Fatigue test method for energy storage spring and special auxiliary device

Abstract

The invention relates to a fatigue test device and method for an energy storage spring, and the method comprises the following steps: 1, taking the energy storage spring in a to-be-tested high-voltage circuit breaker, measuring the parameters of the energy storage spring, and carrying out the preliminary machining; 2, the energy storage spring obtained after primary machining is installed on a fatigue test device; 3, statically and statically loading the energy storage spring to the compression height H1 on the fatigue test device; 4, initial stress measurement and fatigue test of the energy storage spring are carried out, and test data are obtained; and 5, processing the obtained experimental data to obtain an experimental result. The method comprises the following steps: firstly, performing two-stage compression on a spring to H1 by performing staged static loading, then adjusting the compressed spring and a compression device to a starting point of a maximum compression stroke of a fatigue testing machine, and reserving enough compression displacement space for large-stroke compression fatigue.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage spring testing, and specifically to a fatigue test method and a special auxiliary device for an energy storage spring in a high-voltage circuit breaker. Background Art

[0002] A high-voltage circuit breaker is a key device for control and protection in a power system, and its reliability directly affects the stability of the power system. As one of the core components of the circuit breaker, the energy storage spring is responsible for providing the power for opening and closing operations, and the quality of its performance directly relates to whether the circuit breaker can work properly. As the service life of the circuit breaker increases, the energy storage spring will undergo fatigue failure due to repeated deformation during operation. In order to ensure the safe and stable operation of the power grid, it is particularly important to conduct fatigue detection on the energy storage spring in the high-voltage circuit breaker.

[0003] When the energy storage spring leaves the factory, there are specific requirements for the initial height H0, the compressed height H1 (the opening height of the energy storage spring), and the compressed height H2 (the closing height of the energy storage spring) of the spring, as well as the spring compression loads P1 and P2 at the compressed heights H1 and H2. When the energy storage spring is installed on site, it is first compressed from the initial height H0 to H1, and then during the subsequent opening and closing operations in use, it is manifested as a cyclic displacement transformation during the process of the spring being compressed from H1 to H2. During this process, after the spring may undergo tens of thousands of opening and closing fatigue cycles, it may become loose or strengthened, and finally it is manifested as an increase or decrease in the loads P1 and P2 after tens of thousands of fatigue cycles. When the increase or decrease of P1 and P2 relative to before fatigue exceeds a certain percentage, for example, 10%, it can be considered that the spring has undergone fatigue failure and needs to be replaced in a timely manner. Considering that the stroke between H1 and H2 is usually about 100 mm, while the stroke from H0 to H1 is often larger, ranging from 160 mm to 300 mm. And the total displacement stroke of the hydraulic servo fatigue testing machine is only 150 mm.

[0004] In the prior art, a spring fatigue detection device and method are disclosed, including a base and a support frame; a plurality of clamping components, which include a plurality of clamping members. The plurality of clamping members are elastically slid away from each other and are arranged on the base, and the plurality of clamping members are all adapted to abut against the inner wall of the spring; a pressing-down component, which includes a pressing-down driving member, a lifting plate, a plurality of pressing-down members and a plurality of adjusting members. The pressing-down driving member is installed on the support frame, and the pressing-down driving member is drivingly connected to the lifting plate to drive the lifting plate to move up and down. The plurality of pressing-down members are respectively connected to the lifting plate through the plurality of adjusting members. The plurality of pressing-down members are respectively directly opposite to the plurality of clamping components in the vertical direction. The adjusting member is used to adjust the height of the pressing-down member relative to the lifting plate. By changing the height of the pressing-down member relative to the lifting plate, it is ensured that when the plurality of pressing-down members descend, the deformation amounts of all the springs meet the requirements, so that the detection consistency is better and the detected results are more persuasive. However, this spring fatigue test device has no protection measures, posing a safety hazard to the tester during the test, and the applicable range of the tested springs is small.

[0005] In the prior art, a fatigue degree detection device for spring production is also disclosed, including: a shock-absorbing spring clamping component, a connecting transmission component, a pressing disc and a detection piercing rod; the shock-absorbing spring clamping component includes a lower support plate, a slider, an upper clamping plate, a U-shaped handle and a fixed piercing rod; the top end of the slider is slidably inserted into the first upper sliding groove and is fixedly connected to the bottom side of the lower support plate, and the fixed piercing rod is slidably clamped at one end of the first inner frame through a limit nut; four groups of spline transmission rods are fixed on the top side of the pressing disc, and the spline driving shaft and a group of spline transmission rods are drivingly connected through the connecting transmission component; the detection piercing rod is slidably clamped at the other end of the first inner frame through a limit nut, and the pressing rod is connected to the sleeve sleeved on the detection piercing rod through a thread. It is suitable for shock-absorbing springs of different lengths and sizes, and the detection strength can also be changed, solving the problems of being only applicable to shock-absorbing springs of a single size and inconsistent applied forces during detection. However, this test platform is too complex, only suitable for the detection of small springs, with too high installation accuracy requirements, and most of the transmissions are mechanical transmissions with high installation accuracy requirements.

[0006] In the prior art, there is also disclosed a slow opening and slow closing test device for a circuit breaker spring operating mechanism, which includes a crank arm installed on the side wall of the base and a pair of connecting plates fixedly connected to the side wall of the base. The lower end of the crank arm is provided with a first pin shaft and a second pin shaft. A support seat is installed between the two connecting plates. The two ends of the support seat are installed on the connecting plates in the form of a rotating shaft. The middle of the support seat is a cavity structure, and a thrust ball bearing is installed in the cavity structure. A lead screw passes through the middle of the inner ring of the thrust ball bearing. A nut is screwed on the lead screw. The front end of the lead screw is fixedly provided with a hook device, and the hook head of the hook device hooks on the first pin shaft of the crank arm. During the rotation of the crank arm, the hook in the device will adjust the angle accordingly to ensure that the included angle between the hook and the force-receiving element is within a safe range. However, this test device does not involve an automated control or an integration solution with an external control system, and the accuracy parameters of the device in aspects such as displacement control, force measurement, or angle adjustment are not clearly given in the patent, making it difficult for users to intuitively evaluate its applicability in scenarios with high-precision test requirements.

