Positioning a rotating basket precisely to the same position each time
Positioning a rotating basket precisely to the same position each time
(OP)
I need to align a very large round basket lid precisly at the same spot within 0.25 inches every time. This is in an industrial environment with water, chemcials, heat, fiber, ...etc. Lids presently may be cocked in the top of the basket as much as 1.5 inches therefore elevation is not the same all the way around the outer perimeter. The baskets sit on a turntable and rotate until correct position is found. I presently use a proximity device looking for a raised sensing block that is very unreliable.
What type of non-contact sensor may be employed to sense when the lid is properly aligned?
What type of non-contact sensor may be employed to sense when the lid is properly aligned?





RE: Positioning a rotating basket precisely to the same position each time
is there a mechanical or electrical brake that stops (whichever is rotating)it on the desired spot? you might be able to get away with the existing proximity by slowing down the speed as it approaches the target point...thereby it won't overshoot....
a use of stepper motor is a possibility but it will be quite an investment...
dydt
RE: Positioning a rotating basket precisely to the same position each time
If you need more accuracy both Honeywell and Allen-Bradly had linear CCD sensors which could be used in conjunction with a fluourescent tube for this type of application. (I'm uncertain if they still market them.)
RE: Positioning a rotating basket precisely to the same position each time
Is the lid hinged and you simply need to stop the basket accuratly?
Is the lid unatached and not relivent to the basket location?
If you will provide more information we will be glad to help.
RE: Positioning a rotating basket precisely to the same position each time
Good luck,
John Schrock
www.glubie.com
RE: Positioning a rotating basket precisely to the same position each time
Cameron Anderson
Sales & Applications Engineer
Aerotech, Inc
St. Paul, MN
www.aerotech.com
"Dedicated to the Science of Motion"
RE: Positioning a rotating basket precisely to the same position each time
There is a VFD driven brake motor on this system that does slow down when approaching the sensor.
RE: Positioning a rotating basket precisely to the same position each time
Several questions arise. How do you align the dogs with the slots, or as I suspect do you simply lower the lid into the basket and rotate the basket through 360+ degrees so that somewhere the dogs will be in allignment with the slots?
If this is the case can you not use two or three (or more) air cylinders to press the lid into its horizontal position and hold it there until the rotation is complete? I'm not sure about air cylinders but I do know that Parker made hydraulic cylinders with integral encoders which could be used for position sensing. This approach could also be used here for confirmation that the lid was fully inserted into the pot.
RE: Positioning a rotating basket precisely to the same position each time
....a proximity switch, inductive or capacitive can survive harsh environment...from dust, grease, powder, ink, etc....imagine an operator running a machine....called an electrician at 2 AM because a simple machine won't run because somebody blocked a photoeye accidentaly....
...everytime we have to design or modify a system in our plant...we always try to "idiot proof" it....sorry for the word but it is true.....
dydt
RE: Positioning a rotating basket precisely to the same position each time
TTFN
RE: Positioning a rotating basket precisely to the same position each time
I think you mentioned using an inductive proximity switch on the lid which indicates that it is metallic.
Inductive proximity switches are also available in analog output types and are very accurate in measuring distance to a ferrous part. They have been used in saw mills to monitor blade sharpness. A dull blade has a slight side to side excursion not seen in a sharper blade.
Your total range of possible lid position may be outside the range of the sensor and thus cause a possible problem with the lid hitting the sensor, but might be worth a look.
Good Luck