CN111272535B - Fretting sliding composite friction and wear test system and operation method thereof - Google Patents

Abstract

The invention relates to a fretting sliding compound friction and wear test system, comprising a support device, a pressure loading device, a three-dimensional force sensor, a fretting and sliding driving device, a precision clamping device, a measuring device, a friction pair unit, a data acquisition card and a computer control system; coordinate through the computer control system, so as to output in real time the wear performance of the friction pair under various load sizes, friction force frequencies and vibration displacement amplitudes; the test system realized by the invention can well simulate the human body and industrial In the application, the actual motion mode of many friction pairs is fretting and sliding composite superposition. At the same time, the test system can carry out the test load, lubrication conditions, sliding speed and speed of sliding friction, and fretting amplitude and frequency of fretting friction. Setting, friction and wear tests in pure fretting and pure sliding modes can be performed.

Description

A fretting sliding composite friction and wear test system and its operation method

technical field

The invention relates to a composite friction and wear test system, in particular to a fretting sliding composite friction and wear test system.

Background technique

Fretting friction refers to the reciprocating motion of the contact surface with a very small amplitude of micrometer or even nanometer, which usually occurs between approximately static contact interfaces caused by fatigue load, mechanical vibration, electromagnetic vibration or thermal cycle, etc. Hidden, but the danger is huge. The fretting will cause damage to the contact surface of the material, resulting in cracks, and even lead to the failure of the entire system; sliding friction means that when two objects in contact with each other have a relative motion or relative motion tendency, there is always a relationship between the two objects in contact with each other. The amount that resists this relative movement or tendency to relative movement is usually on the order of at least millimeters.

In human and industrial applications, the wear patterns of contact surfaces are not single, but varied. For the screws on the machine tool, the wear form is mainly fretting wear. For guide rails, the main form of wear is sliding. Fretting sliding compound friction is also very common. For example, the human elbow joint has fretting during small movements, and slips during large movements, causing its wear in the form of fretting and sliding. At the same time, high-speed trains, thermal power and nuclear power equipment, military and civil aviation equipment, modern cable-stayed bridges and suspension bridges, transmission cables and offshore oil extraction equipment also have a large number of fretting sliding composite friction and wear phenomena.

Due to the fretting, the contact surface of the material will be damaged and cracks will occur; at the same time, under the magnification of the larger amplitude of sliding friction, the cracks will further increase. Therefore, the damage caused by the fretting-sliding compound friction and wear form is even greater than that of the single friction form. The serious consequences of fretting sliding compound friction can be greatly reduced by studying the sliding compound friction and wear and taking appropriate measures. Therefore, the research on the implementation of the fretting sliding composite friction and wear test has an important guiding role in correctly evaluating the influence of various friction forms on the friction and wear properties of materials. The friction and wear testing machine can simulate the actual working conditions more realistically, which is of great significance for exploring and verifying the friction and wear mechanism and its influencing factors in actual construction machinery, so as to take appropriate measures to reduce the friction and wear phenomenon.

Invention content:

The invention fills the gap in the existing research field of fretting sliding compound friction and wear, and provides a fretting sliding compound friction and wear test system, which has the advantages of convenient operation, reliable principle, compact structure, stable load, fretting and sliding amplitude. It has the characteristics of high value accuracy and can better reflect the actual working conditions of fretting sliding composite friction and wear characteristics. The amplitude and frequency are set, which can well simulate the actual motion of many friction pairs in the human body and industrial applications, and solve the problem that the existing friction and wear test system cannot carry out relevant simulation research well.

In order to achieve the above purpose, the present invention discloses a micro-motion sliding compound friction and wear test system, which is characterized in that the system includes a support device, a pressure loading device, a three-dimensional force sensor, a micro-motion and sliding drive device, a precision clamping device, Measuring device, friction pair unit, data acquisition card and computer control system;

The support device includes a lower support part and an upper support part fixed on the top of the lower support part. The lower support part consists of four lower support columns and a lower support platform. The lower support platform is fixedly installed above the four lower support columns. The upper support part It consists of four upper support columns and a top plate fixedly installed above the four upper support columns, and the four upper support columns are fixedly installed on the top surface of the lower support platform;

