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  1. #1
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    66
    Posts
    3,284

    Default LARGE press frame

    I've been asked to make some sheet metal wheel barrow trays that need curved/rolled bottoms, in leiu of straight sharp folds.
    The reason I've been asked to make them, is that a Kelso barrow only lasts about 3 months, and the tray's worn out, the frames last about 6 months as do the bearings in the wheels.
    To make these, I'm looking at making a press similar to a garage press, but 1200 wide inside, it will have 2 X 20 tonne jacks supplying the downward pressure. Does anyone have a press similar in size, that would be able to give me the material size for the uprights, and cross members both top jack holding and bottom rails that are pressed against. Was thinking something like 150 X 75 Channel forming an I, for the top rail, and the same for the bottom rails, with 100 X 100 X 5mm posts for the uprights, sheet will be 2 mm thick.
    I know that no-one will say that the material will be OK, which is why I'm asking if anyone has an existing purchased unit to basically work from.
    Kryn
    To grow old is mandatory, growing up is optional.

  2. #2
    Join Date
    Feb 2009
    Location
    moonbi nsw Aus
    Age
    64
    Posts
    286

    Default

    Kryn, I made a press, with a single 20 tonne jack, from 150 X 75 channel about 6 mm thick. I used it for the whole frame, posts, cross members and at the top I used 2 channels with a 10 mm gap between to allow the jack to be slid left or right depending on the piece that needs a bearing removed. OK I am only half of the power of yours but I think 150 X 75 would be beefy enough to be able to fold that material.
    Just do it!

    Kind regards Rod

  3. #3
    Join Date
    Aug 2011
    Location
    Melbourne
    Posts
    3,726

    Default

    Hi Kryn,

    I think you should be fine for the uprights, since steel has sufficient tensile strength. The big question will be what is needed for the top and bottom that will enable them to withstand the forces from the 2x20T jacks without deflecting more than you are happy to accept.

    If I was to have a guess, I would say that a 150x75 channel would not be rigid enough for a 1200mm span, even though the load is supplied via two jacks rather than a single so it's not a single point loading but it's also not a continuous loading either. It would also depend on the spacing of your jacks.

    Maybe someone here has access to a stress modelling CAD software and can plug in some values for you?

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  4. #4
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    66
    Posts
    3,284

    Default

    Thanks Simon, thanks for reminding me. I punched in some details into the Beam Deflection Stress Calculator, in the section under Conversions and Calculations, something I submitted and forgot about.

    Anyway by upping it from 150 to 200PFC over a 1400 span with 40,000kilo load and a 20,000 continuos load I get a total deflection of 2.5 mm, deflection will be a lot less because there will be 2 of them 100 mm apart and similar above, so that should be close enough for me.
    Kryn
    To grow old is mandatory, growing up is optional.

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