共查询到20条相似文献,搜索用时 93 毫秒
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铁基粉末冶金材料的温压工艺 总被引:1,自引:1,他引:0
介绍了温压技术的工艺过程和致密化机制,采用温压工艺制备铁基粉末冶金材料,优选出了适合于温压工艺的聚合物添加剂,并确定了其最佳压制温度范围。试验表明,采用温压工艺可提高材料的生坯和烧结体密度以及力学性能 相似文献
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以水雾化CuZn30黄铜粉末为主要原料,微晶蜡等有机物为粘结剂,经混炼、破碎和过筛得到打印喂料,通过粉末挤出3D打印制得打印坯体。以层厚、挤出温度、挤出率和打印速度为研究因素,以生坯密度为响应指标,采用中心复合设计(Central Composite Design, CCD)进行实验设计,并建立响应面分析数学模型。实验结果表明:在实验优化范围内,打印件的生坯密度大小主要由层厚和挤出温度决定,当层厚为0.25 mm、挤出温度为150℃、挤出率为140%、打印速度为50 mm/s时可获得生坯密度最高的打印坯体。 相似文献
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采用水雾化铁粉,分别加入不同含量的润滑剂,以常温压制与温压两种压制方式成形,温压温度为130℃;测量了压坯、烧结坯的密度和弹性后效,并进行了对比与分析.结果表明:润滑剂的适量加入可以提高粉末的流动性以及减小其与模壁间的摩擦力,从而得到更高的压坯密度与烧结密度,加入量最佳值为0.4%(质量分数)左右;同时,温压可提高粉末的生坯密度、烧结密度,并且可以降低弹性后效和脱模力;常温压制的压坯密度和烧结坯密度最高值分别为6.89和7.10 g·cm-3,而温压的则提高至7.06和7.26 g·cm-3. 相似文献
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大功率发动机高性能粉末冶金油泵齿轮研究 总被引:1,自引:0,他引:1
通过对大功率发动机油泵齿轮使用状况的分析,进行了油泵齿轮的弯曲强度、接触疲劳强度和有限元分析计算;研制了高性能粉末冶金温压齿轮材料,与原采用的合金钢材料进行了摩擦磨损对比研究;采用粉末冶金温压旋转模模壁润滑方式压制了机油泵斜齿轮,与合金钢齿轮加工工艺、材料利用率和制造成本加以比较。进行了齿轮的轮齿折断试验、部件可靠性试验、整机耐久性试验,结果表明,在发动机全寿命周期内,所研制的粉末冶金温压斜齿轮耐磨性好、强度高,油泵供油量下降少,满足发动机各种工况的使用要求。 相似文献
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《机械工业标准化与质量》2016,(9)
本文提出了一种用于激光选区烧结(Selective Laser Sintering,SLS)成形的新型粉末材料KZF。研究了其适合进行SLS成形的粉末制备工艺,基于不同的激光加工工艺参数,得出了最优工艺参数。在最优工艺参数下SLS成形KZF粉生坯体具有较高的初始强度,得出了成形KZF生坯所需粘接剂的最低含量,和具有的强度值。研发了SLS成形的KZF生坯件的后处理材料、配方及工艺规范,研究了经确定最佳后处理规范后的KZF-SLS成形件的力学性能以及微观组织的影响,确定了提高KZF生坯强度的材料及含量,经后处理后的KZF-SLS成形件的弯曲强度提升幅度最大达273倍。本文为制造复杂形状的KZF成形件提供了一种新的思路与方法,并扩大了SLS成形材料的应用范围。 相似文献
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The dynamic hardness measurement using a scratch indentation is a convenient technique for assessing the local surface mechanical properties of a material. In the present study, this method was used to obtain both the local wall and internal density distributions for ceramic powder compacts. The method has been applied to investigate cylindrical samples of agglomerated aluminas prepared using single acting planar punch compaction in cylindrical dies. The study shows that this method is capable of detecting even very small changes in the properties of the sample. For example, it shows that along the planar surface adjacent to the moving punch (loaded at 87 MPa) of a cylindrical compact there is a change in the density from 2.35 g/cm3 to 2.46 g/cm3. In addition the approach is capable of mapping the internal density distribution within the compact. In agreement with the results obtained in previous studies, this technique also shows that the strength of this type of compact decreases if the compaction pressure increases to a value of ca. 380 MPa. 相似文献
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利用MSC/MARC有限元分析软件对金属粉末温压过程进行了模拟分析。采用基于更新拉格朗日方法的热—机耦合分析方法分析了不同压坯高径比对压坯性能(相对密度、等效应力)的影响规律。结果显示:在相同的侧压系数下,不同的初始松装高度与压坯直径对压坯相对密度分布影响不大,其分布规律基本一致;随着侧压系数的增大,压坯相对密度分布愈加不均匀,差值越来越大,低密度区域逐渐扩大。对压坯等效应力分布状况进行了研究,结果表明:侧压系数的分布呈X形,与镦粗变形相似,在X形的空心区域等效应力较低,是"摩擦死区",在X形的线区域等效应力较大,是"易变形区";随着侧压系数的增大,摩擦死区逐渐增大,同时随着初始松装高度的增大,压坯等效应力增大。 相似文献
