Office Chair Tube Welding

Office chair tube welding requires adherence to standardized procedures for material preparation, structural processing, welding operations, and surface treatment. The specific steps are as follows:

I. Material and Tool Preparation

1. Square Tube Selection: Commonly used specifications include 20×40mm or 30×30mm square tubes with a thickness of 1.2-2.0mm, chosen based on the chair's load-bearing requirements. For example, conventional dining chair legs can use 30×30mm square tubes, while seat frames can use 20×40mm square tubes.
2. Welding Materials: Low-carbon steel square tubes should be paired with J422 welding rods to ensure the weld strength matches that of the base material.
3. Auxiliary Tools: Angle grinders (for cutting and grinding), DC electric welders (with adjustable current), bench vises (for fixing and assembling), tape measures and marking pens (for dimension marking), sandpaper (for removing burrs), rust removers (for surface cleaning), and paint or spray-coating equipment (for corrosion protection).

II. Preliminary Preparation and Safety Protection

1. Safety Configuration: When welding, wear a welding helmet, insulating gloves, flame-retardant work clothes, and safety shoes to prevent arc burns and electric shocks. Clear flammable materials within 10 meters of the work area, equip with fire extinguishers, and ensure good ventilation.
2. Drawing Confirmation: Draw cutting dimension diagrams based on the chair's design, specifying the dimensions of the chair legs, crossbeams, and seat frames. For example, conventional dining chair legs are typically about 45cm long, with a 40×40cm square seat frame.

III. Structural Cutting and Assembly Welding

1. Square Tube Cutting: Use an angle grinder or tube cutter to cut parts according to the drawings. The cut edges should be ground smooth and burrs removed to avoid welding porosity.
2. Positioning Assembly: Fix the chair legs, crossbeams, and seat frame in alignment using a bench vise. Use spot welding for positioning (2-3 spots per location) to ensure structural stability without misalignment.
3. Full Weld Reinforcement: Use a DC electric welder with the current set to 80-120A (adjusted according to the square tube thickness). Perform continuous full welding along the spot-welded positions, with a weld height of 3-5mm. After welding, grind down weld beads and slag with an angle grinder.
4. Detail Welding: Focus on reinforcing stress points such as backrest supports and armrests, checking for incomplete welds or cracks.

IV. Surface Treatment and Corrosion Protection

1. Rust Removal and Grinding: Use a wire brush and sandpaper to clean oxidation scales from the welded areas and square tube surfaces, then wipe away residual rust with a rust remover.
2. Cleaning and Dust Removal: Use compressed air or a damp cloth to remove dust, and allow to dry before coating.
3. Coating Operations: For painting, apply 2-3 even coats with a 10-15 minute interval between coats. For spray coating, high-temperature curing is required for better durability.

V. Installation, Debugging, and Finalization

1. Component Installation: Fix components such as chair wheels and cushions.
2. Structural Inspection: Shake the chair to test stability, re-weld loose welds, and adjust misaligned parts.
3. Final Cleaning: Wipe away residual coating from the surface to complete the final inspection.