Tag: National Standard Setter of gas spring in China
Test Methods of Compression Gas Springs
7. Test Methods
7.1 Dimensions and Appearance
- 7.1.1 Dimensions shall be inspected using special or universal measuring tools with a scale division value not greater than 0.5 mm.
- 7.1.2 Appearance quality shall be inspected by visual inspection.
7.2 Force Characteristics
- 7.2.1 Test Conditions
The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the gas spring shall always be in the extended state, and the piston rod shall not be pressed. The sample shall be placed in an environment of 20°C ± 2°C for
7.2 Force Characteristics
- 7.2.1 Test Conditions
The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the gas spring shall always be in the extended state, and the piston rod shall not be pressed. The sample shall be placed in an environment of 20°C ± 2°C for more than 2 hours. The test measurement speed is 400 mm/min, and the force measurement accuracy is not lower than 1%.
Note: For variable – damping gas springs and pressure – damping gas springs, the test speed is 100 mm/min – 300 mm/min. - 7.2.2 Test Methods
The test methods for force characteristics are divided into dynamic tests and static tests. The dynamic test method should be used as much as possible.- 7.2.2.1 Dynamic Test
Install the piston rod of the gas spring vertically upward on the testing machine. In the first cycle of starting the machine, record the starting force. In the second cycle, record the extension force and compression force , , , at the force – measuring point , and calculate the nominal force, dynamic friction force and force ratio, and draw the force – displacement curve. At the same time, observe whether there is any jamming or obvious jitter of the gas spring piston rod.
- 7.2.2.2 Static Test
Install the piston rod of the gas spring vertically upward on the testing machine. In the first cycle of starting the machine, record the starting force. In the second cycle, record the extension force and compression force , , , at the force – measuring point , and calculate the nominal force and force ratio, and draw the force – displacement curve. The static test stays at the force – measuring point for 3 s. At the same time, observe whether there is any jamming or obvious jitter of the gas spring piston rod.
- 7.2.2.1 Dynamic Test
7.3 Extension Speed
- 7.3.1 Test Conditions
The test shall be carried out in an environment of 20°C ± 2°C. Before the test, the sample shall be placed in an environment of 20°C ± 2°C for more than 2 hours. The scale division value of the timer is not greater than 1/100 s. - 7.3.2 Test Methods
Install the piston rod of the gas spring vertically downward on the testing machine. Start the testing machine, press the piston rod into the specified stroke, and then remove the external force to allow the piston rod to extend freely. Measure the extension time and the extended stroke , and calculate the extension speed (average speed) according to the following formula:
Where:
– Extension speed, in millimeters per second (mm/s);
– Stroke, in millimeters (mm);
– Extension time, in seconds (s).
7.4 High and Low Temperature Resistance Performance
Place the gas spring in a high – temperature test chamber at 110°C ± 5°C for 1 hour, then take it out and place it in a normal – temperature environment for 2 hours. Then place the gas spring in an environment of – 40°C ± 2°C, and then place it in an environment of 80°C ± 5°C for 4 hours. The above is a high – low temperature cycle test. Test the force characteristics of the gas spring after the high – low temperature test according to 7.2, and calculate the attenuation of the nominal force .
7.5 Cycle Life
- 7.5.1 Normal Temperature Cycle Life
Install the piston rod of the gas spring after the high – low temperature test downward on a testing machine equipped with an oil – collecting device, and conduct a cycle life test at a frequency of 4 times/min – 6 times/min (for variable – damping gas springs and pressure – damping gas springs, it is 3 times/min – 5 times/min). During the test, the piston rod should extend freely. After 25,000 cycles, test the force characteristics according to 7.2, calculate the attenuation of the nominal force , and then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g. - 7.5.2 Environmental Cycle Life
Install the piston rod of the gas spring downward on a high – low temperature dynamic cycle testing machine equipped with an oil – collecting device. Lower the test environment temperature to – 40°C, and conduct a cycle life test at a frequency of 2 times/min – 4 times/min for 1,000 cycles. Take it out and test the force characteristics according to 7.2, and calculate the attenuation of the nominal force . Then install the gas spring on the testing machine, adjust the test environment temperature to 80°C ± 5°C, and conduct a cycle life test at a frequency of 4 times/min – 6 times/min (for variable – damping gas springs and pressure – damping gas springs, it is 2 times/min – 5 times/min) for 1,000 cycles. Take it out and test the force characteristics according to 7.2, and calculate the attenuation of the nominal force . Then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g. After the high – low temperature dynamic cycle test, the gas spring is subjected to a normal – temperature cycle life test of 18,000 times. Test the force characteristics according to 7.2, calculate the attenuation of the nominal force , and then weigh the amount of oil brought out on an electronic scale with an accuracy of not less than 0.01 g.
