Discussion on the bending coefficient in sheet metal processing
From: Mold Network Time: 2008-5-6 17:26:50 Views: 302 times Editor: abihau
Abstract: In view of the importance of determining the bending coefficient in sheet metal processing, a theoretical calculation is carried out on the unfolded material of an ordinary steel plate (SPCC) and a workpiece with a bending angle of 90°, and the relevant influencing factors of the bending coefficient are analyzed. , based on the test data, a mathematical model was established, and through computer optimization and combination, the basic rules for the calculation of the bending coefficient (the calculation formula of the bending coefficient) were determined.
Keywords: sheet metal; processing; bending coefficient
1 The importance of determining the bending coefficient
In sheet metal processing, the parts are unfolded When calculating, the craftsman determines the bending coefficient (i.e. consumption) based on experience. The bending coefficient determined by the process documents prepared by different craftsmen is also different. After consulting a large number of relevant sheet metal processing manuals, I did not find a clear formula to calculate the bending coefficient. I could only find the bending coefficients of different bending inner arcs, and the inner arcs are related to the processing technology plan and use different methods. The bending die groove is wide and the inner arcs are also different, which makes it impossible to determine the accurate value of the bending coefficient in the process documents. This not only affects the standardization and rationalization of process documents, but also brings difficulties to workshop production and leads to unstable product quality.
With the continuous advancement of science and technology, computer applications are gradually developing towards CIMS systems. The computer's automatic calculation of unfolded materials must first be solved, that is, the automatic determination of the bending coefficient must first be solved before we can talk about the computer-aided preparation process, including the automatic preparation of process documents, the automatic calculation of unfolded materials, the automatic calculation of material consumption quotas, etc.
Some manufacturers in Beijing that are implementing CIMS systems have not solved this problem with their software: As a manufacturer of CNC machine tools, the determination of the bending coefficient is a patented product, which is very important to users of machine tools. It's confidential. Therefore, the calculation method for determining the bending coefficient must be solved by oneself.
2 Theoretical calculation of unfolded material
When sheet metal is bent, compression occurs on the inside and tension occurs on the outside. The compression on the inside gradually decreases from the inside to the outside, and the tension on the outside It also gradually shrinks from the outside to the inside. Near the center of the plate thickness, the compression and tension are close to zero. This surface in the middle of the plate thickness is called the neutral layer. The following is a theoretical calculation of the unfolded material based on the neutral layer.
2. 1 The bending inner arc radius R ≥5t (t is the material thickness)
When the bending inner arc radius is greater than or equal to 5 times the material thickness, There is no thickness change at the bending point of the material, that is, the neutral layer is on the center line of the material thickness after bending, as shown in Figure 1-a.