A friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion

Abstract

The invention provides a friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion, comprising a support module, four preloading modules, a static specimen module and a dynamic specimen module; the support module comprises four right-angle mounting frames, four normal positioning brackets, two transverse mounting frames, two longitudinal mounting frames, two normal adapting brackets and a normal mounting frame; the preloading module comprises two universal ball bearings, a universal ball bearing base, a tangential force sensor, a preloading piston, a preloading sleeve and a large spring plunger; the static specimen module comprises a normal force sensor, a static specimen, a static specimen mounting base, a static specimen mounting top cover, a piezoelectric actuator, a piezoelectric actuator base, a normal connection adapter, a normal loading piston, a normal loading sleeve and a small spring plunger; the dynamic specimen module comprises a dynamic specimen, two acceleration sensors, a dynamic specimen mounting base, a dynamic specimen motion platform, two linear guide rail assemblies, two vibrators, a cross linear guide rail, an I-shaped bracket, two three-way positioning fixtures and two laser displacement sensors.

Description

Technical Field

[0001] The invention belongs to the technical field of research on friction and wear interface characteristics, and specifically relates to a friction and wear experimental device capable of realizing time-varying normal pressure and two-dimensional relative motion trajectory of an interface. Background Art

[0002] Dry friction and wear phenomena are widely present in mechanical systems with assembled structures. There are a large number of close contact interfaces in the connection structures (such as bolts, flanges, etc.) of the mechanical system, the support and transmission structures (such as gears, bearings, etc.), and some damping structures (shoulder, blade crown, edge plate damper, etc.). These contact surfaces will form a small relative slip due to the vibration generated by the mechanical system during operation, and wear will occur on the contact interface under long-term working conditions.

[0003] Friction and wear at the contact interface will cause changes in the mechanical properties of the contact surface, such as changes in the surface friction coefficient, contact stiffness, and contact surface profile. Previous studies have shown that even changes in the mechanical properties of the contact interface caused by slight friction and wear will have a drastic impact on the dynamic characteristics of the system, further affecting the integrity and reliability of the mechanical system. Therefore, it is necessary to conduct in-depth research on the degradation mechanism of the contact interface characteristics caused by friction and wear, so as to accurately predict the evolution law of the system's dynamic characteristics.

[0004] However, in the current research on the evolution mechanism of mechanical properties of contact interfaces, one-dimensional wear tests of friction pairs under constant positive pressure are generally used to construct and verify the wear model. One of the characteristics of this type of test is that the normal pressure is assumed to be a constant and the relative motion of the friction pair is one-dimensional, which simplifies the test and is a preliminary study on the evolution of interface characteristics under friction and wear. However, under service conditions, due to the certain angle between the contact surface and the direction of structural vibration, the normal pressure acting on the contact interface is often not a constant but a periodic change; and the relative motion trajectory of the contact surface is generally not a straight line, but a two-dimensional motion within the interface, such as the blade crown and the damping ring. This leads to the load state of the specimen in the existing interface wear test often deviating from the actual situation, which in turn makes it difficult for the verified wear model to accurately describe the evolution of the contact interface of the assembled structure under service conditions.

[0005] In summary, a friction and wear experimental device that can realize time-varying normal pressure and two-dimensional relative motion trajectory of the interface is urgently needed to study the mechanical characteristics and evolution laws of the friction interface in the power mechanical system. Summary of the invention

[0006] In view of the limitations of existing friction and wear experimental devices, the purpose of the present invention is to provide a wear experimental device that can realize time-varying positive pressure and two-dimensional relative motion trajectory of the friction interface, which can be used to reveal the interface hysteresis characteristics and its evolution law under service conditions and calibrate the wear model.

[0007] The technical solution adopted by the present invention is: specifically comprising a support module, four pre-loading modules, a static specimen module and a dynamic specimen module.

[0008] The support module includes four right-angle mounting frames, four normal positioning brackets, two transverse mounting frames, two longitudinal mounting frames, two normal adapter brackets, and a normal mounting frame; the characteristics are: the right-angle mounting frame is fixedly connected to the workbench by bolts; the normal positioning bracket is installed on the rectangular column of the right-angle mounting frame from the side; the transverse mounting frame is fixed to the normal positioning bracket by bolts; the longitudinal mounting frame is connected to the transverse mounting frame by bolts; the normal adapter bracket is fixedly connected to the right-angle mounting frame by bolts; the normal mounting frame is fixedly connected to the normal adapter bracket by bolts.

[0009] The preloading module comprises two universal ball bearings, a universal ball bearing base, a tangential force sensor, a preloading piston, a preloading sleeve and a large spring plunger; the characteristics are as follows: the universal ball shaft is in point contact with the static specimen mounting base and is connected to the universal ball bearing base through its own screw; the tangential force sensor is fixedly connected to the universal ball bearing base and the preloading piston through its own screw; the preloading piston is installed in the preloading sleeve; the preloading sleeve is adapted to the mounting groove of the transverse mounting frame or the longitudinal mounting frame and is fixedly connected by bolts; the preloading sleeve is threadedly connected to the large spring plunger; every two transverse (longitudinal) preloading modules form a group, and the two groups of preloading modules with orthogonal force transmission paths work together, so that the static specimen mounting base only retains the normal translational degree of freedom; the friction force of the contact interface between the static specimen and the dynamic specimen in the transverse and longitudinal directions is measured by the tangential force sensors of the paired preloading modules.

