On cutting and piercing technology

Talking about cutting and piercing technology

any kind of thermal cutting technology, except for a few cases, it can start from the edge of the board, generally must wear a small hole in the board. Previously, a hole was punched out with a punch on the laser stamping compound machine, and then cut with a laser from the small hole. For laser cutting machines without punching devices, there are two basic methods of perforation:

blasting the perforated material forms a pit in the center after being irradiated by continuous laser, and then the molten material is quickly removed by the oxygen flow coaxial with the laser beam to form a hole. Generally, the size of the hole is related to the thickness of the plate. The average diameter of the blasting hole is half of the thickness of the plate. Therefore, the hole diameter of the blasting hole for the thicker plate is large and not round, so it is not suitable to be used on parts with high processing accuracy requirements, but only on waste materials. In addition, because the oxygen pressure used for perforation is the same as that used for cutting, the splash is large

pulse perforation uses a pulse laser with peak power to melt or vaporize a small amount of materials. Air or nitrogen is often used as an auxiliary gas to reduce the hole expansion due to exothermic oxidation. The gas pressure is smaller than the oxygen pressure during cutting. Each pulse laser only produces a small particle jet, which gradually deepens, so the perforation time of the thick plate takes a few seconds. Once the perforation is completed, immediately replace the auxiliary gas with oxygen for cutting. In this way, the perforation diameter is smaller, and its perforation quality is better than that of explosion fatigue testing machine. It mainly tests the physical properties of raw materials, finished products and semi-finished products. Therefore, the laser used should not only have high output power; More importantly, the temporal and spatial characteristics of the beam, so the general cross flow CO2 laser can not meet the requirements of laser cutting. In addition, the reflex biological plasticizer used in pulse perforating Geon bio uses soybean as raw material, and a more reliable gas path control system is also required to realize the switching of gas type, gas pressure and the control of perforation time

in the case of using this energy of pulse perforation to evaluate the anti pendulum impact energy value of thin film samples, in order to obtain high-quality cuts, attention should be paid to the transition technology from pulse perforation when the workpiece is stationary to constant speed continuous cutting of the workpiece. Theoretically, the cutting conditions of the acceleration section can usually be changed, such as focal length, nozzle position, gas pressure, etc., but in fact, it is unlikely to change the above conditions due to the short time. In industrial production, it is more realistic to change the average power of laser. The specific method is to change the pulse width; To change the pulse, we should constantly summarize, analyze and revise the pulse frequency in actual operation; Change the pulse width and frequency at the same time. The actual results show that the third is the best

2. Analysis of the deformation of cutting and processing small holes (small diameter and plate thickness)

this is because the machine tool (only for high-power laser cutting machine) does not adopt the method of blasting perforation when processing small holes, but uses the method of pulse perforation (soft puncture), which makes the laser energy too concentrated in a very small area, scorching the non processing area, causing hole deformation and affecting the processing quality. At this time, we should change the pulse perforation (soft puncture) mode to blasting perforation (ordinary puncture) mode in the processing program to solve it. For the laser cutting machine with small power, on the contrary, pulse perforation should be adopted in the small hole processing to obtain a better surface finish

source: Fuzhou Bolima Precision Machinery Co., Ltd