Algorithm for Unfolding at Three Bending Angles
Bending: External bending, unfolded size 100*100, thickness 2.0, material iron sheet
Bending deductions vary for each factory, and the deduction for bending also varies depending on the selected groove.
Below are the bending deductions for grooves six times the plate thickness for reference:
1.0 deduction 1.75
1.2 deduction 1.95
1.5 deduction 2.36
2.0 deduction 3.35
2.5 deduction 4.2
3.0 deduction 5.0
4.0 deduction 6.8
5.0 deduction 7.8
The unfolding in the diagram above is L = 100 + 100 - 3.35 = 196.65
Unfolding involves subtracting the number of bends from the external bending size by the corresponding bending deductions.
The 90-degree angle above has been discussed before. Now, let's talk about unfolding at acute and obtuse bending angles.
Unfolding for obtuse angles: L = sum of external bending sizes - (180° - obtuse angle) / 90 * corresponding plate thickness bending deduction
Unfolding: L = 141 + 100 - (180 - 135) / 90 * 3.35 = 239.325
When bending at sharp angles, the bending points cannot be sharp after normal bending. Therefore, the bending sizes marked in the diagram as 137 and 111 need to be adjusted as they should be larger than the sizes after normal bending.
For the sharp angle's inner R1, set it as 0.2 during unfolding, and the outer R2 is 0.2 plus the plate thickness.
After modification, when marking dimensions, choose the midpoint of the outer R arc.
After marking the dimensions, we need to calculate the unfolding.
Unfolding for acute angles: L = sum of external bending sizes - (acute angle / 90 degrees) * corresponding plate thickness bending deduction
L = 131 + 105 - (30 / 90) * 3.35 = 234.88
Previously, we mentioned discussing how to draw bending lines in unfolding. Due to time constraints today, we will first explain the drawing of bending lines after a simple 90-degree bend.
After unfolding, as calculated earlier, it is 196.65.
The position of the bending line is the distance offset by the first edge of the bend: S = bending size - half of the bending deduction
S = 100 - 2.35 / 2 = 98.825
