【作者】 邵丁伟；

【导师】 周杰；

【作者基本信息】 合肥工业大学 ， 材料加工工程， 2006， 硕士

【摘要】 本文结合江淮汽车厂4DA1型发动机缸体、缸盖的生产实际,对覆膜砂及其泥芯的各种性能进行了较为广泛而深入的研究,并采用热重分析方法对其机理进行了有益的探索,得到了以下的粗浅认识: 所研究的北方覆膜砂A为70/40目的四筛砂,粒度较粗且粒形圆整,具有典型的风砂特征。该覆膜砂还具有较高的熔点(99.6℃),采用这种砂制造泥芯,更有利于防止铸造缺陷的产生。 在覆膜砂常规固化温度(200℃～250℃)和固化时间(90s～140s)范围内,固化温度和固化时间对覆膜砂泥芯的发气性影响不大,在确定覆膜砂泥芯制备的固化温度和固化时间参数时,可主要以强度高低作为选择的依据。 三种覆膜砂的固化强度都表现为随固化温度或时间的改变,先不断升高直至达到最大值,然后再不断下降的基本规律,但鉴于B砂和A砂分别对固化温度和固化时间较为敏感,在生产中应该分别对温度和时间加以严格控制。 泥芯的固化强度达到最大值后,进一步升高固化温度或延长固化时间都会使强度下降。而TG曲线表明该强度的下降主要是由于其高分子粘结膜产生部分化学键的断裂所致。 溃散性试验和TG分析结果表明,三种覆膜砂表面的酚醛树脂均在500℃以上产生分解,从而使泥芯产生“溃散”。受700℃加热的泥芯,溃散率为100%。 三种覆膜砂的最佳固化参数分别为——覆膜砂A 230℃、110s,覆膜砂B 230℃、120s,覆膜砂C 220℃、120s。更多还原

【Abstract】 The thesis is based on the production of cylinder body and head of JiangHuai automobile company. After studying the performance of resin coated sand, we can get the following simple results:The resin coated sand A is rougher and more uniform and rounder, it belongs to the typical wind-sand, moreover its melt-point is lightly higher than B and C, as a result of this, it is preferable to be used as the priority of making the sand-core and to prevent the all kinds of defects from happening.The curing-temperature and curing-time have little effect on the gas-permeability property of the resin coated sand during the constant curing-temperature and the curing-time, which are between 200 degree centigrade and 250 degree centigrade and between 90 seconds and 140 seconds respectively. So it’s not necessary to consider it when we make sure the parameters for the production of sand-core.The strengths of three kinds of resin coated sand all begin to increase until the utmost and then begin to decrease while changing the factors of curing. But it’s necessary to control the time and the temperature strictly during the production, because B resin coated sand is sensitive to the curing-temperature and A is sensitive to the curing-time respectively.When their strengths all reach the peak, they begin to decrease while increasing the temperature or prolong the time. The curves of thermogravimetric analysis show that the above results are caused by the breakage of chemical links.The experiment of breaking the ranks and the thermogravimetric analysis show that the phenol formaldehyde resin begins to decompose when the temperature is above 500 degree centigrade, which make the sand-core break the ranks. When they are heated to 700 degree centigrade, the rates of breaking the ranks can reach 100 percent.The optimal curing-parameters of three kinds of resin coated sand are respectively that A is 230 degree centigrade and 110 seconds, B is 230 degree centigrade and 120 seconds, C is 220 degree centigrade and 110 seconds.更多还原