【作者】 邵忠喜；

【导师】 富宏亚；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2010， 博士

【摘要】 纤维复合材料由于其高比强度、高比模量、耐烧蚀和抗侵蚀等一系列优点已经成为现代大型飞机的主要结构用材,我国启动的大飞机项目中明确规定要大量使用纤维复合材料,因此飞机复合材料零件的“高性能”制造是我们亟待解决的问题。纤维铺放技术是实现复合材料高性能制造的重要手段之一,同时也是近年来发展最快、最有效的先进制造技术。纤维铺放技术综合了纤维缠绕技术与自动铺带技术各自的优点,通过能够完成丝束夹紧、重送和切断功能的铺放头,按一定角度将预浸丝束铺放到制品表面,同时完成开口、局部加厚等功能。本文针对铺放装置结构设计、铺放控制系统、铺放轨迹规划、后置处理等关键技术进行了研究。为了提高铺放设备的加工能力,特别是为了实现复杂型面管状零件的加工,研制了七自由度纤维铺放装置,该装置由手臂、主轴和纱架三部分组成。手臂部分的三个移动轴设计成正交结构,同时为了便于机构的逆运动学分析,将手臂的手腕设计成球型手腕,其位置和姿态解耦。铺放头安装在手臂末端,能够独立控制各路丝束的夹紧、重送和切断,其结构采用模块化设计方法,按丝束运动方向分为七个功能模块:丝束导向模块、丝束夹紧模块、丝束重送模块、丝束切断模块、丝束集合模块、丝束加热模块、丝束施压模块。纱架具有张力控制功能,张力控制器设计成以交流伺服电机为执行元件,PLC为主控制器,张力传感器为反馈元件的全闭环控制系统,并采用PID数字控制技术。研究了开放式结构的铺放控制系统,该控制系统包括运动控制、丝束控制和张力控制三个部分。运动控制部分采用IPC+运动控制卡的开放式结构,铺放加工代码采用标准的G代码和M代码。通过分析单路丝束的工作循环和丝束在重送、切断、铺放状态下夹紧模块、重送模块、切断模块的工作情况,总结出丝束控制程序设计的基本原则。同时提出了两种丝束控制方法:丝束控制与运动控制整合的方法;丝束控制独立于运动控制的方法。通过对这两种丝束控制方法的比较分析,得出丝束控制独立于运动控制的方法具有方法简单、降低铺放软件开发难度的特点。最终通过铺放试验验证了丝束控制方法的正确性。分析讨论了影响相邻丝束间缝隙的三个主要因素:丝束宽度、丝束集合装置设计的合理性、丝束加热温度。研究了两种铺放轨迹规划方法,即网格化方法和UG软件的二次开发方法。网格化方法以曲面网格化数据为基础,在网格单元内计算轨迹点坐标,再将计算的轨迹点顺次拟合得到铺放轨迹。这种方法由于开发周期长、难度大,仅在算法上进行了初步研究。UG软件的二次开发方法选用UG/Open GRIP开发工具,实现了铺放轨迹、轨迹规划坐标系下铺放头压辊姿态、轨迹点丝束数量、纤维重叠面积与间隙面积等铺放信息的计算。通过分析等铺放角曲线的计算方法、等距偏置算法、曲线延伸算法、基于丝带边缘曲线的轨迹规划方法,提出以等距偏置算法为计算核心的铺放轨迹优化方法,该轨迹优化方法使铺放设备尽量处于满丝铺放状态,减少了剪切丝束的次数,有助于铺放工作效率的提高。通过分析铺放运动过程,采用位姿分离法研究了七自由度纤维铺放设备的后置处理算法。铺放运动由主轴旋转运动和铺放头运动共同完成,因此将七自由度铺放机构分成主轴和手臂两部分分别进行后置处理,而这两部分都是非冗余机构,从而避开了处理冗余机构的运动学问题,简化了后置处理算法。通过分析主轴旋转变量的计算方法,提出了基于手臂末端运动轨迹和基于手臂末端施压方向的两种后置处理算法,并对这两种算法进行比较,得出基于手臂末端施压方向的后置处理算法具有机床工作平稳、关节变量范围小、关节角波动小、适用范围广的特点。因此对于曲率半径小、曲率变化大的铺放轨迹首选该后置处理算法。最后通过铺放运动仿真试验和机床铺放试验验证了后置处理算法的正确性和有效性。更多还原

