The bend radius in sheet metal bending is a value specified in the sheet metal drawing, but it is often difficult to determine its actual size during the manufacturing process. In fact, the bend radius in sheet metal bending is related to the material thickness, bending machine pressure, and the width of the lower die slot. Let's explore the specific relationships today:
Based on practical experience in sheet metal processing, the following guidelines can be followed:
1. For sheet thicknesses up to 6mm, the internal bend radius can be directly taken as the same as the thickness of the sheet during bending.
2. For sheet thicknesses greater than 6mm but less than 12mm, the internal bend radius is generally 1.25 to 1.5 times the sheet thickness. For sheet thicknesses equal to or greater than 12mm, the internal bend radius is generally taken as 2 to 3 times the sheet thickness.
3. When the bend radius is R=0.5, the sheet metal thickness (T) is generally 0.5mm. If a radius size greater or smaller than the sheet thickness is required, specialized tooling is needed for processing.
4. When the sheet metal drawing requires a 90° bend and the bend radius is particularly small, the sheet metal should be grooved first before bending. Specialized upper and lower dies for the bending machine can also be used.
The bend radius in sheet metal bending is related to the width of the lower die slot.
Through extensive experimentation in sheet metal processing, it has been observed that the width of the lower die slot has a certain relationship with the bend radius. For example, when using an 8mm slot width to bend a 1.0mm sheet, the ideal bend radius achieved is R1.
However, if a 20mm slot width is used for bending, the upward movement of the upper die during bending causes stretching of the sheet metal to a certain angle. We know that the surface area of a 20mm-wide slot is larger than that of an 8mm-wide slot. Therefore, when using a 20mm-wide slot for bending, the stretching area increases, resulting in an increased bend radius.
Therefore, when there is a requirement for the bend radius of the sheet metal and without compromising the bending machine tooling, it is advisable to use a narrower slot for bending. Under normal circumstances, it is recommended to follow the ratio of the standard sheet thickness to slot width of 1:8. The minimum ratio should not be less than 1:6, and the bend radius can be slightly smaller, but it should not be smaller than 1:4 of the sheet thickness to slot width ratio. It is recommended to prioritize the method of grooving before bending, provided that the strength allows, to achieve smaller sheet metal bend radii.
The bend radius in sheet metal processing is related to the material thickness and the width of the bending slot. A simple and convenient, albeit rough, method is as follows:
For sheet thicknesses up to 6mm, the internal bend radius during bending can be directly taken as the same as the thickness of the sheet. For sheet thicknesses greater than 6mm but less than 12mm, the internal bend radius is generally 1.25 to 1.5 times the sheet thickness. For sheet thicknesses equal to or greater than 12mm, the internal bend radius is generally taken as 2 to 3 times the sheet thickness.
