Office Chair Spring Assembly
The spring assembly of office chairs mainly consists of gas springs, and the key points of their structure, testing, inspection, and experimentation are as follows:
1. Gas Spring Structure and Working Principle
A gas spring is an elastic element that uses high-pressure nitrogen as its working medium. Its core components include a cylinder, piston, piston rod, seals, and a guide sleeve. Office chairs commonly use a lockable structure, enabling height adjustment by moving a handle: when the handle is pressed, the valve stem opens, allowing gas to flow between the two chambers inside the cylinder, enabling the piston rod to move; when released, the valve stem resets, closing the passage and locking the gas spring at the current height. Its supporting force comes from the gas pressure difference inside the cylinder, creating a stable force value through the piston's separation.
2. Testing Objects and Scope
Testing covers individual gas springs, lifting column assemblies, and the entire chair. For individual gas springs, the focus is on supporting force, sealing performance, and lifespan; for assemblies and the entire chair, the focus is on smooth lifting, abnormal noises, and the fit quality with the seat and chassis. Additionally, the physicochemical properties of key component materials (such as the coating on the piston rod, the steel of the cylinder, and the rubber seals) must be tested to ensure they are corrosion-resistant, wear-resistant, and meet strength requirements.
3. Sample Collection and Conditioning
Sampling should be randomly selected from the same batch of products, with the quantity following product standards. Samples should be packaged intact, unopened inventory items with labels matching the inspection request. Before testing, verify the nominal force code, stroke parameters, and mounting interface type to ensure they match the drawing requirements. Samples should be placed under standard environmental conditions until temperature equilibrium is reached, removing individuals with appearance defects (such as dents, rust, or oil leaks) and recording group numbers to avoid data confusion. Conditioning eliminates interference from transportation vibrations and temperature differences on measurement results; testing without conditioning may lead to force value drift, affecting judgment conclusions.
4. Appearance and Dimensional Inspection
Appearance inspection combines visual and tactile methods to check the uniformity of coatings/plating, looking for sags, bubbles, scratches, and rust spots; the working surface of the piston rod must be smooth without dents, and welds and closures should be free of cracks. Dimensional inspection covers the outer diameter of the cylinder, the diameter of the piston rod, overall length, stroke, and the center distance of the mounting interfaces at both ends, using vernier calipers, micrometers, and specialized gauges for measurement, with surface roughness evaluated using a roughness tester. Mounting method inspection includes interface coaxiality and connection clearance; loose interfaces can cause chair wobbling, while center distance deviations may lead to improper installation or restricted stroke. During maintenance or replacement, verify parameters and disassemble/assemble in the order of the connection structure to avoid damaging the sealing surfaces.
5. Force Characteristics and Sealing Performance Tests
Force characteristic tests are conducted on a gas spring performance tester or electronic universal testing machine, compressing and returning the piston rod at a constant speed while synchronously collecting force data to analyze supporting force stability. Sealing performance tests detect gas leakage by applying pressure or prolonged static placement to ensure seal reliability, preventing supporting force decay or oil leakage during use.
