Vacuum high-low temperature rotating ball-disc friction testing machine

Abstract

The invention provides a vacuum high-low temperature rotating ball-disc friction testing machine, which relates to the technical field of material friction performance testing, and comprises a vacuum chamber, and a motion system, a ball sample system, a disc sample system, a high-low temperature cold trap system and an automatic sample changing system which are arranged in the vacuum chamber. The equipment can automatically replace a ball sample and a disc sample without damaging a vacuum environment. The equipment can simulate a high-vacuum and wide-temperature-range extreme environment, realizes automatic high-precision friction test, and is suitable for performance research of materials in the fields of aerospace and the like.

Description

Technical Field

[0001] This invention relates to the field of material friction performance testing technology, specifically to a ball-disc friction testing machine capable of accurately measuring the tribological properties of materials under extreme conditions of vacuum and high and low temperatures. Background Technology

[0002] In cutting-edge technology fields such as aerospace, lunar exploration, and deep space exploration, key moving components of spacecraft, satellites, and planetary surface probes (such as attitude adjustment mechanisms, solar panel deployment joints, and wheel drive systems) operate for extended periods in extreme environments characterized by near-vacuum conditions and drastic temperature variations. The tribological properties of the materials used in these components directly impact the reliability, lifespan, and mission success of the equipment. Therefore, accurately simulating vacuum and high / low temperature composite environments, and conducting tribological property tests on materials under these conditions, is crucial for the research, screening, and reliability assessment of novel space materials.

[0003] Currently, most common friction and wear testing machines on the market operate under normal pressure or low vacuum conditions, making it difficult to simultaneously achieve high vacuum (such as 10). -5 Precise control and simulation of loads on the order of Pa and over a wide range of high and low temperatures (e.g., -50℃ to +200℃) are required. Furthermore, existing equipment has shortcomings in test automation; for example, changing samples often requires disrupting the vacuum environment, leading to low test efficiency and difficulty in ensuring consistent test conditions. High-precision load and friction force measurements, especially achieving stable application and accurate measurement of minute loads in a vacuum environment, also present technical challenges.

[0004] Therefore, there is an urgent need to develop a rotating ball-disc friction testing machine that integrates high vacuum, wide temperature range control, high-precision loading and measurement, and automated sample changing functions to meet the urgent needs of cutting-edge fields for the study of the friction performance of materials in extreme environments. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention aims to provide a vacuum high and low temperature rotating ball-disc friction testing machine. This machine can accurately simulate extreme environments of high vacuum and a wide range of high and low temperatures, achieving high-precision load application and friction force measurement. It also possesses the capability for automatic replacement of ball and disk samples, thereby significantly improving testing efficiency and data reliability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a vacuum high and low temperature rotating ball-disc friction testing machine, including a vacuum chamber and a motion system, a ball sample system, and a disk sample system disposed within the vacuum chamber; The motion system includes a lifting mechanism and a translation mechanism. The translation mechanism is installed between a pair of symmetrically arranged lifting mechanisms, and the lifting mechanism is vertically installed on the side wall of the vacuum chamber. The ball sample system includes a ball sample loading mechanism and a force measuring mechanism. The ball sample loading mechanism is mounted on the translation mechanism and a ball sample clamp for holding the ball sample is mounted on the ball sample loading mechanism. The force measuring mechanism is mounted on the ball sample loading mechanism and is used to measure the loaded load and friction force in the ball-disc friction test. The disk sample system includes a disk sample driving mechanism and a disk sample fixture. The disk sample driving mechanism is installed at the bottom of the vacuum chamber, and the disk sample fixture is clamped on the top of the disk sample driving mechanism. A disk sample is installed on the top of the disk sample fixture, and the top surface of the disk sample contacts the spherical sample during the friction test.

[0007] Furthermore, the disk sample driving mechanism includes a rotating shaft, with a first mounting disk disposed on the top of the rotating shaft. Multiple first positioning pins are evenly arranged on the top of the first mounting disk in a circumferential direction. The lower end of the rotating shaft is connected to the output shaft of a first magnetohydrodynamic seal through a heat-insulating coupling. The first magnetohydrodynamic seal is disposed on the outer side of the bottom of the vacuum chamber. The input shaft of the first magnetohydrodynamic seal is driven by a first driving mechanism. The first driving mechanism includes a stepper motor, a driving pulley, and a driven pulley. The stepper motor is disposed on the outer side of the bottom of the vacuum chamber. The driving pulley and the driven pulley are respectively disposed on the input shaft of the stepper motor and the first magnetohydrodynamic seal. The driving pulley and the driven pulley are connected by a synchronous belt drive.

[0008] Furthermore, a disc sample is mounted on the top surface of the disc sample fixture, and several circular holes matching the first positioning pin are opened on its bottom surface. The bottom of the disc sample fixture is provided with an annular protrusion, and several self-locking holes are opened along the circumferential direction inside the annular protrusion. A set screw, a first spring, and a beveled pin are arranged from top to bottom in the self-locking holes. The set screw is threaded to the disc sample fixture. Several beveled holes are opened on the inner side of the annular protrusion, and the beveled holes are connected to the self-locking holes one by one. A first locking ball is provided in the beveled hole. The first locking ball contacts the lower beveled surface of the beveled pin and partially protrudes from the beveled hole under the pre-force of the first spring so as to lock the lower edge of the first disc.