The pressure loading device includes a hydraulic loading device, a hydraulic loading device bracket, a stepped plate, a loading block, and a guide block. The guide block is a hollow cuboid structure, and the cuboid structure consists of a left side, a right side, a front side, and a rear. The side surface and the lower bottom surface are formed, and one end has an opening. The left side of the cuboid structure is provided with a left flap, the right side of the rectangular structure is provided with a right flap, and the left flap and the left side are provided. The included angle is 90°, the included angle between the right flap and the right side is also 90°, the left flap and the right flap are connected with the guide rail above the top plate through the sliding block, and the top plate is provided with a square hole, the cuboid is The structure is located in the square hole, the loading block is in the shape of an inverted "ji", and the main body of the loading block is located inside the guide block and can slide up and down in the guide block; The plate and the right flap are fixedly connected, the hydraulic loading device bracket is fixedly installed on the left and right flaps through the vertical column, the hydraulic loading device is fixedly installed on the bottom surface of the hydraulic loading device bracket, and the output shaft of the hydraulic loading device is fixed with the stepped plate connect;

The friction pair unit includes a block lower sample and a steel ball upper sample;

The micro-motion and sliding drive device includes an electro-hydraulic exciter and a high-precision electric translation stage. The electro-hydraulic exciter is fixedly connected to the top plate through a large L-shaped plate, and one of the side plates of the large L-shaped plate is connected to the electro-hydraulic plate. The vibration exciter is fixedly connected, the other side plate is fixedly connected to the lower surface of the top plate, and the output shaft of the electro-hydraulic vibration exciter is fixedly connected to the right side of the hollow cuboid structure; the high-precision electric translation stage includes high-precision stepping Motor, reduction box, ball screw, slide plate, slider, support block, the support block is in a U-shaped structure, the support block is located between the four upper support columns, the slide plate and the ball screw are connected to the support The two side walls of the block are connected, the high-precision stepper motor is fixedly connected with the reduction box, the output shaft of the reduction box extends into one of the side walls of the support block and is connected with the ball screw, and the slider is provided with a ball screw a threaded through hole and a chute matched with the lever, and the chute is matched with the slide plate;

The measuring device is composed of a scale grating and a grating reading head, the scale grating is fixed on one side of the support block, the grating reading head is fixedly installed on one side of the slider through a small L-shaped plate, the scale grating and the grating are fixed on one side of the slider. The position of the reading head corresponds;

the three-dimensional force sensor is fixedly mounted on the lower end of the loading block;

The precision clamping device includes an upper sample holder system and a lower sample holder, the upper sample holder system is installed below the three-dimensional force sensor, the lower sample holder is placed on the electric translation stage, and the upper sample holder is placed on the electric translation stage. The sample clamp system is used to fix the upper sample of the steel ball, and the lower sample clamp is used to fix the block lower sample; the upper sample clamp system is composed of an upper sample clamp I and an upper sample clamp II, which are passed through the sink. The head screw is fixedly connected, the lower surface of the upper sample holder I is provided with a spherical groove that matches the sample on the steel ball, and the upper sample holder II is provided with a cambered through hole, and the diameter of the cambered through hole is smaller than the diameter of the steel ball , the cambered through hole is used to cooperate with the sample on the steel ball;

The lower sample holder is a hollow block structure, including a left side plate, a right side plate, a front side plate and a rear side plate. The lower surfaces of the plate and the rear side plate are provided with double-layer stepped grooves with the same structure. Fasten tightly. The vertical height of the block lower sample is greater than the vertical height of the side of the first layer of steps, and there is a 0.5mm gap between the bottom surface of the second layer of steps and the upper surface of the lower sample. The lower sample holder is fixedly mounted on the upper surface of the slider by means of bolts.

