My first automation project. Need all the help I can get. Two objectives here, one, get the job done, but two just as importantly is my learning. Thanks in advance.
Here is a schematic of what I need to do.
Shaft A is turned by another machine.
The speed of Shaft A varies a little during one job. On one job it varies from 0.25rpm to 0.6 rpm.
The speed of shaft A varies a lot between one job and the next. Most jobs are less than 4.0 rpm
There is one job in which shaft A runs at 120 rpm if this complicates this project too much I can build a second machine dedicated to that hiqh speed job.
The Lead screw, B, is the one that I need to control.
I need to control both the speed and the point at which the nut reverses direction.
The speed of lead screw B is a function of the speed of shaft A.
for example:-
job 1- B has to turn at 4 revolutions per 1 rev of shaft A.
job 2- B turns at 225 revolutions per 1 rev of A.
job 3- B turns at 11 revolutions per 1 rev of A.
Fastest that B ever needs to run is 900 rpm the slowest is 1 rpm.
I need to control the point at which the nut on leadscrew B reverses direction as a function of the number of revolutions of A.
eg.
job 1 requires reversing every 49.9 revolutions of A
job 2 reverse at 1.49 revs of A
job 3 reverse direction every 17.85 revs of A
I need a resolution of about 5 degrees of the position of shaft A at which I can set the nut on B to reverse.
Toque required to drive B under load is 0.2Nm max.
Compared to most cnc machinery, it does not need great accuracy. If the reversing of the nut is within 2 or 3 degrees of the angular position of B it would be fine and speed within 2%. Repeatability is more important. There are only 8 or so different jobs and once it is fine tuned, I just keep a record of settings for each job.
I imagine a proccessor controler where I can just set speed eg "4" for 4 revs of B per revolution of A
and 17990 degrees ( 360x50 - 10) of A at which B changes direction. When the jobs are complete the proximity switch is tripped and both A and B stop.
I am quite capable of the mecahanical side of things, have my own lathe etc. so I can easily add gearing, timing belts, pulleys etc. but I am very lacking in my electronics practice.
Questions:-
I assume a stepper motor would be best.
What sort of user interface should I aim for? I've got plenty of old computers lying around that I could dedicate to the job. A computer just seems a bit of overkill to me just for adjusting 2 parameters.
All advice is welcome
Thankyou
dam