脲烷树脂砂三乙胺气体硬化工艺

本文对树脂砂吹三乙胺气体硬化主要工艺因素、供胺压力、时间、温度通过正交实验、极差分析,给出最佳工艺参数;论述了加热烘干树脂砂芯强度(抗压)变化规率、高温发气性,通过SEM扫描电镜观察从微观结构上分析树脂砂硬化、溃散机制,研究其热性能及对铸钢件质量的影响规率。     

强化呋喃V型树脂自硬砂

本文简述了采用附加物(邻苯二甲酸二锌酯改性的环氧树脂)对呋喃V型树脂进行改性,提高了树脂砂的常温及高湿强度,降低了树脂加入量,从而降低了树脂砂的发气量及树脂砂的成本,改善了劳动条件。     

呋喃树脂砂在工程机械零部件生产中的质量控制

从生产实际出发,对呋喃树脂自硬砂的主要工艺性能：强度、硬化时间和发气量的影响因素及其控制措施作了具体的介绍,并集中讨论了树脂砂生产中易产生的缺陷及应对措施。     

树脂砂在大型铸件砂芯上的应用

<正> 树脂砂是国内近年发展较快的一种新型造型材料,与普通粘土砂相比,具有强度高、透气性好、操作简单.易于清理和铸件表面平整光洁等优点。目前国內在中小复杂件上应用较广,而在复杂的大件上应用很少。为了将树脂砂用于我厂壁厚悬殊的大型复杂铸件砂芯,需寻求一种合理配方,并实施验证。经一年多的生产实践,现已成功地采用KJN-Ⅲ型冷硬树脂砂生产出近百吨铸件,其中最大件长5.65米,重8吨。     

云溪环保型砂铸造性能的研究

云溪环保型砂用于砂型铸造,能有效减少铸件的粘砂、夹砂、砂眼、气孔等缺陷,提高铸件的内在和外表质量;同时具备绿色环保、循环应用、优质高效的综合优势。通过系统的测试研究云溪环保型砂的湿压强度、透气性、热湿拉强度、发气性、高温热膨胀性能、高温热压强度,以及高温形态和示差扫描量热-热重分析(Differential scanning calorimetryThermogravimetric analysis,DSC-TG)曲线,并和传统的煤粉湿型砂进行对比,进一步认识云溪环保型砂的特点,进一步认识型砂性能对铸件缺陷和铸件质量的影响。研究表明,云溪环保型砂与煤粉湿型砂的湿压强度、透气性、高温热膨胀性能基本相似,而云溪环保型砂的热湿拉强度、高温热压强度、发气性等性能远远优于煤粉湿型砂,这些性能优势能有效减少铸件缺陷,保证铸件质量。研究工作对进一步提高铸件的品质和推行云溪环保型砂这一绿色环保铸造生产工艺具有基础性的指导作用。     

胺法冷芯盒制芯工艺研究

针对高强度铸铁发动机缸体、缸盖的生产实际,对三乙胺法冷芯盒制芯工艺进行了研究,指出砂芯强度表现为随着树脂加入量的增加而增大,芯砂发气量也是如此.当要求即时强度时,树脂加入量应大于1.8%,随着组分I所占比例的增加,砂芯强度呈现先增大而后减小,而芯砂发气量不断降低的趋势.     

防止冷硬树脂砂粘模的措施

采用冷硬树脂砂制造的砂型(芯),具有强度高、表面光滑、透气性好和溃散性好等优点。但是,冷硬树脂砂对模样和芯盒却有较强的粘附性,生产中若不采取措施加以防止,势必会影响砂型(芯)质量,降低生产率。我厂对上述问题主要是从以下几个方面解决的。一、模样和芯盒用冷硬树脂砂制造的砂型(芯)必须要在硬化以后才能起模,所以,要求模样表面和芯盒内表面要光滑,精度要高,拔模斜度可适当增大,不易出     