【Abstract】 Fiber reinforced composites have become major structural materials where attractive strength-to-weight and stiffness-to-weight ratios, ablative resistance, corrosion resistance are the significant advantages. China has been launched the aircraft project which need lots of fiber composite material, so the high-performance manufacture of composite parts of aircrafts is an urgent problem. Fiber placement technology is a key method of producing composite structures, which is also the fastest growing and most efficient composites manufacturing technology. Fiber placement technology is the combination of filament-winding and tape layer technology, including tows clamp, restart, cut, the placement head moving on the mould surface at specific angle, local clipping and thickening function. The research of thesis is focused on structure design of fiber placement machine, composition and structure of CNC, path planning, post processing and so on.In order to improve the production capacity of the equipment, especially realize complex surface tubular parts producing, the fiber placement machine has been designed. It consists of three major parts: manipulator, spindle and creel cabinet. The three shifting axis of the manipulator are orthogonality due to simplify the inverse kinematics analysis of mechanism. The style of wrist is orthogonal spherical wrist and position decoupling with orientation. The fiber placement head is mounted on the end of the manipulator, including guide module, clamp module, restart module, cut module, compaction module, collection module and heat module, which can achieve independent control of tows clamp, restart and cut. The creel cabinet has the function of tension control. Utilizing PID digital control technology, the tension controller using AC servo motor as actuator, PLC as controller and tension sensor as feedback component is closed loop control system.This paper studied open architecture CNC system of fiber placement machine, which include motion control, tow control and tension control. Motion control using IPC and motion control card is open architecture. G code and M code is written in a standardized mode. Through analyzing operating cycle of single tow and operating mode of clamp, restart and cut module in tows restart, cut and fiber placement working condition, fundamental principle of program designing is proposed. Comprehensive approach of tows control and motion control is presented together with independent approach of tows control and motion control. Comparing two control schemes, the second scheme is convenient, and the software development is easy. Finally the experiment results show that this method is correct and adjacent tows gap influenced by width of tow, design rationality of tow collector and heating-up temperature of tows.This paper studied meshing method and secondary development of UG which are used to path planning. Meshing method based on meshing data of curve surface. Coordinates of track points are calculated in mesh cells and these points are connected from first to last to form trajectory. This method is long development cycle and difficulty, which is just carried out a preliminary study for algorithm. Secondary development of UG using UG/Open GRIP realizes calculation of path, posture and quantity, overlapping area and gap area of tows. Through analyzing equivalent placement angle method, iso-metric offset method, natural extension of curve method and path planning method based on the tows edges, a path optimization based on iso-metric offset method is proposed. This method make the machine in total tows states and reduce cut frequency, the utilization rate of equipment is improved thereby.Through analyzing the fiber placement process, the paper utilizes pose-separated method to study the processing algorithm of 7-DOF fiber placement machine. Fiber placement process consists of rotational motion of spindle and motion of fiber placement head, so 7-DOF fiber placement machine is divided into two parts, the spindle and the manipulator. These two non-redundant parts are postprocessed separately. Using this method, the kinematics problem of redundancy mechanism can be avoided and post processing algorithm is simplified. After analyzing the different algorithms of spindle rotary variable, the post processing algorithms based on motion trajectory of end-effector is proposed together with the post processing algorithms based on compressing direction of end-effector. Through analyzing two algorithms, the second one is smooth working reliable, small variation range of joint variable, small ripple of joint angle and wide range of application. For placement path of small radius of curvature, the pressing direction algorithm of end-effector is being used. The simulation and experiment results show that the method is correct and effective.更多还原