Dynamic Modeling And Analysis On High-speed Industrial Lockstitch Sewing Machine

Industrial lockstitch sewing machine is one of the equipments, which is mostwidely used in sewing industry. With the development of high-speed, intelligence,environmental protection, dynamic performance of lockstitch sewing machine isstressed.Especially, noise and vibration reduction of lockstitch sewing machinebegin to be concerned. This article focuses on the vibration and noise problems ofhigh-speed industrial lockstitch sewing machine in dynamic simulation, test andoptimization The main contents of this paper include:Identification of noise sources, modeling and analysis for the high-speedindustrial lockstitch sewing machine. Vibration and sound pressure of the standardpoint are tested and analyzed to research the vibration and noise problems, which therotary hook mechanism, the lift teeth and transport fabric mechanism and thepuncturing and stirring mechanism of sewing machine generate. The dynamic modelof lockstitch sewing machine is established and checked to carry out dynamicanalysis. In regard to the major mechanism owning larger inertial force and,balanced assessment of the quality level is carried out to obtain the mechanism-thepuncturing and stirring mechanism, which needs to be balanced.Optimization of dynamic balance is carried out for industrial lockstitch sewingmachine. Dynamic model of puncturing and stirring mechanism is built in dynamicsimulation of mechanical system. The sensitivity of each variable on the analysistarget-RMS of the vibration force and vibration moment is analyzed. Responsesurface approximate models, which express the approximate relationship betweenthe design parameters and the analysis target, are established and verified. Thereasonable values for weight coefficients are assigned and confirmed to buildoptimal mathematical model. The optimization of sewing machine is carried out bythe means of optimizing the parameters such as mass and placement of the masscentroid of mechanism, based on MIGA. Optimized mathematical model of thepuncturing and stirring mechanism is established using MATLAB program.Optimization is carried out based on mathematical models, and the optimizationresults are compared with those based on the response surface method. Simulationresults show that the optimal design of dynamic balance for the puncturing andstirring mechanism has greatly improved its mechanical performance, such as thevibration force and vibration moment. Gap dynamic analysis for the puncturing and stirring mechanism of industriallockstitch sewing machine is carried out. Spring and damping model is used todescribe the impact of the hinge gap, and the modified coulomb model is used todescribe friction of the hinge gap. Gap dynamics model of the puncturing andstirring mechanism is established to research the institutional dynamic performancethe hinge gap impacts on. Simulation results show that the hinge gap has a greatimpact on dynamic performance of the puncturing and stirring mechanism. Thereforeit cannot be ignored in the process of manufacture and assembly.