超高速磨削风冷结构设计与流场分析

发布时间：2018-07-17 20:30

【摘要】：超高速磨削指的是砂轮线速度在150m/s以上的磨削加工技术，由于其加工效率高、加工表面质量好以及可加工超硬材料等优势，近年来取得了快速的发展。伴随着磨削过程产生的大量磨削热易造成工件烧伤，为提高表面质量，通常采用高压冷却液方式向磨削区供液，这种冷却方法效率低、成本高且对环境污染大，由于超高速磨削时的气流屏障，真正进入磨削区域的磨削液比例低，冷却效果差。此外，由于窄深槽固有的结构特性以及磨削液的粘滞性，使其难以对磨削区进行充分冷却。因此，需要设计适用于窄深槽磨削的新型高效冷却方式。新型CBN具有很好的热传导性能，可有效降低传入工件的磨削热，进而使得工件表面的温度大幅下降。为研究开发适用于单层CBN砂轮高效深磨的新型冷却方式提供了基础。本文结合传统干磨削的理念，提出适用于超高速磨削尤其是高效深磨的砂轮风冷结构设计方案，并对设计结果进行了流场分析。主要的研究内容包括：（1）基于传统磨削时对砂轮气流屏障研究的方法，对窄深槽磨削时砂轮周围的气流分布情况进行了仿真分析，分析得出砂轮厚度、砂轮线速度、砂轮直径、砂轮表面粗糙度以及窄深槽尺寸等5个因素对气流场分布的影响，同时阐述了高效深磨时移动热源建立的原则，，为后续多场耦合验证风冷式砂轮结构的冷却效果和优化设计奠定了理论基础。（2）根据外置喷嘴冷却方式进行冷却时各个参数对磨削冷却效果的影响，提出了适用于内风冷砂轮出风口设计的理论，即以工件表面换热能力最大为目标确定砂轮基体和卡盘上出风口的尺寸，根据空气动力学基本理论确定弧道形式。在流量确定的情况下以最大压升为目标函数设计卡盘上的涡扇叶片结构用来产生高速气流。（3）在流场分析软件中，完成对风冷式砂轮结构的环境建模，分析其冷却效果，并对风冷式砂轮结构的涡扇叶片结构和出风口结构分别进行流场分析，为下一步分区域的优化设计提供参考。
[Abstract]:Ultra-high speed grinding refers to grinding technology with linear speed of grinding wheel above 150m/s. Because of its high machining efficiency, good surface quality and machinability of superhard materials, it has made rapid development in recent years. In order to improve the surface quality, high pressure coolant is usually used to feed the grinding area with a large amount of grinding heat produced by grinding process. This cooling method is of low efficiency, high cost and high pollution to the environment. Because of the airflow barrier in super high speed grinding, the ratio of grinding fluid entering grinding area is low and the cooling effect is poor. In addition, due to the inherent structural characteristics of narrow deep groove and viscosity of grinding fluid, it is difficult to fully cool the grinding area. Therefore, it is necessary to design a new high efficiency cooling method suitable for narrow deep groove grinding. The new CBN has good heat conduction performance, which can effectively reduce the grinding heat of the imported workpiece, and make the surface temperature of the workpiece drop significantly. It provides the foundation for the research and development of a new cooling method suitable for high efficiency deep grinding of single layer CBN grinding wheel. Based on the idea of traditional dry grinding, this paper puts forward a design scheme of air-cooled structure for super high speed grinding, especially for high efficiency deep grinding, and analyzes the flow field of the design results. The main research contents are as follows: (1) based on the traditional method to study the airflow barrier of grinding wheel, the distribution of air flow around the grinding wheel during narrow and deep groove grinding is simulated and analyzed, and the thickness of grinding wheel and the linear velocity of grinding wheel are obtained. The influence of five factors, such as the diameter of grinding wheel, the surface roughness of grinding wheel and the size of narrow deep groove, on the distribution of air flow field is discussed, and the principle of establishing moving heat source during high efficiency deep grinding is expounded. It lays a theoretical foundation for the subsequent multi-field coupling verification of cooling effect and optimization design of air-cooled grinding wheel structure. (2) the influence of various parameters on grinding cooling effect according to the cooling mode of external nozzle. A theory suitable for the design of the air outlet of the inner air-cooled grinding wheel is put forward, that is, the size of the air outlet on the wheel matrix and chuck is determined with the aim of maximum heat transfer capacity on the surface of the workpiece, and the form of the arc channel is determined according to the basic theory of aerodynamics. With the maximum pressure rise as the objective function, the vortex blade structure on the chuck is designed to produce high speed airflow. (3) in the flow field analysis software, the environmental modeling of the air-cooled grinding wheel structure is completed. The cooling effect is analyzed, and the flow field of the blade structure and the outlet structure of the air-cooled grinding wheel are analyzed respectively, which provides a reference for the optimization design of the next sub-region.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG580.6

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