Further, the present invention also provides a control method of a fretting sliding composite friction and wear test system, comprising the following steps:

Step 1: Set the loading load of the hydraulic loading device; set the motion amplitude and frequency of the drive shaft of the electro-hydraulic exciter, so as to realize the setting of the fretting amplitude and fretting frequency; set the motion amplitude and speed of the high-precision electric translation stage Make settings to realize the setting of sliding amplitude and frequency;

Step 2: The three-dimensional force sensor collects the normal load applied by the hydraulic loading device in the vertical direction and the friction force of the friction pair in the horizontal direction, and the collected analog signal is converted into a digital signal by the data acquisition card. The computer control system compares the collected normal load with the preset normal load, and adjusts the hydraulic loading device according to the difference between the two to ensure the accuracy of the normal load of the friction pair; at the same time, the computer controls The system stores and displays the friction force between the friction pairs in real time; uses the grating ruler to measure the displacement of the upper and lower samples of the high-precision electric translation stage 7 in real time, and at the same time performs closed-loop feedback adjustment of the displacement amplitude to ensure the accuracy of the sliding displacement amplitude sex;

Step 3: By changing the output load size of the hydraulic loading device, changing the motion amplitude and speed of the high-precision electric translation stage, and changing the motion amplitude and frequency of the electro-hydraulic exciter drive shaft, different loads, different sliding amplitudes and speeds, and different micro-motions can be performed. The fretting sliding composite wear test under the amplitude and frequency; by adding a lubricating groove under the friction pair, adding lubricating medium until the contact interface of the friction pair is submerged, the wear test under lubricating conditions can be carried out.

Step 4: By turning on both the electro-hydraulic vibration exciter and the high-precision electric translation stage, the fretting sliding composite wear test can be carried out; by turning off the electro-hydraulic vibration exciter and only opening the high-precision electric translation stage, a pure sliding wear test can be carried out ; Pure fretting wear tests can be carried out by turning off the high-precision electric translation stage and turning on only the electro-hydraulic vibration exciter.

The fretting sliding composite wear test system and the control method thereof of the present invention have the following beneficial effects:

1. The hydraulic closed-loop control loading device is used for loading, which ensures the stability and uniformity of the load application, and the friction pair is always in full contact during the vibration process.

2. The upper sample fixtures Ⅰ and Ⅱ are designed with arc surface. Even if the height of the sample under the plane or the loading load changes, because the upper sample fixture Ⅱ has a large arc surface with a diameter smaller than that of the steel ball, the upper sample The fixture system has a certain radial width to ensure the uniformity of contact and avoid jumping.

3. The lower sample fixture is a hollow block structure, on the one hand, it is used to increase the contact range between the upper and lower samples, and on the other hand, it is beneficial to directly observe the contact relationship between the friction pairs; the lower sample fixture and the lower sample The contact part adopts a double-layer stepped design. The main purpose is to leave a 0.5mm gap between the bottom surface of the second layer of steps and the upper surface of the lower sample to avoid direct contact between the bottom surface of the second layer of steps and the upper surface of the lower sample. The pressure between the two causes damage to the structural features of the lower sample surface.

4. Coordinate through the computer control system, so as to output the wear performance of the friction pair under various load sizes, friction frequency and vibration displacement amplitudes in real time, with convenient operation, stable load and high vibration displacement amplitude precision. Features.

The test system and its control method realized by the invention have the characteristics of convenient operation, reliable principle, compact structure, stable load, high precision of fretting and sliding amplitude, and can well simulate the actual motion modes of many friction pairs in human body and industrial applications. For the actual situation of fretting and sliding composite superposition, it solves the problem that the current friction and wear testing machine cannot carry out relevant simulation research. At the same time, the test system can set the test load, lubrication conditions, sliding speed and speed of sliding friction, and fretting amplitude and frequency of fretting friction. In addition, friction and wear tests in pure fretting and pure sliding modes can be carried out on this test system.

Description of drawings

Fig. 1 is the front view of the overall structure of the present invention;

2 is a partial cross-sectional view of the overall structure of the present invention;

3 is a side view of the overall structure of the present invention;

4 is a schematic structural diagram of a friction pair and a fixture of the present invention;

5 is a schematic structural diagram of the pressure loading device of the present invention;

6 is a schematic diagram of an electric translation stage of the present invention;

Fig. 7 is the structural representation of the sample holder under the present invention;

Fig. 8 is the structural representation of the lubricating groove of the present invention;

FIG. 9 is a schematic structural diagram of the measuring device of the present invention.

