A friction and wear test fixture with adjustable slip-roll ratio and its design method

Abstract

A friction and wear test fixture with an adjustable slip-roll ratio and its design method, belonging to the technical field of friction and wear testing machines, includes a connecting column, a screw, an upper specimen bracket, a bearing, upper and lower specimens, and a locking device. The upper part of the connecting column is connected to the sensor connecting rod of the friction and wear testing machine, and the lower part is matched with the annular protrusion of the upper specimen bracket. The upper specimen bracket includes a middle plate-like structure, an upper annular protrusion, and two left and right cantilevers with different lengths below. The lower end of the cantilever is provided with a locking device for clamping the upper specimen. During operation, the lower specimen rotates actively, and the upper specimen is driven to rotate by friction. The present invention is simple and reliable in operation. By adjusting the installation angle, the research on the wear degree of materials and surface coatings under different slip-roll ratios can be carried out on a disc-type friction and wear testing machine. The upper and lower specimens can be replaced according to needs. It has a simple structure, is easy to operate, is suitable for slip-rolling tests between various materials and surface coatings, has good economy, is convenient to install, and has a good fixing effect.

Description

Technical Field

[0001] The invention belongs to the technical field of friction and wear testing machines, and relates to a fixture with adjustable sliding-rolling ratio based on a disc-type friction and wear testing machine and a design method thereof. Background Technique

[0002] Friction is divided into rolling friction and sliding friction according to the form of motion. The friction coefficient of rolling friction is generally small, and it has been widely used in reducing friction. However, in some specific occasions, it is usually also desired to increase the frictional force to improve work efficiency, such as conveyor roller paths. In actual engineering, the motion form of the combination of sliding and rolling is very common. The interaction between materials causes wear on the surface gradually. Wear, as a form of failure, has an important impact on the accuracy, reliability and life of equipment. Therefore, it is of great significance to study the friction and wear mechanism and influence law of different sliding-rolling ratios on materials or surface coatings.

[0003] In the friction and wear experiments of different sliding-rolling ratios at home and abroad, a wheel-type friction and wear testing machine is often used, and the sliding-rolling ratio is adjusted by changing the rotation speed or size of the specimen. Usually, the friction and wear experiment of different sliding-rolling ratios between the upper and lower specimens cannot be completed on a disc-type friction and wear testing machine. Therefore, it is necessary to design a disc-type friction and wear test fixture with adjustable sliding-rolling ratio to solve the above technical problems. Summary of the Invention

[0004] Aiming at the difficulty of conducting different sliding-rolling ratio test studies on the existing disc-type friction and wear test platform and the lack of relevant research methods, the present invention patent provides a fixture with adjustable sliding-rolling ratio based on a disc-type friction and wear testing machine and a design method thereof. This method can realize the study of the wear degree of different sliding-rolling ratios on materials and surface coatings on the disc-type friction and wear testing machine by adjusting the installation angle. The upper specimen and the lower specimen can be replaced according to needs. The structure is simple and reliable, the operation is convenient, it is suitable for the sliding-rolling tests between various materials and surface coatings, has good economy, is convenient to install, and has good fixing effect.

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

[0006] A friction and wear test fixture with adjustable sliding-rolling ratio, comprising a connecting column 1, a screw 2, an upper specimen bracket 3, a bearing 4, an upper specimen 5, a locking device 6, and a lower specimen 7.

[0007] The upper part of the connecting column 1 is provided with a thread 12 for threaded connection with the sensor connecting rod of the friction and wear testing machine. The lower part of the connecting column 1 is circumferentially provided with a groove 11 for cooperating with the annular protrusion of the upper specimen bracket 3.