斗门砂的擦洗处理

铸型在浇注铁水后,型(芯)砂直接和液态金属接触,处于非常恶劣的条件下。因此,要求型(芯)砂不仅具有较好的高温性能,以防止铸件表面缺陷,而且应尽量降低粘结剂的加入量,以减少发气量而避免气孔缺陷,改善落砂清理性能,降低铸件成本。尤其是树脂砂,对这一要求更为突出。于是,需要寻找粒形圆,表面光洁、纯净的硅砂作为树脂砂的原砂。然而,天然砂粒表面总粘附着一层泥土和水化物膜,把砂粒和粘结剂隔开。并吸掉部分     

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。     

型砂有效煤粉量测定仪

邯郸市自动化仪表厂和清华大学联合研制的型砂有效煤粉量测定仪用于测定型砂中有效煤粉含量和各种制造材料的发气性。应用单片微机处理,直接打印出有效煤粉含量和最大发气量数据属国内外首创,达到目前     

围压状态下树脂砂的高温应力－应变及强度特性

通过高温三轴力学试验，揭示了围压对型砂应力－应变及强度特性的重要影响。提出了型砂修正的强度理论，并指出树脂砂的高温强度特性主要取决于其内摩擦特性。     

型砂的高温力学性能及应力-应变关系

本文对国内中、大型铸钢件生产中常用的几种型砂的高温力学性能进行了实验研究。通过测取型砂在不同温度下单轴压缩的应力-应变曲线,求得型砂在不同温度下的形变模量E,抗压强度σ p以及型砂软化后的粘度系数φ。通过测定试样的破坏角求出型砂的摩擦角ψ和粘聚力C。应用实验中获得的力学参数,建立了型砂在高温下的弹塑性或粘性的应力-应变模型。     

防止铸钢粘砂的黄壤土型砂性能与工艺研究

运用黄壤土型砂的烧结产生可剥离烧结层,可以有效防止铸钢件表面的粘砂类缺陷,提高铸钢件表面质量。调整黄壤土型砂的石英砂质量分数及粒径,进行不同温度下的烧结试验,研究适合不同温度下烧结的型砂配比。通过模拟烧结层试样的高温与室温力学性能测试,研究烧结层力学性能。依据型砂烧结试验和烧结层力学性能试验结果,将黄壤土和粒径为0.15～0.30 mm(50/100目)石英砂以3∶7配制的黄壤土型砂运用在铸钢件浇注试验,发现砂型与铸件界面产生一层致密的烧结层,并且在室温下可以轻易地从铸件表面剥离,获得表面光洁的铸钢件。研究表明,调整黄壤土型砂的成分可以调节型砂耐火度,使其满足在不同浇注温度下,在铸型—铸件界面处生成适度烧结的烧结层。该烧结层在高温下呈现良好塑性,粘附在铸钢件表面,抵挡金属液的冲刷和渗透;当铸钢件冷却至室温时,烧结层呈现出明显的脆性,可以很容易地剥离铸钢件表面,从而极有可能防止铸钢件的粘砂类缺陷,获得表面质量高的铸钢件。     

水玻璃砂落砂新方法

研究一种水玻璃砂铸件落砂方法。采用树脂砂作铸型的面砂,水玻璃砂作北极 散,填砂后一起紧实,一起吹ＣＯ２硬化。由于ＣＯ２硬化树脂砂溃散性好,浇注铸钢件不粘砂,浇注后的铸件就像穿了一层松散的外衣,很容易落砂,而且这种复合砂铸型突让性特别好,铸造不易产生热裂。     

抗震底座树脂模具强度研究

SLS技术处理后的烧结件用于模具时,为提高树脂模具的强度,对影响树脂模具强度的树脂混合液涂料质量、涂抹时间和涂抹后的固化处理工艺进行研究。试验表明,受树脂混合液涂料成分的影响,树脂混合液涂料应在45min内均匀涂抹在烧结件上;不同的烧结件所需要的树脂混合液涂料质量也有所不同;涂抹后的烧结件在常温下放置一段时间后再放入恒温干燥箱进行渐次升温固化处理可以明显提高树脂模具的强度。     

