First, Cnc fiber laser cutting machine cutting and perforating technology
Any thermal cutting technique, except in rare cases where the edge of the plate may be started, generally requires a small hole to be pierced in the plate. Before the laser stamping compound machine is to use the punch out of a hole, and then use the laser from the hole began to cut. There are two basic methods of perforation for laser cutting machines Fiber laser cutting machine without stamping devices:
Pulse perforation - the use of peak power of the pulse laser to melt or vaporize a small amount of material, commonly used air or nitrogen as an auxiliary gas, in order to reduce the exothermic oxidation of the hole expansion, gas pressure is smaller than the oxygen pressure when cutting. Each pulsed laser produces only a small jet of particles, gradually penetrating, so the thick plate perforation time takes a few seconds. As soon as the perforation is complete, the auxiliary gas is replaced with oxygen for the cutting. In this way, the diameter of perforation is smaller, and the quality of perforation is better than that of blasting perforation. The laser used for this purpose should not only have a high output power; More important is the time and space characteristics of the beam, in addition, pulse perforation also needs a more reliable gas path control system, in order to achieve the type of gas, gas pressure switch and perforation time control.
Blast perforation - the material is hit by a continuous laser to form a crater in the center, which is then quickly removed by a stream of oxygen coaxial with the laser beam to form a hole. The size of the general hole is related to the thickness of the plate, the average diameter of the blasting hole is half of the plate thickness, so the hole diameter of the thick plate blasting hole is larger, and it is not round, and it is not suitable for the use of parts with higher processing accuracy requirements, but can only be used for waste. In addition, because the oxygen pressure used for perforation is the same as that used for cutting, the splash is larger.
Two, cutting hole deformation analysis
This is because the machine tool in the processing hole is not to take the way of blasting perforation, but the way of pulse perforation, which makes the laser energy in a very small area is too concentrated, the non-processing area is also burnt, resulting in the deformation of the hole, affecting the processing quality. At this time, we should change the pulse piercing mode into the blasting piercing mode in the processing procedure to solve the problem. On the contrary, for the laser cutting machine with small power, pulse perforation should be adopted to obtain better surface finish.
Three, when cutting low carbon steel abnormal spark
This situation will affect the parts of the cutting section finish processing quality. At this time, in the case of other parameters are normal, the following circumstances should be considered: the loss of the laser head nozzle NOZZEL, the nozzle should be replaced in time. In the case of no new nozzle replacement, the cutting gas pressure should be increased; The thread at the connection between nozzle and laser head is loose. At this point, the cutting should be suspended immediately, check the connection state of the laser head, and re - threaded.
Four, the analysis of laser not completely cut through state
After analysis, it can be found that the following conditions are the main conditions of processing instability: the choice of laser nozzle and processing plate thickness does not match; Laser cutting line speed is too fast, the need to reduce the line speed operation control; The nozzle induction is not allowed to lead to the laser focus position error is too large, it is necessary to re-test the nozzle induction data, especially when cutting aluminum is most likely to occur.
Five, laser cutting of low carbon steel, the workpiece burr
According to the laser cutting work and design principle, analysis of the following reasons are caused by the workpiece burr: the upper and lower position of the laser focus is not correct, the need to do the focus position test, according to the focus of the offset adjustment; Laser output power is not enough, need to check whether the laser generator is working normally, if normal, then observe the output value of the laser control button is correct, to adjust; Cutting line speed is too slow, the need to increase the line speed in operation control; The purity of cutting gas is not enough, the need to provide high quality cutting gas; Laser focus offset, need to do focus position test, according to the focus of the offset to adjust; Machine tool running time is too long appear instability, at this time need to shut down restart.