1　问题的提出　　 2 0 0 0年江动集团研制出一种新型单缸柴油机 ,缸盖铸件由专业生产缸盖铸件的公司铸造二厂承担。由于时间紧 ,来不及制作成套金属模具 ,于是采用了桐油砂砂芯。但由于缸盖的内部结构复杂 ,砂芯最薄处只有 5ｍｍ ,最厚处有 2 0ｍｍ ,再加上桐油砂的性能不够理 1 The Proposed Problem Jiangdong Group developed a new type of single cylinder diesel engine in 2000. The cylinder head castings are undertaken by the Company’s foundry No.2 factory specialized in producing cylinder head castings. Due to the tight schedule, too late to make sets of metal molds, so using tung sand sand core. However, due to the complicated internal structure of the cylinder head, the thinnest sand core is only 5 mm and the thickest is 20 mm. In addition, the performance of tung oil sand is not enough