Spiral compression spring

Abstract

The invention discloses a spiral compression spring which comprises supporting rings at the two ends and a spring body located between the two supporting rings, the spring body and the supporting rings are sequentially, directionally and spirally wound to form a cylindrical shape, the rings at the two ends of the spiral compression spring are tightened and ground flat or flattened and then tightened and ground flat, and gaps are formed between the rings of the spring body. A contact line compensation ring is additionally arranged on the supporting ring; the contact line compensation ring and the supporting ring are integrally formed, and the contact line compensation ring extends by a certain length from the contact point of the supporting ring and the spring body to the tail tip direction along the spiral line of the supporting ring. According to the method, the contact line of the cylindrical spiral compression spring can be independently compensated, the length of the contact line meeting the standard requirement can be obtained without loading or loading a very small axial load, the properties such as the total number of turns, the number of effective turns, the free height, the compression height and the reserved safety stroke are not changed, the stability and the bearing capacity are improved, and the service life of the spiral compression spring is prolonged. The service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of springs, and in particular to a helical compression spring. Background Art

[0002] According to the standard "BS EN 13298:2003 Railway Applications - Suspension Components - Steel Coil Springs", the inspection and testing of Class A coil springs requires testing whether the contact line length meets the requirements; it stipulates that the contact line length must be at least 0.33 of the average spring diameter D, and gives a method for measuring the contact line length. According to the standard "TB / T2211-2018 Compression Steel Coil Springs for Locomotives and Rolling Stocks", during type tests, both Class A and Class B coil springs need to be tested to see if the contact line length meets the requirements. During factory inspection, Class A coil springs need to be tested to see if the contact line length meets the requirements. The requirements for the contact line length are specified: when the spring is subjected to a static load FV, the contact line length of the upper and lower end rings of the spring with the end rings in the form of tight and flattened should be more than 0.33 times the median diameter D, and should be at least 20mm; for springs with the end rings in the form of sharpened, tight and flattened, when the steel rod diameter d≥20mm, the contact line length should be more than 20mm, and when the steel rod diameter d<20mm, the contact line length should be greater than or equal to the steel rod diameter d. In summary, the importance of the contact line length in the spring has a great impact on the spring performance.

[0003] The contact line length refers to the length of the line where the spring end coil contacts the connected part, which directly affects the spring's load-bearing capacity, stability, and service life. When the contact line length is short, the spring is prone to deformation when subjected to force, resulting in a decrease in load-bearing capacity, stress concentration, and increased risk of fatigue failure. On the contrary, a longer contact line length can provide a larger contact area, thereby enhancing the spring's load-bearing capacity, making it more stable when subjected to external force, and can also disperse stress and reduce stress concentration, thereby extending the spring's service life.

[0004] In actual application, most springs break on the effective coil near the end. For example, the article "Analysis of Fatigue Failure Causes of Cylindrical Helical Springs for Urban Rail Trains" states that the fracture position of the primary spring of the locomotive during use is the first working coil on the upper end of the inner spring, and the fracture surface is at a 45° angle to the spring axis. The cause of the fracture is that the end of the spring support coil and the effective coil of the spring are constantly squeezed and collided during the operation of the locomotive, resulting in fatigue fracture at the contact point due to stress concentration. This shows that the spring support coil and the effective coil are not in line contact but in local point contact during operation. It can be seen from this that the length of the spring contact line is important in the working process of the spring.

[0005] In order to ensure that the spring contact line length meets the standard requirements, there are some conventional solutions. For example, the angle between the spring support ring and the effective ring is reduced to extend the spring contact line length, but the number of effective rings will be reduced, resulting in a larger spring stiffness; the number of support rings is increased to extend the spring contact line length, but the free height will be increased, affecting the spring stiffness. The method used in the article "Analysis of Fatigue Failure Causes of Cylindrical Helical Springs for Urban Rail Trains" is: grinding the spring to eliminate surface defects at the end of the support ring to extend the spring contact line length, but it will be time-consuming and labor-intensive; using a new type of rolling forging die with arc grooves on both the upper and lower rolling forging surfaces to grind the spring end, so that the upper and lower surfaces are arc surfaces to ensure the contact line length after winding into a spring, but it will reduce the number of effective rings and affect the stiffness.

