hi, I have to use a stepper motor for lathe head stock to rotate 100 kg crank shaft with 5 rpm.wat type of motor i have to choose and what are the requirements i need.
(chapter 3 - something happened to my word) encoder,
If you really want to use a stepper for the lathe you must consider pushing up the speed of the stepper. a 18:1 ratio will give you 3600 steps per revolution if you use 1.8 deg steppers.
(slow - 300 steps per second for 5 rpm) And you will have to apply S curve acceleration deceleration to avoid stepper jumps.
The main reason why steppers wont do is the way steppers work.
At 300 steps per second a stepper will overshoot the mark and must return. having a 100kg shaft to stop and reverse would be impossible.
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Never do today what you can put of until tomorrow - Student motto
why 5 rpm means we are using this set up for crankshaft testing to check runouts etc. If it is not possible with a stepper motor give a solution suitable for my requirement.
The "testing" in a lathe changes the situation because it will not be subjected to cutting loads. (that is how i visualized the setup)
have a look at the drive for a tumbler dryer. the motor with a small pulley drives a belt running on the drum itself. )
It would be possible to use a stepper motor but I believe you have to increase the RPM on the stepper. The stepper need to be sized according to the specifications of the manufacturer.
I think a servo motor on a pulley drive with an encoder on the slow shaft would be a better option.
On both options you need a controller card capable of S curve acceleration. (start accelerating slowly and increase and also reduce the acceleration gradually as the rpm is nearing the target.
For the controller I like the Galil. A single axis for steppers and 2 axis for the servo. One axis for the servo and the other for counting.
How critical is the 5 rpm?
Can you for example run at 4.5 or 5.5?
How are you going to measure the runout?
My idea is to use the normal motor on the lathe and reduce the speed by normal selection and then fit a rotary encoder on the shaft.
The position of the shaft can then be recorded against any other digital measurement..
If you want to use a stepper the combined inertia of the lathe / shaft must be taken into account.
__________________
Never do today what you can put of until tomorrow - Student motto
Selection of Drive
Re: selection of drive