Fundamental studies on the brake friction of resin-based friction materials

The effects of various factors on brake friction were studied on the braking of a cast iron disk by small brake specimens made of resin, resin-asbestos composites and three-component composites. When the disk temperature rises, the resin-based composites containing asbestos and high melting point additive exhibit considerably lower friction during braking following high friction in the initial braking stage. The initial high friction is attributed to the deformation resistance of the resin in the composite. Low friction is attributed to the lubricating action of resin decomposition products in the neighbourhood of the filler raised to a high temperature by frictional heating. Increase of friction toward the end of braking is mainly due to increase of the true contact area as the frictional speed decreases. Variation of the average frictional coefficient during braking with load and the initial speed is generally small. There is no correlation between the mechanical properties and the brake frictional behaviour of resin-based composites.     

植物纤维真空模压成型设备控温装置的设计

为使植物纤维真空模压成型过程中树脂流动处于最佳工艺状态,在传统成型设备的基础上增加自动控温装置。该装置由DS182B20温度传感器实时采集模具温度数据,利用STC89C51单片机控制模具温度恒定,从而使充模过程中树脂受热粘度降低,加快在纤维束间的流动,缩短充模时间,提高成型效率。     

Measurement of the effective thermal conductivities of molding sands at high temperatures

It is well known that the effective thermal conductivity of bonded molding sands depends on the volume fraction, thermal conductivity and arrangement of the components e.g., sand particles, bonding medium and air. The arrangement of components is known to be affected by particle size distribution, average size and shape. In this study, an experimental system using the line-heat-source method was designed and effective thermal conductivities of molding sands at temperatures up to 750°C were measured. The effects of binder content, initial moisture content, dry density and temperature were also investigated for four selected sand types: silica, olovine, zircon and chromite sands. The effect of dry density on the effective thermal conductivity of bintonite-bonded molding sands turned out to be more significant than the effect of either binder content or initial moisture content. The minimum effective thermal conductivity for bentonite bonded silica sand occurred at about 500°C. The effective thermal conductivity of silica sands bonded with western bentonite was found to be higher than that of silica sands bonded with southern bentonite up to 750°C.     

数字化挤压梯度砂型性能及补压距离研究

作为一种新的无模铸造成形工艺,挤压切削一体化成形技术突破常规铸型制造方法,给梯度砂型的制备提供了新思路。在梯度砂型成形过程中,对砂型型面层的补压会引起其强度、透气性能及型面层厚度的变化,进而影响铸件性能。针对该问题,从强度、透气性和切削力等方面对不同型腔深度的梯度砂型型面层进行了研究。结果发现,对于相同型腔深度砂型,补压位移对砂型型面层性能影响很大,当补压位移在2～12 mm范围内时,补压位移越大,则砂型型面层强度越高,透气性越小,切削力越大。综合考虑砂型型面层透气性、强度和切削力,得到了不同型腔深度砂型的最优补压距离,并通过ZL114A铝合金浇注试验验证了梯度砂型的优越性。     

A model for prediction of the effective thermal conductivity of granular materials with liquid binder

A model is developed to predict the effective thermal conductivity of a three-component system containing sand particles bonded with liquid binders. The effective thermal conductivities of the bonded and unbonded sands are measured by the line-heat-source method at room temperature. The parameters of a two-component model are determined from the measurements for unbonded sands. Finally the model for the three-component systems such as bonded sand is developed using the assumption of the coalescence of the liquid binder at the particle contact points. Comparison between the experimental results and the model predictions shows that the model developed in this study predicts well the effective thermal conductivities of fluid-saturated sand or sand bonded with liquid binders. Also, this model can be used to determine the effects of the parameters such as the thermal conductivities and the volume fractions of components and the geometrical characteristics of solid particles on the effective thermal conductivity of granular materials with or without the liquid binder.