In the stamping process of car seat parts, the forming of complex curved surfaces requires a multi-dimensional technological collaboration, encompassing material selection, mold design, process parameter optimization, and the application of auxiliary devices. Complex curved surfaces typically refer to geometric structures characterized by asymmetry, multiple curvatures, and large depth variations. These are prone to defects such as cracking, wrinkling, and springback during forming, necessitating targeted optimization of the process flow.
Material selection is fundamental to forming quality. Car seat parts often use high-strength steel plates or aluminum alloys, requiring a balance between strength and ductility. For example, while high-strength steel improves structural rigidity, its low ductility necessitates improved formability through hot stamping. Aluminum alloys, on the other hand, require solution-treated materials to leverage their good ductility and reduce the risk of cracking. Material thickness and surface quality also require strict control; excessive thinning can lead to localized over-thinning, and surface defects can cause stress concentration.
Mold design is the core of forming complex curved surfaces. The mold surface must perfectly fit the curved surface of the part, and springback must be offset through compensation design. For example, for areas with small radii of curvature, the die needs to use smaller fillet radii to facilitate material flow; for areas with large depth variations, a stepped blank holder surface needs to be designed to ensure uniform blank holder force in each area. Furthermore, the die structure must have sufficient rigidity to prevent deformation under high pressure, which could lead to dimensional deviations in the parts. The placement of draw beads is also crucial; their position and number need to be adjusted according to the material flow characteristics to increase resistance and ensure uniform metal distribution, preventing wrinkling.
Optimization of process parameters directly affects the forming effect. Blank holder force is a key parameter for controlling material flow; too small a force can easily lead to wrinkling, while too large a force may cause cracking. The optimal blank holder force range needs to be determined through simulation analysis and adjusted in real time during stamping. Stamping speed and die temperature also need to be controlled in tandem. While high-speed stamping can improve efficiency, it may cause cracking due to excessively rapid material flow; too low a die temperature will reduce material plasticity and increase springback. For difficult-to-form materials such as high-strength steel, a multi-pass deep drawing process can be used to gradually form complex curved surfaces, reducing the amount of deformation per pass. The application of auxiliary devices can further improve forming accuracy. For example, setting an ejector in the mold can assist in demolding the parts after stamping, avoiding deformation caused by adhesion; using hydraulic or pneumatic cushions instead of traditional spring-loaded blank holders can achieve dynamic adjustment of the blank holder force to adapt to the forming requirements of different areas. For areas with complex local structures, such as flanges or holes, additional process steps can be added, completed through subsequent trimming or punching processes, reducing forming difficulty.
Simulation technology provides important support for process optimization. By establishing a three-dimensional model of the part and simulating material flow, stress distribution, and springback during the stamping process, potential defects can be identified in advance and process parameters can be adjusted. For example, in the optimization of a car seat adjuster side plate, simulation revealed stress concentration in the elliptical hole area; by adjusting the sequence of punching and flanged processes, cracking was successfully avoided. Simulation results can also be used to verify the rationality of mold design, reduce the number of trial moldings, and lower production costs.
Complex curved surface forming requires a balance between efficiency and quality. In mass production, it is necessary to balance process complexity and manufacturing costs. For example, for parts produced in medium batches, a single-row layout scheme can be used to reduce raw material costs by optimizing material utilization; while for mass production, multi-stage forming or automated production lines can be considered to improve production efficiency. Furthermore, mold maintenance and upkeep are also crucial; regularly checking mold wear and repairing it promptly can ensure long-term stable forming quality.
