选择性激光烧结工艺参数对影响铸造砂型精度的优化设计

阐述了选择性激光烧结(SLS)的成型原理,并将此成型方式运用于直接砂型制作。通过用自主研制的快速成型机进行烧结试验,采用正交试验和方差分析,对影响铸造砂型精度的工艺参数进行了优化设计,得到激光功率、扫描速度、扫描间距及铺粉厚度工艺参数的最佳组合,可为基于选择性激光烧结铸造砂型的制造提供指导和参考。     

基于选择性激光烧结技术的快速铸造

介绍了用选择性激光烧结（ＳＬＳ）快速成型技术直接制造覆膜砂铸型（芯）的特点及工艺过程。结合铸件生产,分析研究了ＳＬＳ铸型（芯）的工艺设计、三维实体造型及铸型后处理等过程中所遇到的问题。     

覆膜砂选择性激光烧结过程的建模研究

建立选择性激光烧结粉末的快速成型工艺过程的数值计算模型,并用于估算热固结宽度和深度.在该计算模型中,综合考虑了材料的热物性参数随温度变化的情况和激光光强分布不均匀的因素,采用Ansys有限元分析软件模拟计算激光点加热过程覆膜砂的热影响区大小,结果与实验吻合较好.     

选择性激光烧结铸造覆膜砂的实验研究

通过对铸造用覆膜砂烧结实验,激光功率、扫描速度、预热温度、光斑直径工艺参数对烧结试样成型精度和烧结质量的影响,总结出了制件尺寸随各工艺参数变化的趋势。并提出烧结制件后处理的合理温度范围。     

基于选择性激光烧结覆膜金属纳米复合粉末材料的研究进展

综述了选择性激光烧结金属粉末材料和纳米粉末材料的研究进展。介绍了选择性激光烧结覆膜Al-Fe-Ni合金系金属纳米复合粉末材料的开发思路。提出了选择性激光烧结覆膜Al-Fe-Ni合金系金腻纳米复合粉末材料的主要成分与制备方法，并对前景进行了展望。     

Rapid casting technology based on selective laser sintering

Selective laser sintering (SLS), as a kind of additive manufacturing technology, which uses a laser beam to scan and heat powder material layer by layer to form parts (models), is widely used in the field of casting, mainly for preparing casting coated sand cores, investment casting patterns, etc. The SLS technique facilitates rapid casting and shortens the casting production periods by eliminating mold preparation. In this study, we reached conclusions for the basic principles and characteristics of SLS methods, and focused on the research status, key technology and development trend of SLS in the fields of forming coated sand-casting molds and investment casting patterns.     

基于SLS的随形冷却通道注射模间接快速制造技术

介绍了在广泛考察国内外制造随形冷却通道注射模技术的基础上,摈弃普遍采用的直接制模技术,提出将选择性激光烧结(SLS)技术和铸造工艺相结合,间接快速制造随形冷却通道注射模的新的制造工艺方法。利用SLS技术对腹膜砂和环氧树脂混加的材料成型注射模的布尔结构铸造砂型,对砂型进行后处理后,浇注铝合金形成模具铸件,最后对模具铸件进行清粉和后处理,完成注射模制造。同传统的随形水路模具制造技术相比较,本方法能成型较为复杂的随形冷却通道,并且由于直接用铝合金铸造成模具,其致密度、强度和尺寸精度相比较传统的脱脂、高温烧结和低温浸渍改性的环氧树脂等工艺方法得到的模具性能大幅度提高。该注射模寿命可达50 000次/副,强度可达588 MPa。从塑件质量可以得出,此工艺是一种快速制造适合小批量生产注射模的切实可行的方法。     

激光快速成型砂型铸模用烧结剂的制作和应用

介绍了激光快速成型砂型铸模用的一种烧结剂的制作和应用。这种烧结剂是一种改性酚醛树脂，它和作为耐火骨料的原砂混合制成覆膜砂作为激光烧结材料更加适用于激光快速成型过程。     

激光快速成型用覆膜砂工艺性能探讨

探讨了激光快速成型用覆膜砂的工艺性能对激光烧结成型、铸型精度和铸件质量的影响，进而得到适用于激光快速成型方法直接制造铸件铸型用的覆膜砂烧结材料。     

基于SLS的无模砂型制造工艺研究

以轮形铸件为例,研究基于激光选区烧结（Selective Laser Sintering,SLS）技术直接烧结覆膜树脂砂铸造壳型的新工艺。该工艺可由铸件三维数字实体模样“反求”精铸型壳实体模型,利用SLS技术直接烧结覆膜树脂砂,制造铸造型壳,然后对砂型经过适当后处理,成功浇注了铸铝、铸铁和铸钢件。对此工艺的相关问题进行了分析、研究、改进,实现了基于SLS的无模砂型制造工艺,为单件、小批量复杂铸件生产提供了一种敏捷、经济的数字化先进制造方法。     

Direct laser sintering of a copper-based alloy for creating three-dimensional metal parts

Direct laser sintering of metal, as one of the important developments in rapid prototyping technologies, is discussed in this paper. A special copper-based alloy is used for this rapid prototyping process. Experiments on the sintering conditions of this material had been conducted in a self-developed high temperature metal sintering machine. The mechanism of laser sintering for this kind of material was disclosed by SEM analysis of microstructures of sintered parts. The density, surface roughness and mechanical properties of the laser sintering parts due to variation of process parameters were measured and analysed. The effect of process parameters to the accuracy of sintered parts was also investigated. Thus, optimum parameters were obtained for direct laser sintering of three-dimensional metal parts.     

