A device and method for testing the radial stiffness of a multi-coil spring system

Abstract

This invention discloses a radial stiffness testing device and method for a multi-helical spring system, relating to the field of spring lateral stiffness testing. The device includes an upper pull plate and a horizontal plate. Symmetrically arranged spring seats are mounted on both sides of the upper pull plate. Spring limiting seats and spring mounting seats are respectively mounted on two opposite surfaces of the spring seats. A spring retainer is also installed between the spring limiting seats and the spring mounting seats, and a lower pull plate is mounted on the spring retainer. The extension ends of multiple lower pull plates are connected to the horizontal plate. This invention can achieve the testing of the overall radial stiffness value of a multi-helical spring system, ensuring the accuracy of the overall radial stiffness value of the system, thereby ensuring the overall precision and reliability of the system.

Description

Technical Field

[0001] This invention relates to the field of spring lateral stiffness testing, and more specifically, to a radial stiffness testing device and method for a multi-helix spring system. Background Technology

[0002] The radial deformation capacity of a spring refers to its ability to stretch or expand perpendicular to its axis. This capacity is widely used in mechanical transmissions and precision instruments. Helical springs, in particular, exhibit linear radial stiffness characteristics. While the radial stiffness of a helical spring is determined through theoretical calculations during design, the actual radial stiffness differs from the theoretical value. In applications requiring high force accuracy, theoretical calculations may not meet practical needs. Therefore, when using helical springs to achieve radial floating, if the system demands high force accuracy, the radial stiffness of the helical spring must be tested and verified.

[0003] Current methods for testing the stiffness of helical springs mainly focus on the axial stiffness, while the determination of radial stiffness relies on theoretical calculations, resulting in a lack of effective radial stiffness testing methods. However, theoretical calculations can only obtain the radial stiffness of a single helical spring system. For multi-helical spring systems, the cumulative error in radial stiffness calculations is large, posing a significant risk in high-precision systems engineering applications.

[0004] Therefore, there is an urgent need for a radial stiffness testing device and method for multi-helical spring systems, so as to realize the testing of the overall radial stiffness value of the multi-helical spring system, ensure the accuracy of the overall radial stiffness value of the system, and thus ensure the overall precision and reliability of the system. Summary of the Invention

[0005] The purpose of this invention is to provide a radial stiffness testing device and method for a multi-helical spring system, which can test the overall radial stiffness value of the multi-helical spring system, ensure the accuracy of the overall radial stiffness value of the system, and thus ensure the overall precision and reliability of the system.

[0006] To achieve the objective of this invention, the technical solution adopted is as follows: a radial stiffness testing device for a multi-helical spring system, comprising an upper pull plate and a horizontal plate, wherein spring seats are symmetrically arranged on both sides of the upper pull plate, and spring limiting seats and spring mounting seats are respectively installed on two opposite sides of the spring seats; a spring retainer is also installed between the spring limiting seat and the spring mounting seat, and a lower pull plate is also installed on the spring retainer, and the extension ends of the multiple lower pull plates are all connected to the horizontal plate.

[0007] Furthermore, the spring limiting seat, spring retainer, and spring mounting seat all have stepped shafts that are adapted to the inner diameter of the helical spring.

[0008] Furthermore, the spring mounting base also has a central shaft extending towards the spring limiting seat, the extended end of the central shaft being fixed to the spring limiting seat, and the inner diameter of the spring holder being greater than twice the diameter of the central shaft.

[0009] Furthermore, a collision sleeve is also fitted on the central shaft of the spring mounting base.

[0010] Furthermore, the collision sleeve is made of non-metallic material.

[0011] Furthermore, there are two pull plates, which are fixed back to back and attached together, and the spring seats are arranged symmetrically with respect to the contact surfaces of the two pull plates. The two symmetrically arranged spring seats are fixed together with the two pull plates respectively.

[0012] Furthermore, there are two spring holders between the spring limiting seat and the spring mounting seat. The two spring holders are arranged back to back, and the end of the pull-down plate away from the horizontal plate is sleeved on the central axis of the spring mounting seat. The inner diameter of the pull-down plate away from the horizontal plate is equal to the inner diameter of the spring holder.

[0013] Furthermore, the upper pull plate is engaged with the spring seat.

[0014] Furthermore, an upper pull rod is fixed to the upper pull plate, and a lower pull rod is fixed to the lower pull plate. The upper pull rod and the lower pull rod are on the same straight line, and the upper pull rod is located at the center of multiple spring seats.

