Research on the critical condition of Brittle-Ductile Transition about Micro-Milling of KDP crystal and experimental verification
Research on the critical condition of Brittle-Ductile Transition about Micro-Milling of KDP crystal and experimental verification
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DOI：
10.1007/s12541-015-0046-9
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发表时间：
2015-02
影响因子：
1.9
通讯作者：
Yong Xiao;Mingjun Chen;Yan-Ting Yang;Jian Cheng
中科院分区：
文献类型：
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作者：
Yong Xiao;Mingjun Chen;Yan-Ting Yang;Jian Cheng
KDP晶体是一种脆性材料，工艺参数选择不当容易导致KDP晶体的脆性畴切割。确定KDP晶体微铣削脆塑转变的临界切削深度可以指导工艺参数的选择。利用钝头球压头与脆性材料的弹塑性接触公式，阐述了微切削刃与脆性材料的接触。结合压痕临界载荷方程，建立了预测临界切削深度的计算模型。临界切削深度是工件材料特性、刀具材料特性和刀具刃口半径的函数。利用原子力显微镜测量了CBN平头铣刀的刃口半径，计算出KDP晶体材料的临界切削深度为230 nm。利用该铣刀进行了不同主轴转速和进给量下的微细槽铣削试验。结果表明，随着主轴转速的增加，微槽底面逐渐由脆性切削状态向塑性切削状态转变。临界主轴转速为30000 rpm，最大变形切削厚度为227 nm，与理论计算模型的结果相吻合。
KDP crystal is a kind of brittle material, and improper selection of processing parameter can easily result in brittle domain cutting of KDP crystal. Determining the critical cutting depth of micro-milling brittle-ductile transition of KDP crystal can guide the selection of process parameters. The elastic-plastic contact formula of blunt spherical indenter and brittle materials is used to explicate the contact of micro-cutter edge and brittle materials. Combined with indentation critical load equation, the calculation model of predicting the critical cutting depth is established. The critical cutting depth is the function of material properties of the workpiece, the tool material properties and the tool edge radius. The edge radius of CBN flat end milling cutter is measured by atomic force microscopy, and then the critical cutting depth of the KDP crystal material is calculated as 230 nm. By using this milling cutter, microgroove milling experiments are conducted with different spindle speeds and feeds. The results demonstrate that as the spindle speed increases, the micro-groove bottom surface gradually transformed from the brittle cutting state to plastic cutting state. The critical spindle speed is 30000 rpm, and the maximum deformed cutting thickness is 227 nm, which coincides with the result of the theoretical calculation model.