Some standard content:
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Lockable Gas Springs
JB/T8064.296
This standard specifies the terminology, marking, technical requirements, test methods, inspection rules, marking, packaging, transportation, storage, etc. of lockable gas springs (hereinafter referred to as gas springs).
This standard applies to gas springs filled with nitrogen or inert gas as working medium. Including angle-adjustable lockable gas springs (hereinafter referred to as angle-adjustable gas springs) and lifting lockable gas springs (hereinafter referred to as lifting gas springs). 2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T1771--91 Determination of neutral salt spray resistance of paints and varnishes GB1800-79 General introduction to tolerances and fits Standard tolerances and basic deviations GB/T2348-93 Hydraulic and pneumatic systems and components Cylinder bore diameter and piston rod outer diameter GB2349--80 Hydraulic and pneumatic systems and components Cylinder piston stroke series GB2828-87 Batch inspection counting sampling procedures and sampling tables (applicable to inspection of continuous batches) GB6458-86
GB 6461-86
Metallic coating neutral salt spray test (NSS test) Metallic coating corrosion test on substrate as cathode coating Rating of electroplated samples after test of autocatalytic nickel-phosphorus coating Technical requirements and test methods GB/T 13913-92
JB2864—81
Electroplating and chemical treatment for automobiles
JB/Z111-86Automobile paint coating
3 Types
3.1 The schematic diagram of the appearance of the angle-adjustable gas spring and the force-displacement curve are shown in Figure 1. The schematic diagram of the appearance of the lifting gas spring and the force-displacement curve are shown in Figure 2. Retraction process
Extension process
Stroke S
Extension length L
Approved by the Ministry of Machinery Industry of the People's Republic of China on October 3, 1996 and implemented on July 1, 1997
3.2 The recommended type of gas spring joint is shown in Figure 3.U-double ears
0)-single ear
4 Terms, symbols and definitions of gas springs
Terms, symbols of gas springs See Table 1 for definitions. 610
JB/T8064.2--96
Compression process
Stretching process
Performance S
Stretching length
S--dimension
M·Thread
Inner diameter of cylinder
Opening force
Rigid locking and
Elastic locking
Locking force
JB/T 8064.2-96
Definition or description
Inner diameter of gas spring cylinder
To release the locked state of the gas spring, the maximum compression force required to press the rod into the opening force is called the opening force. In the locked state of the gas spring, the piston rod under the action of the axial compression force will produce displacement. The compression force displacement characteristic curve is as follows. wwW.bzxz.Net
Axial compression force
Piston rod displacement
Curve 1 is a rigid locking characteristic, with a straight rise section and a yielding platform. Under normal circumstances, the displacement corresponding to the straight rise section is small: 1mm. Curve 1 is an elastic locking characteristic, with a small slope and no yielding platform. The rigidly locked gas spring is locked in the extended state. At this time, the axial compression force required to make the piston rod produce a 1mm displacement is the locking force value. The elastically locked gas spring is locked at the midpoint of the stroke. At this time, the axial compression force required to make the piston rod produce a 4mm displacement is the locking force value. The characteristics of the gas spring in the non-locked state are the same as those of the compression gas spring, so the terms related to the gas spring should refer to JB/T8064.1-96.
5 Marking
5.1 Marking method
5.1.1 The marking of the angular adjustment gas spring consists of the code, cylinder inner diameter, stroke, extension length, joint type and nominal force. The regulations are as follows: JKQ
one cylinder inner diameter
one angle adjustment gas spring code
extension length
nominal force
one joint type
piston rod end connection type
one cylinder end connection type
5.1.2 The marking of the lifting gas spring consists of the code, cylinder outer diameter, stroke, extension length, joint type and nominal force. The regulations are as follows: 611
5.2 Marking example
JB/T 8064.2-96
-Cylinder outer diameter
-Lifting gas spring code
Extension length
-Joint type
Nominal force
Piston rod end connection type
Cylinder end connection type
Example: The cylinder inner diameter of the angular adjustment gas spring is 24mm, the stroke is 60mm, the extension length is 260mm, the joint type is UM type, and the nominal force is 350N.
