基于SLS的快速树脂模具技术研究

将环氧树脂和固化剂按不同比例混合后摇匀,分别涂抹在SLS烧结件上,测试SLS烧结件的固化时间和固化强度;并将涂抹后的SLS烧结件放在恒温干燥箱,研究不同温度下对烧结件的影响。试验结果表明,固化剂的用量和固化环境温度对烧结件有一定影响。     

树脂结合剂金刚石切割线的树脂层性能分析

针对树脂结合剂金刚石切割线树脂层强度和硬度低等问题,对树脂混合液固化后的性能进行了研究。通过正交试验,以剪切强度为指标,确立了最佳固化温度和固化时间。当树脂固化温度为180℃(60min)时的固化工艺下树脂粘结性能最优。制备了树脂金刚石切割线,进行了锯切试验,试验表明:制备的树脂金刚线性能较优,切片质量较好。     

环氧树脂快速模具材料配方及其固化工艺的研究

通过对金属树脂快速模具材料不同配方材料的硬度、弯曲强度及压缩强度等方面的比较,得出了性能较优的金属树脂模具快速材料配方,同时通过试验总结得出了该模具材料适宜的浇注固化工艺,并以得到的优秀材料配方及浇注固化工艺进行了典型模具试制。     

立体光造型成型材料的制备

以环氧树脂E-51和丙烯酸为基本原料,合成了立体光造型成型材料光敏树脂,通过比较不同树脂体系的固化度及显微硬度,优化了光敏树脂合成工艺;用硅烷偶联剂处理后的SiC纤维对光敏树脂进行了增强,比较了光敏树脂增强前后固化件的抗拉强度.结果表明:预聚物与单体三翔甲基丙烷三丙烯酸的质量比为2:1、光引发剂质量分数为3.5%时,树脂体系固化度最高,硬度指标较理想;光敏树脂经SiC纤维增强后,抗拉强度得到提高.     

嵌件注塑成型工艺技术的特点

嵌件成型（insertmolding）指在模具内装入预先准备的异材质嵌件后注入树脂，熔融的材料与嵌件接合固化，制成一体化产品的成型工法。     

改进模具结构 提高生产效率

本文结合注塑模具在生产中的故障粘模,由于生产用塑料原料由ABS树脂改变为AS树脂,模具结构上的相应调整过程.改进模具顶出结构,模具局部强度改善;将模具流道作了改进,彻底解决了粘模故障,显著提高了生产效率.     

工艺参数对低树脂基刹车片性能的影响

以正交试验法进行工艺参数设计,采用一次热压成型技术制备出低树脂基刹车片;利用多种分析测试设备测定低树脂基刹车片的摩擦磨损性能和机械物理性能;借助正交极差分析法判定各工艺参数对性能的影响程度,并观察磨损表面和磨屑的微观形貌。研究表明:热压温度对摩擦因数的影响最大,采用160℃热压温度处理的试样摩擦因数较高;固化时间对磨损率的影响最大,采用11 h固化时间的试样磨损率较低;压力对硬度的影响最大,采用22 MPa压力的试样硬度大;固化时间和热压温度都影响剪切强度,在一定范围内,固化时间越长热压温度越高则剪切强度越高。     

树脂型面快速经济模具制造及其在汽车试制及小批量生产中的作用

轿车模具的生产在我国起步时间并不长。1997～1998年,我们成功研制出全新小红旗轿车改型10个蒙皮件的树脂型面拉深模(附带研制1套整形模、1套翻边整形模),达到了三个目的:组装样车,进行整车性能试验;检验产品工艺性、冲压工艺、拉深模工艺补充合理性,提高生产准备质量,加快换型步伐;摸索树脂模具制造经验,为汽车试制和小批量生产提供树脂型面快速经济模具。     