[0006] The prior art CN 102537163 A "A design method for the total number of coils of a spring" discloses a spiral spring with a contact line compensation coil and a method for calculating the total number of coils. The extension direction of the contact line length in the article is opposite to that of the present invention. The total number of coils of the spring in the article = the number of coils converted from the effective coil + the length of the end coil ground + the number of coils converted from the contact line length. It can be seen that the number of coils converted from the contact line length causes a change in the total number of coils of the spring, thereby affecting the free height and the compressed height of the spring. The contact line compensation coil of the present invention will not cause a change in the total number of coils of the spring, so compared with the spring with the same parameters that does not adopt the present invention, it will not change the stiffness, free height, and compressed height of the spring.

[0007] It can be seen from this that it is necessary to invent a cylindrical helical compression spring that can ensure that the contact line length meets the standard requirements and that the performance of the spring remains unchanged. Summary of the invention

[0008] The purpose of the present invention is to provide a helical compression spring to address the deficiencies of the prior art, which can not only ensure that the contact line length meets the standard requirements, but also ensure that the performance of the spring remains unchanged.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A helical compression spring comprises support rings at both ends and a spring body located between the two support rings. The spring body and the support rings are spirally wound in a directional manner in sequence to form a cylindrical shape. The two end rings of the helical compression spring are either tightly put together and ground flat or flattened and then tightened and ground flat. There is a gap between the rings of the spring body. A contact line compensation ring is added to the support ring; the contact line compensation ring and the support ring are integrally formed, and the contact line compensation ring extends a certain length from the contact point between the support ring and the spring body along the spiral line of the support ring toward the tail tip.

[0011] Preferably, the contact line compensation ring does not change the total number of turns nt of the helical compression spring.

[0012] Preferably, the contact line compensation ring does not change the number n of effective turns of the helical compression spring.

[0013] Preferably, the contact line compensation ring does not change the free height and the compressed height of the helical compression spring.

[0014] Preferably, both end coils of the helical compression spring are tightened and ground flat or flattened and then tightened and ground flat.

[0015] Preferably, the gaps between the turns of the spring body are equal.

[0016] Preferably, the length of the contact wire compensation ring is the length of the arc corresponding to the spring steel rod rotating 38° to 90° along the middle diameter of the helical compression spring.

[0017] Preferably, there is no requirement for the thickness of the end of the helical compression spring, and the arc corresponding to the spring steel rod rotating 90° along the helical compression spring's median diameter corresponds to the minimum median diameter of the helical compression spring:

[0018]

[0019] Where: D represents the minimum mean diameter of the helical compression spring.

[0020] Preferably, for the requirements of the end thickness of the helical compression spring, the minimum bar size required for the contact line length (the length of the line where the end coil of the helical compression spring contacts the connected part) is:

[0021]

[0022] Where: d represents the minimum bar size required for the contact line length.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention has a simple structure and an ingenious design. By extending a contact line compensation circle from the contact point between the support ring and the spring body along the spiral line of the support ring toward the tail tip, the contact line length is independently compensated, so that the contact form between the support ring and the effective ring is changed from local point contact to line contact; and the contact line length that meets the standard requirements can be obtained without loading or loading a very small axial load;

[0025] (2) The total number of turns, effective number of turns, free height, compressed height and reserved safety stroke of the cylindrical helical compression spring obtained by the present invention remain unchanged, the stability and load-bearing capacity of the cylindrical helical compression spring are improved, fatigue fracture caused by stress concentration is avoided, and the service life of the cylindrical helical compression spring is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is the front view of a common helical compression spring;

[0027] Figure 2 This is an end view of a common helical compression spring;

[0028] Figure 3 It is a structural schematic diagram of the present invention;

[0029] Figure 4 It is a front view of the present invention;

[0030] Figure 5 is an end view of the present invention;

[0031] Figure 6 This is a diagram of the contact line length measurement result of Example 1;

[0032] Figure 7 This is a contact line length measurement result diagram of Comparative Example 1;

[0033] In the figure: 1-spring body; 2-contact line compensation ring; 3-support ring; 4-contact point. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings:

[0035] like Figure 1-2 As shown, the common helical compression spring comprises a spring body 1 and a support ring 3. The spring body 1 and the support ring 3 are spirally wound in a directional manner in sequence to form a cylindrical shape. The end rings of the spring are in the form of being tightly ground or tightly ground and then flattened. There is a gap between the rings of the spring body 1. There is a local point contact between the end of the support ring 3 and the spring body 1, and the contact point is the starting point of the spring body 1. The end of the spring is ground approximately at 3 / 4 of a circle.