[0010] The static specimen module comprises a normal force sensor, a static specimen, a static specimen mounting base, a static specimen mounting top cover, a piezoelectric actuator, a piezoelectric actuator base, a normal connection adapter, a normal loading piston, a normal loading sleeve, and a small spring plunger; the static specimen is fixedly connected to the static specimen mounting base through a square mounting hole and bolts; the static specimen mounting top cover is fixedly connected to the static specimen mounting base through bolts; the piezoelectric actuator ball head is in tight contact with the static specimen mounting top cover; the piezoelectric actuator base and the piezoelectric actuator are in tight contact with each other. The actuator mounting end is fixedly connected by a mounting groove and bolts; the normal connection adapter is fixedly connected to the piezoelectric actuator base by bolts; the normal force sensor is fixedly connected to the normal connection adapter and the normal loading piston by its own screw; the normal loading piston is installed in the normal loading sleeve; the normal loading sleeve is fixedly connected to the normal mounting frame by mounting groove bolts; the normal loading sleeve is fixedly connected to the small spring plunger by threads; the static specimen mounting base is constrained by four preloading modules and does not move in the lateral and longitudinal directions.

[0011] The dynamic specimen module includes a dynamic specimen, two acceleration sensors, a dynamic specimen mounting base, a dynamic specimen motion platform, two linear guide assemblies, two vibrators, cross linear guides, an I-shaped bracket, two three-way positioning fixtures, and two laser displacement sensors; the characteristics are as follows: the vibrator, the I-shaped bracket and the three-way positioning fixture are all fixedly connected to the workbench by bolts; a cross linear guide is used to connect the I-shaped bracket and the dynamic specimen motion platform; the two sides of the dynamic specimen motion platform are connected to the top rod of the vibrator by a linear guide assembly; the dynamic specimen is fixedly connected to the dynamic specimen mounting base by square mounting holes and bolts; the dynamic specimen mounting base is fixedly connected to the dynamic specimen motion platform by bolts; the two acceleration sensors are tightly attached to the two orthogonal sides of the dynamic specimen; and the two laser displacement sensors are fixedly connected to the three-way positioning fixture by bolts.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) The present invention can provide a periodic time-varying normal positive pressure through a piezoelectric actuator to accurately reproduce the mechanical load of the interface under service conditions;

[0014] (2) The present invention can apply a two-dimensional relative displacement load to the contact interface through two orthogonally arranged electromagnetic push rod actuators, accurately simulating the displacement load of the interface under service conditions;

[0015] (3) The present invention realizes accurate measurement of displacement and acceleration of micro-slip of two-dimensional friction and wear test pieces;

[0016] (4) The present invention realizes reliable constraint on the two-dimensional friction and wear test piece, ensures the transmission path of the load in the experimental device, and enables the force sensor to effectively and accurately measure the force condition of the two-dimensional friction and wear test piece;

[0017] (5) The two-dimensional friction and wear test pieces in the present invention have simple structures and are all detachable, which is convenient for replacement and measurement during the experiment;

[0018] (6) The support modules in the present invention are designed with multiple movable slots, which ensures that the test piece has high adjustability during installation; the support structure is detachable and replaceable as a whole, and the installation is simple and the operability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is an overall schematic diagram of the friction and wear experimental device of the present invention.

[0020] Figure 2 It is a horizontal schematic diagram of different structural modules of the friction and wear experimental device described in the present invention.

[0021] Figure 3 It is a longitudinal schematic diagram of different structural modules of the friction and wear experimental device described in the present invention.

[0022] Figure 4 It is a structural schematic diagram of the support module of the present invention.

[0023] Figure 5 It is a structural schematic diagram of the preloading module of the present invention.

[0024] Figure 6 It is a structural schematic diagram of the static test piece module of the present invention.

[0025] Figure 7 It is a structural schematic diagram of the dynamic test piece module of the present invention.

[0026] In the figure:

[0027] A-Support module B-Preload module C-Static specimen module D-Dynamic specimen module

[0028] 1-Workbench 2-Right-angle mounting bracket 3-Normal positioning bracket 4-Horizontal mounting bracket

[0029] 5-Longitudinal mounting bracket 6-Normal adapter bracket 7-Normal mounting bracket 8-Universal ball bearing

[0030] 9-Universal ball bearing base 10-Tangential force sensor 11-Preload piston 12-Preload sleeve

[0031] 13-Large spring plunger 14-Static test piece 15-Static test piece mounting base 16-Static test piece mounting top cover

[0032] 17- Piezoelectric actuator 18- Piezoelectric actuator base 19- Normal connection adapter 20- Normal force sensor

[0033] 21-Normal loading piston 22-Normal loading sleeve 23-Small spring plunger 24-Moving test piece

[0034] 25-acceleration sensor 26-dynamic specimen mounting base 27-dynamic specimen motion platform 28-linear guide assembly

[0035] 29-vibrator 30-cross linear guide 31-I-shaped bracket 32-three-way positioning fixture

[0036] 33-Laser displacement sensor DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The term "tangential direction" refers to the direction parallel to the installation plane of the workbench (1), including "transverse" and "longitudinal". "Transverse" refers to the short side direction of the workbench (1). Figure 2 This is a transverse view of the experimental device of the present invention. "Longitudinal" refers to the long side direction of the workbench (1). Figure 3 It is a longitudinal view of the experimental device of the present invention. "Normal" refers to the normal direction of the installation plane of the workbench (1), which is perpendicular to the friction and wear plane of the static test piece (14) and the dynamic test piece (24).

