What software can generate this ?

Discussion in 'Software' started by phmadeira, Aug 25, 2014.

  1. phmadeira
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    phmadeira Junior Member

    What software can generate the cutting file to make this
    see picture
     

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  2. DavidJ
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    DavidJ Senior Member

    I'm not sure if I am understanding the question correctly. Every suite of modern CAD software that I am familiar with can produce cutfiles. Autocad, Rhino, Catia, Solidworks, Pro-E, Shipcontructor, etc. The CNC machines themselves have their own software for translating the CAD output into machine code.
     
  3. SukiSolo
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    SukiSolo Senior Member

    Agree with DavidJ, almost any half decent 3D modeling software can output an IGES or STEP file capable of being read by a CNC package. The CAM package generates the G code output which drives the cutter/router/laser cutter/water jet cutter/mill etc. The advantage of the CAM software is it can generate tool paths which can be optimised for different output machines.

    A lot of the frames only require a 2 1/2 axis machine to fabricate. Some complex curved pieces may require a 3 or 4 axis machine. The work can be subdivided at that level. Not forgetting that the initial file may also be used for other processes like lost wax casting, 3 D printing etc.
     
  4. phmadeira
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    phmadeira Junior Member

    Ok, thank you for your answers
     
  5. TANSL
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    TANSL Senior Member

    Only high price programs can automatically generate these figures and files for CNC cutting. The more modest programs are based on the drawing of each piece, drawn by the user. In addition the user, manually or aided by the software, must create the "nesting" of various pieces on a plate. Once obtained, in one dwg, dxf file or the like, most of the cutting machines are able to interpret and translate it into machine language. There are also in the market processors that createthat the file in machine language from a dwg file.
     
  6. JosephT
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    JosephT Senior Member

    It appears the flange is welded. Is that correct (versus solid machined station frame)? If it is indeed welded you have a 3 part manufacturing process:

    1. Cut flat plate
    2. Cold roll the flange
    3. Weld flange to flat plate

    There are quite a CAM tools that can be used to cut the plate, cold roll the flange & even generate the code for the weld (e.g. robotic weld). Most likely though a lower cost solution for fewer units would be to just have a good welder do the last step of mating the flange to the plate.

    Good looking frames on that CAT.
     
  7. alidesigner
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    alidesigner Senior Member

    Anyone else concerned that the cutouts are more than 50% of the web area?
     
  8. TANSL
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    TANSL Senior Member

    You are right but there are methods of compensation of cutouts (although they are expensive).
     
  9. baeckmo
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    baeckmo Hydrodynamics

    Certainly, and on top of that it seems they are using T-profiles for longitudinals, welded to the flange of the T. This means that both the long and frame material is heat affected in the zone with the highest bending and shearing stress.

    As TANSL notes, there are ways around, but from what is seen in the pic at this stage of building, there is no sign of additional measures.

    Would be interesting to see a few comments from Ad Hoc on this, hope he chimes in!
     
  10. TANSL
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    TANSL Senior Member

    Attached is an extract of the rules of BV in relation to the cut-outs on web frames.
    Do not think any CS accept the cut-outs seen in the figures, without some form of compensation.
    It will also be in teresting to see how the passage of the longitudinal members, primary structural elements, via transverse bulkheads will be solved.
     

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  11. MikeJohns
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    MikeJohns Senior Member


    It's not uncommon to see up to half the web cuttout to accommodate the primary framing when T sections are used. The skin acts effectively as a very large flange so there may be little stress from primary loads on that side of the web anyway . But it all needs careful design consideration.

    Providing the framing is properly designed for the weld fatigue strength there's no problem welding the primary framing T flange to the frame, it also stiffens the secondary frame web wrt buckling. But bracketed intersections ( of the long and the transverse) may be necessary unless the member is over designed anyway.
     
    Last edited: Sep 6, 2014
  12. TANSL
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    TANSL Senior Member

    I think there is some confusion in defining what elements are primary and secondary.
    Moreover, the cutouts reduce the surface that resists the shear forces experienced by the webframes which solves only putting additional material which support such efforts. No solved by welding secondary element to the primary.
     
  13. MikeJohns
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    MikeJohns Senior Member


    Yes maybe it depends what you learned and what ISO now adopts. I've always called the primary plate stiffeners the primary frames and they are the frames that define the framing method ie longitudinally or transversely framed.
    A small boat usually has only primary framing, as boats get larger secondary frames are required to reduce the span of the stiffeners, and then larger still tertiary frames support the secondary frames which support the primary stiffeners. That seems the most sensible way of defining framing and it's commonly used in naval architecture.

    Shear strength of steel and alloy framing is not really an issue. The principal stresses are bending and the principal failure mode is buckling. To fulfill those criteria you'll find shear is relatively negligable. But fatigue is always the bugbear of alloy structures.
     
    Last edited: Sep 6, 2014
  14. TANSL
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    TANSL Senior Member

    In my opinion a secondary element does not support a primary element, is just the opposite.
    I donĀ“t know what is a terciary element. I had never heard.
    Perhaps due to my poor understanding of English, I had always thought that the "frames" were cross-sectional, never longitudinals.
    This is not right:
    Any beam subject to bending undergoes some shear stresses that may be important. If the cross section of the beam is not enough, the beam will collapse.
    The shear forces should be studied. Only be negligible if the beam has the appropriate section. Therefore, the cut outs can be a major problem if the cut material is not compensated.
    Many elements of the structure does not suffer from buckling and therefore, except in certain structures, buckling is not a problem.
    I'm not talking about ISO or any other regulation. I'm talking about the basic knowledge to understand how to conceive the structure of a ship.
     

  15. MikeJohns
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    MikeJohns Senior Member

    I'm not saying that shear stress is non existant. Direct effective shear stress in theat transverse from the panel distributed load is going to be what ? ............ lets say worst case around a 1/5 the bending stress.
    Long before you can get a shear failure of that frame the grillage will fail in buckling. The higher stressed additive ( shear plus bending stress) parts of the structure will be the skin and the flange which is factored into the scantling anyway. Much of the web is effectively structurally redundant.

    If you are interested in this maybe a new thread and I can post some FEA grillage analysis for you when time allows. Note I'm not saying this is a great construction method, I'm commenting on the shear vs bending stress magnitudes when you look at the actual stresses designed for.
     
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