铝合金用覆膜砂型(芯)界面背压测量方法的研究

Measurement Method of Interfacial Back Pressure of Coated Sand Mould(Core)for Aluminum Alloy

设计了一套对浇注时覆膜砂型(芯)界面背压测量的气体采集的试验装置,并对测量方法进行了优化。研究了浇注温度、覆膜砂发气性、金属液静压头高度、砂芯长度对测量结果的影响。结果表明,最大界面背压和峰压时间随着金属液浇注温度的上升而上升,随着覆膜砂发气量的增加而上升;金属液静压头高度不足时气体会以气泡的形式进入金属液从而降低界面背压;随着砂芯长度的增加,最大界面背压显著上升。其中砂芯长度对界面背压的影响大于覆膜砂发气性对界面背压的影响,可见对于气孔类缺陷来说,最关键的是铸件结构对其的影响,因此降低气孔类缺陷的最佳方案是设置合理的排气系统。

A set of testing apparatus was designed to measure the interface back pressure of coated sand mold(core)during pouring through the gas pressure acquisition system,and the measurement method was optimized.The effects of casting temperature,gas emission of coated sand,height of metal hydrostatic head and length of sand core on the measurement results were investigated.The results indicate that the duration of maximum interface back pressure and peak pressure is increased with the increase of pouring temperature and gas production of coated sand.When the height of the metal hydraulic static pressure head is insufficient,the gas enters the metal liquid in form of a bubble,thus reducing the interface back pressure.The maximum interfacial backpressure is obviously increased with the core length increase,where the influence of core length on the interface back pressure is greater than that of the gas-emissim of coated sand.,proving that the most critical factor for porosity defects is casting structure,and the optimal scheme to reduce porosity defects is to set up a reasonable exhaust system.