[0039] like Figure 1 , Figure 2 and Figure 3 As shown, the experimental device of the present invention generally includes a support module (A), four pre-loading modules (B), a static specimen module (C) and a dynamic specimen module (D).

[0040] like Figure 4As shown, the support module (A) includes four right-angle mounting frames (2), four normal positioning brackets (3), two transverse mounting frames (4), two longitudinal mounting frames (5), two normal adapter brackets (6), and a normal mounting frame (7). Each right-angle mounting frame (2) is composed of two rectangular columns and two right-angle mounting edges, each right-angle mounting edge is designed with a moving groove with a width of 16 mm, and the right-angle mounting frame (2) is fixedly connected to the workbench (1) by M16 bolts. The normal positioning bracket (3) is designed with a rectangular through groove, a mounting side plate and a 10 mm positioning groove, which can be installed on the rectangular column of the right-angle mounting frame (2) from the side, so as to move in the normal direction, and realize normal positioning by two M4 bolts. The two transverse mounting frames (4) are designed with a moving groove with a width of 10 mm, and are fixed on the normal positioning bracket (3) by M10 bolts to realize normal and longitudinal constraints, and realize transverse positioning by contacting with the rectangular column plane of the right-angle mounting frame (2). The two longitudinal mounting frames (5) are designed with a movable groove with a width of 10 mm. The longitudinal mounting frames (5) are fixedly connected to the transverse mounting frames (4) using M10 bolts to achieve transverse and normal positioning. The longitudinal positioning is achieved by contacting the rectangular column plane of the right-angle mounting frame (2). The two normal adapter brackets (6) are designed with a movable groove with a width of 10 mm. They are fixedly connected to the upper right-angle mounting edge of the right-angle mounting frame (2) by M10 bolts. The normal mounting frame (7) is designed with a movable groove with a width of 10 mm. It is fixedly connected to the normal adapter bracket (6) by M10 bolts.

[0041] like Figure 5As shown, among the four preloading modules (B), each preloading module includes two universal ball bearings (8), a universal ball bearing base (9), a tangential force sensor (10), a preloading piston (11), a preloading sleeve (12), and a large spring plunger (13). The universal ball bearing (8) is fixedly connected to the universal ball bearing base (9) designed with an M16 threaded hole through its own M16 screw. The tangential force sensor (10) is fixedly connected to the universal ball bearing base (9) designed with an M5 threaded hole and the preloading piston (11) through its own M5 screw. The outer diameter of the sliding section of the preloading piston (11) matches the inner diameter of the preloading sleeve (12), and can slide and rotate relative to each other after assembly. The mounting end of the preloading sleeve (12) is adapted to the mounting groove of the transverse mounting frame (4) or the longitudinal mounting frame (5), and is fixedly connected by an M4 bolt. The preload sleeve (12) is designed with an M30 internal thread and is threadedly connected to a large spring plunger (13) with an M30 external thread. The steel convex pin of the large spring plunger (13) is in tight contact with the end plane of the sliding section of the preload piston (11), and the preload pressure is adjusted by screwing the large spring plunger (13) in and out of the preload sleeve (12). Every two transverse (longitudinal) preload modules (B) form a group, and only allow the static specimen mounting base (15) to translate along the longitudinal (transverse) and normal two degrees of freedom. The two groups of preload modules (B) with orthogonal force transmission paths work together, so that the static specimen mounting base (15) only retains the normal translation freedom, and the friction force of the contact interface between the static specimen (14) and the dynamic specimen (24) in the transverse and longitudinal directions is obtained by measuring the difference in values ​​through a paired tangential force sensor (10). Specifically, two universal ball bearings (8) of a preloading module (B) are tangent to the cross groove plane on the side of the static specimen mounting base (15), and two tightly pressed point contacts are formed in the groove parallel to the mounting side of the preloading sleeve (12). The preloading piston (11) of another preloading module (B) in the same group rotates 90 degrees around the rotation axis, and the corresponding two universal ball bearings (8) are tangent to the cross groove plane on the opposite side of the static specimen mounting base (15), and two tightly pressed point contacts are formed in the groove perpendicular to the mounting side of the preloading sleeve (12). The connecting lines of the two pairs of point contacts are mutually orthogonal, ensuring that the static specimen mounting base (15) only provides preloading pressure to the static specimen (14) and avoids providing any shear force or bending moment in the horizontal or vertical direction, and ensuring that the tangential force sensor (10) only bears preloading pressure in a single direction.