[0036] like Figure 3-5 As shown, a helical compression spring of the present invention comprises support rings 3 at both ends and a spring body 1 located between the two support rings 3. The spring body 1 and the support ring 3 are spirally wound in a directional manner in sequence to form a cylindrical shape. The two end rings of the helical compression spring are in the form of being tightly connected and ground flat or being tightly connected and ground flat after being flattened. There is a gap between the rings of the spring body 1, and a contact line compensation ring 2 is added to the support ring 3; wherein the contact line compensation ring 2 and the support ring 3 are integrally formed, and the contact line compensation ring 2 extends a certain length from the contact point 4 between the support ring 3 and the spring body 1 along the spiral line of the support ring 3 toward the tail tip.

[0037] The contact line compensation ring 2 of the present invention does not change the total number of coils n of the helical compression spring. t The number of, the number of effective circles n, the free height and the pressed height.

[0038] The two end coils of the helical compression spring of the present invention are both tightened and ground flat or tightened and ground flat after being flattened. The gaps between the coils of the spring body 1 are equal. The end coils of the helical compression spring of the present invention are ground between 3 / 4 and 1 coil, and the length of the contact line compensation coil 2 is less than or equal to 1 / 4 coil. The helical compression spring of the present invention does not need to be loaded or loaded with a very small axial load to obtain a contact line length that meets the standard requirements.

[0039] The length of the contact line compensation ring 2 in the present invention is the length of the arc corresponding to the spring steel rod rotating 38° to 90° along the spring middle diameter.

[0040] According to the standard "BS EN 13298:2003 Railway Applications - Suspension Components - Steel Helical Springs", the contact wire length is at least 0.33 of the average spring diameter D. Therefore, the minimum length of the contact wire compensation ring 2 can be converted into the angle corresponding to the arc length:

[0041]

[0042] Therefore, after the middle diameter of the helical compression spring is determined, the length of the contact line compensation ring 2 is at least the length of the arc corresponding to the rotation 38 of the spring steel rod along the middle diameter of the spring.

[0043] According to the standards of "BS EN 13298:2003 Railway Applications - Suspension Components - Steel Helical Springs" and "GB / T23934-2015 Technical Conditions for Hot-coiled Cylindrical Helical Compression Springs", the thickness of the end tip should be between 3 mm and 1 / 4 of the nominal cross-sectional size of the spring steel bar, the end face grinding length is about 3 / 4 turns, and the end face thickness after 3 / 4 turns of grinding is about 1 / 4 of the bar size. Therefore, the minimum bar size that can meet the contact line length requirements of the present invention can be obtained:

[0044]

[0045] It can be obtained that: d≥20.8mm.

[0046] It can be seen from this that if there is a requirement for the end thickness, the minimum rod size that can meet the contact wire length requirement of the present invention is 20.8mm, and the upper limit of the length of the contact wire compensation ring 2 is determined according to the specific rod size; if there is no requirement for the end thickness, the rod size that can meet the contact wire length requirement of the present invention does not need to be limited, and the length of the contact wire compensation ring 2 is the length of the arc corresponding to the spring steel rod rotating 38° to 90° along the middle diameter of the spring.

[0047] According to the standard "TB / T 2211-2018 Compression Steel Coil Spring for Locomotives and Rolling Stocks", different requirements for contact line length are required for different end ring forms.

[0048] 1) For springs with tightly ground end rings, the contact line length of the upper and lower end rings should be at least 0.33 times the median diameter D, and should be at least 20 mm. Based on the above European standards, the requirement of a contact line length of at least 20 mm is added.

[0049] For requirements on end thickness: From the above, we can know that the minimum bar size is 20.8mm. According to the standard "GB / T23934-2015 Technical Conditions for Hot-rolled Cylindrical Helical Compression Springs", the winding ratio ω of the spring is 3 to 12. Taking the winding ratio of the spring as 3, the minimum mean diameter of the spring is D=ωd=62.4mm, and the corresponding contact line length is L=0.33D=20.592mm>20mm, which meets the standard requirements.

[0050] For the case where there is no requirement for the end thickness: From the above, it can be seen that the length of the contact line compensation ring 2 is the length of the arc corresponding to the spring steel rod rotating 38° to 90° along the spring middle diameter, where the arc corresponding to the spring steel rod rotating 90° along the spring middle diameter corresponds to the minimum middle diameter of the spring:

[0051]

[0052] It can be obtained that: D ≥ 25.5 mm. The length of the contact line compensation ring 2 can meet the requirement of the contact line length.

[0053] 2) The end ring is a spring that is flattened, tightened and ground. When the steel rod diameter d ≥ 20 mm, the contact line length should be more than 20 mm; when the steel rod diameter d < 20 mm, the contact line length should be greater than or equal to the steel rod diameter d.

