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Precision Control and Improvement Measures for Forming Process of Complex Sheet Metal Parts
2025-06-13
The forming process of complex sheet metal parts is widely used in aerospace, automobile manufacturing, electronic equipment and other fields, and has extremely high requirements for the dimensional accuracy, shape accuracy and surface quality of the parts. Due to the springback effect, anisotropic deformation, mold elastic deformation and thermal stress of sheet metal materials, the geometric accuracy after forming is difficult to strictly control, resulting in assembly errors and unstable quality. Studying the factors affecting forming accuracy and optimizing the process control strategy are crucial to improving manufacturing quality.
Traditional sheet metal processing mainly relies on mold accuracy and process experience, but this method is costly and inefficient, and it is difficult to meet the high-precision requirements of complex structures. In recent years, the development of technologies such as finite element analysis (FEA) simulation forming, springback compensation algorithms, and adaptive process control has provided a scientific basis for precision optimization. The application of intelligent measurement and error compensation strategies makes the forming process more controllable and improves the consistency and assembly accuracy of parts.
This paper will analyze the key factors affecting the precision of complex sheet metal parts, evaluate the applicability of existing control methods, and combine advanced simulation and intelligent manufacturing technologies to propose optimization strategies to provide theoretical support and practical guidance for high-precision sheet metal forming.
Key issues of precision control in the forming process of complex sheet metal parts
1.Analysis of error sources in the process
（1）Material properties ：Sheet metal materials are usually supplied in the form of coils or plates, and have uneven thickness. Even in the same batch of materials, there will be slight fluctuations in thickness. This unevenness will cause different stresses or deformations in certain areas of the material during processing, thus affecting the final shape and dimensional accuracy of the part. The elastic modulus of a material is an important parameter that describes the stiffness characteristics of a material when subjected to force. Different materials or different batches of the same material will have different elastic moduli, resulting in different elastic deformations during the forming process. Some sheet metal materials, especially cold-rolled steel plates or aluminum alloy plates, will have obvious anisotropy, that is, differences in mechanical properties in different directions. This characteristic will cause the material to deform differently in different directions, thereby affecting the accuracy of the part.
(2) Process equipment accuracy and tool wear： The accuracy of processing equipment directly affects the dimensional accuracy of the forming process. For example, the accuracy of laser cutting machines, stamping machines and CNC machine tools will decrease during long-term use. The positioning accuracy, stability and dynamic response ability of the equipment will affect the processing accuracy, resulting in deviations in part size. In the long-term forming process, tool wear will directly affect the processing accuracy. Especially in processing methods such as stamping and shearing, the sharpness, shape and surface condition of the tool will change with the increase in use time, resulting in dimensional deviations during the processing process. Tools with severe wear will cause the surface roughness value of the part to increase or the dimensional accuracy to be unstable.
(3) Environmental factors such as changes in temperature and humidity：Changes in temperature can cause thermal expansion or contraction of materials, thereby changing the size of parts. In addition, the movement accuracy of the equipment will also change at different temperatures. For example, in a high temperature environment, the guide rails of the equipment will deform slightly, resulting in positioning errors. A high humidity environment will cause the material to absorb moisture and expand, thereby changing its mechanical properties and dimensional stability, especially in wood, plastic or certain metal materials. In addition, humidity will also affect the electronic components and mechanical structures of process equipment, resulting in reduced equipment accuracy.
2.Common accuracy issues and their impacts
(1) Dimensional deviation: Dimensional deviation refers to the deviation in length, width, thickness, aperture and other dimensions, which directly affects the assembly and function of parts. If the dimensional deviation of sheet metal parts is too large, it will lead to assembly difficulties or even impossible assembly. Especially for parts that need to fit tightly, inappropriate dimensions will lead to excessive gaps or interference, affecting the overall quality of the product.
(2) Shape error: Shape error mainly includes straightness error, flatness error and roundness error. Shape error will cause the parts to fail to maintain the expected geometric relationship during assembly, affecting the positioning and fit of the parts. For parts with large forces, shape error will cause stress concentration, making the parts prone to deformation or fatigue failure during use. Some application scenarios have strict requirements on the geometric shape of parts, such as the housing or supporting structure in precision instruments. Any slight shape error will cause functional failure.
(3) Surface quality issues: Surface quality issues mainly include excessively high surface roughness values of parts, surface defects such as scratches, pits or uneven coatings. Excessively high surface roughness values will increase the friction between parts, causing increased wear of moving parts and reducing the service life of parts. For parts that need to be sealed, such as valves and pipe connection parts, the surface quality directly affects the sealing effect. Uneven surfaces or scratches will lead to poor sealing, which in turn causes leakage or penetration, affecting the overall performance of the product.
