Deformation of Iron Plate in Office Chairs

Deformation of the iron plate in office chairs can be repaired through methods such as mechanical straightening, thermal straightening, hammering straightening, hydraulic straightening, or electromagnetic pulse straightening. If the deformation is due to structural looseness, tightening the components or re-welding for reinforcement may be necessary.

I. Methods for Straightening Deformed Iron Plates

1. Mechanical Straightening (Cold Straightening)
   Suitable for mild deformations with a thickness of ≤10mm (flatness deviation <2mm/m). Fix the iron plate on a straightening platform and apply slow pressure using a screw press or roller press, controlling the pressure within 70%-90% of the material's yield strength (e.g., 50-100MPa for Q235 steel). Gradually increase the pressure in 3-5 steps to avoid secondary deformation. This method restores the flatness of the iron plate through plastic deformation and is suitable for small-scale repairs.

2. Thermal Straightening (Flame Straightening)
   For moderate to severe deformations, locally heat the iron plate to 300-600°C (for low-carbon steel) or 400-700°C (for medium-carbon steel) using an oxyacetylene flame, with the heated area not exceeding 30% of the deformed region. After heating, control the cooling rate with water or air cooling, and do not repeat heating the same location more than twice to prevent grain coarsening (refer to GB/T 19866-2005). Thermal straightening eliminates internal stresses through the principle of thermal expansion and contraction, but requires strict control of temperature and cooling conditions.

3. Hammering Straightening
   Suitable for small-scale dents in thin plates (<3mm). Use a copper or nylon hammer to strike from the periphery of the deformation towards the center with an impact energy of 0.5-1.5J, maintaining a spacing of 10-15mm between each strike. The hammering should be evenly distributed to avoid excessive local deformation, making it suitable for quick repairs of minor dents.

4. Hydraulic Straightening
   For large components (such as automotive chassis parts), use a hydraulic jack for stepwise loading. Calculate the pressure based on the material thickness: for a thickness of 5-10mm, apply a pressure of 10-20 tons and hold for 3-5 minutes; for a thickness of 10-20mm, apply a pressure of 20-50 tons and hold for 5-8 minutes. Hydraulic straightening gradually restores the shape of the material through sustained pressure and is suitable for repairing complex structures.

5. Electromagnetic Pulse Straightening
   An emerging technology that utilizes instantaneous electromagnetic force (5-10KA current, pulse time of 50-100μs) to rapidly form the material with an accuracy of up to ±0.1mm (data source: JPCL 2023 research report). This method is suitable for high-precision aviation components but has high equipment costs and is rarely used for repairing ordinary office chairs.

II. Handling Structural Looseness or Support Issues

If the deformation of the iron plate is caused by structural looseness or support failure, inspect the fastening components:

1. Use a wrench or screwdriver to tighten the screws and nuts at the connections between the chair legs, seat, and backrest. Replace with new screws of the same specification if they are stripped.
2. If there are cracks at the welded joints, confirm whether the chair is a welded structure. The cracks should be re-welded and reinforced by professionals, and anti-rust treatment (such as spraying anti-rust paint) should be performed after welding.

After repair, test the stability of the chair to ensure there are no abnormal noises or wobbling.