Fiber laser cutting machine has many advantages, such as high cutting accuracy, narrow cutting seam, smooth cutting surface, and high efficiency. The use of optical fiber laser cutting machine has significant advantages in terms of safety and environmental protection. In the future development trend, the use of fiber laser cutting machine will become the mainstream.
Cutting speed
Fast cutting speed is one of the advantages of laser cutting, but that doesn't mean that faster cutting speed shows better cutting quality. Under the condition of a certain laser power, it is necessary to select an appropriate cutting speed according to the cutting plate to make the cutting surface beautiful and obtain high-quality cutting work-piece. The following methods can be used to determine whether the cutting speed is appropriate, and then adjust the cutting speed.
1. Observe the cutting spark. When the cutting speed is appropriate, the cutting spark will spread evenly from top to bottom; When the cutting speed is too fast, the cutting spark will tilt; When the cutting speed is too slow, the cutting sparks will gather together, not diffuse and few.
2. Observe the cutting plate. When the cutting speed is appropriate, the section presents a relatively stable line, and there is no slag in the lower half. If the cutting speed is too fast, it may not be able to cut through and sparks may be sprayed randomly; Some areas can be cut through, while others cannot; The cutting section is a twill road, and slag is generated in the lower part. If the cutting speed is too slow, it will cause over melting, rough cutting section and wider cutting seam.
Nozzle and nozzle height
The nozzle is used as the beam and auxiliary gas channel. The shape, aperture and height of the nozzle will affect the cutting effect. The nozzle mainly controls the gas diffusion area and size, thus controlling the cutting quality; Prevent slag and other sundries from bouncing up and passing through the nozzle to pollute the lens. Generally speaking, the nozzle with small diameter is selected for small defocusing amount when cutting thin plates; The large aperture nozzle is selected because of the large slit and light spot required for cutting thick plates.
The nozzle is divided into single-layer and double-layer. The single-layer laser nozzle is used for melting and cutting, that is, nitrogen is used as auxiliary gas for metal laser cutting, mainly the stainless steel and aluminum plates cutting; Double layer laser nozzle is generally used for oxidation cutting, that is, oxygen is used as auxiliary gas to cut carbon steel.
The nozzle height is the distance between the nozzle outlet and the work-piece surface. When cutting, this height is generally set at 0.3mm-0.8mm. If it is too low, the nozzle will easily collide with the work-piece surface. If it is too high, the concentration and pressure of auxiliary gas will be reduced, resulting in a decline in cutting quality. During perforation, the nozzle height can be properly raised to prevent the generated slag from returning to the lens.
Focus position
After checking the actual zero focus of cutting, in the actual cutting process, we need to set the appropriate focus position to obtain the cutting workpiece with better cutting effect:
1. Zero focus: the focus is on the surface of the work-piece, which is suitable for cutting thin plates.
2. Negative focus: the focus is under the surface of the work-piece, usually at 1/2-2/3 of the thickness of the work-piece, so the range of the smooth surface is large, and the slit will be wider than the zero focus.
3. Positive focus: the focus is on the upper surface of the work-piece, which is generally applicable to the cutting of thick plate carbon steel (thick plate requires large kerf, and negative focus will lead to carbon steel burning).
Protection gas pressure
The size of the auxiliary gas pressure also affects the cutting effect of the fiber laser cutting machine. Adjusting the air pressure can also improve the cutting effect.
Insufficient air pressure: when the air pressure is insufficient, the slag generated by cutting cannot be removed, which is difficult to penetrate, resulting in slag generated on the cutting surface; The cutting speed cannot be increased, which affects the cutting efficiency. In general, when cutting thin plates at high speed, high air pressure is required to prevent slag on the back of the cutting seam; When the material is thicker or the cutting speed is slower, the air pressure can be appropriately reduced.
Too high air pressure: increasing the air pressure can improve the cutting speed to a certain extent, but excessive air pressure will reduce the cutting speed instead. The reason is that under high pressure, too fast gas flow will enhance the cooling effect, and even interfere with the focusing of beam energy, leading to the decline of cutting quality and efficiency. At the same time, when the air pressure is too high, the cutting surface will be thicker and the kerf will be wider.
Summary
Excellent metal laser cutting equipment has been selected and pre cutting inspection has been done. The process parameters of laser cutting must be adjusted according to the actual situation during cutting, and the most appropriate cutting parameters should be selected according to the actual situation in specific applications. Every time we optimize the cutting process in production is also an important means to maintain long-term stability and leadership.
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Process Optimization of High Quality Cutting
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