非均质骨组织高效低热损伤磨削的新方法

With the increase of bone tissue diseases and the rise of orthopedic surgery and minimally invasive surgery, bone grinding is widely used in surgery. The large heat generation in grinding process is the key factor that influences the safety for clinical application. A new method, a combination of numerical simulation and experimental study, is proposed for thermal control in bone grinding process, which involves the improvement of diamond grinding tool and the optimization of cooling method. The main research contents are as follows: (1) By combination of brazing and orderly arrangement of diamond abrasive techniques, a new method is proposed for manufacturing medical diamond grinding wheel with optimal performance, in the terms of the arrangement type of diamond grains and traits of solder bond. (2) Heat transfer mechanism of mist cooling in grinding contact zone and the influences of different nozzles on the cooling performance are both discussed, which contribute to develop a new and safe cryogenic spray cooling technology for bone grinding process.(3) An accurate heat transfer model of heterogeneous bone grinding process is established; this model is used to obtain the complete temperature field under different grinding conditions and is further verified by related experiments. This project reflects the multidisciplinary cross-integration. The results will be helpful to solve the thermal control problem and reduce risk of thermal injury in bone grinding process.

随着骨组织疾病日益增多以及整形、微创手术的兴起，骨磨削技术在外科手术中应用广泛。磨削过程的高产热量是影响该技术安全应用于临床中的关键问题。本项目拟采用数值模拟与实验研究相结合的方法，从改进金刚石磨具性能和优化外部冷却方式等角度提出面向骨磨削过程热量控制的新方法并进行可行性研究。主要研究内容包括：（1）融合钎焊技术和金刚石磨粒有序排布技术，从磨粒有序排布方式和钎料结合剂性状方面，探索获得最佳磨削性能的医用金刚石磨轮制造方案；（2）研究低温喷雾冷却下磨削接触区的换热机理，讨论不同喷嘴布置方式对冷却性能的影响，为骨磨削过程开发医用安全型低温喷雾冷却系统；（3）建立准确的非均质骨磨削过程传热模型，获得不同磨削条件下骨磨削的完整温度场，并进行相关实验验证。本项目体现了多学科的交叉融合，其成果将有助于解决骨磨削热量难以控制的技术难题，为有效降低骨磨削热损伤风险提供有力支撑。

骨磨削是神经外科、整形外科和骨伤科常见的和基本的手术操作之一，磨削过程产生的热量会对骨组织及邻近的脑神经和血管结构等关键组织带来热损伤，神经细胞出现热损伤的温度阈值仅给43℃。针对上述问题，本项目提出从改进金刚石磨具性能和优化外部冷却方式两方面来降低磨削过程的产热量及其对生物组织的热损伤影响。项目研究的重要成果如下：.（1）面向骨磨削的新型钎焊金刚石磨头研制：针对微型球状金刚石磨头，设计了新型的磨粒有序排布方式，并基于钎焊工艺和磨削理论优化了单元磨轮上磨粒的状态要素和空间分布要素。采用钎焊磨粒有序化排布砂轮和电镀磨粒无序化排布砂轮进行骨磨削的初步对比实验表明，采用钎焊工艺和磨粒有序排布技术可一定程度上降低磨削温度，从而在源头上降低骨磨削的产热量。.（2）医用安全型低温喷雾冷却系统研究：建立骨磨削加工实验系统和低温喷雾冷却系统，采用内埋式热电偶测量磨削温度。经冷却条件下的骨磨削实验研究发现，从磨具的切入侧布置喷嘴能保证冷却液有效进入磨削区。在相同的工况下，低温喷雾冷却（温度为3℃，流量为200-300ml/h）下热电偶测得的温升总体比滴灌冷却（温度为22℃，流量为800ml/h）低4℃。.（3）基于传热学反问题建立骨磨削过程传热模型：建立了骨磨削过程的三维瞬态有限元热分析模型，通过构造磨削区热流密度的瞬态分布函数，利用顺序函数法（SFSM）与序列二次规划（SQP）耦合的传热学反问题方法，对磨削区瞬态的热源强度及分布参数进行同时反演，并对喷雾冷却条件下骨磨削温度场进行重构。仿真结果表明，采用低温喷雾冷却技术能够明显抑制43°C的热损伤边界向磨削槽两侧及下方扩散。