[0008] The upper specimen holder 3 described above includes a central plate-like structure, an annular protrusion 31 located above the plate-like structure, a left cantilever 33 and a right cantilever 32 located below the plate-like structure. Specifically: A plurality of platforms are evenly arranged along the circumferential direction on the outer wall of the annular protrusion 31, and threaded through holes 34 are provided at the positions of the platforms. The threaded through holes 34 are connected to the grooves 11 of the connecting column 1 by screws, realizing the connection between the annular protrusion 31 and the lower part of the connecting column; The lengths of the two cantilevers are different. The upper half of each of them is perpendicular to the plate-like structure, and the lower half of each makes a certain angle with the upper half. The two cantilevers are divided into a right cantilever 32 and a left cantilever 33 according to their positions (as Figure 2 ). Figure 3 ) At the bottom of the lower half of the right cantilever 32 and the left cantilever 33, there are cylindrical surface grooves 35 and grooves 36 and through holes 37 for installing the locking device 6 (as

[0009] )

[0010] Further, the locking device includes a hinge bolt 61, a fastening claw 62, a fastening bolt 63, and a locking hole 64. Specifically: The fastening claw 62 is crescent-shaped. Its inner wall fits with the outer wall of the bearing 4. There is a through hole for connecting the cantilever at the upper part and a locking hole 64 at the lower part. Two fastening claws 62 form a set of fastening claws, and a set of locking devices 6 contains two sets of fastening claws. In a set of locking devices 6, the two sets of fastening claws are symmetrically placed on both sides of the cantilever and are connected to the cantilever by the hinge bolt 61. (as Figure 4 )

[0011] A design method for a friction and wear test fixture with an adjustable slip-roll ratio includes the following steps:

[0012] (1) Design the upper specimen holder 3:

[0013] The inner wall of the upper annular protrusion 31 of the upper specimen holder 3 is connected to the lower end of the connecting column 1. A plurality of n platforms are evenly arranged along the circumferential direction on the outer wall of the annular protrusion 31. The threaded through holes 34 lead from the platforms on the outer wall of the annular protrusion to the inner wall of the annular protrusion, and the number of threaded through holes is n (generally 5 to 8); The upper specimen holder 3 and the connecting column 1 are connected by screws 2. The screws 2 pass through the grooves 11 and the threaded through holes 34. By adjusting the tightness of the screws 2, the upper specimen holder 3 can be sleeved on the lower part of the connecting column and freely rotate around the axis of the connecting column, represents the rotation angle; When the upper specimen holder 3 is in the initial position: The cone top corresponding to the frustum of the specimen body 51 coincides with the rotation center of the surface of the lower specimen 7

[0014] The length of the upper half of the left cantilever 33 of the upper specimen holder is h1, and the length of the upper half of the right cantilever is h2:

[0015] h2 = h1 + l·tan(θ1) (1)

[0016] Where: l is the distance between the two cantilevers, and θ1 is the angle (acute angle) between the upper and lower parts of the cantilever;

[0017] At the bottom of the cantilever 32 of the upper specimen holder 3, there is a cylindrical groove 33 with a diameter of d1; a locking device 6 is provided at the cylindrical groove 33.

[0018] (2) According to the specific implementation conditions of the friction and wear test fixture with adjustable slip-roll ratio, the upper specimen 5 and its installation method are designed as follows:

[0019] (a) The upper specimen 5 includes a specimen body 51 and a support shaft 52. The specimen body 51 is frustum-shaped, and its taper is:

[0020] (d4 - d3):l2 (2)

[0021] Where: d4 is the diameter of the lower bottom circle of the specimen body 51, d3 is the diameter of the upper bottom circle of the specimen body 51, and l2 is the height of the frustum of the specimen body 51;

[0022] (b) The upper specimen support shaft 52 is fixedly connected to the upper and lower bottom surfaces of the specimen body 51 respectively, and the diameter of the support shaft is d5:

[0023] d5 = d2 (3)

[0024] Where: d2 is the inner diameter of the bearing 4, and the upper specimen support shaft 52 is in interference fit with the inner diameter of the bearing 4;

[0025] (c) After the upper specimen 5 is fitted with the thrust bearing 4, it is snapped into the cylindrical groove 33 and fixed by the locking device 6. The specimen body 51 is located between the left cantilever 33 and the right cantilever 32, and the outer diameter of the thrust bearing is d1;

[0026] (d) After the upper specimen 5 is installed, the upper specimen body 51 can be brought into contact with the surface of the lower specimen 7 through the lifting and adjusting mechanism of the friction and wear testing machine. The contact type is line contact. Then, the relationship between d4, d3, l2, and θ2 is:

