Motor output - 90 degrees? 1

[monkeys]

hello all,

I was wondering if someone can help me out.

I am wanting to use a motor/gearbox for rotating an arm ,keyed onto the gearbox output shaft, 90 degrees - i.e 90 degrees is the max i require - how do i acheive this?

thanks,

CAllum

 

[byrdj]

Depends greatly on motor type.
with simple DC motor, one way would be use limit switches (LS) and mechanical stops (MS) at each extreme of arm. for example, LS-1 wired to interupt motor CW rotation when arm hits 90 degrees MS and LS-2 wired to interupt motor CCW rotation when arm hits 0 degrees MS.
another way would be design and make a "servo driver". Install Rotary linear differtail transformer (RVDT)position indicator, compare desired angle signal to RVDT position, use error to develop DC current to drive DC motor.

for stepping motor, its driver can be programed for desired motor revolutions

 

[DRWeig]

Callum,

Look into direct-coupled electric actuators by Belimo, Johnson Controls, Honeywell, Kele. They're made for dampers and are easy to set up for 90-degree rotation. Pretty inexpensive too. Torques up to 300 in-lb. For higher power, industrial valve actuators are available, or you can stack the direct-coupled ones together on a shaft.

Best to ya,

Old Dave

 

[MintJulep]

How fast, how much torque, what happens after you reach 90 degrees, how accurate do you need to be?

90 degrees is the max you need. Do you need precise locations between 0 and 90?

Do you really need a gearbox? A crank and lever mechanism could be designed to provide 0 to 90 to 0 cycle from a continuously rotating motor. Companies like Camco and Fergusson (sp?) make neat magic boxes that will do that as well.

 

[monkeys]

thanks for your replies.

The motor/gearbox spec is as follows: 3rpm, 260Nm

The process is automatically loading tools on a plate into a press. The arm tilts down 90 degrees and an electromagnet locks onto the plate and the carriage with the arm is mounted to drives in (using another motor - rack/pinon driven).

Once the press is loaded the magnet disengages and the arm moves back and then the arm tilts up to let the next piece load.

I will have a look at this "magic box" idea.... any direct links handy?

The current design is using a motor/gearbox connected to the arm which tilts - and drives until it hits a limit. I am currently working on the next fail safe - ( i.e. if the first limit fails the 2nd limit will come into play) and then if these two swithces are not made a physical stop is hit with trips the overload on the motor.

I just thought there must be a simplier idea - i.e. the motor can go fully around but the arm only ever rotates 90 degrees.....

callum

 

[MintJulep]

seems to be a distributor:

http://www.camcoindex.com/ID_Roll.htm

 

[monkeys]

thanks for the link mintjulep.

I will have a look to see if i can find anything that will do the job.

thanks again,

Callum

 

[zekeman]

Try a 90 degree geneva mechanism or a slot and crank mechanism where and you don't have to get the rotation of the crank all that accurate.You oscillate the crank using limit swithes on the crank arm.

 

[tygerdawg]

seems like a good application for a pneumatic rotator and slide

TygerDawg