DXF with Bend Data (Press Brakes)

Press brakes' offline programming (Delem Profile-T, LVD CADMAN-B, AMADA, TRUMPF, Bystronic and others) and sheet-metal CAM programs read a flat blank as a DXF: its outline and holes, and its bend lines, each telling which way it bends, how far and round what radius. File › Export › Export… › DXF Files with Bend Data (Press Brake) writes the page worked on that way. A drawing whose industry is Sheet metal or HVAC offers it among its first formats.

What is written

An AutoCAD R12 DXF (the version every program reads), in millimetres or inches:

In the drawing	Layer (Inventor names)	Plain names
The blank's outline (Cut layer)	`IV_OUTER_PROFILE`	`OUTER`
Holes and cut-outs inside it, and the Drill layer's holes	`IV_INTERIOR_PROFILES`	`INNER`
Bend lines on the Crease layer (bend up)	`IV_BEND`	`BEND_UP`
Bend lines on the Reverse crease layer (bend down)	`IV_BEND_DOWN`	`BEND_DOWN`
The Etch layer's marking	`IV_FEATURE_PROFILES`	`MARKING`
Each bend's note	`BEND_NOTES`	`BEND_NOTES`

The Inventor names are those Autodesk Inventor's flat pattern export gives (Layer Mapping for Export Flat Pattern): many press-brake and punching programs map them without setting up. With the plain names, map the layers in your program once.

Each bend line is a LINE, and carries its bend data two ways:

A note beside its middle, on BEND_NOTES: UP 90%%d R2 #1 (AutoCAD shows %%d as °): the way, the angle, the inside radius and its place in the bending order. Programs that read bend data from text read this.
Extended data (XDATA), application PIQ_BEND, in this order: 1000 the way (UP or DOWN), 1040 the angle (degrees), 1040 the inside radius, 1040 the K-factor, 1040 the thickness, 1070 its place in the bending order, 1040 its bend allowance. Lengths are in the file's units.

Where the bend data comes from

Each straight line on the Crease layer bends up, on the Reverse crease layer down, as the Bend Line and Flat Pattern tools and the library's sheet-metal designs draw them. A Bend Line note above the line (UP 90° R2 BA 4.46) gives its way, angle and inside radius; a line without one is bent to Angle of a bend line without a note (90° to start with). The inside radius, K-factor and thickness are the drawing's R, K and T (a sheet-metal drawing has them), else the thickness, 0.44 and 1 mm.

The bending order is a suggestion, as a press brake is usually worked: the bends nearest the blank's edges first, the shorter flange first, then inwards. The Bend table report lists it with the flanges (see the bend table).

Options

Option	What it does
Layer names	Inventor's or plain names, as above.
Bend notes as text	The notes on `BEND_NOTES`.
Bend data as XDATA	The extended data on each bend line.
Angle of a bend line without a note	What a plain bend line is bent to.
Units	Millimetres or inches (the drawing's are converted).
Arcs as arcs, Curve tolerance	Arcs as bulges, or short lines; how far curves may stray.