Wizoscript & Sheet Metal

[XVdTfgW5vM]

Started with the 1st example at http://www.wizotools.com/tag/parameters/ and a simple 1x2x3 block. Wanting to run the script against a sheet metal part, released that the file extension AD_SMP added to the filename throws an error. It seams the extension AD_PRT is hard coded. Not expecting it to work, changed the file extension on the sheet metal part from AD_SMP to AD_PRT. Both Wizoscript and Alibre seam to be happy with this.

Any comments or insight?

Alibre Design™ Expert
Alibre Design Version:[ 2017 ] 64-bit
Microsoft .Net Framework 4.0.30319.42000
WizoScript 3.51 build 745
Windows 10 64-bit

Bob

 

[ajayre]

Hmmm... well, not really understanding sheet metal it's not something I have looked at. I will look into it as soon as I have time.

Interesting user name - looks like a password.

Andy

 

[Lew_Merrick]

Andy -- Be aware that the basis of "punch and bend" sheetmetal are a series of "shortcuts" from WWII intended to make is easier to allow untrained farm kids to design and manufacture sheetmetak parts for Lockheed and Ford. The "system" was designed to get such people "within a 1/16 of an inch." It eas known (back in the day) as the "Lockheed K Factor" approach. [And we still call it the "K-Factor."] You can get much closer to a real "fit" if you merely allow for the "neutral bend length" in your bends. [The"neutral bend radius" for a piece of sheetmetal is the thickness divided by natural Log of the quantity (inside bend Radius + thickness) divided by the inside bend radius. [I have designed 60 "bend" parts that have ended up within .005 inch of designed form using the "neutral bend radius" approach..]

If you fit an appropriately spanning "elliptical arc" from the "midpoimt" of the "bend start" to the "midpoimt" of the"bend end," you can design sheetmetal parts that fit within a couple ten-thousanths of an inch. [Few things are worth that much hassle!]

 

[Markaj]

Andy -- Be aware that the basis of "punch and bend" sheetmetal are a series of "shortcuts" from WWII intended to make is easier to allow untrained farm kids to design and manufacture sheetmetak parts for Lockheed and Ford. ]

Interesting - I spend my day wrestling with sheetmetal work (Inventor), & am not entirely convinced of it's merit!
It used to be so much easier in the days of drawing boards & the bend allowance from the Zeus Book.
The trouble is is that there is no facility in the software to allow for the fact that metal 'gives a bit', so you spend your time trying to come up with dodges to make things work.

 

[Lew_Merrick]

Markai -- OK, assuming you are forming your sheetmetal in a "closing press" (as opposed to a "folding press"), then the issue is one of calculation of the deformation due to the Hetzian contact stress from the pinch at press closing. It is possible (but a real PITA) to make such calculations.

 

[Markaj]

Markai -- OK, assuming you are forming your sheetmetal in a "closing press" (as opposed to a "folding press"), then the issue is one of calculation of the deformation due to the Hetzian contact stress from the pinch at press closing. It is possible (but a real PITA) to make such calculations.

Yep - the trouble is is that there is no allowance in 3d software for a tap with the gentle persuader.
It a bit like trying to get the fillets on patterns for castings to work (say reproducing old wooden patterns) - when in real life the fillet just squidged in.

 

[Lew_Merrick]

The problem with allowing the tap of a gentle persuader is that you have to allow deformation through the tangent or secant modulus to be evaluated.

 

[JST]

I detest the fact that ALL the sheetmetal programs seem to use those k-factors instead of the bend allowance/neutral axis approach, which is what I have used for 30+ years. We worked out bends to about 15 thou in location for 18 ga sheet.

The two approaches are related to each other, but only the k-factor is accepted in the programs.

 

[HaroldL]

The two approaches are related to each other, but only the k-factor is accepted in the programs.

That may be partially true of Alibre, it also allows for using the unfolded length, though I've never used it. SolidWorks allows a choice of inputs for bend data: K-factor, Bend Allowance and Bend Deduction. Something I wish Alibre would allow as well as having a drop down list of materials, etc. that you could select from.

 

[JST]

When I used SWX, I never did find a way to use the bend allowance...... by which I really mean not a distance, but a bend line location in the material.

 

[otrotabi]

Hi, the original question went to other issues, but: Is it possible to draw a sheet metal part using wizoscript/alibre script ? Bends, flat patterns ? Or, if it is not possible so far, is it possible to script-draw a sheet metal part as a regular part and afterwards use the "convert to sheet metal" tool to get the flat pattern ? Thanks.