7.6 Tensile Resistance Performance
Fix the extended gas spring on the testing machine, and load it at a speed of 1 mm/min – 2 mm/min according to the specified value in Table 3, and keep it for 3 minutes. After unloading, test the force characteristics according to 7.2 or observe.
7.7 Corrosion Resistance Performance
The corrosion resistance test of the gas spring shall be carried out in accordance with the provisions of GB/T 1771 or GB/T 10125.
Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).
Technical Requirements of compression gas sprin
6. Technical Requirements
Products shall meet the requirements of this standard and be manufactured in accordance with the product drawings and technical documents confirmed by both the supplier and the demander. The materials and coatings selected for manufacturing products shall comply with the safety and environmental protection regulations of the application area.
6.1 Dimensions and Appearance Quality
- 6.1.1 The ratio of D₂/D₁ shall not be less than 1. The diameter and stroke of the gas spring piston rod shall be selected in accordance with GB/T 2348 and GB/T 2349. Special requirements shall be agreed upon by the supplier and the demander.
- 6.1.2 The tolerance of the extended length of the gas spring shall comply with the IT16 accuracy level specified in GB/T 1800.1.
- 6.1.3 The coating on the piston rod of the gas spring shall be uniform, and the surface shall be smooth, without defects such as scars, blisters, peeling, pitting, pinholes, and nodules.
- 6.1.4 The coatings on other exposed parts except the piston rod shall be uniform, without defects such as red rust, peeling, blisters, roughness, and missing plating (except for process holes and holes smaller than 1 mm).
- 6.1.5 The paint coating on the gas spring cylinder shall comply with the provisions of QC/T 484. The paint coating shall be uniform, without exposed substrate, obvious pitting, or serious sagging.
6.2 Force Characteristics
For gas springs with a specified force greater than 100 N, the force value shall be determined in integer multiples of 50 N. There shall be no jamming or obvious jitter during the compression and extension processes of the gas spring.
- 6.2.1 Specified Force F× and Dynamic Friction Force F,
The limit deviation of the specified force value and the dynamic friction force shall comply with the provisions of Table 2. In case of special needs, it shall be agreed upon by the supplier and the demander.
| Specified Force Value (N) | Limit Deviation of Specified Force Value (N) | Maximum Dynamic Friction Force F, (N) |
|—|—|—|
| ≤100 | ±5 | 25 |
| 101 – 200 | +20 – 10 | 30 |
| 201 – 400 | +30 – 15 | 40 |
| 401 – 600 | +40 – 20 | 60 |
| 601 – 800 | +50 – 25 | 80 |
| 801 – 1000 | +60 – 30 | 100 |
| 1001 – 1200 | +70 – 35 | 130 |
| >1200 | +80 – 40 | 150 | - 6.2.2 Start – up Force F₀
The start – up force of the gas spring shall be less than 1.5F₃. - 6.2.3 Force Ratio
The force ratio of the gas spring shall be agreed upon by the supplier and the demander according to the usage situation. - 6.2.4 Liquid Damper Part
The length of the liquid damper part of the gas spring shall be agreed upon by the supplier and the demander according to the load situation.
6.3 Extension Speed
The extension speed of the gas spring shall be between 50 mm/s and 350 mm/s. In case of special needs, it shall be agreed upon by the supplier and the demander.
6.4 High and Low Temperature Resistance Performance
After the gas spring is stored at a high temperature of 110°C and then undergoes two high – low temperature cycle tests at – 40°C and 80°C, it shall not fail, and the attenuation of its nominal force F. shall not be greater than 5%.
6.5 Cycle Life
- 6.5.1 Normal Temperature Cycle Life
After the gas spring undergoes high – low temperature tests, it shall undergo a cycle life test of 25,000 times (when the stroke ≤ 200 mm, the actual stroke shall be used; when the stroke > 200 mm, a stroke of 200 mm shall be used). After the test, the total attenuation of its nominal force F. shall not be greater than 13%, the dynamic friction force shall comply with the provisions of Table 2, and the amount of oil brought out shall be less than 0.5 g. - 6.5.2 Environmental Cycle Life
For gas springs used in harsh environments, after 1,000 high – low temperature dynamic cycle life tests at – 40°C and 1,000 tests at 80°C, the attenuation of their nominal force F. shall not be greater than 5%. After the gas springs undergo high – low temperature dynamic cycle life tests, they shall then undergo a normal temperature cycle life test of 18,000 times (when the stroke ≤ 200 mm, the actual stroke shall be used; when the stroke > 200 mm, a stroke of 200 mm shall be used). After the test, the total attenuation of their nominal force F. shall not be greater than 13%, the dynamic friction force shall comply with the provisions of Table 2, and the amount of oil brought out shall be less than 0.5 g.