碳纤维复合材料板热冲压成形试验研究

材质轻量化和结构轻量化是降低汽车整质重量的有效途径。其中,质轻且比强度高的纤维增强树脂复合材料已经越来越多的应用于汽车设计和制造中。为解决传统复合材料件成形效率低、制造成本高等问题,进一步扩展复合材料在汽车制造业中的应用,提出一种采用非等温模具对复合材料板直接进行热冲压的复合材料成形新方法。该方法对模具进行非等温加热,使用非等温模具通过接触传热将复合材料中需要发生变形的区域进行局部加热,借助复合材料加热到一定温度下软化的特点,随着模具的运动逐步成形工件,工件在模具作用下固化。进行复合材料板球面形件的热拉深成形试验研究,分析成形温度对试件拉深过程的影响。试验结果表明,碳纤维增强树脂基复合材料具有良好的热冲压性能,成形效率高,成形的球面件质量好,表面光洁。由于树脂软化,拉深过程载荷随着成形温度升高而降低。     

大型干式变压器中VPI工艺问题分析

某企业大型干式变压器在真空加压浸漆中出现以下问题:浸漆结构件检测出电镀不符合要求;真空度和压力值初调高于VPI工艺要求值;生产中硅钢片的冲切油混入树脂;局部结构出现树脂不能完全固化;铁芯及夹件表面质量达不到要求;浸漆后线圈表面质量有待改善等。本文针对上述质量问题进行了分析并提出了相应的解决方案。     

碳化硅零件的激光选区烧结及反应烧结工艺

为了获得高密度、高性能、复杂结构的碳化硅陶瓷件,提出采用机械混合法制备含有黏结剂和乌洛托品固化剂的碳化硅复合粉体,对复合粉体进行激光选区烧结（SLS）形成陶瓷素坯,并对素坯进行气氛烧结和渗硅处理,使其与基体发生反应烧结,最终形成复杂陶瓷异形件。实验证明：若激光功率为8.0 W、扫描速率为2 000 mm/s、扫描间距为0.1 mm、单层厚度为0.15 mm,获得的 SLS 陶瓷样品密度和强度最好。对SLS试样进行合理的中温碳化和高温渗硅,所得碳化硅陶瓷烧结体的抗弯强度最高可达 81 MPa,相对密度大于86%。     

Investigation into manufacturing injection mold via indirect selective laser sintering

Cooling system of an injection mold is important for the promotion of production rate and the quality of injection plastic components. Conformal cooling channels are newly developed temperature-adjusting method to promote the efficiency of cooling system. They can be made in the injection mold inserts via the method of indirect selective laser sintering combined with traditional powder metallurgy. This work discussed some processes such as thermal transmission, powders removing, and metal melt infiltration during the manufacturing of the mold inserts in detail. The result showed that redundant powders outside of laser-scanned areas might be sintered together with the sintered parts owing to the accumulation of laser energy during sintering process. This was solved by switching the temperature to initial level after one layer had been sintered. A limit length corresponding to some certain power vacuum system was found when the removal of unsintered powders in the cooling channels was carried out. Therefore, some subsidiary channels leading the cooling channels outside were made to help the removal of powders within the cooling channels. Dripping method was adopted during metal melt infiltration process, which was proven to be relevant for maintaining of the final shape of infiltrated inserts.     

Development of high gloss plastic for injection molding by utilizing wollastonite(CaSiO<Subscript>3</Subscript>) and talc fillers

The gloss of plastic products is an important factor with which customers rapidly and directly decide the value of product. In general, these high-gloss plastic molded parts are produced through the injection molding of glass fiber-added plastic resin using a high temperature mold with the fine surfaces like glass. However, making the mold temperature higher causes the cooling time of injection molding longer, and the prolongation of cooling time leads to the extension of whole cycle of injection molding process. In order to resolve this problem, we developed a resin which makes the high-gloss injection modeling possible at low mold temperature by replacing conventional glass fiber filler with wollastonite filler. The tensile strength, flexural strain, impact strength, flow rate, gloss level and so on of the developed resin were tested with respect to the content of wollastonite. The results show that most of the properties except for the flow rate and gloss level are reduced in the newly developed resin. However, the decline in these properties was not enough to limit the use of new resins. In the gloss level test, as for the equal gloss of injection molded parts, the mold temperature for the developed resin was 30 °C lower than the mold temperature for the conventional resin. The difference of gloss between two injection molded parts using two different resins has been confirmed from the surface inspection of injection molded parts by SEM (scanning electron microscope).     

