A high-frequency dynamic stiffness testing machine for railway fasteners

Abstract

The present invention relates to a high-frequency dynamic stiffness testing machine for railway fasteners, which includes a dynamic excitation system (1), a spring isolation system (3), a test-piece fastener fixing tooling (4), and a dynamic acquisition system (5). It also includes a static preloading system (2) that provides a preloading static force for the test-piece fastener system. The dynamic excitation system (1) provides a dynamic excitation force of 0 - 2000 Hz for the test-piece fastener system, and the dynamic acquisition system (5) acquires the preloading static force and vibration quantity values received by the test-piece fastener system. Compared with the prior art, the testing machine of the present invention can conduct high-frequency tests on the vertical and horizontal dynamic stiffness of railway fasteners under static preloading. The dynamic test frequency range can reach 0 - 2000 Hz. The testing machine integrates multiple professional systems, has a clear structural design hierarchy, high reliability, and strong feasibility.

Description

Technical Field

[0001] The present invention relates to the fields of mechanical engineering and rail transit, and provides a high-frequency dynamic stiffness test machine for railway fasteners. Background Art

[0002] In the field of rail transit, the fastener system is the most important component for connecting the rail and the sleeper. Its function is to fix the rail on the sleeper, maintain the gauge and prevent the longitudinal and lateral movement of the rail relative to the sleeper. The common fasteners for urban rail transit are designed for vibration reduction. The elastic pad of the fastener system is a two-layer design. As the operation time of the line increases, the elastic pad ages under the conditions of long-term damp and dark or exposure on elevated lines, and the stiffness of the fastener system increases. At the same time, with the continuous increase of the urban population, in order to further improve the transportation capacity, the subway company has increased the departure interval and running speed to varying degrees. At the same time, due to the change of the stiffness of the fastener system, the environmental protection pressure of urban rail transit has been further increased.

[0003] The commonly used high-speed railway fasteners in China are W300, WJ-8, WJ-7, SFC fasteners, etc. The designs are all in the structural form with an under-rail pad and an under-plate pad. Due to the characteristics of high-speed railway trains, such as large axle loads, high speeds, and high transport capacity densities, and the open-air use environment of high-speed railway fasteners, the aging rate of the elastic layer rubber is relatively high, resulting in an increase in the fastener stiffness, continuous aggravation of wheel-rail wear, and increasingly serious vibration and noise pollution along the railway line.

[0004] For the research on the stiffness of railway fasteners, domestic and foreign manufacturers mainly refer to the series of standards of BS EN13146-9:2009 and TB / T3395-2015 for the stiffness test of single-piece pads and assembled fastener systems. However, the requirements for the dynamic stiffness test of railway fasteners in both standards are low-frequency, basically in the range of 3 - 10 Hz.

[0005] For a single-piece elastic pad:

[0006] kN / mm

[0007] For the dynamic stiffness of the assembled fastener system:

[0008] kN / mm

[0009] However, according to the research results on the mechanism of vibration and noise of existing subways or high-speed rails and the damage of track components, the excitation frequency or resonance damage frequency generated after railway wheel-rail wear is generally above 400 Hz, and even exceeds 2000 Hz. There is no written report at home and abroad on the change law and trend of the fastener stiffness under the action of this excitation frequency of the track system. The exploration and research on the change law of the fastener stiffness under the high-frequency excitation characteristics of the wheel-rail have great reference significance for the research on the mechanism and control of wheel-rail noise and the damage of track system components.

[0010] The international standard ISO10846-5 proposes a set of test calculation methods for elastic elements using the excitation point measurement method. With the reduction of the stiffness of urban rail transit fasteners, the method in the standard has certain limitations. Because as the frequency range of the measured component increases, the contribution of the equivalent vibration mass inertia stiffness ω 2 m 1 to the measured dynamic stiffness k 11 of the excitation point also increases. At the same time, due to the low stiffness characteristics of the measured elastic unit, the equivalent support stiffness k i of the test system is no longer negligible, and only a set of test simulation devices is proposed, with low implementability.

