发动机缸体加工多尺度误差流建模理论与协调控制方法

Automobile engine block has been characterized by mass production, quick takt time, and absolute interchangeability of machining accuracy. Selection assembly mode has been cancelled using Macro error control method. However, high-precision engine block requires high-accuracy assembly to simultaneously consider the effect of Micro-Meso surface morphology including waveness, surface roughness and etc. Thus lack of Macro-Meso-Micro multi-scale error regulation methodology is becoming a bottleneck for absolute interchangeability of high-precision engine block. This project aims to develop a new multi-scale error stream theory for engine block based on its multi-scale error transition features associated with the multi-stage manufacturing processes. Macro-Meso-Micro error separation algorithm and its digital representation will be researched to identify the multi-error model and formation mechanism for typical processes of milling, boring, and honing. Based on the unified form of multi-scale error model, error transition and reflection mechanism resulted from engine block’s installation and relocation will be investigated to extend traditional Macroscopic error stream to Multi-scale error stream model by considering dimension, shape, position, waveness, and surface roughness. Normal and inverse solutions for the multi-scale error model will be explored to reveal the error transition and cumulative law for typical manufacturing features such as cylinder block bore and axle hole. This project will establish a new methodology for error diagnosis, compensation, and coordination control by multi-stage experimental validation in cylinder block multi-stage machining processes. This project will also provide a theoretical foundation for absolute interchangeability of high-precision automotive engine.

汽车发动机缸体制造批量大、节拍快、加工精度要求完全互换。缸体宏观几何误差（尺寸、形位等）的控制已取消分组选配，然而高精度装配需要考虑缸体介/微观表面形貌（波纹度、粗糙度等），宏/介/微观多尺度误差综合控制是发动机高精度高效率制造的瓶颈。本项目从缸体加工误差的“多尺度”和“多工序”传递特征出发，建立缸体加工多尺度误差流理论。研究表面宏/介/微观误差分离算法和数字化表征，揭示缸体铣、镗、珩磨等基本工序的多尺度误差模式及其形成机理；借助于多尺度误差的统一数学描述，研究缸体装夹重定位误差传递与加工误差复映机制，将传统的宏观尺度误差流模型扩展到考虑尺寸、形位、波纹度、表面粗糙度的误差流模型；研究多尺度误差流方程的正逆求解方法，揭示缸孔、轴孔等关键特征多尺度加工误差的传递与累积规律，形成缸体多工序加工误差诊断和协调控制新方法并进行实验验证，为实现缸体加工从分组装配向完全互换转变提供理论基础。

缸体是汽车发动机的核心部件，其加工精度直接关系到缸孔-活塞、主轴孔-曲轴、缸体-缸盖等零件的配合，对摩擦功、密封性、泄漏等发动机性能有着关键影响。缸体的加工过程由数十道复杂工序构成，多工序下误差不断引入、传递、累积，最终引起缸孔、缸体顶面等关键特征的多尺度误差。研究不同加工工艺下多尺度误差的形成机理，引入误差流思想对缸体多工序加工过程进行误差综合协调控制，是提升发动机缸体加工质量的重要解决方案。. 本研究提出了适用于缸体的多尺度误差流建模理论，围绕缸体特征表面铣削、镗削、珩磨等基本加工工艺，解决了高清晰测量数据多尺度误差分离、单工序下工艺参数综合影响、多工序加工过程误差传递建模、多工序误差协调控制等关键问题，准确揭示了各类加工参数对缸体宏微观多尺度误差的影响、传递和控制规律，实现了宏微观精度综合预测和基于发动机缸体几何特征和质量成本均衡的多工序加工误差协调控制新方法。开发的相关计算工具与试验手段为实现面向完全互换的缸体加工精度保证技术提供理论方法支撑。