【作者】 孟令伟；

【导师】 万国庆； 王志刚；

【作者基本信息】 哈尔滨理工大学 ， 材料工程， 2005， 硕士

【摘要】 用湿型砂气冲造型生产铸钢件是一种经济而有效的生产方式,铁路货车用铸钢件批量大,钢种品种少,易于组织连续生产。湿型砂混制简单,成型后不需要任何处理,下芯后可浇注。它和射压、静压等高压造型同属高密度造型。它是以压缩空气为动力,瞬间成型。它与普通机器造型相比,由于砂型的湿压强度高,硬度分布均匀,因而获得铸件的尺寸精确、表面光洁、组织致密、机械性能提高、生产率高、劳动条件改善。气冲造型的硬度分布比一般的高压造型更合理,砂型中靠近模样的部分硬度高,背面的硬度低,砂型的退让性好。另外,它的设备简单,比较灵活,动力价格低廉。因此,湿型砂的开发和应用前景非常广阔。型砂对铸件的质量影响很大, 通过此次课题研究,把湿型砂的性能做进一步的改进优化,来充分发挥气冲造型的优越性,减少铸件的气孔、粘砂、冲砂、胀箱、裂纹、夹砂、变形等铸造缺陷。在整个课题的研究过程中,准备分两步进行,首先进行探索性实验,初步确定要达到的型砂性能指标,然后在型砂组成中分别加入不同量的新砂、膨润土、淀粉、MD 粉,检测型砂的性能,确定附加物的大致成分。第二步是在探索性实验基础上做正交实验,优选配方。本研究主要探讨了用气冲造型湿型砂来生产铁路钩缓铸钢件,从型砂的配方和型砂系统的控制等几个方面来优化其性能。高密度湿型砂对原材料的质量要求很高。首先通过对几种原砂、膨润土、粮食附加物的基本性能的检测,找出它们自身的理化性能的不同对型砂工艺性能的影响,相互组分之间的影响因素,系统的对原材料、型砂的性能进行实验,完成原材料的优化。其中重点检测了原砂的石英含量,粘土的液限值,并通过液限值确定膨润土的适宜活化量,测定热湿拉强度、湿压强度,并绘制相关的影响曲线,用差热分析曲线分析膨润土的复用性能,从中积累了大量的实验数据。另外在选用湿型砂原材料时,还充分考虑了国内原材料的质量及交通运输等多方面因素,参考了国内外高压造型线使用情况,立足于国内原材料以及对型砂基本性能的要求,试验湿型砂气冲造型的型砂配方,完成型砂的配比优化。并结合我厂的情况,试验研究了各种材料复合后的复合膨润土,以保证原材料混和均匀,克服原先加料分层现象,造成强度不均,缺陷严重,来提高湿型砂更多还原

【Abstract】 It is an economical and effective method to produce steel castings with green-sand air impact molding technology. The steel castings for rolling stock are needed in great batch and few variety, thus it is easy to manage production in series. Green-sand is easy to prepare by mixing and needs no treatments after formation. It can be poured immediately after core setting. Green-sand belongs to high density molding as shoot squeeze and static pressure such high pressure molding. It is powered by compressing air to mold in a moment. Comparing with the traditional molding technology, the sand mold is with a high moistening pressure and a even distribution of hardness. Thus the castings from green sand mold is with precise dimension, smooth surface and compaction organization. The mechanical behavior and the production rate are improved. The working conditions are improved. The air flush molding has a better distribution of hardness than ordinary high pressure molding. The part near to model is with a high hardness and the back part is with a low hardness. The sand mold is with a good conceding performance. What more, the green sand mold needs simple equipment and is very flexible to operate. The power price is very low. Thus, the future of the development and application of green-sand mold is very prosperous. Molding sand is very important to casting’s quality. Through the research on the specific object, the characters of green-sand is expected to be improved. The research paper intends to develop the advantages of air flush molding and reduce the casting defects: blow hole, sand fusion, sand cut, swelling, sand inclusion and deforming. The whole research is divided to 2 parts: a researching test shall be performed at first, in order to confirm basically the feature parametes that the molding sand should achieve. Then, add respectively new sand, bentonite, amylum, MD powder, and check the features for the molding sand to finalize the element of the additives added. Secondly, on basis of exploring experiment, do the normal experiment to select the chemical composition. This research mainly explores the production of steel castings with air flush molding green sand and the improvement of its character from the molding sand recipe and mold sand system control. The high density green-sand molding has a high requirement for materials quality. First find the different influence brought by their physical and chemical characters to the molding sand workmanship character by inspecting the characters of some kinds of original sand, betonies, and grain attachment. The influential factors of mutual component shall be found. The original materials and molding sand character shall be systematically experimented to finish the improvement of original material. Particularly the quartz content, the liquid limit of clay soil shall be inspected. By inspecting the liquid limit, the proper activation amount is defined. The moist heat pulling intensity and the moist pressure intensity shall be measured and the influence curve line will be drawn. The multiple-use character of betonies will be analyzed with differential thermal analysis curve, in result of great experiment data and experiment have been accumulated. In additional, it is found that when selecting the green-sand materials, the domestic material quality and transportation should be considered. The domestic high pressure molding application situation will also be fully considered. On the basis of domestic material and the requirements of molding sand, the experiments of green-sand air flush molding recipe will be made and the improvements of molding sand match will be finished. Associated with the situation of my manufacture, the general character of green-sand is improved by researching the compound betonies mixed with variety of materials to ensure that the materials is mixed evenly and eliminate the classification of feeding which causes the uneven hardness distribution and serious defects. Second, the effective management and control of molding sand system will be improved to improve the molding sand’character. Finally, by comparing the pouring casting substances, the casting defects such as sand fusion, sand cut, and sand inclusion are solved and the quality of products is improved.更多还原