[0015] A method for testing the radial stiffness of a multi-helical spring system, comprising the testing apparatus as described above, and further comprising the following steps:

[0016] Step 1: Install both ends of the helical spring between the spring limiting seat and the spring retainer, or / and between the spring retainer and the spring mounting seat;

[0017] Step 2: Mount the testing device onto the tensile clamp of the electronic universal testing machine;

[0018] Step 3: The servo motor of the electronic universal testing machine drives the tensile chuck and pulls the upper plate. Observe the tensile force data of the electronic universal testing machine until the force sensor on the electronic universal testing machine displays a value.

[0019] Step 4: Read the tensile force and displacement values ​​during the testing process of the electronic universal testing machine, and calculate the overall radial stiffness value of multiple helical springs based on the tensile force and displacement values.

[0020] Furthermore, the formula for calculating the overall radial stiffness value of multiple helical springs is as follows:

[0021]

[0022] in, Radial stiffness / Nm -1 , This represents the change in tensile force of the electronic universal testing machine. This refers to the displacement change of the electronic universal testing machine. This represents the final tensile force value of the electronic universal testing machine. This represents the initial tensile force value of the electronic universal testing machine. This represents the final displacement of the electronic universal testing machine. This is the initial displacement of the electronic universal testing machine.

[0023] The beneficial effects of this invention are:

[0024] This invention can measure the actual radial stiffness value of a multi-coil spring as a whole, achieve high-precision radial force control, ensure that the radial force of the multi-spring system achieves the predetermined design conditions, and thus ensure the operating accuracy of the entire system. At the same time, this invention can adjust the number of coil springs according to actual needs during actual testing, making it more adaptable.

[0025] The testing device provided by this invention has a simple and reliable structure and low cost. It can simultaneously test the radial stiffness of evenly spaced helical springs (two springs per group, or ≥2 groups are acceptable). Furthermore, the testing device is compatible with electronic universal testing machines, allowing data acquisition and analysis to be completed on standard electronic universal testing machines with reliable results.

[0026] This invention is applied to the radial stiffness of a multi-coil spring combination in a system that uses radial deformation of helical springs to achieve a floating function. In scenarios where helical springs are needed to achieve floating or other scenarios that require the radial deformation capability of helical springs, this method can make the radial stiffness of the entire system measurable and controllable, ensuring high-precision and high-reliability operation of the system and achieving precise control of radial force and radial displacement. Attached Figure Description

[0027] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0028] Figure 1 This is a structural diagram of a radial stiffness testing device for a multi-helix spring system;

[0029] Figure 2 This is a side view of the radial stiffness testing device for a multi-helix spring system;

[0030] Figure 3 This is the front view of the radial stiffness testing device for a multi-helix spring system;

[0031] Figure 4 This is a cross-sectional schematic diagram of a radial stiffness testing device for a multi-helix spring system;

[0032] Figure 5 This is an installation diagram of the spring limit seat, spring retainer, and spring mounting seat.

[0033] The attached diagram shows the markings and corresponding component names:

[0034] 1. Top pull rod, 2. Bottom pull rod, 3. Top pull plate, 4. Bottom pull plate, 5. Horizontal plate;

[0035] 4-1. Groove;

[0036] 6-1. Spring seat; 6-2. Helical spring; 6-3. Spring limit seat; 6-4. Spring retainer; 6-5. Spring mounting seat; 6-7. Collision sleeve.

[0037] 6-5-1, Step axis; 6-5-2, Central axis. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] like Figures 1 to 5As shown, the present invention provides a radial stiffness testing device for a multi-helix spring system, comprising an upper pull plate 3 and a horizontal plate 5. Both the upper pull plate 3 and the horizontal plate 5 are rectangular plates, with the upper pull plate 3 arranged vertically and the horizontal plate 5 arranged horizontally, located below the upper pull plate 3. Spring seats 6-1 are installed on both sides of the upper pull plate 3. The spring seats 6-1 on the same side of the upper pull plate 3 are symmetrically arranged on the upper pull plate 3, and the spring seats 6-1 on both sides of the upper pull plate 3 are symmetrically arranged based on the upper pull plate 3. The spring seats 6-1 are U-shaped, with their openings facing the horizontal plate 5. A spring limiting seat 6-3 and a spring mounting seat 6-5 are respectively fixed to the two opposite sides of the spring seat 6-1 by bolts. The spring limiting seat 6-3 and the spring mounting seat 6-5 are mutually oriented. The center axis 6-5-2 of the spring limiting seat 6-3 and the center axis 6-5-2 of the spring mounting seat 6-5 are on the same straight line. A spring retainer 6-4 is also installed between the spring limiting seat 6-3 and the spring mounting seat 6-5. The center axis 6-5-2 of the spring retainer 6-4 is on the same straight line as the center axis 6-5-2 of the spring mounting seat 6-5. In use, the two ends of the helical spring 6-2 are respectively installed on the spring limiting seat 6-3 and the spring retainer 6-4, or the two ends of the helical spring 6-2 are respectively installed on the spring retainer 6-4 and the spring mounting seat 6-5. When the helical spring 6-2 is not pulled, the center axis of the helical spring 6-2 is on the same straight line as the center axis 6-5-2 of the spring retainer 6-4.

