Need a shop to produce some plate parts. Dimensions: 0.600+0.015/-0.005" wide x 2.000+0.025/-0.005" long x ~0.060" thick. Hole: One (1) Ø0.200±0.01" thru, 0.040" dp x 62°CSK hole, centered on the part Material: mild steel Surface treatment: Parts must be zinc plated Quantity per order: 5000 Required leadtime from issue of P.O. to Delivery to our dock: 3 weeks. Shops that would be interested in a consignment situation via yearly blanket P.O. are especially encouraged.
If interested, please email me with contact information. Drawing available upon request via email (.pdf)
Sorry about that empty post.. St. Patrick's day an all....
Not that I've ever done any cold forging, but I'll bet a simple progressive die could do this. Pierce the hole, countersink, shave hole, cutoff. Material would hit a stop just before being cutoff - no need for pilots.
The real issue would probably be keeping the forged material from moving the wrong way. Due to the angle of the counter-sink, it would probably go to the top of the hole. Perhaps a camed shaving punch, or in-die broach. Or perhaps it wouldn't even matter. Not very much material there anyway.
"Robin S." wrote in news:7sH_d.73604$ snipped-for-privacy@news20.bellglobal.com:
In this application, I am not sure that 0.01" raised material on the non- countersinked side would make any difference in the functionality of the part whatsoever. This part is a molded-in insert for an injection molding mold. I.E. it gets molded into the part, with the countersink hole side flush with the molded part. (That face is explosed on the finished part.) The countersink hole is filled with plastic during this process, and is what helps retain the plate in place after molding. I am not sure (haven't the foggiest idea, really) that any underside protrusions, within reason, would have an effect on the mold in any way.
No. I haven't learned any forging calculations.. Probably just need a
*bigger* press........
True, but it would be nice not to have to restrict the material, if the application can handle it.
I've never heard of anything like that (doesn't mean anything) but you're moving away from "cheap and practical" and going towards "expensive and difficult to keep running".
I think the material would be on the countersunk side, unfortunately.
An underside protrustion would probably be the easiest problem to solve. The inside of the hole can be shaved after forging. The top of the part could be retained using a stripper, but this will probably increase the size of the press required to make the part, and the stress on the forging punch, stripper and die steel.
That I don't know anything about. 5000pcs total would be unacceptable if there are any hiccups while building the die, I would think...
I'm just thinking that the metal will be driven out, based on the 62º (inc) angle of the countersink. Do you mean to relieve the pointy end of the punch in order to allow a place for the metal to go?
As I said, I'm pretty much talking through my hat, but I doubt the material would go this way if it was allowed to flow up the punch instead. I'm assuming the force on the part produced by the punch would be perpendicular to the surface of the punch. This favours the material flowing up the punch, creating a bulge around the mouth of the hole (countersunk side).
It sounds like if you hit it hard enough, it'll just work. This is mild steel so I doubt spring back would be a significant issue. I'm almost inclined to make a punch of similar dimensions and see what happens with a hammer or arbor press. I've got too much work to do at work. If the garage would just warm up....
Perhaps it wouldn't exactly conform to the punch, but the application may not require such precision. I believe this would normally be done in two operations. One to get the general form, and then a restrike to set the correct form.
It would be nice if the buldge at the mouth of the countersink didn't matter too much.
Volume of a the frustum of a cone: 0.261h(D^2+Dd+d^2) = 0.2618(0.04)(0.2481^2+(0.2481)(0.2)+0.2^2) = .00158in^3
Volume of a cylinder (hole): (pi)r^2h = (pi)(.1^2)(.04) = .00126in^3
Volume of displaced material: volume of cone- volume of cylinder = .00158 - .00126 =.00032
Radius of created half torus: sqrt(((V)(2))/(19.739R)) = sqrt(((.00032)(2))/(19.739)(.1241)) = .002in (looks a bit small....)
That last formual isn't quite right as R is the size of the radius of the middle of the torus, not the ID. Perhaps someone can suggest an alternative formual? Also, I doubled the volume because only half the torus (won't even create an actual torus) will be created...
Anyway, it looks like the bubble would be pretty small. Perhaps it could be smashed down flush in another station. Not sure if it would deform the countersink beyond use though...
I'm not sure if 10-20K pieces would be enough to justify the die or not. A die like this one could probably be made in less than two weeks by one die maker. Perhaps someone else can do the math? I dont' know what it would cost to machine the parts...
True. Putting a pressure pad around the punch would probably contain it. (double acting press would be nice for this, but stripper springs/nitro springs could be used I'm sure).
I don't know how to calculate cold forging forces, not even to get a rough idea. I'll take a look through "The Die Design Handbook" unless you can come up with something.
Does it have to do exclusively with the amount of displaced material?
I think it would be easy enough to shave the hole after forging to set the correct ID.
Yup. Esspecially if excess material can be tolerated on the non-countersunk side. The material may just mush into the break zone within the hole anyway, which would actually result in a nicer hole (or a broken punch trying...)
I was referring to build time as opposed to running time. I'm sure part cycle time in a press would be less than a second.
Obviously one would need to know the part cycle time and consumable tooling costs incurred during machining to see if the die build can be justified.
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