4。 For example, in reference [8], the measured rebound rebound test is described, and the table is subjected to unconstrained cylindrical bending. There is no blank holder, so bending dominates deformation. Due to the geometric shape of the die (Figure 5) and complicated contact boundary conditions, the springback after forming is large in the forming process. The springback in this experiment is measured by the angle θ, as shown in Figure 5. The dimensions of aluminum alloy plate (6022) used in the experiment are: I = 120, =30, = 1 mm stamping method: the die and point-to-point trajectory are tracked at a constant speed until the die reaches the aluminum plate leg (Figure 6 above). At the bottom, the rebound angle is shown in Figure 6. When the minimum rebound angle occurs, the punch returns to the limb and tends to be stable. Fig. 7 shows the hydraulic pressure, obtains the measured values of the chamber pressure and the punch speed, and obtains the idea of different positions. This method realizes the calculation of rebound angle. The rebound angle calculated by this method is based on the sum of two angles, which are measured between the limb surface and the vertical plane. This method is based on the following image processing operations: the original image (Figure 8 on the upper left) is converted into a gray image. So, what about the median filter? Adjustment of strength value; Gray image conversion, through the threshold, applies morphological "cleaning" operation to the binary image, and deletes the binary image and subsequent isolated points. The binary image shows the above operation in Figure 8 in the upper right corner. Calculate the rebound angle from an algorithm suitable for selecting a "line" containing both lower limbs in the binary image window (article shown at the bottom left/Figure 8 on the right). The algorithm at home? Horizontal line, intercepting limbs near the white "line" at the bottom and top; Then the middle point is a white "line" with the same index, and it is found to be two horizontal lines. And my value, as shown in figure 9, and then used to calculate the sum? And the vertical plane: θ2 = 180/π×Tan (liter/hour). In order to reduce the calculation error, the same process is repeated around different horizontal lines. Angle calculation, the value of the medium is θ2. Using the left window image, use the same program to calculate θ 1. The rebound angle of the value: 1+2=θθθ. Angle in the example of Figure 8: θ 1 =29.4? ,θ2 =27.7? And θ=57. 1? .