Office Chair Double-Tube Welding

The welding of double tubes for office chairs requires comprehensive control from four aspects: material selection, welding process parameter control, operation specifications, and post-welding treatment to ensure welding quality and structural stability.

1. Material Selection and Suitability

The commonly used materials for welding double tubes in office chairs are Q235 cold-rolled steel plates (thickness 1.5-3mm) and 20 seamless steel tubes (wall thickness 1.2-2.5mm). Both are low-carbon steels with good weldability and high plasticity, suitable for fusion welding. Material selection should be based on the load-bearing requirements of the office chair: for example, chair legs with heavier loads are recommended to use seamless steel tubes with thicker walls, while connecting parts or decorative elements can use thinner cold-rolled steel plates to balance cost and performance.

2. Welding Process Parameter Control

Metal Active Gas Welding (MAG) is the mainstream process for welding double tubes in office chairs, offering advantages such as moderate penetration, high deposition efficiency, and uniform weld formation. Key parameters must be strictly controlled:

• Heat Input Control: Excessive temperature should be avoided to prevent excessive weld penetration or metal overheating. If the heat input is too high, welding deformation (such as frame distortion) may occur after cooling, affecting chair stability; if the heat input is insufficient, unfused defects may form.
• Weld Leg Size Design: The weld leg height should be determined based on load calculations, typically ranging from 0.7 to 1.0 times the thickness of the thinner plate. For example, if the wall thickness of the thinner tube is 1.5mm, the weld leg height should be controlled between 1.05-1.5mm to balance weld strength and total heat input, avoiding local stress concentration.

3. Operation Specifications and Welding Sequence

• Welding Sequence Optimization: For symmetrically structured office chair frames (such as four-legged chairs), it is recommended to weld symmetrically from the middle to both ends or use the skip welding method (welding welds at intervals) to disperse welding stress and reduce overall deformation. If the frame is asymmetrical, priority should be given to welding the more heavily loaded parts before completing the other welds.
• Operation Details: Before welding, the material surface should be cleaned of oil, oxide films, and other impurities to prevent porosity or slag inclusion defects; during welding, the welding torch angle should be kept stable (usually perpendicular to the workpiece or tilted 10°-15°) to ensure uniform weld pool formation.

4. Post-Welding Treatment and Durability Enhancement

After welding, grinding treatment should be performed to achieve a surface roughness of Ra3.2 micrometers or less for the weld, eliminating burrs, splashes, and other defects, improving appearance quality, and reducing stress concentration. Subsequently, a corrosion-resistant coating (such as painting or electrophoretic coating) should be applied to prevent strength degradation in the weld area due to environmental corrosion, extending the service life of the office chair.

By systematically controlling the above steps, high-quality and high-stability welding of double tubes for office chairs can be achieved, meeting daily usage requirements.