Research On Key Technology Of Fiber Placement Machine

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.