喷墨频率对砂型3D打印结果影响的研究

以砂型3D打印中的喷墨频率为研究对象,分析和验证了喷墨频率对喷射墨滴以及砂型打印结果的影响.通过墨滴观测仪对不同喷墨频率下的墨滴状态进行了观测,并通过压力波传导理论对喷墨频率变化与喷射墨滴影响效果之间的关系进行了分析.对于砂型3D打印,喷墨频率与打印扫描速度及扫描分辨率直接相关,并进一步影响到砂型树脂加入量,通过对各变...     

Nanofabrica推出微米级3D打印技术

<正>近日,位于以色列的精密增材制造技术开发商Nanofabrica推出微级分辨率3D打印技术,其工艺基于数字光处理(DLP),与自适应光学相结合,可实现可重复的微米级分辨率。Nanofabrica表示,这是自适应光学系统首次应用于3D打印技术,其3D打印平台能在厘米级的零件上实现1μm的分辨率,凭借其50 mm×50mm×100 mm的构建体积,可以在单个构建中输出数千个零件。     

3D打印用石膏粉料的研究与应用

针对3D打印用石膏粉料的要求,选择了合适的石膏基料、黏结剂,促凝剂、分散剂及其他粉末助剂,经过大量试验及生产实际验证,成功研制了一种3D打印用石膏粉料,得出了最佳的改性工艺及工艺配比。实践表明,研制的3D打印用石膏粉料性能优异,环保无毒、粉末流动性好,均匀细腻,铺粉均匀顺畅,没有皱褶;渗透合适,产品表面光洁,尺寸稳定,不易收缩,打印精度好;打印过程,无粉末飞扬,不会堵塞打印头;硬化后强度较好,效果比较理想,很好地解决了目前3D打印石膏粉料的固化慢、流动性差、强度较低等问题。     

3D打印用精密铸造粉末材料性能影响因素的研究

通过正交试验研究了耐火材料粉末种类、粉末目数、助熔剂种类、焙烧温度对3D打印用精密铸造粉末的高温抗压强度、高温抗拉强度、尺寸收缩率、表面粗糙度的影响。结果表明,确定的3D打印用精密铸造粉末的最终材料为添加氧化铜的325目锆英粉在1 400℃下焙烧得到抗压强度为45.42 MPa、抗拉强度6.78 MPa、尺寸收缩率为6%、表面粗糙度Ra为3.45的高性能型壳。     

基于喷墨3D打印的铸造砂型（芯）成形工艺参数应用研究

通过正交试验的方法研究了材料(旧砂比例)、工艺参数(打印层厚、X方向分辨率)对铸造型(芯)初始抗拉强度的影响规律。研究发现:增大旧砂比例砂型强度有所下降;随着打印层厚的增大,强度逐渐减小,灼减量减小;X方向分辨率与粘结剂加入量有关,随着X方向分辨率的减小,粘结剂加入量增大,强度增大,灼减量增大。另外,打印层厚对强度影响最大,X方向分辨率次之,旧砂比例最小。最终确定最佳打印参数为:旧砂比例30%、层厚0.28 mm、X方向分辨率0.09 mm,基于该参数打印的砂型(芯)能够很好地满足铸造要求。     

驱动波形参数对压电喷墨墨滴的影响

在现代工业制造中,喷墨3D打印技术因其独特的优势发展迅猛,已替代60%的传统的手工制造,成为不可或缺的新技术。压电喷墨打印头的驱动脉冲即波形对墨滴喷射有很大的影响,其控制着墨滴的喷射过程和喷射质量。本文就QS压电喷墨打印头的驱动波形参数对喷墨效果影响进行了研究。通过使用墨滴观测仪观测并捕捉墨滴下降过程,测量墨滴体积和喷射速度,得到喷射电压、脉冲宽度即斜率对墨滴体积和喷射速度的影响。当喷射电压增大时,墨滴体积和速度均增大,不同的喷头和喷射墨水对应一个最佳的脉冲宽度和斜率范围。     

基于FDM的3D打印参数优化实验研究

以熔融沉积制造技术中常用的基体材料PLA作为对象,通过3D打印实验,对打印过程中的因素参数进行优化实验研究。利用单因素实验法和正交实验法,以打印时间和打印尺寸误差为实验指标,选取层厚、打印速度和喷嘴温度三个主要因素展开实验。实验结果表明,层厚为0.3mm,打印速度为20mm/s,喷嘴温度为200℃时,可以在保证打印质量的情况下获得最短打印时间。对打印效率影响程度由大到小依次是层厚,打印速度,喷嘴温度,并进一步通过实验验证。     

世界最大的3D打印系统VX4000落户美国投入运营

<正>德国3D打印公司维捷(Voxelje)t为提高其在美国市场的存在度,在美国密歇根州坎顿市(Canton,Michigan)的运营公司投入运营了世界上最大的3D打印系统。这台VX4000 3D打印设备(图1)提供世界最大连续打印砂型体积。打印尺寸为4 000 mm×2 000 mm×1 000 mm(长×宽×高),相当于大众高尔夫轿车的体积。VX4000 3D打印机速度快,易操作。除了能经济有效的打印非常大的单个砂型以外,这个巨大的3D打印设备可以用于打印小型铸型,或者结合起来同时打     

三维打印快速成形及其试验研究

利用自行开发的三维打印快速成形系统进行了石膏基复合粉末的三维打印快速成形试验,讨论了三维打印快速成形的机理和过程.利用正交试验研究了工艺参数中层厚、喷射扫描模式以及辊子转速对制件的密度、抗压强度及3个方向上尺寸精度的影响.试验结果为制定合理的三维打印快速成形工艺参数提供了依据,并通过实例给予验证.     

