What are the measures to control the bending crack of bending metal stamping parts?

In the bending process of metal stamping parts, the smaller the bending radius is, the greater the tensile stress on the outer layer of the bending parts is. When the bending radius is small to a certain extent, it is easy to crack on the outside of the bending part and form waste products, which is called "bending crack". Under the condition of no damage to the sheet metal, the minimum radius of fillet which can be bent into the inner surface of the part is Rmin, and Rmin / T reflects the ultimate bending deformation of the material. In design and practical production, the minimum relative bending radius (Rmin / T) is often used to determine the bending process.

Let's take a look at the measures to control the bending crack of metal stamping parts.

1. Use materials with good surface quality and no defects. If the blank is defective, it should be cleaned before bending, otherwise it will crack at the defective place during bending.

2. For brittle materials, thick materials and cold work hardening materials, the method of heating bending can be used, or the method of annealing first to increase the material shape and then bending can be used.

3. For the bending of thicker materials, if the structure allows, the groove can be cut inside the bending fillet first, and then the bending can be carried out.

4. The bending radius of workpiece is less than the minimum bending radius.

5. The bending curve is perpendicular to the fiber direction of the material.

6. The burred side of the blank is used as the inner side of the bend. Due to the influence of various complex factors, the minimum bending radius is generally determined by test method.