[0009] Furthermore, the ball sample loading mechanism includes a crossbeam and a platform. The middle part of the crossbeam is rotatably mounted on the platform via a universal bracket. A ball sample clamp is installed at the left end of the crossbeam, and a counterweight adjustment mechanism is installed at the top of the right end of the crossbeam. The ball sample clamp includes a top rod, a loading rod, a locking sleeve, and a spherical sample. The spherical sample is placed inside the locking sleeve. The lower part of the loading rod is threadedly connected to the locking sleeve, and the lower end of the loading rod pushes part of the spherical sample out of the locking sleeve. The upper part of the loading rod has a cavity, and the top rod is slidably disposed in the cavity of the loading rod. A second spring is sleeved on the lower end of the top rod, and the lower end of the second spring abuts against the lower part of the cavity of the loading rod. Multiple oblique holes are evenly arranged circumferentially on the side wall of the cavity of the loading rod. A second locking ball is placed in the oblique hole. The second locking ball contacts the side wall of the top rod and, under the action of the pre-force of the second spring, partially protrudes from the oblique hole to precisely clamp the top of the crossbeam.

[0010] Preferably, the counterweight adjustment mechanism includes an adjustment frame mounted on a crossbeam, with a counterweight block slidably connected to the adjustment frame.

[0011] Preferably, the force measuring mechanism includes a first force measuring component for load measurement and a second force measuring component for friction force measurement. The first force measuring component includes a first force sensor and a first bearing. The first bearing is mounted on the first force sensor via a first bracket. The first force sensor is fixed on the platform. The first bearing is in rolling contact with the bottom surface of the right end of the crossbeam. The second force measuring component includes a second force sensor and a second bearing. The second bearing is mounted on the second force sensor via a second bracket. The second force sensor is fixed on the platform. The second bearing is in rolling contact with the rear side of the right end of the crossbeam.

[0012] Furthermore, the translation mechanism includes a first ball screw module, a first slider, and a second drive mechanism. The first slider is slidably mounted on the front side of the first ball screw module, and the platform is fixedly mounted on the front side of the slider. The second drive mechanism is used to drive the ball screw of the first ball screw module to rotate.

[0013] Furthermore, the lifting mechanism includes a lifting platform, a second slider, a second ball screw module, a third drive mechanism, and a second magnetohydrodynamic seal. The second ball screw module is vertically mounted on the inner side wall of the vacuum chamber, and the second slider is slidably mounted inside the second ball screw module. The first ball screw module is mounted on the top of the lifting platform, and the left and right ends of the lifting platform are respectively connected to the second slider on the same side. The structures of the second drive mechanism and the third drive mechanism are the same as those of the first drive mechanism. The stepper motor of the second drive mechanism is fixed to the first slider by a support. The stepper motors of the second magnetohydrodynamic seal and the third drive mechanism are both fixed to the top of the vacuum chamber. The driven pulley of the third drive mechanism is mounted on the input shaft of the second magnetohydrodynamic seal, and the output shaft of the second magnetohydrodynamic seal is coaxially connected to the ball screw of the second ball screw module.

[0014] Further, it also includes a high and low temperature cold trap system for controlling the temperature of the specimen in the vacuum chamber. The high and low temperature cold trap system includes a cold trap and a high and low temperature integrated machine. The cold trap is an annular structure with a cavity. The cold trap is fixed to the bottom surface of the vacuum chamber through a heat insulation material layer. The lower and upper parts of the annular inner wall of the cold trap are respectively rotationally installed with the middle part of the rotating shaft through a lower lip-shaped mechanical seal and an upper lip-shaped mechanical seal. The gap between the annular inner wall of the cold trap and the rotating shaft is filled with a solid lubricating and heat-conducting medium. A heat-conducting medium can be introduced into the cavity of the cold trap and is connected to the circuit of the high and low temperature integrated machine through a pipeline. The high and low temperature integrated machine is arranged outside the vacuum chamber.

[0015] Further, it also includes an automatic sample changing system. The automatic sample changing system includes a disk sample grabbing mechanism, a disk sample library, and a ball sample library. The disk sample grabbing mechanism is slidably installed on the first ball screw module. The disk sample library and the ball sample library are both arranged in the vacuum chamber. The disk sample library is used to store a number of disk sample toolings carrying different disk samples and, based on a motion system, cooperate with the disk sample grabbing mechanism to replace the disk sample tooling clamped on the top of the disk sample driving mechanism. The ball sample library is used to store a number of ball sample fixtures carrying different spherical samples and, based on the motion system, replace the ball sample fixture on the ball sample loading mechanism.

[0016] Preferably, the ball sample library is located on the right side of the disk sample system. It includes a chuck and a first magnetic force driven turntable. The first magnetic force driven turntable includes a rotor and a stator. The stator is fixed to the bottom surface of the vacuum chamber. The rotor is rotationally installed on the stator through a rotating shaft. A number of first electromagnets are evenly embedded in the stator in the circumferential direction. A number of permanent magnets corresponding to the second electromagnets are evenly embedded in the rotor in the circumferential direction, and the magnetic poles of each permanent magnet facing the second electromagnet are arranged in an alternating manner of N pole and S pole; the chuck is fixed to the top of the rotor. A number of clamping holes for placing the ball sample fixture are evenly opened in the chuck in the circumferential direction. A first electromagnet whose magnetic force acts on the ejector rod is arranged outside the clamping hole.

[0017] Preferably, the disk sample library is located on the left side of the disk sample system. It includes a second magnetic force driven turntable and a second disk loading device. The structure of the second magnetic force driven turntable is the same as that of the first magnetic force driven turntable. A number of columns are evenly arranged on the top of the rotor of the second magnetic force driven turntable in the circumferential direction. The upper ends of the columns are fixed with the second disk loading device. A number of second positioning pins are evenly arranged on the top of the second disk loading device. The second disk loading device is used to clamp the disk sample tooling.

[0018] Further, the disk sample grabbing mechanism includes a grabbing part and a third slider. The grabbing part is a "匚"-shaped structure with an upward opening. The rear side plate of the grabbing part is slidably arranged on the front side of the first ball screw module through the third slider. The third slider is located on the left side of the first slider. A "U"-shaped hole is opened on the middle bottom plate of the grabbing part, and a groove is opened in the "U"-shaped hole for clamping the outer edge boss of the disk sample tooling.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. This invention successfully constructs a system capable of accurately simulating vacuum (up to 10⁻⁶) by integrating a high-vacuum chamber, a high- and low-temperature cold trap system, a high-precision loading and force measuring mechanism, a servo / stepper motor driven precision motion system, and an automatic sample changing system. -5 This platform provides a friction testing environment capable of operating in extreme conditions (on the order of Pa) and over a wide temperature range (e.g., -50°C to +200°C). It addresses the urgent need in aerospace, deep space exploration, and other fields for reliable evaluation of the tribological properties of materials under extreme conditions.

[0020] 2. This invention employs a unique integrated design for loading and force measurement. Through an equal-arm beam lever structure with a universal support as the fulcrum, combined with two independent high-precision strain gauge force sensors (each equipped with rolling bearing contacts), the decoupling and high-precision measurement of the normal load and tangential friction force are achieved. During the loading process, the platform position is controlled by a lifting mechanism, and closed-loop control is implemented using feedback from the first force sensor, enabling precise and automatic load application with a wide range and good stability.

[0021] 3. This invention provides an automated sample changing system that operates in a vacuum environment. Through the coordinated use of a lifting and translational motion system, along with a spherical sample holder with magnetic locking / releasing function, a self-locking disc sample fixture, a magnetically driven rotary sample magazine, and a dedicated gripping mechanism, the system achieves automatic and accurate replacement of spherical and disc samples without disrupting the vacuum environment. This significantly improves experimental efficiency and avoids errors introduced by human intervention and time and energy losses caused by vacuum disruption.

[0022] 4. The transmission and sealing structure of this invention is stable and reliable. The rotating shaft adopts a magnetohydrodynamic seal, achieving efficient and zero-leakage transmission of rotational motion in a high vacuum environment. Lifting and translational movements are achieved using a stepper motor-driven ball screw module, with power introduced into the vacuum chamber through the magnetohydrodynamic seal, ensuring the accuracy and stability of the movement. High and low temperature control employs a structure combining an annular cold trap with a solid lubricating heat-conducting medium and a lip seal. While ensuring free rotation of the rotating shaft, it achieves efficient heat transfer from the cold trap to the sample plate, ensuring accurate and uniform sample temperature control.

[0023] 5. This invention adopts a modular design, facilitating manufacturing, installation, maintenance, and functional expansion. It can integrate high-precision sensors, data acquisition cards, and intelligent control algorithms to achieve fully automated test process control, data acquisition, safety monitoring and alarms, with a user-friendly human-machine interface. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a vacuum high and low temperature rotating ball-disc friction testing machine according to the present invention; Figure 2 This is a schematic diagram of the disk sample tooling and the high and low temperature cold trap. Figure 3 for Figure 1 A magnified view of a section at point A in the middle; Figure 4 Top view of the loading mechanism; Figure 5 This is a front sectional view of the automatic sample changing mechanism for spherical specimens. Figure 6 for Figure 5 Top view of the chuck; Figure 7 for Figure 5 Bottom view of the central rotor; Figure 8 for Figure 5 Top view of the middle stator; Figure 9 This is a front sectional view of the automatic sample changing mechanism for disc samples. Figure 10 This is a top view of the disc sample gripping mechanism; Reference numerals: 1-Vacuum chamber, 2-First drive mechanism, 201-Stepper motor, 202-Driving pulley, 203-Driven pulley, 204-Synchronous belt, 3-First magnetohydrodynamic seal, 4-Heat insulation coupling, 5-Rotating shaft, 6-First mounting plate, 7-First positioning pin, 8-Disc sample fixture, 9-Disc sample, 10-Setting screw, 11-First spring, 12-Beveled pin, 13-First locking ball, 14-Cold trap, 15-Lower lip mechanical seal, 16-Upper lip mechanical seal, 17-Solid lubricating heat-conducting medium, 18-Heat insulation material layer, 19-High and low temperature integrated machine, 20-Crossbeam, 21-Universal bracket, 22-Platform, 23-Adjusting frame, 24-Counterweight, 25-First force sensor, 26-First bearing, 27-First bracket, 28-Second force sensor, 29-Then Two supports, 30-Second bearing, 31-First slider, 32-Loading rod, 33-Top rod, 34-Second spring, 35-Second locking ball, 36-Locking sleeve, 37-Spherical sample, 38-First ball screw module, 39-Lifting platform, 40-Second drive mechanism, 41-Second slider, 42-Second ball screw module, 43-Third drive mechanism, 44-Second magnetohydrodynamic seal, 45-Chuck, 4501-Clip hole, 46-First electromagnet, 47-First magnetic drive turntable, 4701-Rotor, 4702-Stator, 4703-Rotating shaft, 4704-Permanent magnet, 4705-Second electromagnet, 48-Second magnetic drive turntable, 49-Column, 50-Second mounting plate, 51-Second positioning pin, 52-Gripper, 5201-Groove, 53-Third slider. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0026] See Figures 1 to 10 The vacuum high and low temperature rotating ball-disc friction testing machine provided in this embodiment is based on the construction of a closed and controllable extreme environment, and the realization of high-precision tribological testing and automated operation in this environment.

