Unrolling Components

Bend Correction Table (BCT)#

Builds an unroll compensation strategy from a press-brake correction table. Each row describes one tooling and material combination: a thickness, an inner bend radius, a bend angle, and the length correction to apply. The flat length of a bend is the sum of the adjacent flange lengths plus that correction, which is normally negative because real bends shorten the developed length. Each bend uses the rows measured at its thickness and inner radius, interpolated along the angle. A bend with no rows at its thickness and radius fails to unroll. Wire the output into the Unroller's Compensation Strategy input.

Inputs#

Flange Measure (FM) options:

• 0 = Virtual Sharp
• 1 = DIN 6935

Outputs#

How It Works#

The four lists T, R, A, C are read in parallel: index i defines one row of the table. All four lists must have the same length.

• A bend uses only the rows whose thickness and inner radius match its own within the model tolerance. There is no nearest match: a bend with no matching rows fails.
• Between two angles of those rows, the correction is interpolated. An angle outside them fails.
• Some generated tables repeat the same correction for every angle above a cap (often 135°). Those rows hold no real data, so a bend above the cap fails instead of using them. Such folds are usually hems.
• Flattened hems do not use the table. They get the hem allowance (see Hem Allowance).

Tips#

• Sample your table densely around the angles you actually bend; sparse tables interpolate but cannot extrapolate.
• Use this when your shop already has a calibrated correction table. It is usually more accurate than a guessed K-factor.

Bend Info (UBI)#

Reads per-bend manufacturing information out of an Unroll Result for documentation and press-brake setup. For each bend it reports the angle, fold direction (up/down), bend allowance, inner radius, the bend's center point on the flat pattern, and a label. Bend centers are handy for placing dimension text or arrows in a drawing.

Inputs#

Outputs#

Tips#

• Use it to write bend specifications for press-brake operators.
• All text outputs start with the bend label, for example B-A: 90. Split on : to get the value.
• For a flattened hem, Bend Allowance is the hem allowance, not a value from the K-factor.

Hem Allowance (HA)#

Sets how much a hem adds to the flat pattern. A hem is pressed flat, so it has no real bend radius and cannot be developed like an ordinary bend. It gets a fixed allowance instead, and presses differ on that value. Only flattened hems use it (inner radius up to half the thickness). Teardrop and rolled hems keep a real radius and unroll like ordinary bends. Use this if your hems come out consistently long or short. Wire a compensation strategy in and the result into the Unroller. Ordinary bends are unchanged.

Inputs#

Outputs#

K-Factor Table (By Angle + Direction) (DSKF)#

Maps each bend angle and direction pair to a K-factor, for materials that behave differently folding up versus down. Supply parallel lists of angles (in degrees), K-factors, and directions. There is no interpolation: a bend angle must match a row, or the Fallback is used. Wire the output into the Unroller's Compensation Strategy input. Use K-Factor Table (By Angle) if direction doesn't matter.

Inputs#

Outputs#

When to Use#

Use when the material bends differently up than down, for example because of grain or rolling direction.

How It Works#

Each bend is looked up by its angle and its direction (Up or Down, as Sheet Info reports it):

• A row with a matching angle (within the angle tolerance) and the same direction gives the K-factor.
• An angle between rows of that direction uses the Fallback. With no Fallback, or with Strict Mode on, it fails.
• An angle outside the rows of that direction always fails.

Tips#

• Needs test data for both directions at every angle you bend.
• Turn on Strict Mode to make sure every bend has its own row.

Example#

Angles:     [90,   90,   120,  120]
K-Factors:  [0.42, 0.38, 0.45, 0.41]
Directions: [up,   down, up,   down]

K-Factor Table (By Angle) (KFT)#

Maps bend angle to K-factor using a lookup table, for materials whose neutral axis shifts with the angle. Supply parallel lists of angles (in degrees) and K-factors, optionally interpolating between entries. Wire the output into the Unroller's Compensation Strategy input. Use K-Factor Table (By Angle + Direction) if the material behaves differently folding up versus down.