变速箱壳体3D打印熔模铸造工艺分析北大核心CSCD

以变速箱壳体铸件试制为例,分析了3D打印蜡模石膏熔模铸造技术路线、关键工艺过程和应用效果,对3D打印蜡模及铸件产品精度进行了测量分析。结果表明,3D打印蜡模石膏熔模铸造技术工艺过程稳定,铸件精度高,适用于快速试制铝合金铸造新产品样件。     

Effect of binder saturation and powder layer thickness on the green strength of the binder jet 3D printing (BJ3DP) WC-12%Co powders

Printed parts displaying good green/handling strength are vital for the Binder Jet 3D Printing (BJ3DP) process to succeed in manufacturing complex parts with thin sections and tiny intricate features. A study was carried out to understand the effect of the binder saturation and powder layer thickness on green strength of the printed samples. The ability of using the green strength data of the samples to identify the optimum processing conditions for printing was examined. The strength of the parts were evaluated after printing at binder saturation levels of 45–75% and powder layer thickness of 50-70 μm. For any given powder layer thickness, the strength of the samples increased with increase in binder saturation. The samples printed at 60 and 75% saturation showed similar strengths at 50 and 60 μm layer thickness. However, the strength decreased with further increase in powder layer thickness to 70 μm. Doubling the binder set time and increasing the binder saturation options were evaluated to minimize the difference in the strength of the parts printed at 60 and 70 μm thickness. Increasing the binder saturation was found beneficial in minimizing the difference in the strength of the parts printed at 60 and 70 μm thickness compared to doubling the binder set time.     

Effect of gel time of 3D sand printing binder system on quality of sand mold/core

Two important factors affecting the performance of sand mold/core generated by 3D printing (3DP) are strength and dimensional accuracy,which are not only closely related to the reactivity of furan resin and the phase transition of silica sand,but also the curing agent system of furan resin.This paper studies the influence of gel time on the strength and dimensional accuracy of a 3DP sand mold/core,taking the furan resin system as an example and using a sand specimen generated by a 3DP inkjet molding machine.The experiment demonstrates that the gel time of 3 to 6 min for the sand mixture suits 3DP core-making most under the experimental condition.However,it should be noted that under the same resin condition,the strength of a no-bake sand mold/core is higher than that of a 3DP sand mold/core.The dimensional accuracy of the sand mold/core does not change significantly when the gel time is less than 15 min.Improving the activity of binder and developing ultra-strong acid with low corrosion shall be an effective way to improve the quality of the mold/core by 3D printing.     

Binder jetting 3D printing process optimization for rapid casting of green parts with high tensile strength

Binder jetting 3D printing is a rapid, cost effective, and efficient moulding/core making process, which can be applied to a large variety of materials. However, it exhibits a relatively low green-part strength. This may cause the collapse of the printed parts during de-caking and the pick-up procedure, especially in the case of small-scale structures, such as thin walls, tips, and channels. In this work, polyvinyl alcohol (PVA) was used as the additive in coated sand powder. By exploiting the binding effect between the two composites (thermoplastic phenolic resin and PVA) triggered by the binder, bonding necks firmly form among the sand particles, improving the green-part strength of the coated sand printed parts. Experiments based on the Taguchi method were used to investigate the relationship between the process parameters and the green-part tensile strength. The following set of optimal process parameters was identified:50wt.% alcoholicity of the binder, 75% binder saturation, 0.36 mm layer thickness and 4.5wt.% PVA content. Further, the effect of such parameters on the green-part tensile strength was determined via statistical analysis. The green part of an engine cylinder head sand pattern with complex cavity structures was printed, and the green-part tensile strength reached 2.31 MPa. Moreover, the ZL301 aluminum alloy impeller shape casting was prepared using sand molds printed with the optimal process parameters. The results confirm that the proposed binder jetting 3D printing process can guarantee the integrity of the printed green parts and of small-size structures during decaking and the pick-up procedure. Furthermore, the casting made from the printed sand molds exhibits a relatively high quality.     

