原砂处理对酯硬化水玻璃砂强度的影响

1.前言 原砂是型(芯)砂的基本骨料,其质量好坏必将直接影响型砂的强度和粘结剂的加入量,最终影响铸件的质量和成本。在采用树脂砂生产时,我们对这方面的认识已较深刻,而对采用酯硬化水玻璃砂生产时,这方面的认识还远远不够。现阶段我们对酯硬化水玻璃砂用原砂的认识还停留在原来采用CO_2硬化砂的水平上。由于CO_2硬化砂的水玻璃加入量高达7％～8％,又含有     

铸造用冷法覆膜砂新工艺

1.前言 随着对铸件质是的要求不断提高,树脂覆膜砂得到日益广泛的应用。目前,覆膜砂的生产方式主要有热法覆膜和冷法覆膜工艺两大类。由于冷法覆膜工艺的工艺过程简单,设备投资较小,生产灵活性大,耗能也小得多,对中小企业具有较大的优越性。为提高冷法覆膜砂的性能,我们对普通的冷法覆膜工艺进行     

覆膜砂射芯机射砂口的设计

由于覆膜砂属于流动性良好的干态砂,因此用普通热芯盒射制覆膜砂型芯时,若不对射砂口作适当改造,射砂结束时覆膜砂会因自重而从射砂口中流入芯盒。作者在此介绍在日本进修铸造技术期间所见到的四种覆膜砂射芯机射砂口,以供有关铸造人员作参考。     

铣削覆膜砂用微型硬质合金铣刀磨损规律的研究

针对覆膜砂复杂铸型铣削加工过程中的刀具磨损问题,以刃口覆Ti Al N涂层的钨钴类硬质合金整体式微型平底铣刀铣削覆膜砂作为试验对象,使用光学影像测量仪观察并分析了刀具在各个磨损阶段的形貌特征及变化,确定了刀具最终的磨损状态。对刀具磨损处进行能谱分析发现,在磨损过程中出现了大量的涂层脱落。利用双对数线性方程对试验数据进行分析得到了铣削覆膜砂时微型硬质合金铣刀寿命与主轴转速之间的对数方程。     

对SLS覆膜砂制件抗压强度的研究

主要对覆膜砂的激光烧结快速成形进行了实验研究.系统分析了激光功率、扫描速度、扫描间距、铺粉厚度对成形制件抗压强度的影响.最后得出了最佳成形工艺参数.实验结果对于提高制件的抗压强度有指导意义.     

对SLS覆膜砂制件抗压强度的研究

主要对覆膜砂的激光烧结快速成形进行了实验研究。系统分析了激光功率、扫描速度、扫描间距、铺粉厚度对成形制件抗压强度的影响。最后得出了最佳成形工艺参数。实验结果对于提高制件的抗压强度有指导意义。     

硬酯酸钙对覆膜砂砂芯起皮的影响

酚醛树脂覆膜砂热芯盒砂芯外表贴近芯盒迅速固化,紧靠上表层硬壳处常常“起皮”。经初步探讨其成因与树脂质量、固化条件、射芯工艺等直接相关。在一定条件下通过控制硬酯酸钙加入量来减轻起皮倾向,简单有效。     

我国铸造覆膜砂的生产、应用与展望

论述了我国铸造覆膜砂的生产及应用情况。简要介绍了我国覆膜砂的发展历程、特点、原材料的选择、混制工艺及分类 ,着重介绍了覆膜砂的制芯 (造型 )工艺 ,特别是热芯盒制芯及壳芯制作工艺 ,覆膜砂生产铸件常见缺陷及解决措施以及覆膜砂的再生与质量控制等。展望了我国覆膜砂技术的发展方向及应用前景     

我国铸造覆膜砂的生产、应用与展望

论述了我国铸造覆膜砂的生产及应用情况。简要介绍了我国覆膜砂的发展历程、特点、原材料的选择、混制工艺及分类,着重介绍了覆膜砂的制芯（造型）工艺,特别是热芯盒制芯及壳芯制作工艺,覆膜砂生产铸件常见缺陷及解决措施以及覆膜砂的再生与质量控制等。展望了我国覆膜砂技术的发展方向及应用前景。     

