When using free bending, the bending radius is 0.156 times the opening distance of the die. In the free bending process, the opening distance of the die should be 8 times the thickness of the metal material. If the bending radius is almost as small as the material Thickness requires bottomed die forming. However, the pressure required for bottomed die forming is about 4 times larger than free bending.
If the bending radius of the CNC Press Brake machine is smaller than the thickness of the material, a punch with a front-end fillet radius smaller than the thickness of the material must be used, and the imprint bending method must be used. In this way, 10 times the pressure of free bending is required.
The punch and die are processed at 85° or less than 85°. When using this group of molds, pay attention to the gap between the punch and the die at the bottom of the stroke, and it is sufficient to compensate for the springback and keep the material at about 90° The excessive bending.
Generally, the springback angle of the free bending die on the new CNC Press Brake bending machine is ≤2°, and the bending radius is equal to 0.156 times the opening distance of the die.
The die angle is generally 86 ~ 90°. At the bottom of the stroke, there should be a gap between the male and female dies slightly larger than the material thickness. The forming angle is improved because of the tonnage of the bottomed die Larger (about 4 times of free bending), which reduces the stress that usually causes springback in the bending radius.
The imprint bending is the same as the bending of the bottom die, except that the front end of the punch is processed to the required bending radius, and the gap between the punch and the die at the bottom of the stroke is less than the thickness of the material. Due to the application of sufficient pressure (about 10 times that of free bending) ) Forcing the front end of the punch to contact the material, basically avoiding springback.
In order to choose a low tonnage specification, it is better to plan for a bending radius larger than the thickness of the material, and use the free bending method as much as possible. When the bending radius is large, the quality of the part and its future use are often not affected.