Pneumatic actuated drop-away work location?

[cc22288]

Hey all,

My company takes in-house extruded aluminum and makes heatsinks out of them. Sometimes the saw cuts arent close enough and we need to mill both sides of a part. Currently, they use extra material on the sides they want to mill, and then they use a dowel pin in a tool holder in the carousel that the program calls up and positions to locate parts in a repeatable fashion. Then when the tool changes the pin is gone and you can then use an end mill to cut the part to size.

SO.

I inherited a mess of bad programming and setup procedures that im systematically going through and fixing. Im trying to get away from using vises and vise jaws, making custom fixturing for each part. What I'd like to do is include moveable work stops into the fixturing. I'm thinking pneumatically actuated. Do any of you do something like this? Any advise to what might work? Z position isnt critical, so im thinking something like flange mounted linear ball bearings and a air cylinder linear actuator to push the pin up and retract it?

Thoughts?

 

[IcarusMW]

from my perspective, you might be over-complicating this. why not just keep using the vises and probe each piece to determine the center, then cut from there?

 

[cc22288]

I wish that was an option. None of our machines have work probing. I've gotta make lemonade out of lemons.

 

[CarbideBob]

....

Thoughts?

My thought is that I'm having a hard time picturing what you are trying to do.
A zillion ways to make a locating shotpin.
Not sure if this of any help.
McMaster-Carr

 

[cc22288]

Yes this sorta thing is along the lines if what I want to do. More compact tho. Im actually working on something spring loaded that pops out of the bottom of the fixture and pushes down to lock it back in now... not sure if itl work..

 

[cb750chris]

That seems way more complex than necessary. I would just put a recessed drill bushing in the fixture and use a matching slip fit dowel pin to locate on. Pull the pin after the part is clamped down. Easy, simple, cheap, repeatable. If you're worried about chips in it go for a larger dia for easy clean out and/or drill the hole through to allow chips and coolant out the bottom.

Sent from my SM-N960U using Tapatalk

 

[vegard]

I would make sure that there is no way for the operator to leave the stop up…. Or it will happen. Maybe a flip up stop that is spring loaded down, so that the operator must hold it up during loading…

 

[CarbideBob]

I would make sure that there is no way for the operator to leave the stop up…. Or it will happen.

For sure, always assume this. Everyone makes mistakes.
Do the "Can my dog run this even if a rabbit runs out to distract her".... or the secretary comes out wearing oh-my.
Again do not understand the system. Does this locator need to change or is one fixed datum okay over a range of part sizes.
Spring loaded pin in a drill bushing moved up by a air cylinder with a wedge at 90 is easy and gets you a few thou. and not much installed height.
If that pin needs different X for different parts now how to move it easily and to the right setting.
Bob

 

[Radar987]

Currently, they use extra material on the sides they want to mill, and then they use a dowel pin in a tool holder in the carousel that the program calls up and positions to locate parts in a repeatable fashion. Then when the tool changes the pin is gone and you can then use an end mill to cut the part to size.

Okay... and what's wrong with the current method?

Im trying to get away from using vises and vise jaws, making custom fixturing for each part. What I'd like to do is include moveable work stops into the fixturing. I'm thinking pneumatically actuated.

How is this better? You lose the existing failsafe by adding a new failsafe that isn't as failsafe. Then aside from having to build a bunch of fixtures, you'll need to find some place to store them.

What exactly is it you're trying to accomplish?

 

[CarbideBob]

Okay... and what's wrong with the current method?

Wondering the same.
Not super fast and uses a slot in the tool-changer but seems workable.

 

[Mud]

I would make sure that there is no way for the operator to leave the stop up…. Or it will happen. Maybe a flip up stop that is spring loaded down, so that the operator must hold it up during loading…

SPI used to sell exactly that. They work great.

 

[Brian]

Pretty much any CNC router uses pneumatic shot pins for location. Just a simple air cylinder and you locate against the shaft when it is in the up position. Use a spare m-code and a pneumatic relay and you can automate the process so it never gets left in the up position.

 

[Tonytn36]

Festo and most other manufacturers make cylinders specifically for use as stop cylinders. Most cylinders do not have the side loading force capability for this. The stop cylinders have a front bushing designed for side loading.

 

[cc22288]

That seems way more complex than necessary. I would just put a recessed drill bushing in the fixture and use a matching slip fit dowel pin to locate on. Pull the pin after the part is clamped down. Easy, simple, cheap, repeatable. If you're worried about chips in it go for a larger dia for easy clean out and/or drill the hole through to allow chips and coolant out the bottom.

Great suggestion. I just dont trust the operators to not leave the pin in unfort.

 

[cc22288]

Okay... and what's wrong with the current method?



How is this better? You lose the existing failsafe by adding a new failsafe that isn't as failsafe. Then aside from having to build a bunch of fixtures, you'll need to find some place to store them.

What exactly is it you're trying to accomplish?

I suppose I didn't think of it that way. Thats why I like posting here, because another set of eyes is always helpful. You're showing me an angle i hadnt considered. Storage for fixturing is not an issue, we have a large warehouse.

 

[lionelt]

Great suggestion. I just dont trust the operators to not leave the pin in unfort.

Maybe that was the reason the stop pin is in the tool changer now, to prevent accidents?

 

[cc22288]

Could very well be.

 

[doug925]

SPI used to sell exactly that. They work great.
View attachment 327872

We have one of those too.
When you need a swing away stop, that one works well.

Doug