[0011] An elastic unit dynamic stiffness measurement method and device in the existing patent ZL201710069046.2 corrects the elastic unit dynamic stiffness calculation method for the excitation point measurement method in ISO 10846-5. Therefore, according to the formula k 21 =k 11 +ω 2 m 1 - k i the corrected dynamic stiffness k 21 of the elastic unit is calculated. At the same time, the concept of the active excitation system method is extended for the test device in ISO 10846-5. Although the device and method improve the test accuracy to a certain extent and increase the test frequency to 400Hz, the excitation frequency above 400Hz of the elastic element cannot be tested. Moreover, this patent mainly corrects the method in ISO 10846-5, so only the recognition accuracy of the excitation frequency is considered. However, the installation and working environment of railway track fasteners are complex. In addition to the dynamic excitation caused by the passing of trains, there are also the influences of different axle loads of different vehicles. At the same time, the elastic components of the track structure are prone to characteristic changes caused by the coupling effects of multiple environments such as environmental temperature and humidity. The above existing devices cannot achieve all-round testing of fasteners and obtain the coupling characteristics of the high-frequency dynamics of fasteners, with low implementability. Summary of the Invention

[0012] The purpose of the present invention is to overcome the defects of the above existing technologies and provide a high-frequency dynamic stiffness test machine for railway fasteners that can perform vertical and horizontal dynamic stiffness high-frequency tests on railway fasteners, and the dynamic test frequency range can reach 0-2000Hz.

[0013] The object of the present invention can be achieved by the following technical solutions: A high-frequency dynamic stiffness test machine for railway fasteners, comprising a dynamic excitation system, a spring isolation system, a test-piece fastener fixing tooling, and a dynamic acquisition system, characterized in that it further comprises a static preloading system for providing a preloading static force to the test-piece fastener system. The dynamic excitation system provides a dynamic excitation force of 0 - 3000N to the test-piece fastener system, and the dynamic acquisition system acquires the preloading static force and vibration quantity values received by the test-piece fastener system.

[0014] When the test machine works, the static preloading system first loads to the rated static force value, the dynamic excitation system will perform dynamic excitation according to a certain dynamic excitation force value and amplitude, and the arranged test system starts to collect relevant dynamic parameters. This test machine can perform high-frequency tests on the vertical and horizontal dynamic stiffness of railway fasteners, and the dynamic test frequency range can reach 0 - 2000Hz.

[0015] The static preloading system includes a support base, a lower platform, a loading upper platform, an upper platform locking device, and a guiding column. The support base is placed under the lower platform, the test-piece fastener fixing tooling is installed on the lower platform, the loading upper platform is movably arranged up and down on the guiding column and is locked by the upper platform locking device, and the spring isolation system is installed under the loading upper platform;

[0016] When the loading upper platform contacts the spring isolation system along the guiding column and reaches the preload set force value, the upper platform locking device starts to work and clamps the loading upper platform, making the static preloading force value of the test machine adjustable, with an adjustment range of 0 - 150kN.

[0017] When the loading upper platform contacts the spring isolation system along the guiding column and reaches the preload set force value, the upper platform locking device clamps the loading upper platform through the servo valve hydraulic system and starts to work, and the static preloading force value of the test machine is adjustable, with an adjustment range of 0 - 150kN.

[0018] According to different requirements for railway fastener tests, the placement method and direction of the exciter can be the following two schemes:

[0019] The first one: The exciter system is vertically placed. By setting an exciter fixing seat on the loading upper platform of the static preloading system, the main excitation rod will perform vertical high-frequency excitation on the railway fastener.

[0020] The second one: The exciter system is horizontally placed. By horizontally setting an exciter fixing seat on the lower platform of the static preloading system, the main excitation rod will perform horizontal high-frequency excitation on the railway fastener.

[0021] Specifically: The dynamic excitation system includes a main excitation rod, an exciter, an exciter fixing seat, and a signal control and amplification system. The exciter is installed on the exciter fixing seat. By adjusting the position and direction of the exciter fixing seat, the main excitation rod provides lateral or vertical dynamic excitation to the fastener system under test.

[0022] Further, one end of the main excitation rod is connected to the exciter, and the other end passes through the static preloading system and then inserts into the spring isolation system to provide vertical dynamic excitation to the fastener system under test;

[0023] Alternatively, the main excitation rod laterally pushes the spring isolation system from the side, thereby providing lateral dynamic excitation to the fastener system under test.

[0024] For the exciter, by setting static preloading four guide columns and a four-guide-column stable holder, the adjustable range of the excitation force of the main excitation rod is 0 - 3000N. At the same time, in cooperation with the stiffness of the spring isolation system and the fixing device, the excitation frequency of the exciter for the fastener under test can reach 0 - 2000Hz.

[0025] The spring isolation system includes a spring lower bearing plate, a spring, and an upper positioning plate. The upper end of the spring is fixed to the bottom of the loading upper platform through the upper positioning plate, and the lower end is fixed to the spring lower bearing plate. The spring lower bearing plate contacts the fastener system under test.