Among them: 1- lower support column, 2- lower support platform, 3- upper support column, 4- scale grating, 5- small L-shaped plate, 6- grating reading head, 7- electric translation stage, 8- block lower test sample, 9- lower sample fixture, 10- upper sample fixture II, 11- countersunk head screw, 12- upper sample fixture Ⅰ, 13- three-dimensional force sensor, 14- loading block, 15- guide block, 16- hydraulic pressure Loading device bracket, 17-hydraulic loading device, 18-step plate, 19-guide rail, 20-large L-shaped plate, 21-electro-hydraulic vibration exciter, 22-sample on steel ball, 7-1: high-precision stepping Motor, 7-2: Gearbox, 7-3: Ball screw, 7-4: Electric translation stage shell, 7-5: Dust cover, 7-6: Slider,

Detailed ways

In order to clearly and completely describe the objectives, technical solutions and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In order to achieve the above purpose, the present invention discloses a fretting sliding compound friction and wear test system, which is characterized in that the system includes a support device, a pressure loading device, a three-dimensional force sensor, a fretting and sliding drive device, a precision clamping device, a measuring device, friction pair unit, data acquisition card and computer control system;

The supporting device includes a lower supporting part and an upper supporting part fixed on the top of the lower supporting part; , the upper support part is composed of four upper support columns 3 and a top plate fixedly installed above the four upper support columns, and the four upper support columns are fixedly installed on the top surface of the lower support platform 2;

The pressure loading device includes a hydraulic loading device 17, a hydraulic loading device bracket 16, a stepped plate 18, a loading block 14, and a guide block 15. The guide block 15 is a hollow cuboid structure, and the cuboid structure consists of a left side and a right side. It is composed of a face, a front side, a rear side and a lower bottom surface, and one end has an opening. The angle between the left side is 90°, and the angle between the right flap and the right side is also 90°. The left flap and the right flap are connected to the guide rail 19 above the top plate through the sliding block, and the top plate is opened. There is a square hole, the cuboid structure is located in the square hole, the loading block 14 has an inverted "ji" shape structure, the main part of the loading block 14 is located inside the guide block 15, and can be guided in the guide block 15. The block 15 slides up and down; the loading block 14 and the guide block 15 are a square hole shaft clearance fit; the gap is within 5um, to ensure that the guide block 15 can freely move downward when under the load of the hydraulic loading device to ensure the smooth progress of loading . At the same time, there is a clearance fit between the guide block 15 and the square hole on the top plate, and the gap is 175um to ensure that when the friction pair is fretting wear, the guide block 15 and the top plate will not interfere, ensuring the installation accuracy.

The stepped plate 18 is fixedly connected with the left flap and the right flap, the hydraulic loading device bracket 16 is fixedly installed on the left flap and the right flap through the vertical column, and the hydraulic loading device 17 is fixedly installed on the bottom surface of the hydraulic loading device bracket 16. The output shaft of the loading device 17 is fixedly connected with the stepped plate 18;

The friction pair unit includes a block lower sample and a steel ball upper sample; the friction pair precision clamping unit is used to realize flexible fixed clamping of the friction pair;

The micro-motion and sliding drive device includes an electro-hydraulic exciter 21 and a high-precision electric translation stage 7. The electro-hydraulic exciter 21 is fixedly connected to the top plate through a large L-shaped plate 20, and one of the large L-shaped plates 20 is connected. The side plate is fixedly connected to the electro-hydraulic exciter 21, the other side plate is fixedly connected to the lower surface of the top plate, and the output shaft of the electro-hydraulic exciter 21 is fixedly connected to the right side of the hollow cuboid structure; The translation stage 7 includes a high-precision stepping motor 7-1, a reduction box 7-2, a ball screw 7-3, a slide plate 7-5, a slider, and a support block 7-4. The support block has a U-shaped structure, so The support block is located between the four upper support columns, the slide plate and the ball screw 7-3 are connected to the two side walls of the support block, the high-precision stepper motor 7-1 and the reduction box 7-2 are fixedly connected, The output shaft of the reduction box 7-2 extends into one of the side walls of the support block and is connected with the ball screw 7-3, and the slider is provided with a threaded through hole and a chute matched with the ball screw, so The chute is matched with the sliding plate; the driving force generated by the electro-hydraulic exciter 21 controls the friction pair to generate fretting friction; the driving force generated by the high-precision electric translation stage 7 controls the friction pair to generate sliding friction.