Note 1: 6.5.1 and 6.5.2 are not required simultaneously.
Note 2: When 6.5.2 is required, 6.4 shall not be required.
6.6 Tensile Resistance Performance
The tensile resistance performance of gas spring products shall comply with the provisions of Table 3.
| Minimum Cross – Sectional Dimension of the Tensile Part (mm) | Tensile Force (N) | Tensile Force (N) |
| The force characteristics of the gas spring remain unchanged | The gas spring is allowed to fail, but shall not break or disintegrate | |
| φ5 | 1000 | 2000 |
| φ6 | 1500 | 3000 |
| φ8 | 3000 | 6000 |
| φ10 | 4000 | 8000 |
| φ12 | 5000 | 10000 |
| Note 1: For non – metallic connectors, it shall be agreed upon by the supplier and the demander. Note 2: For the minimum cross – sectional area of the tensile part larger than φ12, it shall be agreed upon by the supplier and the demander. | Note 1: For non – metallic connectors, it shall be agreed upon by the supplier and the demander. Note 2: For the minimum cross – sectional area of the tensile part larger than φ12, it shall be agreed upon by the supplier and the demander. | Note 1: For non – metallic connectors, it shall be agreed upon by the supplier and the demander. Note 2: For the minimum cross – sectional area of the tensile part larger than φ12, it shall be agreed upon by the supplier and the demander. |
6.7 Corrosion Resistance Performance
- 6.7.1 After a 96 – hour neutral salt spray test, the gas spring shall have no blisters, peeling, or corrosion defects; the threads at the rod end and tube end and the hole openings shall have no blisters or peeling.
- 6.7.2 After a 48 – hour neutral salt spray test, the hard – chrome – plated piston rod shall have no blisters, peeling, or corrosion defects on its rod body; the threads at the rod end and the hole openings shall have no blisters or peeling.
- 6.7.3 The corrosion resistance performance of other exposed parts shall comply with the provisions of the corresponding coatings in QC/T 625. In case of special needs, it shall be agreed upon by the supplier and the demander.
Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).
Connectors and Marking of gas spring
4. Types
4.1 Shape and Force – Displacement Curve
The shape and force – displacement curve of the gas spring are shown in Figure 1.
4.2 Types and Codes of Gas Spring Connectors
The types and codes of gas spring connectors are shown in Figure 2. Other connection types shall be agreed upon by the supplier and the demander.
| Code | Connection Type |
| 0 | Single Piece |
| U | Double – Ear |
| L | Single – Ear |
| B | Universal Ball Head |
5. Marking
5.1 Marking Method
The marking of the gas spring consists of the code, piston rod diameter (which may not be marked), cylinder outer diameter (which may not be marked), stroke, extended length, and specified force value, as specified below: [Marking diagram description]
5.2 Marking Examples
- Example 1: For a compression gas spring with a piston rod diameter of 10 mm, a cylinder outer diameter of 22 mm, a stroke of 200 mm, an extended length of 500 mm, and a minimum extension force F₁ (lifting force) of 650 N.
Marking: YQ 10/22 – 200 – 500 F₁650 or YQ 200 – 500 F₁650 - Example 2: For a compression gas spring with a piston rod diameter of 8 mm, a cylinder outer diameter of 18 mm, a stroke of 150 mm, an extended length of 400 mm, and a nominal force F. of 350 N.
Marking: YQ 8/18 – 150 – 400 F.350 or YQ 150 – 400 F.350
Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).
Definition & Symbols of Compression Gas Springs
3. Terms, Definitions, Symbols and Explanations
The terms, definitions, symbols and explanations established in GB/T 1805 and Table 1 apply to this standard.
