A three-direction servo vibration-based testing device for dynamic characteristics of a linear shaft joint surface of a machine tool

Abstract

The application discloses a machine tool linear shaft dynamic characteristic testing device based on three-direction servo vibration excitation, which comprises a base, a measured screw guide rail pair, a movable and liftable gantry support, a longitudinal and transverse vibration excitation device, a driving execution device and an experiment collection device. The bridge plate is installed on the measured guide rail through a sliding block, the gantry support is connected with the base through a support sliding rail, and synchronous movement with the bridge plate is realized by driving the motor. The longitudinal vibration exciter is hung on the main beam U-shaped lug, and the transverse vibration exciter is hung on the triangular support on the side of the column, so that three-direction servo vibration excitation in the normal direction, the transverse direction and the axial direction is realized. The numerical control system controls the synchronous work of the three motors, the acceleration sensor and the impedance head collect signals, the signals are transmitted to a computer for analysis and processing through a charge amplifier and a data acquisition card. The application can realize synchronous movement of the vibration exciter and the measured component, meets various dynamic characteristic testing requirements, and is suitable for stiffness and damping characteristic identification of the guide rail sliding block and the screw rolling joint surface.

Description

Technical Field

[0001] This invention relates to a testing device for obtaining dynamic characteristic parameters of a moving mating surface, belonging to the field of machine tool dynamic characteristic analysis. Background Technology

[0002] What are the closest existing technologies of the same type as the invention? What are their shortcomings or deficiencies? It is best to provide literature reviews introducing the technology. Objectively point out the problems existing in the existing technology. The machine tool manufacturing industry is the core foundation of the equipment manufacturing industry. Its processing quality, motion performance, and reliability largely depend on the dynamic characteristics of the overall machine tool structure. As more machine tools develop towards high speed, high precision, and high automation, the dynamic mating surface parameters of key kinematic pairs have become important factors affecting the overall machine performance. Modern machine tool structures are composed of various components combined according to specific functions. Different parts generally achieve contact and movement through guide pairs, rolling pairs, and support pairs. These mating surfaces are constantly subjected to changing loads and speeds during actual operation, causing their dynamic stiffness and damping to exhibit significant nonlinear characteristics. Research shows that 30%-50% of the machine tool stiffness determines the stiffness characteristics of the mating surfaces, of which the machine tool damping of the mating surfaces accounts for more than 90%, directly affecting vibration stability, trajectory accuracy, machining surface quality, and structural durability. Therefore, accurate identification of these mating surfaces has significant engineering value.

[0003] Traditional machine tool design methods, due to their inability to establish accurate dynamic models of mechanical structures, severely hinder the dynamic optimization design of mechanical structures. This is particularly true in key components such as lead screws and guideways, where the contact surface state constantly changes with motion speed, normal pressure, and lubrication conditions, making it difficult to obtain dynamic parameters through single operating conditions or fixed excitation methods. Existing measurement methods, such as modal testing with fixed excitation and partially disassembled impedance testing, cannot accurately reflect the dynamic behavior of the machine tool's mating surfaces during operation because they cannot achieve synchronous movement between the excitation point and the moving parts. Furthermore, existing testing devices typically only achieve excitation and measurement in the normal direction, failing to meet the need for multi-directional, full-condition dynamic characteristic identification of the mating surfaces. Based on this, a device is designed to identify the axial stiffness and damping characteristics of the lead screw rolling mating surface in three directions: the vertical direction (longitudinal) perpendicular to the bed mounting base, the main feed direction (axial), and the horizontal direction (transverse) perpendicular to the axial direction and parallel to the bed mounting plane, under multi-directional, multi-load, and multi-speed conditions. Summary of the Invention

[0004] The technical problem to be solved by this invention is to design a dynamic characteristic testing device for the linear axis moving joint surface of a machine tool based on three-dimensional follow-up excitation, so that it is simple and reliable to operate and realize the identification of the normal, transverse and axial stiffness and damping characteristics of the guide rail slider joint surface and the ball screw rolling joint surface.

