General principles:
1. The section of the bending part will change in the bending deformation area. The smaller the ratio of the bending radius to the back of the plate, the greater the change of the section shape
2. The bending curve of the bending part should be perpendicular to the direction of the binding. It is best to use the smooth surface of the wool embryo as the outer surface of the bending part to reduce the outer layer cracking
3. Springback will occur during bending. The larger the ratio of bending radius to plate thickness, the greater the springback
Bend radius selection
1. The bending radius of bending parts should be selected appropriately, and should not be too large or too small. The minimum bending radius can only be selected when necessary in structure.
Technological requirements
1. The length, width, thickness and grain direction of the material shall meet the requirements of the drawing; The plate surface is clean.
2. Select appropriate molds according to the drawing requirements and materials.
3. Check the working condition of the bending machine and maintain the equipment before processing.
4. Before and during processing, the bending surface of the die shall be cleaned and lubricated.
Process quality
4.1 appearance
4.1.1 the non machined surface should be kept clean. If the raw materials have surface protective film, it should be retained if it does not affect the processing realization or the accuracy of parts; The degree of surface scratch shall not exceed the provisions of heavy scratch, and the export products shall not exceed the provisions of light scratch.
4.1.2 surface indentation, that is, the periodic or aperiodic concave impression on the surface of the sheet metal, according to the length of the processed sheet metal material ≯ 5 × 10/m。
4.1.3 there shall be no obvious tensile cracks on the bending surface.
4.1.4 the edges of bending corners shall not have cracks. When bending cracks are unavoidable, process holes of appropriate size should be opened at the cracks.
Size
5.1 the relative position, linear dimension and tolerance of structural parts and each opening and groove shall meet the requirements of the drawing, and the unmarked tolerance shall meet the requirements of tolerance grade M.
5.2 the diagonal dimension shall meet the following requirements on the premise of meeting the requirements of linear dimension, shape, position, dimension or tolerance:
a. When the diagonal length is ≤ 550 mm, the difference of its diagonal is not greater than 1.5 mm;
b. If the diagonal length is more than 550 mm, the diagonal difference shall not be more than 3 mm
Shape
6.1 straightness, flatness and perpendicularity are not marked with tolerance class L requirements. 。
6.2 the unmarked tolerance value of parallelism is equal to the given dimensional tolerance value, or the corresponding tolerance value among the unmarked tolerance values of straightness and flatness, whichever is greater.
6.3 other requirements shall be given by drawings or process documents.
Inspection
7.1 the first piece inspection must be carried out before the processing of multiple sheet metal bending parts.