[0027] This embodiment of a vacuum high and low temperature rotating ball-disc friction tester includes a vacuum chamber 1 and a motion system, a ball sample system, and a disk sample system disposed within the vacuum chamber 1; the motion system includes a lifting mechanism and a translation mechanism, the translation mechanism being installed between a pair of symmetrically arranged lifting mechanisms, and the lifting mechanism being vertically installed on the inner wall of the vacuum chamber 1.

[0028] Specifically, the vacuum chamber 1 is the basic cavity of the entire equipment, made of 304 stainless steel with a thickness of 10mm. It is a cube-shaped structure designed to withstand pressure and temperature changes during the test. The entire cavity is welded using a vacuum brazing process to ensure excellent sealing and thermal insulation. The inner surface of the vacuum chamber 1 is mirror-polished to a roughness of Ra 0.2μm or less to reduce gas adsorption. Optionally, the vacuum chamber 1 is equipped with an observation window, an electrical feed terminal, and various pipeline interfaces (not fully shown in the figure). The interfaces use metal sealing, and the sealing gaskets are made of oxygen-free copper to ensure reliable sealing under high vacuum conditions. The vacuum chamber is evacuated to a high vacuum by a vacuum pump unit (not shown).

[0029] Specifically, the disk sample system is mainly used to drive the disk sample to rotate. It includes a disk sample driving mechanism and a disk sample fixture 8. The disk sample driving mechanism is installed at the bottom of the vacuum chamber 1, and the disk sample fixture 8 is clamped on the top of the disk sample driving mechanism. A circular disk sample 9 is installed on the top of the disk sample fixture 8. During the friction test, the top surface of the circular disk sample 9 contacts the spherical sample 37. The disk sample driving mechanism includes a rotating shaft 5. A first mounting disk 6 is set on the top of the rotating shaft 5. A plurality of first positioning pins 7 are evenly arranged on the top of the first mounting disk 6 in the circumferential direction. The lower end of the rotating shaft 5 is connected to the output shaft of the first magnetohydrodynamic seal 3 through a heat-insulating coupling 4. The heat-insulating coupling 4 effectively isolates the rotating shaft 5. The heat from the upper end is transferred to the first magnetohydrodynamic seal 3, which is located on the outer side of the bottom of the vacuum chamber 1. The input shaft of the first magnetohydrodynamic seal 3 is driven by the first drive mechanism 2. The first drive mechanism 2 includes a stepper motor, a drive pulley 202, and a driven pulley 203. The stepper motor is located on the outer side of the bottom of the vacuum chamber 1. The drive pulley 202 and the driven pulley 203 are respectively located on the input shaft of the stepper motor and the first magnetohydrodynamic seal 3. The drive pulley 202 and the driven pulley 203 are connected by a synchronous belt 204. The disc sample drive mechanism reliably transmits the rotational motion of the stepper motor to the vacuum chamber 1.

[0030] Specifically, a disc sample 9 is mounted on the top surface of the disc sample fixture 8, and several circular holes matching the first positioning pin 7 are opened on its bottom surface to ensure circumferential positioning. The bottom of the disc sample fixture 8 is provided with an annular protrusion, and several self-locking holes are opened in the annular protrusion along the circumferential direction. A set screw 10, a first spring 11, and a beveled pin 12 are arranged from top to bottom in the self-locking holes. The set screw 10 is threaded to the disc sample fixture 8. Several beveled holes are opened on the inner side of the annular protrusion, and the beveled holes are connected to the self-locking holes one by one. A first locking ball 13 is provided in the beveled hole. The first locking ball 13 contacts the lower beveled surface of the beveled pin 12, and under the pre-force of the first spring 11, it partially protrudes from the beveled hole to just lock the lower edge of the first mounting plate 6. By tightening the set screw 10 to preload the first spring 11, the inclined pin 12 moves downward, and its inclined surface pushes the first locking ball 13 outward, causing it to partially protrude from the inclined hole, thereby locking the lower edge of the first mounting plate 6 and achieving rapid locking of the tooling; during disassembly, the plate sample tooling 8 is pulled upward, and the edge of the first mounting plate 6 presses the first locking ball 13 inward, and the first spring 11 can be released by compressing the inclined surface.

[0031] Specifically, it also includes a high-low temperature cold trap 14 system for controlling the temperature of the sample inside the vacuum chamber 1. The high-low temperature cold trap 14 system includes a cold trap 14 and a high-low temperature integrated machine 19. The cold trap 14 is an annular structure with a cavity. The cold trap 14 is fixed to the bottom surface of the vacuum chamber 1 by a heat insulation material layer 18 to reduce heat loss. The lower and upper parts of the annular inner wall of the cold trap 14 are rotatably installed with the middle part of the rotating shaft 5 through a lower lip mechanical seal 15 and an upper lip mechanical seal 16, respectively. The gap between the annular inner wall of the cold trap 14 and the rotating shaft 5 is filled with a solid lubricating heat-conducting medium 17. The cavity of the cold trap 14 can be circulated with a heat-conducting medium and is connected to the high-low temperature integrated machine 19 through a pipe. The high-low temperature integrated machine 19 is located outside the vacuum chamber 1. This design ensures the free rotation of the rotating shaft 5 while establishing an efficient heat conduction path from the wall of the cold trap 14 to the rotating shaft 5 through the solid lubricating heat conduction medium 17. The heat is then conducted through the rotating shaft 5 to the first tray 6 and the tray sample fixture 8, and finally reaches the disc sample 9, achieving precise temperature control.

[0032] Specifically, the ball sample system is used to apply a normal load, install a ball sample, and measure the load and friction force; it includes a ball sample loading mechanism and a force measuring mechanism. The ball sample loading mechanism is mounted on a translation mechanism, and a ball sample clamp for holding a spherical sample 37 is mounted on the ball sample loading mechanism. The force measuring mechanism is mounted on the ball sample loading mechanism and is used to measure the applied load and friction force in the ball-disc friction test.

[0033] In some preferred embodiments of the present invention, the ball sample loading mechanism includes a crossbeam 20 and a platform 22. The middle part of the crossbeam 20 is rotatably mounted on the platform 22 via a universal bracket 21, and a ball sample clamp is mounted on the left end of the crossbeam 20. The universal bracket 21 is provided with bearings in both the horizontal and vertical directions, which can ensure that the crossbeam 20 can move left and right while moving up and down, thereby reducing the error of the test results. To ensure the flexibility of the universal bracket 21, its bearings use high-precision ceramic bearings.

[0034] In some preferred embodiments of the present invention, the ball sample fixture includes a top rod 33, a loading rod 32, a locking sleeve 36, and a spherical sample 37. The spherical sample 37 is placed inside the locking sleeve 36. The lower part of the loading rod 32 is threadedly connected to the locking sleeve 36, and the lower end of the loading rod 32 pushes part of the spherical sample 37 out of the locking sleeve 36. The upper part of the loading rod 32 has a cavity. The top rod 33 is slidably disposed in the cavity of the loading rod 32. A second spring 34 is sleeved on the lower end of the top rod 33. The lower end of the second spring 34 abuts against the lower part of the cavity of the loading rod 32. A plurality of oblique holes are evenly arranged circumferentially on the side wall of the cavity of the loading rod 32. A second locking ball 35 is placed in the oblique hole. The second locking ball 35 contacts the side wall of the top rod 33 and, under the pre-force of the second spring 34, partially protrudes from the oblique hole to precisely lock the top of the crossbeam 20, thereby realizing the rapid locking of the ball sample fixture. The ball sample holder is the key to automatic sample changing. When disassembly is required, a downward force (which can be achieved by external magnetic force) is applied to the top rod 33 to compress the second spring 34. The second locking ball 35 loses its support and retracts inward along the inclined hole, thus releasing the ball sample holder.

[0035] In some preferred embodiments of the present invention, a counterweight adjustment mechanism is installed at the top right end of the crossbeam 20 for initial balance adjustment. The counterweight adjustment mechanism includes an adjustment frame 23 disposed on the crossbeam 20, and a counterweight block 24 is slidably connected to the adjustment frame 23.

[0036] In some preferred embodiments of the present invention, the force measuring mechanism includes a first force measuring component for measuring normal load and a second force measuring component for measuring tangential friction force. The first force measuring component includes a first force sensor 25 and a first bearing 26. The first bearing 26 is mounted on the first force sensor 25 via a first bracket 27. The first force sensor 25 is fixed on the platform 22. The first bearing 26 is in rolling contact with the bottom surface of the right end of the crossbeam 20. The second force measuring component includes a second force sensor 28 and a second bearing 30. The second bearing 30 is mounted on the second force sensor 28 via a second bracket 29. The second force sensor 28 is fixed on the platform 22. The second bearing 30 is in rolling contact with the rear side of the right end of the crossbeam 20. Both sensors are fixed on the platform 22 and roll in contact with the crossbeam 20 via the bearings. The bearings transmit force to the sensors while avoiding constraints on the free movement of the crossbeam 20. The first force sensor 25 and the second force sensor 28 are S-type strain gauge sensors, employing an equal-arm beam 20 lever structure with a universal joint 21 as the fulcrum. The force value measured by the first force sensor 25 is the load applied by the spherical specimen 37 to the disk specimen 9. The frictional force between the spherical specimen 37 and the disk specimen 9 is transmitted to the second force sensor 28 with an equal force, thus the second force sensor 28 measures the frictional force during the test.

[0037] Specifically, the motion system realizes the spatial position adjustment of the spherical sample system and is the actuator for loading and automatic sample changing. It includes a vertical lifting mechanism and a horizontal translation mechanism. In some preferred embodiments of the present invention, the translation mechanism includes a first ball screw module 38, a first slider 31, and a second drive mechanism 40. The first slider 31 is slidably mounted on the front side of the first ball screw module 38, and the platform 22 is fixedly mounted on the front side of the slider. The second drive mechanism 40 is used to drive the ball screw of the first ball screw module 38 to rotate.

[0038] In some preferred embodiments of the present invention, the lifting mechanism platform includes a lifting platform 39, a second slider 41, a second ball screw module 42, a third drive mechanism 43, and a second magnetohydrodynamic seal 44. The second ball screw module 42 is vertically arranged on the inner wall of the vacuum chamber 1, and the second slider 41 is slidably installed inside the second ball screw module 42. A first ball screw module 38 is installed on the top of the lifting platform 39, and the left and right ends of the lifting platform 39 are respectively connected to the second slider 41 on the same side. The structures of the second drive mechanism 40 and the third drive mechanism 43 are the same as those of the first drive mechanism 2. The stepper motor of the second drive mechanism 40 is fixed to the first slider 31 by a support. The stepper motors of the second magnetohydrodynamic seal 44 and the third drive mechanism 43 are both fixed to the top outside of the vacuum chamber 1. The driven pulley 203 of the third drive mechanism 43 is installed on the input shaft of the second magnetohydrodynamic seal 44, and the output shaft of the second magnetohydrodynamic seal 44 is coaxially connected to the ball screw of the second ball screw module 42. The stepper motor of the second drive mechanism 40 is a vacuum stepper motor.