[0027]

[0028] Where: the angle θ2 is the angle between the axis of the upper specimen and the surface of the lower specimen; the relationship between θ1 and θ2 is:

[0029] θ1 = θ2 (5)

[0030] (e) In order to make the cone apex of the frustum of the specimen body 51 coincide with the rotation center of the surface of the lower specimen 7 at the initial position (such as Figure 6), the distance L between the axis of the connecting column 1 and the axis of the lower specimen 7:

[0031]

[0032] Among them, s represents the distance between the cantilever bending point and the axis of the column surface groove;

[0033] (3) According to the specific implementation method of the friction and wear test fixture with adjustable slip-roll ratio, the design method of the slip-roll ratio of the upper specimen 5 and the lower specimen 7 in the test is as follows:

[0034] The slip-roll ratio when the upper and lower specimens are in contact is defined as: ξ = 2(u1 - u2) / (u1 + u2), where u1 and u2 are the linear velocities of the lower specimen 7 and the upper specimen 5 at the contact point respectively; U = (u1 + u2) / 2 is called the "entrainment velocity". When ξ = 0, it is pure rolling, and when ξ = ±2, it is pure sliding;

[0035] (a) The linear velocity of the lower specimen 7 at the contact point is:

[0036] u1 = ω1·R (7)

[0037] Among them: ω1 is the rotational angular velocity of the lower specimen 7, and R is the distance from the rotation center of the lower specimen 7 to the contact point;

[0038] (b) The upper specimen 5 is driven by the frictional force of the lower specimen 7, and the linear velocity at the contact point of the upper specimen 5:

[0039]

[0040] Among them, is the angle of rotation of the upper specimen support 3 from the initial position

[0041] (c) The slip-roll ratio of the upper and lower specimens is expressed as:

[0042]

[0043] (d) In the initial state, ξ = 0, and the upper and lower specimens are in pure rolling; the upper specimen support rotates ξ = 2, and the upper and lower specimens are in pure sliding.

[0044] The friction and wear test fixture with adjustable slip-roll ratio designed by the present invention is used in cooperation with a disc-type friction and wear testing machine. By adjusting the angle of the upper specimen support, the technical purpose of testing the friction and wear performance of the upper and lower specimens under different slip-roll ratio conditions is achieved.

[0045] In the present invention, the lower specimen serves as a friction disc and rotates during the working process. It drives the upper specimen to roll along its axis through frictional force, accurately simulating the rolling-sliding friction process of materials or surface coatings: When the angle position of the fixture is adjusted to the initial position where the projection line of the axis of the upper specimen coincides with the diameter line of the friction disc of the lower specimen and fixed, the height of the fixture is controlled so that the upper specimen contacts the lower specimen. At this time, the rotation center on the surface of the lower specimen coincides with the apex of the cone of the main body of the upper specimen. When conducting a friction and wear experiment at this position, the linear velocities of the contact points of the upper and lower specimens are the same, and the upper specimen undergoes pure rolling; When the angle position of the fixture is adjusted to an acute angle with respect to the diameter line of the friction disc of the lower specimen and fixed, the height of the fixture is controlled so that the upper specimen contacts the lower specimen. When conducting a friction and wear experiment at this position, the linear velocity of the contact point of the upper specimen is less than that of the contact point of the lower specimen, and the upper specimen rolls and slides simultaneously; When the angle position of the fixture is adjusted to a right angle with respect to the diameter line of the friction disc of the lower specimen and fixed, the height of the fixture is controlled so that the upper specimen contacts the lower specimen. When conducting a friction and wear experiment at this position, the linear velocity of the contact point of the upper specimen is 0, and the upper specimen undergoes pure sliding.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The present invention does not require large-scale modification of the existing friction and wear testing machine. By simply replacing the upper specimen fixture, it is possible to conduct research on the wear degree of materials and surface coatings with different rolling-sliding ratios on a disc-type friction and wear testing machine. This fixture has a wide range of rolling-sliding ratios that can be tested, is convenient to replace, has a simple and reliable structure, and is cost-effective. Description of the Drawings

[0048] Figure 1 It is a schematic structural diagram of the present invention;

[0049] Figure 2 It is a front view structural schematic diagram of the present invention;

[0050] Figure 3 It is a schematic diagram of the cantilever structure of the present invention;

[0051] Figure 4 It is a partial structural schematic diagram of the locking device of the present invention;

[0052] Figure 5 It is a sectional structural schematic diagram of the present invention;

[0053] Figure 6 It is a schematic diagram of the pure rolling working state of the present invention.

