Unrolling Components

Bend Correction Table (BCT)

Builds an unroll compensation strategy from a press-brake correction table. Each row of the table describes one tooling/material combination: a thickness, an inner bend radius, a bend angle, and the length correction z to apply for that combination. The flat-pattern length for a bend is computed as the sum of the adjacent flange lengths plus z (z is typically negative, since real bends shorten the developed length). When the unroller asks for a bend, this component finds the table row whose thickness and inner radius are closest to the part's, then interpolates the correction value linearly along the angle. Source these tables from your press-brake controller, your material supplier, or measurements from test bends.

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Outputs

Tips

• 0.5 is a safe neutral fallback K-factor for most steels.
• Sample your table densely around the angles you actually bend; sparse tables interpolate but cannot extrapolate.
• Use this when your shop floor already has a calibrated correction table — usually more accurate than guessing a K-factor.

Direction-Sensitive K-Factor (DSKF)

Creates a K-factor strategy that varies based on both bend angle and direction. This enables more accurate unrolling when material behavior differs between upward and downward bends. Each angle-direction pair maps to a specific K-factor value representing the neutral axis position.

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Outputs

When to Use

Use when the material shows different bending behavior for upward vs. downward bends
(grain direction, rolling direction, etc.).

Tips

• More accurate, but requires more test data.
• Strict mode ensures all bend combinations are explicitly defined.
• Good for high-precision applications.

Example

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

K Factor Table (KFT)

This component, K Factor Table (KFT), allows users to define a mapping between bend angles and K-factors for sheet unrolling. It accepts a list of angles (in degrees) and corresponding K-factors, along with a fallback K-factor to use when no match is found. The component can optionally interpolate between angle values for more precise compensation. Duplicate angles are handled by using the last provided K-factor for each angle, with a warning issued for duplicates. The output is a compensation strategy that can be used in unrolling operations to calculate accurate bend allowances based on the provided data.

Inputs

Outputs

How It Works

• Maps specific bend angles to K-factor values.
• Looks up the K-factor based on the actual bend angle during unrolling.
• Uses the fallback value if the angle is not in the table.

Tips

• Get angle/K-factor pairs from material testing or manufacturer data.
• Interpolation creates smooth transitions but may not match real behavior.
• Duplicate angles use the last provided K-factor (a warning is issued).

Example

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

Unrolled 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, local radius, the bend's center point on the part, and a label. Bend centers are handy for placing dimension text or arrows in a drawing.

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Outputs

Tips

• Use to generate bend specifications for press brake operators.
• Bend centers are useful for positioning annotation text/arrows.
• Labels follow the convention: "B" for regular bends, "HB" for hem bends.
• Export to a spreadsheet for manufacturing documentation.

Unroller (U)

Unfolds a sheet into its flat pattern. It walks the sheet's bends in order, rotates each flange flat, and compensates the bend length so the flat pattern folds back to the correct dimensions. Bend length is compensated either by a static K-factor or by a compensation strategy (K-factor table, bend deduction, or a press-brake correction table). Besides the flat BREP it returns the bend axis lines and bend region surfaces (useful for drawings) and a detailed Unroll Result for the Unrolled Bend Info component.

Inputs

Outputs

K-Factor Explained

K-factor represents where the neutral axis is during bending:

• 0.0 = Neutral axis at inside radius (material stretches more)
• 0.5 = Neutral axis at centerline (symmetric)
• 1.0 = Neutral axis at outside radius (material compresses more)

Tips

• Start with K=0.5 for initial tests.
• Wire a K Factor Table into the Compensation Strategy input for angle-dependent compensation (more accurate).
• The Bend Axes / Bend Regions outputs are useful for creating technical drawings.