Lubricating state monitoring device for rotary sliding interface

Abstract

The invention discloses a lubricating state monitoring device for a rotary sliding interface. The lubricating state monitoring device comprises a rotary circular truncated cone module, an insulating objective table, a conductive slip ring, a lower sample, an upper sample, an insulating sample clamp, a conductive screw and nut set, a terminal wire, a sleeve, a three-dimensional force sensor and an LCR digital bridge. The sleeve, the three-dimensional force sensor and the rotary circular truncated cone module are fixedly arranged at corresponding positions of the friction-wear testing machine, and are connected with a power line, a data acquisition card and a program control board card. And the insulating objective table and the conductive slip ring are sequentially arranged at the corresponding positions of the rotary circular truncated cone module. After an upper sample is placed in an inner cavity of the insulation sample clamp and clamped, a corresponding conductive screw and nut set is installed, a wire end is led out from the bottom of a nut through a terminal wire, and the insulation sample clamp with a wire is placed in a sleeve and clamped. The upper computer drives the three-dimensional force sensor to move to a target position to apply a load, and the LCR digital bridge monitors electrical characteristic parameters of an overall circuit and uploads the electrical characteristic parameters to the upper computer for storage and visualization.

Description

Technical Field

[0001] The invention relates to a lubrication state monitoring device for a rotary sliding interface, and relates to the technical field of friction coefficient measurement. Background Art

[0002] Mechanical components such as sliders, guide rails, and sliding bearings are widely used in various industrial manufacturing situations. Most of their failure problems are caused by tribological factors such as wear failure caused by insufficient lubrication. During the operation of such mechanical components, the relatively sliding contact pairs are often in a closed space. It is difficult to directly monitor the lubrication status between the contact pairs except for indirect means such as monitoring the friction torque. By taking advantage of the fast response and easy control of electrical signals, inputting a determined disturbance signal to the metal contact pair and analyzing its corresponding electrical characteristics can help directly monitor the real-time lubrication status of the metal contact pair. However, for rotating mechanical components such as sliding bearings, it is necessary to consider the circuit winding problem caused by the rotational motion, and the existence of other metal components except the contact pair will introduce a large amount of redundant impedance, which will weaken the correlation between the measured electrical characteristic parameters and the circuit components of the contact area. Therefore, it is necessary to design a lubrication status monitoring device for the rotating sliding interface.

[0003] The invention discloses a lubrication state monitoring device for a rotating sliding interface. The device is based on a unidirectional uniform speed pure sliding friction test, simulates the sliding condition of a contact pair of a real mechanical component, collects tangential force and normal force vector data in real time with the help of a three-dimensional force sensor to calculate the friction coefficient of the contact area; uses a conductive slip ring to solve the winding problem of a rotating truncated table, designs an insulating test stage and an insulating sample fixture to reduce redundant capacitive reactance, uses an LCR digital bridge to input a disturbance signal to the contact pair, measures the time-varying characteristics of the admittance (impedance) of the contact area, and analyzes the real-time lubrication state in combination with the change of the friction coefficient. Summary of the invention

[0004] The purpose of the present invention is to design a lubrication state monitoring device for a rotary sliding interface to achieve synchronous measurement of the friction coefficient and the electrical characteristics of the lubrication state of the rotary sliding contact area. The present invention will be described by taking a sample under a disk and a sample on a sphere as examples, wherein the sample clamping method involved is only for the sample shapes listed, but is not limited thereto.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The lubrication state monitoring device consists of a rotating truncated table module 1, an insulating stage 2, a conductive slip ring 3, a lower sample 4, an upper sample 5, an insulating sample fixture 6 (including an insulating collar 7, an insulating base 8, a plastic screw 9, and a plastic nut 10), a conductive screw and nut group 11, a terminal wire 12, a sleeve 13, a three-dimensional force sensor 14, and an LCR digital bridge 15.

