一、绪论铸工车间的旧砂中都含有相当数量的细粉,被烧损的粘土(又称死粘土)、被烧损的煤粉或其他附加物。在旧砂回田时这些粉尘物质就都掺杂在型砂之中,虽然这些粉尘本身不产生粘结力,但是却能使型砂的湿态抗压强度提高。一般湿型铸造生产中都是根据型砂的湿态抗压强度高低而控制粘土加入量。如果型砂中含粉尘量多而含有效粘土量少也仍然显得湿态抗压强度较高,这就会使型砂中含有效粘土的数量过少,型砂的性能变脆,起模性能变 I. INTRODUCTION The old sand in the casters contains a fair amount of fine powder, burnt clay (also known as dead clay), burnt pulverized coal, or other addenda. In the old sand back to Tian these dust substances are doped in the sand, although these dust does not produce the adhesive force, but it can make the wet sand compressive strength. General wet casting production are based on the level of wet sand compressive strength and control of clay content. If the sand contains more dust and contains less effective clay is still wet compressive strength is still high, which will make the sand contains less effective clay, the performance of sand becomes brittle, moldability change