[0054] In the figure: 1 connecting column; 11 groove; 12 thread; 2 screw; 3 upper specimen holder; 31 annular boss; 32 right cantilever; 33 left cantilever; 34 threaded through-hole; 35 cylindrical surface groove; 36 groove; 37 through-hole; 4 bearing; 5 upper specimen; 51 specimen body; 52 support shaft; 6 locking device; 61 hinge bolt; 62 fastening claw; 63 fastening bolt; 64 locking hole; 7 lower specimen. Specific embodiments

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described examples are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those of ordinary skill in the art without making creative efforts all fall within the protection scope of the present invention.

[0056] The specific implementation process of the design method of the friction and wear test fixture with adjustable slip-roll ratio of the present invention will be described in detail in combination with the accompanying drawings and technical solutions. Friction and wear on the material surface is one of the important reasons for the failure of mechanical components, and the slip-roll ratio is an important index affecting the friction and wear performance during the operation of mechanical components. To solve the difficulties that different slip-roll ratio friction and wear experimental studies cannot be completed on a disk friction and wear testing machine and the test results are inaccurate, this paper designs a disk friction and wear test fixture with adjustable slip-roll ratio, which does not require large-scale improvement of the existing disk friction and wear testing machine, only needs to replace the upper specimen fixture, is convenient to replace, has a simple and reliable structure, accurate data acquisition, and good economy.

[0057] The installation and debugging of the present invention before the test are divided into two steps: Step 1, threadedly connect the connecting column with the sensor connecting rod of the friction and wear testing machine, and fasten the upper specimen holder to the connecting column with screws; the support shafts on both sides of the upper specimen are in interference fit with the inner diameter of the bearings respectively, ensuring that the distances from the left and right bearings to the midpoint of the upper specimen are equal; open the fastening claws, and clamp the upper specimen with bearings between the cylindrical surface groove and the two fastening claws, and lock the fastening claws with the fastening bolts, so that the upper specimen has only the freedom of rotation around its axis; Step 2: Loosen the screws connecting the upper specimen holder and the connecting column, and rotate the upper specimen holder to the initial test position. Tighten the screws, make the upper and lower specimens contact through the lifting device of the friction and wear testing machine, apply the specified load, start the test, drive the upper specimen to rotate by the rotation of the lower specimen, and record data such as the contact force, the rotation speed of the lower specimen, and the wear depth; when replacing the specimen, only need to loosen the locking device, replace the upper specimen, adjust the lifting and angle of the upper specimen holder, and repeat Step 2 to test the friction and wear performance of the material surface under different slip-roll ratio conditions.

[0058] The specific implementation process of the present invention will be described in detail in combination with the accompanying drawings and technical solutions. In this embodiment, the friction coefficient μ between the upper and lower specimens is 0.6; specifically, the installation and test-related parameter calculations of the friction and wear test fixture with adjustable slip-roll ratio are as follows:

[0059] (1) The specific parameter calculations of the upper specimen holder are as follows:

[0060] (a) The number of through holes n in the upper annular protrusion of the upper specimen holder is 6;

[0061] (b) The upper specimen holder can be rotated clockwise, and the rotation angle At the initial position,

[0062] (c) The distance l between the left and right cantilevers is 29 mm, and the bending angle θ1 of the cantilever is 15°;

[0063] (d) The length of the upper half of the right cantilever of the upper specimen holder is h1 = 6.96 mm, and the length of the left cantilever:

[0064] h2 = h1 + l·tan(θ1) = 14.73 mm (1)

[0065] The diameter d1 of the cylindrical groove at the bottom of the cantilever of the upper specimen holder is 7 mm;

