A friction testing device for metallic materials

Abstract

This application discloses a friction testing device for metallic materials, comprising a frame, a hollow shaft torque motor, a friction section, a bearing section, and a force-changing section. The hollow shaft torque motor is mounted on the frame via its stator, and the inner cavity of the inner cylinder of the hollow shaft torque motor serves as a detection chamber. The friction drive motor of the friction section is mounted on the frame and connected to a friction seat, which extends into the detection chamber and houses a friction head. A spring is installed between the load plate and the bearing plate of the bearing section, and the external gear of the bearing plate meshes with the internal gear of the inner cylinder. A disc-shaped cam in the force-changing section drives the bearing plate to reciprocate vertically, thereby changing the pressure between the friction head and the sample. This application can perform various forms of friction tests, including rotary friction tests, circumferential rotary friction tests, constant pressure tests, and variable pressure tests, to simulate actual friction states as closely as possible, reduce the difference between experimental and actual data, and improve the consistency between experimental and actual data.

Description

Technical Field

[0001] This invention belongs to the field of wear resistance testing technology, specifically relating to a friction testing device for metallic materials. Background Technology

[0002] During use, the contact surfaces of metal materials will experience varying degrees of wear due to sliding. Over time, this wear will cause the gaps between components to widen. For components connected by detachable means such as bolts, friction will reduce the connection strength between the two components, affecting the stability of the equipment. In severe cases, it can lead to serious equipment failures or accidents. Therefore, the testing of the wear resistance of metal materials is crucial. With the rapid development of modern technology, metal material wear resistance testing equipment has also been improved.

[0003] Chinese patent CN210375940U discloses a metal material wear resistance testing device for easy clamping. In this device, a first motor drives a rack to slide on a slide rail via a first gear, pushing out a push column, thus facilitating the clamping of the metal material. A second motor, via the first and second racks, causes a friction head to perform intermittent reciprocating motion for friction, achieving energy savings. However, the friction head can only perform intermittent reciprocating motion in one direction, and the metal being tested is fixed on a base, making it difficult to adjust the pressure applied by the friction head. This presents certain limitations in practical use. Furthermore, during actual use, the pressure between components varies depending on the device's operating conditions, resulting in variable pressure friction. The friction intensity also varies at different locations of the same component. In existing testing equipment, friction tests typically involve constant-intensity friction on a designated area under constant pressure, failing to accurately simulate actual friction conditions, leading to significant discrepancies between experimental and actual data. Summary of the Invention

[0004] To improve the accuracy of friction testing in simulating actual friction conditions and enhance the consistency between test and actual data, this application proposes a friction testing device for metallic materials. The device includes a frame, a hollow shaft torque motor, a friction section, a load-bearing section, and a force-changing section. The hollow shaft torque motor includes a stator and a mover rotatably disposed inside the stator. The central axis of the hollow shaft torque motor extends vertically. A hollow shaft is fixedly mounted on the mover, and an inner cylinder is fixedly installed within the cavity of the hollow shaft, forming a detection chamber. The hollow shaft torque motor is fixedly mounted on the frame via its stator. The central axis of the hollow shaft torque motor extends vertically. The hollow shaft torque motor is a servo motor.

[0005] The friction unit includes a friction drive motor and a friction seat. The friction drive motor is fixedly mounted on the frame, and the friction seat is fixedly mounted on the output shaft of the friction drive motor. A friction head is detachably mounted on the friction seat, which is located inside the detection chamber. The friction motor can move horizontally on the frame and synchronously drive the friction head to move horizontally within the detection chamber.

[0006] The supporting part includes a loading plate, a load-bearing plate, a spring, and several reciprocating bolts. The loading plate is located above the load-bearing plate. The screws of the reciprocating bolts pass through the loading plate and the load-bearing plate from top to bottom and are screwed with limit nuts. The load-bearing plate and the reciprocating bolts are slidably connected. A spring is fitted on each bolt and is located between the loading plate and the load-bearing plate. The spring is a compression spring. An internal gear is provided on the inner wall of the inner cylinder, and an external gear is provided on the outer circumference of the load-bearing plate. The external gear meshes with the internal gear, and both the internal gear and the external gear extend vertically. The external gear can reciprocate up and down relative to the internal gear. The load-bearing plate is located below the inner cylinder, and a sample frame is fixed on the loading plate.