[0026] The fastener fixture under test includes a fastener fixing bottom plate and a force measuring instrument;

[0027] The fastener system under test includes a fastener sleeper and the fastener under test. The fastener sleeper is fixed on the fastener fixing bottom plate, and a force measuring instrument is arranged under the fastener sleeper. The fastener under test fixes the rail on the fastener sleeper. The structure of the fastener sleeper can be suitable for existing high-speed rail W300, WJ-7, WJ-8, SFC and ordinary fasteners and vibration damping fastener systems used in subways.

[0028] The testing machine further includes a temperature control box, and the fastener fixture under test and the fastener system under test are placed in the temperature control box.

[0029] The dynamic acquisition system acquires the preloading static force and vibration values received by the fastener system under test, including acceleration signals, force signals, velocity signals, and displacement signals. The dynamic acquisition system is a combination of a non-contact laser displacement sensor, a force sensor, an amplifier, and a data acquisition system.

[0030] Further, by adjusting the temperature control box added, the fastener system under test can obtain transverse and vertical dynamic stiffness and dynamic damping parameters under different frequencies, different preloading pressures, and temperature gradients.

[0031] Further, the fixture is designed to achieve the maximum strength as much as possible and reduce the weight of the excited system.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The present invention designs a high-frequency dynamic stiffness test machine for railway fasteners. Due to the setting of the four-guide-column and four-guide-column stable holding frame structure of the static preloading system, and at the same time setting the static preloading spring isolation system and keeping it fixed, the dynamic excitation frequency of the test machine can reach 0 - 2000 Hz. The test machine integrates many professional systems, has high feasibility, distinct structural design levels, and high reliability.

[0034] (2) With the design of the added temperature control box, the present invention can not only conduct high-frequency dynamic stiffness tests under different static preloading forces, but also couple the static preloading force and temperature gradient received by the railway fasteners, and test and obtain the lateral and vertical dynamic stiffness and dynamic damping parameters of the railway fasteners under different temperatures, different frequencies, different preloading pressures and temperature gradients. Description of the Drawings

[0035] Figure 1 It is a vertical excitation structure sectional view of Embodiment 1;

[0036] Figure 2 It is an axonometric view of the vertical excitation structure of Embodiment 1;

[0037] Figure 3 It is a schematic diagram of the lateral excitation structure of Embodiment 2;

[0038] Figure 4 It is an axonometric view of the lateral excitation structure of Embodiment 2;

[0039] As shown in the figure, 1 - dynamic excitation system, 101 - main excitation rod, 102 - exciter, 103 - exciter fixing seat, 2 - static preloading system, 201 - support base, 202 - lower platform, 203 - loading upper platform, 204 - upper platform locking device, 205 - guide column, 3 - spring isolation system, 301 - spring lower bearing plate, 302 - spring, 303 - upper positioning plate (lateral friction plate), 4 - test fastener fixing tooling, 401 - test fastener fixing bottom plate, 402 - dynamometer, 403 - fastener sleeper, 404 - test fastener, 405 - temperature control box. Detailed Embodiments

[0040] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0041] Embodiment 1

[0042] As Figure 1-2 shown, a high-frequency dynamic stiffness test machine for railway fasteners includes a dynamic excitation system 1, a static preloading system 2, a spring isolation system 3, a test fastener fixing tooling 4 and a dynamic acquisition system 5.

[0043] The described dynamic excitation system 1 (select German TIRA-50350) provides high-frequency dynamic excitation force with a certain amplitude for railway fasteners, mainly including a main excitation rod 101, an exciter 102, an exciter fixing seat 103, and a signal control and amplification system 104;

[0044] The described static preloading system 2 provides preloading static force for the high-frequency dynamic stiffness of railway fasteners, mainly including a support base 201, a lower platform 202, a loading upper platform 203, an upper platform locking device 204, a guide post 205, and a spring isolation system 3; the support base 201 is placed under the lower platform 202, the tested fastener fixing tooling 4 is installed on the lower platform 202, the loading upper platform 203 is movably arranged on the guide post 205 in the up and down direction and is locked by the upper platform locking device 204, and the spring isolation system 3 is installed under the loading upper platform 203;

[0045] The described spring isolation system 3 includes a spring lower bearing plate 301, a spring 302, and an upper positioning plate 303; the upper end of the spring 302 is fixed to the bottom of the loading upper platform 203 through the upper positioning plate 303, and the lower end is fixed to the spring lower bearing plate 301, and the spring lower bearing plate 301 contacts the tested fastener system.