[0066] (2) The specific parameter calculations of the upper specimen are as follows:

[0067] (a) The diameter d4 of the lower bottom circle of the specimen main body is 22 mm, the diameter d3 of the upper bottom circle of the specimen main body is 12.45 mm, and the frustum height l2 of the specimen main body is 18 mm;

[0068] (b) The diameter of the support shaft of the upper specimen is d5 = 4 mm; the inner diameter d2 of the bearing is 4 mm; the outer diameter d1 of the bearing is 7 mm;

[0069] (c) According to the experimental requirements, the generatrix of the upper specimen main body is in contact with the surface of the lower specimen, so d4, d3, l2, θ2, θ1 satisfy:

[0070] θ2 = θ1 = 15° (2)

[0071]

[0072] The taper of the frustum of the specimen main body is:

[0073] (d4 - d3):l2 = 9.55:18 (4)

[0074] (e) The distance s between the bending point of the cantilever and the axis of the cylindrical groove is 5.19 mm. In order to make the apex of the cone corresponding to the frustum coincide with the rotation center of the lower specimen surface at the initial position, the distance L between the connecting column axis and the lower specimen axis:

[0075]

[0076] (3) The specific parameter calculation of the rolling and sliding ratio of the upper specimen and the lower specimen is as follows:

[0077] (a) The rotational angular velocity of the lower specimen ω1 = 10 rad / s, the distance from the rotation center to the contact point R = 65.2 mm, and the linear velocity at the contact is:

[0078] u1 = ω1·R = 652 mm / s (6)

[0079] (b) The linear velocity at the contact point of the upper specimen:

[0080]

[0081] (c) In the initial state, The rolling and sliding ratio of the upper and lower specimens:

[0082]

[0083] (d) When the upper specimen bracket rotates When ξ = 0.1436, the upper specimen rolls and slides; when the upper specimen bracket rotates When ξ = 2, the upper specimen is in pure sliding;