[0054] (1) When the diameter of the steel bar d ≥ 20 mm, the contact line length should be more than 20 mm.

[0055] ① For requirements on end thickness:

[0056]

[0057] Arranged:

[0058]

[0059] Using d to represent ω, we get:

[0060]

[0061] According to the standard "GB / T 23934-2015 Technical Conditions for Hot-rolled Cylindrical Helical Compression Springs", the coiling ratio ω of the spring is 3 to 12, and the bar size d is 8 mm to 60 mm. It can be obtained that 20 mm ≤ d ≤ 60 mm

[0062] It can be concluded that for requirements on the end thickness, the conditions required for the length of the contact line compensation ring 2 to meet the contact line length requirements are:

[0063]

[0064] ② For those with no requirement on end thickness: take the winding ratio as 3, the minimum center diameter is D=3d=60mm, and the length of 1 / 4 circle is L=πD / 4≈47.2mm>20mm. It can be concluded that for those with no requirement on end thickness, the length of the contact line compensation circle 2 can meet the contact line length requirement.

[0065] (2) When the diameter of the steel rod d is less than 20 mm, the length of the contact line should be greater than or equal to the diameter of the steel rod d.

[0066] ① For requirements on end thickness:

[0067]

[0068] Arranged:

[0069] (d-12)ωπ-4d≥0

[0070] Using d to represent ω, we get:

[0071]

[0072] According to the standard "GB / T 23934-2015 Technical Conditions for Hot-rolled Cylindrical Helical Compression Springs", the coiling ratio ω of the spring is 3 to 12, and the bar size d is 8 mm to 60 mm. It can be obtained that: 13.5 mm ≤ d < 20 mm.

[0073] In summary, it can be concluded that for requirements on the end thickness, the conditions required for the length of the contact line compensation ring 2 to meet the contact line length requirements are:

[0074]

[0075] ② For those without requirements on end thickness:

[0076]

[0077] We can get: ω≥4 / π

[0078] Since 4 / π<3, it can be obtained that when there is no requirement for the end thickness, the length of the contact line compensation ring 2 can meet the contact line length requirement.

[0079] Example 1

[0080] According to the structure of the present invention, a contact line compensation design is performed on a cylindrical helical compression spring, the end ring is in the form of being tightly closed and ground flat, and the manufactured spring is placed on an electro-hydraulic servo test bench for axial stiffness testing.

[0081] Test conditions: GL-40T electro-hydraulic servo test bench, manual loading mode, spring ends kept parallel and coaxial.

[0082] Test process: When not loaded, measure the contact line length, then gradually apply the load from 0kN to the axial load required for the axial stiffness test, and keep the load within the range of ±1%, and measure the contact line length and spring axial stiffness.

[0083] It can be seen from the test in Example 1 that when not loaded, the measured contact line length of the cylindrical helical compression spring is relatively long and meets the length specified by the standard. The contact line length measurement results are as follows: Figure 6 The axial stiffness of the cylindrical helical compression spring did not change during the test, proving that the cylindrical helical compression spring using this patented technology can ensure that the contact line length meets the standard requirements without affecting the performance.

[0084] Comparative Example 1

[0085] The test conditions and test process are the same as those of Example 1, except that the axial stiffness and contact line length test are performed using a cylindrical helical compression spring without a contact line compensation structure.

[0086] From the test of comparative example 1, it can be obtained that when not loaded, the contact line length of the cylindrical helical compression spring measured is 0, and the contact line length of the cylindrical helical compression spring measured after the load is stabilized is as follows: Figure 7 As shown in the figure, the shorter contact line length still does not meet the standard requirements, and the effective number of turns of the cylindrical helical compression spring decreases. The axial stiffness of the spring shows nonlinear changes during the test and gradually increases with the loading process. It can be determined that the change in the length of the contact line causes the change in the effective turn, which in turn causes the change in the axial stiffness.

[0087] It can be seen from the test results of Example 1 and Comparative Example 1 that the cylindrical helical compression spring using the structure of the present patent can ensure that the contact line length meets the standard requirements during use, can solve the fatigue fracture problem caused by the contact line length not meeting the standards, and the stiffness and free height and other properties of the cylindrical helical compression spring using the structure of the present patent do not change.

[0088] Example 2

[0089] According to the structure of the present invention, the contact line compensation design is performed on the cylindrical helical compression spring, the end ring is flattened and then tightly ground, and the manufactured spring is placed on an electro-hydraulic servo test bench for fatigue life testing.