[0041] Meanwhile, a pull-down plate 4 is also installed on the spring holder 6-4. The pull-down plate 4 extends towards the horizontal plate 5, and the extension ends of multiple pull-down plates 4 are fixed together on the horizontal plate 5. When the pull-up plate 3 is pulled, the pull-up plate 3 drives the spring seat 6-1, the spring limit seat 6-3, and the spring mounting seat 6-5 to move synchronously, so that the spring holder 6-4, the spring limit seat 6-3, and the spring mounting seat 6-5 generate relative movement, thereby causing the helical spring 6-2 installed on the spring holder 6-4 to undergo radial deformation, which facilitates the testing of the radial stiffness value of the helical spring 6-2.

[0042] In this invention, to facilitate the subsequent installation of the helical spring 6-2, the diameters of the spring limiting seat 6-3, the spring retainer 6-4, and the spring mounting seat 6-5 are larger than the diameter of the helical spring 6-2. A stepped shaft 6-5-1 is provided on the opposing surfaces of the spring limiting seat 6-3 and the spring retainer 6-4, and on the opposing surfaces of the spring retainer 6-4 and the spring mounting seat 6-5. The diameter of the stepped shaft 6-5-1 is adapted to the inner diameter of the helical spring 6-2. This allows the helical spring 6-2 to be directly fitted onto the stepped shaft 6-5-1 on the spring limiting seat 6-3, the spring retainer 6-4, or the spring mounting seat 6-5, and then pressed against them. This not only makes the installation and disassembly of the helical spring 6-2 more convenient but also prevents radial displacement of the spring after installation.

[0043] In this invention, the two ends of the helical spring 6-2 are sleeved on the stepped shaft 6-5-1 on the spring limiting seat 6-3, the spring retainer 6-4, or the spring mounting seat 6-5. Even if one end of the helical spring 6-2 is pressed to the limit position, the other end of the helical spring 6-2 will not fall off, thus ensuring the safety of the testing process.

[0044] To ensure the installation accuracy of the helical spring 6-2, the spring mounting base 6-5 also has a central shaft 6-5-2 extending to the spring limiting seat 6-3. The central shaft 6-5-2 and the spring mounting base 6-5 are an integral structure, and the extended end of the central shaft 6-5-2 is fixed to the spring limiting seat 6-3 by screws. To prevent the central shaft 6-5-2 from affecting the testing of the helical spring 6-2, the diameter of the central shaft 6-5-2 is less than one-third of the inner diameter of the helical spring 6-2. To ensure the relative movement between the spring holder 6-4, the spring limiting seat 6-3, and the spring mounting base 6-5, the inner diameter of the spring holder 6-4 is more than twice the central diameter.

[0045] In this invention, to facilitate the installation of the helical spring 6-2, the spring mounting base 6-5 with the central shaft 6-5-2 is preferentially fixed on the side of the spring seat 6-1 near the upper pull plate 3. This allows the helical spring 6-2 to be installed by simply removing the spring limiting seat 6-3, the spring retainer 6-4, and the lower pull plate 4, without needing to disassemble the spring seat 6-1 or the spring mounting base 6-5, making the installation of the helical spring 6-2 more convenient.

[0046] Of course, in this invention, without considering the ease of installing the helical spring 6-2, when the spring mounting seat 6-5 is fixed on the side of the spring seat 6-1 near the upper pull plate 3, the central shaft 6-5-2 can also be integrated with the spring limiting seat 6-3. In this case, the extended end of the central shaft 6-5-2 is fixed to the spring mounting seat 6-5 by screws.

