I am looking to improvise on a current mechanical design that locks spherical bearings in particular position by tightening of screws. The spherical bearings are usually in locked position and are disengaged only while carrying out calibration. I intend to incorporate automatic locking mechanism maybe by using some sort of push-pull solenoid that disengages locking during calibration.

PS: All the parts are machined in aluminum.

Need your suggestions on mechanical design of such system and selection of an appropriate solenoid that optimal locks spherical bearings for stability. Your expert advice on these aspects is highly valued.

 

Use magnetic lock:
https://web.archive.org/web/20170329100815/http://www.sdcsecurity.com/docs/whitepapers_emlocks.pdf
https://en.wikipedia.org/wiki/Electromagnetic_lock

 

Use magnetic lock:
https://web.archive.org/web/20170329100815/http://www.sdcsecurity.com/docs/whitepapers_emlocks.pdf
https://en.wikipedia.org/wiki/Electromagnetic_lock

Can you give me a reason why you suggested this? Why not a solenoid?
Does magnetic lock not create a disturbance to the calibrated bearings?

 

I am looking to improvise on a current mechanical design that locks spherical bearings in particular position by tightening of screws. The spherical bearings are usually in locked position and are disengaged only while carrying out calibration ie., ( when bearings are under calibration an actuator need to unlock by pushing the front part ) I intend to incorporate automatic locking mechanism maybe by using some sort of push-pull solenoid that disengages locking during calibration.

PS: All the parts are machined in aluminum.

Need your suggestions on mechanical design of such system and selection of an appropriate solenoid that optimal locks spherical bearings for stability. Your expert advice on these aspects is highly valued.

 

Hi S,
Can you use a cam?
C

 

The amount of force that will probably be required to lock-up the Bearings is probably
far greater than the force of any "practically-sized" Solenoid.

Even a Gear-Motor driving a Fine-Threaded-Screw would be an "iffy" proposition,
and might be quite a bit larger and heavier than what You might be envisioning for your Project.
Not to mention, expensive,
and the requirement of hard-Threaded-Brass-Inserts that won't gall and bind after the first 3 uses.

You gave no Size, or Weight, or Electrical-Power, or Force, requirements.
.
.
.

 

The amount of force that will probably be required to lock-up the Bearings is probably
far greater than the force of any "practically-sized" Solenoid.

Even a Gear-Motor driving a Fine-Threaded-Screw would be an "iffy" proposition,
and might be quite a bit larger and heavier than what You might be envisioning for your Project.
Not to mention, expensive,
and the requirement of hard-Threaded-Brass-Inserts that won't gall and bind after the first 3 uses.

You gave no Size, or Weight, or Electrical-Power, or Force, requirements.
.
.
.

Hi L,
Don't you think there would be enough force in a solenoid moving a cam?
C

 

I question the wisdom of using aluminum in any friction clamping scheme, because it has a tendency to bind. To be more specific, I have not seen a satisfactory arrangement with aluminum on aluminum, other than disposables.

 

The amount of force that will probably be required to lock-up the Bearings is probably
far greater than the force of any "practically-sized" Solenoid.

Even a Gear-Motor driving a Fine-Threaded-Screw would be an "iffy" proposition,
and might be quite a bit larger and heavier than what You might be envisioning for your Project.
Not to mention, expensive,
and the requirement of hard-Threaded-Brass-Inserts that won't gall and bind after the first 3 uses.

You gave no Size, or Weight, or Electrical-Power, or Force, requirements.
.
.
.

The statement was quite clear that the desire is to UNLOCK the bearings for adjustment during calibration. So probably only a very small amount of motion is needed, but a great deal of force will be required. The mechanical arrangement needed to produce the high force short motion effect is not a suitable application for aluminum.

 

I question the wisdom of using aluminum in any friction clamping scheme, because it has a tendency to bind. To be more specific, I have not seen a satisfactory arrangement with aluminum on aluminum, other than disposables.

It can be changed to other materials like delrin.

 

The statement was quite clear that the desire is to UNLOCK the bearings for adjustment during calibration. So probably only a very small amount of motion is needed, but a great deal of force will be required. The mechanical arrangement needed to produce the high force short motion effect is not a suitable application for aluminum.

Hi S,
Can you use a cam?
C

due to space constrains CAM may not be implementable.

 

Use the screws with geared stepper motors to tighten and loosen them.

 

Maybe this mechanism, as found on injection molding machines, can be adapted for your application.

 

If not simply motorizing the existing screws I think I would be inclined to use pneumatic cylinders in the fashion of air brakes. The clamping is constant by springs, the pneumatic cylinders act against the springs when the bearings need to be freed.

 

Hi S,
Can you use a cam?
C

due to space constrains CAM may not be implementable.

 

The amount of force that will probably be required to lock-up the Bearings is probably
far greater than the force of any "practically-sized" Solenoid.

Even a Gear-Motor driving a Fine-Threaded-Screw would be an "iffy" proposition,
and might be quite a bit larger and heavier than what You might be envisioning for your Project.
Not to mention, expensive,
and the requirement of hard-Threaded-Brass-Inserts that won't gall and bind after the first 3 uses.

You gave no Size, or Weight, or Electrical-Power, or Force, requirements.
.
.
.

Thank you for your detailed feedback and insights! I appreciate the points you’ve raised about the force requirements and potential issues with using a solenoid or gear-motor for my project.

Size dimensions are provided in the attached snapshot.
Matrial: aluminum
force required is to push the front plate by at least 2mm.

 

I question the wisdom of using aluminum in any friction clamping scheme, because it has a tendency to bind. To be more specific, I have not seen a satisfactory arrangement with aluminum on aluminum, other than disposables.

It can be changed to other materials like delrin.

 

There is much missing information here, like how much force/torque these spherical bearings are supposed to resist when locked?
When unlocked, how much "drag" friction is acceptable?
How much power is available?
The solution lies in the definition of the problem.

But I suspect a solenoid would not be a good choice.