[0007] In the prior art, there is also disclosed a portable circuit breaker spring fatigue detection and pressure adjustment device and its working method, which is characterized in that: the portable circuit breaker spring fatigue detection and pressure adjustment device includes an upper base, a lower base, a hydraulic cylinder and a pressure sensor arranged between the upper base and the lower base. A fuel pump body and a crank for driving the hydraulic cylinder to move up and down are arranged beside the hydraulic cylinder. The pressure sensor is electrically connected to a digital display pressure gauge through a wire. The portable circuit breaker spring fatigue detection and pressure adjustment device of this invention has a simple structure and reasonable design, which is conducive to efficiently and easily adjusting the spring to the pre-charged energy position. At the same time, it can judge the aging degree of the spring on site, which is conducive to eliminating potential safety hazards. However, this device is only applicable to specific series (HPL / LTB series) of circuit breakers, and the application range is relatively narrow. The manual operation method may have a relatively large labor intensity and a relatively slow detection speed when facing a large number of spring detections.

[0008] In the prior art, a fatigue test mechanism for a GIS circuit breaker energy storage spring is also disclosed, which includes a base. A single-phase motor is fixedly installed at the side end of the upper surface of the base. Two connecting plates are fixedly installed at the top of the base, a fatigue test structure, the fatigue test structure includes a turntable, a pressure regulating structure, the pressure regulating structure includes a connecting groove and a first threaded rod, and a spring heat dissipation structure, the spring heat dissipation structure includes a second belt and a support frame. Through the design and installation of the fatigue test structure and the pressure regulating structure, by adjusting the overall length of the connecting frame and the connecting rod, the pressure on the energy storage spring can be quickly and labor-savingly adjusted according to needs, so that when performing fatigue tests on multiple energy storage springs, corresponding adjustments can be made according to the different test requirements of different energy storage springs and then the tests can be carried out simultaneously, improving the test efficiency. However, the device cannot be compatible with different types of energy storage springs and may not meet diverse detection requirements. There is no quantitative description of the heat dissipation effect of the heat dissipation structure.

[0009] In the prior art, a durability test device for an automotive suspension coil spring is also disclosed, which can shorten the test cycle, improve the test efficiency and has a low cost. It includes a fixed bracket connected to one end of the coil spring A and a movable bracket connected to the other end of the coil spring A. The movable bracket is connected to a driving mechanism, and at least 2 groups of movable brackets and coil spring A are connected to the driving mechanism, so that while some of the coil spring A are in a tensile motion, the rest of the coil spring A are in a compressive motion. Since the coil spring has an energy storage function and the law of conservation of energy and the principle of action and reaction are skillfully applied, and multiple coil spring tests can be completed in one test, the test efficiency is almost doubled, the test cycle is shortened, and the cost is reduced. However, this test device is mainly aimed at automotive suspension coil springs, and the applicability to other types of springs (such as special-shaped springs, extra-large or micro springs) is not mentioned, making it difficult to directly apply to the durability test of non-automotive suspension springs, restricting the application field of the device. It only focuses on the tensile and compressive durability tests of the spring and does not involve the detection function of other important performance parameters of the spring, and cannot comprehensively evaluate the performance of the spring under complex working conditions, which may lead to misjudgment of the spring quality.

[0010] In the prior art, a high-voltage circuit breaker energy storage spring detection device and a detection method are also disclosed, including a fixed base, a spring compression and release assembly, a pressure sensor, and a spring relaxation timer. A plurality of spring detection installation grooves are provided on the fixed base, and the spring to be detected is installed in the spring detection installation groove. One end of the spring to be detected is fixed to the bottom of the spring detection installation groove, and the other end is fixed to the spring compression and release assembly; the spring compression and release assembly is slidably arranged along the spring detection installation groove, and the spring compression and release assembly is used to compress the spring to be detected; it can detect multiple springs to be detected simultaneously. The pressure sensor detects the pressure value, and the spring relaxation timer detects the spring rebound recovery time to reflect the opening and closing time, so that multiple springs can be detected simultaneously, and the state information of the springs can be obtained and transmitted to an external processing terminal. No detailed description is made on the adaptability of high-voltage circuit breaker energy storage springs of different specifications, and further adjustment or improvement may be required to meet all situations. The room for improvement in the automation level of the device is not mentioned, such as whether the full automation control of the detection process can be further realized.

[0011] In the prior art, a compression spring fatigue test device and a test method are also disclosed, including a cam mechanism connected to the piston rod of the piston assembly in the piston cylinder. The top of the piston cylinder is hermetically connected with a cover body, and the cover body is in threaded fit with the inner wall of the piston cylinder. A force sensor is fixedly connected to the bottom wall of the cover body. The chamber formed by the cover body, the inner wall of the piston cylinder, and the piston serves as a closed space for accommodating the compression spring; the steps of the test method include: obtaining the compression amount of the compression spring specimen and performing a compression test; detecting the surface defects of the compression spring specimen during the test process. The present invention ingeniously combines the spring fatigue test and the surface defect detection. It can not only stably carry out the fatigue test on the compression spring, but also conveniently detect the surface defects of the compression spring at any time / phase during the spring fatigue test process, realizing the synchronization of the penetration process and the spring fatigue test loading, with simpler operation and no mutual influence. However, the device structure is relatively complex, which may lead to a relatively high manufacturing cost and a relatively large maintenance difficulty. No mention is made of the detection effect differences and corresponding adjustment methods for compression springs of different materials and different specifications.

[0012] In summary, there are three major difficulties in the existing fatigue tests on energy storage springs in high-voltage circuit breakers: 1) Regarding the problem that mechanical fatigue loading devices cannot accurately provide real-time information such as load and displacement during fatigue, which affects the final evaluation accuracy of fatigue tests. Considering using a hydraulic servo fatigue testing machine to conduct fatigue tests, but the maximum single movement stroke of the hydraulic servo fatigue testing machine is limited to ±75 mm, there is a limitation of a short stroke and it is not suitable for spring fatigue tests with large strokes; 2) Regarding the blank of fatigue tests with large strokes, there is no corresponding experimental method for fatigue tests, and during the fatigue test of energy storage springs, due to the large number of required test times, the unloading link during the test process often leads to significant test errors; 3) During the fatigue test of energy storage springs, in view of the possibility of fatigue fracture, it is necessary to construct a corresponding protection device to ensure the safety of the test process. Summary of the Invention

[0013] The purpose of the present invention is to solve the above-mentioned deficiencies of the existing technologies, and thus provides a fatigue test method for energy storage springs. This method conducts hierarchical static loading. First, the spring is compressed to H1 at two levels, and then the compressed spring together with the compression device is adjusted back to the starting point of the maximum compression stroke of the fatigue testing machine, reserving enough compression displacement space for large-stroke compression fatigue.

[0014] A fatigue test method for energy storage springs includes the following steps:

[0015] Step 1: Take the energy storage spring in the high-voltage circuit breaker to be tested, measure the parameters of the energy storage spring and then conduct preliminary processing.

[0016] Step 2: Install the preliminarily processed energy storage spring on the fatigue test device.

[0017] Step 3: Conduct hierarchical static loading on the energy storage spring on the fatigue test device to the compressed height H1.

[0018] Step 4: Measure the initial force of the energy storage spring and conduct fatigue tests, and obtain test data.

[0019] Step 5: Process the obtained experimental data to obtain the test results.

[0020] Measuring the parameters of the energy storage spring includes the initial length H0 and outer diameter D of the energy storage spring in the high-voltage circuit breaker to be tested.

[0021] The preliminary processing includes the following steps: Process the flatness of the upper and lower contact surfaces of the energy storage spring in the high-voltage circuit breaker to be tested until the flatness reaches 0.1 - 0.5 mm.

[0022] The specific content of Step 2 is as follows:

[0023] Step 21: Unscrew Nut 1. After removing the upper steel plate, place the lower end of the preliminarily processed energy storage spring into the lower cylinder of the lower steel plate, then place the upper steel plate, and put the upper end of the preliminarily processed energy storage spring into the upper cylinder of the upper steel plate. Re-screw Nut 1 to connect the energy storage spring and the auxiliary device into a whole; then connect the connecting column on the upper steel plate to the upper column of the fatigue testing machine.

[0024] Step 22: Unlock the crossbeam locking device of the fatigue testing machine, and let the auxiliary device descend with the upper column until the lower surface of the lower steel plate contacts the lower actuator of the fatigue testing machine, and the lower steel plate changes from being suspended to contacting the lower actuator.

[0025] Step 23: Screw down Nut 2 until the height between Nut 2 and Nut 3 is slightly less than the initial height H0 of the spring. Continue to adjust the crossbeam of the fatigue testing machine so that the upper steel plate contacts the upper surface of the spring. Control the lower actuator to move slightly upward. At this time, the load in the load window of the fatigue testing machine changes from 0 to a small compression load. Rotate Nut 1 until it touches the upper surface of the upper steel plate. At this time, measure the height difference between the inner surfaces of the upper and lower steel plates. If it is the initial height H0 of the spring, lock the crossbeam of the fatigue testing machine. Thus, the installation of the energy storage spring is completed.

[0026] Step 3 specifically includes:

[0027] Step 31: Calculate the static compression stroke L0 of the energy storage spring = H0 - H1. The compression test of the energy storage spring is divided into two levels of static loading, and the single - time static compression amount L1 = L0÷2.

[0028] Step 32: Lock the upper crossbeam of the fatigue testing machine, keep the upper column stationary, screw down Nut 2 so that the distance between Nut 2 and Nut 1 is greater than L1. Operate the lower actuator of the fatigue testing machine to rise, so that the lower actuator compresses upward by L1 at a set compression frequency; then, lock Nut 1 tightly against the upper surface of the upper steel plate. Screw down Nut 2 until the distance between Nut 1 and Nut 2 is greater than L1. Then, the lower actuator moves slightly downward to ensure that the tightened Nut 4 is under pressure.

[0029] Step 33: The lower actuator descends to the initial position, then loosen the lock of the upper crossbeam and move the upper column downward by the same distance L1 so that the lower steel plate contacts the lower actuator.

[0030] Step 34: Control the lower actuator to move upward, compress the energy storage spring to a height of H1, measure the size and length of the energy storage spring in the current compressed state, and confirm that the height meets H1.

[0031] Step 35: Screw Nut 1 tightly to a position above the upper steel plate. After screwing tightly, loosen Nut 2 to ensure that the loosening displacement of Nut 2 is at least H1 - H2. The lower actuator descends to the initial position, then loosen the lock of the upper crossbeam and move the upper column downward by the same distance so that the lower steel plate contacts the lower actuator.

[0032] Step 4 specifically includes the following:

[0033] Step 41: Operate the lower actuator to rise at a set frequency, so that the lower steel plate continues to compress the energy storage spring to the compression height H2, and record the force value P2 of the energy storage spring at this time; then operate the lower actuator to descend at the set frequency, so that the energy storage spring returns to the position at the initial compression height H1, and record the force value P1 of the energy storage spring at the compression height H1.

[0034] Step 42: Repeat Step 41 at least four times, and record the force values of the energy storage spring at the compression height H1 and the compression height H2 each time.

[0035] Step 43: After the recording is completed, conduct a fatigue test for N cycle times at the set frequency.

[0036] Step 44: After the fatigue test of N cycles is completed, repeat Step 41 at least four times, and record the force values of the energy storage spring at the compression height H1 and the compression height H2 each time.

[0037] The fatigue test includes the following steps:

[0038] After the energy storage spring returns to the compression height H1, operate the lower actuator to rise at the set frequency, so that the lower steel plate continues to compress the energy storage spring to the compression height H2; then operate the lower actuator to descend at the set frequency, so that the energy storage spring returns to the position at the initial compression height H1.

[0039] Step 5 specifically includes the following:

[0040] Step 52: According to the calculation formula of the average force Substitute the numerical values of multiple initial P1 and P2 recorded before the N - cycle fatigue test to obtain the average force at the initial compression height H1 The average force at the compression height H2 of the size;

[0041] Step 53: According to the calculation formula of the average force, substitute the numerical values of multiple P1 and P2 recorded after the N - cycle fatigue test to obtain the average force at the compression height H1 after the fatigue test The average force at the compression height H2 of the size;

[0042] Step 54: According to the relaxation rate formula Calculate the relaxation rate at each stage.

[0043] The present invention also provides a fatigue test device for an energy storage spring, including a fatigue testing machine and an auxiliary device;

[0044] The auxiliary device includes an upper steel plate and a lower steel plate that are parallel to each other vertically. The upper steel plate is fixed to the upper column of the fatigue testing machine through a connecting column;

[0045] Through holes are provided at the four corners of the upper steel plate and the lower steel plate. Four screw rods are vertically inserted into the corresponding through holes of the upper steel plate and the lower steel plate. The upper steel plate and each screw rod are limited by a first nut and a second nut, and the lower steel plate and each screw rod are fastened by a third nut and a fourth nut;

[0046] Cylinders for positioning the energy storage spring in the high-voltage circuit breaker to be tested are fixed on the opposite surfaces of the upper steel plate and the lower steel plate.

[0047] The inner diameter of the cylinder is not less than the outer diameter D of the energy storage spring, and the total height of the two cylinders is less than the minimum height H2 of the spring compression fatigue.

[0048] The width of the upper steel plate and the lower steel plate is less than the distance between the two columns of the hydraulic servo fatigue testing machine, and the height of the screw rod is less than the distance between the crossbeam and the base of the fatigue testing machine.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] 1) The present invention of the patent for invention creatively proposes a fatigue test method for the energy storage spring. Through staged displacement loading, static compression and dynamic fatigue at different elevation positions of the spring are realized. The process from H0 to H1 is static compression, and the process from H1 to H2 is dynamic fatigue. The total stroke of this compression process far exceeds 150 mm. The maximum possible spring compression stroke can reach about 400 mm. By means of staged static loading, the problem of static compression and fatigue tests of energy storage springs with different compression strokes on a hydraulic servo fatigue testing machine with a stroke of only ±75 mm is solved. According to the load attenuation formula, the load attenuation degree at each stage is calculated. The test results are all within the technical requirements for the fatigue test of the energy storage spring for electrical equipment and the "Technical Conditions for Hot-Rolled Cylindrical Helical Compression Springs" GB / T 23934-2015. The real-time display of load and displacement has higher test data accuracy compared with the traditional mechanical spring fatigue test device, can accurately evaluate the fatigue loss of the energy storage spring, provides a strong guarantee for the reliability and service life of the high-voltage circuit breaker, fills the blank for the fatigue test method of the energy storage spring with a large stroke, and this method is applicable to the fatigue tests of various different types of springs.

[0051] 2) The test process protection device of the present invention of the patent for invention is different from other protection methods. It is impossible to see the test process and take relevant measures for the test at any time, or the protection efficiency is low and effective protection cannot be truly obtained. This protection method improves the efficiency of precise protection. When the energy storage spring is compressed to the second stress point, there is only a relatively short visual space, effectively protecting the safety of the equipment and the test personnel.

[0052] Through the method of hierarchical loading, the present invention can not only conduct fatigue tests on the energy storage springs in high-voltage circuit breaker equipment, but also be applied to the compression fatigue of other types of springs. The load-displacement control parameters throughout the process can be monitored and recorded, and the applicable range is wide. For springs with a large compression stroke, large-stroke compression can be achieved through hierarchical static compression, reserving enough dynamic fatigue compression stroke for the fatigue testing machine. Furthermore, a protection device after the spring fatigue fracture is designed to avoid risks to the testers during the test, building a solid safety line for spring test work and improving the overall efficiency and quality of the detection work.

[0053] This application protects the safety of personnel during the test by installing a cylindrical protection device; this application is applicable to the fatigue tests of various energy storage springs, and is installed on a fatigue testing machine, and the working environment, working accuracy and error are all smaller than the error brought by mechanical transmission; this application clarifies the plan for each step in the test, gives the pressure stroke that needs to be moved or applied for each step, and the test is accurate and highly standardized; this application has a wide application range and does not require manual testing, only the installation requires manual operation; this application can test a variety of energy storage spring types and has high compatibility. During the test, the influence of heat generated during the fatigue process of the energy storage spring is controlled by controlling the frequency of the fatigue test; this application can not only test energy storage springs, but also test various types of springs, and is applicable to springs that meet the linear working stroke; this application has a simple device structure, is convenient for production and installation, and has strong adaptability to the fatigue tests of springs with different working strokes. Description of the Drawings

[0054] Figure 1 It is a schematic structural diagram of the auxiliary device of the fatigue test device of the present invention;

[0055] Figure 2 It is a schematic structural diagram of the fatigue test device of the present invention;

[0056] Figure 3 It is a process diagram of hierarchical static loading on the energy storage spring;

[0057] Figure 4 It is a process diagram of force measurement and fatigue test. Detailed Embodiment

[0058] The present invention provides a fatigue test method for an energy storage spring, including the following steps:

[0059] Step 1: Sampling the energy storage spring in the high-voltage circuit breaker to be tested

[0060] Measure the initial values of the spring such as the initial length H0, outer diameter D, spring wire diameter d, and pitch t of the energy storage spring in the high-voltage circuit breaker to be tested, and present them clearly and accurately in the form of a chart before the test.

[0061] Process the contact surface of the energy storage spring on a fatigue testing machine until the flatness reaches 0.1 - 0.5 mm to ensure its perfect parallelism, thus avoiding problems caused by uneven stress during the fatigue test of the energy storage spring.

[0062] Step 2: Install the preliminarily processed energy storage spring on the fatigue test device

[0063] The fatigue testing machine is equipped with an upper column and a lower actuator. The upper column is equipped with an upper steel plate tightly fixed by bolts. The upper steel plate is designed with four evenly distributed round holes. The connection between the upper and lower steel plates is realized through a set of screw rods (4 pieces) and four groups of locking nuts (16 pieces). Taking a single screw rod as an example, two locking nuts are installed on both sides of the upper steel plate and both sides of the lower steel plate, with a total of four locking nuts, named nut one 6, nut two 7, nut three 9, and nut four 10 from top to bottom. Among them, the upper steel plate is moved within the test range through nut one 6 and nut two 7, and nut three 9 and nut four 10 firmly fasten the lower steel plate in place. The lower actuator of the fatigue testing machine is integrated with a displacement sensor, which is used to measure the displacement change of the actuator in real time, and thus indirectly measure the deformation or displacement of the test sample. Its maximum stroke range can reach ±75 mm.

[0064] Step 21: Unscrew nut one 6, remove the upper steel plate 1, put the lower end of the preliminarily processed energy storage spring into the lower cylinder 4 of the lower steel plate 5, then place the upper steel plate 1, and put the upper end of the preliminarily processed energy storage spring into the upper cylinder 2 of the upper steel plate 1. Screw nut one 6 back in to connect the energy storage spring and the auxiliary device into a whole; then connect the connecting column 14 on the upper steel plate 1 to the upper column 13 of the fatigue testing machine;

[0065] Step 22: Unlock the crossbeam locking device of the fatigue testing machine, let the auxiliary device descend together with the upper column 13 until the lower surface of the lower steel plate 5 contacts the lower actuator 15 of the fatigue testing machine, and the lower steel plate changes from being suspended to contacting the lower actuator;

[0066] Step 23: Screw down nut two 7 until the height between nut two 7 and nut three 9 is slightly less than the initial height H0 of the spring. Continue to adjust the crossbeam 11 of the fatigue testing machine so that the upper steel plate 1 contacts the upper surface of the spring. Control the lower actuator to move slightly upward. At this time, the load in the load window of the fatigue testing machine changes from 0 to a small compression load. Rotate nut one 6 until it contacts the upper surface of the upper steel plate 1. At this time, measure the height difference between the inner surfaces of the upper and lower steel plates 5. If it is the initial height H0 of the spring, lock the crossbeam of the fatigue testing machine. Thus, the installation of the energy storage spring is completed.

[0067] Step 3: Apply a graded static load to the energy storage spring on the fatigue test device until the compression height H1 is reached;

[0068] Step 31: Calculate the static compression travel distance of the energy storage spring: Initial height H0 - Compressed height H1 = Static compression travel distance L0. The energy storage spring compression test is divided into two - stage static loading, and the static compression travel distance L0÷2 = Single - stage static compression amount L1.

[0069] Step 32: Lock the upper crossbeam of the fatigue testing machine, keep the upper column stationary, rotate nut two 7 downward so that the distance between nut two 7 and nut one 6 is greater than L1. Operate the lower actuator of the fatigue testing machine to rise, so that its lower actuator compresses upward by L1. Adjust the test compression frequency on the detection and control system to 0.05 - 0.3 HZ. Subsequently, lock nut one 6 tightly on the upper surface of the upper steel plate 1 on the screw rod. Rotate nut two 7 downward until the distance between nut one 6 and nut two 7 is greater than L1. Then, slightly lower the lower actuator to ensure that the tightened nut four 10 is under pressure.

[0070] Step 33: Lower the lower actuator to the initial position, then loosen the upper crossbeam lock and move the upper column downward by the same distance L1 so that the lower steel plate touches the lower actuator.

[0071] Step 34: Then, control the lower actuator 15 to move upward, compress the energy storage spring to the height H1, measure the size length of the energy storage spring in the current compressed state. Use a long steel ruler longer than the compressed height to measure the inner height at the middle position of the pressure plate to see if the height meets the set height of H1. When it meets, record the current load P1. If it does not meet, adjust the action of the lower actuator 15 according to the measured value until the energy storage spring is compressed to the height H1. At this point, the upper column has moved downward by the compression travel distance L0 in total.

[0072] Step 35: Tighten nut one 6 to a position above the upper steel plate. After tightening, loosen nut two 7 to ensure that the loosening displacement of nut two 7 covers at least the maximum dynamic compression displacement H1 - H2 of the energy storage spring during fatigue testing. The loosening displacement of nut two 7 is greater than the test displacement of the energy storage spring fatigue test to prevent the upper steel plate from hitting nut two 7. Then, lower the lower actuator to the initial position, then loosen the upper crossbeam lock and move the upper column downward by the same distance so that the lower steel plate touches the lower actuator.

[0073] Step 4: Measure the initial force of the energy storage spring and conduct a fatigue test, and obtain test data;

[0074] Step 41: Operate the lower actuator to rise at a frequency of 0.05 - 0.3 HZ, so that the lower steel plate continues to compress the energy storage spring to the compressed height H2, and record the force value P2 of the energy storage spring at this time. Then, operate the lower actuator to descend at the set frequency, so that the energy storage spring returns to the position at the initial compression height H1, and record the force value P1 of the energy storage spring at the compressed height H1.

[0075] Step 42: Repeat the above Step 41 at least four times, and record in detail the force values of the energy storage spring at the compression height H1 and the compression height H2 each time. These values are used as the key data for evaluating the bearing capacity of the spring before the formal fatigue test.

[0076] Step 43: Conduct a fatigue test with N cycle times at a set frequency.

[0077] The fatigue test includes the following steps:

[0078] After the energy storage spring returns to the compression height H1, operate the actuator to rise at a set frequency, so that the lower steel plate continues to compress the energy storage spring to the compression height H2; then operate the actuator to descend at a set frequency, so that the energy storage spring returns to the position at the initial compression height H1.

[0079] Step 44: After completing the fatigue test with N cycles, repeat Step 42 at least four times, and record the force values of the energy storage spring at the compression height H1 and the compression height H2 each time. These values are used as important data for evaluating the performance change of the spring after a long-term fatigue test.

[0080] Step 5: Process the obtained experimental data to obtain the test results

[0081] Check the theoretical values F1 and F2 of the initial data of the energy storage spring when it leaves the factory.

[0082] Step 52: According to the calculation formula of the average force Substitute the numerical values of multiple initial P1 and P2 recorded before the N - cycle fatigue test to obtain the average force at the initial compression height H1 The average force at the compression height H2 of the size.

[0083] Step 53: According to the calculation formula of the average force, substitute the numerical values of multiple P1 and P2 recorded after the N - cycle fatigue test to obtain the average force at the compression height H1 after the fatigue test The average force at the compression height H2 of the size.

[0084] Step 54: According to the relaxation rate formula Calculate the relaxation rate at each stage.

[0085] The present invention also provides a fatigue test device for an energy storage spring, such as Figure 1-2, a fatigue testing machine and an auxiliary device. The auxiliary device includes an upper steel plate 1 and a lower steel plate 5 which are parallel to each other up and down. The upper steel plate 1 is fixed to the upper column of the fatigue testing machine through a connecting column 14. Through holes are opened at the four corners of the upper steel plate 1 and the lower steel plate 5. Four screw rods 8 are vertically inserted into the corresponding through holes of the upper steel plate 1 and the lower steel plate 5. The upper steel plate 1 and each screw rod 8 are limited by a first nut 6 and a second nut 7, and the lower steel plate 5 and each screw rod 8 are fastened by a third nut 9 and a fourth nut 10. Upper cylinders 2 and lower cylinders 4 for positioning the energy storage spring in the high-voltage circuit breaker to be tested are fixed on the opposite surfaces of the upper steel plate 1 and the lower steel plate 5. The inner diameters of the upper cylinder 2 and the lower cylinder 4 are not less than the outer diameter D of the energy storage spring 3, the total height of the upper cylinder 2 and the lower cylinder 4 is less than the minimum height H2 of spring compression fatigue, the width of the upper steel plate 1 and the lower steel plate 5 is less than the distance between the two columns 16 of the hydraulic servo fatigue testing machine, the height of the screw rod 8 is less than the distance between the cross beam 11 and the base 17 of the fatigue testing machine, the thickness range of the upper steel plate 1 and the lower steel plate 5 is 20 - 30 mm, the width is 400 - 600 mm, and through holes with a diameter of 30 - 40 mm are designed at the four corners of the steel plates.

[0086] The outer diameters of the upper cylinder 2 and the lower cylinder 4 are 300 - 350 mm, and the thickness is 5 - 15 mm. Four ear structures for stability extend from the periphery of the upper cylinder 2 and the lower cylinder 4, and the thickness of the ear structures is 8 - 10 mm, so that they can be firmly installed on the upper and lower steel plates of the fatigue testing machine through bolts to ensure the reliability of safety protection. The height of the cylinder is 120 - 150 mm, and they are arranged symmetrically up and down, and the total height of the two is slightly less than the minimum height H2 of spring compression fatigue. During the spring fatigue process, it is always in a high energy storage state. In case of fracture and flying out, the harm is extremely great. The existence of this protection device ensures that once the spring breaks during the fatigue test, the two or more broken springs will be blocked by the upper and lower cylinder covers at the moment of ejection and will not fly out to damage the equipment or the test personnel.

[0087] Embodiment

[0088] In order to verify the feasibility of the above method, an equal-proportion fatigue test is carried out on the energy storage spring of a high-voltage circuit breaker with an initial length of 600 mm, and the fatigue test of the energy storage spring is carried out according to the above method. The specific implementation is as follows:

[0089] 1. The selected energy storage spring has an initial height H0 of 600 mm, an outer diameter size of 226 mm, a spring wire diameter of 30 mm, and a spring pitch of 74 mm. The contact section of the energy storage spring is finely processed to ensure flatness;

[0090] Table 1 Dimensions of the test energy storage spring

[0091]

[0092] 2. Use a hydraulic servo fatigue testing machine 11, which has an upper column 13 and a lower actuator 15. The diameter of the upper column 13 is 100 mm, and the diameter of the lower actuator 15 is 120 mm. The distance between the two columns on both sides of the fatigue testing machine is 762 mm, the standard vertical space is 645 - 2295 mm, and the maximum single movement stroke of the lower actuator is ±75 mm. Process a steel plate with dimensions of 480 mm × 480 mm × 28 mm, connect it to the connecting column 14 with bolts of M20 × 130 mm, and process through holes with a diameter of 30 mm at the four corners of the steel plate. Design a cylinder with an outer diameter of 325 mm, an inner diameter of 314 mm, and a height of 150 mm as the protection device 2 according to the size of the steel plate. There are four evenly distributed ears with a thickness of 8 mm on the cylinder, which are respectively connected to the steel plate with bolts of M12 × 50 mm. The lower steel plate is connected to the upper steel plate through the connecting column and is not bolted to the lower actuator. The lower actuator can move freely up and down, contacting or not contacting the lower steel plate, and actions such as static compression and dynamic fatigue are achieved through the displacement of the lower actuator. The lower steel plate is also installed with a lower cylinder 4.

[0093] Position the energy storage spring 3 in the central area of the steel plate, and use four M28 × 1000 mm screws 8 to pass through the four 30 - mm - diameter through holes on the steel plate. Tighten the lower steel plate 5 through nut three 9 and nut four 10. At the same time, lock nut one 6 above the upper steel plate 1, and the distance between nut two 7 and nut one 6 is 118 mm.

[0094] Unscrew nut one 6, remove the upper steel plate 1, then place the lower end of the pre - processed energy storage spring into the lower cylinder 4 of the lower steel plate 5, then place the upper steel plate 1, and put the upper end of the pre - processed energy storage spring into the upper cylinder 2 of the upper steel plate 1. Screw nut one 6 back in to connect the energy storage spring and the auxiliary device into a whole; then connect the connecting column 14 on the upper steel plate 1 to the upper column 13 of the fatigue testing machine.

[0095] Unlock the crossbeam locking device of the fatigue testing machine, let the auxiliary device move downward with the upper column 13 until the lower surface of the lower steel plate 5 contacts the lower actuator 15 of the fatigue testing machine, and the lower steel plate changes from being suspended to contacting the lower actuator.

[0096] Unscrew nut two 7 until the height between nut two 7 and nut three 9 is slightly less than the initial height H0 of the spring. Continue to adjust the crossbeam 11 of the fatigue testing machine so that the upper steel plate 1 contacts the upper surface of the spring. Control the lower actuator to move slightly upward. At this time, the load in the load window of the fatigue testing machine changes from 0 to a small compression load. Rotate nut one 6 until it contacts the upper surface of the upper steel plate 1. At this time, measure the height difference between the inner surfaces of the upper and lower steel plates 5. If it is the initial height H0 of the spring, lock the crossbeam of the fatigue testing machine. Thus, the installation of the energy storage spring is completed.

[0097] 3. Calculate the compression stroke distance of the energy storage spring: Initial height H0 - Load-bearing height H1 = Compression stroke distance L0 = 180 mm, Single static compression amount L1 = L0÷2 = 90 mm, as Figure 3-4 , during the operation fatigue test, nut two 7 moves downward by L1 in advance, and the lower actuator 15 of the testing machine compresses upward by L1. At this time, perform a downward rotation and locking treatment on nut one 6 and nut two 7 above the upper steel plate 1, so that nut one 6 locks the upper steel plate 1. Use a steel ruler to accurately measure the length of the energy storage spring 3, and its length is 510 mm. Immediately afterwards, lower the lower actuator 15 simultaneously to ensure that nut four 10 bears the spring pressure and prevent the energy storage spring 3 from deforming and making errors during the synchronous movement of the upper and lower steel plates of the actuator 15. The lower actuator moves downward by a distance of L1 and returns to the initial position. Then loosen the upper crossbeam of the fatigue testing machine and move the upper crossbeam to move the upper column 13 downward by a distance of L1 so that the lower steel plate 5 touches the lower actuator 15. Nut two 7 moves downward by L1 in advance, and the lower actuator 15 compresses upward by an amount of L1. Nut one 6 above the upper steel plate 1 is locked downward, and at the same time nut two 7 rotates downward by L1, and measure the length of the energy storage spring 3. The result is 420 mm. At this time, the cumulative compression stroke distance of the spring reaches L0. The lower actuator 15 moves downward by L1, then loosen the hydraulic lock of the upper crossbeam, move the upper crossbeam to lower the upper column 13 until the lower steel plate 5 touches the lower actuator 15, and the spring reaches the predetermined compression height H1, and ensure that the lower steel plate returns to the lowest position to reserve enough compression space for the subsequent fatigue test. Rotate nut two 7 downward, and the downward travel is △H = H1 - H2.

[0098] 4. As Figure 4 , after recording the force value P1 of the energy storage spring 3 at the initial compression height H1, immediately adjust the fatigue testing machine 11 in the detection and control system to run at a frequency of 0.1 HZ, so that the lower actuator 15 continues to compress the energy storage spring 3 to the compression height H2, and record the force value P2 of the energy storage spring 3 at this time; immediately afterwards, control the fatigue testing machine 11 at a speed of 0.1 HZ again to make the energy storage spring 3 return to the position at the initial compression height H1. Repeat the above actions four times to measure the P1 and P2 values and take the average and to eliminate the influence brought by various errors.

[0099] Control the detection and control system to adjust the fatigue testing machine 11 to perform 10,000 cycle fatigue tests on the energy storage spring 3 at a frequency of 0.1 HZ. After the test is completed, measure the P1 and P2 values four times again in the same way as above and take the average and as the performance change after the fatigue test.

[0100] 5. According to the calculation formula of the average force Record the values of the four initial P1 and P2 at a working rate of 0.1 HZ on the fatigue testing machine 11, and substitute the data in Table 2 into the formula to obtain the initial Substitute the values of P1 and P2 after 10,000 fatigue cycles recorded four times, and substitute them into the calculation formula of the average force to obtain the value after the fatigue test According to the relaxation rate formula Calculate the relaxation rate ε at each stage p 1 = 0.762%, ε p 2 = -0.05%. According to the regulations in GB / T 23934-2015 "Technical Conditions for Hot-Rolled Cylindrical Helical Compression Springs": The load limit deviation at the specified height, that is, the relaxation rate, is defined as Grade 1, Grade 2, and Grade 3 at ±5%, ±10%, and ±15% respectively. In the power industry, generally only load limit deviations above Grade 2 are accepted, that is, ±10%. The load limit deviations of the spring in this test at the compression strokes at H1 and H2 both meet the technical conditions

[0101] Table 2

[0102]

Claims

1. A fatigue test method for energy storage springs, characterized in that: The following steps are involved: Step 1: Take the energy storage spring from the high-voltage circuit breaker to be tested, measure the parameters of the energy storage spring and then perform preliminary processing; Step 2: Install the energy storage spring after preliminary processing on the fatigue testing device; Step 3: statically load the energy storage spring in stages to a compression height H1 on a fatigue test device; Step 4: Initial force measurement and fatigue test of energy storage spring, and obtain test data; Step 5: Process the acquired experimental data to obtain the test results.

2. A fatigue test method for energy storage spring according to claim 1, characterized in that: The energy storage spring parameters to be measured include the initial length H0 and the outer diameter D of the energy storage spring in the high-voltage circuit breaker to be tested; The initial processing includes the following steps: flattening the upper and lower contact surfaces of the energy storage spring in the high-voltage circuit breaker to be tested until the flatness reaches 0.1 to 0.5 mm.