[0042] like Figure 6As shown, the static specimen module (C) includes a static specimen (14), a static specimen mounting base (15), a static specimen mounting top cover (16), a piezoelectric actuator (17), a piezoelectric actuator base (18), a normal connection adapter (19), a normal force sensor (20), a normal loading piston (21), a normal loading sleeve (22), and a small spring plunger (23). The size of the static specimen (14) is adapted to the square mounting hole of the static specimen mounting base (15), and lateral and longitudinal positioning is achieved through interface contact. The top of the square mounting hole is designed with a through hole adapted to an M4 bolt, and a normal fixed connection is achieved using an M4 bolt. The static specimen mounting top cover (16) is fixedly connected to the static specimen mounting base (15) by M4 bolts. The ball head of the working end of the piezoelectric actuator (17) is in tight contact with the static specimen mounting top cover (16), and the force of the piezoelectric actuator (17) is transmitted to the static specimen mounting base (15) and the static specimen (14) through the static specimen mounting top cover (16). The bottom of the piezoelectric actuator base (18) and the mounting end of the piezoelectric actuator (17) are respectively designed with mounting grooves / planes of matching sizes, and positioning is performed through plane contact. The mounting groove at the bottom of the piezoelectric actuator base (18) is designed with a through hole adapted to an M3 bolt, and the M3 bolt is used to achieve the fixed connection between the piezoelectric actuator base (18) and the piezoelectric actuator (17). The normal connection adapter (19) is designed with M3 and M5 internal threads, and one end is fixedly connected to the piezoelectric actuator base (18) using an M3 bolt; the normal force sensor (20) is fixedly connected to the normal connection adapter (19) and the normal loading piston (21) through its own M5 screw. The outer diameter of the sliding section of the normal loading piston (21) matches the inner diameter of the normal loading sleeve (22), and they can slide and rotate relative to each other after assembly. The mounting end of the normal loading sleeve (22) is adapted to the mounting groove of the normal mounting frame (7) and is fixedly connected by an M4 bolt. The normal loading sleeve (22) is designed with an M16 internal thread and is threadedly connected to a small spring plunger (23) with an M16 external thread. The steel convex pin of the small spring plunger (23) is in tight contact with the end plane of the sliding section of the normal loading piston (21). The small spring plunger (23) is screwed into the normal loading sleeve (22), so that the steel convex pin is pushed into the inside of the small spring plunger (23) by the normal loading piston (21), thereby realizing the rated normal preload required by the piezoelectric actuator (17). When the piezoelectric actuator (17) is working, the normal loading piston (21) is completely pressed against the top plane of the thread of the small spring plunger (23), restricting normal sliding, so that the piezoelectric actuator (17) will not move at the installation end to cause force loss. The static specimen mounting base (15) is constrained by four preload modules (B) through point contact of the side cross grooves, and does not move in the horizontal and vertical directions.

[0043] like Figure 7As shown, the dynamic specimen module (D) includes a dynamic specimen (24), two acceleration sensors (25), a dynamic specimen mounting base (26), a dynamic specimen motion platform (27), two linear guide rail assemblies (28), two vibrators (29), a cross linear guide rail (30), an I-shaped bracket (31), two three-way positioning fixtures (32), and two laser displacement sensors (33). The vibrator (29), the I-shaped bracket (31) and the three-way positioning fixture (32) are all fixedly connected to the workbench (1) by M16 bolts. The two orthogonal guide rails of the cross linear guide rail (30) are fixedly connected to the I-shaped bracket (31) and the dynamic specimen motion platform (27) by M6 bolts, respectively, so that the dynamic specimen motion platform (27) can reciprocate in the horizontal and vertical directions relative to the I-shaped bracket (31) through the slider of the cross linear guide rail (30). The two orthogonal sides of the moving specimen motion platform (27) are fixedly connected to the guide rails of the two linear guide assemblies (28) by M4 bolts. The slider and the auxiliary structure of each linear guide assembly (28) are fixedly connected to the end of the top rod of the exciter (29) by M4 threads. By sliding the slider on the linear guide, the two exciters (29) provide exciting force for the moving specimen motion platform (27) in the horizontal and vertical directions without interfering with each other to achieve reciprocating micro-motion, thereby synthesizing the two-dimensional motion of the moving specimen motion platform (27). A square mounting hole is designed on the moving specimen mounting base (26), and a through hole adapted to the M4 bolt is provided at the upper end of the square mounting hole. The mounting end of the moving specimen (24) has an M4 internal thread, and the size of the mounting end is adapted to the square mounting hole. The moving specimen (24) is fixedly connected to the moving specimen mounting base (26) by the plane positioning of the square mounting hole, and the M4 bolt is used to fix the moving specimen (24) to the moving specimen mounting base (26). The dynamic specimen mounting base (26) is fixedly connected to the dynamic specimen motion platform (27) by M4 bolts. Two acceleration sensors (25) are respectively attached to two orthogonal sides of the dynamic specimen (24) to measure the acceleration change of the dynamic specimen (24) during the experiment. Two laser displacement sensors (33) are respectively fixedly connected to two three-way positioning fixtures (32) by M4 bolts, and lasers are irradiated on two sides of the dynamic specimen (24) to obtain the micro displacement changes of the dynamic specimen (24) in the horizontal and vertical directions.

