【作者】 张艳；

【导师】 秦旭达；

【作者基本信息】 天津大学 ， 机械工程， 2019， 硕士

【摘要】 碳纤维增强复合材料(CFRP)具有质量轻、强度高、抗腐蚀等特点。然而,由于CFRP材料的难加工特性使CFRP在加工过程中容易出现诸多加工损伤问题。相比于传统串联机器人,混联机器人具有高刚度、高精度等优点。此外,机器人切削过程中的动态特性成为影响加工质量的重要因素。因此,本文针对新型混联机器人TriMule,对不同纤维方向角CFRP铣削力建模、混联机器人动态特性、不同纤维方向角CFRP铣削加工过程中混联机器人刀尖点动态响应及其及对应的加工质量进行了研究。具体研究内容如下:(1)基于TriMule混联机器人加工平台,通过CFRP螺旋铣削实验,识别了不同切削条件下对应的切削力系数。分析发现,CFRP铣削过程中的径向、切向切削力系数可以表示为纤维切削角的三角函数,并在此基础上建立了不同纤维方向CFRP铣削力预测模型,且通过实验验证了该模型的准确性。(2)运用有限单元法、拉格朗日方程以及模态分析等理论,建立了TriMule混联机器人弹性动力学模型。在该模型的基础上,完成了对混联机器人工作空间内动态特性包括固有频率、振型以及频响函数的快速预估。同时,开展了相应的模态验证实验,结果表明理论预测结果和实验结果具有较好的一致性。(3)建立了TriMule混联机器人铣削系统的动力学模型,在此基础上分析了机器人铣削加工的稳定性。运用动态激励下的响应分析理论,研究了基于混联机器人CFRP铣削加工过程的动态响应特性。通过与五轴数控加工中心不同纤维方向角CFRP铣削加工质量的对比,研究了不同的表面质量表征指标对动态响应的敏感程度,并选取了相应的指标来评估CFRP铣削加工表面质量。基于所选指标,研究了机器人刀尖点动态响应对加工质量的影响规律。本文研究成果能为进一步提高混联机器人复合材料铣削加工质量,拓展混联机器人在航空制造业的应用提供重要参考。更多还原

【Abstract】 Carbon Fiber Reinforced Plastic(CFRP)has a lot of advantages such as light weight,high strength and high resistance to corrosion.However,difficult machining property creates a series of problems during milling of CFRP.Compared with traditional serial robot,hybrid robot presents high stiffness and good accuracy.Nevertheless,dynamic characteristics of robot during robotic milling become significant influence factors of machined quality.Therefore,the studies based on TriMule hybrid robot,focus on modelling of milling force of different fiber angles,dynamic characteristics of robot and the dynamic responses of tool center point and corresponding machined quality of different fiber angles during robotic milling of CFRP.The research content is as follow:(1)A set of experiments of UD-CFRP milling for multiple helix tools has been carried out based on hybrid robot with different fiber angle and cutting force coefficients in tangential and radical directions are calculated.The results demonstrate that cutting force coefficients can be presented as a sine function of fiber cutting angle.The force model is capable of predicting cutting forces during milling of CFRP under different fiber angle.(2)Drawing heavily on finite element method,Langrange and modal analysis theory,the elastodynamic model of TriMule robot is established.The dynamic characteristics include the natural frequencies,mode shapes and frequency response functions(FRFs)over the entire workspace are estimated in a very efficient way based on obove model.Combined with modal test experiments,we find that the dynamic characteristics obtained by the elastodynamic model have good agreement with those obtained by experiments.(3)Based on the dynamic model of robotic milling system,the robotic milling stability is studied.The dynamic response characteristics of TriMule robot during robotic milling of CFRP are studied based on theories on dynamic response analysis under dynamic loading.The sensitivity of different assessment indicators of milled quality are studied by comparing the machined quality of CFRP milling of TriMule robot and five-axis CNC machine tool under different fiber angles,and the corresponding indicators are selected to assess milled quality.Based on the above indicators,the relationships between the dynamic responses of tool center point and indicators are established.This paper can provide an important reference for improving the machined quality of CFRP milling based on hybrid robot and the application of hybrid robot in the aeronautics manufacturing industry.更多还原