Marked as: JKQ24-60-260 (UM) 3506 Technical requirements
6.1 Gas springs shall comply with the requirements of this standard and be manufactured according to product drawings and technical documents approved by the prescribed procedures. 6.2 Dimensions and appearance quality
6.2.1 The piston rod diameter and piston rod stroke of the gas spring shall be selected in accordance with GB/T2348 and GB2349. When the piston rod diameter and piston rod stroke of the gas spring meet the above standards, it can be indicated in the technical documents: The piston rod diameter and stroke of this product meet the provisions of the national standards GB/T2348 and GB2349.
6.2.2 The dimensional tolerance of the extended length of the gas spring shall be manufactured according to the IT16 grade precision specified in GB1800. 6.2.3 The electroplating layer shall comply with the provisions of GB/T13913 and JB2864, and the main surface shall be smooth and free of defects such as bumps, scratches, peeling, bubbling, pinholes, tumors, stains, color difference, etc.
6.2.4 The chemical treatment layer shall comply with the provisions of JB2864, and the color shall be uniform, without red rust, obvious spots and attached sediments. 6.2.5 The quality of the paint coating shall comply with the provisions of JB/Z111. The paint layer shall be flat, the color shall be consistent, there shall be no obvious pitting, no serious sagging, and the bottom shall not be exposed.
6.3 Performance requirements
6.3.1 There shall be no jamming phenomenon when the gas spring is cycled, that is, the dynamic friction force shall not be greater than the maximum value in one cycle. The nominal force limit deviation and the maximum value of dynamic friction force shall comply with the provisions of Table 2. Table 2
Nominal force
201～400
401～800
801～1600
Nominal force limit deviation
Note: The force limit deviation can also be used asymmetrically according to the agreement between the supply and demand parties, and its tolerance value remains unchanged. Maximum value of dynamic friction force
The opening force, locking force and nominal force of the gas spring are interrelated. After the nominal force is determined, the opening force and locking force are determined by the agreement between the supply and demand parties according to the load conditions.
6.3.2 The elastic force ratio of the gas spring shall be determined by agreement between the supplier and the buyer according to the load conditions. 6.3.3 The starting force of the gas spring shall be less than 1.5F3. 6.3.4 The extension speed of the gas spring shall be between 100 and 200 mm/s. If there are special needs, it can be determined by agreement between the supplier and the buyer, 612
6.3.5 Sealing performance
JB/T8064.2--96
When the control valve of the gas spring is closed, the piston shall have good sealing to ensure that the piston rod can be locked in any position. 6.3.6 Corrosion resistance
The gas spring shall be able to withstand a 48h neutral salt spray test. After the test, there shall be no visible corrosion defects on the surface of the piston rod and the cylinder. 6.3.7 High and low temperature storage performance
The gas spring shall be able to withstand a high and low temperature storage test of -30℃ and 60℃ for 48h each. After the test, the nominal force attenuation shall not be greater than 5%. 6.3.8 Cycle life
The gas spring after the high and low temperature storage performance test should be able to withstand 30,000 cycle life tests. After the test, the nominal force attenuation should be less than 10%, and the dynamic friction force should comply with the provisions of Table 2. 6.3.9 Tensile strength
The gas spring is kept under the tensile force of 1.5 times the locking force for 5 minutes, and the gas spring force performance should remain unchanged; the gas spring is kept under the tensile force of 3 times the locking force for 5 minutes, and the gas spring is allowed to fail but shall not be dismembered. 7 Test method
7.1 Dimension and appearance inspection
7.1.1 The dimensions are inspected by special or general measuring tools with a graduation value less than or equal to 0.02mm. 7.1.2 The appearance quality is inspected by visual inspection or a 4x magnifying glass. The electroplating layer, chemical treatment and paint layer are inspected according to the relevant provisions of GB/T13913, JB2864 and JB/Z111 respectively. The results shall meet the requirements of 6.2.3 to 6.2.5. 7.2 Force performance test
7.2.1 Test conditions
The test is carried out at 20℃±2℃. Before the test, the gas spring should be kept in an extended state in an environment of 20℃±2℃. The piston rod should not be pressed. It should be placed for more than 2h. The measuring speed of the test machine is 200mm/min. The force measurement accuracy of the test machine is not less than 1%, and the displacement measurement accuracy is not less than 1%.
