Kinematic And Dynamic Modeling And Analysis Of The Critical Components For Flat Sewing Machine

As one of the most applied sewing machine, flat sewing machine has great effects on the improvement of garment technology as well as people’s life. And the research on its application remains to be further studied.Firstly, the introduction of different types, application and progress trend of flat sewing machine are described in this paper both domestic and abroad. Then one type of flat sewing machine is taken for example to establish the 3-D model of its main structures, thread take-up and needle bar mechanism, feeding mechanism, rotary shuttle and thread hook mechanism, stitch length adjusting device mechanism with the help of SolidWorks.Secondly, on the basis of mechanical principle, the structures of thread take-up and needle bar mechanism and feeding mechanism are simplified into different modules. Then the motion principle with workflow is deeply analyzed according to the kinematic sketch of the mechanisms. The kinematic and dynamic models both of the thread take-up and needle bar mechanisms and the feeding mechanism are deduced as well as the kinematic and dynamic equations based on the closed-loop vector method and the simultaneous constraint method. Applying the Simulink module built in the Matlab, the Simulink simulation model of the mechanisms are built and executed according to the real situation. The kinematic parameters and the kinematic pair force with the inertia force of all motion components are obtained from the simulation.Through the analysis of the kinematic parameters, the paths of the thread take-up point and the feeding tooth are displayed, which like a piece of willow leaf and ellipse. By analyzing the kinematic parameters of each linkage and the forces in kinematic pair in the mechanisms, the conclusion can be made that there is a periodic force which likes an impact force acting on each kinematic pair. And the periodic forces will cause the rack’s vibration as well as the abrasion of the kinematic pairs.Finally, in order to clarify the working principle and the specific structures of rotary shuttle and thread hook mechanism, stitch length adjusting mechanism, the kinematic sketches of both mechanisms are drawn through AutoCAD.The analysis for the main structures of the machine based on the dynamic static analysis method laid a foundation for the further improvement of sewing machine. Depending on the CAD software interface, the digital design of industrial sewing machine had been demonstrated.