覆膜砂热芯盒芯头部分的综合改进

我厂生产的蜗轮箱是柴油机增压器的重要零件,质量要求非常高。其气道部分为变截面螺旋通道,为铸造非加工表面,形状和表面要求严格,我厂采用在射芯机上用覆膜砂热芯盒方法制芯。由于覆膜砂的特性决定芯砂只能一次性使用,其费用占据了铸件成本的一个较大的比例。为了减少芯砂的使用量,我们在模具的设计和制造中采取了多种措施,同时还要考虑到取芯难易程度、生产效率的提高、加热耗电的多少和型芯质量的高低,这些因素经常互相制约。经过多年生产实践,我厂已形成了不同形式和结构的模具。现仅对芯头部分的不同形式进行分析,以求找出较好的改进方案。 现以某型号气道芯子为例。其芯子尺寸与形状如图1所示。     

树脂砂铸件的粘砂问题的解决

大中型树脂砂铸钢件生产的主要缺陷是粘砂,影响因素是树脂砂的强度、涂料性能、浇注温度。     

08－32捣固机捣固装置液压试验台

０８－３２捣固机是铁路系统养路作业的主要机械设备，本文对其捣固装置液压试验台的功能、设计原理及结构做了详细的介绍     

粘结法制备磁性磨料的研究

采用粘结法制备磁性磨料 ,并对各种磨料进行磁力研磨试验。研究磁性磨料的配比、粘结剂的选择以及粒度对不锈钢管 1Cr18Ni9Ti的材料去除量和表面粗糙度的影响。试验结果表明 ,使用环氧树脂A制备的磁性磨料具有较好的研磨效果 ,磨料中Fe与白刚玉粉较为合适的配比是 4∶1,磨料的粒度为 80目时研磨效果较佳。     

Wear of ceramic nozzles by dry sand blasting

Monolithic B₄C, Al₂O₃/(W,Ti)C and Al₂O₃/TiC/Mo/Ni ceramic composites, which provided a reasonably wide range of mechanical properties and microstructure, were produced to be used as nozzles materials. The erosion wear of the nozzle caused by abrasive particle impact was compared with dry sand blasting by determining the cumulative mass loss of the nozzles made from these materials. Results showed that the hardness of the nozzle material plays an important role with respect to its erosion wear. On the nozzle entry bore section, the B₄C nozzle appears to be entirely brittle in nature with the evidence of large scale-chipping, and exhibited a brittle fracture induced removal process. While the erosion mechanism of Al₂O₃/TiC/Mo/Ni nozzle appeared to be a preferential removal of the metal binder followed by pluck out of the undermined Al₂O₃ and TiC grains under the same test conditions. On the nozzle center bore zone, the B₄C nozzle fails in a highly brittle manner, and there are lots of obvious micro-cracks and small pits located on this area. While the primary wear mechanisms of Al₂O₃/TiC/Mo/Ni nozzle is plowing and micro-cutting by the abrasive particles. Both types of material removal model seem to be occurred for the Al₂O₃/(W,Ti)C nozzle.     

Roughness variability in the honing process of steel cylinders with CBN metal bonded tools

Herein are presented roughness results of honing of steel cylinders with cubic boron nitride (CBN) abrasive tools. Different honing parameters such as honing stone pressure against the workpiece, tangential speed of the honing head as well as grain size of the abrasive stone were varied in order to determine their influence on the surface roughness of cylinders. Four different strategies were implemented to measure and characterise roughness of inner surfaces of honed steel cylinders. The variability in results obtained with each strategy is compared. The first three strategies consist in measuring roughness at one, three or nine points, respectively, which are uniformly distributed over a circumference located at one of the cylinder ends. The fourth strategy is based on the third one: it entails measuring roughness at nine points, and then subsequently filtering results to eliminate any extreme roughness value lying outside the boundaries set by Chauvenet's criterion. At each point of measurement, roughness is measured in the direction of the cylinder generatrix. It was verified that the larger the number of measurement points, the lower the variability in roughness values obtained. Therefore, it is recommended to make at least nine measurements per cylinder and to filter values to avoid any non-representative, outlier value. The variability in these values was quantified firstly according to relative differences. Secondly, variability was quantified by means of the coefficient of variation which provides smaller values than the relative difference, although less intuitive and less direct.     