Inputs#

Outputs#

How It Works#

For each bend, the Unroller looks up the bend angle in the table:

• An angle that matches a row (within the angle tolerance) uses that row's K-factor.
• An angle between two rows is interpolated when Allow Interpolation is on. Otherwise it uses the Fallback, or fails if no Fallback is given.
• An angle below the smallest or above the largest row always fails. Add rows that cover every angle you bend.

Tips#

• Get angle/K-factor pairs from material testing or manufacturer data.
• Interpolation gives smooth values between rows, but they are estimates, not measurements.
• An angle may appear only once. A repeated angle is an error.

Example#

Angles:    [30,   60,   90,   120,  150]
K-Factors: [0.35, 0.38, 0.42, 0.45, 0.48]

Reroll (Reroll)#

Maps flat-layout points and curves back onto the 3D sheet, and cuts closed flat curves through the sheet solid. Inverse of the Unroll Mapper.

Inputs#

Outputs#

Unroll Mapper (UMap)#

Maps 3D points and curves from the sheet onto the flat layout, matching each one to the face it sits on. Also exposes the rigid transform and source plane for every flange, so you can map or compose further geometry yourself. Points and curves must lie on the side of the sheet that was unrolled.

Inputs#

Outputs#

Unroller (U)#

Unfolds a sheet into its flat pattern. Bend lengths are compensated so the flat folds back to the correct dimensions, using either a static K-factor or a compensation strategy (K-factor table, bend correction table, or hem allowance). Also returns bend axis lines and bend region outlines for drawings.

Inputs#

Orient (O) options:

• 0 = None
• 1 = Bend Axes
• 2 = Min Bounding Box
• 3 = Longest Edge
• 4 = Reference

Outputs#

K-Factor Explained#

When metal bends, the outside stretches and the inside is squeezed. One layer in between keeps its length: the neutral axis. The K-factor gives its position as a fraction of the thickness, measured from the inside surface:

• 0 = neutral axis on the inside surface
• 0.5 = neutral axis at mid-thickness

In real bending the neutral axis moves toward the inside, so K is almost always between about 0.3 and 0.5. Tight bends (small inner radius compared to thickness) sit at the low end, large radii come close to 0.5. The input accepts 0 to 1, but values above 0.5 do not occur in ordinary bending.

Without a Compensation Strategy every bend uses K = 0.45 and the component shows a remark. For parts you will cut, use your shop's K-factor or bend table.

Flattened (closed) hems do not use the K-factor. They get a fixed hem allowance instead: see Hem Allowance.

Placing the flat with Orient#

By default the flat pattern keeps the frame it inherits from the 3D part. If you unroll ten copies of the same profile that sit at ten different angles in the model, you get ten flats at ten different angles. The Orient input removes that: it works out the pose from the flat pattern itself, so parts of the same shape always come out the same way round.

Every automatic mode also puts the bounding box corner of the flat on 0,0,0. Bend Axes falls back to Min Bounding Box on a flat with no bends.

Bend Axes is usually the right default for production work. It keys off the folds rather than the silhouette, so a variant with an extra cutout still lands the same way as the plain part. Min Bounding Box would rotate that variant differently, because its outline changed.

Parts that are symmetric are left as the mode found them: for a symmetric outline both poses are the same picture, so there is nothing to choose between them.

Orient and the alignment planes do not stack. If you pick an automatic mode and also wire Reference 3D or Target Frame, the planes are ignored and the component says so. Set Orient to Reference to use the planes. They also apply when Orient is None.

Tips#

• Set Orient to Bend Axes before nesting a batch of similar parts. It will not pack them tighter on its own (the Nest component already rotates each part), but it makes the flats easy to compare, group, and drive transforms from.
• Wire a K-Factor Table or Bend Correction Table into Compensation Strategy when the K-factor changes with the bend angle.
• The Bend Axes / Bend Regions outputs are useful for creating technical drawings.