[0047] To prevent the helical spring 6-2 from colliding with the central shaft 6-5-2 during testing, a collision sleeve 6-7 is fitted onto the central shaft 6-5-2 of the spring mounting base 6-5. The collision sleeve 6-7 is made of non-metallic material, which not only prevents the helical spring 6-2 from colliding with the central shaft 6-5-2 during testing, but also ensures the safety of the helical spring 6-2 during the testing process.

[0048] In this invention, there are two pull-up plates 3, which are fitted together and fixed together with bolts to form a whole. There are multiple spring seats 6-1, which are arranged symmetrically with the mating surfaces of the two pull-up plates 3 as the reference surface. Specifically, during installation, the spring seats 6-1 are first fixed to the pull-up plates 3 with screws or bolts. After the spring seats 6-1 are installed, the two pull-up plates 3 are then fixed with bolts to prevent the screws or bolts fixing the spring seats 6-1 from loosening, thus making the installation of the spring seats 6-1 more stable.

[0049] To facilitate the connection between the pull-down plate 4 and the spring holder 6-4, two spring holders 6-4 are provided between the spring limit seat 6-3 and the spring mounting seat 6-5. The two spring holders 6-4 are arranged back to back, and their opposing surfaces are both planes. The stepped shaft 6-5-1 is located on the corresponding surface of the spring holder 6-4, the spring limit seat 6-3, and the spring mounting seat 6-5. At the same time, a through hole is provided at the end of the pull-down plate 4 that is connected to the spring holder 6-4. The diameter of the through hole is not less than the inner diameter of the spring holder 6-4. The pull-down plate 4 is fitted onto the central shaft 6-5-2 on the spring mounting seat 6-5 at the end connected to the spring holder 6-4 and is arranged between the two spring holders 6-4. At this time, the two spring holders 6-4 are in contact with the two sides of the pull-down plate 4, and the two spring holders 6-4 and the pull-down plate 4 are fixed together with bolts, so that the pull-down plate 4 and the spring holder 6-4 are fixed together.

[0050] To prevent relative displacement between the spring holder 6-4 and the pull-down plate 4, a groove 4-1 can be made on the side of the pull-down plate 4 near the spring holder 6-4. The diameter of the groove 4-1 matches the diameter of the spring holder 6-4. During installation, one spring holder 6-4 is installed in the groove 4-1, and the other spring holder 6-4 is in contact with the surface of the pull-down plate 4. This allows the pull-down plate 4 to be fixed with bolts while the groove 4-1 and the spring holder 6-4 are engaged to limit displacement between them, thus improving the installation accuracy of the spring holder 6-4 and the pull-down plate 4.

[0051] In this invention, to ensure that the force of the upper pull plate 3 or the lower pull plate 4 is applied to the coil spring 6-2 when it is pulled, the upper pull plate 3 is engaged with the spring seat 6-1. That is, the spring seat 6-1 has a slot, and the upper pull plate 3 has a locking block that engages with the slot; or the spring seat 6-1 has a protruding locking block, and the upper pull plate 3 has a slot that engages with the locking block. This ensures both the installation accuracy of the spring seat 6-1 and the precise application of force to the coil spring 6-2, thus guaranteeing the accuracy of the test.

[0052] To facilitate the installation of the testing device during the testing process, an upper pull rod 1 is fixed to the upper pull plate 3 by a pin, and a lower pull rod 2 is fixed to the lower pull plate 4 by a pin. The central axis 6-5-2 of the lower pull rod 2 is on the same straight line as the central axis 6-5-2 of the upper pull rod 1. The upper pull rod 1 is located at the center of multiple spring seats 6-1. This prevents the testing device from tilting due to uneven force distribution of the helical springs 6-2 during the testing process, and makes the force on the multiple helical springs 6-2 more uniform during the test, thus ensuring the accuracy of the test.