| Term | Definition or Explanation | Symbol | Unit |
| Gas Spring | An elastic element composed of a sealed cylinder, a piston that can slide in the cylinder, and a piston rod assembly, using nitrogen or other inert gases as the energy – storage medium | ||
| Compression Gas Spring | A gas spring in which the piston rod is in a freely extended state without external force and can withstand pressure | ||
| Piston Rod Diameter | The diameter of the piston rod of the gas spring | d | mm |
| Cylinder Inner Diameter | The inner diameter of the gas spring cylinder | D₁ | mm |
| Cylinder Outer Diameter | The outer diameter of the gas spring cylinder | D₂ | mm |
| Stroke | The axial displacement of the piston rod from the fully extended state to the minimum compressed size | S | mm |
| Extended Length | The effective length of the gas spring in the fully extended state | L | mm |
| Start – up Force | The initial force required to press the piston rod after the gas spring has been in the extended state for a certain period | F₀ | N |
| One Cycle | The piston rod is compressed and extended once each according to the specified stroke | ||
| Specified Force | The force marked on the drawings and products confirmed by both the supplier and the demander (F, Fa, F₃, …) | Fx | N |
| Minimum Extension Force | The force measured at the specified force – measuring point C at the starting point of the working stroke during the extension process | F₁ | N |
| Maximum Extension Force | The force measured at the specified force – measuring point C at the end point of the working stroke during the extension process | F₂ | N |
| Minimum Compression Force | The force measured at the specified force – measuring point C at the starting point of the working stroke during the compression process | F₃ | N |
| Maximum Compression Force | The force measured at the specified force – measuring point C at the end point of the working stroke during the compression process | F₄ | N |
| Nominal Force a | F.=(F₁ + F₃)/2. Nominal force a is one of the indicators of the comprehensive characteristics of the gas spring | F. | N |
| Nominal Force b | F₆=(F₂ + F₄)/2. Nominal force b is generally used for calculating the force ratio | F₆ | N |
| Dynamic Friction Force | F,=(F₃ – F₁)/2 | F, | N |
| Extension Speed | The average speed at which the piston rod freely extends from the end of the specified stroke to the initial position | v | mm/s |
| Gas Damper Part | The area where the piston movement is affected by gas damping during the extension process of the piston rod | mm | |
| Liquid Damper Part | The area where the piston movement is affected by liquid damping during the extension process of the piston rod | mm | |
| Measuring Point | The point for collecting force values during dynamic or static testing. When S≤80 mm, C = 5 mm; when S>80 mm, C = 10 mm | C | mm |
| Force Ratio | α = F₆/F. | α |
Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).
Technical Specification for Compression Gas Springs – national standard
Compression gas spring technical specification
Issued on December 23, 2010 – Implemented on October 1, 2011
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China and the Standardization Administration of China
Foreword
This standard is proposed by China Machinery Industry Federation.
This standard is under the jurisdiction of the National Spring Standardization Technical Committee.
Technical Specification for Compression Gas Springs
1. Scope
This standard specifies the terms and definitions, markings, technical requirements, test methods, inspection rules, as well as requirements for identification, packaging, transportation, and storage of compression gas springs (hereinafter referred to as “gas springs”).
This standard is applicable to gas springs using nitrogen or other inert gases as energy – storage working media.
2. Normative References
The provisions of the following documents are incorporated into this standard by reference. For dated references, subsequent amendments (excluding errata) or revised editions do not apply to this standard. However, parties reaching agreements based on this standard are encouraged to explore the possibility of using the latest editions of these documents. For undated references, their latest editions apply to this standard.
- GB/T 1771 Paints and Varnishes – Determination of Resistance to Neutral Salt Spray (GB/T 1771—2007, ISO 7253:1996, IDT)
- GB/T 1800.1 Geometrical Product Specifications (GPS) – Limits and Fits – Part 1: Basics of Tolerances, Deviations and Fits (GB/T 1800.1—2009, ISO 286 – 1:1988, MOD)
- GB/T 1805 Spring Terminology
- GB/T 2348 Hydraulic and Pneumatic Systems and Components – Cylinder Bore Diameters and Piston Rod Outer Diameters (GB/T 2348—1993, neq ISO 3320:1987)
- GB/T 2349 Hydraulic and Pneumatic Systems and Components – Piston Stroke Series of Cylinders
- GB/T 2828.1 Sampling Procedures for Inspection by Attributes – Part 1: Sampling Plans for Lot – by – Lot Inspection Retrieved by Acceptable Quality Limit (AQL) (GB/T 2828.1—2003, ISO 2859 – 1:1999, IDT)
- GB/T 2829 Sampling Procedures and Tables for Periodic Inspection by Attributes (Applicable to the Inspection of Process Stability)
- GB/T 10125 Corrosion Tests in Artificial Atmospheres – Salt Spray Tests (GB/T 10125—1997, eqv ISO 9227:1990)
- QC/T 484 Automobile Paint Coatings
- QC/T 625 Coatings and Chemical Treatment Layers for Automobiles
Technical Specification for Compression Gas Springs (English version of national strandard, initiated by LeiYan Gas Springs), proposed and prepared by SAC/TC 235 (National Technical Committee 235 on Spring of Standardization Administration of China).