The design needs to consider what is the pre-molding processing and what is the post-molding processing.
Considering that during the work manufacturing process, it is necessary to bend first, and then process some holes:
The round holes, square holes, waist round holes, threads, etc. that are very close to the bending edge need to be processed during blanking. If you directly press the unfold blanking, it will not be completed in the subsequent processing, and the waist circle will be bent When the hole is pulled, the threaded hole cannot be tapped with a common tap.
The design needs to consider which ones can be formed by sheet metal and which ones cannot be formed by sheet metal.
To consider the minimum bending height: (as shown below)
The minimum bending radius should be considered: the minimum bending sheet metal depends on the bending radius of the sheet metal material, and the minimum bending radius of common sheet metal materials is shown in the table below.
It is necessary to consider whether the machine tool can be directly used for positioning . If not, two small squares are reserved for positioning and removed after bending.
Consider the bending direction of sheet metal : especially non-ferrous metals, such as aluminum plates, and copper plates. It depends on the grain direction of the material rolling, and the bending should be perpendicular to the grain direction, not parallel to the rolling grain direction, so it is easy to have bending cracks.
It is necessary to reserve a bending avoidance gap : when sheet metal is bent and hemmed, the two bending surfaces have a relationship between the hemming and the hemming. When making the expansion diagram, draw the bend avoidance gap. Because when bending to 90 degrees, the sheet metal will rebound after bending. In order to avoid less than 90 degrees after the rebound, it is necessary to bend more than 90 degrees to offset the rebound. Therefore, it is necessary to reserve a gap for bending and rebound avoidance.
Accumulative error of sheet metal multiple bending : sheet metal bending accuracy is not very high, generally controlled within 0.2mm. The greater the bending height, the lower the bending accuracy. When there are mounting holes, threaded holes, rivet screws, and rivet nuts on the bending surface, the cumulative processing error should be fully considered. The installation hole is enlarged or the installation hole is designed as a waist hole, etc., to avoid installation errors. It is convenient for subsequent installation.
It is necessary to consider the problem of sheet metal rivet screws or rivet nuts , the distance between the hole and the bending edge is too small: when bending, there is bending deformation and tensile deformation at the same time. If holes and notches are too small from the bending edge, the holes and notches will be stretched and deformed. Generally, when the bending edge is 4.5 times the material thickness, there will be no bending deformation problem.
The above is the problem of sheet metal bending that needs to be considered in sheet metal design. Sheet metal design needs to fully consider the bending process and understand the bending process. The design is to be able to be processed into products. The limitations of the sheet metal bending process cannot be ignored.
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