预处理工艺对SLM成型CoCr合金牙冠牙桥金瓷结合机制及性能的影响

为了探究打磨喷砂预处理SLM成型CoCr合金基底对修复体的金瓷结合的影响机制,进而为SLM成型具有良好力学性能的CoCr合金牙冠牙桥修复体提供参考。采用SLM优化工艺参数成型3组CoCr合金基底试样,分别进行不同的打磨、喷砂预处理以相互对照,之后以相同参数进行烤瓷烧结。采用三点弯曲试验、粗糙度测试、SEM及EDS等测试方法分析不同对照组试样;测试结果表明,经过打磨和喷砂预处理的a组试样的金瓷结合强度达到36.79±0.49MPa,明显高于不打磨而保留SLM成型特征表面b组试样,以及打磨处理而不喷砂的c组试样,三组试样的平均金瓷结合强度均高于ISO9693：1999标准规定的最小值25MPa。a、c组的金瓷结合效果优于b组,3组试样的金瓷结合界面均发生元素扩散,分析还发现3组金瓷剥落面的残留物及其剥落面元素分布有显著差异;最终结论为：打磨、喷砂组合预处理获得的一定粗糙度的基底表面可保证金瓷间强大的化学结合以及可观的机械结合,可以显著提高SLM成型金瓷修复体的性能。     

复杂内腔结构金属零件的快速制造

介绍了一种通过激光烧结砂芯快速制造具有复杂内腔构造金属零件的方法,通过案例归纳了该种方法的技术特点和应用范围。     

IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLTC POWDER MATERIAL

How to directly fabricate metallic functional parts with selective laser sintering (SLS) process is a potential technique that scientists are researching. Existent problems during directly fabricating metal part by use of SIS are analyzed. For the sake of solving the problems, a new idea of adding self-propagating high-temperature synthesis (SHS) material into metallic powder material to form new type of SIS metallic powder material is put forward. This powder material can release controllable amount of heat during its interaction with the laser beam energy to reduce the requirement to laser power during directly sintering metallic part, to prolong the time of metallic liquid phase existing, and to improve the intensity and accuracy of SIS part. For this reason, SHS material‘s interaction with the CO2 laser beam energy is researched, which proves that CO2 laser beam energy may instantly ignite SHS reaction. On the basis of the above-mentioned researches, the effect of sintering the metal powder material mixing SHS material with CO2 laser is also researched,which shows: there is an optimal blending ratio of various material in the new metallic powder material. Under the optimal blending ratio and SIS process parameters, this new metallic powder material can indeed release amount of heat and SHS reaction may be controlled within the laser sintering. This research result makes it possible that the metallic part is directly sintered with small CO2 laser (less than 50W), which may greatly reduce the volume, cost and running expenditure of SIS machine, be propitious to application.     

Selective laser sintering mechanism of polymer-coated molybdenum powder

A type of polymer-coated molybdenum powder used in selective laser sintering technology was prepared by coating polymer on molybdenum particles and frozen grinding techniques, with the maximum particle diameter of 71 μm. The laser sintering experiments of polymer-coated molybdenum powder were conducted by using the self-developed selective laser sintering machine （HLRP-350I）. The method of microscopic analysis was used to investigate the dynamic laser sintering process of polymer-coated molybdenum powder. Based on the study, the laser sintering mechanisms of polymer-coated molybdenum powder were presented. It is found that the mechanism is viscous flow when the laser sintering temperature is between 100 ℃ and 160 ℃, which can be described by a two-sphere model; and the mechanism is melting/solidification when the temperature is above 160 ℃.     

粉末烧结激光快速成形数字化制模技术及应用

快速成形技术是将三维CAD模型直接转化成为铸造用模的新技术。介绍了粉末烧结激光快速成形数字化制模的原理，探讨了在产品开发设计、精密铸造用蜡模、精密铸造用砂型、直接烧结金属零件和模具等方面的应用。与传统制模方法相比，具有速度快、精度高、价格便宜等优点。     

覆膜砂选择性激光烧结原型件的后处理试验研究

对铸造覆膜砂的激光快速成型进行了试验研究。系统研究了激光功率、扫描速度、预热温度、铺粉厚度工艺参数对成型试样质量的影响规律,结果获得了铸造用激光快速成型砂型试样。     

IGNITING SHS BY LASER AND ITS APPLICATION TO SELECTIVE LASER SINTERING OF METALLIC POWDER MATERIAL

1.IntroductionSelective laser sintering (SLS) is one of typical rapid prototyping (RP) technology. SLS adopts the idea of a delamination manufacturing, which is not limited by complicated degree of part shape and not needs any frock & mould, to directly fabricate three dimension (3D) solid parts with powder materials. Theoretically, any powder materials, which can felt each other after they are heated, may be SLS materi-als. Range of SLS materials have covered with polymer powder, cerami…     

激光烧结用复合蜡粉的筛选及成型工艺研究

研制开发了几种复合蜡粉,经过烧结测试,筛选出了一种适合激光选区烧结用精铸蜡粉。研究了激光烧结性能和烧结成型工艺,得到了激光烧结成型最佳工艺参数。结果表明,筛选出的精铸蜡粉最佳烧结为激光功率10 W、预热温度60℃、激光扫描速度2 000 mm/s、铺粉厚度0.15 mm。     

选择性激光烧结硅砂的实验研究

对间接选择性激光烧结硅砂进行了实验研究，通过对烧结后硅砂显微组织的观察，得出了硅砂烧结的机理。分析了激光功率、扫描速度、搭接量、光斑直径、粉末成分配比等工艺参数对烧结试样尺寸精度和烧结质量的影响，并得出了优化的工艺参数。烧结成形了一些砂模，经后处理后可用于铸造生产。