[0053] Based on the above-mentioned testing device, the present invention also provides a method for testing the radial stiffness of a multi-helical spring system, comprising the following steps:

[0054] Step 1: Divide the coil springs 6-2 into two groups, with two coil springs 6-2 in each group. Loosen the installation of the spring limiting seat 6-3, the connection between the spring limiting seat 6-3 and the central shaft 6-5-2 on the spring mounting seat 6-5, and the connection between the pull-down plate 4 and the horizontal plate 5. Remove the spring limiting seat 6-3 from the spring seat 6-1 and separate the pull-down plate 4 from the horizontal plate 5. Remove the commonly fixed spring holder 6-4 and pull-down plate 4 from the collision sleeve 6-7. Next, place one of the coil springs 6-2 from the same group onto the collision sleeve 6-7, and place one end of it onto the platform of the spring mounting seat 6-5. On the stepped shaft 6-5-1, the commonly fixed spring holder 6-4 and pull-down plate 4 are fitted onto the collision sleeve 6-7, and the other end of the helical spring 6-2 is fitted onto the stepped shaft 6-5-1 of the limiting sleeve. Next, another helical spring 6-2 in the same group is fitted onto the collision sleeve 6-7, with one end fitted onto the stepped shaft 6-5-1 of the other spring holder 6-4, and the helical spring 6-2 is compressed so that the other end of the helical spring 6-2 is fitted onto the stepped shaft 6-5-1 of the spring limiting seat 6-3, fixing the spring limiting seat 6-3 to the spring seat 6-1 and the spring mounting seat 6-5. Multiple sets of helical springs 6-2 are installed in this way, and the multiple sets of helical springs 6-2 are arranged symmetrically with the contact surface of the two pull-up plates 3 as the reference plane.

[0055] Step 2: After assembling the helical spring 6-2, clamp the upper pull rod 1 and the lower pull rod 2 onto the two tensile clamps of the electronic universal testing machine using pins, and ensure the stability of the connection between the upper pull rod 1, the lower pull rod 2 and the two tensile clamps of the electronic universal testing machine.

[0056] Step 3: The servo motor of the electronic universal testing machine drives the tensile fixture connected to the upper pull rod 1. While the upper pull rod 1 is being pulled, it drives the upper pull plate 3, spring seat 6-1, spring limit seat 6-3, and spring mounting seat 6-5 to move synchronously, so that the spring under test gradually produces radial deformation. During this process, the tensile force data of the electronic universal testing machine is observed until the force sensor on the electronic universal testing machine shows a value.

[0057] Step 4: Read the tensile force and displacement values ​​during the testing process of the electronic universal testing machine. These tensile force and displacement values ​​correspond to the radial force and radial displacement values ​​of the multiple coil springs 6-2 as a whole, respectively. Calculate the radial stiffness value of the multiple coil springs 6-2 as a whole based on these values. The formula for calculating the radial stiffness value of the multiple coil springs 6-2 as a whole is as follows:

[0058]

[0059] in, Radial stiffness / Nm -1 , This represents the change in tensile force of the electronic universal testing machine. This refers to the displacement change of the electronic universal testing machine. This represents the final tensile force value of the electronic universal testing machine. This represents the initial tensile force value of the electronic universal testing machine. This represents the final displacement of the electronic universal testing machine. This is the initial displacement of the electronic universal testing machine.

[0060] In this invention, the number of helical springs 6-2 can be selected according to actual conditions, but it must be ensured that the number of groups of helical springs 6-2 is even, and that multiple helical springs 6-2 are symmetrically arranged on the testing device with the contact surfaces of the two upper pull plates 3 as the reference; and that two helical springs 6-2 form a group, with the two helical springs 6-2 in the same group installed between the spring limiting seat 6-3 and the spring retainer 6-4, and between the spring retainer 6-4 and the spring mounting seat 6-5. That is, the testing device of this invention is for a system composed of multiple groups of helical springs 6-2, and tests the radial stiffness of the entire system, not for a single helical spring 6-2.

[0061] Meanwhile, in this invention, the helical spring 6-2 already has a certain amount of compression during installation, that is, the helical spring 6-2 has been pre-compressed during testing, and its radial stiffness will change after pre-compression, so as to better simulate the state of the helical spring 6-2 in actual use, and make the final test result closer to the overall radial stiffness of multiple helical springs 6-2 in use.

[0062] This invention tests a system composed of multiple helical springs 6-2. Compared to a single helical spring 6-2, a system composed of multiple helical springs 6-2 may exhibit different radial displacements during radial force application, resulting in varying radial forces and displacements for each spring 6-2. Furthermore, due to manufacturing errors, the radial stiffness of each spring 6-2 may differ. In a system composed of multiple helical springs 6-2, the focus is on the overall radial stiffness of the system. Measuring and summing the radial stiffness of individual springs 6-2 would amplify manufacturing errors. Therefore, the testing device and method proposed in this invention can accurately measure the radial stiffness of the entire spring system, without focusing on the radial stiffness of individual springs. Even with manufacturing errors or varying forces on each spring, the testing accuracy of the overall spring system can be guaranteed.