[0044] The specific installation and use process of the present invention is as follows:

[0045] Step 1, realizing two-dimensional reciprocating micro-motion of the moving specimen motion platform (27).

[0046] Place the right-angle mounting frame (2), the vibrator (29), the I-shaped bracket (31) and the three-way positioning fixture (32) in appropriate positions and fix them to the workbench (1) with M16 bolts.

[0047] Furthermore, the two rails of the cross linear guide rail (30) are fixedly connected to the I-shaped bracket (31) and the moving test piece motion platform (27) by means of M6 bolts.

[0048] Furthermore, the two rails of the linear guide assembly (28) are fixedly connected to two orthogonal sides of the moving specimen motion platform (27) via M4 bolts.

[0049] Furthermore, the slider and the auxiliary structure of the linear guide assembly (28) are threadedly connected to the top rod of the exciter (29). Thus, the exciter (29) can provide exciting forces for the moving specimen motion platform (27) in the horizontal and vertical directions without interfering with each other, so that it can realize two-dimensional reciprocating micro-motion.

[0050] Step 2: The static specimen (14) and the dynamic specimen (24) are installed and normal constraints are applied.

[0051] Install the mounting end of the dynamic test piece (24) into the square mounting hole of the dynamic test piece mounting base (26) and use M4 bolts to fix the connection.

[0052] Furthermore, the dynamic test piece mounting base (26) is fixedly connected to the dynamic test piece moving platform (27) by means of M4 bolts, and the dynamic test piece (24) is adjusted to be in an initial position.

[0053] Furthermore, two acceleration sensors (25) are closely attached to two orthogonal side surfaces of the moving specimen (24) to measure the acceleration of the moving specimen (24) during the experiment.

[0054] Furthermore, the normal adapter bracket (6) is fixedly connected to the upper right-angle mounting edge of the right-angle mounting frame (2) by means of M10 bolts.

[0055] Furthermore, the mounting end of the static specimen (14) is inserted into the square mounting hole of the static specimen mounting base (15), fixedly connected using M4 bolts, and then the static specimen mounting top cover (16) is fixedly connected to the static specimen mounting base (15) using M4 bolts.

[0056] Furthermore, the static test piece (14) is placed on the friction surface of the dynamic test piece (24).

[0057] Furthermore, the mounting end of the piezoelectric actuator (17) is inserted into the mounting groove of the piezoelectric actuator base (18), and fixedly connected using M3 bolts, and then the piezoelectric actuator base (18) and the normal connection adapter (19) are fixedly connected using M3 bolts.

[0058] Furthermore, the normal force sensor (20) is fixedly connected to the normal connection adapter (19) and the normal loading piston (21) in sequence through a screw.

[0059] Further, the normal loading piston (21) is installed into the normal loading sleeve (22), and the normal loading sleeve (22) is installed into the mounting groove of the normal mounting frame (7) and fixedly connected using M4 bolts.

[0060] Furthermore, the ball head of the working end of the piezoelectric actuator (17) is pressed into contact with the static specimen mounting top cover (16), and the normal mounting frame (7) is fixedly connected to the normal adapter bracket (6) by means of M10 bolts.

[0061] Furthermore, the small spring plunger (23) is screwed into the normal loading sleeve (22) through a threaded connection, so that the steel convex pin is pushed into the small spring plunger (23) by the normal loading piston (21), thereby achieving the rated normal preload required by the piezoelectric actuator (17). At this point, the normal motion freedom of the static test piece (14) and the dynamic test piece (24) is completely constrained. When the piezoelectric actuator (17) is working, the normal loading piston (21) and the top plane of the thread of the small spring plunger (23) are completely pressed, so that the piezoelectric actuator (17) will not move at the installation end to cause force loss. The normal positive pressure value on the test interface is the sum of the value measured by the normal force sensor (20) and the gravity on the static test piece (14), the static test piece mounting base (15), the static test piece mounting top cover (16), the piezoelectric actuator (17), the piezoelectric actuator base (18) and the normal connection adapter (19).

[0062] Step 3, install the preload module (B).

[0063] The universal ball bearing (8) is fixedly connected to the universal ball bearing base (9) via a screw rod, and the tangential force sensor (10) is then fixedly connected to the universal ball bearing base (9) and the preload piston (11) via the screw rod in turn.

[0064] Further, the preload piston (11) is installed into the preload sleeve (12), and the large spring plunger (13) is screwed into the preload sleeve (12) through a thread. At this point, the installation of one preload module (B) is completed, and this step is repeated to complete the installation of the other three preload modules (B).

[0065] Step 4: tangentially preload the static specimen mounting base (15).

[0066] Install the mounting end of the preloading sleeve (12) in each preloading module (B) into the mounting groove of the transverse mounting frame (4) or the longitudinal mounting frame (5), and use M4 bolts to fix the connection.

[0067] Furthermore, the normal positioning bracket (3) is installed on the rectangular column of the right-angle mounting frame (2) from the side.