[0007] The force-changing unit includes a lifting mechanism, a cam frame, a disc cam, and a cam motor that drives the disc cam to rotate. The lifting mechanism is mounted on the frame, the cam frame is mounted on the lifting mechanism, the disc cam is rotatably mounted on the cam frame, and the cam motor is fixedly mounted on the cam frame with its output shaft connected to the disc cam. The curved profile of the disc cam slides against the lower surface of the support plate, and the disc cam is used to drive the support plate to reciprocate in the vertical direction.

[0008] The lifting mechanism can drive the cam frame to move up and down. When the lifting mechanism drives the cam frame to move down, the bearing part can move down synchronously and cause the sample frame to fall out of the detection chamber.

[0009] This application enables both fixed-position rotational friction tests and circumferential rotational friction tests, both of which can be conducted using constant pressure or variable pressure. The fixed-position rotational friction test involves maintaining a constant friction position of the friction head on the sample during the test, performing continuous friction tests on the same area. The circumferential rotational friction test involves changing the position of the friction head during the test. Two methods can be used: First, the friction head is eccentrically positioned relative to the central axis of the hollow shaft torque motor, keeping its position stationary. The mover of the hollow shaft torque motor drives the sample within the sample frame to rotate, thus forming an annular or circular friction area on the sample. Second, the friction head is also eccentrically positioned relative to the central axis of the hollow shaft torque motor. During the test, the mover of the hollow shaft torque motor drives the sample within the sample frame to rotate, simultaneously rotating the friction head and forming an annular or circular friction area on the sample.

[0010] When conducting tests with constant pressure, a lifting mechanism pushes the cam frame upwards, ensuring the pressure between the friction head and the specimen is at the set pressure, while the disc cam remains stationary. When conducting tests with variable pressure, the disc cam drives the support plate to move up and down, and a spring applies thrust to the support plate, thereby changing the pressure between the friction head and the specimen to simulate the actual friction state as closely as possible and reduce the difference between the test data and the actual data.

[0011] In addition, this application also has good safety features. Since the sample is located inside the detection chamber during the test, even if the sample is out of control, it will still be confined inside the detection chamber and will not fly out and cause harm to the surrounding operators and equipment, thus ensuring the safety of the test.

[0012] Furthermore, the friction unit also includes a top plate, which is fixedly mounted on the stator. An elongated hole is formed on the top plate, the center line of which extends radially along the hollow shaft torque motor and intersects the central axis of the hollow shaft torque motor. The friction drive motor is movably mounted on the top plate, and the output axis of the friction drive motor passes downward through the elongated hole.

[0013] This design allows for adjustment of the offset distance of the friction drive motor relative to the central axis of the hollow shaft torque motor during circumferential friction tests, to form friction areas of different shapes, such as annular or circular friction areas with excessive friction in the center.

[0014] Specifically, the lifting mechanism includes a piston cylinder, the cylinder barrel of which is fixedly mounted on the frame, and the piston rod extending vertically upwards. A cam frame is mounted on top of the piston rod. The piston cylinder can be a hydraulic cylinder, a pneumatic cylinder, or an electric cylinder. The piston cylinder allows for convenient adjustment of the position of the support plate and, via a spring, adjustment of the pressure between the friction head and the sample.

[0015] Furthermore, the lifting mechanism also includes several guide rods and a lifting plate, the lifting plate being fixedly installed on the top of the guide rods, and the cam frame being fixedly installed on the upper surface of the lifting plate; the frame includes a base plate and a middle plate, the middle plate being installed above the base plate via support columns, and a guide hole being opened on the middle plate corresponding to each guide rod, the guide rod being slidably inserted into the corresponding guide hole; the lifting plate is detachably installed on the top of the piston rod.

