水玻璃砂——未来化学粘结剂砂的主力军

研制了一种获得国家实用新型专利的ＬＧＧ型水玻璃旧砂机械法再生机，成功地用于水玻璃再生后，再生砂的残留Ｎａ２Ｏ含量可降低到０．２％以下，并可单铬（１００％）地作为原砂使用。还研究了微波硬化水玻璃砂，其常温化强度是ＣＯ２硬化水玻璃砂的１２倍，水玻璃加入量可大幅度减少，因而其溃散性问题迎刃而解；还首次将纳米测试技术引入铸造研究领域，揭示了微波硬化玻璃砂强度高的原因。     

自硬呋喃树脂砂在低温高湿条件下的工艺措施

由于有机自硬树脂砂流动性好,能在常温下自硬,硬化后强度高、刚性好,落砂时溃散性好,旧砂再生后可反复使用,因此,采用自硬树脂砂可以节约能源,提高效率,减少占地面积,且易于清理;还可提高铸件形状尺寸的精确度和致密性,降低劳动强度,改善操作环境,并能减少铸件废品率,降低铸件综合成本等.正因为这样,自硬树脂砂得到越来越广泛的应用.我厂从日本太洋铸机公司引进自硬树脂砂混砂设备和旧砂再生体系.经过近两年的努力,解决了一系列工艺问题,现已稳定生产,并浇注了近千吨各类泵铸件.铸件重量从     

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     

酯硬化水玻璃自硬砂在铸造青铜合金中的应用

根据铸造镍铝青铜(Al9Ni4Fe4Mn2)合金的铸造性能,应用有机酯硬化水玻璃自硬砂取代传统的CO2硬化水玻璃砂铸型,使铸件的气源性缩孔、缩松、气孔、夹砂、结疤等缺陷大大降低,旧砂再生率明显提高,显著提高了铸件质量,降低了生产成本,同时提高了生产效率,改善了环境污染.应用有机酯硬化水玻璃自硬砂制作铸型后,水玻璃加入量为:2%～3%,仅是CO2硬化水玻璃砂中水玻璃加入量的1/3,同时铸型的强度稳定提高,使得铸型的吃砂量由300～400 mm降低为200～250 mm,从而铸型烘烤后的残留水分量显著减少,因此显著提高了铸件质量,气源性缩孔、渣孔缺陷由48.0%降低为3.5%,表面夹砂结疤缺陷由25.4%降低为4.5%.     

CO2水玻璃再生砂应用工艺研究

对ＣＯ２法硬化的水玻璃砂再生砂而言，造成再生砂制备的型砂性能恶化的主要原因是残留碳酸钠盐类的晶体及其碎片，ＪＺ添加剂的作用在于缓解残留钠盐对硬化作用有害影响。     

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     

酯硬化水玻璃砂的生产实践

以前我厂阀门类铸钢件的生产主要采用传统的CO2硬化水玻璃砂，生产过程中暴露出许多问题，如水玻璃加入量高(6％～8％)、型砂的残留强度高、溃散性差、铸件出砂清理及旧砂再生回用困难、型芯存放性差、硬不透、铸件外观质量差和型芯表面易粉化等。CO2硬化水玻璃砂工艺存在的上述不足，限制了铸件质量的进一步提高，急待解决。     

采用有机酯硬化水玻璃砂生产大型铸钢件

有机酯硬化水玻璃砂与树脂砂相比,具有无毒、价廉、成本低及对环境的污染小等优点,与粘土砂相比劳动强度低,节约大量能源,因而深受铸造工作者的欢迎。由于普通水玻璃砂的溃散性差,清理操作劳动强度大,多用于中、小件生产,而对大型铸钢件的生产效果不好,较少应用。经过实验研究和工艺改进,采用有机酯硬化水玻璃砂成功地解决了大型铸钢件的生产工艺问题。现介绍如下。     

水玻璃七○砂旧砂湿法再生

我厂于1975年5月初铸钢车间全面实现七○砂化,彻底丢掉硅砂,并利用原有水玻璃硅砂旧砂湿法再生作业线,进行七○砂旧砂湿法再生,现将其再生情况介绍如下。一、再生工艺铸型浇注后,在L128型落砂机上开箱与落砂,整个旧砂分三部分处理:     

CO_2硬化法水玻璃砂工艺存在的问题及解决途径

正水玻璃是除粘土之外应用最广的一种无机粘结剂。水玻璃砂也是最早的一种自硬砂。我国自20世纪50年代在铸造中应用水玻璃砂,主要用在铸钢件上,铸铁和有色合金铸件上用得较少。水玻璃砂混制非常方便,硬化主要是用化学硬化法,其与粘土砂相比有以下的优点。(1)水玻璃砂流动性好,易于紧实。(2)硬化快,简化造型和制芯工艺,缩短生产周期,提高劳动生产率。(3)铸造缺陷少,提高铸件质量。(4)可以硬化后再起模,型芯尺寸较准确,提高铸件尺寸精度。(5)可不用干燥炉,节约能源,改善车间劳动条件。     

STUDY ON PROPERTIES OF RECLAIMED SODIUM SILICATE SAND

ＳＴＵＤＹＯＮＰＲＯＰＥＲＴＩＥＳＯＦＲＥＣＬＡＩＭＥＤＳＯＤＩＵＭＳＩＬＩＣＡＴＥＳＡＮＤ①ＺｈａｏＧｕｏｐｉｎｇＪｉａｎｇＺｏｎｇｙｕＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＥｎｇｉｎｅｅｒｉｎｇ,ＪｉａｎｇｓｕＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅ...     