[0068] Furthermore, the transverse mounting frame (4) is fixedly connected to the normal positioning bracket (3) using M10 bolts, and the longitudinal mounting frame (5) is fixedly connected to the transverse mounting frame (4) using M10 bolts. Both the transverse mounting frame (4) and the longitudinal mounting frame (5) are close to the rectangular column of the right-angle mounting frame (2).

[0069] Furthermore, the normal positioning of the normal positioning support (3), the longitudinal positioning of the transverse mounting frame (4), and the transverse positioning of the longitudinal mounting frame (5) are adjusted, so that in each of the two transverse (longitudinal) preloading modules (B) as a group, the two universal ball bearings (8) of one preloading module (B) roll in the horizontal groove of the cross groove on the side of the static specimen mounting base (15), and the preloading piston (11) of the other preloading module (B) rotates 90° around the rotation axis, and the corresponding two universal ball bearings (8) roll in the vertical groove parallel to the cross groove on the side of the static specimen mounting base (15).

[0070] Further, all the large spring plungers (13) are gradually screwed into the preload sleeve (12) until the tangential force sensor (10) in the preload module (B) shows sufficient lateral and longitudinal preload values. At this point, the other degrees of freedom of motion of the static specimen (14) are completely constrained.

[0071] Step 5: Install and debug the laser displacement sensor (33).

[0072] Two laser displacement sensors (33) are fixedly connected to two three-way positioning fixtures (32) respectively by M4 bolts, and the position and structure of the three-way positioning fixtures (32) are adjusted so that laser light is irradiated on two side surfaces of the moving test piece (24) to obtain minute displacement changes of the moving test piece (24) in the transverse and longitudinal directions.

[0073] When in use, the experimental device has the following working characteristics:

[0074] During the test, the vibrator (29) provides exciting forces to the moving specimen motion platform (27) in the horizontal and vertical directions without interfering with each other, so that the moving specimen (24) performs two-dimensional reciprocating micro-motion with the moving specimen motion platform (27); the static specimen (14), the static specimen mounting base (15) and the static specimen mounting top cover (16) are fixed above the moving specimen (24) through the static specimen module (C) and four pre-loading modules (B), and are in contact with the friction surface of the moving specimen (24).

[0075] In the transverse (longitudinal) direction, two pairs of universal ball bearings (8) whose lines of action points are orthogonal to each other ensure that the transverse (longitudinal) friction force and the transverse (longitudinal) preload load on the static specimen (14) are only transmitted along the complete transmission chain of preload sleeve (12) → large spring plunger (13) → preload piston (11) → tangential force sensor (10) → universal ball bearing base (9) → universal ball bearing (8) → static specimen mounting base (15) → universal ball bearing (8) → universal ball bearing base (9) → tangential force sensor (10) → preload piston (11) → large spring plunger (13) → preload sleeve (12). The ball head of the piezoelectric actuator (17) and the steel convex pin of the small spring plunger (23) ensure that the normal preload provided by the small spring plunger (23) and the periodic time-varying positive pressure provided by the piezoelectric actuator (17) are only normally transmitted along the complete transmission chain of normal loading sleeve (22) → small spring plunger (23) → normal loading piston (21) → normal force sensor (20) → normal connection adapter (19) → piezoelectric actuator base (18) → piezoelectric actuator (17) → static specimen mounting top cover (16) → static specimen mounting base (15) → static specimen (14) → dynamic specimen (24).

[0076] By changing the screw-in lengths of the large spring plunger (13) and the small spring plunger (23), and adjusting the output settings of the piezoelectric actuator (17) and the exciter (29), the evolution law of the interface hysteresis characteristics under different combinations of time-varying positive pressure and two-dimensional relative motion trajectory of the interface and its influence on wear can be realized. Compared with the existing friction and wear tester, the present invention has the characteristics of being able to accurately reproduce the real load state of the contact interface under service conditions, and has a simple structure and is easy to adjust, and can be used to study the hysteresis characteristics and wear evolution of the friction interface of the assembly structure.

