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我厂铝活塞铸造采用底注上抽芯式金属型重力铸造。由于活塞头部、顶部与裙部壁厚差大,加上形状复杂。此工艺只考虑加工方便,没有完全符合顺序凝固要求,使活塞产生以同时凝固为主、顺序凝固为辅的冷却方式。为了使活塞得到充分补缩,一般使用一对粗而大的冒口,其结果是浇冒口重量与活塞本体重量的比为1～2:1左右;模温高,延长浇注周转时间;质量也不够稳定。从1987年起,我厂开始进行微型保温单冒口铸造工艺试验,经过几年来的摸索和实践,证明这种工艺是可行的。现已在我厂6只主要品种上批量和小批生产。并且采用保温冒口后,活塞得到充分补缩,铸造质量稳定,经检验活塞宏观、金相及机械性能匀符合GBI148—82《内燃机铝活塞技术条件》。最为突出的是既保证了质量,又减少了浇冒口系统与活塞毛坯的重量比,提高了工艺出品率和班产,经济效益显著。
Our factory aluminum piston casting using the bottom note on the core metal gravity casting. Due to the piston head, the difference between the top and skirt wall thickness, coupled with the complexity of the shape. This process only consider the processing convenience, does not fully meet the requirements of the order of solidification, so that the piston at the same time the main coagulation, the order of solidification, supplemented by the cooling method. In order to make the piston fully refueling, the general use of a pair of coarse and large riser, the result is the ratio of pouring riser weight and piston body weight of about 1 to 2: 1; mold temperature is high, extending casting turnaround time; quality Not stable enough either. From 1987 onwards, our factory began to carry out miniature insulation single riser casting process test, after several years of exploration and practice, that this process is feasible. Now in our factory 6 major varieties on the batch and small batch production. And the use of thermal riser, the piston is fully compensated, casting quality and stability, the test piston macroscopic, metallurgical and mechanical properties are in line with GBI148-82 “internal combustion engine aluminum piston technical conditions.” The most prominent is not only to ensure the quality, but also reduces the ratio of pouring riser system and the weight of the piston blank, improve the production rate and class production, significant economic benefits.