Multi-quality torsion system of bridge crane transmission

- Jan 09, 2018 -

Bridge crane transmission is a multi-quality torsion system. However, both theoretical calculations and experimental measurements show that, in order to estimate the maximum load calculated by the mechanical strength, it is generally said that the simplification of a transmission mechanism to a dual-mass single-degree-of-freedom system has met the requirements of engineering accuracy. In order to solve the problem is simple, but also the damping omitted.

 


The bridge crane transmission mechanism is reduced to the differential equation of motion of double mass single degree of freedom system. Due to the relative coordinates quoted, the degree of freedom of a two-mass system becomes one. The form of the equation solution depends on the form of excitation and resistance torque changes. Bridge crane resistance torque can generally be considered unchanged. The form that changes over time depends on the characteristics of the prime mover.


Multi-quality torsion system of bridge crane transmission


If the drive is AC Wound Motor, the general starting torque is linearly reduced with the increase of the speed of the mechanism; if the motor is driven, then the start of the mechanism is to rely on the clutch. At this time, the driving torque increases with the increase of time, and the time of increase depends on the speed of the clutch. In order to simplify the technology of the dynamic load of the overhead crane mechanism, it can be regarded as a step, that is to say the mechanism is subjected to a certain dynamic torque at the start moment and then it remains unchanged.


 

Since the torsional vibration of the rotating system has a high natural frequency, the torque of the torsional vibration reaches a maximum value for a short time, which is usually one-tenth or one-twentieth of the starting time of the mechanism.

 


Therefore, assuming that the bridge crane in the short period of time and the same incentive force caused by the error is not large, for AC wound-type motor, according to this assumption to estimate the load is too large. When the agency starts up with a friction clutch, it grows in a straight line. If you press the motor speed change, you can get more accurate results.


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