硬质合金高速磨削工艺能耗特征与表面完整性协同机理及优化研究

Cemented carbide is a sort of hard and brittle composite material which is a hybrid of hard carbide and soft metal phase. Its high speed grinding possesses some characteristics, such as time-varied grinding shock vibration, force-thermal coupling effect, etc. Currently, the researches for grinding mechanism and surface integrity on high-speed grinding of cemented carbides are still imperfect, especially few researches focusing on process energy-surface integrity synergies. Considering the complex machining characteristics of high-speed grinding of cemented carbides, this project will study process energy and surface integrity based on two aspects of grinding mechanisms. These grinding mechanisms include material removal mechanism and grinding energy consumption characteristics under the time-varied complex working condition of grinding, and heat-transfer and dissipation mechanism of the force -thermal coupled time-varied complex temperature field. Furthermore, the mapping relations among grinding factors, grinding energy and surface integrity will be established quantitatively. Based on the quantitative relations, energy-surface integrity synergies will be further researched from two aspects of force-heat grinding mechanisms. The research results have important theoretical and practical value to popularize the green and efficient cemented carbide grinding technology. Additionally, the research methodology can also be extended to other machining processes, and provide theoretical reference to the researches on energy saving optimization.

硬质合金是一种混合硬碳化物和软金属相的硬脆复合材料，其高速磨削具有时变磨削冲击振动、强力-热耦合等特点。目前针对硬质合金高速磨削机理和表面完整性方面研究仍不完善，尤其在磨削工艺能耗特征及其与表面完整性协同机理的研究几乎空白。本项目将紧密结合硬质合金高速磨削的特殊性，从时变复杂磨削工况下的材料去除机理及磨削能耗特征、力-热耦合的时变复杂温度场的热传递特性及耗散机理等方面，研究硬质合金高速磨削过程的表面完整性(表面形貌/表面及亚表面损伤/残余应力/金相组织等)和能耗特征(材料去除磨削能耗特征/能耗尺寸效应特征/顺逆磨工况下的能量耗散特征等)；探索工艺参量与表面完整性、能耗特征间的映射关系；进而建立力-热耦合的硬质合金高速磨削的能耗特征与表面完整性的协同优化机制。研究成果对推广绿色高效的硬质合金磨削技术具有重要理论和实用价值，研究方法亦可为其他制造工艺节能优化研究提供理论参考。

硬质合金材料中软金属相以及硬质相含量的不同，导致硬质合金磨削性能大为不同。其高硬度、高耐磨损的性能也使得对它的磨削加工变得非常困难。本项目将高速磨削工艺应用于硬质合金加工，深入研究硬质合金磨削机理和高速磨削的磨削机制。.项目研究了硬质合金磨削的材料去除机理及磨削能耗特征；时变复杂温度场的硬质合金磨削热量传递及耗散机理；磨削工艺能耗特征与表面完整性的协同优化三个部分内容。.研究表明：(1)实验条件下，钨钴类硬质合金的去除方式以塑性方式去除材料为主，随着砂轮线速度加大，脆性断裂去除减少。磨削比能随着砂轮线速度的增大而增加，随着工件速度和单颗磨粒最大切屑厚度的提高而减小。磨削过程中大部分磨削能量消耗于金刚石磨粒与硬质合金工件的滑擦、塑性耕犁过程，消耗在脆性断裂能和磨屑动能方面的比例较小。材料脆性越大，磨削速度对比能的影响程度越大。（2）砂轮速度对磨削温度的影响程度最大，其次是磨削深度，工件进给速度对磨削温度的影响最小。随着钴含量增加或WC晶粒度变细，温度减小。逆磨温度大于顺磨温度。热量分配比例随着砂轮线速度、磨削深度的增加和进给速度的减小而减小。随着钴含量减少或WC晶粒度变细，热量分配比例增加。基于抛物线热源模型的三维有限元仿真方法对磨削温度进行仿真可以较为准确的预测工件加工表面温度。（3）磨削用量三要素中，进给速度对表面粗糙度影响最大，磨削深度影响最小。高速磨削更有利于脆性材料的表面粗糙度降低。随Co含量和WC 晶粒度变小，表面粗糙度值减小。残余应力随砂轮线速度和磨削深度的增大而减小，随工件进给速度的增大而增大。随Co含量和WC 晶粒度的增加，残余应力σ增大。考虑能耗因素和磨削表面质量的优化方法比单纯考虑磨削表面质量的优化方法在环境可持续性上有较大优势，可以有效降低磨削能耗，从而实现节能减排。.研究成果对降低能耗、提高零件表面质量，推广绿色高效的硬质合金磨削技术具有重要理论和实用价值。