During the bending deformation process, the material on the inside of the bending radius is compressed, while the material on the outside is stretched, with the material maintaining its original length forming an arc. This arc represents the material's neutral line in sheet metal mechanics, which is used to calculate the flat length. It cannot exceed half the thickness of the sheet metal's geometric shape.
The coefficient K is a calculation factor for the position of the material's neutral line.
In linear flat pattern development, K determines the coefficient used in calculating the structure of the bending radius section (any features that result in this shape) for the flat length calculation. The range is 0-1; the default value is 0.44. The formula for calculating the flat length of a bend is as follows:
Flat result length = 2*PI*(bend radius + K*thickness)*(bend angle/360)
It is evident that with different K coefficients set, the flat length with bends will vary. Under these conditions, all relevant parts in the model will use the same coefficient for flat pattern calculations. However, in "bend" mode, different calculation coefficients may be used for different parameters to ensure more accurate and precise results.
Depending on the material and specific sheet metal design rules, the K coefficient can be adjusted to an appropriate value to achieve a more accurate length after flat pattern development. The K coefficient is material-dependent and largely influenced by the ratio of sheet thickness to bend radius. For the default settings in Inventor, where bend radius/thickness = 1.0, K = 0.44, this aligns well with common design practices.
Bend radius/thickness:
0.1 0.25 0.5 1.0 2.0 3.0 4.0 >4.0
K: 0.32 0.35 0.38 0.42 0.46 0.47 0.48 0.5
The addition of coefficients to internal and external dimensions is used in empirical formulas for bending. The internal dimension refers to the length of the bend without considering the material thickness, while the external dimension includes the material thickness. The coefficient is a correction factor considered during bending and is purely empirical, typically applied in rough estimations. Regarding determining the bend radius, if you are in a design role, it is up to you to decide, considering assembly relationships, aesthetic considerations, and manufacturing feasibility. Generally, the material thickness is used for the inside of the bend, following basic sheet metal rules.
The coefficient K is a calculation factor for the position of the material's neutral line.
In linear flat pattern development, K determines the coefficient used in calculating the structure of the bending radius section (any features that result in this shape) for the flat length calculation. The range is 0-1; the default value is 0.44. The formula for calculating the flat length of a bend is as follows:
Flat result length = 2*PI*(bend radius + K*thickness)*(bend angle/360)
It is evident that with different K coefficients set, the flat length with bends will vary. Under these conditions, all relevant parts in the model will use the same coefficient for flat pattern calculations. However, in "bend" mode, different calculation coefficients may be used for different parameters to ensure more accurate and precise results.
Depending on the material and specific sheet metal design rules, the K coefficient can be adjusted to an appropriate value to achieve a more accurate length after flat pattern development. The K coefficient is material-dependent and largely influenced by the ratio of sheet thickness to bend radius. For the default settings in Inventor, where bend radius/thickness = 1.0, K = 0.44, this aligns well with common design practices.
Bend radius/thickness:
0.1 0.25 0.5 1.0 2.0 3.0 4.0 >4.0
K: 0.32 0.35 0.38 0.42 0.46 0.47 0.48 0.5
The addition of coefficients to internal and external dimensions is used in empirical formulas for bending. The internal dimension refers to the length of the bend without considering the material thickness, while the external dimension includes the material thickness. The coefficient is a correction factor considered during bending and is purely empirical, typically applied in rough estimations. Regarding determining the bend radius, if you are in a design role, it is up to you to decide, considering assembly relationships, aesthetic considerations, and manufacturing feasibility. Generally, the material thickness is used for the inside of the bend, following basic sheet metal rules.
