Roll case stresses
Roll case stresses
(OP)
We have a simple roll case which will have the final roll centre start to crack once the chain starts to wear. The rolls are driven by a series of double/single sprockets. There is no provision for soft start. The cause is due to the slack in the drive chain necessitating the last roll to catch up as much a 1/2 a revolution before the slack is out of the chain with the effect of a very high acceleration and thus a high force. Has anyone done any analysis on this type of situation?





RE: Roll case stresses
If I understand your description correctly, it appears that the rotational inertia of the set of rollers all react on the last roller getting it up to speed, The irresistable force meets the immovable object!
I would suggest a series of some heavy spring loaded and damped arms and idler sprockets or rollers located on the chain between the drive and driven sprockets in the roller set. This will take the static slack out of the stretched (worn) chain, so the last roller begins to move with the first roller. Note that this may place an additional accelerate-to-speed burden on your "across the line start" prime mover.
Another approach, would be to use a centrifugal mechanical or fluid clutch coupling on the last roller drive shaft to help absorb the start up energy. This approach may not be viable if the final roller speed is below that needed to fully activate the clutch to the torque required.
RE: Roll case stresses
I was wondering if anyone has done any calculations to determine the stresses in the hubs from the impact loading.
RE: Roll case stresses