The high-frequency electro-hydraulic exciter 21 is mainly composed of a high-frequency exciter valve, a parallel digital valve, a hydraulic cylinder, a load sensor, a displacement sensor and a built-in high-performance microprocessor. The high-frequency excitation valve is mainly used to generate a high-frequency sinusoidal excitation signal with adjustable amplitude and frequency, and the parallel digital valve is used to process the signal. The computer measurement and control system controls the fretting amplitude and frequency of the friction pair by changing the frequency and amplitude of the sinusoidal excitation signal sent by the high-frequency excitation valve; after the sinusoidal excitation signal is processed by the parallel digital valve, the hydraulic actuator drives the electro-hydraulic vibration exciter 21 The drive shaft performs high-frequency reciprocating motion, which in turn drives the friction pair to produce fretting friction and wear. Among them, the hydraulic actuator can establish a mathematical model to adjust the movement of the drive shaft of the electro-hydraulic exciter 21 through the following formula:

Among them, p1 and p2 are the pressures at both ends of the hydraulic actuator, _{vp is the displacement of the drive shaft of the electro-hydraulic exciter 21, A p is} the cross-sectional area of the drive shaft, m is the load mass, B _c is the viscous resistance constant, and k is the load Rigidity, F _L is the load force.

The upper sample fixtures I12 and II 10 cooperate with the steel ball upper sample 22 to ensure the tightening of the steel ball upper sample 22 in the fixture and prevent the steel ball upper sample 22 from rotating during the friction test. The measuring device is composed of a scale grating 4 and a grating reading head 6, the scale grating 4 is fixed on one side of the support block 7-4, and the grating reading head 6 is fixedly installed on the slider 7 through a small L-shaped plate 5. On one side of the -6, the scale grating 4 corresponds to the position of the grating reading head 6; when the linear slider moves, it can be measured by the displacement change of the grating reading head 6.

The three-dimensional force sensor 13 is fixedly installed on the lower end of the loading block;

The precision clamping device includes an upper sample holder system and a lower sample holder 9, the upper sample holder system is installed below the three-dimensional force sensor 13, and the lower sample holder 9 is placed on the electric translation stage 7, The upper sample holder system is used to fix the upper sample 22 of the steel ball, and the lower sample holder 9 is used to fix the block lower sample 8; the upper sample holder system consists of the upper sample holder 112 and the upper sample holder. II10, the two are fixedly connected by a countersunk head screw 11, the lower surface of the upper sample holder I12 is provided with a spherical groove that matches the sample on the steel ball, and the upper sample holder II10 is provided with an arc surface through hole, and the arc surface is provided with an arc surface. The diameter of the through hole is smaller than the diameter of the steel ball, and the cambered through hole is used to match the sample on the steel ball;

The lower sample holder 9 is a hollow block structure, including a left side plate, a right side plate, a front side plate and a rear side plate. The lower surfaces of the side plate and the rear side plate are provided with double-layer stepped grooves with the same structure, the block-shaped lower sample 8 is fixedly installed in the first-level stepped groove, and the height of the block-shaped lower sample is higher than that of the first step. The depth of the step groove, the lower sample holder 9 is fixed on the upper surface of the slider by bolts. This design has the following advantages. First, the height difference between the lower step and the last step is used to reduce the contact area between the lower sample holder 9 and the block lower sample 8, and reduce the damage to the surface of the lower sample due to the contact pressure; Secondly, after the friction and wear test of a certain contact position of the block lower sample 8 is completed, by moving the lower sample horizontally and changing the contact position of the friction pair again, the multi-position test of the lower sample can be carried out and the test cost can be reduced; finally, After the lower sample has been tested several times in the horizontal direction, when there is no new position for the experiment, the surface of the lower sample can be milled to remove a layer of material, and the test can be restarted on the new surface. The sample holder 9 still firmly fixes the sample, which is beneficial to the recycling of the sample. The lower sample holder 9 and the block lower sample 8 should have good surface parallelism.

