the equipment is being used.
