The Fiber laser cutting machine will encounter some problems when processing medium and heavy plates. How to solve it? As an advanced material cutting method, laser cutting machine processing is more and more accepted by sheet metal producers due to the advantages of less material waste, obvious cost effect in large-scale production, and strong adaptability to the processed objects. Today, China's crude steel output is not only the world's first, but also exceeds 50% of global output. This article will talk about the problems often encountered in the processing of medium and heavy plates by laser cutting machines
1. Perforation of thick carbon steel plate
Perforation time accounts for a large proportion in the processing of thick plates. Various laser manufacturers have developed rapid perforation technology. The representative is high-energy perforation (explosion hole). The advantage of this method is fast speed (1 second, t16mm For example-the same below), the defect is that it not only affects the processing of small shapes, the huge energy injected during perforation increases the temperature of the sheet and affects the subsequent overall cutting process. If the low-power pulse is used for perforation, the time is very long (12 seconds), which will lead to a reduction in cutting efficiency and an increase in unit cost.
2. Cutting surface quality problem
When cutting medium and heavy plates, we often encounter cutting sections. Such cutting not only questioned the quality of the finished product, but also accompanied by over-burning and serious sticky slag, so that it can not reflect the value of the high-priced laser processing machine.
3. The stability of the whole board processing
In the whole board processing of domestic steel products, the phenomenon of poor local processing often occurs. This phenomenon is sometimes very random, even when the processing machine is in good condition.
The solution of laser processing medium and heavy plate is as follows:
1. High Peak Perforation (HPP) scheme
Using high peak pulse laser with a small duty cycle, supplemented by non-fuel sprayed on the surface of the material to remove the attachment at the edge of the opening, controlling the reasonable frequency of the pulse while cooling and perforating. It is characterized by a relatively long time (3 seconds) for the relatively deep hole, but the hole diameter is small (about φ4mm) and there are no attachments at the edge of the hole and the heat input is low, which is convenient for the subsequent normal cutting processing, compared with ordinary perforation Then the efficiency is increased by 4 times.
2. Improvement plan for cutting section
For carbon steel, the important factor to improve the cutting section is to control the heat input to the plate and ensure that the laser irradiated part is fully burned. For stainless steel, the important factors for improving the cutting section are the improvement of the beam (improving the depth of focus) and the effective use of auxiliary gas. The bright surface cutting technology is to improve the results obtained by the oscillator and the nozzle.
3. Plan to ensure processing stability
Metal Sheet laser cutting machine processing problem solution, currently in order to increase the processing speed of the processing machine, the laser machine mostly uses the structure commonly known as the flying optical path, that is, the material tray does not move and the processing head moves in the form of the entire processing area. In order to compensate for the change in the relative position of the processing head and the light source, each manufacturer also tries to ensure the consistency of the light spot within the processing range. The use of variable curvature refractors is the generally selected method. Although this method has a simple structure, it will change the depth of focus, which makes it difficult to cut the medium and thick plates that are extremely sensitive to the depth of focus (both the spot and the depth of focus must be maintained). Using the equal-length optical path method (the optical transmission path between the light source and the processing head is of equal length in the processable range) can avoid the change of the depth of focus, thereby keeping the spot and the depth of focus consistent. In addition, the emphasis on heat input can control the heat accumulated in the plate, which can better solve the stability problem.