kamenges
Member
I have an application where I am camming a rotary axis to a master axis driving a web material. The cam profile is fairly simple. The axis is a tucker so it interacts with the web in one location on the web in a given cycle and repeats indefinitely. It needs to interact with the web at web speed but can them slow down and speed up as necessary to tuck in the correct location the next cycle based on the product length. For those of you who know, this is very similar to a rotary knife application.
My question has to do with motor heating on the longer product lengths. Once the cycle length it longer than roughly twice the tucker circumference I have a choice to make. I can either stop the tucker axis 180 degrees away from the tuck position to allow web to pass and then restart the axis to engage the web at the desired location. However, I could also let the axis overshoot the 180 degree position, back up an identical distance on the other side of 180 degrees then continue on with the move tuck for the next cycle. This would work for lengths up to just shy of 4 times the tucker circumference, which gets me past the longest length I have to deal with.
Is there a motor heating benefit to be gained by using one profile over the other? In the end the motor is managing the same amount of energy in either case. In one case it is using higher torque but has a near zero torque during dwell. In the other case it is using lower torque but it never stops. I think the only way it matters is if servomotors experience increasing or decreasing percentage losses as a function of torque.
Any ideas would be appreciated.
Keith
My question has to do with motor heating on the longer product lengths. Once the cycle length it longer than roughly twice the tucker circumference I have a choice to make. I can either stop the tucker axis 180 degrees away from the tuck position to allow web to pass and then restart the axis to engage the web at the desired location. However, I could also let the axis overshoot the 180 degree position, back up an identical distance on the other side of 180 degrees then continue on with the move tuck for the next cycle. This would work for lengths up to just shy of 4 times the tucker circumference, which gets me past the longest length I have to deal with.
Is there a motor heating benefit to be gained by using one profile over the other? In the end the motor is managing the same amount of energy in either case. In one case it is using higher torque but has a near zero torque during dwell. In the other case it is using lower torque but it never stops. I think the only way it matters is if servomotors experience increasing or decreasing percentage losses as a function of torque.
Any ideas would be appreciated.
Keith