Friction pair

Abstract

The friction pair comprises a fixing body, a rotating body and a sealing assembly, the fixing body is provided with a downwards-sunken testing groove, the testing groove is provided with a circular ring face, the bottom of the testing groove is provided with a plurality of protruding edges protruding upwards, and the protruding edges are evenly arranged in a radial shape with the circle center of the testing groove as the center; the rotating body can be embedded into the test groove and rotate; the sealing assembly is used for sealing an annular gap formed between the rotating body and the annular surface of the testing groove. According to the friction pair, high-viscosity fluid and powder materials can form a stable, continuous and concentrated shearing field in a friction test, the reliability of data acquisition is ensured, the performance evolution rule of the materials under the continuous shearing condition is truly reflected, and the accuracy and repeatability of data acquisition are improved.

Description

Technical Field

[0001] This invention relates to the field of tribological testing technology, and more particularly to a friction pair. Background Technology

[0002] As a core piece of equipment for studying the tribological properties of materials, the friction testing apparatus has a systematic and standardized design and testing process. This equipment typically consists of a loading system, a friction pair system, a drive system, a measurement system, and a data acquisition and control system.

[0003] In routine operation, the operator first installs and cleans the sample, then sets parameters such as load, speed, and time using the control software. After the equipment is started, the drive system moves the sample relative to itself, the loading system applies a normal load synchronously, and the measurement system captures the friction force signal in real time and calculates the friction coefficient according to a standard formula, generating a dynamic curve. The test automatically stops after reaching the preset endpoint, and performance evaluation is finally completed by analyzing the wear morphology and data curves. This mature system plays an important role in the study of wear characteristics of solid material surfaces and lubrication behavior of low-viscosity fluids, providing a reliable basis for the selection and optimization of engineering materials.

[0004] However, existing technologies have fundamental flaws when it comes to testing high-viscosity fluids (such as paste-like polymers) and powder materials.

[0005] At the measurement object level, traditional friction pair structures include four-ball, three-plate, ring-block, reciprocating, end-face, and pin-disc types. Their design principles are only applicable to the shear behavior of solid interfaces or low-viscosity fluids, and cannot effectively construct the internal shear field required for high-viscosity fluids and powder materials. The measurement of the internal friction coefficient of such special materials requires the sample to maintain uniform stress under continuous and stable shear conditions. However, the geometry of existing friction pairs makes the material prone to accumulation, slippage, or local stress concentration, making it impossible to quantify the true internal friction characteristics.

[0006] At the level of testing methods, traditional methods such as the inclined plane method and the flat plate method, which are specifically designed for fluid internal friction, are limited by the structure of the apparatus and have difficulty maintaining a continuous and stable shear motion field. Their unsteady testing environment causes the material to undergo an alternating process of intermittent shearing and stillness, which cannot simulate the sustained friction state in actual working conditions and leads to violent fluctuations in the friction force signal. This unsteady testing environment cannot guarantee the reliability of data acquisition, nor can it truly reflect the performance evolution law of the material under continuous shear conditions, which seriously affects the accuracy and repeatability of data acquisition.

[0007] Furthermore, there is a lack of measurement dimensions. Existing equipment generally lacks the ability to monitor the thermal effects during friction. In the continuous shearing process of high-viscosity fluids and powder materials, the temperature rise caused by the conversion of mechanical energy into heat energy will significantly affect the rheological properties of the material. However, traditional friction testing instruments neither integrate reliable temperature monitoring modules nor can they establish a correlation model between frictional heat and the shearing process, which makes the quantitative analysis of frictional heat generation a technical blind spot.

[0008] More importantly, existing equipment generally lacks the ability to simultaneously monitor the frictional heat effect. During continuous shearing of high-viscosity fluids and powders, mechanical energy is dissipated and converted into significant heat energy, causing changes in the material's temperature gradient and directly affecting its rheological properties. However, traditional friction testing instruments are neither equipped with reliable temperature sensing modules nor have a mechanism for analyzing the correlation between thermal effects and the shearing process, making the law of frictional heat generation an unquantifiable technical blind spot.

[0009] These intertwined technical bottlenecks (failure to measure internal friction coefficient, lack of stable shear environment, and insufficient thermal effect monitoring capability) severely restrict the research and development progress of cutting-edge fields such as polymer composites, special greases, and powder engineering. There is an urgent need to develop new testing schemes to achieve synergistic characterization of friction behavior and thermal effects under continuous shear conditions.

[0010] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a friction pair that enables high-viscosity fluids and powder materials to form a stable, continuous, and concentrated shear field during friction testing, ensuring the reliability of data acquisition, truly reflecting the performance evolution law of materials under continuous shear conditions, and improving the accuracy and repeatability of data acquisition.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A friction pair, comprising: The fixed body has a downwardly recessed test groove with a circular annular surface. The bottom of the test groove is provided with multiple upwardly protruding ridges, which are arranged radially and evenly around the center of the test groove. A rotating body capable of being embedded in a test slot and rotating; A sealing assembly for sealing the circumferential gap formed between the rotating body and the annular surface of the test groove.

[0013] A further technical solution includes a temperature measuring mechanism for measuring the temperature of the upper region of the convex ridge inside the test groove, the temperature measuring mechanism comprising: At least one of the protruding ridges has a mounting hole, and a thermocouple is provided in the mounting hole; And / or, the fixed body is provided with a viewing window, and an infrared imager is provided outside the fixed body to measure the temperature of the upper area of ​​the protruding ridge through the viewing window.

[0014] A further technical solution is that the bottom of the test slot is provided with a detachable lower partition, and the protruding rib is provided on the upper surface of the lower partition; The lower surface of the lower partition plate has a locking structure between it and the bottom surface of the test tank to restrict the rotation of the lower partition plate. The bottom of the fixing body has a top hole corresponding to the test slot.

[0015] A further technical solution is that the bottom of the test tank is provided with an exhaust hole to the side.

[0016] A further technical solution is that the top surface of the protruding ridge is a plane or an upwardly arched arc surface; The two sides of the root of the convex ridge have rounded chamfers, and the chamfer on the side of the convex ridge facing the rotating body is greater than or equal to the chamfer on the side of the convex ridge facing away from the rotating body. The side of the convex ridge facing the rotating body is either a vertical surface or an inclined surface that gradually widens towards the root of the convex ridge.

