Torque calculation for magnetic brake 4

[rogerb01]

Hello,
I have a problem regarding the correct selection of a magnetic brake to be fitted to the centre shaft of a rotating table. The table weight is 40kg. The distance from the turning axis (centre shaft) to the edge of the table is 470mm.
I am using a magnetic brake device to prevent the table from "wiping" round during manual rotation. The Brake is supplied by "HUCO" however, I need to know the max. torque generated to correctly select the brake. I would be grateful of anyone who can assist me in solving this selection problem.

 

[MikeHalloran]

The weight and location of the CG of your rotisserie table, with and without the workpiece installed, affect the torque required to rotate the table around its horizontal axis. The force applied to the workpiece while it is intended to be static is involved, too. Speaking of static, the stiffness at the workpiece may govern.

There seems to be no brake currently in the model at all. How do you intend to install the Huco brake?



Mike Halloran
Pembroke Pines, FL, USA

 

[rogerb01]

thanks for the response, with reference to the Huco brake, although it is not shown on the model. It will be fitted to the shaft and housing to give a resistance.

Thanks

 

[MintJulep]

The HUCO brakes appear to be energize to apply.

If this is the only thing holding the table in position when someone is working on the workpiece then this is not a safe arrangement as an interruption of electrical power would allow the whole thing to move unexpectedly.

For this application you need a fail-safe energize to release brake.

 

[rogerb01]

when the table is in position it will be locked off with 2 - off shoot bolts either side (not shown-sorry). Upon release of the shoot bolts the operator will manually turn the table. However a magnetic brake can be set to apply a resitance so that the table does not rotate fast subjecting the operator to a potential risk .

Thanks
ROGER

 

[alansimpson]

Anti-back drive device might help.

http://news.thomasnet.com/fullstory/27588

 

[MintJulep]

Or run the crank through a non-backdriving worm gear rather than direct.

 

[Compositepro]

Use a gearbox. It will be far safer, take care of any balance issue, and probably be cheaper.

 

[BobM3]

I think he's looking for a controlled drag. Maximum torque would be the heaviest one sided load mounted the farthest from the pivot. Say you had a 30 lb load 20 inches from the pivot, your maximum load would be 30 x 20 in 600 in-lbs. Find a brake with an adjustable output (if it's controlled drag you're after).

 

[MikeHalloran]

Agreed, the worm gearbox makes the table much safer, and brings the handwheel around to the front, making the table easier to operate and allowing multiple tables to fit end to end.

If you're still intent on using a direct handwheel and a brake, at least make it a spring- energized brake.



Mike Halloran
Pembroke Pines, FL, USA