In the process of precision sheet metal processing in Wuhan, stress concentration is one of the key issues affecting the quality and life of parts. When the local stresses subject to a material are much higher than the average stress, deformation, cracks and even fractures may occur. Especially in thin-walled structures, complex bending or high-precision assembly scenarios, the negative impact of stress concentration is more prominent. How to avoid this problem through process optimization and design adjustment has become the core considerations in the processing process.
Optimize structural design to reduce stress sudden changes
Stress concentration often originates from sudden changes in geometric shapes, such as sharp corners, small holes or sudden cross-sections. During the part design phase, stress distribution can be improved by:
1. Replace right angles with rounded corners: The bend is made of arc transition instead of right angles. The radius is recommended to be greater than 1.5 times the thickness of the material. For example, using rounded corners above R1.5mm for 1mm sheets can significantly reduce the peak of corner stress.
2. Gradient hole design: When opening holes on sheet metal, avoid small holes close to the edge or densely arranged. If necessary, use teardrop-shaped or elliptical holes to make the stress distribution more evenly.
3. Balance between reinforcement ribs and grooves: For areas that require local reinforcement, the load is dispersed through arc-shaped reinforcement ribs instead of simply increasing the thickness to avoid new stress concentration points due to different stiffness.
Material selection and pretreatment process
The properties of the material directly affect stress performance. Metals with better ductility are preferred, such as 5052 aluminum alloy or 304 stainless steel. This type of material can relieve local stress through plastic deformation during molding. For brittle materials such as high-carbon steel, annealing can be performed to eliminate internal residual stress. In addition, laser cutting produces smaller heat-affected zones than conventional stamping, which can reduce the risk of stress concentration caused by edge hardening.
Fine control of processing technology
1. Step-by-step forming strategy: Complex bending parts adopt multiple passages of progressive molding, such as completing 90-degree bends in 3-4 times, and reserve stress release time after each bending, which is more conducive to stress dispersion than single forced molding.
2. Matching mold and equipment: Use a hydraulic bending machine with buffering device to ensure uniform pressure application; polish the surface of the mold and apply special lubricant to reduce material flow resistance.
3. Residual stress elimination: Vibration aging treatment or low-temperature annealing (200-300℃) are performed on the finished parts, especially for welded parts or laser cutting parts.
Testing and verification methods
The stress distribution during the processing is simulated through finite element analysis (FEA) software, identify high-risk areas in advance and adjust the plan. In physical detection, X-ray diffraction can be used to measure the residual surface stress, or microcracks can be found through dyeing and permeability detection. For mass-produced parts, periodic sampling is performed for fatigue testing to verify the stress control effect.
The stress concentration problem in precision sheet metal processing requires full prevention and control from the source of the design to subsequent processing. Through a combination strategy of structural optimization, material adaptation, process improvement and strict inspection, it can not only improve the reliability of parts, but also extend the service life of the product. In actual applications, the solution needs to be flexibly adjusted according to the specific material thickness, shape complexity and usage environment. If necessary, the process flow can be continuously optimized based on experimental data.