[0046] The described tested fastener fixing tooling 4 includes a tested fastener fixing bottom plate 401, a dynamometer 402, a fastener sleeper 403, a tested fastener 404, and a temperature control box 405; the fastener sleeper 403 is fixed on the tested fastener fixing bottom plate 401, and a dynamometer 402 (select American Celtron PSD-5TSJTT) is arranged under the fastener sleeper 403, and the fastener system 404 fixes the rail on the fastener sleeper 403.

[0047] The described dynamic acquisition system 5 will collect the preloading force and vibration values received by the tested fastener system under the action of the static preloading system and the dynamic excitation system, mainly including an acceleration signal and a force signal 9. The dynamic acquisition system is a combination of a non-contact laser displacement sensor (select German Micro-Epsilon ILD1420 displacement sensor), a force sensor (select American Celtron PSD-5TSJTT), an amplifier (German TIRA-50350), and a data acquisition system (Hangzhou Yiheng VT9002). When the testing machine works, the static preloading system first loads to the rated static force value, the dynamic excitation system will perform dynamic excitation according to a certain dynamic excitation force value and amplitude, and the arranged testing system will start to collect relevant dynamic parameters.

[0048] This testing machine can perform high-frequency tests on the vertical and horizontal dynamic stiffness of railway fasteners, and the dynamic test frequency range can reach 0 - 2000Hz.

[0049] When performing vertical high-frequency excitation, as Figure 1-2 shown, the exciter 102 is installed on the exciter fixing seat 103. One end of the main excitation rod 101 is connected to the exciter 102, and the other end sequentially passes through the loading upper platform 203, the upper positioning plate 303, and the spring 302 of the static preloading system 2, applying high-frequency excitation to the spring lower bearing plate 301 of the spring isolation system 3, so as to perform high-frequency excitation on the rail, the fastening rail tie 403, and the tested fastener 404 connected by the flange below it. Set the preloading force value of the static preloading system 2 (force value 0 - 150 kN), slowly control the loading upper platform 203 to slowly descend and contact the rail of the tested fastener system, set the tested fastener system to the loading force value, and then lock the upper platform locking device 204 at this time; turn on the exciter system 1, set the excitation force and frequency of the exciter 102, so that the excitation rod 101 contacts the spring lower bearing plate 301 of the spring isolation system 3, and transmit the excitation force and frequency of the exciter 102 to the rail. The tested fastener 404 will generate high-frequency excitation force and frequency, and calculate the dynamic characteristics of the tested railway fastener through the formula k 21 = k 11 + ω 2 m 1 - k i . Among them, k 21 is the dynamic stiffness of the tested fastener system, k 11 is the dynamic stiffness of the excitation point 1 of the excitation rod 101. It is obtained through the F 1 of the excitation point and the displacement u 1 of the excitation contact point (that is k 11 = F 1 / u 1 ), ω is the vibration frequency, m 1 is the equivalent participating vibration mass of the test system (the equivalent connecting piece mass m 11 of the test system can be obtained through the spring isolation system test system connecting piece and the equivalent elastic unit mass m 12 of the elastic unit itself), k i is the equivalent supporting stiffness of the test system, and the equivalent dynamic stiffness of the static load loading vibration isolation spring is measured by the ISO10846 - 5 excitation point measurement method.

[0050] When performing lateral high-frequency excitation, the exciter 102 is installed on the exciter fixing base 103, and the exciter fixing base 103 is installed on the lower platform 202 of the static preloading system 2. The main excitation rod 101 pushes the lateral friction plate 302 of the spring isolation system 3 from the side, thereby providing lateral dynamic excitation to the measured fastener system. As Figure 3 , 4 shown, place the measured fastener system on the lower platform 202 of the static preloading system 2; connect the lateral vibration isolation spring system 3 under the loading upper platform 203, set the preloading force value of the static preloading system 2 (force value 0 - 150 kN), slowly control the loading upper platform 203 to slowly descend and contact the rail of the measured fastener system, and set the fastener to the loading force value. At this time, lock it through the upper platform locking device 204; turn on the exciter system 1, set the excitation force and frequency of the exciter 102, so that the excitation rod 101 generates a lateral excitation force on the lateral friction plate 302 and through the lateral spring (303), and transmit the excitation force and frequency of the exciter 102 to the rail through the flange under the lateral friction plate 302. The measured fastener will generate high-frequency excitation force and frequency. Through the formula k 21 = k 11 + ω 2 m 1 - k i calculate the dynamic characteristics of the measured railway fastener. Among them, k 21 is the dynamic stiffness of the measured fastener system 4, k 11 is the dynamic stiffness of the excitation point 1 of the excitation rod 101. Through the F 1 of the excitation point and the displacement u 1 of the excitation contact point, it is obtained (that is, k 11 = F 1 / u 1 ), ω is the vibration frequency, m 1 is the equivalent participating vibration mass of the test system (the equivalent connecting piece mass m 11 of the test system can be obtained through the spring isolation system test system connecting piece and the equivalent elastic unit mass m 12 of the elastic unit itself), k iTo test the equivalent support stiffness of the system, the equivalent dynamic stiffness of the vibration isolation spring under static load was measured using the excitation point measurement method of ISO10846-5.

