The laser head is an important part of the fiber laser metal cutting machine, which is used to generate laser beam energy for cutting, similar to the human heart. Today, we mainly introduce the structure and type of fiber laser metal cutting head.
Fiber laser metal cutting machine head structure
The laser cutting head generally consists of a nozzle, a focusing lens, an auxiliary system, and a focus tracking detection system.
The nozzle is one of the most important parts of a fiber laser metal cutting machine. It is located at the bottom of the laser head, and the laser and high-pressure airflow are ejected through the nozzle, which is related to the cutting quality and service life of the laser cutting equipment.
The nozzle is usually coaxial with the laser cutting head and has many shapes: cylindrical, conical, zoom, and so on. Principle of nozzle selection: Its aperture must be larger than the focused beam. In other words, the laser beam cannot hit its wall when passing through the nozzle.
Large-caliber nozzles do not have strict requirements for laser beam focusing, while small-caliber nozzles have higher requirements for laser beam focusing. Therefore, it is necessary to ensure that the collimation and diameter of the laser beam perfectly match the nozzle diameter. In practical applications, since the outlet of the auxiliary gas is also in the nozzle part, it is very important to choose a suitable caliber. If the diameter is too small, the gas field of the nozzle will appear turbulent, and the nozzle will be locally deformed due to high temperature.
The higher the height between the nozzle and the sub-material, the energy loss of the laser component will not achieve the expected cutting effect. On the contrary, the blown slag easily enters the cutting head, which will not only damage the lens but also disturb the flow field and affect the focus position. However, current fiber laser head height trackers usually have a height adjustment function.
How to choose the right nozzle?
- Nozzle material
A good nozzle must have high electrical conductivity and good thermal conductivity. Generally speaking, copper nozzles are better than brass nozzles, which can ensure a good capacitance signal.
- Nozzle accuracy
A good laser head nozzle has a concentricity of 0.03mm. A high-precision nozzle not only reduces debugging but also prevents high-energy lasers from hitting the inner wall of the laser head.
- Nozzle surface oxidation treatment
The smooth surface and good anti-oxidation nozzle can effectively reduce the adhesion of the melt and prolong the service life.
The nozzle diameters are φ1.0 mm, φ1.5 mm, φ2.0 mm, φ2.5 mm, φ3.0 mm, etc. We often use two sizes: φ1.5 mm and φ2 mm.
1. Thin plates below 3mm: Use φ2mm corners to melt easily.
2. Thick plates above 3mm: Due to the large laser cutting power, the heat dissipation and cutting time are relatively long, so replacing φ2mm with φ1.5mm is unstable.
3. φ2.5mm can only be used for thick plates over 10mm.
When you choose a larger nozzle aperture, the protection of the focusing lens is worse, because the spark splash of the melt is more likely to be lifted.
The center of the nozzle and the center of the laser is one of the important factors that affect the quality of laser cutting. The greater the thickness of the workpiece, the greater the factor. So you should adjust to the center of the laser to get better cutting quality.
The focusing lens is located directly above the nozzle. Its main function is to focus the beam to obtain an energy-intensive spot. Focusing mirrors can be divided into two types: transmissive and reflective.
Among them, the transmissive laser head generally uses a projection mirror, and the reflective laser head generally uses a reflective mirror. There are many types of lens materials, and zinc selenide has become the first choice for lens materials with ultra-high light transmittance and the lowest light absorption.
Generally speaking, the smaller the focal length of the focusing lens, the smaller the diameter of the focused spot (the denser the energy from the focal point), and the shallower the focal depth. (The depth of focus refers to the distance between two light spots with a 5% change in diameter on both sides of the focal point, which is also called the effective cutting range in cutting.
When cutting thick plates, shallow depth of focus will seriously affect the cutting quality, resulting in burrs and burrs. Moreover, the shallow depth of focus will shorten the distance between the fiber cutting head and the plate, and the molten slag will easily penetrate the laser head, which is not effective. Therefore, we should try to use a suitable focal length for post-editing.
When the thickness of the sub-material is larger, the weak state of the spot energy can be alleviated by using a larger focal length and increasing the laser power. When the thickness of the secondary material is small, a smaller focal length can be used to achieve high-speed cutting.
How to choose the right focus lens?
The price of protective lenses on the market ranges from tens of yuan to hundreds of yuan, and the quality is also uneven. Of course, it is not uncommon to see low-quality lenses. If the lens is not selected properly, it will cause large laser loss, frequent damage to the protective lens, unstable product quality, and serious losses to the enterprise. Therefore, it is very important to choose the right protective lens.
- The size matching is easy to understand.
- According to different laser power and cost, K9 and quartz can be selected. In the actual application process, professional manufacturers divide these two materials into several grades, and customers can choose the corresponding specifications according to actual needs.
- Coating, laser anti-reflection coating, coating process parameters are different according to the use environment.
The auxiliary system includes a water cooling system, auxiliary gas, and protective gas.
The water cooling system is to protect the laser cutting head. Cooling is performed without affecting processing efficiency and quality. Everyone knows the common uses of auxiliary gases, so I won’t repeat them here, but why do different plates choose different gases?
In fact, the heat generated in the cutting process is not only the energy of the laser beam but also the additional energy brought by the auxiliary gas. When cutting active metals, inert gas is usually used to prevent additional heat from affecting the cutting effect. Instead, use reactive gas to increase the cutting heat.