[0005] The specific technical solution adopted by this invention to solve its technical problem is as follows:

[0006] A dynamic characteristic testing device for the moving mating surface of a machine tool linear axis based on triaxial servo excitation, the device comprising:

[0007] Base, tested lead screw guide pair (including left guide rail, right guide rail, lead screw, end cover, transmission nut, nut support, coupling), motor mounting plate, motor, bridge plate, bracket left sliding guide rail, bracket right sliding guide rail, bracket left lead screw, bracket right lead screw, guide rail connecting plate, base diagonal brace, diagonal brace connecting plate, left column sleeve, right column sleeve, inner column, connecting ear plate, top corner support rod, main beam, U-shaped lifting lug, flexible sling 1, longitudinal vibrator connector, flexible sling 2, transverse vibrator connector, vibrator, impedance head, slider, bolts.

[0008] Connections between the various parts that make up the device:

[0009] The left guide rail is bolted into the bolt holes in row a of the base, and the right guide rail is bolted into the bolt holes in row b of the base; the lead screw is installed in the central groove of the base; the end caps are respectively installed at both ends of the base; the transmission nut is fitted into the lead screw; the bridge plate is installed on the two guide rails to be measured through the slider, and is connected to the transmission nut through the nut support to complete the installation of the device under test.

[0010] The left sliding guide rail of the bracket is bolted into the bolt holes in row c of the base, and the right sliding guide rail of the bracket is bolted into the bolt holes in row d of the base; two lead screws for transmission test bracket are installed at the support holes on both sides of the base; end caps are respectively installed at both ends of the holes; and transmission nuts are fitted into the lead screws;

[0011] The left guide rail connecting plate is connected to the left sliding guide rail of the bracket via a slider; a pair of diagonal brace connecting plates are symmetrically installed on both sides of the left guide rail connecting plate, and the left guide rail connecting plate is connected to each diagonal brace connecting plate by a thread; a base diagonal brace is installed on both sides of the left column sleeve by bolts, and the two base diagonal braces are installed at the two diagonal brace connecting plates by bolts, and at the same time, an A-type support leg is fixed on each side of the left column sleeve;

[0012] The right guide rail connecting plate is connected to the right sliding guide rail of the bracket via a slider; a pair of diagonal brace connecting plates are symmetrically installed on both sides of the right guide rail connecting plate, and the right guide rail connecting plate is connected to each diagonal brace connecting plate via a thread; a base diagonal brace is installed on both sides of the right column sleeve via bolts, and the two base diagonal braces are installed at the two diagonal brace connecting plates via bolts, and at the same time, an A-type support leg is fixed on each side of the right column sleeve;

[0013] Two inner columns are respectively assembled in the left and right column sleeves, and the inner columns are connected to the column sleeves with bolts. The reserved holes on the column sleeves can be connected to the holes at different positions on the inner columns to realize the lifting function of the gantry frame. Each inner column is fitted with a connecting ear plate, and the inner column and the connecting ear plate are connected by bolts.

[0014] The main beam is installed on the upper end face of the two inner columns, and the main beam and the inner columns are connected by bolts; one end of the two top corner support rods is connected to the main beam by bolts, and the other end is connected to the two connecting lugs by bolts; the U-shaped lifting lugs slide on the main beam through pulleys to adjust the position of the vibrator; the above assembly process forms a movable and liftable gantry support device.

[0015] One end of the flexible sling 1 is suspended on the U-shaped lifting lug; the longitudinal exciter connector is suspended on the flexible sling 1; the normal exciter is installed on the longitudinal exciter connector by bolts; the impedance head is installed on the excitation end of the exciter; the above assembly process forms a longitudinal excitation device.

[0016] The right column sleeve is designed with a triangular bracket cantilever structure on the side, on which a flexible sling 2 is suspended; the transverse exciter connector is suspended on the flexible sling 2; the lateral exciter is installed on the transverse exciter connector by bolts; the above assembly process forms a transverse excitation device.

[0017] Three motors drive the lead screw and two support lead screws respectively, and the CNC system controls the three motors to work synchronously; the output shaft of the DC motor reducer is connected to the lead screw or support lead screw through a coupling to transmit power to the lead screw or support lead screw; the lead screw or support lead screw and the transmission nut cooperate to convert the motor power into translational force; the above assembly process forms the drive actuator.

[0018] The experimental data acquisition device includes a charge amplifier, a data acquisition card, and computer software.

[0019] Compared with existing technologies, the present invention has the following advantages:

[0020] This device can achieve synchronous movement between the exciter and the guide rail, and realize dynamic excitation and acceleration response signal acquisition under different motion speeds and different normal loads;

[0021] The device is designed with two types of suspension connection structures for the flexible slings and the exciter, both horizontal and vertical, to meet the excitation requirements of the device in three directions.

[0022] The device is designed with a column consisting of a column sleeve and an inner column, enabling it to be raised and lowered. Attached Figure Description

[0023] Figure 1 Top view of the test device for dynamic characteristics of the moving contact surface of the machine tool lead screw guide pair;

[0024] Figure 2 Left view of the dynamic characteristic testing device for the moving contact surface of the machine tool lead screw guide pair;

[0025] Figure 3 This is a schematic diagram of the axial vibrator measurement.

[0026] Figure 4 This is a schematic diagram of the ball screw connection for the base.

[0027] Figure 5 This is the main view of the base;

[0028] Figure 6 Top view of the base;

[0029] Figure 7 This is a schematic diagram of the longitudinal vibrator connector.

[0030] Figure 8 This is a schematic diagram of the connecting parts for a transverse vibrator.

[0031] Figure 9 Left view of the block diagram of the data acquisition, analysis and processing system;

[0032] Figure 10 This is the main view of the block diagram of the data acquisition, analysis, and processing system.

[0033] Figure 11 This is a schematic diagram of an equivalent single-degree-of-freedom system. Detailed Implementation

[0034] The present invention will be further described with reference to the accompanying drawings as specific embodiments:

[0035] A device for testing the dynamic characteristics of the moving joint surface of a machine tool linear axis based on triaxial servo excitation, such as... Figure 1 , 23. The device includes: base 1, end cover 2-1, end cover 2-2, coupling 3-1, motor mounting plate 4-1, motor 5-1, right guide rail 6, lead screw 7, left guide rail 8, bracket left sliding guide rail 9-1, bracket right sliding guide rail 9-2, bridge plate 10, connecting plate 11-1, connecting plate 11-2, connecting plate 11-3, connecting plate 11-4, base diagonal brace 12-1, base diagonal brace 12-2, base diagonal brace 12-3, base diagonal brace 12-4, guide rail connecting plate 13-1, guide rail connecting plate 13-2, end cover 2-3, end cover 2-4, coupling 3-2, motor mounting plate 4-2, motor 5-2, bracket left lead screw 14-1, nut support 15-2, and transmission nut. 16-2, End cap 2-5, End cap 2-6, Coupling 3-3, Motor mounting plate 4-3, Motor 5-3, Nut support 15-3, Transmission nut 16-3, Right lead screw of bracket 14-2, Nut support 15-1, Transmission nut 16-1, Left column sleeve 17-1, Inner column 18-1, Connecting ear plate 19-1, Top corner support rod 20-1, Main beam 21, U-shaped lifting lug 22, Right column sleeve 17-2, Inner column 18-2, Connecting ear plate 19-2, Top corner support rod 20-2, Flexible sling 1-23, Longitudinal vibrator connector 24, Vibrator 25, Flexible sling 2-26, Transverse vibrator connector 27, Impedance head 28, Slider 29, Bolt 30.

[0036] Connections between the various parts that make up the device:

[0037] The left guide rail 8 is connected to the base 1 via bolts and bolts to the a-row bolt holes of the base 1. The right guide rail 6 is connected to the base 1 via bolts and bolts to the base 1 via bolts to the b-row bolt holes of the base 1. The lead screw 7 is installed in the central groove of the base. End caps 2-1 and 2-2 are installed at both ends of the base 1. The transmission nut 16-1 is fitted into the lead screw 7. The bridge plate 10 is installed on the left guide rail 8 and the right guide rail 6 via four sliders 29, with two sliders 29 on each guide rail. The sliders 29 are connected to the transmission nut 16-1 via nut support 15-1, thus completing the installation of the device under test.

[0038] The left sliding guide rail 9-1 of the bracket is connected to the c-row bolt holes of the base 1 by twenty-five bolts 30 and installed on the base 1. The right sliding guide rail 9-2 of the bracket is connected to the d-row bolt holes of the base 1 by twenty-five bolts 36 and installed on the base 1. The left lead screw 14-1 and the right lead screw 14-2 of the bracket for synchronous transmission test are installed at the holes on both sides of the base. The end caps 2-3 and 2-4 are installed at both ends of the hole in the base 1 for installing the left lead screw 14-1 of the bracket. The transmission nut 16-2 is fitted in the left lead screw 14-1 of the bracket. The end caps 2-5 and 2-6 are installed at both ends of the hole in the base 1 for installing the right lead screw 14-2 of the bracket. The transmission nut 16-3 is fitted in the right lead screw 14-2 of the bracket.

[0039] The guide rail connecting plate 13-1 is connected to the left sliding guide rail 9-1 of the bracket via three sliders 29; the guide rail connecting plate 13-1 is symmetrically equipped with diagonal bracing connecting plates 11-1 and 11-2 on both sides, and the guide rail connecting plate 13-1 is connected to each connecting plate by thread; the left column sleeve 17-1 is connected to the base diagonal bracing 12-1 and 12-2 on both sides by bolts, and the two base diagonal bracings are connected to the two connecting plates 11-1 and 11-2 by bolts; at the same time, there is an A-type support leg on each side of the left column sleeve 17-1 for fixing.

[0040] The guide rail connecting plate 13-2 is connected to the right sliding guide rail 9-2 of the bracket via three sliders 29; the guide rail connecting plate 13-1 is symmetrically equipped with diagonal bracing connecting plates 11-3 and 11-4 on both sides, and the guide rail connecting plate 13-2 is connected to each connecting plate by thread; the right column sleeve 17-2 is connected to the base diagonal bracing 12-3 and 12-4 on both sides by bolts, and the two base diagonal bracings are connected to the two diagonal bracing connecting plates 11-3 and 11-4 by bolts; at the same time, there is an A-type support leg on each side of the right column sleeve 17-2 for fixing.

[0041] The inner column 18-1 is assembled in the left column sleeve 17-1, and the inner column 18-2 is assembled in the right column sleeve 17-2. The inner column 18 and the column sleeve 17 are connected by bolts. The reserved holes on the column sleeve 17 can be connected to the holes at different positions on the inner column 18 to realize the lifting function of the gantry frame. The inner column 18-1 is fitted with a connecting ear plate 19-1, and the inner column 18-2 is fitted with a connecting ear plate 19-2. The inner column 18 and the connecting ear plate 19 are connected by bolts.

[0042] The main beam 21 is installed on the upper end face of the two inner columns 18, and the main beam 21 and the inner columns 18-1 and 18-2 are connected by bolts; one end of the top corner support rod 20-1 and the top corner support rod 20-2 are connected to the main beam 21 by bolts, and the other end is connected to the connecting ear plate 19-1 and the connecting ear plate 19-2 by bolts; the U-shaped lifting lug 22 slides on the main beam 21 through pulleys to realize the adjustment of the position of the vibrator 25; the above assembly process forms a movable and liftable gantry support device;

[0043] One end of the flexible sling 1-23 is suspended on the U-shaped lifting lug 22; the longitudinal exciter connector 24 is suspended on the flexible sling 1-23; the normal exciter 25 is installed on the longitudinal exciter connector 24 by bolts; the impedance head 28 is installed on the excitation end of the exciter 25; the above assembly process forms a longitudinal excitation device.

[0044] The right column sleeve 17-2 is designed with a triangular bracket cantilever structure on its side, on which a flexible sling 2-26 is suspended; the transverse exciter connector 27 is suspended on the flexible sling 2-26; when lateral excitation is required, the exciter 25 is installed on the transverse exciter connector 27 by bolts; the above assembly process forms a transverse excitation device.

[0045] Motor 5-1 drives lead screw 7, motor 5-2 drives left lead screw 14-1 of the bracket, and motor 5-3 drives right lead screw 14-2 of the bracket. The CNC system controls the three motors to work synchronously. The output shaft of the DC motor reducer is connected to lead screw 7 and bracket lead screws 14-1 and 14-2 respectively through couplings 3-1, 3-2 and 3-3, transmitting power to lead screw 7 and bracket lead screws 14-1 and 14-2. Lead screw 7 and bracket lead screws 14-1 and 14-2 cooperate with transmission nuts 16-1, 16-2 and 16-3 to convert the motor power into translational force. The above assembly process forms the drive actuator.

[0046] The experimental data acquisition device includes accelerometers A1, A3, A4, and A5, impedance head A2, exciter A6, power amplifier A7, charge amplifier A8, data acquisition card A9, and computer software A10.

[0047] The method and steps for measuring the dynamic characteristics of a dynamic mating surface using this testing device are as follows:

[0048] Step 1: Vibrator suspension arrangement and height adjustment. Based on the damping direction of the dynamic mating surface to be measured, select either a transverse or longitudinal suspension scheme for the vibrator: a U-shaped lug above the support is used to suspend flexible cables for longitudinal excitation; a side triangular bracket cantilever structure is used to suspend flexible cables for transverse excitation of the bridge deck side; suspending the transverse vibrator above the support allows for excitation of the bridge deck front face along the screw axis. The vibrator height is adjusted using the gantry lifting mechanism and flexible cables to ensure the vibrator damping head is in the appropriate working position.

[0049] Step 2: Load Application and Initial Frequency Sweep. An accelerometer is positioned on the surface to be measured. Under the control of the computer output signal, excitation is applied to the bridge plate 16 in the corresponding direction. For the initial measurement, a low starting frequency and a large frequency resolution are set for frequency sweeping. The feedback response signal is collected by the accelerometer to quickly determine the approximate range of the system's resonant frequency.

[0050] Step 3: Fine-grained frequency sweep measurement. Set the starting frequency to a frequency slightly below the resonance point. First, adjust to a smaller frequency resolution and perform a fine-grained frequency sweep test on this frequency band to improve measurement efficiency and parameter identification accuracy.

[0051] Step 4: Data Processing and Parameter Extraction. Based on the equivalent single-degree-of-freedom decoupling processing program written in the measurement principle section, the acquired acceleration signals are processed. First, an equivalent single-degree-of-freedom system model of the joint is established, as shown in the schematic diagram below. Figure 11 By treating the joint as an equivalent dynamic model of a spring and a damper, the equations of motion for this equivalent system are established:

[0052]

[0053] In the formula: m is the principal mass of the system. For the equivalent stiffness coefficient of the mating surface, The equivalent damping coefficient of the mating surface. The displacement signal is obtained by processing the signal measured by the accelerometer A1 on the guide rail. The displacement signal is obtained by processing the signal measured by the accelerometer A3 on the bridge plate.

[0054] The signals measured by the sensor are subjected to Fourier transform and expressed as follows: , , Based on this derivation, the bonding surface system can be equivalent to having equivalent mass. Equivalent damping With equivalent stiffness For a single-degree-of-freedom system, its frequency response function is denoted as... :

[0055]

[0056] During the test, the signals acquired by the impedance head and sensor were conditioned by a charge amplifier and then transmitted by the data acquisition card to the host computer program for spectrum analysis to obtain the relative displacement frequency response function of the sliding guide pair. Frequency response function at the center of gravity of the bridge deck Based on the calculation principle, the obtained frequency response function is further processed, and the coefficient k is adjusted to plot the frequency response function curve of the equivalent single-degree-of-freedom system.

[0057] Based on the obtained equivalent single-degree-of-freedom system frequency response function curve, the peak resonance method is used to identify the system's natural frequencies. The equivalent stiffness is determined using the following formula:

[0058]

[0059] The system damping ratio can be obtained using the half-power bandwidth method, and its calculation formula is as follows:

[0060]

[0061] in This is the half-power bandwidth. The equivalent damping can be further identified using the following formula:

[0062]

[0063] Where k is the adjustment coefficient.

