Fiber laser cutting machine special process effect on cutting quality
Through a large number of experimental research on laser cutting machine laser cutting processing quality, from the special process to analyze perforation technology, wire set and corner disposed the special process of the influence of cutting quality and processing efficiency.
As for sheet metal processing, laser cutting technology can save the cost of expensive tooling and shorten the processing cycle, which has obvious advantages for new product development, single piece small batch production and multi variety turn production. The experience of using in cutting applications based on the main factors influence the cutting quality of the introduction of L technology, wear alone lead set and corner set three aspects of the influence of process parameters on cutting quality.
1. perforation technology
Any kind of thermal cutting technology (such as laser processing, plasma processing, flame cutting, etc.), except a few cases can start from the edge of the plates, usually must be pre wear a hole in the metal plate, and then the subsequent processing. Perforation quality directly affects the quality of cutting contour, especially small outline contour size close to the thickness of the plate; secondly, wear alone L the length of time also directly affects the machining efficiency, so the perforation technology is the key technology of laser cutting processing. There are three kinds of common perforation methods.
1.1 blasting perforation
As shown in Figure 1, also called the direct blasting perforation perforation (CW), the working principle of continuous laser beam, somewhere in the surface of the material, the formation of a pit, then according to the laser beam and the coaxial auxiliary gas, forming a single L type, according to the equipment and materials on poor formation of perforation gap, the final completion of the entire process of blasting wear alone L.
The size of this gap is generated in the process of perforation with the thickness of the plate is proportional to the. Processing of thicker materials, the perforation of the gap is wide, material waste caused by the greater. The advantages of blasting perforation can greatly improve wear alone L time, thereby improving the production efficiency, the disadvantage is in perforation, will produce a large amount of molten metal to spray phenomenon, easy pollution of fiber laser cutting head protection lens, and plate cutting holes (diameter < thickness), due to wear out this L diameter may exceed the required cutting contour diameter, lead scrap.
1.2 pulse perforation
Pulsed perforation is performed by pulsed laser with the most powerful peak value in the laser beam. The power of the pulsed laser beam can reach about 2.5 times of the rated power, and the material can be melted and even vaporized. The use of pulsed laser is gradually working principle deeply, for processing thick materials, does not affect the cutting effect, but the cutting speed is slow, so the processing quality, is higher than that of blasting perforation, as shown in figure 2. When the carbon steel plate thickness is above 10mm, the use of pulse
The processing time of perforation will increase sharply. Theoretically, it is possible to change the conditions of the perforation, such as focal length, nozzle position, gas pressure and so on. But in fact, due to the time is too short, it is unlikely to change the above. It is mainly used in actual production
The method of changing the laser average power. There are three methods: 1. Changing pulse duty ratio; changing pulse frequency; changing pulse duty ratio and frequency at the same time. The results show that the best effect of perforation quality is high and stable.
1.3 zoom punch
The principle of zoom perforation is cutting head is installed above the variable radius of curvature of the lens (VRM), the relative position change of curvature radius of the lens in a timely manner in the process of perforation so as to change the focus, to save time and improve the efficiency of perforation perforation and the stability of the. Perforation of a large number of experimental data shows that the wear alone L way than the efficiency of the above two modes can be increased by more than 20%. The disadvantage is that because of the frequent change of the radius of curvature, the lens is easy to be damaged for a long time, and the manufacturing cost of the lens is relatively high, so it can not be used in large quantities.
In summary, the laser cutting hole process is no more than one or more combinations, which need to be selected according to the actual situation. Considering the effect of heat treatment on cutting, it is necessary to use pre piercing technology or interval perforation technology to cut products so as to produce high-quality products.
2. lead set
In the normal cutting process, usually adopts Cw mode wear alone L. This type of punching time is short, but as mentioned above, this method produces a hole larger than the pulse punch. Therefore, from outside the perforated position usually on contour. The cut line between the hole and the actual contour is called the lead-in line, and the cut line at the end is called the lead line. The setting of lead wire is also important to cutting quality. The wire setting is mainly divided into two aspects: lead length and lead wire type.
2.1 lead length
Due to wear alone L process will produce a large amount of heat, before cutting the actual contour as far as possible is the key to radiate heat, especially important in cutting the inner contour of small, improper handling can lead to cutting. The test results show that the length of the wire depends on the thickness of the plate and the diameter of the hole. Table 2 is the reference data sheet of the ML-3015F model.
2.2 lead type
Laser cutting processing for thermal processing type, in the process of cutting power and the size of the auxiliary gas flow stability, nozzle xinjiuchengdu even the machine tool movement performance will affect the cutting quality and cutting precision, from the theoretical analysis of the introduction of any way can meet the cutting requirements, in order to make up for the above factors influence on the cutting. Automatic programming software can be set up in various types of wire to avoid cutting defects. The type of lead has straight line, arc, straight line + arc, straight line and so on. At the same time, it can set any line and arc at any angle.
3. corner setting
In cutting carbon steel plate, due to the influence of machine tool motion shaft of the reducer and auxiliary gas flow at the corner and will lead to different degrees of burns appear at right angles; the stainless steel plate cutting, if not processing, will appear at the corner of a relatively large cutting burr. Therefore, it is necessary to optimize the cutting path and avoid the burn and burr by chamfer or corner setting.
Setting chamfer radius to the corner can not only reduce burr, but also make the dynamic performance of the axis move better, and reduce the heat affected zone. The optimal radius R= plate thickness, 10, but not less than 1mm. For users with special requirements, it is not allowed to fillet processing at the corner, at this time need to use the corner settings as shown in Figure 4 (angle treatment) mode to achieve the most ideal cutting effect.
Laser cutting is a very complex processing technology, there are many factors affecting the quality of cutting and processing efficiency. In this paper, the cutting method, wire setting and corner processing are used to analyze the factors that affect the cutting quality. A large number of cutting processing shows that the processing of the above settings, to improve the quality of cutting a great help.
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