地坑造型,需要铺设硬砂床。硬砂床的铺设,目前各厂都采用一种老办法,在焦炭层上铺设,铺设方法简述如下: 在地坑内,堆上一定厚度的焦炭层,从焦炭层的某一部位引出排气管,与型外相通。有的硬砂床,把型砂直接填在焦炭层的上面;有的硬砂床,在焦炭层上先铺一层草席,再在草席上填上型砂。 Pit shape, the need to lay a hard sand bed. At present, each factory adopts an old method, which is laid on the coke layer. The laying method is briefly described as follows: In the pit, a certain thickness of coke layer is piled up, and the exhaust gas is led out from a certain part of the coke layer Tube, connected with the outside. Some sand bed, the sand directly filled in the coke layer above; some sand bed, coke layer on the shop before a straw mat, and then fill the mat on the sand.