How to calculate the unfolded dimension of sheet metal bending?

The calculation method is divided into two cases, and the specific analysis is as follows:

1. When the relative wall thickness of R angle is very small

It is calculated according to the bending deduction.

For example, 1.75mm is deducted from 1mm thickness sheet (generally determined by the specific experience of each company), 3.5mm is deducted from 2mm thickness sheet, etc.

2. When the R angle is large
Take the median line (i.e. the center line of the inner and outer lines) as the expansion dimension.