众所周知,冒口的主要作用是,在铸件顺序凝固的条件下,补偿铸件在凝固过程中的体积收缩,从而获得无缩孔、缩松铸件,其次是起出气和排除夹杂物的作用。冒口设计得过小,其危害性往往容易被人们认识。因为,在气割冒口或机加工后就能发现有缩孔、缩松存在;而冒口设计得过大,其危害性往往就被人们所忽视。有人认为,冒口大保险,其实并不完全如此。在保证铸件正常补缩的条件下,冒口过大其危害性并不亚于冒口过小,首先是浪 It is well-known that the main function of riser is to compensate for the volume shrinkage of the castings during the solidification of the castings in order of solidification, so as to obtain non-shrinkage cavities and shrinkage castings, and secondly, the effect of gas extraction and exclusion of inclusions. Riser designed too small, its harmfulness is often easy to be recognized. Because, after the gas cutting riser or machining can be found shrinkage, shrinkage exists; and riser design is too large, the dangers are often overlooked. Some people think that riser insurance, in fact, is not exactly the case. Under the condition of ensuring normal casting of casting, risking too much is not less harmful than risking too much. The first is the wave