| High-speed melt spinning winding machine play the key role in filament production process. Currently, home-made high-speed winding machine still lags far behind compared with similar overseas products, especially in the dynamic performance of the high-speed winder. As the core of the high-speed winding machine, the high-speed winder is essentially a complex high-speed thin-walled rotor system with long and thin flexible cantilever, which is mass-variable, stiffness-variable, and rotation-speed-variable. It is composed of a spindle chuck and several filament packages.As the proposed project of Shanghai Science and Technology Commission, the dynamic performance of the high-speed winder is studied in this thesis so as to provide related theoretical and technical guidance for the design of high-speed winder (the winding linear velocity is above5500m/min, the length of spindle isl500mm). Cooperation of the high-speed winding machine manufacturers is acknowledged.Theoretical modeling, dynamics simulation and experimental testing methods are adopted in this thesis in the dynamic research of the time varying system of high-speed winder. The main contents include:1. Theoretical modeling of high-speed winder considering the variable mass, variable rotary inertia and frequency-independent stiffness of "O" type rubber ring is developed by using space beam element, mass element and spring element. Moreover, an improved Newmark method is provided which is adaptable to solutions of time-varying vibration system dynamics equation.It can be concluded from the simulation that interference fit connection can be simplified as consolidation; rotating parts and non-rotating parts can be simplified as space beam element. Bearing and "O" type rubber ring can be simplified to equivalent spring and damping spring element, and packages can be simplified as the mass element. Considering the effect of shear deformation on lateral displacement and the effect of axial deformation and lateral deformation, variable mass and variable rotary inertia of package are integrated in the finite-element model which described the time varying vibration system of high-speed winder with variable mass, variable stiffness and variable rotation speed. The frequency-independent stiffness of "O" type rubber ring is considered as well. Newmark method is improved so as to adapt to the solution of the time-varying vibration dynamic equation of high-speed winder.2. Considering the gyroscopic effect and the frequency-independent stiffness of "O" type rubber ring, the time-invariant system, which describes the dynamic performance of the high-speed winder under "empty package" and "full package" condition, is analyzed, and corresponding comparison is made.It is concluded that unlike the constant system, the high-speed winder has constant natural frequencies and modes of vibration during the working process; gyroscopic effect has a greater influence on the synchronous critical speed of high-speed winder under full package state, with a smaller influence on the synchronous eddying motion critical speed under empty package state; frequency-dependent characteristics of "O" type rubber ring should not be neglected in the dynamic analysis within the scope of work of broadband speed (4547-14252r/min) of high-speed winder. The dynamic performance of high-speed winder during the entire working process cannot be predicted by analyzing a certain "fixed package state". Time varying characteristics of high-speed winder, such as variable mass, variable stiffness and variable rotation speed should be fully considered.3. Considering the time varying characteristics, such as variable mass, variable stiffness and variable rotation speed, the dynamic response of the entire working process including the high-speed winder starting from the empty package, evolving to winding at constant linear velocity (rotate at constant linear velocity and variable rotation speed), and ending at full package is calculated and simulated. The peak speed characteristics of the response are analyzed as well.When the high-speed winder starts with different isogonism accelerations under empty package, speed of frequency change of unbalance excitation has no significant effect on the critical speed corresponding to the peak value on the amplitude frequency diagram; when the high-speed winder starts up at empty package, winds at constant linear velocity and stops working at full package under excitation by unbalanced mass, the maximum unbalanced response peak speed during the entire working process corresponds to the maximum speed during the starting process at empty package. This provides theoretical verification for the fact that conducting effective dynamic balance in empty package state stables operation of high-speed winder during the whole working process.4. Conduct dynamic balance on high-speed winder with special dynamic balancing machine under empty package condition and dynamic response test analysis on high-speed winder model machine. Dynamic response test analysis of the entire processes, namely starting, stabilizing in the speed, and stopping is made. The results are verified by comparison with that predicted by the corresponding dynamic model.Critical speed of high-speed winder in empty package has been obtained in the dynamic balance experiment; this is coordinated with the theoretical calculation. Response test result shows that the theoretical analysis well predicts the effect of the speed of dynamic starting excitation, namely the angle of isogonal acceleration, on the starting response of high-speed winder under empty package. The primary reason for the vibration of high-speed winder is imbalance of the rotor system. The above experiments results prove that the theoretical model established in this thesis is accurate, effective and well explain the practical phenomenon.5. Study the relationship between high-speed winder system and primary parameters of its parts, and analyze the influence based on the relationship, then provide guidance for the design of high-speed winder after comprehensive consideration.By analyzing the relationship between the parameters with regard to the thin-walled bobbin, long and thin driving shaft, changing the position of bearing,"O" type rubber ring, the cantilever frame together other components and dynamic response of the high-speed winder, it can be concluded that the dynamic response of high-speed winder system can be improved by the following operations:1. reducing the supporting stiffness of "O" type rubber ring at the outer end of the cantilever by changing the number of "O" type rubber ring;2.increasing the wall thickness of the cantilever;3. employing carbon fiber composite instead of the thin-walled bobbin without changing the original assembly structure. Optimizing the above parameters comprehensively is better for improving the dynamic response of the high-speed winder system.Innovation in this thesis lies in:Based on variable mass, variable stiffness and variable rotation speed, a dynamic model of the time varying system of the high-speed winder including packages with variable mass and variable rotary inertia and "O" type rubber ring with frequency-dependent stiffness is developed.through analysis on the amplitude frequency characteristics of the dynamic response of of key positions of the high-speed winder in the entire working process, it is found that the maximum unbalance response peak speed corresponds to the maximum speed in the starting process under empty package, which provides theoretical basis for the fact that the high-speed winder conducts effective dynamic balance in empty package state.Study the relationship between high-speed winder system and primary parameters of its parts, and analyze the influence based on the relationship, it provides guidance for independent design of high-speed winder. By employing the carbon fiber composite instead of the thin-walled bobbin material, the supporting stiffness of "O" type rubber ring at the outer end of the cantilever frame can be reduced by changing the number of "O" type rubber ring, and the wall thickness of the cantilever can be increased to improve the dynamic response of high-speed winder system. |
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