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设计开发了3套典型盒形件微拉深模具,分别为模具Ⅰ、模具Ⅱ、模具Ⅲ,将厚度分别为100,50和20μm的3种材料分别在常温、850和950℃的温度下进行热处理,将热处理后的板料放在3种模具中进行拉深成形,研究其最大拉深力和成形深度。研究发现,微成形过程的尺度效应很明显,最大成形力和成形深度会明显减小,且不能简单用宏观成形中的相似性和类比性进行计算和解释。通过归一化处理引入尺寸比例系数λ和厚度晶粒尺寸比t/D,发现λ能够更好地解释模具Ⅰ、Ⅱ相对较大尺寸微成形过程,模具Ⅲ成形过程只能通过引入厚度晶粒比t/D才能更好地解释微成形突变现象。
Three sets of typical micro-drawing molds for box-shaped parts are designed and developed, which are mold I, mold II and mold III respectively. Three kinds of materials with thickness of 100, 50 and 20 μm are respectively carried out at room temperature, 850 and 950 ° C. Heat treatment, the heat treatment of the sheet on the three kinds of molds for drawing, to study the maximum drawing force and forming depth. The study found that the scale effect of micro-forming process is obvious, the maximum forming force and forming depth will be significantly reduced, and can not be simply calculated and explained by the similarity and analogy in macro-forming. By introducing the size ratio coefficient λ and the thickness grain size ratio t / D through normalization, it is found that λ can better explain the relatively large-size micro-forming process of the molds I and II. The forming process of the mold III can only be realized by introducing the thickness of the crystal grains Than t / D to better explain the phenomenon of micro-forming mutations.