When processing thin-walled parts, spin welding machines require multi-dimensional process control to address deformation and burn-through. Key to this is precise heat input management, optimized clamping methods, and adjusted welding sequences. Thin-walled parts, due to their thin material thickness and low heat capacity, are susceptible to localized overheating during welding, leading to uneven metal expansion and, in turn, wave-like or angular deformation. Burn-through is directly related to excessive heat input. By dynamically adjusting welding parameters and mechanical constraints, spin welding machines effectively balance heat distribution and structural rigidity.
Controlling heat input is key to preventing burn-through. Spin welding machines utilize a combination of low current and high welding speed. For example, when the base material thickness is less than 2 mm, intermittent welding techniques using argon shielding are used, with spot weld intervals maintained at 30-50 mm and single spot weld lengths not exceeding 30 mm. Furthermore, sensors monitor the base material temperature in real time. When the temperature exceeds 150°C, welding is suspended and supplemental heating is applied from the side to maintain weld pool stability and avoid heat concentration. For medium and thick plates, a hot air blower can be used to uniformly preheat the workpiece to approximately 60°C before welding to reduce thermal stress, but the preheating range must be strictly controlled to prevent excessive softening.
Optimizing the clamping method can significantly improve structural rigidity. Spin welding machines often use modular fixtures to secure the workpiece to the assembly table, focusing on restraining the outer edges and deformation-sensitive areas. For example, a magnetic platform with multi-point, multi-stage suction and pressure is used for plate-shaped parts, and long cantilever structures are equipped with three-point movable support clamps to prevent gravity sagging. When welding complex curved surfaces, a sectional contoured jig can precisely secure the workpiece and reduce movement during welding. In addition, rigid components should be tempered after welding before disassembly to avoid residual stress release and deformation.
Adjusting the welding sequence and path can disperse heat accumulation. Spin welding machines should adhere to the principle of "welding the side with greater shrinkage first." For example, when welding flat surfaces, two people should weld symmetrically from the center to the left and right. For fillet welding, first complete the base weld of the main load-bearing weld seam before adding the decorative finish. For long straight seams, it is recommended to use reverse segmented step-back welding, with each segment length limited to 80 mm. For multi-layer welding, the thickness of each layer should not exceed one-third of the plate thickness, and the interval between layers should be completely cooled before continuing welding. When welding dissimilar materials, the thermal conductivity of the base material must be matched. If the thermal parameters differ by more than three, a vacuum cladding process should be used instead.
Reserving shrinkage compensation is an effective means of combating deformation. When splicing plates, a 2%-4% shrinkage allowance should be allowed. The specific amount should be adjusted based on the material. For example, the compensation ratio can be increased appropriately for aluminum alloys. For workpieces with anticipated deformation, a pre-fabricated anti-deformation tool can be pre-fabricated, pre-bending 5-8 degrees to allow for compensation. This allows the post-weld shrinkage stress to offset the anticipated deformation. After completing a single weld, the dimensional deformation should be immediately checked. Any areas exceeding 0.8 mm should be flamed to eliminate local stress, and the tooling should be fine-tuned in reverse to compensate for subsequent deformation.
Peent-peening the weld can release stress within the metal lattice. After welding, use a small hammer to tap the heat-affected zone of the weld at a high frequency and even frequency. This allows metal to stretch and counteract shrinkage deformation. This is particularly useful for correcting wavy deformation after thin plate butt welding. However, it is important to avoid tapping the weld root and cap welds to avoid cracking and affecting inspection results.
When welding thin-walled parts using a spin welding machine, a multi-layered deformation control system is established through a combination of low heat input parameters, precise clamping, a symmetrical welding sequence, reserved compensation, and hammer stress relief. These measures not only effectively prevent burn-through and deformation, but also improve welding efficiency and yield, meeting the high-precision requirements of thin-walled structures in fields such as aerospace and automotive manufacturing.
