JB/T 8064.1-1996Compression gas springs - Technical specifications (English PDF)

6.3.7 Cycle life

Gas springs that have gone through the thermal and cold shock resistance test shall also be able to withstand 20,000 times of cycle life test. After the test, the total attenuation of the nominal force shall be less than 13%; the dynamic friction shall comply with the stipulations of Table 2.

6.3.8 Tensile strength

The gas spring is stretched at 4 times the nominal force and maintained for 5 min; the force performance of the gas spring shall remain unchanged.

The gas spring is stretched at 8 times the nominal force and maintained for 5 min; the gas spring is allowed to fail, but not dismembered.

7.1 Size and Appearance Inspection

7.1.1

Use special or general-purpose measuring instruments with a division value less than or equal to 0.02 mm for size inspection.

7.1.2

Adopt visual inspection or 4 times magnifying glass for the inspection of the appearance quality. The electroplated coating, chemical treatment layer and paint coating shall respectively be inspected in accordance with the relevant regulations of

GB/T 13913, JB/Z 111 and JB 2864; the inspection results shall comply with the stipulations of 6.2.3 ~ 6.2.5.

7.2 Force Performance Inspection

7.2.1 Test conditions

The inspection shall be carried out at 20 °C ± 2 °C. Before the inspection, the gas spring shall be in an environment of 20 °C ± 2 °C, and always be maintained in the stretched state; the piston rod must not be pressed; place it for above 2 h. The measuring speed of the testing machine is: 200 mm/min; the force measurement accuracy of the testing machine is not lower than 1%; the displacement measurement accuracy is not lower than 1%.

7.6 Life Test

On the testing machine, install the gas spring that has been subjected to the thermal and cold shock resistance test. The piston rod is placed downward; control the gas spring to complete cycles; the frequency of the cycles is 4 ~ 10 times/min. During the test, the temperature of the gas spring cylinder shall be lower than 50 °C.

After every 5,000 cycles, in accordance with the inspection method in 7.2, determine the force performance once. After 20,000 cycles, the determination results shall comply with the stipulations of 6.3.7.

7.7 Tensile Strength Test

Fix the gas spring on the testing machine; at a speed of 2 mm/min, load it. Then, in accordance with the stipulations of 6.3.8, conduct the test.

8.1 Inspection Classification

Product inspection is divided into type inspection and exit-factory inspection.

8.2 Type Inspection

Under one of the following circumstances, type inspection shall generally be conducted:

a) Trial production and type appraisal of new products or old products being transferred to another factory for production;

b) After formal production, when there are relatively significant changes in structures, materials and processes that might affect product performance;

c) In formal production, inspection shall be periodically carried out or after a certain amount of output has been accumulated;

d) When production is resumed after a long term of suspension;

e) When there are significant differences between the exit-factory inspection results and the previous type inspection;

f) When the national quality supervision institution requests for type inspection.

8.2.1 Defects

Gas springs that do not comply with the specified technical requirements in product technical standards, process documents and drawings shall constitute a defect. In accordance with the severity of the defects, they may be divided into:

A Defective Item (fatal defect)

B Defective Item (severe defect)

C Defective Item (general defect)

See Table 3 for details.

Table 3

A Defective Item B Defective Item C Defective Item

Resistance to Thermal and Cold Shock

Cycle Life

Tensile Strength

Force

Characteristics

Size and Appearance Quality

Resistance to Neutral Salt Spray

8.2.2 Sampling method

8.2.2.1 Determination of inspection batch

a) The inspection batch must be qualified gas spring products; 500 gas springs constitute one inspection batch. If the number of products is greater than 500, then, the inspection personnel shall randomly divide them into several inspection batches (500 pieces in each batch), then, randomly determine an inspection batch as the object of the random inspection.

b) If the number of products is not more than 50, then, the inspection batch should not be sampled, instead, the stock products shall be selected for sampling.

8.2.3 Sample selection

8.2.3.1

Non-destructive inspection items shall share one sample. If the number of products is greater than 280, then, in accordance with the general inspection level-I specified in GB 2828, the sample size code F and one-time sampling scheme for normal inspection, select 20 gas springs; if the number of products is not more than

280, then, in accordance with the general inspection level-I specified in GB 2828, the sample size code E and one-time sampling scheme for normal inspection, take 13 gas springs as the samples.

8.2.3.2

The inspections of resistance to thermal and cold shock, cycle life and tensile strength shall share one sample. In the same inspection batch, in accordance with the […]

10.1 Product Signs

Each gas spring product shall be marked with the following content in an obvious position:

a) Product name, model or marking;

b) Name of manufacturer;

c) Production date or production batch No.;

d) High-pressure products must not be arbitrarily disassembled;

e) Trademark;

f) Certificate of conformity.

10.2 Packaging Box Signs

The gas spring packaging box shall have the following signs:

a) Product name and model;

b) Manufacturer’s name and address;

c) Number of products in the box;

d) Overall dimensions and gross weight;

e) Exit-factory date;

f) Signs of “Avoid High Temperature” and “Handle with Care”, etc.

10.3 Packaging

10.3.1

Each gas spring product shall be packed in a plastic bag. In the packaging box, there shall be flexible materials between gas springs.

10.3.2

The gross weight of each box shall not be greater than 30 kg.

10.3.3

The packaging box shall be attached with a certificate of conformity stamped by the technical inspection department.

10.3.4 Transportation