What is a sheet metal part? Sheet metal part is a comprehensive cold working process for metal sheet (usually less than 6mm), including cutting, punching/cutting/compounding, folding, welding, riveting, splicing, forming and making parts.
Features:
1. Uniform thickness. For a part, the thickness of all parts is the same.
2. Light weight, high strength, conductivity, low cost and good mass production performance.
Processing technic
1.Cut
The equipment of the shearing process is a shearing machine, which can cut a metal sheet into a basic shape. The advantages are: low processing cost; Disadvantages: the accuracy is average, the cutting has burrs, and the cutting shape is simple rectangle or other simple figures composed of straight lines.
The unfolded size of the parts must be calculated before the shearing process. The unfolded size is related to the bending radius, bending angle, sheet material and sheet thickness.
2. Punch
The punching equipment is a punch, which can further process and shape the cut materials. Stamping various shapes requires different dies. Common dies include round holes, oblong holes and bosses. The accuracy is high.
Boss: The material will not be removed. Note that the height of the boss is limited, which is related to the material, thickness and slope angle of the boss.
There are many kinds of bosses, including cooling holes and mounting holes. Due to the influence of bending, the distance between the edge of the design hole and the plate edge and the bending edge will be limited.
3. Laser cutting
Processing equipment: laser cutting machine
For materials that can’t be removed by shearing and punching processes, or plates with high hardness that are easy to damage the mold, such as rounded corners, or there is no ready-made mold to punch the required shape, laser cutting can be used to complete the forming of materials before bending.
Advantages: cutting without burr, high precision, and can cut any pattern, such as leaves, flowers, etc. Disadvantages: high process cost.
4. Bending
Processing equipment: bending machine, plate bending machine
They can fold or roll the metal sheet into the required shape, which is the forming process of parts; The process of cold pressing the metal sheet by the upper knife and the lower knife of the bending machine to deform it and get the required shape is called bending.
Bending is the last step in the forming of sheet metal parts. Some points that should be paid attention to whether the parts can be unfolded and bent are discussed in the following small series.
a. Lack of materials. As shown in the following figure, the boss is too high, which exceeds the ductility of the material. The boss is generally used to increase the installation size or avoid installation conflicts, so the boss must be made without changing the internal structure of the material and affecting the structural strength. For example, the angle between the conical surface of the boss and the reference plane is 45, and the height is 3 times of the plate thickness.
b. Redundant materials: Redundant materials often have multiple folded edges, mostly due to process errors or drawing errors.
c. Bending restrictions: Most bending machines have certain restrictions on bending.
Unilateral height: depending on the size of the bending machine and the height of the upper knife, the solution can be multilateral large-angle bending.
Bilateral height: not greater than the maximum height of a single side, which is restricted by the bottom edge as well as the height of a single side: bending height < bottom edge.
d. Because the sheet metal part is formed by bending a metal sheet, the contact of the bent edge is not sealed and there is no rigid connection. If it is not treated, the strength will be affected. Usually, the treatment method is welding. The technical requirements on the drawings are: welding angle, welding angle and rounding.
e. Surface treatment: because the sheet of sheet metal parts is thin, it is not suitable for hot dip galvanizing. The common surface treatment methods are phosphating and electrostatic spraying, and the color varies with the project. This process is suitable for black parts with untreated surfaces.