一、问题的提出 工农—16型背负式喷雾器的开关壳(图1),以黄铜铸件加工而成。对其锥孔与开关心的配合要求高密封性,有一定的强度和耐磨性,不允许有气孔、缩孔等铸造缺陷。在大批量生产时,铸件尤应有较好的铸造工艺性和切削加工性。 First, the question put forward Worker-peasant-16 knapsack sprayer switch shell (Figure 1), made of brass castings. The tapered hole and the opening and closing of the heart with high sealing requirements, there is a certain degree of strength and wear resistance, does not allow pores, shrinkage and other casting defects. In mass production, the casting should have better casting processability and machinability.