[0039] Specifically, it also includes an automatic sample changing system, which includes a disc sample gripping mechanism, a disc sample library, and a ball sample library. The disc sample gripping mechanism is slidably mounted on the first ball screw module 38. The disc sample library and the ball sample library are both located in the vacuum chamber 1. The disc sample library is used to store several disc sample fixtures 8 carrying different disc samples 9, and the disc sample fixtures 8 clamped on the top of the disc sample drive mechanism are replaced based on the motion system in conjunction with the disc sample gripping mechanism. The ball sample library is used to store several ball sample clamps carrying different ball samples 37, and the ball sample clamps on the ball sample loading mechanism are replaced based on the motion system.

[0040] In some preferred embodiments of the present invention, the ball sample library is located on the right side of the disk sample system, and includes a chuck 45 and a first magnetic drive turntable 47. The first magnetic drive turntable 47 includes a rotor 4701 and a stator 4702. The stator 4702 is fixed on the bottom surface of the vacuum chamber 1. The rotor 4701 is rotatably mounted on the stator 4702 via a rotating shaft 4703. A plurality of first electromagnets 46 are uniformly embedded in the stator 4702 in the circumferential direction. A plurality of permanent magnets 4704 corresponding to second electromagnets 4705 are uniformly embedded in the rotor 4701 in the circumferential direction. The magnetic poles of each permanent magnet 4704 facing the second electromagnet 4705 are arranged in an alternating manner of N pole and S pole. The chuck 45 is fixed to the top of the rotor 4701. A plurality of chuck holes 4501 for placing ball sample holders are uniformly opened in the circumferential direction on the chuck 45. The first electromagnets 46 that exert magnetic force on the top rod 33 are arranged outside the chuck holes 4501. When the first electromagnet 46 is energized, it generates a magnetic force to attract the push rod 33, thereby unlocking the ball sample holder. By sequentially energizing the second electromagnet 4705, a rotating magnetic field is generated, driving the rotor 4701 and chuck 45 to rotate in steps, thus sending the target ball sample holder to the sample changing position.

[0041] In some preferred embodiments of the present invention, the disk sample library is located on the left side of the disk sample system, and includes a second magnetic drive turntable 48 and a second mounting disk 50. The structure of the second magnetic drive turntable 48 is the same as that of the first magnetic drive turntable 47. A plurality of columns 49 are evenly arranged on the top of the rotor 4701 of the second magnetic drive turntable 48 in the circumferential direction. The upper end of the columns 49 is fixed to the second mounting disk 50. A plurality of second positioning pins 51 are evenly arranged on the top of the second mounting disk 50. The second mounting disk 50 is used to clamp the disk sample fixture 8.

[0042] In some preferred embodiments of the present invention, the disc sample gripping mechanism includes a gripping member 52 and a third slider 53. The gripping member 52 is an upward-opening "U"-shaped structure. The rear side plate of the gripping member 52 is slidably disposed on the front side of the first ball screw module 38 via the third slider 53. The third slider 53 is located to the left of the first slider 31. A "U"-shaped hole is opened on the middle bottom plate of the gripping member 52. A groove 5201 is opened in the "U"-shaped hole. The groove 5201 is used to engage the outer edge boss of the disc sample tooling 8.

[0043] In this embodiment, the automatic sample changing process is as follows: Replacing the ball sample: The motion system control platform 22 moves above the ball sample holder and descends, causing the shoulder of the loading rod 32 to land on the chuck 45. The first electromagnet 46 is energized, attracting the top rod 33 and releasing the second locking ball 35; the platform 22 rises, and the old ball sample holder disengages from the crossbeam 20; the first magnetic drive turntable 47 rotates, sending the new ball sample holder downwards; the platform 22 descends, causing the shoulder of the loading rod 32 of the new ball sample holder to contact the crossbeam 20, the first electromagnet 46 is de-energized, the top rod 33 moves upward under the action of the second spring 34, the locking ball pops out and locks, the platform 22 rises slightly, and the sample replacement is completed.

[0044] Changing the sample tray: The motion system controls the sample tray gripping mechanism to move above the sample tray fixture 8 in the working position and lower it, so that the outer edge boss of the sample tray fixture 8 enters the groove 5201. The gripping mechanism rises and lifts the sample tray fixture 8 from the first tray 6; the translational motion transports it to above the sample tray, lowers it and places it in the empty space of the second tray 50; the second magnetic drive turnstable 48 rotates, sending the sample tray fixture 8 containing the new disc sample 9 to the sample changing position, the gripping mechanism grips the new sample tray fixture 8, transports it and installs it on the first tray 6.

[0045] The parts not described in detail in this invention, such as vacuum pump units, sensor units (e.g., vacuum degree sensors, temperature sensors, proximity sensors, displacement sensors), data acquisition cards, industrial computers, motion control cards, control software, control algorithms, human-machine interfaces, and safety protection and alarm systems, are all configured and integrated using mature technologies in the field to achieve fully automatic intelligent operation of the equipment.

[0046] The working principle of this invention is as follows: Before the test, the designated spherical sample 37 and disc sample 9 are loaded using an automatic sample changing system; the vacuum chamber 1 is closed and evacuated to a high vacuum, and the high and low temperature integrated machine 19 is started, adjusting the cold trap 14 and the disc sample to the set temperature; the motion system control platform 22 descends, and closed-loop control is performed in conjunction with the feedback from the first force sensor 25 until the load applied to the spherical sample reaches the preset value; the first drive mechanism 2 is started, driving the disc sample to rotate at a set speed; during the friction process, the second force sensor 28 measures the friction force in real time, and the data acquisition system synchronously records parameters such as load, friction force, speed, temperature, and vacuum degree, calculating and recording the change of the friction coefficient over time. After the test, the sample can be automatically replaced for the next set of tests.

[0047] The vacuum high and low temperature rotating ball-disc friction testing machine of the present invention can realize the simulation of high vacuum environment, with an ultimate vacuum degree of 1×10⁻⁶. -5The pressure is below Pa, meeting the requirements for friction testing of materials sensitive to vacuum environments. It has a wide temperature control range, reaching -50℃ at the low end and 200℃ at the high end, with a temperature control accuracy within ±2℃, covering the testing needs of various materials. The ball sample loading mechanism is precise and reliable, with a loading force range from 1N to 50N and a loading accuracy better than ±0.1%f·s, ensuring stable and accurate normal loads on the ball-disc sample. The rotation speed is flexible, with the driving speed of the ball-disc rotation ranging from 1rpm to 3000rpm, and a speed control accuracy of ±1rpm, simulating relative motion speeds under different working conditions. It has a high-precision friction coefficient measurement capability, with a measurement range from 1N to 50N and a measurement accuracy of ±0.1%f·s, enabling real-time and accurate recording and feedback of changes in the tribological behavior of the material during the test.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. 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. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A vacuum high and low temperature rotating ball-disc friction testing machine, characterized in that, Includes a vacuum chamber (1) and a motion system, a ball sample system, and a disk sample system installed within the vacuum chamber (1); The motion system includes a lifting mechanism and a translation mechanism. The translation mechanism is installed between a pair of symmetrically arranged lifting mechanisms, and the lifting mechanism is vertically installed on the inner wall of the vacuum chamber (1). The ball sample system includes a ball sample loading mechanism and a force measuring mechanism. The ball sample loading mechanism is mounted on the translation mechanism. A ball sample clamp for holding a spherical sample (37) is clamped on the ball sample loading mechanism. The force measuring mechanism is mounted on the ball sample loading mechanism and is used to measure the loading load and friction force in the ball-disc friction test. The disk sample system includes a disk sample driving mechanism and a disk sample fixture (8). The disk sample driving mechanism is installed at the bottom of the vacuum chamber (1). The disk sample fixture (8) is clamped on the top of the disk sample driving mechanism. A disk sample (9) is installed on the top of the disk sample fixture (8). During the friction test, the top surface of the disk sample (9) contacts the spherical sample (37).

2. The vacuum high and low temperature rotating ball-disc friction testing machine according to claim 1, characterized in that: The disk sample driving mechanism includes a rotating shaft (5), a first mounting disk (6) is provided on the top of the rotating shaft (5), and a plurality of first positioning pins (7) are evenly arranged on the top of the first mounting disk (6) in the circumferential direction. The lower end of the rotating shaft (5) is connected to the output shaft of the first magnetohydrodynamic seal (3) through a heat-insulating coupling (4). The first magnetohydrodynamic seal (3) is located on the outer side of the bottom of the vacuum chamber (1). The input shaft of the first magnetohydrodynamic seal (3) is driven by a first driving mechanism (2). The first driving mechanism (2) includes a stepper motor, a driving pulley (202), and a driven pulley (203). The stepper motor is located on the outer side of the bottom of the vacuum chamber (1). The driving pulley (202) and the driven pulley (203) are respectively located on the input shaft of the stepper motor (201) and the first magnetohydrodynamic seal (3). The driving pulley (202) and the driven pulley (203) are connected by a synchronous belt (204).

3. The vacuum high and low temperature rotating ball-disc friction testing machine according to claim 2, characterized in that: The disc sample fixture (8) has a disc sample (9) mounted on its top surface. Several circular holes matching the first positioning pin (7) are opened on its bottom surface. The disc sample fixture (8) has an annular protrusion at its bottom. Several self-locking holes are opened along the circumferential direction inside the annular protrusion. The self-locking holes are provided with a set screw (10), a first spring (11), and a beveled pin (12) from top to bottom. The set screw (10) is threadedly connected to the disc sample fixture (8). Several beveled holes are opened on the inner side of the annular protrusion. The beveled holes are connected to the self-locking holes one by one. The beveled holes are provided with a first locking ball (13). The first locking ball (13) contacts the lower beveled surface of the beveled pin (12) and protrudes out of the beveled hole under the pre-force of the first spring (11) so as to just lock the lower edge of the first disc (6).

4. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 3, characterized in that: The ball sample loading mechanism includes a crossbeam (20) and a platform (22). The middle part of the crossbeam (20) is rotatably mounted on the platform (22) via a universal bracket (21). A ball sample clamp is installed at the left end of the crossbeam (20), and a counterweight adjustment mechanism is installed at the top right end of the crossbeam (20). The ball sample clamp includes a top rod (33), a loading rod (32), a locking sleeve (36), and a spherical sample (37). The spherical sample (37) is placed inside the locking sleeve (36), and the lower part of the loading rod (32) is threadedly connected to the locking sleeve (36). Furthermore, the lower end of the loading rod (32) pushes the spherical sample (37) out of the locking sleeve (36). The upper part of the loading rod (32) has a cavity, and the push rod (33) is slidably disposed in the cavity of the loading rod (32). A second spring (34) is sleeved on the lower end of the push rod (33). The lower end of the second spring (34) abuts against the lower part of the cavity of the loading rod (32). Multiple oblique holes are evenly arranged around the side wall of the cavity of the loading rod (32). A second locking ball (35) is placed in the oblique hole. The second locking ball (35) contacts the side wall of the push rod (33). Under the pre-force of the second spring (34), part of the oblique hole protrudes to fit precisely into the top of the crossbeam (20). The counterweight adjustment mechanism includes an adjustment frame (23) mounted on the crossbeam (20), and a counterweight block (24) is slidably connected to the adjustment frame (23). The force measuring mechanism includes a first force measuring component for load measurement and a second force measuring component for friction force measurement. The first force measuring component includes a first force sensor (25) and a first bearing (26). The first bearing (26) is mounted on the first bracket (27). The first force sensor (25) is fixed on the platform (22). The first bearing (26) can roll contact with the bottom right end of the crossbeam (20). The second force assembly includes a second force sensor (28) and a second bearing (30). The second bearing (30) is mounted on the second force sensor (28) through a second bracket (29). The second force sensor (28) is fixed on the platform (22). The second bearing (30) can roll contact with the rear right end of the crossbeam (20).

5. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 4, characterized in that: The translation mechanism includes a first ball screw module (38), a first slider (31), and a second drive mechanism (40). The first slider (31) is slidably mounted on the front side of the first ball screw module (38), and the platform (22) is fixedly mounted on the front side of the slider. The second drive mechanism (40) is used to drive the ball screw of the first ball screw module (38) to rotate. The lifting mechanism includes a lifting platform (39), a second slider (41), a second ball screw module (42), a third drive mechanism (43), and a second magnetohydrodynamic seal (44). The second ball screw module (42) is vertically mounted on the inner wall of the vacuum chamber (1), and the second slider (41) is slidably mounted on the inner side of the second ball screw module (42). The lifting platform (39) is fixedly mounted on the front side of the slider. 39) The first ball screw module (38) is installed on the top. The left and right ends of the lifting platform (39) are connected to the second slider (41) on the same side. The structures of the second drive mechanism (40) and the third drive mechanism (43) are the same as those of the first drive mechanism (2). The stepper motor of the second drive mechanism (40) is fixed on the first slider (31) by a support. The stepper motors of the second magnetohydrodynamic seal (44) and the third drive mechanism (43) are fixed on the top outside the vacuum chamber (1). The driven pulley (203) of the third drive mechanism (43) is installed on the input shaft of the second magnetohydrodynamic seal (44). The output shaft of the second magnetohydrodynamic seal (44) is coaxially connected to the ball screw of the second ball screw module (42).

6. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 5, characterized in that: It also includes a high and low temperature cold trap (14) system for controlling the temperature of the sample in the vacuum chamber (1). The high and low temperature cold trap (14) system includes a cold trap (14) and a high and low temperature integrated machine (19). The cold trap (14) is an annular structure with a cavity. The cold trap (14) is fixed to the bottom surface of the vacuum chamber (1) by a heat insulation material layer (18). The lower and upper parts of the annular inner wall of the cold trap (14) are rotatably installed with the middle part of the rotating shaft (5) through a lower lip mechanical seal (15) and an upper lip mechanical seal (16), respectively. The gap between the annular inner wall of the cold trap (14) and the rotating shaft (5) is filled with a solid lubricating heat-conducting medium (17). The cavity of the cold trap (14) can be circulated with a heat-conducting medium and is connected to the high and low temperature integrated machine (19) through a pipe. The high and low temperature integrated machine (19) is set outside the vacuum chamber (1).

7. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 6, characterized in that: It also includes an automatic sample changing system, which includes a disc sample gripping mechanism, a disc sample library, and a ball sample library. The disc sample gripping mechanism is slidably mounted on the first ball screw module (38). The disc sample library and the ball sample library are both located in the vacuum chamber (1). The disc sample library is used to store several disc sample fixtures (8) carrying different disc samples (9), and the disc sample fixtures (8) clamped on the top of the disc sample drive mechanism are replaced based on the motion system in conjunction with the disc sample gripping mechanism. The ball sample library is used to store several ball sample clamps carrying different ball samples (37), and the ball sample clamps on the ball sample loading mechanism are replaced based on the motion system.

8. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 7, characterized in that: The spherical sample library is located on the right side of the disk sample system, and it includes a chuck (45) and a first magnetic drive turntable (47). The first magnetic drive turntable (47) includes a rotor (4701) and a stator (4702). The stator (4702) is fixed on the bottom surface of the vacuum chamber (1). The rotor (4701) is rotatably mounted on the stator (4702) through a rotating shaft (4703). A number of first electromagnets (46) are evenly embedded in the stator (4702) in the circumferential direction. A number of permanent magnets (4704) corresponding to the second electromagnets (4705) are evenly embedded in the rotor (4701) in the circumferential direction, and the magnetic poles of each permanent magnet (4704) facing the second electromagnets (4705) are arranged in an alternating manner of N poles and S poles; the chuck (45) is fixed on the top of the rotor (4701). A number of card holes (4501) for placing ball sample jigs are evenly opened in the chuck (45) in the circumferential direction. A first electromagnet (46) whose magnetic force acts on the ejector rod (33) is arranged outside the card hole (4501).

9. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 8, characterized in that: The disk sample library is located on the left side of the disk sample system, and it includes a second magnetic drive turntable (48) and a second mounting plate (50). The structure of the second magnetic drive turntable (48) is the same as that of the first magnetic drive turntable (47). A number of columns (49) are evenly arranged on the top of the rotor (4701) of the second magnetic drive turntable (48) in the circumferential direction. The upper ends of the columns (49) are fixed with the second mounting plate (50). A number of second positioning pins (51) are evenly arranged on the top of the second mounting plate (50). The second mounting plate (50) is used for clamping the disk sample tooling (8).

10. A vacuum high and low temperature rotating ball-disc friction testing machine according to claim 8, characterized in that: The disk sample grasping mechanism includes a grasping member (52) and a third slider (53). The grasping member (52) is a "C"-shaped structure with an upward opening. The rear side plate of the grasping member (52) is slidably arranged on the front side of the first ball screw module (38) through the third slider (53). The third slider (53) is located on the left side of the first slider (31). A "U"-shaped hole is opened on the middle bottom plate of the grasping member (52). A groove (5201) is opened in the "U"-shaped hole, and the groove (5201) is used for clamping the outer edge boss of the disk sample tooling (8).

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