我厂单体铸造活塞环已有十多年历史,下面就这些单体环气孔、夹渣、砂眼和冷隔等缺陷的鉴别、成因和防止方法作一初步探讨。 一、气孔 单体活塞环的气孔主要有两种,即单个集中气孔和针孔。单个集中气孔比较容易辨认,多数发生在活塞环铸件的表面上,一般在浇口对面附近出现,大多数出现在活塞环的内侧一边,它需经冷加工后才能发现,往往在环表面孔径较小,而向内渐大,用针插入小孔,可以观察到有相当深度。一般情况下,平环的针孔比油环多,而平环的针孔大多出现在环的内侧底面。 活塞环毛坯的单个集中气孔主要是侵入气体,侵入的气体一般是水蒸汽、一氧化碳和氮气等。活塞环凝固很快,浇注时由于铸型中的水分蒸发和有机物的挥发形成大量气体,一部分气体通过透气的砂型逸走,一部分气体就可能进入合金液体中而形成单个集中气孔。 防止单个集中气孔的方法是:控制型砂水分,在型砂中加入少量的煤粉,提高浇注温度以及降低合金成分中的含硫量。 针孔属于反应性气孔,是液态金属的某些成分之间,或液态金属与铸型之间发生化学反应产生气体造成的气孔。这类气孔中的气体多为一氧化碳和氢气,它们是如下反应的产物: I plant casting piston ring monomer has more than 10 years of history, the following on these monomer ring pores, slag, blisters and cold defects such as the identification, causes and prevention methods for a preliminary discussion. First, the pores Single piston ring pores are mainly two, namely, a single focus on the pores and pinholes. Single concentrated pores are easier to identify, most of them occur on the surface of the piston ring castings, generally appear near the gate opposite, most appear on the inside of the piston ring side, it needs to be found after cold work, often in the ring surface smaller aperture , And gradually inward, with the needle into the hole, you can observe a considerable depth. Under normal circumstances, the flat ring pinhole than the oil ring, and flat ring pinhole mostly appear in the ring inside the bottom. The single concentrated pore of the piston ring blank is mainly invading gas, which is usually water vapor, carbon monoxide and nitrogen. Piston ring solidification fast, pouring due to the evaporation of water in the mold and volatile organic matter to form a large number of gas, part of the gas escape through the gas-permeable sand, some of the gas may enter the alloy liquid to form a single concentrated pores. To prevent a single concentrated pores are: control of sand moisture, adding a small amount of pulverized coal in the sand to improve the pouring temperature and reduce the sulfur content of the alloy composition. Pinholes are reactive pores, which are the pores created by the chemical reaction between certain components of the liquid metal, or between the liquid metal and the mold. Most of the gas in these pores is carbon monoxide and hydrogen, which are the products of the following reactions: