An accelerated testing platform and method for spindle accuracy retention based on multi-variable load loading

Abstract

This invention provides an accelerated testing platform and method for spindle precision retention based on multi-load loading, including a spindle and drive unit, a temperature load loading unit, a vibration load loading unit, and a simulated cutting load loading unit. It also provides an accelerated testing method for spindle precision retention that considers the accelerated degradation of spindle precision under the coupled effects of multiple loads such as force, heat, and vibration. This method significantly shortens the testing cycle while achieving spindle precision retention testing, and simultaneously solves problems such as missing information on the precision degradation process and imperfect quantitative evaluation methods for precision retention. It is of great significance for meeting the urgent need for rapid testing of precision spindle precision retention and for filling the gaps in the field of spindle precision retention testing.

Description

Technical Field

[0001] This invention belongs to the field of testing, specifically relating to an accelerated testing platform and method for spindle accuracy retention based on multi-variable load loading. Background Technology

[0002] High-end CNC machine tools are fundamental and strategic equipment for the nation, widely used in key national sectors such as aerospace, defense, and automobile manufacturing. They are crucial strategic equipment for ensuring national defense security and the national economy. The machine tool spindle is a vital functional component of high-end CNC machine tools, and its ability to maintain precision during service is one of the key performance indicators, largely determining the actual machining accuracy of the CNC machine tool.

[0003] Currently, spindle performance testing primarily focuses on reliability testing, employing axial and radial loading devices to perform reliability loading tests on the spindle. While spindle reliability levels have significantly improved with advancements in reliability technology, issues such as short accuracy retention time and poor accuracy retention capability are still commonly observed during service. However, current spindle accuracy retention testing capabilities are relatively weak, facing challenges such as high testing difficulty and long testing cycles. Furthermore, the lack of relevant national standards for theoretical guidance and the imperfect testing equipment and methods represent a long-standing technical problem for the industry.

[0004] Spindle accuracy is affected by external loads such as cutting force, ambient temperature and humidity, and forced vibration. The contact, wear, and lubrication conditions of key interfaces such as bearings vary significantly under different loads, resulting in large differences in the rate of spindle accuracy degradation. Currently, spindle accuracy retention testing mostly employs on-site tracking testing or simulated cutting force or torque loading methods, which still suffer from problems such as excessively long testing cycles and lack of information on the accuracy degradation process. Furthermore, it lacks quantitative evaluation of spindle accuracy retention, severely restricting spindle manufacturers from understanding the performance of product accuracy retention and optimizing product iteration. For example, Chinese Patent Publication No. CN202110358740.2 discloses a method and apparatus for simulating transient dynamic loads on a high-speed electric spindle, capable of applying simulated cutting loads to test spindle reliability. However, this apparatus and method primarily focus on spindle reliability testing, neglecting the spindle accuracy retention degradation state and failing to achieve a quantitative evaluation of spindle accuracy retention capability. Meanwhile, this device can only apply working loads simulating cutting forces, and cannot apply environmental loads such as temperature and humidity, or external vibration loads simulating service conditions, thereby changing the interface friction and lubrication state of the spindle bearings, etc. This causes the spindle accuracy to degrade at a relatively normal rate, failing to solve the problem of long accuracy retention test cycles. For example, the mechanical spindle reliability test bench disclosed in Chinese Patent Publication No. CN201620348825.7 uses a servo spindle motor to load the spindle axially, allowing for spindle reliability testing and evaluation. However, this device also only focuses on spindle reliability and can only conduct tests related to the normal rate of spindle degradation. Furthermore, Chinese Patent Publication Nos. CN201110313367.5, CN202010756077.7, CN202120676545.X, and other patents, as well as documents such as "Quantitative Evaluation of Accuracy Retention and Analysis of Accuracy Degradation Mechanism" and "Research on Accuracy Degradation and Retention Assessment of Electric Spindle Rotation," also commonly suffer from the above problems. Therefore, there is an urgent need to propose an accelerated testing platform and related testing methods for spindle accuracy retention to solve the problem of accelerated testing of spindle accuracy retention. Summary of the Invention

[0005] Based on the accelerated degradation mechanism of spindle precision caused by changes in bearing interface contact, friction and lubrication under the combined action of simulated cutting force, ambient temperature and humidity and external forced vibration, this invention proposes an accelerated testing method and testing platform for spindle precision retention based on multi-load loading.

[0006] The technical solution of this invention:

[0007] An accelerated testing platform for spindle accuracy retention based on multi-variable load loading is provided. The accelerated testing platform for spindle accuracy retention includes a spindle and drive unit, a temperature and humidity load loading unit, a vibration load loading unit, and a simulated cutting load loading unit.

[0008] The spindle and drive unit include a tested spindle 1-1, a custom-made probe 1-2, a V-shaped base 1-3, a drive motor 1-4, a transmission belt 1-5, a vibration sensor 1-6, and a temperature sensor 1-7. The V-shaped base 1-3 is mounted on the extended platform 3-3 of the vibration loading unit. The tested spindle 1-1 is mounted on the V-shaped base 1-3 and positioned relative to the extended platform 3-3 via the V-shaped base 1-3. The base of the drive motor 1-4 is fixed to the extended platform 3-3, and the drive motor 1-4 is connected to the rear end of the tested spindle 1-1 via the transmission belt 1-5. The custom-made probe 1-2 is fixed inside the tapered hole at the front end of the tested spindle 1-1. The vibration sensor 1-6 and the temperature sensor 1-7 are both magnetically attached to the tested spindle 1-1. The middle section of the custom-made probe 1-2 is a stepped shaft.

[0009] The temperature and humidity load loading unit includes a storage panel 2-1, a storage door 2-2, a unit 2-3, and a temperature and humidity loading environment 2-4. The storage panel 2-1 is installed on the foundation, the storage door 2-2 is installed in conjunction with the storage panel 2-1, and the unit 2-3 is installed on the foundation and contacts the side of the storage panel 2-1. Ultimately, the temperature and humidity inside the temperature and humidity loading environment 2-4 are changed through the heater, cooler, humidifier, and dryer inside the unit 2-3.

[0010] The vibration loading unit 3 includes a vibration generator 3-1, an extended platform heat insulation pad 3-2, an extended platform 3-3, and a support base 3-4. The rotation axis of the vibration generator 3-1 is coaxial with the central axis of symmetry of the support base 3-4. The vibration generator 3-1 is fixedly mounted on the support base 3-4, and the extended platform 3-3 is fixed to the upper part of the vibration generator 3-1. The extended platform heat insulation pad 3-2 is laid on the extended platform 3-3 in the vibration loading unit 3.

[0011] The simulated cutting loading unit includes an axial loading force generating device 4-1, a radial loading force generating device 4-2, a rotational accuracy measuring device 4-3, an axial loading support bracket 4-4, a radial loading support bracket 4-5, an axial load loading frame 4-6, a support frame 4-7, a one-way thrust ball bearing with a spherical seat ring 4-8, a deep groove ball bearing 4-9, an inner retaining ring of the deep groove ball bearing 4-10, an outer retaining ring of the deep groove ball bearing 4-11, and a lifting slide 4-12. Among them, the one-way thrust ball bearing 4-8 with a spherical seat and the deep groove ball bearing 4-9 are installed and positioned on the custom inspection bar 1-2. The deep groove ball bearing 4-9 is installed in the middle section of the stepped shaft of the custom inspection bar 1-2. The inner ring is supported by the inner retaining ring 4-10 of the deep groove ball bearing installed in the middle section of the stepped shaft of the custom inspection bar 1-2, and the outer ring is supported by the support frame 4-7 and the outer retaining ring 4-11 of the deep groove ball bearing installed in the stepped shaft of the custom inspection bar 1-2. The one-way thrust ball bearing 4-8 with a spherical seat is installed in the front section of the stepped shaft of the custom inspection bar 1-2 and fixed to the end face. The other end is pressed by the axial load loading frame 4-6 installed in the custom inspection bar 1-2. The axial load support bracket 4-4 and the radial load support bracket 4-5 are fixed on the lifting slide 4-12. The axial load force generating device 4-1 and the radial load force generating device 4-1 are also present. The tail section of the device 4-2 is fixedly connected to the axial loading support bracket 4-4 and the radial loading support bracket 4-5 respectively; the rotational accuracy measuring device 4-3 includes two eddy current displacement sensors and one sensor bracket, which are arranged between the two axial loading support brackets 4-4 and are close to but not in contact with the customized test bar 1-2; the front end of the radial loading force generating device 4-2 passes through the side hole of the support bracket 4-7 and contacts the deep groove ball bearing 4-9; the front end of the axial loading force generating device 4-1 contacts the axial load loading bracket 4-6; the axial loading force generating device 4-1 and the radial loading force generating device 4-2 are located on the same horizontal plane as the axis of the measured spindle 1-1, and their front ends are in contact with the surfaces of the axial load loading bracket 4-6 and the deep groove ball bearing 4-9 respectively, so as to realize the loading of axial and radial forces on the measured spindle 1-1.

[0012] The method for accelerating spindle accuracy retention testing using the aforementioned accelerated testing platform based on multi-variable load loading includes the following steps:

[0013] Step 1: Obtain the configuration structure of the spindle under test 1-1 and the target operating conditions information.

[0014] Step 2: Based on the information in Step 1, formulate an accelerated degradation scheme for multi-load loading based on the principle of unifying the load coefficients of the design load and service environment of the spindle under test 1-1, and then determine the magnitude of the simulated dynamic cutting load, external vibration, temperature and humidity load for different spindles under test 1-1.

[0015] Step 3: Assemble the customized test bar 1-2 into the tapered hole at the front end of the spindle 1-1 under test, and hoist the spindle 1-1 under test to the extended platform 3-3 of the testing device and position it through the V-shaped base 1-3. Connect the drive motor 1-4 to the spindle 1-1 under test through the transmission belt 1-5, start the drive motor 1-4, and gradually increase the speed of the spindle 1-1 under test to 70-80% of the maximum speed, then reduce the speed to 40-50% of the maximum speed and run it for a period of time to complete the preheating of the spindle 1-1 under test.

[0016] Step 4: Adjust the position of the lifting slide 4-12 of the simulated cutting loading unit so that the first part of the axial loading force generating device 4-1 and the radial loading force generating device 4-2 respectively contact the loading point of the customized test bar 1-2, and debug various sensors of the test platform.

[0017] Step 5: Without applying simulated cutting loads and environmental loads such as temperature, humidity, and vibration, start the spindle under test 1-1 and gradually increase it to 70-80% of the maximum speed of the spindle under test 1-1 and hold it there. Use the rotational accuracy measuring device 4-3 to complete the initial rotational accuracy test of the spindle under test 1-1 in an unloaded state.

[0018] Step 6: According to the accelerated degradation scheme, simulated cutting force, temperature and humidity, vibration and other loads are applied simultaneously to accelerate the degradation of the accuracy of the measured spindle 1-1 under the coupling effect of multiple loads.

[0019] Step 7: Calculate the load distribution of the spindle bearing under the initial load, establish a performance degradation model of the spindle system dynamics and bearing damage coupling under the multi-load coupling action, as shown in Equation (1), calculate the dynamic response state of the rotor-bearing system within the cycle, and calculate the load distribution under the current damage elastic modulus and wear depth, then calculate the wear accumulation and damage expansion degree within the cycle, and determine whether the cycle number specified by the cycle block has been reached. If the cycle number has not been reached, the load distribution under the current damage elastic modulus and wear depth is recalculated. If the cycle number has been reached, the spindle rotation accuracy is tested and recorded, and the wear damage degree and dynamic response state are calculated. It is determined whether the damage and wear threshold dynamic instability state has been reached. If the judgment threshold has not been reached, the load distribution under the current damage elastic modulus and wear depth is recalculated and subsequent steps are carried out. If the judgment threshold has been reached, the bearing performance degradation degree or life cycle is calculated, and the calculation process ends.

[0020]

[0021]

[0022] In the formula, M represents the mass matrix of the spindle system; {q} represents the displacement vector of the spindle system; C(t) represents the damping matrix of the spindle system; G is the gyroscope matrix; K(t) represents the stiffness matrix of the spindle system; F c (t) represents the external cutting load; a and b are competing degradation parameters; D represents the cumulative degradation of the spindle bearing; D N (t) represents the cumulative degradation degree of spindle bearing damage after N cycles; Δτ(t) is the octahedral shear stress; σ r For material parameters; D t k represents the amount of damage and degradation. w Here, σ(x,y) is the wear coefficient, σ(x,y) is the contact stress, S(x,y) is the sliding distance, and H is the material hardness. Stiffness, contact stress, and wear coefficient are all affected by the combined effects of temperature and humidity, vibration load, and cutting load.

[0023] Step 8: When the test time is reached or the accuracy degradation of the tested spindle 1-1 reaches the preset upper limit, turn off all external load loading modules and perform a rotation accuracy test on the tested spindle 1-1 under no-load conditions.

[0024] Step 9: Summarize all test data and calculate the accuracy retention of the measured spindle 1-1 at all rotational accuracy measurement times. The calculation steps are as follows:

[0025]

[0026]

[0027] Where, δ i,w (t n ) represents the rotational accuracy δ of the measured spindle 1-1. i In t n Precision retention at specific times, ρ i For conditional functions To ensure rotational accuracy at time t n Mean of error variation within the range, For failure accuracy, The mean of the error variation (Equation 4), This represents the original precision.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention proposes an accelerated testing platform and method for spindle precision retention based on multi-element load loading. During high-speed spindle operation, simulated cutting loads, temperature and humidity loads, and vibration loads are applied simultaneously, causing rapid changes in the contact, friction, and lubrication states of the spindle bearing system. This accelerates the rate of precision degradation of the spindle system, significantly shortening the spindle precision retention testing cycle and solving the "blind spots and pain points" in existing testing methods and platforms for spindle precision retention testing.

[0030] 2. This invention proposes an accelerated testing platform and method for spindle accuracy retention based on multi-variable load loading, which realizes the tracking and identification of accuracy throughout the entire process of spindle accuracy degradation, and solves the "blind spot" problem of missing accuracy degradation process state when using existing testing methods and platforms for spindle accuracy retention testing.

[0031] 3. This invention proposes an accelerated testing method for spindle accuracy retention based on multi-element load loading. By calculating the spindle accuracy retention rate, it solves the "blind spot" problem that existing testing methods cannot quantitatively evaluate the spindle accuracy retention capability. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the platform.

[0033] Figure 2 This is a schematic diagram of the platform's internal structure.

[0034] Figure 3 This is a schematic diagram of the structure of the simulated cutting loading unit.

[0035] Figure 4 Cross-sectional view of the simulated cutting loading unit structure

[0036] Figure 5 Schematic diagram of load bearing arrangement

[0037] Figure 6 Schematic diagram of reassembly accuracy testing system

[0038] Figure 7 View of the lifting slide

[0039] Figure 8 Accelerated degradation test procedure for spindle accuracy retention under multi-load coupling

[0040] Figure 9 This is a schematic diagram of the accuracy retention index, which is used to evaluate accuracy retention. Detailed Implementation

[0041] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and technical solutions.

[0042] In this embodiment, the tested spindle 1-1 is a belt-driven mechanical spindle with a central diameter of approximately 150mm. A custom-made BT40 gauge bar 1-2 is mounted at the front. The V-shaped base 1-3 has a clamping angle of 90°, with its lowest point 50mm from the table surface. The straight-line distance between the spindle 1-1's axis and the motor's axis is 500mm. The motor 1-4 is an AC servo spindle motor, approximately 315*365mm in size. The vibration sensor 1-6 is a triaxial accelerometer. The temperature sensor 1-7 is an infrared temperature sensor. The temperature and humidity loading environment 2-4 measures 2*2*1.8m, with a temperature range of 0–40℃, a maximum temperature change rate of 1℃ / min, and a humidity range of 20–98%RH. The vibration generator 3-1 provides a vibration source with a vertical frequency range of 5–500Hz and transmits the vibration to the spindle 1-1 via a 1.2*1.2m extended table 3-3. The axial loading force generating device 4… -1. Radial loading force generating devices 4-2 both use piezoelectric actuators with a maximum stroke of 200μm, maximum thrust >2000N, maximum loading frequency >800Hz, and a length of 163mm; The rotational accuracy measurement system is configured with one eddy current sensor each at the radial and axial positions of the support, and the spindle rotational accuracy is tested according to "GBT17421.7-2016 General Rules for Machine Tool Inspection Part 6: Geometric Accuracy of Rotation Axis"; Axial loading support... The brackets 4-4, 4-5, 4-6, 4-7, 4-10, and 4-11 of the deep groove ball bearing inner retaining ring and outer retaining ring are all made of 7-series aluminum alloy, with a support height of 105mm. The single-direction thrust ball bearing 4-8 with a spherical seat ring is SKF53202. The deep groove ball bearing 4-9 is SFK6308. The lifting slide 4-12 is an electric scissor lift with a maximum stroke of 300mm.

[0043] The specific process of accelerated testing of spindle accuracy retention is as follows: First, obtain the basic information of the spindle under test, including spindle configuration and operating conditions. Based on the basic information of the spindle, formulate an accelerated degradation scheme with multi-element load loading that does not change the conventional failure mechanism. Determine the simulated dynamic cutting load (amplitude and frequency are determined according to typical milling conditions), external vibration (amplitude and frequency are determined by the amount of vibration transmitted from the column of the same machine tool to the spindle box), temperature (20℃ as the initial temperature, increasing by 10℃ every 20 minutes of testing, reaching 40℃ and then decreasing by 10℃ every 20 minutes of testing, repeating the cycle until the test ends), and humidity (40% as the initial humidity, increasing by 10% every 20 minutes of testing, reaching 80% and then decreasing by 80% every 20 minutes of testing, repeating the cycle until the test ends).

[0044] The spindle under test 1-1 is hoisted onto the V-shaped base 1-3 and fixed in place. The spindle under test 1-1 is then connected to the output shaft of the drive motor 1-4 via the transmission belt 1-5. The custom-made inspection bar 1-2 is installed into the tapered hole at the front end of the spindle under test 1-1. The spindle is started and the speed is gradually increased to the maximum, then the speed is reduced to 50% of the maximum speed and run for 20 minutes to complete the spindle preheating.

[0045] Install the lifting slide 4-12 to a position 105mm below the axis of the custom inspection bar 1-2. Then, sequentially install the inner retaining ring 4-10 of the deep groove ball bearing, the support frame 4-7, the deep groove ball bearing 4-9, and the outer retaining ring 4-11 of the deep groove ball bearing to the middle stepped shaft position of the custom inspection bar 1-2. Next, sequentially install the one-way thrust ball bearing 4-8 with a spherical seat ring and the axial load loading frame 4-6 to the front stepped shaft position of the custom inspection bar 1-2. Align the axial load support bracket 4-4 with the axial load loading frame 4-6 and secure it to the lifting slide 4-12 platform using bottom screws. Move the radial load support bracket 4-5 until it aligns with the side hole of the support frame 4-7 and secure it to the lifting slide 4-12 platform using bottom screws. Place the axial load generating device 4-1 on the axial load support bracket 4-4 and adjust its position so that its front end contacts the axial load loading frame 4-6. Place the radial loading force generator 4-2 on the radial loading support bracket 4-5, and adjust its position so that its front end passes through the through hole in the side wall of the support bracket 4-7 and fits against the surface of the deep groove ball bearing 4-9. Arrange the rotational accuracy testing system 4-3 between the two axial loading support brackets 4-4.

[0046] Without applying an external load, start the spindle under test 1-1 and gradually increase it to 80% of the maximum spindle speed and hold it thereafter. At the same time, complete the initial no-load accuracy test of the spindle through the rotational accuracy test system 4-3.

[0047] According to the accelerated degradation scheme, the loads of the temperature and humidity loading unit, vibration loading unit, and simulated cutting load loading unit are applied synchronously according to the test plan.

[0048] The load distribution of the spindle bearing under the initial multi-element load is calculated. Based on the bearing performance degradation model of the spindle system dynamics coupled with bearing wear / damage under the coupling of multi-element loads, the dynamic response state of the rotor-bearing system within the cycle is calculated. The load distribution under the current damage elastic modulus and wear depth is calculated. Then, the wear accumulation and damage expansion degree within the cycle are calculated to determine whether the specified number of cycles has been reached. If the number of cycles has been reached, the spindle rotation accuracy is tested and recorded. At the same time, the wear damage degree and dynamic response state are calculated to determine whether the damage, wear threshold, and active mechanical instability state have been reached. It is determined whether to record it as the bearing performance degradation degree or the final state of the life cycle. If not, the dynamic response state of the rotor-bearing system within the cycle is recalculated and subsequent steps are carried out.

[0049] Finally, all test data are summarized, and the spindle accuracy retention at all rotation accuracy measurement times is calculated according to formula (3) to quantitatively evaluate the spindle accuracy retention.

Claims

1. An accelerated testing platform for spindle accuracy retention based on multi-variable load loading, characterized in that, The spindle accuracy retention accelerated testing platform includes a spindle and drive unit, a temperature and humidity load loading unit, a vibration load loading unit, and a simulated cutting load loading unit; The spindle and drive unit include the spindle under test (1-1), a custom-made probe (1-2), a V-shaped base (1-3), a drive motor (1-4), a transmission belt (1-5), a vibration sensor (1-6), and a temperature sensor (1-7). The V-shaped base (1-3) is mounted on the extended platform (3-3) of the vibration loading unit, and the spindle under test (1-1) is mounted on the V-shaped base (1-3), achieving connection with the extended platform through the V-shaped base (1-3). The display stand (3-3) is positioned, the base of the drive motor (1-4) is fixed to the extended stand (3-3), the drive motor (1-4) is connected to the rear end of the main shaft under test (1-1) through the transmission belt (1-5), and the customized inspection bar (1-2) is fixed in the tapered hole at the front end of the main shaft under test (1-1); the vibration sensor (1-6) and the temperature sensor (1-7) are all magnetically attracted to the main shaft under test (1-1); the middle section of the customized inspection bar (1-2) is in the form of a stepped shaft; The temperature and humidity load loading unit includes a storage panel (2-1), a storage door (2-2), a unit (2-3), and a temperature and humidity loading environment (2-4). The storage panel (2-1) is installed on the foundation, the storage door (2-2) is installed in conjunction with the storage panel (2-1), and the unit (2-3) is installed on the foundation and contacts the side of the storage panel (2-1). Finally, the temperature and humidity inside the temperature and humidity loading environment (2-4) are changed through the heater, cooler, humidifier, and dryer inside the unit (2-3). The vibration loading unit (3) includes a vibration generator (3-1), an extended platform heat insulation pad (3-2), an extended platform (3-3), and a support base (3-4); wherein, the rotation axis of the vibration generator (3-1) is coaxial with the central axis of symmetry of the support base (3-4); and the vibration generator (3-1) is fixedly installed on the support base (3-4), and the extended platform (3-3) is fixed on the upper part of the vibration generator (3-1); the extended platform heat insulation pad (3-2) is laid on the extended platform (3-3) in the vibration loading unit (3); The simulated cutting loading unit includes an axial loading force generating device (4-1), a radial loading force generating device (4-2), a rotational accuracy measuring device (4-3), an axial loading support bracket (4-4), a radial loading support bracket (4-5), an axial load loading frame (4-6), a support frame (4-7), a one-way thrust ball bearing with a spherical race (4-8), a deep groove ball bearing (4-9), an inner retaining ring of the deep groove ball bearing (4-10), an outer retaining ring of the deep groove ball bearing (4-11), and a lifting slide (4-12); wherein, the one-way thrust ball bearing with a spherical race... (4-8) and deep groove ball bearing (4-9) are mounted and positioned on the custom-made inspection bar (1-2). The deep groove ball bearing (4-9) is installed in the middle section of the stepped shaft of the custom-made inspection bar (1-2). The inner ring is supported by the inner retaining ring (4-10) of the deep groove ball bearing installed in the middle section of the stepped shaft of the custom-made inspection bar (1-2). The outer ring is supported by the support frame (4-7) and the outer retaining ring (4-11) of the deep groove ball bearing installed in the stepped shaft of the custom-made inspection bar (1-2). The one-way thrust ball bearing (4-8) with a spherical seat ring is installed on the front section of the stepped shaft of the custom-made inspection bar (1-2) and fixed to the end face. The other end is mounted by... The axial load loading bracket (4-6) of the customized inspection bar (1-2) is pressed together; the axial load support bracket (4-4) and the radial load support bracket (4-5) are fixed on the lifting slide (4-12); the tail parts of the axial load force generating device (4-1) and the radial load force generating device (4-2) are respectively fixedly connected to the axial load support bracket (4-4) and the radial load support bracket (4-5); the rotation accuracy measuring device (4-3) includes two eddy current displacement sensors and one sensor bracket, arranged between the two axial load support brackets (4-4), and connected to the customized inspection bar. (1-2) Close to but not in contact; the front end of the radial loading force generating device (4-2) passes through the side hole of the support frame (4-7) and contacts the deep groove ball bearing (4-9); the front end of the axial loading force generating device (4-1) contacts the axial load loading frame (4-6); the axial loading force generating device (4-1) and the radial loading force generating device (4-2) are located on the same horizontal plane as the axis of the measured spindle (1-1), and their front ends are in contact with the surfaces of the axial load loading frame (4-6) and the deep groove ball bearing (4-9) respectively, so as to realize the loading of axial and radial forces on the measured spindle (1-1).

2. A method for accelerating spindle accuracy retention testing using a spindle accuracy retention acceleration testing platform based on multi-element load loading as described in claim 1, characterized in that, Includes the following steps: Step 1: Obtain the configuration structure and target operating conditions information of the spindle under test (1-1); Step 2: Based on the information from Step 1, formulate an accelerated degradation scheme for multi-variable load loading based on the principle of unifying load factors such as the design load and service environment of the spindle under test (1-1), and then determine the magnitude of the simulated dynamic cutting load, external vibration, temperature and humidity load for different spindles under test (1-1). Step 3: Assemble the customized test bar (1-2) into the tapered hole at the front end of the spindle under test (1-1), and hoist the spindle under test (1-1) to the extended platform (3-3) of the testing device and position it through the V-shaped base (1-3). Connect the drive motor (1-4) to the spindle under test (1-1) through the transmission belt (1-5), start the drive motor (1-4), and gradually increase the speed of the spindle under test (1-1) to 70-80% of the maximum speed, then reduce the speed to 40-50% of the maximum speed and run it for a period of time to complete the preheating of the spindle under test (1-1). Step 4: Adjust the position of the lifting slide (4-12) of the simulated cutting loading unit so that the first part of the axial loading force generating device (4-1) and the radial loading force generating device (4-2) respectively contact the loading point of the customized test bar (1-2), and debug various sensors of the test platform; Step 5: Start the spindle under test (1-1) without applying simulated cutting loads and environmental loads such as temperature, humidity and vibration, and gradually increase the speed to 70-80% of the maximum speed of the spindle under test (1-1) and hold it there. Use the rotational accuracy measuring device (4-3) to complete the initial rotational accuracy test of the spindle under test (1-1) under no-load conditions. Step 6: According to the accelerated degradation scheme, simulated cutting force, temperature and humidity, and vibration load are applied simultaneously to accelerate the degradation of the accuracy of the spindle under test (1-1) under the coupling effect of multiple loads; Step 7: Calculate the load distribution of the spindle bearing under the initial load, establish a performance degradation model of the spindle system dynamics and bearing damage coupling under the multi-load coupling action, as shown in Equation (1), calculate the dynamic response state of the rotor-bearing system within the cycle, and calculate the load distribution under the current damage elastic modulus and wear depth, then calculate the wear accumulation and damage expansion degree within the cycle, and determine whether the cycle number specified by the cycle block has been reached. If the cycle number has not been reached, the load distribution under the current damage elastic modulus and wear depth is recalculated. If the cycle number has been reached, the spindle rotation accuracy is tested and recorded, and the wear damage degree and dynamic response state are calculated. It is determined whether the damage and wear threshold dynamic mechanical instability state has been reached. If the judgment threshold has not been reached, the load distribution under the current damage elastic modulus and wear depth is recalculated and subsequent steps are carried out. If the judgment threshold has been reached, the bearing performance degradation degree or life cycle is calculated, and the calculation process ends. In the formula, M represents the mass matrix of the spindle system; {q} represents the displacement vector of the spindle system; C(t) represents the damping matrix of the spindle system; G is the gyroscope matrix; K(t) represents the stiffness matrix of the spindle system; F c (t) represents the external cutting load; a and b are competing degradation parameters; D represents the cumulative degradation of the spindle bearing; D N (t) represents the cumulative degradation degree of spindle bearing damage after N cycles; Δτ(t) is the octahedral shear stress; σ r For material parameters; D t k represents the amount of damage and degradation. w σ(x,y) is the wear coefficient, S(x,y) is the contact stress, H(x,y) is the sliding distance, and H is the material hardness. Among them, stiffness, contact stress, and wear coefficient are all affected by the combined effects of temperature and humidity, vibration load, and cutting load. Step 8: When the test time is reached or the accuracy degradation of the spindle under test (1-1) reaches the preset upper limit, turn off all external load loading modules and perform a rotation accuracy test on the spindle under test (1-1) under no-load conditions. Step 9: Summarize all test data and calculate the accuracy retention of the spindle (1-1) at all rotational accuracy measurement times. The calculation steps are as follows: Where, δ i,w (t n ) represents the rotational accuracy δ of the measured spindle (1-1). i In t n Precision retention at specific times, ρ i For conditional functions To ensure rotational accuracy at time t n Mean of error variation within the range, For failure accuracy, The mean of the error variation This represents the original precision.

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