[0084] Working principle: The inner diameter of the bearing of the support shafts on both sides of the upper specimen is in interference fit, and the bearing is clamped into the cylindrical groove of the cantilever of the upper specimen bracket and fixed by a locking device, which can ensure the freedom of rotation of the upper specimen around its axis. The lower part of the connecting column is fitted with the inner wall of the annular protrusion on the upper part of the specimen bracket and fixed by six screws. The upper part of the connecting column is connected to the sensor part of the friction and wear testing machine. Before starting the test, first loosen the six screws, rotate the upper specimen fixture to the specified angle, and then fix it; when the angle position of the fixture is adjusted to the initial position When, control the height of the fixture so that the upper specimen contacts the lower specimen. At this time, the rotation center on the surface of the lower specimen coincides with the cone top of the corresponding circular table of the upper specimen body. When conducting the friction and wear experiment at this position, the linear velocities of the contact points of the upper and lower specimens are the same, and the upper specimen is in pure rolling; when the angle position of the fixture is adjusted to And fixed, control the height of the fixture so that the upper specimen contacts the lower specimen. When conducting the friction and wear experiment at this position, the linear velocity of the contact point of the upper specimen is less than that of the contact point of the lower specimen, and the upper specimen rolls and slides, and the rolling and sliding ratio is: When the angle position of the fixture is adjusted to Fix it and control the height of the fixture so that the upper specimen contacts the lower specimen. When the friction and wear experiment is carried out at this position, the linear velocity of the contact point of the upper specimen is 0, and the upper specimen is in pure sliding; the lower specimen serves as a friction disc and rotates during the working process, driving the upper specimen to roll along its axis through frictional force, accurately simulating the sliding-rolling friction process of materials or surface coatings. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0085] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A friction and wear test fixture with an adjustable slip-roll ratio, characterized in that The described friction and wear test fixture includes a connecting column (1), a screw (2), an upper specimen bracket (3), a bearing (4), an upper specimen (5), a locking device (6), and a lower specimen (7). The upper part of the connecting column (1) is connected to the sensor connecting rod of the friction and wear testing machine. The lower part of the connecting column (1) is circumferentially provided with a first groove (11) for mating with the annular protrusion (31) of the upper specimen bracket (3). The upper specimen bracket (3) includes a middle plate-like structure, an annular protrusion (31) located above the plate-like structure, a left cantilever (33) and a right cantilever (32) with different lengths located below the plate-like structure: the upper halves of the left cantilever (33) and the right cantilever (32) are perpendicular to the plate-like structure, the lower halves form an angle with the upper halves, and the bottoms of the right cantilever (32) and the left cantilever (33) are both provided with a cylindrical surface groove (35), a second groove (36) for installing the locking device (6), and a through hole (37). The upper specimen (5) includes a specimen main body (51) and support shafts (52) located on both sides thereof, wherein the specimen main body (51) is frustum-shaped; two locking devices (6) fix the bearing (4) through fastening bolts (63), and the bearing (4) is connected to the support shafts (52). The lower specimen (7) serves as a friction disk and drives the upper specimen (5) to roll along its axis through friction, simulating the sliding-rolling friction process. By adjusting the angle of the upper specimen bracket (3), the friction and wear performance of the upper specimen (5) and the lower specimen (7) under different sliding-rolling ratios is tested. When the fixture angle position is adjusted until the projection line of the axis of the upper specimen (5) coincides with the diameter line of the friction disk of the lower specimen (7) and fixed, the upper specimen (5) is brought into contact with the lower specimen (7), and the rotation center on the surface of the lower specimen (7) coincides with the cone apex of the main body of the upper specimen (5). When performing the friction and wear experiment at this position, the linear velocities of the contact points of the two specimens are the same, and the upper specimen (5) performs pure rolling. When the fixture angle position is adjusted until the projection line of the axis of the upper specimen (5) forms an acute angle with the diameter line of the friction disk of the lower specimen (7) and fixed, the upper specimen (5) is brought into contact with the lower specimen (7). When performing the friction and wear experiment at this position, the linear velocity of the contact point of the upper specimen (5) is less than the linear velocity of the contact point of the lower specimen (7), and the upper specimen (5) rolls and slides simultaneously. When the fixture angle position is adjusted until the projection line of the axis of the upper specimen (5) forms a right angle with the diameter line of the friction disk of the lower specimen (7) and fixed, the upper specimen (5) is brought into contact with the lower specimen (7). When performing the friction and wear experiment at this position, the linear velocity of the contact point of the upper specimen (5) is 0, and the upper specimen (5) performs pure sliding.

2. The friction and wear test fixture with adjustable sliding-rolling ratio according to claim 1, characterized in that, The described locking device includes a hinged bolt (61), a fastening claw (62), a fastening bolt (63), and a locking hole (64); the fastening claw (62) is crescent-shaped, its inner wall fits with the outer wall of the bearing (4), a through hole for connecting the cantilever is provided in the upper part, a locking hole (64) is provided in the lower part, and two fastening claws (62) form a set of fastening claws. A set of locking devices (6) includes two sets of fastening claws; in a set of locking devices (6), the two sets of fastening claws are symmetrically placed on both sides of the cantilever and connected to the cantilever through the hinged bolt (61).

3. An adjustable friction and wear test fixture with a sliding-rolling ratio, characterized in that The outer wall of the annular protrusion (31) is evenly provided with a plurality of platforms along the circumferential direction, and threaded through holes (34) are provided at the positions of the platforms. The threaded through holes (34) are connected to the first groove (11) of the connecting column (1) by screws, so as to realize the connection between the annular protrusion (31) and the lower part of the connecting column.

