三维叠层微电极成形质量控制及台阶效应的消减

发布时间：2018-08-15 12:02

【摘要】：近年来,随着微电子、精密机械、生物医疗、航空航天等行业的迅猛发展,工业领域对微型零件的需求越来越大。微型零件的结构尺寸微小,重量较轻,因此很难用传统的机加工方法制造成形。微细电火花加工是微细加工技术的一种,该技术可加工各种超硬、脆性材料,且在加工过程中宏观切削力很小。因此,微细电火花加工非常适合微型零件的制备。在微细电火花加工中,通过微柱状电极对工件材料进行逐层扫描放电加工可获得精度较高的微结构,然而该方法存在加工效率低、电极损耗大且进给运动控制复杂等缺点。而将三维叠层微电极应用于微细电火花加工可有效解决上述问题,三维叠层微电极的制备是基于分层实体制造的一种工艺,包含线切割工位和真空压力热扩散焊工位,线切割用于对铜箔进行切割从而获得具有特定结构的二维微结构,真空压力热扩散焊将多层二维微结构按照一定的叠层顺序焊接从而拟合出三维叠层微电极。在制备含有斜面和曲面结构的三维叠层微电极时,会不可避免的出现台阶效应。针对这一问题,本文做了深入研究,主要工作和结论如下:(1)为消除纯铜箔制备的三维叠层微电极在电火花放电加工获得的微型腔中产生的接缝放电痕,基于Micro-DLOM工艺以镀锡铜箔为材料制备出三维叠层微电极。详细研究了锡膜厚度、热扩散焊温度、热扩散焊时间对微型腔表面放电痕的影响。研究表明:在锡膜厚度为1μm(厚度为50μm)、热扩散焊温度为900℃、热扩散焊时间为15 h,压强为0.127 MPa的参数下所获得的三维复合微电极连接可靠,具有良好的放电加工性能,将其应用于微细电火花加工,加工结果表面的接缝放电痕基本消失。(2)台阶效应是叠层制造中的原理性误差。通过分析可知,分层厚度是影响台阶效应的重要因素之一,分层厚度越大,台阶效应越明显。分层方向的选择也是影响台阶效应的重要因素之一,选择合适的分层方向可有效提高叠层制造的精度。(3)以镀锡铜箔为原材料制备含有斜面结构的三维叠层微电极时,在真空压力热扩散焊过程中,在压力的作用下,熔融的铜锡化合物填补了相邻单元片层之间的台阶缝隙,可有效消减台阶效应。(4)通过CAD软件设计出含有半球结构的三维微电极,分层后计算出各单元片层的二维结构尺寸。使用纯铜箔和镀锡铜箔两种材料制备了三维叠层微电极并将其应用于微细电火花放电加工。实验结果表明,通过队列电极对同一型腔进行放电加工可获得表面精度较高的微型腔。
[Abstract]:In recent years, with the rapid development of microelectronics, precision machinery, biomedical, aerospace and other industries, the demand for micro-parts in the industrial field is increasing. The micro-parts are small in size and light in weight, so it is difficult to form by traditional machining methods. Micro-EDM is a kind of micro-machining technology, which can process various super-hard and brittle materials, and the macro cutting force is very small in the process of machining. Therefore, micro EDM is very suitable for the fabrication of micro parts. In micro EDM, the microstructures with high precision can be obtained by layer scanning discharge machining of workpiece materials with microcylindrical electrodes. However, this method has the disadvantages of low machining efficiency, high electrode loss and complex feed motion control. The application of 3D laminated microelectrode to micro EDM can effectively solve the above problems. The fabrication of 3D laminated microelectrode is a process based on layered solid, which includes the position of wire cutting and vacuum pressure thermal diffusion welder. Wire cutting was used to cut copper foil to obtain two-dimensional microstructures with specific structure. Vacuum pressure thermal diffusion welding welded multilayer two-dimensional microstructures according to a certain stacking sequence to fit three-dimensional laminated microelectrodes. Step effect is inevitable in the fabrication of three dimensional laminated microelectrode with oblique surface and curved surface structure. To solve this problem, the main work and conclusions are as follows: (1) in order to eliminate the seam discharge marks produced by electrospark discharge machining, the three-dimensional laminated microelectrodes prepared by pure copper foil are used in the electrospark discharge machining. Three-dimensional laminated microelectrode was fabricated by using tin-plated copper foil as material based on Micro-DLOM process. The effects of tin film thickness, thermal diffusion welding temperature and thermal diffusion welding time on the discharge marks on the surface of the micro cavity were studied in detail. The results show that when the thickness of tin film is 1 渭 m (thickness is 50 渭 m), the temperature of thermal diffusion welding is 900 鈩，

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