7.2.2 Test method
The piston rod of the gas spring is vertically installed on the test machine using the connectors at both ends. The opening force and starting force are recorded in the first cycle of the start-up. The extension force and compression force F1, F2, F3, F4 are recorded in the second cycle, and the nominal force, dynamic friction force and elastic force ratio of the gas spring are calculated from them. The rigidly locked gas spring should be locked in the extended state and its locking force should be tested. The measuring speed of the test machine is 2mm/min. The axial compression force required to make the piston rod produce a displacement of 1mm is the locking force value. Before testing the elastically locked gas spring, it should be cycled three times under simulated working conditions and then locked at the midpoint of the stroke. The measuring speed of the testing machine is 8mm/min. The axial compression force required to move the piston rod by 4mm is the locking force. 7.3 Extension speed test
7.3.1 Test conditions
The test is carried out in an environment of 20℃±2℃. Before testing, the gas spring should be placed in an environment of 20℃±2℃ for more than 2h. The graduation value of the timer is less than or equal to 1/100s.
7.3.2 Test method
During the test, the piston rod of the gas spring should be fixed on the testing machine relative to the base. In the initial state, the gas spring is locked in the minimum position, and then the valve push rod is quickly pressed to make the cylinder stretch freely. The stretching time and stretching distance S are measured, and the stretching speed (average speed) can be calculated according to formula (1).
Where: -
Stretching speed,
Stroke:
-Stretching time.
7.4 Sealing performance test
(1)
JB/T 8064.2-96
Lock the gas spring in the compressed state and measure the extension length of the piston rod. The extension length should remain unchanged within 24 hours. 7.5 Corrosion resistance test
The corrosion resistance test of the gas spring shall be carried out in accordance with the provisions of GB/T1771 and GB6458. The test results shall comply with the provisions of 6.3.6. 7.6 High and low temperature storage performance test
Put the gas spring in a low temperature test box at 30℃±2°C for 48 hours. After taking it out, place it in a high temperature test box at 60℃±2℃ and keep it for 48 hours. After taking it out, place the gas spring at 20℃±2℃ for 4 hours. The measured nominal force attenuation shall comply with the provisions of 6.3.7. 7.7 Life test
The gas spring that has been tested for high and low temperature storage performance shall be tested for force characteristics according to 7.2, and then clamped on the testing machine. The testing machine operates the gas spring to cycle under simulated T conditions, and the frequency of the cycle is 10~16 times/min. During the entire test process, the temperature of the gas spring cylinder should not be greater than 50C. After each cycle of 10,000 times, the force performance shall be measured once according to the test method of 7.2. After 30,000 cycles, the measured results shall comply with the provisions of 6.3.5 and 6.3.8.