Claims

1. A friction and wear tester capable of realizing time-varying positive pressure and two-dimensional interface motion, comprising a support module, four preload modules, a static specimen module and a dynamic specimen module; characterized in that: The support module includes four right-angle mounting frames, four normal positioning brackets, two transverse mounting frames, two longitudinal mounting frames, two normal adapter brackets and a normal mounting frame; the preload module includes two universal ball bearings, a universal ball bearing base, a tangential force sensor, a preload piston, a preload sleeve and a large spring plunger; the static specimen module includes a normal force sensor, a static specimen, a static specimen mounting base, a static specimen mounting top cover, a piezoelectric actuator, a piezoelectric actuator base, a normal connection adapter The dynamic specimen module comprises a dynamic specimen, two acceleration sensors, a dynamic specimen mounting base, a dynamic specimen motion platform, two linear guide rail assemblies, two vibrators, a cross linear guide rail, an I-shaped bracket, two three-way positioning fixtures and two laser displacement sensors; wherein the two vibrators respectively provide exciting force for the dynamic specimen motion platform in the horizontal and vertical directions without interfering with each other to realize reciprocating micro-motion, thereby synthesizing the two-dimensional motion of the dynamic specimen motion platform; In the preloading module, the universal ball bearing is in point contact with the static specimen mounting base and is connected to the universal ball bearing base through its own screw; the tangential force sensor is fixedly connected to the universal ball bearing base and the preloading piston through its own screw; the preloading piston is installed in the preloading sleeve; the preloading sleeve is adapted to the mounting groove of the transverse mounting frame or the longitudinal mounting frame and is fixedly connected through bolts; the preloading sleeve is threadedly connected to the large spring plunger; the steel convex pin of the large spring plunger is in tight contact with the end plane of the sliding section of the preloading piston, and the preloading pressure is adjusted by screwing the large spring plunger in and out of the preloading sleeve; Every two transverse or longitudinal preloading modules form a group. The two universal ball bearings of one preloading module are tangent to the cross groove plane on the side of the static specimen mounting base, forming two tightly pressed point contacts in the groove parallel to the side of the preloading sleeve mounting. The preloading piston of another preloading module in the same group rotates 90° around the rotation axis, and the corresponding two universal ball bearings are tangent to the cross groove plane on the side of the static specimen mounting base, forming two tightly pressed point contacts in the groove perpendicular to the side of the preloading sleeve mounting. The connecting lines of the two pairs of point contacts are mutually Orthogonal, ensuring that the static specimen mounting base only provides preload pressure to the static specimen and avoids providing any shear force or bending moment in the horizontal or vertical direction, and ensuring that the tangential force sensor only bears the preload pressure in a single direction. The two sets of preload modules with orthogonal force transmission paths work together, so that the static specimen mounting base only retains the normal translational degree of freedom; the tangential force sensors of the paired preload modules are used to measure the friction force of the contact interface between the static specimen and the dynamic specimen in the horizontal and vertical directions; the static specimen mounting base is constrained by the four preload modules and does not move in the horizontal and vertical directions; In the static specimen module, the static specimen is fixedly connected to the static specimen mounting base through square mounting holes and bolts; the static specimen mounting top cover is fixedly connected to the static specimen mounting base through bolts; the piezoelectric actuator ball head is in tight contact with the static specimen mounting top cover; the piezoelectric actuator base and the piezoelectric actuator mounting end are fixedly connected through mounting grooves and bolts; the normal connection adapter is fixedly connected to the piezoelectric actuator base using bolts; the normal force sensor is fixedly connected to the normal connection adapter and the normal loading piston through its own screw; the normal loading piston is installed in the normal loading sleeve; the normal loading sleeve is fixedly connected to the normal mounting frame through mounting groove bolts; The normal loading sleeve is fixedly connected to the small spring plunger by threads, and the steel convex pin of the small spring plunger is in tight contact with the end plane of the sliding section of the normal loading piston. The small spring plunger is screwed into the normal loading sleeve so that the steel convex pin is pushed into the small spring plunger by the normal loading piston, thereby realizing the rated normal preload required by the piezoelectric actuator; when the piezoelectric actuator is working, the normal loading piston is completely pressed against the top plane of the small spring plunger thread to constrain normal sliding, so that the piezoelectric actuator will not move at the installation end to cause force loss.

2. A friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 1, characterized in that: In the support module, the right-angle mounting frame is fixedly connected to the workbench by bolts; the normal positioning bracket is installed on the rectangular column of the right-angle mounting frame from the side; the transverse mounting frame is fixed to the normal positioning bracket by bolts; the longitudinal mounting frame is connected to the transverse mounting frame by bolts; the normal adapter bracket is fixedly connected to the right-angle mounting frame by bolts; and the normal mounting frame is fixedly connected to the normal adapter bracket by bolts.

3. The friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 1, characterized in that: In the dynamic specimen module, the vibrator, I-bracket and three-way positioning fixture are all fixedly connected to the workbench by bolts; the I-bracket and the dynamic specimen motion platform are connected by cross linear guides; the two sides of the dynamic specimen motion platform are connected to the top rod of the vibrator by linear guide assemblies; the dynamic specimen and the dynamic specimen mounting base are fixedly connected by square mounting holes and bolts; the dynamic specimen mounting base is fixedly connected to the dynamic specimen motion platform by bolts; two acceleration sensors are tightly attached to two orthogonal sides of the dynamic specimen; and two laser displacement sensors are fixedly connected to the three-way positioning fixture by bolts.

4. A method for realizing a friction and wear tester capable of realizing time-varying positive pressure and two-dimensional interface motion, characterized in that: Using the friction and wear tester according to any one of claims 1 to 3 comprises the following steps: Step 1: Realization of two-dimensional reciprocating micro-motion of the moving specimen motion platform; Step 2: Installation of static and dynamic specimens and application of normal constraints; Step 3: Install the preloaded module; Step 4: Perform tangential preloading on the static specimen mounting base; Step 5: Install and debug the laser displacement sensor; fix the two laser displacement sensors to the two three-way positioning fixtures through M4 bolts respectively, adjust the position and structure of the three-way positioning fixture so that the laser irradiates the two sides of the moving specimen to obtain the small displacement changes of the moving specimen in the lateral and longitudinal directions.