[0007] The rotating truncated table module 1 is bolted to the corresponding hole position of the friction and wear testing machine, and connected to the driving power line and the program control board; the sleeve 13 is bolted to the bottom of the three-dimensional force sensor 14, and the three-dimensional force sensor 14 is bolted to the corresponding hole position of the friction and wear testing machine, and connected to the driving power line and the data acquisition board; the insulating stage 2 is bolted and fixed to the corresponding hole position of the metal truncated table on the rotating truncated table module 1, and its side is provided with a non-slip groove that cooperates with the fixing screw of the rotor end of the conductive slip ring 3, and the specific fixing height of the fixing screw is not limited to avoid additional normal load on the rotating truncated table module 1; the conductive slip ring 3 is placed on the external bracket of the rotating truncated table module 1, and the circumferential non-slip sheet is connected and fixed to the rotating truncated table module 1 to prevent the stator end from sliding, and the fixing screws at four places on the rotor end are in contact with the non-slip grooves of the insulating stage 2, and the length will simultaneously ensure the centering of the conductive slip ring 3 and the synchronous movement of the rotor end and the insulating stage 2; the lower sample 4 is provided with a central and an eccentric hole position, which is connected to the insulating The concentric threaded holes and the eccentric anti-rotation threaded holes on the top surface of the stage 2 correspond to each other, and the corresponding screws are used to fix the lower sample 4 on the insulating stage 2; the upper sample 5 is placed in the insulating collar 7 of the insulating sample fixture 6, and the top of the upper sample 5 is pressed and fixed with an insulating base 8 embedded with a plastic nut 9, and two plastic screws 10 are used to tighten the insulating collar 7 and the insulating base 8 to fix the upper sample 5 without rotating; threaded holes are opened around the top of the insulating stage 2, and a conductive screw nut group 11 is screwed in until the tail end of the screw is in close contact with the side of the lower sample 4; the insulating sample fixture 6 is provided with an axial clearance hole, in which the conductive screw nut group 11 can be placed and bolted with the plastic nut 8 in the insulating sample fixture, and the conductive screw nut group 11 is screwed in until the tail end of the screw is in close contact with the upper sample 5; the terminal wire 12 is wound around the nut near each conductive screw, and the conductive nut is screwed to the nut to press the terminal wire 12, to ensure a sufficiently large conductive contact area to reduce the shrinkage resistance. Insert the insulating sample fixture 6 with wire into the sleeve 13 according to the corresponding position of the locating pin of the sleeve 13, and tighten the clamping screw on the side of the sleeve 13; the LCR digital bridge 15 test clamp is respectively connected to the stator end outlet of the conductive slip ring 3 and the insulating sample fixture 6 outlet, and all wiring methods need to reduce the line capacitance as much as possible; after completing the above work, turn on the LCR digital bridge 15, perform zero calibration after sufficient warm-up, and adjust it to the required LCR parameter test function on the host computer; the host computer software drives the three-dimensional force sensor 14 to drive the insulating sample fixture 6 to locate the test position, and move it to the corresponding eccentricity of the upper sample 4, the host computer sets the preload and drives the rotating table module 1 to work to start the rotational sliding friction test. During the test, the three-dimensional force sensor 14 can collect the tangential and normal forces of the insulating sample fixture 6 in real time, and calculate the real-time friction coefficient of the contact area between the upper sample 5 and the lower sample 4; at the same time, the LCR digital bridge 15 collects the electrical characteristics of the total circuit (conductive slip ring 3-lower sample 4-upper sample 5-several conductive screw and nut combinations 11-several terminal wires 12) in real time and uploads them to the host computer.

[0008] The rotating frustum module 1 is connected to the corresponding hole position of the friction and wear testing machine through bolts, and is connected to the driving power line and the program control board to drive the sample to rotate.

[0009] The insulating stage 2 is connected to the corresponding holes of the metal truncated table on the rotating truncated table module 1 by bolts, and its end surface is provided with a central threaded hole and an eccentric threaded hole, which are matched with the two openings of the lower sample 4. Four anti-slip grooves are provided on its side surface to match the rotor fixing bolts of the conductive slip ring 3.

[0010] The conductive slip ring 3 is divided into an inner ring rotor end and an outer ring stator end, which is placed on the external bracket of the rotating truncated table module 1. The circumferential anti-slip sheet is connected and fixed to the external bracket to prevent the stator end from sliding. The rotor end is in contact with the anti-slip groove of the insulating platform 2 by four fixing screws, and its length will ensure that the conductive slip ring 3 is aligned and the rotor end moves synchronously with the insulating platform 2.

[0011] The end surface of the lower sample 4 is provided with a central through hole and an eccentric through hole, and is fixed to the end surface of the insulating carrier 2 by bolting.

[0012] The upper sample 5 is a ready-made sample with a customized size.

[0013] The insulating sample fixture 6 comprises an insulating collar 7, an insulating base 8, a plastic screw 9, and a plastic nut 10. The insulating collar 7 is provided with an internal cavity and two positioning through holes that can be closely fitted with the upper sample 5. The large end surface of the insulating base 8 is provided with a rectangular groove and two threaded holes for placing the plastic nut 9. The side surface is provided with a wiring groove and a positioning hole that cooperates with the sleeve positioning pin. The central axis is provided with a through hole for placing the conductive screw nut group 11. The plastic nut 10 cooperates with the cavity of the insulating base 8 to fix the upper sample 5. The plastic screw 9 tightens the insulating collar 7 and the insulating base 8 to clamp the upper sample 5. At the same time, the plastic nut 10 will cooperate with the conductive screw bolt to ensure that the upper sample and the conductive screw are in contact and energized. The overall combination effect is shown in the following figure (a).

[0014] The combination of the upper sample 5, the insulating sample fixture 6 and the conductive screw nut group 11 can greatly reduce unnecessary factors such as redundant air impedance caused by excess metal contact, because only the conductive screw is in conductive contact with the upper sample 5, and the rest are insulating materials. Moreover, the conductive components are all arranged on the same normal axis, which can maximize the regularization of the equivalent circuit of the combination. As shown in Figure (b), according to the capacitance calculation formula, the capacitance between a pair of separated conductors is determined by the area of ​​the two conductors facing each other, so the equivalent capacitance of the combination is determined by the diameter of the upper sample 5 or the cross-sectional area of ​​the conductive screw nut. At this time, the upper red dotted box area is equivalent to the contact shrinkage resistance between the conductive nut and the upper part of the sample and the composite air plastic non-polar dielectric capacitance in parallel, which is usually a fixed value after a single disassembly and assembly; the lower red dotted box area is equivalent to the lubricant-plastic mixed capacitance outside the contact area and the contact shrinkage resistance and lubricant capacitance in parallel after the series sample resistance is connected. When the space between the insulating sample fixture 6 and the lower sample 4 is fully filled with lubricant, the mixed capacitance outside the contact area remains almost unchanged, so the variables can be almost controlled in the contact area, making the obtained data more targeted.

[0015] The conductive screw and nut set 11 are all ready-made standard parts, and the material is pure copper to ensure sufficiently low resistivity.

[0016] The terminal wires 12 are all ready-made parts, and copper core wires and terminals are selected to ensure sufficiently low resistivity.

[0017] The bottom of the sleeve 13 is provided with a hole and a positioning pin for inserting the insulating sample fixture 6, the side is provided with a bolt tightening device to clamp the insulating sample fixture 6, and the top is provided with a positioning hole corresponding to the threaded hole of the three-dimensional force sensor 14.

[0018] The three-dimensional force sensor 14 is connected to the moving guide rail of the friction and wear testing machine through bolts to measure and collect the tangential and normal force parameters of the entire device.

[0019] The LCR digital bridge 15 is a common electrical measuring instrument on the market.

[0020] Furthermore, the contact zone friction coefficient and lubrication state monitoring method comprises the following steps:

[0021] The rotating frustum table module 1 is fixed to the corresponding position of the friction and wear testing machine by bolt connection, and the power cord and program control board are connected.

[0022] After the sleeve 13 is fixed to the corresponding hole position of the three-dimensional force sensor 14 by bolt connection, it is connected to the moving guide rail of the friction and wear testing machine by bolt connection, and the power line and the information acquisition board are connected.

[0023] The insulating loading platform 2 is fixed to the corresponding hole position of the metal truncated table of the rotating truncated table module 1 by bolt connection.

[0024] Place the conductive slip ring 3 on the external bracket of the rotating truncated table module 1, rotate the positioning screws at the rotor end until all the positioning screws are in contact with the side anti-slip grooves of the insulating platform 2 to ensure that the position of the rotor end is aligned and the rotational movement is stable, and then connect and fix the circumferential anti-slip sheet at the stator end to the external bracket of the rotating truncated table module 1 by bolt connection.

[0025] Place the lower sample 4 on the top end surface of the insulating stage 2, align the center hole and the eccentric hole, and screw the positioning screw to ensure that the lower sample 4 and the insulating stage 2 are relatively stationary. Screw the conductive screw nut set 11 into the threaded hole on the side of the insulating stage 2 until the tail of the screw is in full contact with the side of the lower sample 4, place the terminal wire 12 at the bottom of the nut and tighten the conductive nut to maximize the conductive area, and the other end of the terminal wire 12 is connected to the rotor end of the conductive slip ring.

[0026] After placing the upper sample 5 in the inner cavity of the insulating collar 7, it is combined with the insulating base 8 after the plastic nut 9 is placed, and the combination is tightened with the plastic screw 10 to clamp the upper sample 5. The conductive screw nut group 11 is placed in the hollow hole of the central axis of the insulating base 8 and bolted to the plastic nut 10 until the tail end of the conductive screw contacts the upper sample 5, and then the terminal wire 12 is placed at the bottom of the nut and the conductive nut is tightened to maximize the conductive area.

[0027] The wire-carrying insulating sample fixture 6 is placed into the corresponding hole of the sleeve 13 and matched with the positioning pin, and the tightening device on the side of the sleeve is tightened to clamp the insulating sample fixture 6.

[0028] The LCR digital bridge 15 test clamp is connected to the stator outgoing wire of the conductive slip ring 3 and the outgoing wire of the insulating sample fixture 6 respectively. All wiring methods need to reduce the line capacitance as much as possible.

[0029] After completing the above work, start the LCR digital bridge 15, perform zero calibration after sufficient warm-up, and adjust to the required LCR parameter test function on the host computer; the host computer software drives the three-dimensional force sensor 14 to drive the insulating sample fixture 6 to locate the test position, and move to the corresponding eccentric position of the upper sample 4. The host computer sets the preload and drives the rotating table module 1 to start the rotation sliding friction test. During the test, the three-dimensional force sensor 14 can collect the tangential and normal forces on the insulating sample fixture 6 in real time, and calculate the real-time friction coefficient of the contact area between the upper sample 5 and the lower sample 4; at the same time, the LCR digital bridge 15 collects the electrical characteristics of the total circuit (conductive slip ring 3-lower sample 4-upper sample 5-several conductive screw nut combinations 11-several terminal wires 12) in real time and uploads them to the host computer.

[0030] The present invention adopts the above technical solution, which has the following advantages:

[0031] The lubrication state monitoring device for a rotating sliding interface disclosed in the present invention has a simple structure and is easy to assemble and disassemble. The conductive winding problem is solved by customizing a conductive slip ring 3 that matches the size of the rotating truncated table module of the friction and wear testing machine. The conductive transmission of the precise precious metal sliding contact inside the conductive slip ring ensures the stability of the test signal at both ends of the contact area. The insulating sample fixture 6 can greatly reduce unnecessary factors such as redundant air impedance caused by the excess metal contact of the upper sample 5, and the conductive components are all arranged on the same normal axis, which can maximize the regularization of the equivalent circuit of the combination. The overall circuit equivalent of the insulating sample fixture 6-upper sample 5-conductive screw nut group 11 can be maximized. At the same time, since the overall test device is an open structure, it is easy to embed other test modules and has strong compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the overall assembly drawing.

[0033] Figure 2 It is an exploded view (except LCR digital bridge). Figure 3 This is a schematic diagram of the sample installation. Figure 4 It is a coaxial identification diagram of the upper specimen installation. DETAILED DESCRIPTION

[0034] The following description is made by taking the upper sample 5 of the CCr15 bearing steel ball and the lower sample 4 of the 9Cr18 bearing steel disc as examples, but the present invention is not limited to this.

[0035] When conducting tribological tests, the device is used as follows:

[0036] Step 1: The sleeve 13 is fixed at the corresponding position of the three-dimensional force sensor 14 by bolt connection, and the rotating table module 1 and the three-dimensional force sensor 14 are fixed at the specified positions of the friction and wear testing machine respectively, and the power supply, data acquisition card and program control board are connected.

[0037] Step 2: Bolt and fix the insulating stage 2 on the metal stage of the rotating stage module 1, place the conductive slip ring 3 on the external bracket of the rotating stage module 1, and make the rotating slip ring rotor positioning screw contact and cooperate with the anti-slip groove on the side of the insulating stage 2. After confirming the centering, connect and fix the circumferential anti-slip plate on the stator end of the slip ring to the rotating stage module 1.

[0038] Step 3: Place the lower sample 4 on the top end face of the insulating platform 2 according to the positioning hole position and screw on the positioning screw, then screw the conductive screw nut set 11 into the threaded hole on the side of the insulating platform 2 until the tail of the screw contacts the side of the lower sample 4, wrap the terminal wire 12 around the bottom of the nut and tighten the conductive nut to the nut, and the other end of the terminal wire 12 is connected to the rotor end of the conductive slip ring 3.

[0039] Step 4: Place the upper sample 5 into the inner cavity of the insulating collar 7, insert the plastic nut 9 into the insulating base 8, connect the assembly and bolt it with the plastic screw 10 to ensure that the upper sample 5 is clamped. Place the conductive screw nut set 11 into the hollow hole on the central axis of the insulating base 8 and bolt it with the plastic nut 9. After the tail end of the screw contacts the upper sample 5, wrap the terminal wire 12 around the bottom of the nut and tighten the conductive nut to the nut.

[0040] Step 5: Place the wired insulating sample fixture 6 into the corresponding hole of the sleeve 13, and match it with the positioning pin, and tighten the side tightening device of the sleeve 13 to clamp the insulating sample fixture 6. Fix the outgoing wire of the insulating sample fixture 6 and the outgoing wire of the stator end of the conductive slip ring 3 in a suitable area using a specific method, and the wiring method needs to reduce the inter-wire capacitance as much as possible.

[0041] Step 6: Start the LCR digital bridge 15 to fully warm up and adjust to zero, then start the host computer and the friction and wear tester. Connect the LCR digital bridge 15 test clamp to the stator outgoing wire of the conductive slip ring 3 and the outgoing wire of the insulating sample fixture 6 respectively.

[0042] Step 7: Add an appropriate amount of lubricant to the preset motion trajectory of the lower sample 4, adjust the LCR digital bridge 15 to the required measurement function, and the host computer drives the three-dimensional force sensor 14 and its additional accessories to move to an eccentric position of the lower sample 4 according to the set eccentric radius. The host computer sets a preload, drives the guide rail of the friction and wear testing machine to move, and moves the three-dimensional force sensor 14 and its additional accessories downward to apply a normal load to a place on the lower sample 4. After loading is completed, the rotating table module 1 is driven to operate to drive the insulating stage 2 and its additional accessories to rotate, so that the upper sample 5 performs a circular sliding motion relative to the lower sample 4. During the movement, the three-dimensional force sensor 14 can collect the total force on the contact point of the upper sample 5. According to the measured values ​​of the tangential and normal forces changing with time, the values ​​of the friction coefficient of the contact area changing with time can be obtained. During this period, the LCR digital bridge 15 continuously collects the overall circuit electrical characteristic parameters such as the impedance modulus and the phase angle changing with time and uploads them to the host computer software for visualization.

[0043] Step 8: After the test is completed, the three-dimensional force sensor 14 and its additional accessories are driven to move upward, and the insulating sample fixture 6, the upper sample 5 and the lower sample 4 are taken out in sequence, and the data are exported and post-processed.

[0044] Step 9: To proceed to the next set of tests, repeat steps 3 to 8.

[0045] The lubrication state monitoring device for a rotating sliding interface designed by the present invention has a simple structure and is easy to disassemble and assemble. It not only ensures the stability of the conductive performance of the device by means of a customized conductive slip ring, but also greatly reduces the redundant impedance by the insulating design of the sample fixture, thereby enhancing the pertinence of the electrical characteristic measurement data. The present invention is mainly used for the friction coefficient measurement of the rotating sliding friction test, and the electrical characteristic monitoring test of the lubrication state of the friction contact area. The scheme is as follows: a rotating truncated table module, an insulating stage, a conductive slip ring, a lower sample, an upper sample, an insulating sample fixture (including an insulating collar, an insulating base, a plastic screw, a plastic nut), a conductive screw nut group, a terminal wire, a sleeve, a three-dimensional force sensor, and an LCR digital bridge. The sleeve, the three-dimensional force sensor and the rotating truncated table module are fixed to the corresponding positions of the friction and wear testing machine, and the power cord, the data acquisition card and the program control board are connected. The insulating stage and the conductive slip ring are installed in the corresponding positions of the rotating truncated table module in turn. After completing the position alignment and follow-up performance verification of the conductive slip ring, the lower sample and the corresponding conductive screw nut group are installed, and the conductive screw nut group and the conductive slip ring rotor end outlet are connected with the terminal wire. After placing the upper sample into the internal cavity of the insulating sample fixture and clamping it, install the corresponding conductive screw nut group, use the terminal wire to lead the wire end at the bottom of the nut, place the wired insulating sample fixture into the sleeve and clamp it. After completing the above work, start all equipment for hot machine zeroing, add an appropriate amount of lubricant to the lower sample, and connect the LCR digital bridge test clamp to the stator end of the conductive slip ring and the outlet wire in the sleeve respectively. The host computer drives the three-dimensional force sensor to move to the target position to apply the load, and drives the rotating table module to rotate at the set speed to start the friction coefficient measurement test. The three-dimensional force sensor measures the total force of the upper sample in the sliding contact area and uploads it to the host computer to calculate the friction coefficient. The LCR digital bridge monitors the overall circuit electrical characteristic parameters and uploads them to the host computer for storage and visualization.

[0046] In summary, the lubrication state monitoring device and test process for a rotary sliding interface described in the present invention can be simply and effectively used in various rotary sliding friction test research occasions. The customized high-performance conductive slip ring 3 supports rotary modules of various sizes to ensure the stability and reliability of the conductive performance. The design of the insulating sample fixture 6 can greatly reduce the redundant impedance problem caused by the complex metal contact between the metal fixture and the metal sample, which provides great convenience for studying the electrical characteristics of tribological behavior.

Claims

1. A lubrication status monitoring device for a rotating sliding interface, characterized in that: It comprises a rotating truncated table module (1), an insulating stage (2), a conductive slip ring (3), a lower sample (4), an upper sample (5), an insulating sample fixture (6), a conductive screw-nut assembly (11), a terminal wire (12), a sleeve (13), a three-dimensional force sensor (14) and an LCR digital bridge (15); the insulating sample fixture (6) comprises an insulating collar (7), an insulating base (8), a plastic screw (9) and a plastic nut (10); The rotating truncated table module (1) is bolted to the corresponding hole position of the friction and wear testing machine, and is connected to the driving power line and the program control board; the sleeve (13) is bolted to the bottom of the three-dimensional force sensor (14); the three-dimensional force sensor (14) is bolted to the corresponding hole position of the friction and wear testing machine, and is connected to the driving power line and the data acquisition board. The insulating stage (2) is bolted to the corresponding hole position of the metal truncated table on the rotating truncated table module (1) and is bolted and fixed. The side surface of the insulating stage (2) is provided with a non-slip groove that cooperates with the fixing screw of the rotor end of the conductive slip ring (3), and the specific fixing height of the fixing screw is not limited to avoid the additional normal load of the rotating truncated table module; the conductive slip ring (3) is placed on the external bracket of the rotating truncated table module (1), and the circumferential non-slip sheet is connected to the rotating truncated table module (1). The truncated cone module (1) is connected and fixed to prevent the stator end from sliding, and the four fixing screws at the rotor end are in contact with the anti-slip grooves of the insulating stage (2). The length of the fixing screws will ensure the centering of the conductive slip ring (3) and the synchronous movement of the rotor end and the insulating stage (2). The lower sample (4) is provided with a center hole and an eccentric hole, which correspond to the centering threaded hole and the eccentric anti-rotation threaded hole on the top surface of the insulating stage (2). The lower sample (4) is fixed on the insulating stage (2) using corresponding screws. The upper sample (5) is placed in the insulating collar (7) of the insulating sample fixture (6), and the top of the upper sample (5) is pressed and fixed with an insulating base (8) embedded with a plastic nut (10). Two plastic screws (9) connect the insulating collar (7) to the insulating stage (2). The insulating sample holder (6) is provided with an axial clearance hole, in which the conductive screw nut assembly (11) is placed and bolted with the plastic nut (10) in the insulating sample holder (6), and the conductive screw nut assembly (11) is screwed in until the tail end of the screw is in close contact with the side of the lower sample (4); the insulating sample holder (6) is provided with a axial clearance hole, in which the conductive screw nut assembly (11) is placed and bolted with the plastic nut (10) in the insulating sample holder (6), and the conductive screw nut assembly (11) is screwed in until the tail end of the screw is in close contact with the upper sample (5); the terminal wire (12) is wound around the nut of each conductive screw, and the conductive nut is screwed to the nut to press the terminal wire (12) tightly, so as to ensure a sufficiently large conductive contact area to reduce the shrinkage resistance; the insulating sample holder (6) is provided with an axial clearance hole, in which the conductive screw nut assembly (11) is placed and bolted with the plastic nut (10) in the insulating sample holder (6), and the conductive screw nut assembly (11) is screwed in until the tail end of the screw is in close contact with the upper sample (5); the terminal wire (12) is wound around the nut of each conductive screw, and the conductive nut is screwed to the nut to press the terminal wire (12) tightly, so as to ensure a sufficiently large conductive contact area to reduce the shrinkage resistance; The conductive screw nut group (11) at the table is connected to the rotor end of the conductive slip ring (3) with the corresponding terminal wire (12), and the terminal wire (12) of the insulating sample fixture (6) is connected to the LCR digital bridge (15) test clamp; the insulating sample fixture (6) with wire is inserted into the sleeve (13) according to the corresponding position of the positioning pin of the sleeve (13), and the clamping screw on the side of the sleeve (13) is tightened; the LCR digital bridge (15) test clamp is respectively connected to the stator end outlet of the conductive slip ring (3) and the insulating sample fixture (6) outlet, and all wiring methods reduce the line capacitance; the LCR digital bridge (15) is started, and zero calibration is performed after sufficient warm-up, and the upper computer is adjusted to the required LCR parameter test function;The upper computer software drives the three-dimensional force sensor (14) to drive the insulating sample fixture (6) to locate the test position and move it to the corresponding eccentric position of the upper sample (5). The upper computer sets the preload and drives the rotating table module (1) to start the rotating sliding friction test.

2. A lubrication state monitoring device for a rotary sliding interface according to claim 1, characterized in that: During the test, the three-dimensional force sensor (14) collects the tangential and normal forces of the insulating sample fixture (6) in real time, and uploads them to the host computer to calculate the real-time friction coefficient of the contact area between the upper sample (5) and the lower sample (4); at the same time, the LCR digital bridge (15) collects the electrical characteristics of the total circuit, the conductive slip ring (3), the lower sample (4), the upper sample (5), the plurality of conductive screw nut assemblies (11), and the plurality of terminal wires (12) in real time, and uploads them to the host computer.

3. The lubrication state monitoring device for a rotary sliding interface according to claim 1, characterized in that: The material selection and structural design of the insulating sample fixture (6) reduce the redundant metal impedance; the conductive components are all arranged on the same normal axis, so that the overall circuit equivalence of the insulating sample fixture (6), the upper sample (5), and the conductive screw nut combination (11) is regularized to the greatest extent, and the change of the measured electrical characteristic parameters is controlled in the contact area and its vicinity.

4. The lubrication state monitoring device for a rotary sliding interface according to claim 1, characterized in that: With the help of the test environment provided by the friction and wear testing machine, the tangential and normal force data measured by the three-dimensional force sensor (14) are used to calculate the change of the friction coefficient of the sliding contact area over time, and the electrical characteristics collected by the host computer from the LCR digital bridge (15) over time are combined to perform correlation analysis.

5. The lubrication state monitoring device for a rotary sliding interface according to claim 1 comprises the following steps: The rotating truncated table module (1) is fixed to the corresponding position of the friction and wear testing machine by means of bolt connection, and a power line and a program control board are connected; After the sleeve (13) is fixed to the corresponding surface of the three-dimensional force sensor (14) by bolt connection, it is connected together with the movable guide rail of the friction and wear testing machine, and the power line and the information acquisition board are connected; The insulating loading platform (2) is fixed to the corresponding hole position of the metal truncated table of the rotating truncated table module (1) by means of bolt connection; Place the conductive slip ring (3) on the external bracket of the rotating truncated table module (1), rotate the positioning screws at the rotor end until all the positioning screws are in contact with the side anti-slip grooves of the insulating platform (2), ensure the position of the rotor end is aligned and the rotation movement is stable, and then connect and fix the circumferential anti-slip sheet at the stator end to the external bracket of the rotating truncated table module (1) by bolt connection; The lower sample (4) is placed on the top end surface of the insulating platform (2), and after aligning the center hole and the eccentric hole, the positioning screw is screwed on to ensure that the lower sample (4) and the insulating platform (2) are relatively stationary; the conductive screw nut assembly (11) is screwed into the threaded hole on the side of the insulating platform (2) until the tail of the screw is in full contact with the side of the lower sample (4), and the terminal wire (12) is placed at the bottom of the nut and the conductive nut is tightened to increase the conductive area; After placing the upper sample (5) in the inner cavity of the insulating sleeve (7), the upper sample (5) is assembled with the insulating base (8) after the plastic nut 9 is inserted and the assembly is tightened with the plastic screw (9) to clamp the upper sample (5); the conductive screw nut assembly (11) is placed in the hollow hole of the central axis of the insulating base (8) and bolted with the plastic nut (10) until the tail end of the conductive screw contacts the upper sample (5), and then the terminal wire (12) is placed at the bottom end of the nut and the conductive nut is tightened to increase the conductive area; Place the wire-carrying insulating sample fixture (6) into the corresponding hole of the sleeve (13), match it with the positioning pin, and tighten the side tightening device of the sleeve (13) to clamp the insulating sample fixture (6); The LCR digital bridge (15) test clamp is connected to the stator outgoing wire of the conductive slip ring (3) and the outgoing wire of the insulating sample fixture (6) respectively; The LCR digital bridge (15) is turned on and started, and the machine is warmed up for zero calibration, and the upper computer is adjusted to the required LCR parameter test function; the upper computer software drives the three-dimensional force sensor (14) to drive the insulating sample fixture (6) to locate the test position, and move it to the corresponding eccentric position of the lower sample (4), and the upper computer sets the preload and drives the rotating table module (1) to start the rotating sliding friction test; during the test, the three-dimensional force sensor (14) collects the tangential and normal forces of the insulating sample fixture (6) in real time, and calculates the real-time friction coefficient of the contact area between the upper sample (5) and the lower sample (4); at the same time, the LCR digital bridge (15) collects the electrical characteristics of the total circuit in real time and uploads them to the upper computer.

Images