7.8 Tensile strength test
Fix the gas spring on the testing machine t. and load it at a speed of 2mm/min. Test according to the provisions of 6.3.9. 8 Inspection rules
8.1 Inspection classification
Product inspection is divided into type inspection and factory inspection. 8.2 Type inspection
Type inspection should be carried out in any of the following situations: a) Trial design and identification of new products or old products for transfer to factory production; b) After formal production, if there are major changes in structure, materials, and processes that may affect product performance; {) During formal production, regular inspections should be carried out after a certain amount of production has been accumulated; d) When the product is resumed after a long period of suspension; e) When there is a significant difference between the factory inspection results and the last type inspection; f) When the national quality supervision agency proposes a requirement for type inspection. 8.2.1 Defects
Gas springs that do not meet the technical requirements specified in the product technical standards, process documents, and drawings constitute defects. According to the severity of the defects, they are divided into:
A Defect item (fatal defect)
B Defect item (serious defect)
C Defect item (general defect)
See Table 3 for specific contents
A Defect item
High and low temperature storage performance
Cycle life
Tensile strength
8.2.2 Sampling method
8.2.2.1 Determination of inspection batch
B Defect item Gan
Mechanical characteristics
Sealing performance
C Defect item
Dimension and appearance quality
Neutral salt spray resistance
a) The inspection batch must be qualified gas spring products, and 500 gas springs are one inspection batch. If the number of products is greater than 500 pieces, the inspection personnel shall arbitrarily divide the inspection batches into 500 pieces, and then randomly determine the inspection batches as the inspection objects. b) If the number of products is less than 50 pieces, it is not appropriate to sample the inspection batch, and the inventory products shall be selected for sampling. 8.2.3 Sample selection
JB/T 8064.296
8.2.3.1 Non-destructive inspection items share one sample. If the number of products is greater than 280 pieces, according to the general inspection level 1, sample size code F, normal inspection one sampling plan specified in GB2828, 20 gas springs shall be selected; if the number of products is less than 280 pieces, according to the general inspection level I, sample size code E, normal inspection one sampling plan specified in GB2828, 13 gas springs shall be selected. 8.2.3.2 High and low temperature storage performance, cycle life, and tensile strength share a sample. In the same inspection batch, according to the special inspection level S-1 and sample size code B of the normal sampling plan specified in GB2828, 3 gas springs are selected. 8.2.4 Total number of samples
50≤N<280 pieces, the total number of samples is 16 pieces
280≤N≤500 pieces, the total number of samples is 23 pieces. 8.2.5 Qualified quality level (AQL)
The qualified quality level of A defect item and B defect item I is 4.0 respectively. The qualified quality level of C defect item is 6.5. 8.3 Factory inspection
All products must be inspected before leaving the factory. 8.3.1 Inspection items
The inspection shall be carried out according to Table 4, and the ambient temperature shall be 20℃±2℃. Table 1
Inspection items
Nominal force
Stretch length
Force characteristic curve
Stretch speed
Inspection category
8.3.2 Acceptable quality level (AQL)
Inspection method and requirements
Perform according to 7.2 on the testing machine; if it meets the requirements of Table 2, perform according to 7.1.2; if it meets the requirements of 6.2.3 to 6.2.5, perform according to 7.1.1; if it meets the requirements of 6.2.1 and 6.2.2, perform according to 7.2; if it meets the requirements of 6.3.1.6.3.2.6.3.3, perform according to 7.3; if it meets the requirements of 6.3.4
8.3.2.1 If there are unqualified items in the mandatory inspection items, the part shall be directly judged as unqualified; 8.3.2.2
The acceptable quality level (AQL) of the random inspection items shall be in accordance with the relevant provisions of the type inspection. 9 Marking, packaging, transportation, storage
9.1 Product marking
Each gas spring product should be marked with the following in an obvious position: a) Product name, model or mark:
b) Manufacturer name;
c) Production date or production batch number;
d) High-pressure products must not be disassembled at will;
e) Trademark:
f) Certificate of conformity.
9.2 Packing box marking
The following markings should be on the gas spring packaging box: a) Product name, model:
b) Manufacturer name and address;
c) The number of products in the box;
d) Overall dimensions and gross weight;
e) Date of sale;
f) Marking "anti-high temperature", "handle with care", etc. 9.3 Packaging
JB/T 8064.2-96
9.3.1 Each gas spring product shall be packed in a plastic bag, and there shall be flexible material between each gas spring in the packing box. 9.3.2 The gross weight of each box shall not be greater than 30kg.
The packing box shall be accompanied by a certificate of conformity stamped by the technical inspection department. 9.3.3
9.3.4 Transportation
Gas springs shall be protected from mechanical damage and rain and snow during transportation. 9.3.5 Storage
Gas spring products shall be stored in a dry and ventilated warehouse, free of acid, alkali or other corrosive gases. Under normal storage conditions, there shall be no rust on the coating, peeling of paint, etc. within 3 years, and the nominal force attenuation shall not be greater than 5%. 6165 Storage
Gas spring products should be stored in a dry, ventilated warehouse, with no acid, alkali or other corrosive gases around. Under normal storage conditions, there should be no rust on the coating, peeling of paint, etc. within 3 years, and the nominal force attenuation should not be greater than 5%.
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