5. The method for realizing a friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 4, characterized in that: In step 1, the right-angle mounting frame, the vibrator, the I-shaped bracket and the three-way positioning fixture are placed in appropriate positions and fixedly connected to the workbench by M16 bolts; further, the two tracks of the cross linear guide are fixedly connected to the I-shaped bracket and the moving platform of the dynamic specimen by M6 bolts; Further, the two rails of the linear guide assembly are fixedly connected to two orthogonal sides of the moving platform of the moving specimen by M4 bolts; Furthermore, the slider and the auxiliary structure of the linear guide assembly are threadedly connected to the top rod of the exciter; at this point, the exciter can provide exciting forces for the moving platform of the moving specimen in the horizontal and vertical directions without interfering with each other, so that it can achieve two-dimensional reciprocating micro-motion.

6. The method for realizing a friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 4, characterized in that: In step 2, install the dynamic test piece mounting end into the square mounting hole of the dynamic test piece mounting base and fix the connection with M4 bolts; Furthermore, the dynamic specimen mounting base is fixedly connected to the dynamic specimen motion platform through M4 bolts, and the dynamic specimen is adjusted to an initial position; Furthermore, two acceleration sensors are placed on two orthogonal sides of the moving specimen to measure the acceleration of the moving specimen during the experiment. Furthermore, the normal adapter bracket is fixedly connected to the upper right-angle mounting edge of the right-angle mounting bracket by means of M10 bolts; Further, the static specimen installation end is installed into the square installation hole of the static specimen installation base, and fixedly connected with the M4 bolt, and then the static specimen installation top cover is fixedly connected with the static specimen installation base through the M4 bolt; Furthermore, the static specimen is placed on the friction surface of the dynamic specimen; Further, the piezoelectric actuator mounting end is installed into the mounting groove of the piezoelectric actuator base, and fixedly connected using M3 bolts, and then the piezoelectric actuator base is fixedly connected to the normal connection adapter using M3 bolts; Further, the normal force sensor is fixedly connected to the normal connection adapter and the normal loading piston in sequence through a screw; Further, the normal loading piston is installed into the normal loading sleeve, and the normal loading sleeve is installed into the mounting groove of the normal mounting frame and fixedly connected using M4 bolts; Further, the ball head of the working end of the piezoelectric actuator is pressed into contact with the top cover of the static specimen installation, and the normal mounting frame is fixedly connected to the normal adapter bracket by M10 bolts; Furthermore, through a threaded connection, the small spring plunger is screwed into the normal loading sleeve, so that the steel pin is pushed into the small spring plunger by the normal loading piston, thereby achieving the rated normal preload required by the piezoelectric actuator; at this point, the normal movement freedom of the static specimen and the dynamic specimen is completely constrained, and when the piezoelectric actuator is working, the normal loading piston and the top plane of the small spring plunger thread are completely pressed, so that the piezoelectric actuator will not move at the installation end and cause force loss; the normal positive pressure value received by the test interface is the sum of the value measured by the normal force sensor and the gravity received by the static specimen, the static specimen mounting base, the static specimen mounting top cover, the piezoelectric actuator, the piezoelectric actuator base and the normal connection adapter.

7. The method for realizing a friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 4, characterized in that: In step 3, the universal ball bearing is fixedly connected to the universal ball bearing base through a screw, and then the tangential force sensor, the universal ball bearing base and the preload piston are fixedly connected in turn through the screw; further, the preload piston is installed into the preload sleeve, and the large spring plunger is screwed into the preload sleeve through a thread; at this point, one preload module is installed, and step 3 is repeated to complete the installation of the other three preload modules.

8. The method for realizing a friction and wear tester capable of realizing time-varying normal pressure and two-dimensional interface motion according to claim 4, characterized in that: In step 4, install the mounting end of the preloading sleeve in each preloading module into the mounting slot of the transverse mounting frame or the longitudinal mounting frame, and fix the connection with M4 bolts; Further, the normal positioning bracket is mounted on the rectangular column of the right-angle mounting frame from the side; Further, the transverse mounting frame is fixedly connected to the normal positioning bracket using M10 bolts, and the longitudinal mounting frame is fixedly connected to the transverse mounting frame using M10 bolts, and both the transverse mounting frame and the longitudinal mounting frame are close to the rectangular column of the right-angle mounting frame; Further, the normal positioning of the normal positioning support is adjusted, the longitudinal positioning of the transverse mounting frame is adjusted, and the transverse positioning of the longitudinal mounting frame is adjusted, so that in every two transverse or longitudinal preloading modules as a group, the two universal ball bearings of one preloading module roll in the horizontal groove of the cross groove on the side of the static specimen mounting base, and the preloading piston of the other preloading module rotates 90° around the rotation axis, and the corresponding two universal ball bearings roll in the vertical groove of the cross groove on the parallel side of the static specimen mounting base; Furthermore, all large spring plungers are gradually screwed into the preload sleeve until the tangential force sensor in the preload module shows sufficient lateral and longitudinal preload load values; at this point, the freedom of motion of the static specimen is completely constrained.

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