Research On Slider-crank Mechanism Dynamic Characteristics Of Needling Machine

Needling machine is an important equipment of dry-woven textile industry, its core components were two symmetrical slider-crank mechanism, the longitudinal inertia force of the slider can not be completely eliminated when the machine was working, which resulted in vibration and noise, and the needling machine’s life would be greatly reduced, and the health of workers would be affect, and the failure frequency would appeared more than before, and the product quality would be reduced.In order to improve the frequency of needling machine further, we are urgent to need to study its vibration problems. In this thesis,slider-crank as the research object to study it. From four major areas to analysis vibration phenomenon, inculding the law of motion of the needle beam member, force analysis, computer modal analysis and harmonic response analysis, the vibration waveform of the bent axle and needle beam member (time waveform analysis and spectrogram analysis) to identify the reasons may cause vibration.First of all, proceed from the motion characteristics of the slider-crank mechanism, draw a graph of the main part of the movement of the slider-crank mechanism to identify the cause of the vibration may cause motion curve. Secondly, the use of powerful analysis features of ANSYS to calculate the main components of a slider-crank mechanism such as rods, the amount of deformation of the crankshaft, and experience being required stress, according to the amount of deformation to find out the cause of the vibration may cause. Again, using ANSYS software analysis important component of the slider-crank mechanism:crankshaft, connecting rod, needle beam including modal analysis and harmonic response analysis to identify important component such as natural frequencies and vibration model resonance,vibration amplitude and phase. Finally, using the test equipment produced by Jiangsu Donghua Test Technology Co., Ltd. test slider-crank mechanism on the site, draw the main location of the vibration waveform and spectrogram to identify the reason of the vibration based on the measured vibration waveform and spectrogram Comprehensive analysis of the theoretical movement curve and the results of the computer simulation and actual measured vibration signal, then found out the reason of the vibration.Through movement curve theoric analysis and ADAMS dynamics simulation found that relatively large impact on the movement of the slider-crank mechanism of needling machine, which will cause equipment vibration may affect product quality and reduce the life of the machine. Fortunately, select appropriate the quality and centroid distance of the balance block will be able to minimize the force of inertia, inertia force of the slider-crank mechanism can not be completely eliminated, reducing the force of inertia we need to reduce the slider and rod weight, and the distance and the length of the linkage. The largest amount of deformation of Linkage is the Z direction, the largest stress that linkage endure is much less than the allowable stress; Then calculated the largest amount of deformation of the crankshaft within allowed limited, and found crankshaft torsional stress is much smaller than its reverse allowable stress. By means of ANSYS software by modal analysis and harmonic response found connecting rod resonance phenomenon occurs around frequency40HZ, the crank will resonance phenomenon occurs around30HZ, the first10of the needle beam natural frequency of maximum is2.1561HZ,however,the speed of needling machine will soon across the resonance region of the needle beam, so improve needling machine vibration characteristics we can consider needle beam factors as secondary factors in the future, and the maximum operating frequency of the needling machine is20HZ,which will not cause a resonance phenomenon of the slider-crank mechanism. Through test the vibration of the Slider-crank mechanism on the spot, and analysis of its filtered vibration signal waveform and spectrogram obtained that the vibration of slider-crank mechanism mainly due to rotor imbalance and rubbing.Finally, the paper presents three different optimal ways, the first is drawing a slider theoretical acceleration curve graph, by means of changing acceleration parameter to reduce the value of acceleration significantly. The second is by conversion of a different elastic modulus, damping coefficient, the friction coefficient to replace the better the material in the process of ADMAS simulation, which turn acceleration curve to be relatively smooth to avoid the impact force generated Finally, installed the flywheel and counterweight block and re-installation of the crankshaft and the rocker device to test vibration, vibration amplitude was reduced to three to five times.