[0064] The above embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without inventive effort, that is, all modifications, equivalent substitutions, and improvements made within the spirit and principle of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A testing device for the dynamic characteristics of the moving joint surface of a machine tool linear axis based on triaxial servo excitation, characterized in that, include: The base (1) is used to install the lead screw guide pair and test bracket under test; The tested lead screw guide pair includes a left guide rail (8), a right guide rail (6), a lead screw (7), end caps (2-1, 2-2), a transmission nut (16-1), a nut support (15-1), a bridge plate (10), and a slider (29). The bridge plate (10) is installed on the left and right guide rails through the slider (29) and is connected to the transmission nut (16-1) through the nut support (15-1). The drive actuator includes a motor (5-1, 5-2, 5-3), a coupling (3-1, 3-2, 3-3), a motor mounting plate (4-1, 4-2, 4-3), and a CNC system, used to drive the lead screw (7) and the support lead screw (14-1, 14-2) to move synchronously; The movable and liftable gantry support device includes a left sliding guide rail (9-1), a right sliding guide rail (9-2), a left lead screw (14-1), a right lead screw (14-2), guide rail connecting plates (13-1, 13-2), diagonal brace connecting plates (11-1~11-4), base diagonal brace (12-1~12-4), left column sleeve (17-1), right column sleeve (17-2), inner column (18-1, 18-2), connecting ear plate (19-1, 19-2), top corner support rod (20-1, 20-2), main beam (21), and U-shaped lifting lug (22). The longitudinal excitation device includes a first flexible sling (23), a longitudinal exciter connector (24), an exciter (25), and an impedance head (28). The longitudinal exciter connector (24) is suspended on the first flexible sling (23), and the exciter (25) is mounted on it. The transverse vibration device includes a second flexible sling (26), a transverse vibrator connector (27), and a vibrator (25). The transverse vibrator connector (27) is suspended on the second flexible sling (26), and the vibrator (25) is mounted on it. The experimental data acquisition device includes an accelerometer, an impedance head, a charge amplifier, a data acquisition card, and computer software.

2. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The left guide rail (8) is bolted to the a-row bolt holes of the base (1), and the right guide rail (6) is bolted to the b-row bolt holes of the base (1); the lead screw (7) is installed in the central groove of the base, and end caps (2-1, 2-2) are installed at both ends respectively; the transmission nut (16-1) is sleeved on the lead screw (7) and connected to the bridge plate (10) through the nut support (15-1).

3. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The left sliding guide rail (9-1) of the bracket is bolted to the c-row bolt holes of the base (1), and the right sliding guide rail (9-2) of the bracket is bolted to the d-row bolt holes of the base (1); the left lead screw (14-1) and the right lead screw (14-2) of the bracket are respectively installed in the holes on both sides of the base, and end caps (2-3, 2-4, 2-5, 2-6) are respectively installed at both ends. The transmission nuts (16-2, 16-3) are respectively sleeved on the support screw and connected to the guide rail connecting plate (13-1, 13-2) through the nut support (15-2, 15-3).

4. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The guide rail connecting plate (13-1) is connected to the left sliding guide rail (9-1) of the bracket through the slider (29), and the diagonal bracing connecting plates (11-1, 11-2) are symmetrically installed on both sides; the base diagonal bracing (12-1, 12-2) is connected to both sides of the left column sleeve (17-1) by bolts, and the base diagonal bracing is installed on the diagonal bracing connecting plate by bolts; the structure of the right column sleeve (17-2) is symmetrically arranged with the left column sleeve to form the gantry frame base support structure.

5. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The inner columns (18-1, 18-2) are respectively installed in the left and right column sleeves (17-1, 17-2), connected by bolts and adjustable at different heights; the main beam (21) is installed on the upper end face of the inner column, and the top corner support rods (20-1, 20-2) connect the main beam to the connecting ear plate (19-1, 19-2); the U-shaped lifting lug (22) is slidably set on the main beam (21) for suspending the longitudinal vibration device.

6. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The right column sleeve (17-2) is provided with a triangular bracket cantilever structure on its side for suspending the second flexible sling (26), thereby realizing the arrangement of the transverse excitation device.

7. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: In the drive actuator, motor (5-1) drives lead screw (7), motor (5-2) drives left lead screw (14-1) of bracket, and motor (5-3) drives right lead screw (14-2) of bracket; the CNC system controls the three motors to work synchronously to ensure that the vibrator and the tested component move synchronously.

8. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: In the experimental acquisition device, the acceleration sensor is arranged on the bridge plate (10) and the guide rail, the impedance head (28) is installed on the excitation end of the exciter (25), and the signal is conditioned by the charge amplifier and then transmitted to the computer by the data acquisition card for analysis and processing.

9. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The device is used to identify the stiffness and damping characteristics of the guide rail slider joint surface in the normal direction, the transverse direction, and the lead screw rolling joint surface in the axial direction. The exciter can realize three-dimensional follow-up excitation.

10. The dynamic characteristic testing device for the moving joint surface of a machine tool linear axis based on triaxial servo excitation according to claim 1, characterized in that: The method and steps for measuring the dynamic characteristics of a dynamic mating surface using this testing device are as follows: Step 1: Vibrator suspension arrangement and height adjustment; Based on the damping direction of the dynamic mating surface to be measured, select the transverse or longitudinal suspension scheme of the vibrator: U-shaped lugs on the upper part of the bracket are used to suspend flexible slings to achieve longitudinal excitation; the side triangular bracket cantilever structure is used to suspend flexible slings to achieve transverse excitation of the bridge deck side; the transverse vibrator is suspended above the bracket to excite the front face of the bridge deck along the axial direction of the lead screw; the height of the vibrator is adjusted by the gantry lifting mechanism and the flexible slings to ensure that the damping head of the vibrator is in a suitable working position; Step 2: Load application and initial frequency sweep; accelerometers are placed on the surface to be measured, and under the control of the computer output signal, the bridge plate 16 is excited in the corresponding direction; during the first measurement, a low starting frequency and a large frequency resolution are set for frequency sweep, and the feedback response signal is collected by the accelerometers to quickly determine the approximate range of the system's resonant frequency. Step 3: Fine frequency sweep measurement; Set the starting frequency at a frequency slightly below the resonance point, first adjust to a smaller frequency resolution, and perform a fine frequency sweep test on this frequency band to improve measurement efficiency and parameter identification accuracy; Step 4: Data Processing and Parameter Extraction; Based on the equivalent single-degree-of-freedom decoupling processing program written in the measurement principle section, the collected acceleration signals are processed; First, an equivalent single-degree-of-freedom system model of the joint is established, and the joint is equivalent to a dynamic model of a spring and a damper, and the motion equations of this equivalent system are established: ； In the formula: m is the principal mass of the system. For the equivalent stiffness coefficient of the mating surface, The equivalent damping coefficient of the mating surface. The displacement signal is obtained by processing the signal measured by the accelerometer A1 on the guide rail. The displacement signal is obtained by processing the signal measured by the accelerometer A3 on the bridge plate; The signals measured by the sensor are subjected to Fourier transform and expressed as follows: , , ; Based on this derivation, the bonding surface system is equivalent to having equivalent mass. Equivalent damping With equivalent stiffness For a single-degree-of-freedom system, its frequency response function is denoted as... : ； During the test, the signals acquired by the impedance head and sensor were conditioned by a charge amplifier and then transmitted by the data acquisition card to the host computer program for spectrum analysis to obtain the relative displacement frequency response function of the sliding guide pair. Frequency response function at the center of gravity of the bridge deck ; Based on the calculation principle, the obtained frequency response function is further processed and the coefficient k is adjusted to plot the frequency response function curve of the equivalent single-degree-of-freedom system. Based on the obtained equivalent single-degree-of-freedom system frequency response function curve, the peak resonance method is used to identify the system's natural frequencies. The equivalent stiffness is determined using the following formula: ； The system damping ratio can be obtained using the half-power bandwidth method, and its calculation formula is as follows: ； in Half-power bandwidth; Identify equivalent damping using the following formula: ； Where k is the adjustment coefficient.

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