Experimental research on KDP crystal slicing with resin bonded diamond abrasive wire saw

This paper shows the development of software that calculates and generates the 3-D printing path for tissue engineering (TE) scaffolds. It is compatible with Fab@Home platform, which works with additive manufacturing (AM) extrusion processes. The software was named BioScaffolds PG; it allows obtaining 0/90^° architectures of square and circular scaffolds. In the software interface, the user can easily define the scaffold geometry, then, it generates a file with a continuous path, which can be exported to the 3-D printer software; the continuous path is an advantage since the 3-D printer does not need to stop the process between layers, minimizing morphological defects related to the AM process. Several tests were carried out to evaluate the compatibility between BioScaffolds PG and Fab@Home softwares. Furthermore, polycaprolactone (PCL) scaffolds were fabricated and morphologically characterized, where suitable scaffold morphologies were obtained. It was found that the software works properly and can be used in TE researching to reduce the computer-aided design (CAD) time usually required in this kind of applications.     

Performance of single vertical helical anchor embedded in dry sand

An investigation into the uplift behavior of single vertical helical anchor embedded in dry sand presented. A series of laboratory tests have been conducted to determine the effect of the embedment ratio, shaft diameter ratio and sand density against the uplift capacity of helical anchor. The laboratory tests were conducted in a small scale model in loose and dense sand. A sand placement technique was utilized over the testing program to achieve the predetermined depth. In this testing program, the uplift load and uplift displacement have measured. The observation of failure mechanism and the measurement of pullout load and the vertical displacement analyzed and discussed. A number of graphs will be plot between the uplift capacity and the factors to obtain their relationships. From the analysis, the uplift capacity is increase with the increase of embedment ratio and sand density however the shaft diameter ratio is not significantly influent to the uplift capacity. In the observation of failure mechanism, the failure surface proposed for the helical anchor embedded in loose and dense sand. For loose sand package, local failure surface observed however for dense sand package, a truncated cone shape failure surface was observed. From the analysis, an empirical model was proposed. The proposed empirical model compared with the experiment result and existing theories to verify the validity of the empirical model.     

Tribological performance of raw and formulated RBD palm kernel with ZDDP additive

This study compares tribological performance of refined, bleached and deodorized (RBD) palm kernel (PK) as an alternative lubricant. An analysis was made for chemically modified RBD PK with zinc dialkyl dithiophosphate (ZDDP) additive to determine its tribological performance using modified pin-on-disc tribotester. Commercial mineral oil (SAE 40) was used as the benchmark in this study. The conditions for this experiment are sliding speed at 1.5 m/s, a normal load at 9.81 N, weight percentage of ZDDP for 0, 3 and 5%, lubricant quantity of 2.5 ml and test duration of 60 min. The findings revealed that RBD PK oil exhibits better anti-friction and anti-wear performance compared to commercial mineral oil (SAE 40). Besides, coefficient of friction is less dependent on ZDDP concentration, but anti-wear ability is dependent on the ZDDP additive concentration. ZDDP additive acts as a good anti-wear and antioxidant additive in RBD palm kernel.     

自硬呋喃树脂砂工艺性能研究

介绍了自硬呋喃树脂砂工艺性能的研究情况,并进行了工艺性能测试,制定出自硬呋喃树脂砂工艺性能标准,也为自硬呋喃树脂的工艺性能改进提供了理论基础。     

细长管内壁喷砂除锈作业线的设计

以 2 5英寸防腐油管为研究对象 ,采用先进的喷射装置和砂粒的自动回收与分离技术 ,设计一条细长钢管内壁喷砂半自动作业线。试验结果 :作业线动作准确 ,工作稳定 ,除锈质量达到瑞典工业标准Sa2 5级 ,生产率达30m2 /h以上。同时配合三废治理 ,改善了劳动条件 ,是替代钢管酸洗的理想工艺 ,可望在石油、化工、机械等领域内得到广泛应用