In addition, the auxiliary air pressure for high-speed cutting of thin plates can be set to a high pressure (100-300 kPa) that matches the cutting speed. If cutting thick plates at low speed, low pressure is required to prevent splashing.
Focus tracking detection system
Focus tracking systems are generally designed to ensure a stable focus. According to different requirements, detection devices with different functions are installed on the cutting head to keep the cutting error rate low.
The focus tracking system is composed of a focused fiber laser cutting head and a tracking sensor system. When the shape of the laser cutting head changes and the surface is uneven, the sensor automatically detects the change, and automatically adjusts the height according to the change, so that the distance between the laser cutting head and the surface of the workpiece is always consistent.
According to different sensor elements, tracking systems are mainly divided into capacitive sensor tracking systems, also called non-contact tracking systems, and inductive sensor tracking systems also called contact tracking systems.
How to clean and maintain the fiber laser lens?
Due to the characteristics of the laser cutting process, regular maintenance of the lens is required. It is recommended to perform a weak cleaning of the protective lens. The collimator and focusing lens need to be cleaned every 2 to 3 months. In order to facilitate the maintenance of the protective lens, the protective lens holder adopts a drawer-type structure.
Lens cleaning tools: dustproof gloves or finger cots, polyester-cotton swabs, ethanol, rubber air blower. Cleaning instructions:
- Wear finger cots on the left thumb and index finger;
- Spray ethanol on the polyester-cotton swab;
- Gently hold the sliding edge of the lens with the thumb and index finger of your left hand. (Note: Avoid touching the surface of the lens with your fingertips)
- Place the lens in front of your eyes and hold the polyester-cotton swab with your right hand. Gently wipe the lens in one direction, from bottom to top or from left to right, (do not wipe back and forth to avoid secondary pollution of the lens), and blow the surface of the lens with rubber. Clean both sides. After cleaning, make sure that there are no residues: detergent, absorbent cotton, foreign matter, and impurities.
Removal and installation of laser cutting head
Material needed: optical fiber protective sleeve
- Disassembly of the laser cutting head
Before replacing the laser cutting head lens, you need to remove the laser cutting head first. The unloading of the laser cutting head cannot directly twist the optical cable, and the cutting head needs to be removed first. The drag chain above the laser head needs to be disassembled in advance, and then use a screwdriver to loosen the screws of the cutting head. After loosening, remove the water pipe, and finally remove the optical cable. When pulling out the optical fiber, you need to place the laser head horizontally and release the lock. Buckle, use the pre-prepared optical fiber protective cover. When pulling out the optical fiber, quickly cover the optical fiber head with the optical fiber protective sleeve while keeping it level.
- Install the laser cutting head
The installation and removal of the laser cutting head are similar. Be sure to keep the cutting head level, remove the optical cable protective cover, quickly and accurately insert the docking hole, tighten the knob, but the laser cutting head is back in place, and tighten the screws. Connect other pipes, and the installation is complete. The inlet pipe is connected to one side of the water inlet of the QBH head, the outlet pipe is connected to the bottom of the other side, and the bottom is connected to the loop, and the water returns to the water tank.
The ultimate guide to choosing a fiber laser metal cutting machine
When choosing to buy a fiber laser metal cutting machine, in addition to the laser cutting head, what are the main points we need? The following FORSUN CNC will introduce how to choose a suitable fiber laser cutter.
The scope of materials and business requirements handled by the company
First, we must clearly consider the business space, the thickness of the cutting elements, which elements must be cut, and other factors. After completing all these factors, select the size of the equipment and facilities to be obtained. Therefore, the manufacturer can customize the function of the workbench according to the customer’s requirements.
Choose a well-known integrator in the industry
Understand the strength, machine parameters, product quality, and performance of laser cutting machines. Once you pop out, the laser cutter is an in-depth kit series. You should be careful when choosing the right integrator, they have the strength and price discount in the early stage of speech and proofing and provide equipment training. FORSUN CNC is a professional fiber laser metal cutting machine supplier. If you want to have any questions about purchasing a fiber laser cutting machine, please feel free to contact us and we will recommend the most suitable machine for you.
The backbone of the laser cutting machine
The metal laser cutting machine has some key components, we should know everything about it before buying. Such as laser generator, laser cutting head, servo motor, guide rail, water tank, etc. Because these parts directly affect the cutting speed and accuracy of the laser cutting machine.
Choose a brand with excellent after-sales service
The after-sales service of each manufacturer is very different. The span of the warranty is also uneven. FORSUN CNC provides customers with daily maintenance programs, machines, and laser software. Our highly skilled professionals train the machine operation and software when customers install it. Our timely and immediate 24×7 service makes us a leader in the laser industry.
In short, buying a laser cutting machine for a business can be a major investment, so by choosing the right integrator and generating more revenue from it, you can save a lot. However, a suitable laser cutting machine can bring high production efficiency and save costs. If it can bring benefits to the enterprise, then the first investment is worth it.
Learn more: How To Choose A Fiber Laser Cutting Machine?
I believe that through the above guidelines, you can now narrow the selection of laser cutting machine suppliers to two to three sources. If you have any other questions, please feel free to leave us a message. As a professional fiber laser cutting machine supplier, FORSUN CNC has more than 10 years of industry experience. We will provide you with free professional guidance and professional customized solutions.