Laser Applied Rapid Prototyping of Metallic and Ceramic Dies

在所提出的工艺中，激光在金属粉末的表面上扫描以制造线，然后通过制造具有间隙的平行的许多线可以制造表面。通过添加层，可以形成三维模型。首先用CO_2激光扫描各种金属粉末，观察其凝固特征。结果表明，铜粉可以制成凝固块体，但在凝固块体内部存在大量的孔隙。为了减少空隙，将粉末压实并增加初始密度。虽然通过这种方法减少了空隙，但由于更大的热传递，需要更多的能量。从凝固过程的简单分析可知，热传导率和激光吸收率是影响成形特性的主要因素。为了进行有限元分析，测量了具有一定密度的各种金属的传热系数。利用该系数，用Dev软件模拟了粉末的凝固行为 ...更多信息 开发了有限元程序。通过有限元分析，发现具有高峰输出的脉冲激光器是理想的，并且下一步采用脉冲型YAG激光器，并且寻找适合于该工艺的材料。由于该过程被认为是连续的包覆，因此测试了Ni基和Cu基包覆材料。通过使用包覆材料，获得几乎没有空隙的固化线材。力学性能测试结果表明，Ni基合金凝固后的硬度值约为800Hv，Co基合金凝固后的硬度值约为600Hv。虽然凝固的镍基合金是脆性的，但通过热处理改善了它。最后提出了一种新的三维模具成形方法。由于通过该工艺制造大型主体需要很长时间，因此仅表面壳体和支撑部分通过激光原型制造，其余部分通过低熔点金属的铸造填充。通过简单形状的三维模型验证了该方法的有效性。少

In the proposed process, laser is scanned over the surface of metallic powders to make a wire, and then by making many wires in parallel with a gap a surface could be made. By adding the layrs, three dimensional model could be formed. At first CO_2 laser is scanned over various metal powders and the solidified features are observed. It is found that solidified blocks can be made with copper powders but many voids are left inside of the block. To reduce the voids, the powders are compacted and the initial density is increased. Although the voids are reduced by this method, much more energy is needed due to a greater heat transfer. From the simple analysis of solidification process, the forming characteristics are affected by the heat conductivity and the rate of laser absorption. To carry out finite element analysis, heat transfer coefficients of various metals with some densities are measured. By using the coefficients, the solidification behavior of the powders is simulated by the dev … More eloped finite element code. By using the finite element analysis, it is found that pulse laser with a high peak output is desirable, and pulse type YAG laser is employed for the next step and the materials suitable for this process is looked for. Since the process is considered to be a continuous cladding, Ni base and Cu base cladding materials are tested. By using the cladding materials, solidified wires with almost no voids are obtained. From the result of mechanical testing, the hardness numbers of the solidified Ni base alloys are about 800Hv and that of Co base alloy is about 600 Hv. Although the solidified Ni base alloy is brittle, it is improved by heat treatments. Finally a new method of forming a three dimensional die is proposed. Since a long time is needed to make a large body by this process, only the surface shell and the sustaining parts are to be made by laser prototyping and the remaining parts are filled by casting of lower melting point metals. The proposed method is ascertained by some simple shaped 3D models. Less