[0016] The lifting plate is designed to increase the installation area of ​​the cam frame, and the guide rod is designed to improve the stability of the lifting plate and also to improve the maintenance efficiency of the equipment. When the piston cylinder needs to be replaced, the guide rod can be used to keep the horizontal position of the disc cam, so there is no need to readjust the horizontal position of the disc cam when replacing the piston cylinder.

[0017] Furthermore, a limiting slide rod extending vertically downwards is installed at the bottom of the inner cylinder, and a sliding hole is opened on the support plate. The limiting slide rod slides into the sliding hole. When the sample frame is pushed downwards out of the detection chamber, and the distance between the top surface of the sample frame and the lowest point of the detection chamber is 3-10mm greater than the height of the sample, the limiting slide rod does not come out of the sliding hole. When the sample frame is pushed downwards out of the detection chamber, the entire support part has completely exited the detection chamber. Utilizing the limiting effect of the limiting slide rod and the supporting effect of the disc cam, the support part can still maintain a stable state when it is completely exited from the detection chamber, and will not tilt. When the piston rod of the piston cylinder extends upwards, it can smoothly insert the support plate into the detection chamber and make the external gear mesh with the internal gear. However, if the limiting slide rod is removed, when the support part is completely exited from the detection chamber, the contact between the support plate and the disc cam is a line contact, which cannot keep the entire support part stable, causing the support part to tilt.

[0018] Furthermore, the frame also includes four uprights fixedly mounted on the middle plate, arranged in a square. A hollow shaft torque motor is fixedly mounted on the top of the uprights via its stator. The load-bearing plate is circular, and the net distance between two adjacent uprights is greater than the outer diameter of the load-bearing plate. This design allows the space between two adjacent uprights to form a material channel, through which the loading plate, load-bearing plate, sample frame, and sample can all enter and exit for replacement.

[0019] Furthermore, the internal gear is integrally formed on the inner wall of the inner cylinder, or the internal gear is inserted into the inner wall of the inner cylinder using a key connection. When the internal gear is inserted into the inner wall of the inner cylinder using a key connection, a threaded cap is screwed onto the lower end of the inner cylinder. This threaded cap is used to prevent the internal gear from dislodging downwards from the inner cylinder. The threaded cap securely holds the internal gear on the inner cylinder, preventing it from dislodging downwards.

[0020] Furthermore, a monitor is installed inside the testing chamber to facilitate observation of the sample's pattern. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of an embodiment of this application.

[0022] Figure 2 for Figure 1 Enlarged view of section A.

[0023] Figure 3 This is a top view of the top plate. Detailed Implementation

[0024] The following provides a further description of the friction testing apparatus for metallic materials in this application. Please refer to [link / reference]. Figure 1 and Figure 2The friction testing device includes a frame 70, a hollow shaft torque motor 10, a friction section 20, a load-bearing section 40, and a force-changing section 50. The hollow shaft torque motor 10 includes a stator 110 and a mover 13 rotatably disposed inside the stator. The central axis 101 of the hollow shaft torque motor 10 extends vertically, and a hollow shaft 14 is fixedly mounted on the mover. In this embodiment, the stator 110 specifically includes a housing 11, an upper end cover 15, and a lower end cover 16. The housing 11 is cylindrical and extends vertically, and a winding 12 is provided on the inner side of the housing. The hollow shaft torque motor is a servo motor.

[0025] An upper flange 111 and a lower flange 112 are respectively provided at the upper and lower ends of the housing. The upper flange 111 is located above the lower flange 112. The upper end cover has a first flange corresponding to the upper flange, and a first bolt 152 fixes the first flange to the upper flange. The lower end cover has a second flange corresponding to the lower flange, and a second bolt 162 fixes the second flange to the lower flange, so that the upper end cover and the lower end cover are detachably installed on the top and bottom of the housing, respectively. The upper and lower ends of the housing are rotatably connected to the hollow shaft 14 via an upper angular contact bearing 151 and a lower angular contact bearing 161, respectively.

[0026] In this embodiment, an upper flange 113 is provided on the upper part of the outer peripheral surface of the hollow shaft 14, and the upper end cover 15 abuts against the hollow shaft 14 via the upper angular contact bearing 151; the upper end cover has an inwardly protruding abutting flange 153, the lower surface of which is a downward-facing stepped surface, the abutting flange 153 abuts against the upper side of the outer ring of the upper angular contact bearing via its lower surface, and the upper flange abuts against the lower side of the inner ring of the upper angular contact bearing.

[0027] A stepped portion 114 is provided at the lower end of the hollow shaft 14. The stepped portion is formed by the radial inward indentation of the outer circumferential surface of the hollow shaft. The stepped portion has a step surface facing downward. The lower end cover 16 abuts against the hollow shaft 14 via the lower angular contact bearing 161. The inner side of the lower end cover has an upward-facing pressing surface 164. The pressing surface is an upward-facing step surface. The pressing surface 164 presses against the lower side of the outer ring of the lower angular contact bearing, and the stepped portion 114 presses against the upper side of the inner ring of the lower angular contact bearing.

[0028] The inner cylinder 17 is fixedly mounted on the hollow shaft, and the inner cavity of the inner cylinder is formed as a detection cavity 120. The inner cylinder and the hollow shaft are coaxially arranged. Specifically, in this embodiment, a first metal key 18 is provided between the inner cylinder 17 and the hollow shaft 14.

[0029] The upper end of the inner cylinder extends upward beyond the top of the hollow shaft and then protrudes radially outward to form a connecting flange 171. A third bolt 172 fixes the connecting flange 171 to the upper part of the hollow shaft, allowing the inner cylinder to be detachably installed on the hollow shaft. The structure of the hollow shaft torque motor adopts existing mature technology. For parts not described in detail, reference to existing technology is sufficient, and further details are omitted.

[0030] The frame 70 includes a base plate 71 and a middle plate 72. The middle plate is mounted on top of the base plate via support columns 73. Four columns 74 are mounted on the middle plate in a square arrangement. A support ring 741 is welded to the top of the four columns. The support ring is annular. A fourth bolt 742 passes through the support ring 741 from bottom to top and is screwed onto the lower end cover 16, thereby fixing the stator to the support ring. This allows the hollow shaft torque motor to be fixedly mounted on the frame via its stator, that is, the hollow shaft torque motor to be fixedly mounted on the top of the columns via its stator.

[0031] The friction unit 20 includes a top plate 21, a friction drive motor 25, and a friction seat 23. The upper surface of the upper end cover 15 protrudes upward to form a support ring 154. The top plate 21 is detachably mounted on the top of the support ring by bolts, thus fixing the top plate to the stator, and consequently, indirectly fixing the friction drive motor to the frame via the stator. Please also refer to... Figure 3 An elongated hole 211 is formed in the top plate. This elongated hole extends radially along the hollow shaft torque motor and inwardly beyond the central axis 101 of the hollow shaft torque motor, such that the center line 213 of the elongated hole extends radially along the hollow shaft torque motor and intersects the central axis of the hollow shaft torque motor. For clarity, in Figure 3 In the diagram, the central axis 101 of the hollow shaft torque motor is represented by a small circle.

[0032] The friction drive motor is movably mounted on the top plate 21 using T-bolts 251, and the output axis of the friction drive motor passes downward through the elongated hole 211. Figure 2 The diagram only shows one T-bolt as an example. A bolt slot 212 is provided on each side of the elongated hole, extending parallel to the length of the hole. A total of four T-bolts are provided, with two T-bolts forming a group. Each group of T-bolts is inserted into a bolt slot. To move the friction drive motor, the nut on the T-bolt is loosened to adjust its position. When the friction drive motor moves along the elongated hole, it drives the friction head to move horizontally within the detection chamber. That is, the friction motor can move horizontally on the frame and simultaneously drive the friction head to move horizontally within the detection chamber. The length of the elongated hole is such that the central axis of the friction drive motor coincides with the central axis of the hollow shaft torque motor.

[0033] To facilitate observation of the wear condition of the sample inside the testing chamber and to record the test process, a monitoring instrument 26 is installed inside the testing chamber.

[0034] The friction shaft 22 is fixedly mounted on the output shaft of the friction drive motor via a coupling 221. A friction seat 23 is welded to the lower end of the friction shaft 22. A friction head 24 is fixedly mounted on the lower side of the friction seat 23 by bolts. The friction shaft 22 extends vertically downward into the detection cavity 120, so that both the friction seat and the friction head are located in the detection cavity 120.

[0035] The support unit 40 includes a loading plate 41, a load-bearing plate 42, a spring 45, and four reciprocating bolts 43. Both the loading plate 41 and the load-bearing plate 42 are circular and horizontally arranged. The loading plate is located above the load-bearing plate. The thread of each reciprocating bolt passes through the bolt holes on the loading plate and the load-bearing plate from top to bottom and is then screwed with a limiting nut 44, so that the limiting nut is located on the lower side of the load-bearing plate. The sample frame 49 is fixedly installed on the upper surface of the loading plate. The specific installation method of the sample frame 49 can adopt existing technology. Specifically, in this embodiment, the sample frame is screwed onto the bottom plate of the sample frame by three screws 413 passing through the loading plate from bottom to top. The purpose of fixing the sample frame is to prevent the sample frame from rotating relative to the loading plate during the test. Therefore, as long as the sample frame can be fixed on the loading plate and rotation of the sample frame relative to the loading plate can be prevented, the specific fixing method is not limited, as long as it is convenient to disassemble the sample frame.

[0036] A spring 45, a compression spring, is fitted onto the shank of each reciprocating bolt and is located between the carrying plate and the support plate. To maintain the flatness of the upper surface of the carrying plate 41, the bolt hole of the carrying plate corresponding to each reciprocating bolt is a stepped hole 411 with a large hole facing upwards. The bolt head 431 of the reciprocating bolt is accommodated in the large hole of the stepped hole, and the bolt head does not protrude upwards from the stepped hole. To stably hold the reciprocating bolt on the carrying plate, a locking nut 432 is screwed onto the shank of the reciprocating bolt. The locking nut is located between the carrying plate and the support plate and presses tightly against the lower surface of the carrying plate. In this embodiment, the spring is specifically a cylindrical helical compression spring. Since the inner diameter of the spring in this embodiment is only 2mm larger than the outer diameter of the reciprocating bolt shank, the two ends of the spring press against the lower surface of the locking nut and the upper surface of the support plate, respectively. It is understood that, in another embodiment, when the inner diameter of the selected spring is larger than the outer circle of the locking nut, the upper end of the spring can directly press against the lower surface of the carrier plate.

[0037] The lower inner wall of the inner cylinder 17 is radially recessed outward to form an annular expanded diameter portion 173. This annular expanded diameter portion 173 has a downward-facing stepped surface 174. The internal gear 31 is inserted into the annular expanded diameter portion 173 from bottom to top and presses against the stepped surface 174. A second metal key 312 is installed between the internal gear and the inner wall of the annular expanded diameter portion to allow the internal gear to rotate synchronously with the inner cylinder. In this embodiment, the internal gear is an internal gear ring. It can be understood that in another embodiment, the internal teeth can also be formed directly on the inner circumferential surface of the inner cylinder, i.e., the internal gear is integrally formed on the inner wall of the inner cylinder.

[0038] To prevent the internal gear from dislodging downwards from the inner cylinder, a hollow shaft 14 extends downwards from the lower end of the inner cylinder, and an external thread is provided on the outer wall of the lower end of the inner cylinder. A threaded cap 32 is screwed onto this external thread via its internal thread. The threaded cap 32 includes an annular wall 321 extending vertically and an annular cover plate 322 integrally formed at the lower end of the annular wall. An internal thread is formed on the inner circumferential surface of the annular wall. The upper surface of the annular cover plate presses against the lower end face of the internal gear, and the inner wall of the annular cover plate does not extend inwards beyond the root of the internal teeth 311 of the internal gear, so as to avoid interfering with the meshing of the external gear 412 and the internal gear. The threaded cap ensures that the internal gear is stably held on the inner cylinder, preventing it from dislodging downwards. A support plate is located below the annular cover plate 322.