3. A fatigue test method for energy storage spring according to claim 1, characterized in that: The step 2 is specifically as follows: Step 21, unscrew nut one (6), remove the upper steel plate (1), place the lower end of the energy storage spring after preliminary processing into the lower cylinder (4) of the lower steel plate (5), then place the upper steel plate (1), place the upper end of the energy storage spring after preliminary processing into the upper cylinder (2) of the upper steel plate (1), re-screw nut one (6), and connect the energy storage spring and the auxiliary device into a whole; then connect the connecting column (14) on the upper steel plate (1) to the upper column (13) of the fatigue testing machine; Step 22, unlock the crossbeam locking device of the fatigue testing machine, and allow the auxiliary device to move downward along with the upper column (13) until the lower surface of the lower steel plate (5) contacts the lower actuator (15) of the fatigue testing machine, and the lower steel plate changes from being suspended in the air to being in contact with the lower actuator; Step 23, screw down nut two (7) until the height between nut two (7) and nut three (9) is slightly less than the initial height H0 of the spring, continue to adjust the fatigue testing machine crossbeam (11) to make the upper steel plate (1) contact the upper surface of the spring, control the lower actuator to move slightly upward, at this time, the load in the fatigue testing machine load window changes from 0 to a small compression load, rotate nut one (6) until it contacts the upper surface of the upper steel plate (1), at this time, measure the height difference between the inner surfaces of the upper and lower steel plates (5), if it is the initial height H0 of the spring, lock the fatigue testing machine crossbeam, and the energy storage spring installation is completed.

4. A fatigue test method for energy storage spring according to claim 1, characterized in that: Step 3 specifically includes: Step 31, calculate the static compression stroke L0=H0-H1 of the energy storage spring, the compression test of the energy storage spring is divided into two levels of static loading, and the single static compression amount L1=L0÷2; Step 32, the upper crossbeam of the fatigue testing machine is locked, the upper column is immobile, the second nut (7) is screwed down, so that the distance between the second nut (7) and the first nut (6) is greater than L1, and the lower actuator of the fatigue testing machine is operated to rise, so that the lower actuator is compressed upward by L1 at a set compression frequency; then, after locking the first nut (6) tightly against the upper surface of the upper steel plate (1), the second nut (7) is screwed down until the distance between the first nut (6) and the second nut (7) is greater than L1, and then the lower actuator is slightly moved down to ensure that the tightened nut four (10) is under pressure; Step 33, the lower actuator moves downward to the initial position, and then the upper crossbeam lock is released to move the upper column downward the same distance L1, so that the lower steel plate contacts the lower actuator; Step 34, control the lower actuator (15) to move upward, compress the energy storage spring to a height H1, measure the length of the energy storage spring in the current compressed state, and confirm that the height meets H1; Step 35, tighten nut 1 (6) to the position above the upper steel plate. After tightening, loosen nut 2 (7) to ensure that the loose displacement of nut 2 (7) is at least H1-H2. The lower actuator moves down to the initial position, then release the upper beam lock and move the upper column down the same distance so that the lower steel plate contacts the lower actuator.

5. The fatigue test method of an energy storage spring according to claim 1, characterized in that: Step 4 is as follows: Step 41, operating the lower actuator at a set frequency to ascend, so that the lower steel plate continues to compress the energy storage spring to a compression height H2, and recording the force value P2 of the energy storage spring at this time; then operating the lower actuator at a set frequency to descend, so that the energy storage spring returns to the position at the initial compression height H1, and recording the force value P1 of the energy storage spring at the compression height H1; Step 42, repeat step 41 at least four times, and record the force values ​​of the energy storage spring at the compression height H1 and the compression height H2 each time; Step 43: After the recording is completed, a fatigue test is performed at a set frequency for N cycles; Step 44, after completing the fatigue test for N cycles, repeat step 41 at least four times, and record the force values ​​of the energy storage spring at the compression height H1 and the compression height H2 each time.

6. A fatigue test method for energy storage spring according to claim 1, characterized in that: Fatigue testing includes the following steps: After the energy storage spring returns to the compression height H1, the lower actuator is operated at the set frequency to rise, so that the lower steel plate continues to compress the energy storage spring to the compression height H2; then the lower actuator is operated at the set frequency to descend, so that the energy storage spring returns to the position of the initial compression height H1.

7. A fatigue test method for energy storage spring according to claim 1, characterized in that: Step 5 is as follows: Step 52: According to the calculation formula of average force Substitute the initial P1 and P2 values ​​recorded before the N fatigue cycle test to obtain the average force at the initial compression height H1. Average force at compression height H2 size; Step 53: According to the calculation formula of average force, the values ​​of P1 and P2 recorded after N fatigue cycles are input to obtain the average force at the compression height H1 after the fatigue test. Average force at compression height H2 size; Step 54: According to the relaxation rate formula The relaxation rate at each stage is calculated.

8. A fatigue test device for energy storage springs, characterized in that: Including fatigue testing machine and auxiliary equipment; The auxiliary device comprises an upper steel plate (1) and a lower steel plate (5) which are parallel to each other, and the upper steel plate (1) is fixed to the upper column of the fatigue testing machine via a connecting column (14); The upper steel plate (1) and the lower steel plate (5) are each provided with a through hole at the four corners, and four screw rods (8) are vertically inserted into the corresponding through holes of the upper steel plate (1) and the lower steel plate (5); the upper steel plate (1) and each screw rod (8) are limited by nut one (6) and nut two (7); the lower steel plate (5) and each screw rod (8) are fastened by nut three (9) and nut four (10); The upper steel plate (1) and the lower steel plate (5) have cylinders fixed on their opposite surfaces for positioning energy storage springs in the high-voltage circuit breaker to be tested.

9. The fatigue testing device for energy storage spring according to claim 7, characterized in that: The inner diameter of the cylinder is not less than the outer diameter D of the energy storage spring, and the sum of the heights of the two cylinders is less than the minimum height H2 of the spring compression fatigue.

10. The fatigue testing device for energy storage spring according to claim 7, characterized in that: The width of the upper steel plate (1) and the lower steel plate (5) is smaller than the distance between two upright posts (16) of the hydraulic servo fatigue testing machine, and the height of the screw rod (8) is smaller than the distance between the cross beam (11) and the base (17) of the fatigue testing machine.

Images