共查询到20条相似文献,搜索用时 833 毫秒
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研究了一种激光熔覆快速修复与表面强化冲压模具的新技术,该技术特点是采用激光熔覆的方法和专用Ni基碳化钨合金粉末对模具的破损部位进行修复或对模具的表面进行强化.应用该技术对破损的高硬压轮模具进行了修复,得到了无气孔与裂纹的金属陶瓷层,延长了高硬压轮模具的使用寿命. 相似文献
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金属粉末激光快速成形技术是在快速原型技术和激光熔覆技术基础上发展起来的一项先进制造技术。鉴于它与传统制造相比所具有的突出优点,各研究机构竞相研究。其中美国激光工程化近净成形(LENSR)快速制造技术、Lasform^TM技术和金属直接沉积技术(DMD)代表了当今金属粉末激光快速成形技术发展趋势。论文介绍了我校实验室在这方面所做的一些研究工作。 相似文献
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激光熔覆是利用高能束激光热源辐射熔覆层和基材表面,使之熔化并迅速凝固,从而显著改善基材性能的一种新的工艺方法.由于熔覆层和基材的物理特性不一样,激光熔覆过程中必然产生热应力,其形态表现为拉应力.熔覆层表面在拉应力的作用下出现裂纹,严重影响了试件的质量.通过实验与建模,分析了熔覆层的应力类型,阐明了裂纹的形成机理,同时对试件进行预热和对熔覆层作微锻造处理,从机理和数学模型两个方面,论证了对熔覆层进行微锻造可以减少或消除熔覆层的拉应力,控制裂纹的产生. 相似文献
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Gang Pi Anfeng Zhang Gangxian Zhu Dichen Li Bingheng Lu 《The International Journal of Advanced Manufacturing Technology》2011,57(9-12):841-847
To improve the forming quality of parts fabricated by laser direct metal forming (LDMF), the forming process of three-dimensional parts under open-loop LDMF system was studied in this paper. The influencing rule of scanning space on the forming quality was studied, and the optimal scanning space was derived. The software of control system about scanning style is also optimized, and thus, the forming quality of parts is improved. During fabricating three-dimensional parts, uneven heat distribution caused by multi-overlapping is one of the main factors affecting the sidewall forming quality. To solve the uneven heat distribution, the strategy of changing scanning speed was put forward. The influence of the standoff distance on the height of single-trace cladding layer was studied, and it was suggested that uneven surface of parts was caused by instability of process parameters, which could be compensated automatically in the condition of suitable standoff distance in the process of LDMF. Thus a so-called self-regulation effect is reached. Typical multi-overlapped parts with good forming quality are fabricated using the above-mentioned methods. 相似文献
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通过特殊设计的电路及作用线圈制作了交变磁场发生装置,并用其研究了不同磁场强度对激光熔覆铁基涂层宏观形貌和显微组织的影响。基于电磁学及金属凝固原理,揭示了激光熔覆涂层的固化过程和磁场诱发熔覆涂层柱状树枝晶向等轴晶转变的主要机制。实验结果表明:在交变磁场作用下,熔池金属液表面产生的趋肤效应和交变电磁力使凝固后熔覆层的表面形态呈波浪式,熔高和横截面积均随磁场电流的增加而减小,但熔宽变化不大。熔池内部产生的电磁力驱动熔体流动使树枝晶熔蚀和机械折断,游离的破碎枝晶成为新的形核核心,增加了形核率,从而促使熔覆层顶部组织由树枝晶向等轴晶转变。随着磁场电流的增加,等轴晶区扩大,但涂层底部的组织变化不明显。 相似文献
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Zilin HUANG Gang WANG Shaopeng WEI Changhong LI Yiming RONG 《Frontiers of Mechanical Engineering》2016,11(3):242-249
Laser hot wire cladding, with the prominent features of low heat input, high energy efficiency, and high precision, is widely used for remanufacturing metal parts. The cladding process, however, needs to be improved by using a quantitative method. In this work, volumetric defect ratio was proposed as the criterion to describe the integrity of forming quality for cladding layers. Laser deposition experiments with FV520B, one of martensitic stainless steels, were designed by using the Taguchi method. Four process variables, namely, laser power (P), scanning speed (V s), wire feed rate (V f), and wire current (I), were optimized based on the analysis of signal-to-noise (S/N) ratio. Metallurgic observation of cladding layer was conducted to compare the forming quality and to validate the analysis method. A stable and continuous process with the optimum parameter combination produced uniform microstructure with minimal defects and cracks, which resulted in a good metallurgical bonding interface. 相似文献
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Shang-Liang Chen Ron-Lei Hsu 《The International Journal of Advanced Manufacturing Technology》1999,15(7):461-469
A pulsed Nd-YAG laser was adopted in this research in order to investigate the effects of ceramic–metal composite cladding
processes on Al-alloys. The effects of various compositions of substrate Al-alloys and ceramic–metal composite powders on
the cladding quality of high-power pulsed Nd-YAG laser cladding on Al-alloys was investigated using a constant energy intensity
to isolate the materials as the variable. The cladding of a (SiC + Al-Si) ceramic–metal composite layer onto an A6061 Alalloy
always caused serious shrinkage cavities within the substrate material. The cladding of a (WC + Al) ceramic– metal composite
layer onto an A6061 Al-alloy significantly reduced the number of shrinkage cavities created within the substrate layer. The
penetration depth of (WC + Al) cladding is, however, slightly less than that of (SiC + Al-Si) cladding. 相似文献
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Cr12MoV模具钢表面激光熔覆Ni/WC合金工艺研究 总被引:2,自引:0,他引:2
研究了Cr12MoV模具钢表面激光熔覆Ni/WC合金时激光功率、扫描速度和离焦量3个工艺参数对熔覆层性能的影响,并通过选择合适的工艺水平进行正交试验,从而得到熔覆层硬度和耐磨性能优良的较优工艺参数. 相似文献
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金属构件选区激光熔化快速成型铺粉控制系统研究 总被引:2,自引:1,他引:1
选区激光熔化(SLM,Selective Laser Mching)技术是直接将选区内金属或合金粉末逐层熔化,堆积成一个冶金结合,组织致密的实体,其外形不需进一步加工,经抛光或简单表面处理可直接作模具。本文是在自行研制的国内首台金属构件直接选区激光熔化实验样机设备基础上,介绍分析了该设备的控制系统,重点介绍了选区激光熔化设备铺粉控制系统,它是该技术能否达到预期目标的关键因素之一,并且对其铺粉精度进行了试验验证,为金属构件直接选区激光熔化成型工艺研究奠定了基础。 相似文献
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多道搭接激光熔覆工艺具有复杂性与耦合性,熔覆层质量受到工艺参数的直接影响.为确定最佳的工艺参数,以45钢表面多道搭接激光熔覆M2合金粉末为例,针对工艺参数对熔覆层宽度、表面平整度和稀释率的影响,设计相应的中心复合实验;通过灰色关联分析(GRA)建立熔覆层质量综合评价度,将多目标优化问题转化为单目标,并采用响应面分析法建... 相似文献