Optimization of gear transmission mechanism of detaching roller for comber
Objective With the increase of combing speed,the internal excitation frequencies of the hybrid-driven gear transmission mechanism of the comber detaching roller will increase.When it approaches the natural frequencies of the transmission mechanism,the mechanism will have resonance,causing damage to some components.Therefore,in order to master the dynamic performance of the transmission mechanism and avoid resonance,it is necessary to study the influence of the change of mechanism parameters on the inherent characteristics and then optimize the design of the transmission mechanism.Method A hybrid-driven gear transmission mechanism of the comber detaching roller was designed.The lumped-mass method was adopted to establish the natural frequency model of the transmission mechanism,and the excitation frequencies of the transmission mechanism at different comber speeds were calculated.Then,the sensitivity model of the natural frequency of the transmission mechanism to moment of inertias was obtained by derivative method.Finally,by optimizing the number of teeth of each gear in WW differential gear train of the transmission mechanism to change the moment of inertia,the first order natural frequency was increased.Results The natural frequencies of the transmission mechanism were divided into two types according to the number of multiple roots:single root frequency and N-1 multiple root frequency.With the increase of the number of double planetary gears,the single root frequencies changed,while the N-1 multiple root frequencies were independent of the number of double planetary gears.When the speed of the combing locomotive was 300,400 and 500 nips/min,the internal excitation frequency of the transmission mechanism did not intersect with the natural frequency,and the mechanism operated normally without resonance.However,when the speed of the combing machine was increased to 600 nips/min,the meshing frequency of the gear pair c-d intersected the first order natural frequency(points A and B),and the mechanism may resonate at these two points.Then,the first order natural frequency decreases with the increase of the moment of inertia of each component.Among them,the first order natural frequency showed the highest sensitivity to the moment of inertia of planetary gear p,and was almost insensitive to the moment of inertia of planetary carrier h and gear b.With the increase of the rotational inertia of planetary gears p and q,the first order natural frequency was decreased rapidly at the initial stage and then decreases gently.With the increase of the rotational inertia of sun gear s and a,the first order natural frequency was decreased gradually with almost constant slope.After parameter optimization,the first natural frequency of the transmission mechanism became 1 259.28 Hz,43.44%higher than the original,which would avoid the intersection of the internal excitation frequency and the natural frequency of the mechanism when the combing locomotive speed was raised to 600 nips/min,ensuring that the transmission mechanism operates normally without resonance.Conclusion The method of concentrated mass is adopted to establish the natural frequency model of the hybrid-driven gear transmission mechanism of the comber detaching roller.The relationship between the natural frequency and the excitation frequency of the transmission mechanism under different comber speeds are calculated,and the number of teeth of each gear of WW differential gear train in the transmission mechanism is optimized according to the sensitivity analysis.Further experiments will be carried out in the future to promote the progress of combers.
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