环氧树脂粘结剂在大型冷冲裁模具中的应用

环氧树脂粘结剂应用于大型冷冲裁模具的主要零件进行粘结固定,是一项技术创新。它缩短了模具的制造周期,保证了模具的精度,它还具有粘结强度高,零件变形小、维修方便的特点。     

Research on manufacturing Cu matrix Fe-Cu-Ni-C alloy composite parts by indirect selective laser sintering

The property of alloy parts can be adjusted conveniently if alloy element powders are used for manufacturing alloy parts by indirect selective laser sintering (SLS), but there have been no reports in this field. Fe, Cu, Ni, C composite powders of two compositions were obtained through a 3D blending way in this paper. Green parts of above composite powder were manufactured by indirect SLS. Then, Cu matrix Fe-Cu-Ni-C alloy composites were produced after green parts had been depolymerized, high temperature sintered and infiltrated by molten Cu. The post-processing of green parts, microstructure and mechanical properties of alloy composites were investigated. The results show: Ni, Cu and C diffuse into γ-Fe when green parts are being sintered at high temperature and the distributing non-uniformity of alloy elements is eliminated basically; at room temperature, alloy composite microstructures are composed of lower bainite, α-Cu precipitated out of γ-Fe and Fe-Ni after they have been solution treated at 930°C and held at 350°C for 1 h later; the yield strength of alloy composites is near to 400 MPa and the elongation is under 3%. It can be used for manufacturing injection mold or other functional parts by indirect SLS.     

覆膜钼粉激光烧结成型件的高温烧结工艺研究

高温烧结是选择性激光烧结后处理工艺的关键问题之一，传统上高体积质量的合金烧结采用单一液相烧结法，但这种烧结方法不适用于保形性差的激光烧结件。通过对覆膜钼粉脱脂预烧结件进行真空固相烧结与还原气氛二步烧结，研究2种高温烧结件的组织及性能后发现，还原气氛对改善烧结体组织具有显著作用，二步烧结可以实现保持制件形状的液相烧结。     

Study on direct fabrication of ceramic shell mold with slurry-based ceramic laser fusion and ceramic laser sintering

Through studying the porosity of the ceramic parts fabricated with slurry-based rapid prototyping process of ceramic laser fusion and ceramic laser sintering, the feasibility of directly fabricating ceramic shell mold was investigated in this paper. Although the total porosity of the fusion part was low, microcracks led to low strength, which was hardly enhanced by post-treatment of infiltration. On the other hand, by adjusting the slurry formulation and varying the laser scanning energy, the open porosity of the sintered part was over 90?vol.% of the total porosity. High open porosity resulted in good permeability, which is one of the important characteristics of the ceramic shell mold for investment casting. To verify the feasibility of producing casting part with ceramic shell molds fabricated by the processes of ceramic laser fusion and ceramic laser sintering, the casting process was conducted to obtain the casting parts.     

Chemo-mechanical grinding by applying grain boundary cohesion fixed abrasive for monocrystal sapphire

This paper presents a novel fixed abrasive tool namely grain boundary cohesion fixed abrasive pellet (GBCFAP) which is able to provide higher finishing efficiency as well as better surface/subsurface quality of sapphire substrate during the chemo-mechanical grinding (CMG) process. The manufacturing procedures of GBCFAP are introduced in detail in this paper. It is found that the sintering temperature plays an important role to the strength of GBCFAP, and the strength of GBFCAP could be flexibly adjusted by sintering temperature. The experiment result suggests that the recommended sintering temperature ranges from 600 to 650 °C according to current CMG conditions. Meanwhile, comparing with conventional resin bound CMG wheel, 600 °C sintered GBCFAP CMG wheel performs better in terms of material removal rate and surface/subsurface quality since the chemical effect and mechanical effect during CMG process are well balanced. Meanwhile, the solid phase reaction between sapphire and Cr₂O₃ abrasive is demonstrated by TEM observation and XPS quantification.     

SLS预热温度场温度补偿研究

由于预热粉床的温度分布不均匀,很难获得强度、精度较高的烧结制件,针对以上问题,提出了通过温度补偿改善预热粉床的温度分布不均匀对激光烧结成型制件质量的影响,通过温度补偿调节粉床的温度分布,从而提高了烧结制件的质量,并对粉床温度场进行有限元模拟。研究结果表明,增加热源的方式对预热粉床进行温度补偿可以明显改善温度场;通过试验获得了温度补偿的最佳工艺组合。