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通过对挤压铸造过程凝固和流变行为的分析,提出了密实比压、保压时间、浇注量以及挤压力4个关键工艺参数的设计准则和相应的设计计算公式。密实比压必须大于挤压合金熔点附近的流变应力与沿补缩通道流变的压力降之和,或者挤压力的有效补缩距离大于热节位置与加压位置的距离,或者热节位置(最后凝固部位)的比压始终大于零,否则就会出现收缩缺陷;保压时间约等于最后凝固位置的凝固时间与开始加压时间之和,否则会出现收缩缺陷或裂纹缺陷;浇注量必须大于考虑了金属熔体的体收缩和工艺余料的临界浇注量,同时还要小于压室的有效容积,否则会出现不能完整成形的缺陷。挤压力应大于密实压力、压头运动过程的阻力以及凝固壳发生切变流动的剪切抗力或发生拉伸流动的拉伸抗力之和,否则可能出现不能成形或存在收缩缺陷。这些准则在钢铁材料和铝合金的挤压铸造实践中被证明有效可行。
Based on the analysis of the solidification and rheological behavior of the squeeze casting process, the design criteria and the corresponding design formulas for the four key process parameters of dense and specific pressure, dwell time, casting volume and squeezing pressure are put forward. The dense specific pressure must be greater than the sum of the flow stress near the melting point of the extruded alloy and the pressure drop along the flow path of the recharging passage or the effective retiring distance of the pressing force is greater than the distance between the hot section position and the pressurized position or the hot section The specific pressure at the position (the final solidification site) is always greater than zero, otherwise shrinkage defects will occur; the dwell time is approximately equal to the sum of the initial solidification time and the start of compression time; otherwise, shrinkage defects or crack defects will occur; Must be greater than considering the body shrinkage of the molten metal and the critical amount of casting process, while also less than the effective volume of the pressure chamber, otherwise there will be incomplete forming defects. The squeezing pressure should be greater than the sum of the compact pressure, the resistance of the indenter movement and the shearing resistance of the sheared shell to shear flow or the tensile resistance of the extensional flow, or it may be impossible to form or have shrinkage defects. These guidelines proved effective in the extrusion casting of steel materials and aluminum alloys.