Claims

1. A railway fastener high frequency dynamic stiffness test machine, comprising a dynamic excitation system (1), a spring isolation system (3), a fastener fixing device (4) and a dynamic acquisition system (5), It is characterized in that It also includes a static preloading system (2) for providing a preloading static force for the fastener system under test, the dynamic excitation system (1) for providing a dynamic exciting force of 0-2000 Hz for the fastener system under test, and the dynamic acquisition system (5) for acquiring the preloading static force and vibration value of the fastener system under test; The static preloading system (2) comprises a support base (201), a lower platform (202), an upper loading platform (203), an upper platform locking device (204), and a guide column (205); the support base (201) is placed under the lower platform (202); the fastener fixing fixture (4) to be tested is installed on the lower platform (202); the upper loading platform (203) is movably arranged on the guide column (205) and is locked by the upper platform locking device (204); and the spring isolation system (3) is installed under the upper loading platform (203); When the loading upper platform (203) contacts the spring isolation system (3) along the guide column (205) and reaches the preload setting force value, the upper platform locking device (204) holds the loading upper platform (203) through the servo valve hydraulic system and starts working. The static preload force value of the testing machine is adjustable within the adjustment range of 0-150kN; The testing machine further comprises a temperature control box (405), and the fastener fixing fixture (4) and the fastener system to be tested are placed in the temperature control box (405); The dynamic excitation system (1) comprises a main excitation rod (101), an exciter (102), an exciter fixing seat (103) and a signal control and amplification system (104); the exciter (102) is mounted on the exciter fixing seat (103); by adjusting the position and direction of the exciter fixing seat (103), the main excitation rod (101) provides lateral or vertical dynamic excitation to the fastener system under test; One end of the main exciting rod (101) is connected to the exciter (102), and the other end passes through the static preloading system (2) and is inserted into the spring isolation system (3), so as to provide vertical dynamic excitation to the fastener system under test; Alternatively, the main exciting rod (101) pushes the spring isolation system (3) laterally from the side, thereby providing lateral dynamic excitation to the fastener system under test; The test obtained the lateral and vertical dynamic stiffness and dynamic damping parameters of railway fasteners under different temperatures, different frequencies, different preload pressures and temperature gradients.

2. A railway fastener high frequency dynamic stiffness test machine according to claim 1, It is characterized in that The upper platform locking device (204) is arranged on the loading upper platform (203), and uses a hydraulic servo valve system to lock or release the four guide columns (205) of the loading upper platform (203). The intermediate connected hydraulic cylinder drive assembly drives the loading upper platform (203) to move up and down along the guide columns (205) through a hydraulic pump station, and sets the hydraulic value to apply different static preload forces to the spring isolation system (3) below.

3. A high-frequency dynamic stiffness test machine for railway fasteners according to claim 1, characterized in that, the main excitation rod (101) can reach an excitation frequency of 0 - 2000 Hz for the fasteners to be measured.

4. A high-frequency dynamic stiffness test machine for railway fasteners according to claim 1, characterized in that, the spring isolation system (3) includes a spring lower bearing plate (301), a spring (302) and an upper positioning plate (303). The upper end of the spring (302) is fixed to the bottom of the loading upper platform (203) through the upper positioning plate (303), and the lower end is fixed to the spring lower bearing plate (301). The spring lower bearing plate (301) contacts the fastener system to be measured.

5. A high-frequency dynamic stiffness test machine for railway fasteners according to claim 1, characterized in that, the fixture (4) for the fasteners to be measured includes a fixed bottom plate (401) for the fasteners to be measured and a force measuring instrument (402); the fastener system to be measured includes a fastener sleeper (403) and a fastener to be measured (404). The fastener sleeper (403) is fixed on the fixed bottom plate (401) for the fasteners to be measured, and a force measuring instrument (402) is arranged under the fastener sleeper (403). The fastener to be measured (404) fixes the rail on the fastener sleeper (403).

6. A high-frequency dynamic stiffness test machine for railway fasteners according to claim 1, characterized in that, the dynamic acquisition system (5) acquires the pre-loaded static force and vibration quantity values received by the fastener system to be measured, including acceleration signals, force signals, velocity signals and displacement signals.

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