Gas spring

It is a mechanism composed of a closed cylinder, a piston assembly and a piston rod which can slide in the cylinder and takes compressed gas as the energy storage medium.
A cycle
It refers to the air spring piston rod once in the stroke specified in the drawing.
Dynamic internal resistance (g)
It refers to the dynamic friction force produced when the piston rod moves back and forth within the stroke specified in the drawing.
technical requirement
general requirements

The gas spring shall meet the requirements of this standard and be manufactured according to the drawings and technical documents approved by the specified procedures.
The installation length tolerance of gas spring shall conform to grade A of QC / t29087.
The shape of the gas spring should be smooth and smooth without burr.
The coating of air spring piston rod should be uniform, and no visible cracks, blisters, pockmarks, delamination and other defects are allowed.
The coating of other parts except piston rod should be uniform: no local coating, obvious crack, blister, roughness and other defects are allowed.
The coating layer of gas spring should be uniform, and no defects such as exposure, wrinkling, blistering and peeling are allowed.

Working temperature range: 40 ℃~ 80 ℃.
mechanical property
When the air spring is tested according to 5.1, its force displacement curve is shown in Fig. 1. The nominal value of the force shall meet the requirements of the drawing, and the limit deviation of the nominal value of the force shall comply with the provisions in Table 1.
When the piston rod of the air spring is reciprocating, its dynamic internal resistance g shall meet the requirements of the drawing, and no clamping stagnation and obvious vibration are allowed.
Air tightness

Durability
The change rate of initial force value of air spring after 5.3 test shall not be greater than 8%.
Corrosion resistance
After the air spring is tested according to 5.4, the coating of the gas spring shall comply with the provisions of Article 5.2 B in gb6461, and the coating layer of the gas spring shall meet the requirements of grade I in gb1740.
tensile strength
The overall tensile strength of the gas spring shall meet the requirements of Table 2. After the test according to 5.5, all connectors shall not be broken or fall off, and their mechanical properties shall meet the requirements of Table 1.
test method

Mechanical property test
Test conditions: the temperature is 20 ± 2 ℃, and the measurement is carried out after 4 hours. The test speed is 500 mm / min.

Test method: the piston rod of the air spring is vertically clamped on the testing machine with the piston rod downward for at least three cycles, and the piston rod of the gas spring is observed for clamping or obvious vibration. If there is no abnormality, start to measure and record the force displacement curve, and measure the f force at each point according to the following method:
Compress the air spring piston rod to point a according to the distance L specified in the drawing, stay for 3S; record the value of F3 force.
Compress the piston rod of the gas spring to point B and stay for 3S; record the value of F4 force.
Stretch the piston rod of air spring to point C and stay for 3S; record the value of F2 force.
Stretch the piston rod of air spring to point D and stay for 3S; record the value of F1 force.

Air tightness test
The gas spring was placed in a high-temperature test chamber at 80 ± 2 ° C for 4h, then moved to 20 ± 2 ℃ for 2h, and then placed in a low-temperature test chamber at 40 ± 2 ° C for 4h, and then moved to 20 ± 2 ℃ for 2h. After two times of high and low temperature tests, the mechanical properties were tested according to 5.1.

Durability test
The gas spring was loaded on the testing machine according to the actual loading state, and the gas spring was continuously and evenly cycled for 25000 times at the frequency of 4-6 times / min. 2500 times per cycle, test and record according to 5.1.

Corrosion resistance test
The piston rod of the air spring is in the minimum compression state specified in the drawing, and the test shall be conducted for 48h according to the provisions of GB 6458. After the test, the corrosion resistance of 4.5 shall be checked.

tensile strength test
Fix the connection parts of both ends of the gas spring on the testing machine, and apply the tensile test specified in 4.6. After the test, the mechanical properties were tested according to 5.1.