Thermal cutting: Application Comparison and development of three cutting methods

The so-called thermal cutting mainly includes flame cutting, plasma cutting and laser cutting. According to the different cutting requirements and market prices, the three cutting methods currently occupy a certain market. The technical and economic comparison is as follows:

Due to the influence of air pressure, cutting nozzle height, preheating time and other factors, the overall cutting material has large deformation scale, which can not meet the needs of high-precision cutting, and the cutting speed is relatively low. At the same time, due to preheating before cutting, it takes time, which is difficult to meet the needs of unmanned operation. Plasma cutting has the characteristics of fast cutting speed and wide range. It is suitable for cutting low thickness metal plates and a variety of non-metallic materials. The maximum cutting speed can reach 10 m / min, which is 10 times of flame cutting. Underwater cutting can eliminate the noise, dust, harmful gas and arc generated during cutting, which is conducive to environmental requirements. At present, with the maturity of high-power plasma cutting technology, the cutting thickness can reach 130mm. The high-power plasma cutting using water jet technology has made the cutting quality close to the lower limit of laser cutting accuracy (± 0.2mm). Because the laser cutting machine is expensive and only suitable for cutting thin plates (usually the drilling time of thick plates is long), the cutting accuracy of fine plasma cutting machine can reach the lower limit of laser cutting, and the cutting surface quality is similar, but the cutting cost is far lower than that of laser cutting, about 1 / 3 of which, and the maximum cutting thickness can reach 12mm, so the expensive laser cutting machine is replaced by fine plasma cutting machine The cutting machine is conducive to high-speed fine cutting of medium and thin plates with large consumption in the most economical way. In addition, the combination of NC plasma cutting and automatic nesting programming software can improve the material utilization rate by 5% - 10%. If the annual cutting is 20 million tons, the annual steel consumption can be saved by 1-2 million tons, worth several billion yuan. Therefore, in the developed countries, the development trend of replacing flame cutting machine and laser cutting machine with numerical control plasma cutting machine has appeared.

China's numerical control flame cutting technology started in the mid-1980s, but the numerical control plasma cutting machine is later. Most of the numerical control plasma cutting machines are mainly economic machine tools (SCM as the core, stepping motor as the driving element). At one time, there were more than 50 domestic manufacturers engaged in CNC cutting machine manufacturing, with scattered power. Many of them were formerly welding and cutting tool factories, with poor technical foundation. Throughout the 1980s, domestic enterprises were unable to compete with foreign enterprises in terms of product structure and production scale. After entering the 1990s, some domestic companies aim at the world's advanced level and continuously develop new products of CNC cutting machines. Moreover, the main technical indicators of some products have reached the advanced level of similar foreign equipment. At the same time, with the regulatory role of market economy, the domestic manufacturers of CNC cutting machines have been adjusted to more than 20, but the overall R & D and production capacity is higher than before Significantly improved. Especially in recent years, the domestic CNC cutting industry has invested a lot of funds and R & D forces in steel pipe cutting, intersecting line cutting and other related fields and made breakthroughs. As a landmark technical achievement of CNC cutting industry, intersecting line cutting will broaden the scope of original material cutting and realize the possibility of pipe groove cutting. Earlier, similar CNC system was only owned by foreign manufacturers, and the price of a multi axis linked intersecting line cutting machine is up to RMB 1 million.

In general, CNC plasma cutting technology is a high-tech which integrates CNC technology, computer software and hardware technology, plasma cutting technology and precision machinery technology. The development of CNC cutting can completely change the equipment level of domestic hot cutting industry, reverse the current situation of low efficiency, poor quality, high labor intensity, low utilization rate of materials, and poor environment, and narrow the gap with foreign advanced countries. At the same time, the development of numerical control cutting technology can drive related fields and disciplines to reach the international advanced level.