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Analysis of Precision Sheet Metal Processing Technology

  • source:metmac;
  • Time:07/29/2021

Due to its open form, simple manufacturing process, and high manufacturing efficiency, sheet metal parts are gradually being used in the racks and structural parts of food machinery and become an industry trend.
Medium and thick plate sheet metal is widely used in this field, but medium and thick plates are greatly affected by the material thickness, bending process, welding process, etc., usually there will be relatively large gaps after forming, resulting in increased welding deformation. Large, so that the size and shape tolerance of the parts cannot be guaranteed, and even welding defects will affect the appearance and quality of the product. Secondly, the processing of medium and heavy plates has some technological difficulties. In order to overcome the technical difficulties, the sheet metal craftsmen of our company have summarized a set of effective methods to solve the problems of plate metal processing, and I will share them with you here.

Analysis of Mid-plate Sheet Metal Process

Let's first look at the example. Figure 1 shows the fixed bracket of a certain product of our company. The material is brushed SUS304 and the thickness is 4mm. Next, we will discuss how it achieves precision machining.

 

 

Analysis of parts quality requirements

(1) First of all, to ensure the flatness of the reference plane A and the perpendicularity of the plane A to the planes B and B is the key to satisfying the assembly shape and position relationship and ensuring the accuracy of the machine position.
(2) Emphasizing the accuracy of bending, it is necessary to ensure the relationship between the horizontal dimensions of B and B, the relative dimensions implied by the fixed bracket, and the dimensional accuracy of the product.
(3) Form and position accuracy and dimensional accuracy are closely related to processes such as blanking, leveling, bending, and welding.

 


Sheet metal process analysis


(1) Sheet metal process control mainly emphasizes the correctness of the process. The reasonable sheet metal process flow of this part is: raw material (drawing plate with better flatness)-laser cutting , leveling, process (key process control)-welding.

(2) The second step is to control the welding deformation to ensure the accuracy of the parts.

  • The traditional process is to use SolidWorks drawing method, normal expansion, bending, welding, the result is that the gap between the parts is very large, and the amount of wire filling is large during welding. Everyone knows that the deformation of stainless steel after welding will be greater, which will lead to parts after welding. The deformation cannot be controlled, and it is impossible to produce qualified products that meet the requirements of assembly accuracy. The part gap is shown in Figure 2.
  • Our method is to use drawing software to expand this part, add slices at C, E, F, control the maximum gap after welding to 0.2~0.3mm, and use manual chamfering machine or polishing machine before sheet metal bending Remove excess base material, so as to achieve precision machining of parts. As shown in the red circle shown in Figure 3.

(3) Explanation of results.

  • The round hole of the part process should be larger. In the food machinery industry, welding is not required, but it is more conducive to the cleaning of the machine.
  • Use a three-dimensional flexible platform to ensure the shape and dimensional accuracy of the workpiece, and argon arc welding is used to bond the welding parts at multiple points. After the workpiece is fixed, the parts can be taken off to complete the free welding, which can effectively save time.
  • During welding, since the product gap is very small, the welding wire can be used instead of the self-fusion method. After welding, the texture is beautiful and does not need to be polished. It not only improves the efficiency and the surface quality of the product, but also the key is that the small gap parts are not welded. Shrinkage occurs, the parts are basically non-deformed, no need to increase the shaping process, and can meet the technical requirements at one time.

Analysis of sheet metal process for medium and heavy plates

In structural design, we often encounter welding methods where the bending R angle is connected with different material thicknesses. Due to the large R value, there are many welding fillers, which will generate greater heat and shrinkage. Generally, the structure of the part is modified, such as Right-angle welding is changed to flat butt welding to complete the precision machining of medium and thick plates, as shown in Figure 4.

 



Comparison of structural advantages and disadvantages: After optimization, welding is easy to achieve, welding deformation is small, no grinding process is required, and the appearance is smooth and beautiful, which improves efficiency and saves costs.

The welding process of medium and thick plates can also be realized through the sheet metal bending process. The thickness of the plate is 8mm, and the material is double-sided drawing SUS304. The original design requires welding of the side plates. After the structure is changed, the welding is changed to bending, as shown in Figure 5.