Sheet Metal Flat Pattern: Back Gauge Dimensions for Production @

[fred.boltinc]

Hi,

I am using Fusion 360 to generate production drawings for our sheet metal shop, which uses two cnc folding machines to form our products.

 The workflow for the bending machines is as follows:

• Fold outermost bend with opposing edge against back gauge (at rear of machine, hence the name 😉 )

• Fold other bends at same edge by working toward center of sheet, back gauge indexing material forward, toward operator.

• Remove part from machine, rotate 180 degrees to index the previously formed edge against back gauge, and repeat process for bends at new edge.

The problem I am running into is how create dimensions from the outer edge of the fully formed bend to the bend lines for the opposing edge. This information is absolutely necessary  to program the folding machine. 

I can calculate the numbers needed, but that is very time consuming and badly hinders production.

I am considering adding superfluous hole features that align with the folded edge that will abut the back gauge to give myself something to work with.

Is there a better way to accomplish this? If not, it should be added, since the flat pattern, as it stands, is not very useful for forming sheet metal in a production environment.

Thank you,

Fred Burtt

Bolt Technologies, Inc.

[jhackney1972 · Accepted solution]

I outlined my idea in a Screencast which may be a bit long to fully explain the process.  The process ends up with a dimensioned view on your sheet metal fabrication drawing showing the dimensions from the folded face to the remaining bend lines.  Of course all the dimension accuracy depends on your sheet metal settings such as k-factor.  I will attach the model but not the drawing since it cannot easily be exported.  You can use the model to recreate the drawing if desired.

[fred.boltinc]

John,

That's a good solution, thank you!

It's a bit involved, as you pointed out, so I'll reserve it for our more complex designs.

I came up with a method that I think will work well for our simpler parts.  The innermost  solid line of the innermost bend marks the end of the undeformed panel, so by dimensioning the opposing bends from that and adding 2x the inside bend radius (since that's set at 1 mat'l thickness for my model) to the dimension and overwriting it, I get the distance from the outside of the formed part to the bend  to be formed. It isn't a truly accurate representation on the print, but that doesn't matter to the guys on the floor.

I also added a "squared" exponent to each of the bends that are formed in the secondary operation to make it easier for the operator to figure out what order to do the bends.

Thanks again, John.

Fred Burtt