高孔率泡沫金属的孔结构保形铣削加工研究

Investigation of Milling Process of Foam Metal with High Porosity for Pore Structure Protection

为避免高孔率泡沫金属的孔结构在加工过程中变形,提出一种利用填充材料进行泡沫金属固化后再进行孔结构保形铣削加工的新方法。首先对不同填充材料的泡沫铜进行铣削加工试验,然后利用SEM图进行表面形貌分析,选用孔径保形率、孔嵴保形率以及透气性来评价泡沫金属铣削加工的保形效果。基于中心组合试验,以孔径大小和0.7 kPa压力下的流量值为指标,建立二次回归方程并计算出在选定填充材料条件下的泡沫铜的优化加工参数。研究结果表明,以氢化松香-硬脂酸钠按质量比4:1混合的固化填充材料可以使得泡沫铜在铣削加工过程中获得较好的保形效果。孔径保形率、孔嵴保形率以及透气性性能均随主轴转速、进给速度呈先增加后降低的趋势。同时,在选择优化填充材料的条件下,主轴转速为311 r/min,进给速度为165 mm/min时,铣削加工泡沫铜具有较好的保形效果,其孔径保形率可达96.3%,且在0.7 kPa的压力下,流量值达7.36 L/min,具有较好透气性,实现了具有较好保形效果的泡沫铜的铣削加工过程。

To protect the pore structure of foam metal in the machining process,a new milling method is proposed that different filling materials are used for solidification of pore structure.Taking copper foam as an example,the milling experiments are performed with different filling materials and processing parameters,and then surface morphology is analyzed based on the SEM results.Conformal rate of pore structure and pore crest as well as the permeability are used to evaluate the processing quality of milling process of foam metal.Using a central composite experimental design method,the quadratic regression equations are established to obtain the optimized milling parameters based on the pore size and the flow rate at fixed pressure of 0.7 kPa.The results show that better conformal effect is obtained with the hydrogenated rosin and sodium stearate at a ratio of 4:1.With the increase of cutting speed and feed rate,the conformal rate of pore structure and pore crest as well as the permeability are firstly increased and then decreased.Moreover,when the optimized processing parameters with a cutting speed of 311 r/min and a feed rate of 165 mm/min are adopted,conformal rate of pore structure of 96.3%,flow rate of 97.5%with the pressure of 0.7 kPa and better permeability are obtained.In this way,the best conformal effect is obtained with optimized filling materials in the milling process of foam metal.