In-die part transfer system for very small parts

Hi Robin,

I hope I understand the problem.

I'm a former Toolmaker and later design draftsman and I did a lot of design work on progressive dies. Since you can't use a strip feeder, what about a walking clamp using the press stroke as the means of indexing the clamp?

I would have a slide mounted at the pull end if there is enough scrap left after the processing to pull it through. If not then obviously the push end is the only other option.

In that slide, I would have a flat bar with two vertical rods. I'd then have a sliding bar of similar proportions that slides on the two rods. Finally at the top of the rods, another fixed bar to mount a DA cylinder to move the middle bar as a clamp on the material.

I would use mechanical indexing by the press stroke to slide the bar/rod/assembly back and forth so it is alway sin sync. Finally have the DA cylinder activated to clamp and un-clamp as needed. That way any discrepancy between clamping and un-clamping will not be relayed to the material positioning.

Dave

Rob> I'm not sure how many toolmakers we have here but here goes anyway. >

I'm not familiar with the term "walking clamp".

This die is very similar to a progressive die, although it lacks a strip. Right now, they have about twenty parts inside the die at any one time, all lined up. Is that what you were picturing?

Does this mean a "walking clamp" would be required for each operation? (about a dozen plus another half dozen idle stations) I was thinking of a single set of rails (with parts nests for each station) running the length of the die. This adds complexity during tryout, but machining is likely reduced. A complete clamp/transfer assembly for each station would increase machining time, but reduce tryout complexity. Hrm.

Thanks for responding.

Regards,

Robin

It's great to utilize scrap, but this may not work. If this is a long term contract and you are considering a new die anyway, go with coiled stock, decoiler and straightener, run the part through on a strip or skeleton. The process you describe sounds like a headache, but I can't think of a good solution.

Hi Robin,

I think I am with Ron on this one. Maybe forget the scrap approach.

The term "walking clamp" means it walks along with the material it is transferring. It is actually sliding, but usually referred to as walking. Picture cutting wall stud timber to length as they come out of the shaper. The cut off saw is on a slide that is moving at the same speed as the timber emerging, "walking" along with it. At the appropriate time, the saw is pushed through the timber and the slide returns to the start ready to cut the next length. This allows the cut to be made without stopping the timber flow.

If I have your problem clear, then you should only need one walking clamp. I suspect you need to find a tool and die designer as this should be a fairly straight forward issue for them. I can foresee other problems for you though, keeping parts where they need to be for the impending press stroke, especially without a strip. Not impossible just more complexity added.

However, maybe trying to utilize the scrap has more drawbacks than benefits if the issue might be more simply solved with available technology on-site by using strip.

Dave

Robin, a transfer press seems like it might work.

-matt

Dave and Ron,

This is an automotive application for a T3 suppler. Axing the scrap means the die goes back to the bidding process. At 20k parts/week, it would be nice to not have to buy new material.

I think we're mostly on the same page. You mean having a single walking clamp moving all the parts over one station between strokes? That's basically what I had in mind.

Unfortunately the current die was designed by a die designer (*NOT* a die MAKER!) and he made a real mess. Broke lots and lots of basic rules which he would know had he built dies in the past (I'm a bit ranty about this after hearing about it for about six months from my roommate who's building/trouble shooting this monster).

For sure. A major problem with the current die is that the designer decided to advance the parts through the die by pushing the first one along and loading another. As in, there's a SA cylinder pushing about twenty parts through the die by hammering the first one in the line. You can imagine what a mess. I'm pretty sure this is the root cause. This shop does mostly prog dies and they would have had no problems had it been running off a strip.

I guess the info I'm really looking for is examples of how to do this in a smaller applictaion. I've seen transfer presses run for larger parts (like 6"+ dia) but this part is about 1.5"dia and they've already bought the press (which accomodates a prog die easily enough, but adding a transfer system is another issue). Things like whether to use a cam-driven transfer as opposed to some type of servo system. Whether it's possible to use two or three large die sections, or if fully individual stations are required (like large transfer dies).

This inquiry is mostly a mental exercise as well as a favour (some favour!) for a friend...

Thanks for your time guys.

Regards,

Robin

Matt,

The rail and nests are exactly what I was thinking about. It's nice to see an actual example. I'm quite sure they won't spring for a new press, but hopefully this type of die can be run on a conventional press.

I'd say the biggest issue is transfering the parts without having them fly away due to the speeds involved (something like 50spm). This is esspecially an issue if the rails are cam-driven. Dave's idea of the clamp is probably a requirement. I think typical transfer presses merely lift the parts, relying on gravity to keep them on the fingers on the rail (I'm no expert) but I don't think that would fly here.

Thanks for posting that link.

Regards,

Robin

"Robin S." wrote in news:1158857713.806422.18670 @m7g2000cwm.googlegroups.com:

Robin, Not sure what you are doing to the parts as far as the operations performed, but a vacuum system on the transfer rail might work as a clamp during transfer.

Anthony,

That's a very interesting idea. There isn't a lot of scrap around the finished part, but I wonder if it would be enough to hold them.

I think they use venturi effect mechanisms to hold body panels in the robots in tadem press lines, although I could be wrong. I wonder if enough flow and vacuum could be created to deal with the speeds involved, given the wee size of the suction area.

Definitely something to consider. Thanks.

Regards,

Robin

Robin,

Years ago I built an automation machine that required small suction cups. The smallest cups I could find where by William B. Rudow Co.

Jon

"Robin S." wrote in news: snipped-for-privacy@h48g2000cwc.googlegroups.com:

Robin, We use vacuum quite a bit for part transfer. Festo makes several solutions for the vacuum generation. The most common we have is just a little (25mm x 10mm x 15mm) venturi generator, doesn't use much air, but generates a lot of vacuum. The other type looks like a fancy solenoid valve, and while using the venturi principle, it generates a *lot* of vacuum and has a 'blow' to disengage the parts at drop-off.