Nowadays, with the rapid development of laser cutting machine manufacturing technology and the continuous improvement of numerical control technology, the market application of optical fiber laser processing equipment in metal sheet cutting is rapidly applied. With the rapid development of equipment and technology update, many users encounter many problems in thick plate cutting. According to the market feedback information, the thickness of sheet metal, the cutting quality and the selling price of cutting equipment subdivide the market application group of sheet metal processing and manufacturing, especially the small and medium-sized enterprise users in this field urgently need a complete set of high-power fiber laser cutting machine with good cutting quality and the thickness range of metal sheet metal. What are the difficulties of laser cutting machine in cutting thick plates? REDSAIL laser editor will share with you.
1. The slit is too narrow, resulting in increased heat loss. The reduction of the cutting speed increases the heat loss in the cutting area. The main form of heat loss is heat conduction. The greater the thickness, the greater the heat conduction loss and the lower the cutting speed. The material removal at the bottom of the notch becomes inconsistent, although the laser penetrates the thick plate, and a large amount of slag adheres to the bottom. The formation of slag hanging is caused by the low average cutting temperature at the bottom of the cut. The low temperature is also due to the large energy loss. In this case, the quality of the cut is usually not high.
2. The diameter of optical fiber laser spot is small and the focal length depth is limited. Although the fiber laser cutting machine can maintain a high laser power density in the cutting depth when cutting medium and thick metal plates, it is not conducive to cutting and slag removal due to the small beam diameter and fine cutting seam. This puts forward higher requirements for the mode and beam collimation shaping and range of the fiber laser, and also brings greater difficulties for the process quality of the fiber laser cutting medium and thick metal plates.
3. Effect and influence of auxiliary gas quality and air pressure. Take oxygen as an example; Oxygen plays an important role in cutting medium and thick carbon steel plates with fiber laser. The laser enters the workpiece surface to form a small hole. When the laser beam moves along the cutting direction, there will be oxidized melt around the small hole and the cutting seam. The purity and pressure of oxygen have a great impact on laser cutting. Oxygen with many impurities and inappropriate air pressure cannot provide enough energy to form high fluidity melt at the bottom of the incision, thus reducing the cutting quality and cutting speed. By measuring the quality and pressure of the auxiliary gas at different slit positions, it is found that the narrower the slit, the worse the effect of the auxiliary gas, and the harder it is to maintain the cutting quality. Therefore, it is very important to ensure the proper slit width, the auxiliary gas quality and the air pressure control.
4. The difference of geometry makes the cutting quality of inflection point decrease. When laser cutting thick plates, the inclination of the melting front becomes prominent, which will lead to the reduction of the laser absorption coefficient of the material, and then increase the cutting power and reduce the cutting speed to ensure the cutting quality. Laser cutting machine will be more widely used in cutting field because of its high spot conversion rate, high cutting accuracy, flexible processing ability, good cutting quality and adaptability.