In the field of sheet metal processing, flanging is a common forming process, widely used in automotive manufacturing, aerospace, electronic equipment enclosures, and other fields. Flanging technology can not only enhance the strength of the parts but also improve the appearance and increase the convenience of assembly. However, to achieve high-quality flanging effects, reasonable calculation of flanging dimensions is the key. This article will introduce in detail the basic principles and methods of dimension calculation in the sheet metal flanging process.



I. Basic Concept of Flanging



Flanging refers to the bending, stretching, and other forming operations of the edge of sheet metal parts through molds or stamping equipment to form edges with certain height and angle. Common flanging forms include straight edge flanging, arc flanging, and hole flanging, etc.



The main parameters of flanging include:

- Material Thickness (t)

- Flanging Height (h)

- Flanging Angle (θ)

- Bending Radius (r)

- Neutral Layer Coefficient (K)



II. The Calculation Principle of Flanging Unfolding Dimensions



The flanging process is essentially a process of plastic deformation of the material. When calculating the flanging unfolding dimensions, it is necessary to consider the material's elongation characteristics during the deformation process, especially the offset of the neutral layer. The neutral layer refers to the fiber layer whose length remains unchanged during the bending process, and its position is determined by the neutral layer displacement coefficient K, which is usually taken in the range of 0.3~0.5, depending on the ratio of the bending radius to the material thickness.



The calculation formula for the flanging unfolding length L is as follows:



L = π × (r + K × t) × θ / 180



Among which:

- r: Bending inner radius;

- t: Material thickness;

- K: Neutral layer coefficient;

- θ: Flanging angle (in degrees).



For right-angle flanging (θ=90°), the unfolding length is simplified to:



L = π / 2 × (r + K × t)



Three, Calculation of flanging height



When the unfolding length L and bending radius r are known, the flanging height h can be deduced. In the case of right-angle flanging, the relationship between the flanging height and the unfolding length can be approximately expressed as:



h = L - r



Therefore, when designing flanging, the flanging height and bending radius should be reasonably set according to the actual requirements of the part, and the unfolding length should be deduced accordingly to ensure that the size of the part after flanging meets the design requirements.



Four, Consideration of material springback



In the actual processing process, after plastic deformation, materials will undergo a certain degree of elastic recovery, known as 'springback'. Springback will cause the flanging angle to become smaller and the bending radius to become larger. In order to compensate for the error caused by springback, it is usually necessary to make angle compensation in mold design, known as 'overbending'. For example, if the target flanging angle is 90°, the actual stamping angle may need to be designed as 88°~89°.



Five, Matters needing attention in practical application



1. Material property influence: Different materials (such as cold-rolled steel, stainless steel, aluminum, etc.) have different yield strength and elongation, which will affect the forming performance and dimensional accuracy of flanging. When calculating, the neutral layer coefficient K should be adjusted according to the material properties.

2. Mold clearance and pressure control: Appropriate mold clearance and stamping pressure are helpful to improve the quality of flanging and reduce springback.

3. Process verification and trial production: Although theoretical calculations can provide reference values, trial molding and sample verification should be carried out before actual processing, and fine adjustments should be made according to the sample size.



Six, Conclusion



Accurately calculating the dimensions of the flanging is a key link to ensure the quality of part forming and assembly accuracy. By understanding the deformation mechanism of flanging, combining material properties and mold design, reasonably applying the unfolding length calculation formula and considering factors such as springback, the accuracy and efficiency of flanging processing can be effectively improved. With the development of modern CAD/CAM software, many flanging calculations can now be automatically completed with the help of software, but technical personnel still need to have a solid understanding of process knowledge to ensure the rationality and practicality of process design.