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大功率激光切割加工关键工艺参数有哪些?

2018-05-09 15:05:06 常州亿创钣金加工厂 阅读

大功率激光切割技术是融合了激光光学、电子、机械、工艺和材料等学科的复合型先进制造技术。激光切割过程复杂,影响因素多,包括激光器输出功率、切割速度、离焦量及切割材料性能等。若工艺参数选取不当,切割质量就会受很大影响,如切割面粗糙,断面出现缺口或背面附着沾渣等。

High power laser cutting technology is a combination of laser optics, electronics, machinery, technology and materials and other disciplines of advanced manufacturing technology. Laser cutting process is complex and has many influencing factors, including laser output power, cutting speed, defocus volume and cutting material performance. If the process parameters are not selected properly, the cutting quality will be greatly affected, such as rough cutting surface, notch on the cross section or slag sticking on the back.

切割速度

切割速度一般是在速度的上下限内选择较低的值,速度过大、过小都会影响切割质量导致挂渣甚至是切不透。

切割速度过低时,激光能量密度过大,热影响区变大,会导致挂渣增多,切缝宽且粗糙。切割速度过高时激光能量密度小,有可能切不透。

切口垂直度和挂渣高度对速度参数最敏感,其次是切口宽度和表面粗糙度。

Cutting speed

Cutting speed generally selects a lower value in the upper and lower limits of speed. Too much speed and too little will affect the quality of cutting, resulting in slag sticking or even imperfection.

When the cutting speed is too low, the laser energy density is too large and the heat affected zone will increase. When the cutting speed is too high, the laser energy density is small, and it may not be able to cut through.

The verticality and slag height are most sensitive to velocity parameters, followed by notch width and surface roughness.

可提高切割速度操作包括:

●提高功率

●改变光束模式

●减小聚焦光斑大小(如采用短焦距透鏡)

It can improve the cutting speed operation including:

Increase power

Change the beam mode

Reduce the size of focus spot (such as short focal length lens).

焦点位置

激光束聚光后光斑大小与透镜较长成正比。光束经短焦长透镜聚焦后光斑尺寸很小,焦点处功率密度很高,对材料切割很有利;但它的不利之外是焦深很短,调节余量很小,一般比较适用于高速切割薄材。对于厚工件,由于长焦长透镜有较宽焦深,只要具有足够功率密度,用来对它切割比较合适。由于焦点处功率密度最高,在大多数情况下,切割时,焦点位置刚处于工件表面,或稍在工件表面之下。确保焦点与工件相对位置恒定是获得稳定的切割质量的重要条件,有时透镜工作中因冷却不善而受热从而引起焦长变化,这就需及时调整焦点位置。

Focus position

The size of the spot is proportional to the length of the lens after the laser beam concentrating. After focusing on the short focal length lens, the light spot size is very small, the power density at the focus is very high and it is very favorable for the cutting of materials. But it is very short, and the adjustment allowance is very small, and it is generally suitable for high speed cutting thin material. For thick workpiece, long focal length lens has wider focal depth and is suitable for cutting if it has enough power density. Because of the highest power density at the focus, in most cases, when cutting, the focus position is just on the surface of the workpiece or slightly below the surface of the workpiece. To ensure that the relative position of the focus and the workpiece is constant is an important condition for obtaining a stable cutting quality, and sometimes the lens is heated because of bad cooling, which causes the change of the focal length, so the focus position should be adjusted in time.

辅助气体

激光切割时会产生很大的热量,如此高的热量集中到一起,就会使切割处的材料燃烧,发生氧化反应,而且还容易使被加工件产生变形。所以,需要加入一些辅助气体,常用的一般有氧气、空气、氮气。

辅助气体与激光光束同轴喷处,保护透镜免受污染并吹走切割区底部溶渣,对非金属和部分金属材料,使用压缩空气或惰性气体,清除溶化和蒸发材料,同时抑制切割区过度燃烧。

Auxiliary gas

Laser cutting will produce a lot of heat, so the high heat is concentrated together, which will cause the material to burn at the cutting place, the oxidation reaction, and the deformation of the processed parts. Therefore, some auxiliary gases need to be added. Commonly used are oxygen, air and nitrogen.

Auxiliary gas and laser beam coaxial spray, protect lens from pollution and blow away slag at the bottom of cutting area, use compressed air or inert gas to remove dissolving and evaporation materials for non metal and partial metal materials, and suppress excessive combustion in cutting zone.

辅助气体气压

激光切割时,气体和聚焦的激光束是通过喷嘴射到被切材料处。从而形成一个气流束。对气流的基本要求是进入切口的气流量要大,速度要高,以便足够的氧化使切口材料充分进行放热反应,同时又有足够的动量将熔融材料喷射吹出。

大多数金属激光切割则使用活性气体(氧气),形成与灼热金属发生氧化放热反应,这部分附加热量可提高切割速度1/3到1/2。

当高速切割薄板材时,需要较高的气体压力防止切口背面沾渣,当材料厚度或切割速度较慢时,气体压力可以适当的降低。

Auxiliary gas pressure

When laser cutting, the gas and the focused laser beam are projected through the nozzle to the cutting material. Thus a stream of airflow is formed. The basic requirement for the air flow is that the gas flow into the incision is large and the speed is high, so that enough oxidation is made to make the incisional material exothermic, and there is enough momentum to blow the molten material out.

Most metal laser cutting uses active gas (oxygen) to form an oxidation exothermic reaction with hot metal, which can increase the cutting speed of 1/3 to 1/2.

When cutting sheet metal at high speed, high gas pressure is required to prevent slag from the back of the incision. When the material thickness or the cutting speed is slow, the gas pressure can be properly reduced.

激光輸出功率

激光功率的大小对切割速度、切缝宽度、切割厚度和切割质量都有相当大的影响,激光切割机所需功率的大小是依据材料的特性和切割的机理而定,理想中的切割速度会使切割面呈现对比平稳的线条,且材料下部不会呈现熔渣。实际操作时,常常设置最大功率以获得高的切割速度或用以切割较厚的材料。

Laser output power

The size of laser power has great influence on cutting speed, slit width, cutting thickness and cutting quality. The power required by the laser cutting machine depends on the characteristics of the material and the mechanism of cutting. The ideal cutting speed will make the cutting surface present a smooth line, and the lower part of the material will not present the slag. . In practice, the maximum power is often set to obtain a high cutting speed or to cut thicker material.


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