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。     

自硬涂料直接转移法的工艺研究

阐述转移性涂料的制备工艺。采用CO2水玻璃硬化背砂的铸造工艺及在自硬条件下涂料直接转移技术的工艺难点。提出相应的解决办法,并达到铸件生产周期短,成本低。表面光洁,尺寸精度高的目的。     

CO_2水玻璃再生砂应用工艺研究

对CO_2法硬化的水玻璃砂再生砂而言,造成再生砂制备的型砂性能恶化的主要原因是残留碳酸钠盐类的晶体及其碎片.JZ添加剂的作用在于缓解残留钠盐对硬化作用的有害影响.     

聚氨脂树脂砂性能研究

研究了HG、CP和NP三种聚氨脂树脂砂的透气性、发气量和在不同加热条件下的残留强度.结果表明:HG系列树脂砂透气性最高,CP系列树脂砂发气性总体上要优于其它两种树脂砂,发气量相对较低.树脂砂的高温残留强度随加热时间的增加而降低,加热温度越低,残留强度降低的幅度也越小;随着加热温度升高,树脂砂的残留强度显著下降,在500℃加热10min时,所有配比树脂砂的残留强度趋于零.CP2配比的树脂砂在透气性、发气性、溃散性和低温强度等方面有较好匹配,能更好地满足薄壁复杂铝合金件铸造成形需求.     

Optimal gating system design for investment casting of sterling silver by computer-assisted simulation

The first requirement of all casting processes is complete filling without any defects after solidification. However, casting defects often occur in casting processes, especially incomplete filling. The causes of incomplete filling are related to poor gating system, incorrect pouring, and molding temperature. A suitable shape and dimension of gating system will increase the melt flow while it is feeding into mold cavity by eliminating excessive pouring and molding temperature. The objective of this study is to develop a new design of gating system for eliminating incomplete filling. The new shape and dimension of pouring cup, main sprue, and sprue base are proposed and investigated. The computational flow model is solved with the aid of computer simulation. The targets of an optimum solution are increasing the efficiency of metal flow and reducing turbulence. The experiments are conducted to validate the simulation data. The results of this study will aid in the elimination of casting defects and increase the productivity.     

Effect of moulding sand on statistically controlled hybrid rapid casting solution for zinc alloys

The purpose of the present investigations is to study the effect of moulding sand on decreasing shell wall thickness of mould cavities for economical and statistically controlled hybrid rapid casting solutions (combination of three dimensional printing and conventional sand casting) for zinc alloys. Starting from the identification of component/ benchmark, technological prototypes were produced at different shell wall thicknesses supported by three different types of sands (namely: dry, green and molasses). Prototypes prepared by the proposed process are for assembly check purpose and not for functional validation of the parts. The study suggested that a shell wall with a less than recommended thickness (12mm) is more suitable for dimensional accuracy. The best dimensional accuracy was obtained at 3mm shell wall thickness with green sand. The process was found to be under statistical control.     

Effect of process parameters on impact strength of Al-7% Si alloy castings produced by VAEPC process

The castings produced by the evaporative pattern casting (EPC) process have blow holes. The blow holes in EPC castings are because of the non-escape of the gas produced as a result of burning of polystyrene pattern in the sand mold. To overcome the problem of blow holes, the EPC process is combined with the vacuum (V)- process. The vacuum applied to EPC mold draws the decomposed gases and improves the casting quality produced by the EPC process. The developed hybrid process has been termed as the vacuum assisted evaporative pattern casting (VAEPC) process. The objective of this paper to investigates the effect of process parameters, i.e, degree of vacuum, pouring temperature, grainfineness number, amplitude of vibration and time of vibration on the impact strength of Al-7% Si alloy castings in VAEPC process. In order to evaluate the effect of selected process parameters, the response surface methodology (RSM) is used to formulate a mathematical model which correlates the independent process parameters with the desired impact strength. The central composite rotatable design has been used to conduct the experiments. The results indicate that the impact strength decreases with increases in the grainfineness number and pouring temperature. Whereas, it has an inverse relationship with amplitude of vibration, time of vibration and degree of vacuum. The best value of impact strength (2.34 N/mm²) has been obtained at 400 mm Hg degree of vacuum imposed, 650°C as pouring temperature, 60 as sand grainfineness number, 460 μm as amplitude of vibration, and 70 s as time of vibration.     

型砂中的Na_2CO_3对铝液流动性的影响

研究了湿砂型条件下Na2 CO3对铝液流动性的影响并分析了其影响机理。结果表明 :随砂型中Na2 CO3含量的提高 ,型砂碱度增大 ,铝液流动性变差 ,是由型砂 铝液界面张力变大而造成的。