[0090] Test conditions: GL-40T electro-hydraulic servo test bench, automatic loading mode, the spring ends remain parallel and coaxial, and the two ends of the spring are in flat contact.

[0091] Test process: The spring is cyclically loaded until 2×10 6 The fatigue life of the spring is measured by the number of infinite fatigue cycles or fracture.

[0092] According to the test in Example 2, under the design conditions, after 2×10 6 The spring did not fail or break after the second cycle.

[0093] Comparative Example 2

[0094] The test conditions and test process are the same as those of Example 2, except that the fatigue life test is performed using a cylindrical helical compression spring without a contact line compensation design.

[0095] From the test of comparative example 2, it can be found that the test is carried out to the 5.10213×10 5 The spring failed and broke in the first cycle, failing to reach the expected infinite number of fatigue cycles.

[0096] It can be seen from the test results of Example 2 and Comparative Example 2 that the cylindrical helical compression spring using the structure of the present patent can effectively extend the fatigue life of the spring.

[0097] Example 3

[0098] According to the structure of the present invention, a contact line compensation design is performed on a cylindrical helical compression spring, and the end ring is in the form of being tightly ground and flat. After the rated load is applied to the designed spring using a finite element simulation calculation method, the stress distribution at the contact line position is checked using a stress cloud map. By comparison, the stress at the contact line position is relatively dispersed, and the difference in stress between the contact line position and the surrounding positions is not large.

[0099] Comparative Example 3

[0100] The finite element simulation method was used to apply the rated load to the cylindrical helical compression spring with the same parameters but without contact line compensation design, and the stress distribution at the contact line position was checked using the stress cloud map. By comparison, the stress at the contact line position was more concentrated, and the difference was 1.5 times compared with the stress at the surrounding positions.

[0101] It can be seen from the simulation calculation results of Example 3 and Comparative Example 3 that the use of the cylindrical helical compression spring of the present invention can effectively alleviate the stress concentration phenomenon at the contact line position and can effectively avoid the fatigue fracture problem caused by stress concentration.

[0102] The other processes of the present invention can adopt existing technologies.

[0103] The best embodiments of the present invention have been described, and any further development of the present invention made by a person skilled in the art shall fall within the protection scope of the present invention.

Claims

1. A helical compression spring, characterized in that: The invention comprises support rings (3) at two ends and a spring body (1) located between the two support rings (3); the spring body (1) and the support ring (3) are spirally wound in a directional manner in sequence to form a cylindrical shape; the two end rings of the spiral compression spring are in the form of being tightly connected and ground flat or being tightly connected and ground flat after being flattened; there is a gap between the rings of the spring body (1); a contact line compensation ring (2) is added to the support ring (3); the contact line compensation ring (2) and the support ring (3) are integrally formed; the contact line compensation ring (2) starts from the contact point (4) between the support ring (3) and the spring body (1) and extends a certain length along the spiral line of the support ring (3) towards the tail tip.

2. The helical compression spring according to claim 1, characterized in that: The contact line compensation ring (2) does not change the total number of turns n of the helical compression spring t The number of 3. The helical compression spring according to claim 1, characterized in that: The contact line compensation ring (2) does not change the number n of effective turns of the helical compression spring.

4. The helical compression spring according to claim 1, characterized in that: The contact line compensation ring (2) does not change the free height and the compressed height of the helical compression spring.

5. The helical compression spring according to claim 1, characterized in that: The two end coils of the helical compression spring are either tightened and ground flat or tightened and ground flat after being flattened.

6. The helical compression spring according to claim 1, characterized in that: The gaps between the circles of the spring body (1) are equal.

7. The helical compression spring according to claim 1, characterized in that: The length of the contact wire compensation ring (2) is the length of the arc corresponding to the spring steel rod rotating 38° to 90° along the middle diameter of the helical compression spring.

8. The helical compression spring according to claim 7, characterized in that: There is no requirement for the thickness of the end of the helical compression spring. The arc corresponding to the spring steel rod rotating 90° along the helical compression spring's median diameter corresponds to the minimum median diameter of the helical compression spring: Where: D represents the minimum mean diameter of the helical compression spring.

9. The helical compression spring according to claim 7, characterized in that: For the requirements of the end thickness of the helical compression spring, the minimum bar size required for the contact line length (the length of the line where the end coil of the helical compression spring contacts the connected part) is: Where: d represents the minimum bar size required for the contact line length.

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