以前谈到过,用粘土湿型砂造型时,无论采取什么造型方法都不可能使型砂的颗粒作紧密排列。而且,为了保持较好的拔模性能、防止膨胀缺陷、避免铸件热裂,我们也希望铸型中砂粒不作紧密排列。可是,事物总是有两重性的。我们在某一方面所希望的情况,也会在另一方面带来麻烦。这里,我们就是要讨论砂粒排列不紧密而带来的麻烦。 As I mentioned before, it is not possible to arrange the granules of the sand closely in any modeling method with clay wet sand. Moreover, in order to maintain better draft performance, prevent expansion defects, and avoid hot cracking of the castings, we also hope that the sand grains in the mold will not be closely aligned. However, things always have duality. What we hope for in one area will also cause trouble on the other. Here, we are going to discuss the inconveniences caused by the tight sand arrangement.