[0017] A further technical solution is that the cross-section of the test groove is circular, the rotating body is a cylinder adapted to the test groove, and the sealing component is disposed between the annular surface of the test groove and the outer wall of the rotating body. Alternatively, the test groove has a circular cross-section, and the annular surface of the test groove includes an inner annular surface and an outer annular surface arranged concentrically. The rotating body is a hollow cylinder adapted to the test groove. The sealing assembly includes two sets, respectively disposed between the outer wall of the rotating body and the outer annular surface of the test groove, and between the inner wall of the rotating body and the inner annular surface of the test groove.

[0018] A further technical solution is that the upper end of the annular surface of the test groove has a recessed mounting groove, the bottom surface of the mounting groove is an inclined guide surface, and the guide surface is inclined downward toward the inside of the test groove. The sealing assembly includes a floating ring sealing structure, the floating ring sealing structure comprising: Floating rings, embedded in the mounting groove; and The end cap is pressed against the upper surface of the floating ring. The end cap and the fixed body can press down on the floating ring to make it hold the rotating body tightly.

[0019] A further technical solution is that the floating ring comprises: Support section; and A sealing part is fixed to the support part and used to seal in contact with the rotating body. The surface of the sealing part is provided with a spiral groove, and the spiral direction of the spiral groove from bottom to top is opposite to the rotation direction of the rotating body.

[0020] A further technical solution is that the sealing assembly includes a labyrinth sealing structure, and the labyrinth sealing structure includes turbulence teeth disposed on the annular surface of the test groove; The turbulence-inducing teeth extend circumferentially to form a closed circumferential structure; The turbulence-inducing teeth have multiple channels, which are arranged at intervals along the axial direction.

[0021] A further technical solution is that the sealing assembly includes an air curtain sealing structure, the air curtain sealing structure comprising: The equalizing groove is formed on the annular surface of the test groove and located at the top of the test groove; A high-pressure air passage is provided on a fixed body. The high-pressure air passage has a connecting section. The connecting section is connected to the pressure equalization groove and is set at an angle of 30-60° with the pressure equalization groove.

[0022] The beneficial effects of adopting the above technical solution are as follows: When using this friction pair for testing, the material to be tested is placed in the test chamber, and the rotating body rotates relative to the stationary body under external drive. Due to the radially uniform distribution of the convex ridges, the shear force is uniformly transmitted in the radial direction, preventing local accumulation or uneven flow of high-viscosity fluids or powder materials during rotation. The convex ridges also divide the material to be tested into two different flow domains: the upper flow domain is located above the convex ridges, where the material moves with the rotating body; the lower flow domain is located within the fan-shaped area, where the material remains stationary with the stationary body and the convex ridges. The interface between these two flow domains is concentrated at the upper end of the convex ridges, forming a stable shear friction surface.

[0023] The shear friction surface formed at the upper end of the convex ridge is stable and uniform, and is a continuous motion field that can truly reflect the performance evolution law of the material under continuous shear conditions.

[0024] During testing, the interaction between the rotating body and the test chamber in the friction pair enables controllable relative motion, generating a uniform shearing effect. This provides a fundamental condition for measuring the internal friction coefficient of high-viscosity fluids and powder materials. The stable shear field ensures that the material's performance evolution under continuous shear conditions is accurately reflected, improving the reliability of the test data. This solves the problem of the inability to form a stable, continuous, and concentrated shear field in friction testing of high-viscosity fluids and powder materials. Attached Figure Description The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a schematic diagram of the isometric structure of the friction pair in this invention; Figure 2 This is a top view of the friction pair in this invention. Figure 3 for Figure 2 A schematic diagram of the cross-sectional structure along the AA direction; Figure 4 This is an isometric structural diagram of the lower partition in this invention; Figure 5 This is a feasible shape (rectangular) for the protruding edge on the lower partition plate in this invention. Figure 6 This is a feasible shape (right trapezoid) for the protruding edge on the lower partition plate in this invention. Figure 7 This is a feasible shape (wavy) for the protruding ridge on the lower partition plate in this invention. Figure 8 for Figure 3 A magnified schematic diagram of the local structure at point I; Figure 9 This is a schematic diagram of the high-pressure gas flow direction on the outer end cap in this invention; Figure 10 This is a schematic diagram of the high-pressure gas flow direction on the inner end cap in this invention; Figure 11 This is a schematic diagram of the connection between the equalizing groove and the high-pressure air passage in this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] In the description of this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] like Figures 1-11 As shown, a friction pair can be used for testing the friction properties of high-viscosity fluids and powder materials. This friction pair can form a stable and continuous shear field and achieve effective sealing, solving the technical problem that existing technologies cannot accurately measure the friction of such materials.

[0029] Example 1 The friction pair includes a fixed body 3, a rotating body 1, and a sealing assembly.

[0030] The fixed body 3 is a static, rigid substrate, preferably made of structural steel or medium carbon steel. The fixed body 3 has a downwardly recessed test groove with a circular annular surface, ensuring that the rotating body 1 can be smoothly embedded and form continuous circumferential motion. The bottom of the test groove has multiple upwardly protruding ribs 402, which are radially and uniformly arranged around the center of the test groove. In specific implementations, the number of ribs 402 can be set to 2-6 depending on the rheological properties of the material 5 being tested; for example, four ribs 402 can be evenly arranged at 90-degree intervals. The ribs 402 extend from the center of the test groove to its edge, dividing the bottom of the test groove into multiple independent fan-shaped regions. This structure effectively blocks the lateral migration path of the material and maintains the stability of the shear state in each region.

[0031] The rotating body 1 is a rigid component connected to an external drive mechanism, preferably made of structural steel or medium carbon steel. The rotating body 1 can be embedded in the test chamber and rotate relative to the fixed body 3, serving as the active component generating relative motion. Depending on the object being measured, the working surface of the rotating body 1 in contact with the material (i.e., the lower end face of the rotating body 1) can be a plane perpendicular to the axis of the rotating body 1, or it can be an inverted conical surface. This inverted conical surface is a cone-shaped surface formed by rotating a generatrix around the axis of the rotating body 1. This inverted conical surface can generate a velocity component from the center outwards on the test material, thereby breaking the flow dead zone in the rotation center region, promoting the circulation and mixing of the material in the test chamber, ensuring the uniformity of the shear field and the diffusion of heat, making it more suitable for measuring non-Newtonian fluids, and providing a better constant shear rate field to meet different testing requirements. As a preferred technical solution, the angle between the generatrix of the inverted conical surface and the plane perpendicular to the axis of the rotating body 1 is no greater than 5°, thus achieving the best balance between ensuring effective flow guidance and maintaining sufficient structural strength.

[0032] The sealing assembly is used to seal the circumferential gap formed between the rotating body 1 and the annular surface of the test groove, preventing leakage of the test material during shearing. The sealing assembly can employ one or more combinations of floating ring sealing structures, air curtain sealing structures, labyrinth sealing structures, and lip sealing structures to adapt to the characteristics of different materials. Effective sealing ensures that the pressure and material volume within the test chamber (i.e., the test groove) remain stable, providing a guarantee for continuous shearing and obtaining reliable and repeatable experimental data.

[0033] When using this friction pair for testing, the material to be tested 5 is placed in the test chamber, and the rotating body 1 rotates relative to the stationary body 3 under external drive. Due to the radial and uniform distribution of the convex ridges 402, the shear force is uniformly transmitted in the radial direction, preventing local accumulation or uneven flow of high-viscosity fluids or powder materials during rotation. The arrangement of the convex ridges 402 also divides the material to be tested 5 into two different flow domains: the upper flow domain is located above the convex ridges 402, where the material moves with the rotating body 1; the lower flow domain is located in the fan-shaped area, where the material remains stationary with the stationary body 3 and the convex ridges 402. The interface between these two flow domains is concentrated at the upper end of the convex ridges 402, forming a stable shear friction surface.

[0034] The shear friction surface formed at the upper end of the convex 402 is stable and uniform, and is a continuous motion field that can truly reflect the performance evolution law of the material under continuous shear conditions.

[0035] During testing, the interaction between the rotating body 1 and the test chamber enables controllable relative motion, generating a uniform shearing effect. This provides a fundamental condition for measuring the internal friction coefficient of high-viscosity fluids and powder materials. The stable shear field ensures that the material's performance evolution under continuous shear conditions is accurately reflected, improving the reliability of the test data. This solves the technical problem of not being able to form a stable, continuous, and concentrated shear field in friction testing of high-viscosity fluids and powder materials.

[0036] Example 2 The friction pair also includes a temperature measuring mechanism for measuring the temperature of the upper region of the protruding ridge inside the test groove.

[0037] Specifically, the temperature measuring mechanism may have a mounting hole 401 on at least one of the protruding ridges 402, and a thermocouple is installed in the mounting hole 401. The thermocouple may be a type K, J, or T thermocouple, used to convert the heat energy signal converted from mechanical energy during friction into a collectable electrical signal in real time.

[0038] During the friction test, the material shear rate at the protrusion 402 changes drastically, providing an ideal measurement environment for the frictional temperature rise experiment. By embedding the thermocouple into the mounting hole 401 inside the protrusion 402, the temperature sensing element is directly located at the frictional area at the bottom of the test tank, in contact with the rotating body 1. Since the protrusion 402 is a key structure separating the independent area at the bottom of the test tank, it generates frictional heat when moving relative to the rotating body 1. The thermocouple, being close to this heat source, can quickly capture temperature changes. At the same time, the mounting hole 401 ensures a stable connection between the thermocouple and the protrusion 402, preventing interference from fluid flow during temperature signal acquisition, thereby achieving accurate capture and real-time data conversion of the frictional heating effect.

[0039] A through hole is provided at the bottom of the fixing body 3 at the position corresponding to the mounting hole 401. When installing the thermocouple, the temperature sensing end of the thermocouple is tightly embedded in the bottom of the mounting hole 401 and fixed with high-temperature resistant insulating material; the signal line of the thermocouple is led downward through the through hole at the bottom of the fixing body 3 to the external data acquisition system to ensure that the temperature signal is continuously and stably transmitted during the friction process.

[0040] The number of thermocouples can be one or more. When multiple thermocouples are set, a circumferentially distributed structure is used to obtain more comprehensive temperature field distribution information.

[0041] The temperature measuring mechanism can also be a device with a viewing window on the fixed body, and an infrared imager outside the fixed body that measures the temperature of the upper area of ​​the convex ridge through the viewing window. The viewing window includes a through-hole in the fixed body, and a transparent observation plate is provided on the through-hole. The observation plate can be made of a high-strength, high-temperature resistant, and high-transmittance material, such as quartz glass, which can allow infrared radiation and visible light to pass through while maintaining the airtightness of the test tank.

[0042] During the friction test, an infrared imager continuously and in real-time scans the material area undergoing intense shearing on the upper part of the convex edge through a viewing window. The infrared imager captures two-dimensional infrared radiation information of the upper flow area and converts it into a temperature field distribution image (i.e., a thermogram), which is then transmitted to the data acquisition system. Infrared thermometry can more intuitively and comprehensively display the temperature distribution of the entire shear plane, thereby accurately identifying the location and temperature of local hot spots.

[0043] In addition, the temperature measurement mechanism can also include both thermocouple and infrared temperature measurement. Cross-validating the average regional temperature measured by the infrared imager with the readings of the thermocouples with embedded protrusions further improves the reliability of the entire temperature measurement system.

[0044] Through the above scheme, this application realizes real-time monitoring of the temperature change of the friction interface, which enables the accurate quantification of the frictional heat generated by high-viscosity fluids or powder materials during continuous shearing, thereby providing a reliable basis for evaluating the rheological properties and performance evolution of materials.

[0045] Example 3 like Figure 4 As shown, the bottom of the test tank is provided with a removable lower partition 4. The lower partition 4 is a load-bearing component that can be detached from the bottom of the test tank, and is preferably made of structural steel or medium carbon steel. The protruding rib 402 is provided on the upper surface of the lower partition 4 and can be integrally formed with the lower partition 4. By integrating the protruding rib 402 into the upper surface of the removable lower partition 4, an independent wear unit is formed. After the protruding rib 402 wears, only the lower partition 4 needs to be replaced, avoiding the need to replace the entire fixing body 3, thereby reducing maintenance costs and maintaining test continuity.

[0046] The lower surface of the lower partition 4 has a locking structure between it and the bottom surface of the test tank to restrict the rotation of the lower partition 4. The locking structure is a mechanical interlocking mechanism that constrains the circumferential displacement of the lower partition 4, and can be implemented as follows: a first positioning countersunk hole 302 is opened at the bottom of the test tank, and a first positioning pin 7 is inserted into the first positioning countersunk hole 302. A second positioning countersunk hole 403 that mates with the first positioning pin 7 is provided on the lower surface of the lower partition 4. The locking structure can also be implemented using a keyway fit or a concave-convex interlocking method to ensure that the lower partition 4 remains circumferentially stable during the movement of the rotating body 1, preventing distortion of the shear field due to deflection, and ensuring uniform transmission of shear force during the shearing process of high-viscosity materials.

[0047] The bottom of the fixing body 3 has an ejector hole corresponding to the test slot. The ejector hole is a through hole opened at the bottom of the fixing body 3, designed as a smooth through hole. After the test is completed, an upward axial force is applied by inserting a push rod tool through the hole, causing the lower partition 4 to disengage from the fitting structure axially, providing a bottom-up operation path for disassembling the lower partition 4, realizing the rapid replacement of worn parts, and facilitating the discharge of the tested material 5.

[0048] It should be noted that by matching the dimensions of the annular surface of the lower partition 4 with the annular surface of the test groove (such as interference fit, setting a sealing ring on the annular surface of the lower partition 4, etc.), and by matching the flatness of the lower end face of the lower partition 4 with the upper end face of the test groove, the seal between the bottom opening of the fixing body 3 and the test groove can be achieved, thus maintaining the airtightness of the test groove.

[0049] Through the above solution, this application achieves modular replacement of the wear component 402, avoiding the overall disassembly and replacement of the fixed body 3, effectively reducing maintenance downtime in the testing of high-viscosity fluids and powder materials, while providing a flexible installation base for monitoring elements such as thermocouples, improving the reliability and service life of the friction tester in continuous testing tasks. Furthermore, it can completely discharge the tested material 5 after the friction test is completed.

[0050] Example 4 The test chamber has a vent 301 at its bottom, extending to the side. The vent 301 is a radially arranged through-hole, with its axis perpendicular to the axis of the test chamber. Located on the outer sidewall of the test chamber, the vent 301 allows for communication between the gas inside the test chamber and the outside environment through its radially through-hole structure.

[0051] The vent 301 allows trapped air in the chamber to escape smoothly during material filling in the test preparation phase; during the test, it provides a venting channel for thermally expanding gases or excess fluid. By timely removing gas from the chamber, the interference of air resistance on the shearing process is effectively eliminated, ensuring the compactness of the material filling and the stability of the pressure inside the test chamber, thereby guaranteeing the accuracy and repeatability of shear force measurement.

[0052] The vent 301 solves the measurement distortion problem caused by air resistance during the testing process of traditional closed friction pairs without affecting the normal testing process, thus optimizing the friction testing process for high-viscosity fluids and powder materials.

[0053] Example 5 The top surface of the protruding ridge 402 can be designed as a flat plane to provide a stable shear surface; or it can be designed as an upwardly arched arc surface, which can generate an upward component force on the material during rotation, promoting microcirculation of the material within the cavity and preventing material dead zones and deposition. Through the optimized design of the top surface of the protruding ridge 402, it is possible to ensure uniform transmission of shear force and suppress eddies and heat accumulation caused by sharp edges.

[0054] The two sides of the root of the protruding rib 402 have smooth chamfers, that is, the connection between the protruding rib 402 and the bottom of the test groove (or the lower partition plate 4) adopts a smooth transition structure. In particular, the chamfer on the side of the protruding rib 402 facing the rotating body 1 (the front edge) is greater than or equal to the chamfer on the side of the protruding rib 402 facing away from the rotating body 1 (the rear edge). This asymmetrical chamfer design can effectively guide the material flow, reduce the flow resistance, and at the same time enhance the fatigue resistance of the high stress area according to the friction load distribution law, significantly alleviating the stress concentration phenomenon at the root.

[0055] The side of the protruding ridge 402 facing the rotating body 1 is either a vertical surface or an inclined surface that gradually widens at the root of the ridge 402. The side of the ridge 402 facing the rotating body 1 refers to the surface of the ridge 402 facing the direction of motion of the rotating body 1. The inclined surface causes the ridge 402 to gradually widen towards the root, forming a wedge-shaped structure. This wedge-shaped structure enhances the gripping and squeezing effect of the ridge 402 on the material being tested, while significantly increasing the cross-sectional area at the root of the ridge 402, improving its structural strength and fracture resistance, and preventing damage due to stress concentration under high pressure.

[0056] like Figure 5 As shown in ~7, the profile shape of the cross section of the convex rib 402 can be rectangular, right-angled trapezoidal or wavy. Different cross section forms can be used to adapt to the test conditions and optimize the heat conduction path and structural stiffness.

[0057] As a specific implementation method, the solution of this application is implemented as follows: the top surface of the protruding ridge 402 is designed as an upward arched arc surface, and the cross-sectional profile adopts a wave shape to promote the smooth transition of high viscosity fluid during the shearing process.

[0058] As a specific implementation method, the solution of this application is implemented as follows: the two sides of the root of the protruding rib 402 are provided with rounded chamfers, wherein the chamfer size on the side facing the rotating body 1 is slightly larger than that on the side away from it. The side of the protruding rib 402 facing the rotating body 1 is adopted as an inclined surface, so that the protruding rib 402 gradually widens towards the root. The cross section is selected as a right trapezoid to enhance the bending strength under high load conditions.

[0059] The solution proposed in this application avoids local high-pressure points and maintains the continuity of the shear field by optimizing the geometry of the top surface of the convex ridge 402. Combined with the differentiated setting of the root chamfer, it disperses the load in the high-stress area. At the same time, the vertical or inclined structure facing the rotating body 1 guides the material to flow along a predetermined path to prevent stagnation and accumulation. Furthermore, the diverse selection of the cross-section balances thermal management and structural strength, so that the various geometric features work together in the continuous shearing process of high-viscosity fluids and powder materials, thereby ensuring uniform dissipation of frictional heat and stable transmission of shear force.

[0060] Through the above solution, this application effectively prevents the initiation of root cracks in the 402 protrusion, avoids material retention and local overheating, ensures the stability of the shearing process and the accuracy of frictional heat monitoring data, thereby significantly improving the reliability of test data and the service life of the equipment.

[0061] Example 6 The test groove has a circular cross-section, the rotating body 1 is a cylinder adapted to the test groove, and the sealing assembly is a set located between the annular surface of the test groove and the outer wall of the rotating body 1.

[0062] The test chamber has a complete circular cross-section, forming a continuous, single cylindrical torus. The matching rotating body is a solid cylinder. Because the rotating body 1 is a solid structure, it has high structural rigidity and a large flexural section modulus, resulting in minimal deformation under large overturning moments, ensuring operational stability under non-ideal alignment conditions. The structure is completely axisymmetric, with shear stress evenly distributed circumferentially, effectively avoiding local stress concentration and ensuring good consistency of measurement data. Only one sealing assembly is needed, located at the annular gap between the test chamber torus and the outer wall of the rotating body 1. By constructing a complete annular sealing interface, effective sealing and isolation of the test material is achieved. This sealing structure prevents lateral leakage of high-viscosity fluids or powder materials during shearing, maintains a stable pressure balance within the test chamber, and provides reliable sealing for continuous shearing.

[0063] Because the linear velocity of the central region of the flat-bottomed rotating body 1 approaches zero during rotation, the shearing effect on the material is very weak, easily forming a "dead zone" that does not participate in the main flow. The material in this region may not represent the true state of the overall material, leading to distortion in the measured coefficient of friction and temperature rise. Therefore, when the material being tested is a high-viscosity fluid that is prone to dead zones or has significant yield stress (such as pastes, polymer melts, slurries), the bottom surface of the solid rotating body 1 can be set as an inverted cone, as described in Example 1. The inverted cone structure forces the material to flow from the center to the edge under centrifugal force, thereby breaking the central dead zone, promoting the circulation and mixing of the material throughout the chamber (including the central region), and ensuring the uniformity and consistency of the shear field.

[0064] Furthermore, the inverted conical base promotes material circulation and prevents localized overheating. The active flow guided by the inverted conical shape facilitates heat convection and diffusion, resulting in a more uniform temperature field distribution and more reliable measurement data of frictional heat.

[0065] This embodiment is mainly applicable to high-viscosity fluids with good flowability, lubricating greases and other materials, as well as conventional testing scenarios that are sensitive to equipment costs and do not require a large shear area.

[0066] Example 7 The test groove has a circular cross-section, and the annular surface of the test groove includes an inner annular surface and an outer annular surface arranged concentrically, that is, the sidewall of the test groove is composed of two concentric cylindrical surfaces, an inner one and an outer one.

[0067] The rotating body 1 is a hollow cylinder with an open bottom that is adapted to the test groove. The inner wall and outer wall of the rotating body 1 correspond to the inner and outer ring surfaces of the test groove, respectively.

[0068] The sealing assembly comprises two sets: the first set is disposed between the outer wall of the rotating body 1 and the outer annular surface of the test groove, and the second set is disposed between the inner wall of the rotating body 1 and the inner annular surface of the test groove. Sealing units are independently configured for the inner and outer annular surfaces. The two sealing assemblies can employ identical or differentiated sealing structures, aiming to improve the system's environmental sealing performance under high-speed or high-viscosity conditions.

[0069] In this embodiment, the test groove has a circular cross-section. The circular cross-section and the hollow cylindrical rotating body 1 work together to form two concentric shearing regions, which increases the effective area of ​​the test region, expands the shearing range, and significantly enhances the constraint ability of the powder material in the annular space.

[0070] In this embodiment, a dual, concentric shearing and sealing interface is provided. Therefore, two independent sealing assemblies must be configured: the first set is located between the outer wall of the rotating body 1 and the outer annular surface of the test groove, and the second set is located between the inner wall of the rotating body 1 and the inner annular surface of the test groove. The two sealing assemblies are independently configured for the inner and outer annular surfaces, and their concentric layout enhances the system's sealing performance under high-speed conditions, effectively suppressing material leakage from multiple directions and ensuring the stability of the shearing process during long-term operation. This overall design, through optimized geometry and synergistic sealing mechanisms, provides a continuous and uniform shearing motion field for high-viscosity fluids and powder materials.

[0071] The hollow configuration of the rotating body 1, while occupying the same radial space, allows for simultaneous shearing through both inner and outer annular surfaces, resulting in a significantly increased effective shearing area compared to a solid configuration of the same diameter. This generates a larger torque signal, which is beneficial for improving measurement resolution. Furthermore, the symmetrical constraint of the inner and outer annular surfaces makes the rotating body function like a "floating" annular rotor, greatly enhancing the system's torsional stiffness and suppressing radial runout and vibration, making it more suitable for high-speed shearing conditions. The double-sealing system forms a closed annular test chamber, fundamentally eliminating the possibility of material leakage from both the inner and outer sides, making it particularly suitable for easily dusty powders and paste-like materials with a tendency to creep.

[0072] This embodiment is mainly applicable to powder materials, extremely high viscosity polymer melts, and precision testing scenarios requiring high torque output and high stability.

[0073] Example 8 The upper end of the annular surface of the test groove has a recessed mounting groove, and the bottom surface of the mounting groove is an inclined guide surface, which is inclined downward toward the inside of the test groove.

[0074] The sealing assembly includes a floating ring sealing structure, which comprises a floating ring 6 and an end cap 2. The floating ring 6 is an annular sealing element embedded in the mounting groove. The end cap 2 presses against the upper surface of the floating ring 6 and is fixed to the fixing body 3. The end cap 2 can press down on the floating ring 6 to press and hold the rotating body 1 tightly, forming a dynamic seal with the surface of the rotating body 1.

[0075] Specifically, the end cap 2 can be configured as a T-shaped structure. The lower part of the end cap 2 extends into the mounting groove to press down the float ring 6, which is used to adjust the sealing force of the float ring 6. The upper protruding edge of the end cap 2 is located above the fixing body 3. After assembly, the protruding edge of the end cap 2 can be fixed to the fixing body 3 by means of screws or the like.

[0076] To prevent the floating ring 6 from rotating with the rotating body 1 during installation, a locking structure is provided between the floating ring 6 and the mounting groove. This locking structure is a mechanical interlocking mechanism that constrains the circumferential displacement of the floating ring 6. It can be implemented as follows: a third positioning countersunk hole is formed at the bottom of the mounting groove, and a second positioning pin 7 is inserted into this hole. A fourth positioning countersunk hole 604, which mates with the second positioning pin 7, is provided on the lower surface of the floating ring 6. The locking structure can also be implemented using a keyway fit or a convex-concave interlocking method to ensure that the floating ring 6 remains circumferentially stable during the movement of the rotating body 1.

[0077] The mounting groove at the upper end of the test groove ring provides axial displacement space for the floating ring 6. Combined with the guide surface design where the bottom surface of the mounting groove slopes downward toward the inside of the test groove, when the end cap 2 applies pressure, the inclined guide surface guides the floating ring 6 to generate a radially inward component force, making the floating ring 6 tightly fit the surface of the rotating body 1. At the same time, when the temperature rises and causes the material to expand, the inclined guide surface allows the floating ring 6 to slide slightly axially, dynamically compensating for changes in the sealing gap. The end cap 2 presses against the upper surface of the floating ring 6 and, through its cooperation with the fixed body 3, presses down on the floating ring 6, ensuring sufficient clamping force while facilitating the adjustment and control of the sealing force.

[0078] Further preferably, a sealing ring 8 is provided between the lower surface of the end cap 2 and the upper surface of the fixing body 3. The sealing ring 8 is an annular sealing element, which can be implemented using an O-ring or a lip seal, and its purpose is to prevent the medium from leaking along the gap of the end cap 2. The sealing ring between the lower surface of the end cap 2 and the upper surface of the fixing body 3 blocks the external medium leakage path, thereby ensuring stable sealing performance during continuous shear testing.

[0079] When the test groove is circular, the mounting groove is only set in one ring on the annular surface of the test groove.

[0080] When the test groove is annular, the mounting slot needs to be set with one ring on both the inner and outer annular surfaces of the test groove. A floating ring 6 is set in each mounting slot, with two floating rings 6 arranged concentrically. The end cap 2 includes an annular outer end cap pressing on the outer floating ring 6 and a circular inner end cap pressing on the inner floating ring 6.

[0081] Example 9 The floating ring 6 includes a support portion 601 and a sealing portion 602. The support portion 601 is the basic load-bearing structure of the floating ring 6, made of 45# steel or cast carbon steel. Its function is to provide a stable mounting reference for the sealing portion 602, effectively resisting centrifugal loads and mechanical vibrations generated during rotation, and preventing changes in the sealing gap due to structural displacement. The sealing portion 602 is fixed to the support portion 601 and is made of Babbitt alloy, impregnated graphite, or carbon fiber composite material. It is used to directly contact the working surface of the rotating body 1 to form a dynamic sealing interface. The selected material has suitable wear resistance and self-lubricating properties, enabling it to form a good fit with the surface of the rotating body 1 and avoid adhesive wear, thereby establishing a stable contact seal and reducing the wear rate of the friction pair.

[0082] The surface of the sealing part 602 is provided with a spiral groove 603. The spiral groove 603 is a fluid guiding channel formed on the surface of the sealing part 602. It can be in the form of a single-head spiral or a multi-head spiral. The groove depth is designed to be 40%-60% of the axial dimension of the sealing part 602. The spiral direction of the spiral groove 603 from bottom to top is opposite to the rotation direction of the rotating body 1 (that is, if the rotating body 1 rotates clockwise, the spiral groove 603 rotates counterclockwise from bottom to top).

[0083] During the friction test, when the test material 5, subjected to shearing action, migrates outward along the sealing gap, it is influenced by the rotating body 1 to rotate clockwise. When it comes into contact with the spiral groove 603, it moves downward along the spiral groove 603 due to the direction of rotation of the spiral groove 603, generating a certain pressure. This pressure cancels out the upward movement of the test material 5, thereby reducing the height of the test material 5 overflowing upward along the side wall gap and increasing the accuracy of the friction measurement.

[0084] The reverse arrangement of the spiral grooves 603 pumps the tested material 5 inwards, guiding the high-viscosity fluid or powder material along the channels into the test tank. This generates continuous inward hydrodynamic pressure, actively pumping any media attempting to leak outwards back into the test tank, rather than relying solely on passive mechanical clamping force. This effectively inhibits material penetration in the circumferential gaps and maintains the continuity and stability of the shear field. Simultaneously, the floating ring 6 is subjected to an upward force, causing it to press tightly against the end cap 2, forming an end-face seal.

[0085] Through the above solution, this application effectively solves the leakage problem of high-viscosity fluids or powder materials in continuous shear testing, avoids shear field fluctuations and measurement data distortion caused by unstable sealing interfaces, and thus ensures the long-term stability of the test environment and the reliability of data during friction experiments.

[0086] Example 10 The sealing assembly includes a labyrinth seal structure, which includes turbulence-inducing teeth 203 disposed on the annular surface of the test groove. The turbulence-inducing teeth 203 are raised structures disposed on the annular surface of the test groove, and their cross-section can be rectangular. The turbulence-inducing teeth 203 have multiple rows, preferably 2-4 rows, arranged at axial intervals, which can be achieved using equal or unequal spacing. The turbulence-inducing teeth 203 extend circumferentially to form a circumferentially closed structure, meaning each row of turbulence-inducing teeth 203 is a continuous, gapless, full-circumferential raised ring, ensuring the continuity and integrity of the seal.

[0087] When the test material passes through the narrow gap between the turbulence-inducing teeth 203 and the rotating body 1, the flow channel suddenly contracts, creating a throttling effect, and the pressure energy of the test material is converted into kinetic energy. Subsequently, the flow channel suddenly expands in the cavity between the teeth, the flow velocity decreases, and the kinetic energy is dissipated into heat energy through eddy currents. Through the continuous throttling-expansion process of the multi-stage turbulence-inducing teeth 203, the pressure of the test material is significantly reduced step by step, thereby effectively blocking the axial leakage path of high-viscosity fluids or powder materials.

[0088] The turbulence-dissipating teeth 203 employ a circumferentially continuous seamless structure design, ensuring the integrity of the sealing ring surface and preventing the formation of local leakage channels. The axial spacing between each tooth provides ample expansion space for the medium, enhancing energy dissipation. This non-contact sealing structure is particularly suitable for sealing applications involving powder materials containing solid particles or extremely high-viscosity fluids, achieving effective sealing while avoiding wear issues of the sealing elements.

[0089] Through the above technical solution, the labyrinth sealing system established in this application can reliably maintain the sealing state of the test chamber, ensure the stability of the shear field during continuous testing, and provide the necessary environmental protection for the accurate measurement of the friction coefficient.

[0090] When the test groove is circular, the labyrinth seal structure is only provided on the circumferential surface of the test groove. When the friction pair includes end cap 2, the turbulence teeth 203 can be provided on the inner surface of end cap 2.

[0091] When the test groove is annular, the labyrinth seal structure needs to be set on both the inner and outer annular surfaces of the test groove. When the friction pair includes an inner end cover and an outer end cover, turbulence teeth 203 can be set on the inner surface of the outer end cover, and turbulence teeth 203 also need to be set on the outer surface of the inner end cover.

[0092] Example 11 The sealing assembly includes an air curtain sealing structure, which includes a pressure equalization groove 202 and a high-pressure air passage 201.

[0093] The equalizing groove 202 is formed on the annular surface of the test groove and located at the top of the test groove. The equalizing groove 202 is a continuous groove machined around the entire annular surface of the test groove, and the height and depth of the equalizing groove 202 are constant. Preferably, the width of the equalizing groove 202 is 2-3 mm and the depth is 1-1.5 mm. The inner surface of the equalizing groove 202 can also be polished to reduce gas flow resistance.

[0094] High-pressure air passages 201 are formed on the fixed body 3. There can be one or more high-pressure air passages 201, arranged evenly in a circumferential direction. Each high-pressure air passage 201 has a connecting section that communicates with the equalizing groove 202 and forms an angle of 30-60° with it. Specifically, the angle between the connecting section and the equalizing groove 202 refers to the angle between the centerline of the connecting section and the tangent direction of the equalizing groove 202. This angle can be set to specific values ​​such as 30°, 45°, or 60° to reduce turbulent impact during gas injection and ensure a smooth airflow transition.

[0095] By placing the equalizing groove 202 on the upper part of the test groove annular surface, the high-pressure gas can diffuse evenly along the annular surface before entering the sealing area, forming a stable pressure distribution. Simultaneously, the connecting section of the high-pressure gas channel 201 is connected to the equalizing groove 202 at a specific angle, allowing the gas to flow in along an oblique trajectory, effectively reducing turbulence and energy loss during injection. This structural design allows the gas to smoothly transition to the equalizing groove 202, thereby forming a uniform and durable gas film layer. The high-pressure gas flows through the equalizing groove 202 into the gaps between the floating ring 6 and the rotating body 1, and between the end cap 2 and the rotating body 1. The gas has a high pressure, allowing the material extruded during the operation of the rotating body 1 to reach pressure equilibrium more quickly in these gaps. This reduces the upward overflow height of the tested material 5 along the annular gap, thus maintaining a non-contact sealing state during the high-speed rotation of the rotating body 1, ensuring the continuity and stability of the shear environment, and improving the accuracy of friction measurement.

[0096] When the test groove is circular, the air curtain sealing structure is only provided on the circumferential surface of the test groove. When the friction pair includes end cap 2, the equalizing groove 202 can be provided on the inner surface of end cap 2.

[0097] When the test chamber is annular, the air curtain sealing structure needs to be provided on both the inner and outer annular surfaces of the test chamber. When the friction pair includes an inner end cover and an outer end cover, a pressure equalization groove 202 is provided on the inner surface of the outer end cover, and the high-pressure air passage 201 corresponding to the pressure equalization groove 202 is opened on the outer end cover; a pressure equalization groove 202 is provided on the outer surface of the inner end cover, and the high-pressure air passage 201 corresponding to the pressure equalization groove 202 is opened on the fixed body 3, and a channel for introducing high-pressure gas is opened at the axis of the fixed body 3, which is connected to each high-pressure air passage 201 on the fixed body 3 to realize gas supply.

[0098] This embodiment establishes a stable non-contact sealing environment by optimizing the airflow path and pressure distribution, effectively maintaining the sealing state of the grinding chamber, ensuring the stability of the shear field during long-term testing, and providing a reliable guarantee for the accurate measurement of the friction coefficient.

[0099] Example 12 The sealing assembly adopts a composite sealing structure, including the floating ring sealing structure, air curtain sealing structure, and labyrinth sealing structure described in Examples 8 to 11. The sealing assembly is provided with the labyrinth sealing structure, air curtain sealing structure, and floating ring sealing structure sequentially along the axial direction, forming a three-stage tandem sealing system.

[0100] Among them, the floating ring seal structure serves as the main seal, located at the bottom, and achieves basic sealing through mechanical clamping; the air curtain seal structure serves as the secondary seal, located above the floating ring seal structure, and forms an air curtain barrier by injecting high-pressure gas; the labyrinth seal structure serves as the auxiliary seal, located at the top, and enhances the overall sealing performance through multiple throttling effects.

[0101] During operation, the composite sealing system first blocks most of the test medium with the floating ring 6 seal; the air curtain seal further blocks possible leakage channels through pneumatic pressure, while also cooling and lubricating the floating ring 6 seal; and the labyrinth seal completely eliminates the risk of residual leakage through multi-stage pressure reduction. The three-stage sealing structure works together to form a complete sealing system from mechanical seal to non-contact seal.

[0102] This composite sealing solution is particularly suitable for complex working conditions involving high pressure, high speed, or solid particles. It can effectively address the sealing challenges of high-viscosity fluids and powder materials in continuous shear tests, ensuring the long-term stability of the shear environment and the reliability of measurement data during the test.

[0103] Example 13 A friction testing apparatus includes a fixed platform, a drive shaft, a loading shaft, a loading drive mechanism, a rotary drive mechanism, and a friction pair as described in any one of the above. The drive shaft is located above the fixed platform and perpendicular to it. The drive shaft is connected to a rotary drive mechanism that drives its rotation. The loading shaft is coaxial with the drive shaft, located below the fixed platform, and fixed to it. The loading shaft is connected to a loading drive mechanism that drives its lifting and lowering. The fixed body 3 of the friction pair is disposed on the fixed platform, and the rotating body 1 of the friction pair is connected to the lower end of the drive shaft via a coupling.

[0104] During testing, the loading shaft moves upwards continuously until the fixed body 3, containing the test material 5, contacts the rotating body 1 and is embedded in the test groove. A load is then applied, and the drive shaft rotates the rotating body 1 stably, continuously shearing the material. A pressure-torque composite sensor is installed between the fixed body 3 and the loading shaft to monitor the pressure and torque applied to the friction pair in real time during shearing, thereby calculating the material's internal friction coefficient. Simultaneously, a thermocouple embedded in the protrusion 402 monitors the frictional temperature rise. This system can simultaneously measure the friction coefficient and frictional heat under continuous shearing / friction conditions.

[0105] It should be noted that before measuring the internal friction coefficient of a material, the basic torque data of the system measured by the friction tester under no-load conditions should be obtained without adding any material. This data should be subtracted from the subsequent material measurement to improve the final measurement accuracy.

[0106] This technical solution successfully constructs a stable and continuous shear testing environment, solving the technical defects of traditional equipment that cannot adapt to the measurement of internal friction coefficient of high viscosity fluids and powder materials and the instability of the shear environment, and significantly improving the reliability and repeatability of test data.

[0107] The above are merely preferred embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A friction pair, characterized in that, include: The fixed body has a downwardly recessed test groove with a circular annular surface. The bottom of the test groove is provided with multiple upwardly protruding ridges, which are arranged radially and evenly around the center of the test groove. A rotating body capable of being embedded in a test slot and rotating; A sealing assembly for sealing the circumferential gap formed between the rotating body and the annular surface of the test groove.

2. The friction pair according to claim 1, characterized in that, It also includes a temperature measuring mechanism for measuring the temperature of the upper region of the protruding ridge inside the test tank, the temperature measuring mechanism comprising: At least one of the protruding ridges has a mounting hole, and a thermocouple is provided in the mounting hole; And / or, the fixed body is provided with a viewing window, and an infrared imager is provided outside the fixed body to measure the temperature of the upper area of ​​the protruding ridge through the viewing window.

3. The friction pair according to claim 1, characterized in that, The bottom of the test tank is provided with a removable lower partition, and the protruding rib is provided on the upper surface of the lower partition; The lower surface of the lower partition plate has a locking structure between it and the bottom surface of the test tank to restrict the rotation of the lower partition plate. The bottom of the fixing body has a top hole corresponding to the test slot.

4. The friction pair according to claim 1, characterized in that, The bottom of the test tank has an exhaust hole facing to the side.

5. The friction pair according to claim 1, characterized in that, The top surface of the protruding ridge is either a flat surface or an upwardly arched arc surface; The two sides of the root of the convex ridge have rounded chamfers, and the chamfer on the side of the convex ridge facing the rotating body is greater than or equal to the chamfer on the side of the convex ridge facing away from the rotating body. The side of the convex ridge facing the rotating body is either a vertical surface or an inclined surface that gradually widens towards the root of the convex ridge.

6. The friction pair according to claim 1, characterized in that, The test groove has a circular cross-section, the rotating body is a cylinder adapted to the test groove, and the sealing assembly is located between the annular surface of the test groove and the outer wall of the rotating body. Alternatively, the test groove has a circular cross-section, and the annular surface of the test groove includes an inner annular surface and an outer annular surface arranged concentrically. The rotating body is a hollow cylinder adapted to the test groove. The sealing assembly includes two sets, respectively disposed between the outer wall of the rotating body and the outer annular surface of the test groove, and between the inner wall of the rotating body and the inner annular surface of the test groove.

7. The friction pair according to claim 1, characterized in that, The upper end of the annular surface of the test groove has a recessed mounting groove, and the bottom surface of the mounting groove is an inclined guide surface, which is inclined downward toward the inside of the test groove. The sealing assembly includes a floating ring sealing structure, the floating ring sealing structure comprising: Floating rings, embedded in the mounting groove; and The end cap is pressed against the upper surface of the floating ring. The end cap and the fixed body can press down on the floating ring to make it hold the rotating body tightly.

8. The friction pair according to claim 7, characterized in that, The floating ring includes: Support section; and A sealing part is fixed to the support part and used to seal in contact with the rotating body. The surface of the sealing part is provided with a spiral groove, and the spiral direction of the spiral groove from bottom to top is opposite to the rotation direction of the rotating body.

9. The friction pair according to claim 1, characterized in that, The sealing assembly includes a labyrinth seal structure, which includes turbulence-inducing teeth disposed on the annular surface of the test groove; The turbulence-inducing teeth extend circumferentially to form a closed circumferential structure; The turbulence-inducing teeth have multiple channels, which are arranged at intervals along the axial direction.

10. The friction pair according to claim 1, characterized in that, The sealing assembly includes an air curtain sealing structure, the air curtain sealing structure comprising: An equalizing groove is formed on the annular surface of the test chamber and located at the top of the test chamber; and A high-pressure air passage is provided on a fixed body. The high-pressure air passage has a connecting section. The connecting section is connected to the pressure equalization groove and is set at an angle of 30-60° with the pressure equalization groove.

Images