[0063] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A multi-coil spring system radial stiffness testing device characterized by, The assembly includes an upper pull plate (3) and a horizontal plate (5). Symmetrically arranged spring seats (6-1) are mounted on both sides of the upper pull plate (3). A spring limiting seat (6-3) and a spring mounting seat (6-5) are respectively mounted on two opposite surfaces of the spring seats (6-1). The spring mounting seat (6-5) also has a central shaft (6-5-2) extending towards the spring limiting seat (6-3), and the extended end of the central shaft (6-5-2) is fixed to the spring limiting seat (6-3). A spring retainer is also installed between the spring limiting seat (6-3) and the spring mounting seat (6-5). (6-4), and a pull-down plate (4) is also installed on the spring holder (6-4), and the extension ends of multiple pull-down plates (4) are connected to the horizontal plate (5); there are two spring holders (6-4) between the spring limiting seat (6-3) and the spring mounting seat (6-5), the two spring holders (6-4) are arranged back to back, and the end of the pull-down plate (4) away from the horizontal plate (5) is sleeved on the central axis (6-5-2) of the spring mounting seat (6-5), and the inner diameter of the pull-down plate (4) away from the horizontal plate (5) is equal to the inner diameter of the spring holder (6-4).

2. The radial stiffness testing device for a multi-helix spring system according to claim 1, characterized in that, The spring limiting seat (6-3), spring retainer (6-4), and spring mounting seat (6-5) all have stepped shafts (6-5-1) that are adapted to the inner diameter of the helical spring.

3. The radial stiffness testing device for a multi-helix spring system according to claim 1, characterized in that, The inner diameter of the spring holder (6-4) is more than twice the diameter of the central shaft (6-5-2).

4. The radial stiffness testing device for a multi-helical spring system according to claim 3, characterized in that, The spring mounting base (6-5) is also fitted with a collision sleeve (6-7) on its central shaft (6-5-2), and the collision sleeve (6-7) is made of non-metallic material.

5. The radial stiffness testing device for a multi-helix spring system according to claim 1, characterized in that, There are two upper pull plates (3), which are fixed back to back and attached together. The spring seats (6-1) are arranged symmetrically with respect to the contact surfaces of the two upper pull plates (3). The two symmetrically arranged spring seats (6-1) are fixed together with the two pull plates respectively.

6. The radial stiffness testing device for a multi-helix spring system according to claim 1, characterized in that, The upper pull plate (3) is engaged with the spring seat (6-1).

7. The radial stiffness testing device for a multi-helix spring system according to claim 1, characterized in that, The upper pull plate (3) is also fixed with an upper pull rod (1), and the lower pull plate (4) is also fixed with a lower pull rod (2). The upper pull rod (1) and the lower pull rod (2) are on the same straight line, and the upper pull rod (1) is located at the center of multiple spring seats (6-1).

8. A method for testing the radial stiffness of a multi-helical spring system, characterized in that, Including the testing apparatus as described in any one of claims 1 to 7, the method further includes the following steps: Step 1: Install both ends of the helical spring between the spring limiting seat (6-3) and the spring retainer (6-4) or / and between the spring retainer (6-4) and the spring mounting seat (6-5); Step 2: Mount the testing device onto the tensile clamp of the electronic universal testing machine; Step 3: The servo motor of the electronic universal testing machine drives the tensile chuck and pulls the upper pull plate (3), and observes the tensile data of the electronic universal testing machine until the force sensor on the electronic universal testing machine shows a value; Step 4: Read the tensile force and displacement values ​​during the testing process of the electronic universal testing machine, and calculate the overall radial stiffness value of multiple helical springs (6-2) based on the tensile force and displacement values.

9. The radial stiffness testing method for a multi-helical spring system according to claim 8, characterized in that, The formula for calculating the overall radial stiffness of multiple helical springs (6-2) is as follows: in, Radial stiffness / Nm -1 , This represents the change in tensile force of the electronic universal testing machine. This refers to the displacement change of the electronic universal testing machine. This represents the final tensile force value of the electronic universal testing machine. This represents the initial tensile force value of the electronic universal testing machine. This represents the final displacement of the electronic universal testing machine. This is the initial displacement of the electronic universal testing machine.

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