1. Analysis of Bending Die Structure
1. The most common structure of sheet metal bending dies is shown in Figure 1. In this type of die structure, during bending, there is relative sliding friction between the product and the bending block, resulting in abrasions on the outer side of the product (the smaller the R value, the more severe the abrasions). To address this issue, the bending block's R section can be improved by changing it to a roller structure.
2. During bending, the roller rotates under the driving force of the product, causing rolling friction between the outer side of the product and the roller. This significantly reduces visible abrasions after forming, although it cannot be completely avoided.
2. Structural Design of Abrasion-Free Bending Dies
1. Bending punch
2. Flipping bending block (plate)
3. Flipping block positioning
4. Lower floating stripping plate
5. Flipping plate support block
6. Flipping plate support block
7. Lower fixed plate
3. Analysis and Design Points of the Bending Process of the Flipping Plate:
1. At the initial stage of bending, the flipping bending block is horizontally positioned between the lower stripping plate and the flipping plate positioning block, with the stripping plate 1-2mm higher than the flipping bending block. As shown in Figure 4, during the design, ensure that b = a + 0.05 to allow the flipping block to stand up. Also, the lower left part of the flipping plate should be designed with a large R angle, while the turning radius should be c = d - 0.1 to prevent interference between the flipping plate and the positioning block when the flipping plate rotates around the axis.
2. At the beginning of bending, the lower stripping plate moves downward, driving the flipping plate to rotate around the corner of the support block, where the flipping plate will have relative sliding. At this point, ensure that there is an R on the outer side of the flipping plate to prevent interference from the lower positioning block and ensure that it can flip up. Do not chamfer at the corner of the support block, otherwise, the flipping plate may slide out.
3. When the flipping plate rotates to a vertical position between the lower stripping plate and the support block, with the stripping plate continuing to move downward, the flipping plate moves downward under the static friction force of the material, sliding against the support block. When the flipping plate reaches 6-8mm below the support block, the forming is complete. The key in this process is to ensure the stability of the gap between the stripping plate and the support block, and to grind the outer side of the flipping plate and the inner side of the support block to reduce sliding friction. A travel of 30mm for the lower stripping plate is reliable (due to the large travel, air cushion feeding is generally used).
4. During demolding, the lower stripping plate is lifted, and the flipping plate is pushed out upwards under the action of the counter support block. After completely coming out, the flipping plate rotates outward around the support point of the support block under its own gravity to detach from the material. After flipping over, it self-aligns under the action of the large rounded corner of the side positioning block and returns to its original state.