[0039] An external gear 412 is provided on the outer peripheral surface of the carrier plate 41. The external gear meshes with the internal gear, and both the internal and external gears extend vertically, allowing the external gear to reciprocate up and down relative to the internal gear. In this embodiment, the external gear is specifically an external gear ring. It can be understood that in another embodiment, the external teeth can be directly machined on the carrier plate, that is, the external gear can be directly formed on the carrier plate.

[0040] The variable force unit 50 includes a lifting mechanism 510, a cam frame 54, a disc cam 56, and a cam motor 58 that drives the disc cam to rotate. In this embodiment, the lifting mechanism 510 includes a piston cylinder 51, a guide rod 52, and a lifting plate 53. Specifically, the piston cylinder in this embodiment is an electric cylinder. The cylinder barrel 511 of the electric cylinder is fixedly mounted on the middle plate, and the piston rod 512 of the electric cylinder extends vertically upwards. A threaded hole is provided on the lifting plate 53, and an external thread is provided on the top of the piston rod. The piston cylinder is screwed into the threaded hole of the lifting plate through its external thread, so that the lifting plate is detachably fixed to the top of the piston rod. The cam frame is welded to the upper surface of the lifting plate, so that the cam frame is mounted on the top of the piston rod. It is understood that in another embodiment, a hydraulic cylinder or a pneumatic cylinder can be used instead of an electric cylinder.

[0041] Four guide rods 52 are provided, with their tops screwed onto the lifting plate 53 using a threaded method, and the guide rods extending vertically. Corresponding to each guide rod 52, a guide hole 721 is provided on the middle plate, into which the guide rod slidably inserts. A clearance hole 711 is provided in the center of the base plate. When the piston rod moves the guide rod up and down via the lifting plate, the lower end of the guide rod can enter the clearance hole, and when the piston rod moves the guide rod down to the lowest position, the lower end of the guide rod does not extend beyond the lower surface of the base plate. The clearance hole is mainly provided to reduce the overall height of the equipment. It is understood that in another embodiment, the clearance hole can be omitted. When the clearance hole is omitted, when the piston rod moves the guide rod down to the lowest position, the lower end of the guide rod cannot touch the upper surface of the base plate.

[0042] The cam holder specifically includes two vertical plates extending in the vertical direction. A disc cam 56 is freely inserted between the two vertical plates. The two ends of the main shaft of the disc cam are rotatably mounted on a bearing seat 55. The two bearing seats are fixedly mounted on the top of a vertical plate by bolts, thereby rotatably mounting the disc cam on the cam holder.

[0043] A motor bracket 57 is welded to the outer wall of one of the upright plates. A cam motor 58 is fixedly mounted on the motor bracket, and the output shaft of the cam motor is connected to the main shaft of the disc cam. The curved profile of the disc cam slides against the lower surface of the support plate, and the disc cam is used to drive the support plate to reciprocate vertically. The piston rod can drive the cam frame to move up and down. When the piston rod drives the cam frame to move down to the lowest position, the bearing part can move down synchronously and cause the sample frame to fall out of the detection chamber.

[0044] When the sample frame detaches downwards from the detection chamber, the entire supporting part has completely exited the detection chamber. To prevent loss of control after the supporting part exits downwards from the detection chamber, in this embodiment, four limiting slide rods 61 are installed on the annular cover plate 322 of the threaded cover 32 using a threaded method. The four limiting slide rods extend downwards from the annular cover plate, and a sliding hole 62 is opened on the bearing plate corresponding to each limiting slide rod. The limiting slide rod is slidably inserted into the corresponding sliding hole. When the sample frame detaches downwards from the detection chamber, and the distance between the top surface of the sample frame and the lowest point of the detection chamber is 5mm greater than the height of the sample, the limiting slide rod does not disengage from the sliding hole. This allows the entire supporting part to maintain its original stable state under the pushing action of the piston cylinder and the restriction of the limiting slide rods during the process of installing or removing the sample from the sample frame. This allows the carrier plate carrying the sample frame to be reinserted into the detection chamber, and the external gear to mesh with the internal gear.

[0045] It is understood that in another embodiment, when the internal gear can be tightly installed on the inner cylinder without the possibility of slippage, or when the internal gear is directly formed on the inner cylinder, the threaded cover 32 can be eliminated. When the threaded cover is eliminated, the limiting slide rod 61 is installed at the lower end of the inner cylinder.

[0046] The specimen can enter and exit through the space between two adjacent columns, forming a material channel for the specimen. The specimen can be fixed within the specimen frame via this material channel, or removed from the specimen frame. Furthermore, the loading plate, load-bearing plate, and specimen frame can all be replaced through this material channel.

[0047] Since only four columns are installed, and these four columns are arranged in a square, the net distance between two adjacent columns is greater than the outer diameter of the load-bearing plate to facilitate the installation and maintenance of the load-bearing component. Because the load-bearing plate has the largest outer diameter in the load-bearing component, and the net distance between two adjacent columns is greater than the outer diameter of the load-bearing plate, other components of the load-bearing component can pass through the distance between two adjacent columns.

[0048] This embodiment enables both fixed-position rotational friction tests and circumferential rotational friction tests on the sample. Both tests can be conducted using either constant pressure or variable pressure. The fixed-position rotational friction test involves maintaining a constant friction position of the friction head on the sample, performing continuous friction tests on the same area. The circumferential rotational friction test involves changing the position of the friction head, which can be achieved using two methods. The first method involves setting the friction head eccentrically relative to the central axis of the hollow shaft torque motor, keeping the friction head stationary. The mover of the hollow shaft torque motor drives the sample within the sample frame to rotate, thus forming an annular or circular friction area on the sample. The second method also involves setting the friction head eccentrically relative to the central axis of the hollow shaft torque motor. During the test, the mover of the hollow shaft torque motor drives the sample within the sample frame to rotate, simultaneously rotating the friction head and forming an annular or circular friction area on the sample. In the accompanying drawings, the friction head is eccentrically positioned relative to the central axis of the hollow shaft torque motor. When conducting a constant pressure test, an electric cylinder pushes the support plate upward to maintain the pressure between the friction head and the sample at the set pressure, while the disc cam remains stationary. When conducting a variable pressure test, the disc cam drives the support plate to move up and down, and a spring applies a thrust to the bearing plate, thereby changing the pressure between the friction head and the sample to simulate the actual friction state as closely as possible.

[0049] When it is necessary to install or remove the sample, retract the piston rod of the piston cylinder downwards until the top surface of the sample frame is lower than the bottom surface of the threaded cap 32, and the distance between the top surface of the sample frame and the bottom surface of the threaded cap 32 is greater than the height of the sample. Then, the sample can be removed from the sample frame or installed inside the sample frame. A sample holder is installed inside the sample frame. The sample holder uses existing mature technology and will not be described in detail. The sample holder is not shown in the attached drawings.