Improvement measures for Industrial Precision control of complex sheet metal parts forming
1. Improve the forming process design
Optimizing forming process parameters is an effective way to improve product quality and reduce costs. Reasonable selection and adjustment of process parameters, such as pressure, temperature, speed and time, can significantly improve the forming effect of parts, reduce defects, and ensure that products meet design requirements. In stamping, pressing and other processes, too low pressure will cause the parts to fail to form completely, while too high pressure will cause excessive deformation or damage to the material. Too high or too low temperature will also affect the plasticity and formability of the material, so it is necessary to select a suitable temperature range according to the material properties. Appropriate forming speed can avoid cracks or uneven thickness changes in the material during the forming process, while improving production efficiency. Too large a gap will cause too many burrs on the edge of the part, and too small a gap will cause the material to fail to flow smoothly and cause cracking. Therefore, a reasonable mold gap is the key to ensuring forming accuracy.
Finite element analysis can simulate the flow of materials, stress distribution, and temperature changes during the forming process, and predict possible defects such as material cracks and wrinkles. The simulation results can provide a basis for optimizing process parameters, such as adjusting pressure and mold design. Using professional forming process simulation software, it is possible to accurately simulate the plastic deformation process of materials during the forming process, predict the deformation behavior of parts, optimize mold design and process parameters, and achieve the purpose of improving forming accuracy and product quality. Through simulation, potential problems in mold design can be discovered in advance, reducing mold adjustment and improvement work in actual production. For example, simulation can help optimize the cooling system and exhaust design of the mold to avoid problems such as thermal stress and uneven temperature.
2. Application of high-precision forming equipment
The introduction of CNC technology has greatly improved the accuracy and automation level of sheet metal processing. CNC punching machines can automatically select appropriate processes, speeds and pressures for punching, cutting and other operations according to design drawings. CNC bending machines can ensure accurate forming of parts by precisely controlling the bending angle and position, reduce manual intervention and improve production efficiency. The introduction of automated welding equipment, such as robotic welding systems, can ensure high consistency and accuracy of the welding process and avoid deviations caused by manual operation. Robotic welding systems achieve stable welding quality through precise trajectory planning and welding parameter control. With the development of automation technology, automated assembly lines have also been widely used in the production of sheet metal parts. Through automated assembly, the assembly position of parts can be precisely controlled, human errors can be reduced, and assembly accuracy and consistency can be improved.
Complex sheet metal parts have diverse geometric shapes and need to be formed multiple times through various processes such as bending, folding, punching and stretching. Their complex shapes include curved surfaces, special-shaped edges, concave and convex changes, and nested holes. They require not only precise shapes, but also high appearance and functional standards. The manufacturing process requires extremely high dimensional accuracy, and any deviation may affect the assembly accuracy and even the overall quality of the product. Material selection needs to consider factors such as mechanical properties, corrosion resistance and heat resistance. At the same time, surface quality is also crucial. The surface roughness and glossiness must be guaranteed to meet the appearance and durability requirements.
3. Material selection and optimization
Selecting materials with uniform organizational structure, such as uniform metal grains or high molecular polymers, can ensure uniform stress distribution and deformation during the forming process. Materials with uneven organization are prone to local stress concentration during the forming process, resulting in part shape deviation and inaccurate size. The chemical composition stability of the material will also affect the accuracy of the forming process. For example, materials containing a high proportion of impurities or easily oxidized will undergo chemical reactions during the heating process, changing their properties. Selecting materials with higher chemical stability can reduce errors caused by fluctuations in material composition. Before forming, the surface treatment of the material also affects the processing accuracy. Materials with rough surfaces or tiny cracks are prone to uneven deformation or damage during the forming process, affecting the forming accuracy. Therefore, materials with smooth surfaces and no obvious defects should be selected to ensure uniformity during the processing process.
High-strength materials can better resist external forces during the forming process and reduce errors caused by excessive deformation. For example, choosing high-strength steel or high-strength alloy materials can avoid excessive deformation during forming processes such as stamping and stretching, ensuring dimensional stability after forming. Low-deformation materials usually exhibit a smaller elastic modulus and higher yield strength, allowing them to maintain better shape and dimensional stability during processing. For example, aluminum alloys, titanium alloys, and certain special plastics exhibit lower plastic deformation during the forming process, which can reduce forming errors.
4. Process parameter optimization
By designing different test plans, adjusting the relevant parameters of stamping, bending and other processes, observing product quality, precision and defects in the forming process, and through systematic experiments, the influence of various parameters on the forming effect can be obtained to provide data support for further optimization. By collecting and analyzing test data, regression analysis, variance analysis and other methods can be used to reveal the quantitative relationship between process parameters and product quality. Through data modeling, the parameter settings of stamping, bending and other processes can be optimized to reduce process errors and improve product consistency. According to the results of experiments and data analysis, the optimal parameter combination of stamping, bending and other processes is determined, such as adjusting the gap, speed and punching force of the die during stamping, optimizing the parameters such as the radius of curvature, bending speed and material tension during bending, and ensuring that the size and surface quality of the product are optimal.
In summary, in the forming process of complex sheet metal parts, factors such as material uniformity, forming equipment accuracy, process parameter optimization and real-time feedback control jointly affect the final forming accuracy. By optimizing process parameters such as stamping and bending, introducing high-precision equipment such as Cnc And Laser cutting, and using high-strength and low-deformation materials and feedback control systems, the forming accuracy can be significantly improved. In addition, the application of simulation technology and artificial intelligence provides a new direction for precision control.