Dynamic Analysis Of A Two-side Four-bar Beating-up Motion Of An Air-jet Loom

With the development of production, air-jet loom accounts for a large proportion of textile machinery. Compared with traditional textile machinery, the rotation speed of an air-jet loom has been substantially increased and will have more potential as the update of its components. Analysis and predicting to the dynamic characteristic of the loom under high speed is an important basis in re-design. Hence, this paper mainly focuses on the dynamic analysis of the two-side four-bar beating-up motion of an air-jet loom.Kinetostatic analysis is carried out on the assumption that all parts of the mechanism are rigid. Thus, kinematic and dynamic models of beating-up motion are set up first, and the main characteristic, such as the regularity of sley movement, reactions of kinematic pairs, input moment and shaking force/moment are studied. The effects on dynamic properties when input speed, inner diameter of hollow main shaft and the width of loom vary are also discussed. Results show that, the velocity and acceleration of sley became higher which increase the beating-up force but reduce the time available for weft insertion as the input speed raises. Reaction force, input moment and shaking moment are also increase rapidly. The change of inner diameter of hollow main shaft and the width of loom have a relatively low influence on dynamic properties. This rigid dynamics approach is especially suitable for looms with low or medium speed. While under high speed, deformation of flexible parts will affect the dynamic response seriously, as a result, the analysis of elastodynamics is needed.In the following part of this paper, the torsional deformation of main shaft and rocking shaft are taken into account, and the dynamic model is established with FEM and the flexible multi-body system method in which both the deformation and the coupling effect between deformation and large-scale movement of mechanism are considered. Minimum unknown quantities approach is used to transform differential-algebraic equations to ODES (ordinary-differential equations) which are then solved numerically with the self-adaptive Runge-Kutta algorithm. Natural frequencies of the mechanism under operating condition are then obtained. Proportional damping is introduced to instead the actual damping, and...