Workpiece locking ideas 3

[dejan95]

Hello everyone!

I have recently started my mechanical engineering (mechanical design) job. I was a handed a project of designing an assembly work station. I designed a tool which will hold my workpiece in place. The first picture bellow.

Because I was advised against using pneumatic cylinder for locking the workpiece in place (because we would like the station to be without pneumatics, only electricity), I'm searching for alternatives. I would like to use sensor which would activate the locking system (maybe electric cylinder) when the workpiece is places in the tool. The locking system would unlock once the worker would finish all operations on the part.

Do you maybe have any ideas what is the best way to lock part in place?

Picture bellow is without one part so you can see where the cylinder is supposed to fo:

 

[3DDave]

Most places would use a hand-operated clamp so that neither compressed air or electrical connection would be required. Carr-Lane and Destaco make a variety of such clamps. This saves having the sensors and controls to figure out if the worker is done.

 

[dejan95]

@3DDave

Thank you for your answer. however... I thought about hand-opereted clamps, but we actually want sensors and controls so it is not possible to take out the part until the worker has done all the operations (insert O-ring, add screws with EC...). The entire station will be carefully programmed. Because there will be a big problem if worker forgets about one operation (for instance: he forgets to put O-ring in).

I could add hand operated clamps, but i would still need a sensor to check their location, so it is not ideal.

 

[MintJulep]

Why make something so simple into something very complicated?

https://www.destaco.com/products/manual-clamping

 

[dejan95]

@MintJulep

Thank you also.

As I tried to explain earlier, locking is not primely meant to hold workpiece in place, but is meant as a safety precaution so the worker can't remove the part until all the operations are completed.

 

[3DDave]

The usual fix is to use a parts tray with controlled covers so that until a component is correctly installed the next component will not be available. Since there are apparently sensors to detect if components are installed, then sound an alarm if the part is removed before the installations are complete.

 

[Jboggs]

How will the sensor know when the operator has done all the tasks? Will the operator tell the sensor when he's done by pressing a switch? Will this sensor detect the actual presence and proper positioning of each component to be assembled? These questions all lead to a preferred method for retaining and releasing the part.

I once worked on a manual assembly station for automotive airbags. That system monitored the weight of the containers of all the individual components and would not release the finished assembly until it sensed that the weight of each component container had decreased by the right amount.

I think the "electric cylinder" you might be looking for is better known as a solenoid actuator. It could be rigged to actuate once the part is in place.

And I didn't hear a good reason to avoid pneumatics other than "because we would like the station to be without pneumatics, only electricity". Is there an actual functional reason to avoid pneumatics? Not that I'm promoting pneumatics. I'm not.

It sounds like your problem is one of sensing, not clamping. I don't understand your objection to having another sensor if you already have several sensors to detect the necessary components.

 

[dejan95]

@Jboggs and 3DDave

I understand both of suggestions. I will give the clamps another thought.

But to answer a few of your questions.

We could only install an alarm that would go off if the worker removes the workpiece before is completed, but we kind of wanted to really lock the workpiece down. And the cylinder (or clamps) would additionally hold the pice in place.

How will the sensor know when the operator has done all the tasks?

We will first have a sensor that will detect the workpiece. Than we will use a camera. Once the O-ring is placed in the worker will press a switch, and once two other parts are placed the worker will press a switch again so the camera will check the correct position. Meanwhile the EC screwdriver is already programmed so we could connect it with a cylinder and it wouldn't let go until all the screws are mounted with correct torque.
Is there an actual functional reason to avoid pneumatics?
The workstation will be on wheels so we can remove it, because it won't be used all the time. And we will already need electricity, so there is really no reason to use pneumatics just for this operation, because then we will need a lot of space and additional components.

 

[Jboggs]

"the EC screwdriver is already programmed so we could connect it with a cylinder" A pneumatic cylinder?
Sounds like you're investing a lot of money and time into this station. If so, I still don't understand the objection to installing a few fixed pneumatic quick disconnect supply stations. But whatever.

It also sounds like a fairly complex system. All this and you can't figure out how to clamp the piece with some automatic release? Sounds like you have already solved much more complex problems than that.

Investigate solenoid actuators to drive lock pins into place.

 

[GregLocock]

3DDave is describing Poka Yoke - design for correct assembly.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[MintJulep]

https://www.tlxtech.com/solenoids/one-inch-stroke-shot-bolt-solenoid

For example.

But others have given you a lot of other good things to think about.