Claims

1. A friction testing device for metallic materials, characterized in that, The device includes a frame, a hollow shaft torque motor, a friction section, a load-bearing section, and a force-changing section. The hollow shaft torque motor includes a stator and a mover rotatably disposed inside the stator. The central axis of the hollow shaft torque motor extends vertically. A hollow shaft is fixedly mounted on the mover, and an inner cylinder is fixedly installed in the inner cavity of the hollow shaft. The inner cavity of the inner cylinder forms a detection chamber. The hollow shaft torque motor is fixedly mounted on the frame via its stator. The central axis of the hollow shaft torque motor extends vertically. The hollow shaft torque motor is a servo motor. The friction unit includes a friction drive motor and a friction seat. The friction drive motor is fixedly mounted on the frame, and the friction seat is fixedly mounted on the output shaft of the friction drive motor. A friction head is detachably mounted on the friction seat, which is located inside the detection chamber. The friction motor can move horizontally on the frame and synchronously drive the friction head to move horizontally within the detection chamber. The supporting part includes a loading plate, a load-bearing plate, a spring, and several reciprocating bolts. The loading plate is located above the load-bearing plate. The screws of the reciprocating bolts pass through the loading plate and the load-bearing plate from top to bottom and are screwed with limit nuts. The load-bearing plate and the reciprocating bolts are slidably connected. A spring is fitted on each bolt and is located between the loading plate and the load-bearing plate. The spring is a compression spring. An internal gear is provided on the inner wall of the inner cylinder, and an external gear is provided on the outer circumference of the load-bearing plate. The external gear meshes with the internal gear, and both the internal gear and the external gear extend vertically. The external gear can reciprocate up and down relative to the internal gear. The load-bearing plate is located below the inner cylinder, and a sample frame is fixed on the loading plate. The force-changing unit includes a lifting mechanism, a cam frame, a disc cam, and a cam motor that drives the disc cam to rotate. The lifting mechanism is mounted on the frame, the cam frame is mounted on the lifting mechanism, the disc cam is rotatably mounted on the cam frame, and the cam motor is fixedly mounted on the cam frame with its output shaft connected to the disc cam. The curved profile of the disc cam slides against the lower surface of the support plate, and the disc cam is used to drive the support plate to reciprocate in the vertical direction. The lifting mechanism can drive the cam frame to move up and down. When the lifting mechanism drives the cam frame to move down, the bearing part can move down synchronously and cause the sample frame to fall out of the detection chamber.

2. The friction testing apparatus according to claim 1, characterized in that, The friction unit also includes a top plate, which is fixedly mounted on the stator. An elongated hole is formed on the top plate, the center line of which extends radially along the hollow shaft torque motor and intersects the central axis of the hollow shaft torque motor. The friction drive motor is movably mounted on the top plate, and the output axis of the friction drive motor passes downward through the elongated hole.

3. The friction testing apparatus according to claim 1, characterized in that, The lifting mechanism includes a piston cylinder, the cylinder barrel of which is fixedly mounted on the frame, the piston rod of which extends vertically upward, and a cam frame is mounted on the top of the piston rod.

4. The friction testing apparatus according to claim 3, characterized in that, The lifting mechanism also includes several guide rods and a lifting plate. The lifting plate is fixedly installed on the top of the guide rods, and the cam frame is fixedly installed on the upper surface of the lifting plate. The frame includes a base plate and a middle plate. The middle plate is installed above the base plate via a support column. For each guide rod, a guide hole is opened on the middle plate, and the guide rod is slidably inserted into the corresponding guide hole. The lifting plate is detachably installed on the top of the piston rod.

5. The friction testing apparatus according to claim 4, characterized in that, A limiting slide rod extending vertically downward is installed at the bottom of the inner cylinder. A sliding hole is opened on the load-bearing plate, and the limiting slide rod is slidably inserted into the sliding hole. When the sample frame is pushed downward out of the detection chamber, and the distance between the top surface of the sample frame and the lowest point of the detection chamber is 3-10 mm greater than the height of the sample, the limiting slide rod will not come out of the sliding hole.

6. The friction testing apparatus according to claim 4, characterized in that, The frame also includes four columns fixedly mounted on the middle plate. The four columns are arranged in a square. A hollow shaft torque motor is fixedly mounted on the top of the columns via its stator. The load-bearing plate is circular, and the net distance between two adjacent columns is greater than the outer diameter of the load-bearing plate.

7. The friction testing apparatus according to claim 1, characterized in that, The internal gear is integrally formed on the inner wall of the inner cylinder, or the internal gear is inserted into the inner wall of the inner cylinder by means of a key connection; when the internal gear is inserted into the inner wall of the inner cylinder by means of a key connection, a threaded cap is screwed on at the lower end of the inner cylinder, and the threaded cap is used to prevent the internal gear from falling out of the inner cylinder.

8. The friction testing apparatus according to claim 1, characterized in that, A monitoring device is installed inside the detection chamber.

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