1. Bending is the most important link in sheet metal manufacturing. The quality of the CNC Press Brake Machine will directly affect the production of the next process and the quality of the entire product. The rationality of the bending method will directly affect the processing cost. First we must understand the choice of machine tools and molds:
The choice of CNC Hydraulic Press Brake Machine tool: The tonnage of the machine tool is determined according to the thickness of the material, the bending shape, and the peripheral size. The nc hydraulic press brake tool (including CNC and non-CNC machine tools) to be used is selected on the premise of considering the convenience of operation and high efficiency.
2. The choice of NC Press Brake mold:
① Upper die selection steps:
a. According to the bending shape of the material, determine the several molds that can be used.
b. According to the material diagram, see if you need to match the mold or give way, and determine that there are several types of these molds that can meet the requirements.
c. Finally, consider the convenience and safety of the operation when bending. According to the above points, the upper mold to be used can be determined.
② Lower mold selection steps:
a. The slot width is determined according to the plate thickness (t), as shown in the table:
b. According to the bending shape and size of the material, determine the height dimension of the lower die used and the size of the slot used to the edge of the lower die.
c. According to the bending shape of the material, determine whether it is necessary to match the mold or give way.
According to the above points, the lower die to be used can be determined.
Second, the review of the drawing: through the above understanding of the selection method of NC Hydraulic Press Brake Machine tools and molds, we must determine a reasonable processing technology and formulate the correct bending process file (picture SOP/SIP) when reviewing the bending chart, To facilitate on-site operations.
1. According to the material, material thickness, total length and tolerance requirements of the manufactured parts, determine whether our existing equipment and molding tools are capable of processing and whether it is necessary to open the mold.
2. According to the bending shape and size of the manufactured parts, determine the processing method (bending or mold opening)
1) Whether the existing mold can be bent, if not, according to the actual assembly relationship of the product, contact the customer to decompose the material into several parts, process them separately, and then combine them. If it can't be decomposed for other reasons, it will be opened.
2) After the mold is selected, determine the best bending sequence (the least number of mold replacement and material handling, the safest operation).
3) For small edges that cannot be bent using the standard lower die, you can increase the expansion size appropriately during the expansion calculation process, or you can increase the folding size after obtaining customer consent without affecting the product function.
3. When there are conflicts between bending, rivet, tearing, tearing, etc. on the parts, the reasonable processing procedures must be indicated.
4. When there is a situation where the hole position is too close to the folding edge (that is, the hole will be deformed after bending), you can first open a small hole to be bent
Then expand the hole to the standard aperture.
5. According to the actual assembly relationship, mark the tolerance on the bending dimension of the part drawing.
6. When formulating the SOP, clearly indicate the sheet metal press brake tool and mold used, indicate the bending shape and size of each knife, and indicate the need
The guaranteed key size determines the crease level requirements, and the areas to be protected on the map must be clearly marked.
3. The unfolded shape of the material is the prototype of the product. It should not only be correct but also take into account the actual processing technology and the convenience of the on-site operation staff. The following points of CNC Hydraylic Press Brake must be made to draw a good unfolded drawing:
1. Choose the appropriate drawing format according to the size and complexity of the material.
2. Understand the material and thickness of the material to be developed, and determine the expansion coefficient to be used.
3. Understand the view direction of the part drawing (that is, determine the angle of drawing for the view).
4. Understand the assembly relationship of the material and determine the front and back sides and the direction of the burr.
5. According to the requirements of the drawing and the way of the surface of the material, determine a reasonable tolerance. Generally, the electroplated parts can be expanded according to the dimensions shown in the figure. If it is a paint part, the negative difference in the outer dimension and the positive difference in the aperture.
6. According to the bending process and CNC tool, determine a reasonable process slot, hole and hemming method and gap.
7. For the holes in the material, try to use the company's existing tools. In special cases, you can contact the customer to confirm the changes. If you can't modify, open the special tools.
8. The special bending angle and R angle must be determined by experiment to find out the accurate bending coefficient.
9. The molding part of the mold must be marked with a non-zero layer line to identify the exact position. If it cannot be accurately marked, the words "The size of the molded part shown in the figure is only for reference" must be indicated in the technical requirements.
10. For the directions of pressure riveting, flanging, tearing, punching, etc., the front and back sides must be pointed out, and if necessary, the section drawing should be drawn.
11. For the parts that are easy to be bent and wrong, a schematic diagram of bending must be drawn.
12. The left and right (up and down) asymmetric parts should be marked with text to prevent folding.