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Thread: Pierce Load Calculation on a solid billet

  1. #1
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    Pierce Load Calculation on a solid billet

    I am doing a calculation on piercing a billet during seamless pipe extrusion. I searched online for a formula but onyl be able to obtain formula for piercing sheet metal..which is

    Piercing force F = P (perimeter) x T (sheet thickness) x PSI (shear rating of material)

    It doesnt applied to a billet caused billet thickness is about 40 inches. It gives me a humongous force.

    Some basic information of what I am trying to do is...

    There is a 500 ton piercer use for making seamless tube. We want to know if 500 tones will pierce the solid biller or do we need to start by drilling a hole through billet,

    Please refer me to a formula and dimension that I will need.

    Thanks

  2. #2
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    You are kidding 40" thick?

    Billet of what material?

    Diameter of pierced hole?

    Humungous sounds way too little, no matter what you fill in for the above. Not even if it is a 1" diameter hole in 40" of billet Pine lumber.

  3. #3
    Administrator Kelly Bramble's Avatar
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    Yes, what PinkertonD said...

  4. #4
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    Quote Originally Posted by PinkertonD View Post
    You are kidding 40" thick?

    Billet of what material?

    Diameter of pierced hole?

    Humungous sounds way too little, no matter what you fill in for the above. Not even if it is a 1" diameter hole in 40" of billet Pine lumber.
    Billet is BeCU.

  5. #5
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by whlock View Post
    Billet is BeCU.
    Well, the equation to determine the force is given in simplicity here ---> http://www.engineersedge.com/sheet_metal_pierce.htm

    I don't think will work for you however. I think the limitations on piercing for materials over 60 ksi is that the diameter is peirce tool be at least 2x the material thickness.

  6. #6
    Lead Engineer RWOLFEJR's Avatar
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    I have very limited (read next to none) knowledge about piercing mills and manufacturing of seamless tube. But I'm sure the punching formula isn't going to be complete enough for what you need to find out. If anything... in that formula I'd guess that you'd want to plug the number 1 into the part for sheet thickness... Reason being... you're only working on displacing a small portion of the billet at any given time. You aren't working or moving the material at the opposite end of the billet when the piercing point comes in contact with it. You aren't shearing... you're just moving the material. Then you'll need to take into account the losses in strength at whatever elevated temperature you will poke this thing at. The formula would also need to take into account the O.D. of the billet vs. the size hole you're poking into it. The formula would need to consider the amount of material being displaced. Piercing a 2" diameter hole into a 5" diameter bar should be a good bit easier than a 2" diameter hole through a 12" diameter bar. But again... I'm not up on piercing so you'd be best to talk to people in the know on the operation. I'd call the manufacturer of the equipment or dig through any literature you have on it. One thing I'm certain about is the formula doesn't require the entire length of the billet. If anything maybe the length of the taper on your point. The only place the length would come into play is calculating the growth in length vs. the diameter of the piercing point. Your machine is only going to handle a parts so long.

    I'm pretty sure when folks pierce billets they put a center drill in the end first to ensure the point starts out on the right track. Also pretty sure that they are rotating the part pretty quickly as they push the point through the billet and the work piece is hotter than the hinges of hell... Probably using something like Waspalloy for the points and several of them in rotation so they don't let them get too hot. Then again you are in possession of one so you surely know more about how it works than I do.

    So in short. You basically can't use any of the information I just spewed out. Only intelligent thing I said was to contact the manufacturer.

    How about doing me a favor... When you do find out exactly how this would be calculated, how about letting me know. I'm very curious and would be interested in hearing how it's done.

    Good Luck,
    Bob

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