连续激光高速抛光冷作模具钢的表面粗糙度及性能

目的解决连续激光高速抛光模具钢的表面质量与效率问题。方法将连续激光高斯光束通过缩束镜和DOE衍射整形器,转变成平顶激光光束。通过激光抛光工艺参数的优化,将光斑直径为470μm的平顶连续激光束,以之型与方波型组合扫描路径和500 mm/s的高速扫描速度,抛光冷作模具钢Cr12MoV,并通过白光干涉仪和SEM电镜检测其表面性能。结果连续激光高速抛光可将表面粗糙度由原始的1.942μm快速降低至0.26μm,抛光效率比传统机械抛光提高了67%,比人工抛光提高了94%,表面显微硬度提高了125%。结论工艺试验表明,连续激光的光斑扫描路径和直径对抛光表面质量产生深远的影响,对冷作模具钢进行高速抛光时,需要对激光功率、光斑直径、扫描速度、扫描路径和扫描间距等激光加工参数进行优化,在达到相同质量效果的前提下,抛光效率是传统机械抛光效率的8倍以上,是熟练技师人工抛光效率的30倍以上。同时,连续激光抛光显著提高了模具钢的表面显微硬度,无任何污染,是一种绿色制造技术。

Roughness and Property of CW Laser High Speed Polishing of Die Steel

The work aims to solve the efficiency and quality problem of rapid continuous wave(CW)polishing of die steel surface.The CW laser Gaussian beam was converted into a flat-topped laser beam through a beam-shrinking mirror and a DOE diffraction shaper,so as to shape the CW laser beam and adjust the spot diameter.By optimizing the parameters of CW laser polishing process,the surface tension of molten pool was increased by combining scanning paths of zigzag pattern and square wave pattern while high laser scanning speed was maintained.The molten pool was promoted to flow around to make the peaks of microstructure generate material migration under the action of tension and flow to the valleys,thus achieving the purposes of filling peaks and valleys and reducing surface roughness.The flat-topped CW laser beam with a spot diameter of 470μm was used to polish the die steel Cr12MoV with a combined scanning path of zigzag pattern and square wave pattern and a high-speed scanning speed of 500 mm/s.The original surface roughness Ra 1.942μm could be rapidly reduced to Ra 0.26μm through the detection of white light interferometer and SEM electron microscope and the polishing efficiency was 67%higher than that of traditional mechanical polishing,94%higher than that of manual polishing and 125%higher than that of surface microhardness.Technological experiments show that the spot diameter of CW laser has a profound influence on the polishing surface quality.When CW laser is used to polish die steel surface,the laser processing parameters such as laser power,spot diameter,scanning speed,scanning route and step-over need to be optimized.On the premise of achieving the same quality effect,CW laser polishing efficiency is more than eight times that of the traditional mechanical polishing processes and more than 30 times that of skilled technicians'manual polishing.CW laser polishing can significantly improve the surface microhardness of die steel surface and is a kind of environment-friendly manufacturing technology without any pollution.