激光3D打印AlSi10Mg铝合金点阵结构材料的组织和力学性能

以不同激光3D打印参数制备了AlSi10Mg铝合金点阵结构材料,探索其最优化打印参数,研究了铝合金点阵结构材料的组织和性能,以及后续热处理对其组织性能的影响。结果表明,最优化打印参数为:环境温度80 ℃,粉层厚度30 μm,激光束直径80 μm,激光能量370 W,激光扫描速度1300 mm/s。制备的铝合金点阵结构材料空洞缺陷少,致密性高,显微组织呈一层层交错堆垛的激光熔池,为细小的α-Al等轴胞状晶和球状Si颗粒相组成,性能良好。经热处理后,原激光熔池缺陷、等轴胞状晶特征消失,Si颗粒相不断析出并长大,硬度和静态压缩试验下的平台应力降低,压缩性能下降。     

球形钨粉的制备及应用

球形钨粉以其良好的流动性、高的松装密度和振实密度广泛应用于喷涂、增材制造等材料制备领域。本文以不规则形状钨粉颗粒为原料,采用射频等离子球化技术制备球形钨粉,并对球形钨粉进行铺粉及成形实验效果评价。在射频等离子球化过程中,研究球化工艺参数（送粉速率、送粉位置）和原料粉末形态对球化结果的影响。在铺粉实验方面,研究粉末特征和铺粉层厚对铺粉效果的影响。采用扫描电子显微镜、激光粒度分析仪和BT-100粉体综合特性测试仪对球化处理前后粉末的形貌、粒度、流动性、松装密度和振实密度进行测试和分析。结果表明：经过球化处理后,钨粉颗粒呈规则球形,表面光滑,球化率可达100%,流动性、松装密度和振实密度得到明显提高。球化率高的粉末流动性好,铺粉效果好;随着层厚的增加,铺粉效果逐渐得到改善;采用合适粒径的球形钨粉打印的钨薄壁件表面相对光洁,尺寸精度高。     

增材制造用高流动性铝合金粉末制备技术研究

采用自主开发的旋转盘离心雾化实验装置进行雾化制备增材制造用铝合金粉末实验研究,通过开展雾化盘实验研究优选出粒度分布较均匀收得率较好的盘形,并获得其结构和工艺参数的影响规律;通过对制得的铝合金粉末性能和3D打印成型件物理性能进行检测。结果表明:离心雾化制备的铝合金粉末具有高流动性、窄粒度、高球形度、高松比,表面光洁无卫星粉,无空心粉等特点,同时3D打印离心雾化样件熔覆道均匀,孔洞缺陷少,致密度和力学性能明显优于气雾化样件,尤其是抗拉强度和屈服强达到495和320 MPa,相比气雾化粉打印样件提高近10%。     

三维光学扫描技术在3D打印中的应用

采用先进的三维光学扫描技术,借助计算机软件对SLS打印的缸盖上水夹层砂芯进行三维数字化全尺寸扫描,检测分析了SLS打印砂芯尺寸精度及尺寸变化规律。检测结果显示:上水夹层砂芯不满足打印设备精度要求,需要改进打印工艺。根据三维光学扫描检测分析结果明确了3D打印工艺调整方向,改进了工艺打印的缸盖上水夹层砂芯,经过三维光学扫描检测,砂芯尺寸精度得到了有效地提高。通过对三维光学扫描技术在3D打印中的应用研究,对SLS打印砂芯精度检测提供了一种更为准确直观的测量方法,三维光学扫描检测结果作为SLS打印工艺参数调整依据,为SLS打印出合格的砂芯奠定基础。     

Effects of process parameters on dimensional precision and tensile strength of wax patterns for investment casting by selective laser sintering

Turbine blades, produced by the directional solidification(DS) process, often require high dimensional accuracy and excellent mechanical properties. A critical step in their production is the fabrication of wax patterns. However, the traditional manufacturing process has many disadvantages, such as long-term production, low material utilization rate, and the high cost of producing a complex-shaped wax pattern. Selective laser sintering(SLS) is one of the most extensively used additive manufacturing techniques that substantially shortens the production cycle. In this study, SLS was adopted to fabricate the wax pattern instead of the traditional manufacturing process. The orthogonal experiment method was carried out to investigate the effects of laser power, scanning speed, scanning space, and layer thickness on the dimensional precision and morphologies of the SLS parts. The SLS parts showed a minimum dimensional deviation when laser power, scanning speed, scanning space, and layer thickness were 10 W, 3000 mm·s-1, 0.18 mm, and 0.25 mm, respectively. In addition, the tensile strength and fracture morphologies were closely associated with the laser volumetric energy density(VED). The tensile strength reached a maximum when the VED was 0.0762 J·mm-3, with an evident brittle fracture morphology. The wax pattern manufactured in this way meets the accuracy and strength requirements for investment casting. This research offers a novel path for the production of wax patterns for complex-shaped turbine blades by SLS.     

3D打印送粉器技术的发展研究情况综述

简单介绍了3D打印技术的历史发展状况。通过分析和论述了现在3D打印送粉器技术在国内外的研究和发展情况,知道国内外的发展还有一定的差距。并且还重点指出了目前3D打印送粉器技术存在着粉末利用率低、材料的限制和送粉不均匀等问题以及提出了可能解决问题的方法。在此基础上,还对3D打印技术未来的发展趋势进行了概括。