4. A design method for a friction and wear test fixture with an adjustable slip-roll ratio according to claim 1 or 2 or 3, characterized in that, It includes the following steps: 1) Design the upper specimen holder (3): The inner wall of the upper annular protrusion (31) on the upper specimen support (3) is connected to the lower end of the connecting column (1). The outer wall of the annular protrusion (31) is evenly provided with n platforms along the circumferential direction. The threaded through holes (34) lead from the platforms on the outer wall of the annular protrusion to the inner wall of the annular protrusion, and the number of the threaded through holes is n. The upper specimen support (3) and the connecting column (1) are connected by screws (2). The screws (2) pass through the first groove (11) and the threaded through holes (34). By adjusting the tightness of the screws (2), the upper specimen support (3) can be sleeved on the lower part of the connecting column and freely rotate around the axis of the connecting column. Indicates the rotation angle. When the upper specimen support (3) is in the initial position: the apex of the cone corresponding to the frustum of the specimen body (51) coincides with the rotation center of the surface of the lower specimen (7). At this time The upper half of the left cantilever (33) of the upper specimen holder has a length of h1, and the upper half of the right cantilever has a length of h2: h2 = h1 + l·tan(θ1) (1) Where: l is the distance between the two cantilevers, and θ1 is the included angle between the upper half and the lower half of the cantilever, which is an acute angle; A cylindrical groove (35) with a diameter of d1 is provided at the bottom of the cantilever (32) of the upper specimen holder (3); a locking device (6) is provided at the cylindrical groove (35); 2) According to the implementation conditions of the friction and wear test fixture with adjustable slip-roll ratio, the upper specimen (5) and its installation method are designed as follows: (a) The upper specimen (5) includes a specimen main body (51) and a support shaft (52). The specimen main body (51) is frustum-shaped, and its taper is: (d4 - d3):l2 (2) Where: d4 is the diameter of the lower bottom circle of the specimen main body (51), d3 is the diameter of the upper bottom circle of the specimen main body (51), and l2 is the height of the frustum of the specimen main body (51); (b) The upper specimen support shaft (52) is fixedly connected to the upper and lower bottom surfaces of the specimen main body (51) respectively, and the diameter of the support shaft is d5: d5 = d2 (3) Where: d2 is the inner diameter of the bearing (4), and the upper specimen support shaft (52) is in interference fit with the inner diameter of the bearing (4); (c) After the upper specimen (5) is fitted with the thrust bearing (4), it is clamped into the cylindrical groove (35) and fixed by the locking device (6). The specimen main body (51) is located between the left cantilever (33) and the right cantilever (32), and the outer diameter of the thrust bearing is d1; (d) After the upper specimen (5) is installed, the upper specimen main body (51) is brought into contact with the surface of the lower specimen (7) through the lifting adjustment mechanism of the friction and wear testing machine. The contact type is line contact. Then, the relationship between d4, d3, l2, and θ2 is: Where: the angle θ2 is the included angle between the axis of the upper specimen and the surface of the lower specimen; the relationship between θ1 and θ2 is: θ1 = θ2 (5) (e) In order to make the cone apex of the frustum of the specimen main body (51) coincide with the rotation center of the surface of the lower specimen (7) at the initial position, the distance L between the axis of the connecting column (1) and the axis of the lower specimen (7): Where, s represents the distance between the bending point of the cantilever and the axis of the cylindrical groove; 3) According to the implementation method of the friction and wear test fixture with adjustable slip-roll ratio, the design method of the test slip-roll ratio of the upper specimen (5) and the lower specimen (7) is as follows: The slip-roll ratio when the upper and lower specimens are in contact is defined as ξ, ξ = 2(u1 - u2) / (u1 + u2), where u1 and u2 are the linear velocities of the lower specimen (7) and the upper specimen (5) at the contact point respectively; U = (u1 + u2) / 2 is called the "entrainment velocity". When ξ = 0, it is pure rolling, and when ξ = ±2, it is pure sliding; (a) The linear velocity of the lower specimen (7) at the contact point is: u1 = ω1·R (7) Where: ω1 is the rotational angular velocity of the lower specimen (7), and R is the distance from the rotation center of the lower specimen (7) to the contact point; (b) The upper specimen (5) is driven by the frictional force of the lower specimen (7), and the linear velocity at the contact point of the upper specimen (5) is: Wherein, is the angle of rotation of the upper specimen holder (3) from the initial position, at this time (c) The slip-roll ratio of the upper and lower specimens is expressed as: (d) At the initial state, ξ = 0, and the upper and lower specimens are in pure rolling; the upper specimen bracket rotates ξ = 2, and the upper and lower specimens are in pure sliding.

5. The design method of a friction and wear test fixture with an adjustable slip-roll ratio according to claim 4, characterized in that, In the step 1), n is 5 to 8.

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