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Ju-Won Kim Yong-Bin Im Jong-Soo Kim 《Journal of Mechanical Science and Technology》2006,20(7):1059-1067
In order to develop a compact evaporator, experiments that show characteristics of evaporating heat transfer and pressure
drop in the helically coiled minichannel were performed in our previous research. This study was focused on the performance
analysis of helically coiled heat exchangers with circular minichannels with an inner diameter=1.0 mm. The working fluid was
R-22, and the properties of R-22 were estimated using the REFPROP program. Numerical simulation was performed to compare results
with the experimental results of the helically coiled heat exchanger. As the heat transfer rate and pressure drop were calculated
at the micro segment of the branch channels, the performance of the evaporator was evaluated. The following conclusions were
obtained through the numerical simulations of the helically coiled heat exchanger. It showed good performance when the flow
rate of each branch channels was suitable to heat load of air-side. The numerical simulation value agreed with experimental
results within ± 15%. In this study, a numerical simulation program was developed to estimate the performance of a helically
coiled evaporator. And, an optimum helically coiled minichannels evaporator was designed. 相似文献
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金属粉末零件压制过程有限元模拟的研究 总被引:10,自引:1,他引:9
论述粉末压制过程的建模理论,建立屈服准则中静水应力影响因子与粉末压坯密度之间的动态关系式。在此基础上,运用有限元方法对回转类粉末压制零件进行计算机模拟,结果印证理论分析,并与实验结果相符。 相似文献
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以Fe-1.8Ni-0.5Mo-1.2Cu-0.2C预合金粉为原料,采用温压、烧结、渗碳、淬火与低温回火的工艺制备了粉末冶金齿轮,利用光学显微镜、扫描电子显微镜和硬度仪等研究了齿轮的组织与性能。结果表明:温压压坯的密度为7.35g.cm-3,相对密度为94.2%;烧结态齿轮的显微组织主要是珠光体和铁素体,硬度达到46~54HRA,密度为7.37g.cm-3,相对密度为94.5%,烧结态齿轮有轻微收缩现象,但其仍表现出良好的尺寸稳定性;热处理后齿轮渗碳层的组织主要由回火马氏体和少量残余奥氏体组成,齿轮断齿扳力为9.6kN,硬度提高至66~75HRA。 相似文献
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The biaxial compaction of a square array of circular cylinders is studied using slip-line field, upper bound and finite element methods. Densification is assumed to occur by plastic deformation at the contacts. It is found that contact–contact interaction has a softening effect on the local indentation pressure at each contact. The yield surfaces resulting from hydrostatic and closed-die compaction are constructed at various stages of densification: the size and shape of the yield surface depend upon the loading history and upon the relative density of the compact. The finite element predictions suggest the formation of a vertex at the loading point for the entire densification process in the case of isostatic compaction. On the other hand, a vertex at the loading point is formed only for a relative density D0.85 in the case of closed-die compaction. 相似文献