general questions on press sizeing

[llilrex]

I am constructing a press that will be used for blanking and cupping and drawing. it will be blanking .125" thick by .5" diameter disks of 1018 steel. and cupping the same disk.

how much force would it take to accomplish said operations? I am hoping to make the press capible of multiple simultanios parts, it would be nice to know an estimated force per part.

on the blanking is it the shear strength of the steel multiplied by the area of the blank edge?

so based of the befor mentioned assumption being that the tensil strength of anealed 1018 is 60,000 psi and .577 of that is shear strength, it would take 3.3 ton to blank the disk. is this a correct analisys?

I am not sure what it would take to calculate the cupping operation though, or the drawing operation. but I once heard that the blanking process uses more force then the other two operations. is this true?

[llilrex]

This project seems quite large for a hobby, but I am determined, I don’t know how elaborate I am going to get but, I was wondering, when drawing 1018 how often does the steel have to be annealed? I was thinking about combining all of the operations in one press stroke
Blanking, cupping and two stages of drawing might be accomplished by having a short stroke cylinder pushing a longer stroke cylinder when the blanking pin cuts the blank it has a pin in the center of it that would be the cupping pin. Then if the pin is allowed to pass the cup further into the die, it could go through more drawing dies before finally being stripped off of the pin and dropped. I was thinking of ganging 5 at a time.

[Geof]

To answer some of your questions:

Your calculation for the force required to shear the material is more or less correct but in practice you would use two or three times the theoretical 3.3 tons.

Your idea of doing things all in one bang would result in long skinny tooling that would likely fail by buckling sideways.

You probably do not need to worry about annealing because 1018 does not work harden much if at all.


Final comment; cupping .5" diameter 1/8" thick in 1018 may be difficult. Do you plan on making your own tooling?

[One of Many]

A picture or drawing of the part should help.

One process for forming and punching a part like this is using a progressive die in a punch press. Typically, the first stage is to start the stock strip with index holes for alignment in latter stages and if possible, knocking out relief or required sections that allow the part to form without distortion or as planned distortion. Only after the part is complete, will it be trimmed from the stock.

The drawing process takes a controlled reduction in material cross section within the blank. As the material thins, it must flow from within the blank and support material holding it stable. Blanking 1/2" disks makes it very tough to hold and allow flow. How much of it is support material?


The next process would be more like coining and takes a whole bunch more tonnage if it can be done in one shot at all.

DC

[llilrex]

I tried to get a drawing put together but have been unsuccessful. I am having problems exporting to jpeg. But anyway I am fooling around with a number of things, one of them is the scales of an armor piece, they are hexagonal and have a slight dish shape, they are used for Japanese brigandine. I have been hand cutting them, and it is taking a really really long time. The other project is in the making of my own steel casings for 9mm parabellum. It is in this project that the deep drawing will occur. So although I would supply the drawing, nearly everyone has seen or can see the 9mm casing that I am talking about. The tooling should be able to produce 5 half done casings per stroke. Another set of tooling will be required to "head" the casing. And it will be similar to coining.


So far my press and tooling is being designed to blank the material, and draw it with a single press stroke. The blanking die is supported by a block while blanking and then removed to allow the die to freely slide up the drawing punch during the drawing process. When I get my CAD to export JPEG I will post it for those interested.

I will be making all of my own dies. out of A2 tool steel. I don't yet have the capibility to shape carbide.

[One of Many]

It may be easier to use the PRINT SCREEN key on your keyboard, just left of SCROLL LOCK.

After you have pressed the PRINT SCREEN key. Go to MSPaint, then click on the EDIT tab and click PASTE. You should see your screen capture pop into the window. If you know how to use it to modify pictures, you can cut just the portion you desire to paste that section into a new MSPaint file, then skew it for size up/down and save it in many different formats of BMP,JPEG etc.

DC

[llilrex]

hey!!! I knew that! I dont know why I didnt think of it this time. ok then, when I get back to my cad computer at home I will do that. thanks

[One of Many]

Now that I understand what the disks are going to be used for. This may take a special alloy and mill processing in order to get it to elongate at that wall thickness. Stock sheetmetal is nowhere near consistant enough to draw like that. The problem is hard and soft spots. The sweet spot is going to be somewhere between the yield and untilmate tensile, which requires a very narrow range of specifications to be productive.

The tooling and equipment investment is far greater in R&D than finding these ammo casings by the ton for basic reloading purposes. Not to mention the secondary automation to coin and machine the head and primer seat within half thou tolerances.

Not to rain on your parade, but it is simply unrealistic economics competition in scale. The legality of producing ammo at those quantities might be another huge hindering factor.

I can just hear the black helicopters hovering now! LOL!

DC

[llilrex]

Well that is why they call it a hobby, if it were to make since, be economical, and efficient, it wouldn’t be a hobby now would it. Besides I think I would like racking my head against these insurmountable problems more then actually shooting the ammunition. It is this brand of insanity that keeps a site like this going anyway.

Helicopters? So that’s what those things were flying in the middle of the night! But seriously the legality is simply that I cannot produce ammunition to sell without the tax license to do so. So that really makes it without economy doesn’t it!

[llilrex]

So you don’t think that I can draw the steel that thin? I was thinking of using hot rolled .125" by 3" stock that has been annealed in a gas furnace and pickled afterward. Do you think that this would suffice in normalizing the material? As far as the alloy goes, I wonder what they used in WWI when they started to make casings out of steel. I read a patent that used 1020 mild steel. I assumed that they could be made out of that alloy, although I am aware that patents don’t actually fallow reality. I don’t know, most of this stuff is new to me, I guess that’s why I am here huh. Thanks for the help by the way, I have said it before, this is my favorite forum. Allot of knowledge and experience here!

so about press sizeing? to punch out 5 per stroke? 30 ton? 50 ton? 100 ton? just as a guess what size of press would you use?