The computer control system controls the high-precision stepper motor to send out pulse signals of different numbers and frequencies, and then controls the frequency and speed of the high-precision stepper motor and other parameters. The output torque of the high-precision stepper motor is transmitted to the ball screw through the reduction box, and finally converted into a fixed-length linear motion of the slider, which in turn drives the friction pair to cause sliding friction and wear.

The data acquisition card collects the three-dimensional force sensor signal and the displacement signal of the high-precision electric translation stage 7 and transmits it to the computer control system for closed-loop adjustment, so that the sliding amplitude and speed of the sliding friction and the fretting amplitude and frequency of the fretting friction can be changed in real time. , to carry out the test of the friction pair wear performance under different working conditions; the test system also uses the computer measurement and control system to display, analyze and store data, so as to provide a data basis for the research on the fretting sliding composite damage mechanism of materials.

Further, the present invention also provides a control method of a fretting sliding composite friction and wear test system, comprising the following steps:

Step 1: set the loading load of the hydraulic loading device 17; set the motion amplitude and frequency of the drive shaft of the electro-hydraulic exciter 21, so as to realize the setting of the fretting amplitude and fretting frequency; move the high-precision electric translation stage 7 Set the amplitude and speed, so as to realize the setting of the sliding amplitude and frequency;

Step 2: The three-dimensional force sensor 13 collects the normal load applied by the hydraulic loading device 17 in the vertical direction and the friction force of the friction pair in the horizontal direction, and the data acquisition card converts the collected analog signals into digital signals. The computer control system compares the collected normal load with the set normal load, and adjusts the hydraulic loading device 17 by feedback according to the difference between the two to ensure the accuracy of the normal load of the friction pair; at the same time, the computer controls The system stores and displays the friction force between the friction pairs in real time; uses the grating ruler to measure the displacement of the upper and lower samples of the high-precision electric translation stage 7 in real time, and at the same time performs closed-loop feedback adjustment of the displacement amplitude to ensure the accuracy of the sliding displacement amplitude sex;

Step 3: By changing the magnitude of the output load of the hydraulic loading device 17, changing the movement amplitude and speed of the high-precision electric translation stage 7, and changing the movement amplitude and frequency of the drive shaft of the electro-hydraulic exciter 21, different loads, different sliding amplitudes and speeds, The fretting sliding composite wear test under different fretting amplitudes and frequencies; the wear test under lubricated conditions can be carried out by adding a lubricating groove under the friction pair and adding lubricating medium until the contact interface of the friction pair is submerged.

Step 4: By turning on both the electro-hydraulic vibration exciter 21 and the high-precision electric translation stage 7, the fretting sliding composite wear test can be carried out; by turning off the electro-hydraulic vibration exciter 21 and only opening the high-precision electric translation stage 7, the Pure sliding wear test; pure fretting wear test can be carried out by closing the high-precision electric translation stage 7 and only opening the electro-hydraulic exciter 21 .

LabView software is installed on the computer control system, and the human-computer interaction is realized by inputting the start and stop, signal acquisition and other commands of the electro-hydraulic exciter 21 and the high-precision stepper motor on the software control panel. and speed, fretting amplitude and frequency of fretting friction.

The data acquisition card can collect the signal of the grating scale on the high-precision electric translation stage 7 and the force in the three directions of the three-dimensional force sensor 13x, y, and z. The measured z-direction force is the normal load of the friction pair, and the measured force along the friction The x-direction force of the pair of motion is the friction force of the friction pair. The data acquisition card feeds back the acquired grating ruler signal and three-dimensional force sensor signal to the computer control system. The computer control system can display information such as the sliding amplitude and speed of the current sliding friction, the fretting amplitude and frequency of the fretting friction, and the magnitude of the friction force.

In addition, the friction and wear test in pure fretting and pure sliding modes can be carried out on this test system. The specific method is as follows: the relationship between the vibration amplitude X of the friction pair and the fretting wear\sliding wear is, when X is in the range of 300 microns, That is, the fretting wear experiment can be carried out. At this time, the electric translation stage 7 is turned off, and only the electro-hydraulic vibration exciter 21 is turned on. On the LabView software control panel, the fretting amplitude of the fretting friction is set within 300 microns; , that is, the sliding wear experiment can be carried out. At this time, the electro-hydraulic exciter 21 is turned off, only the electric translation stage 7 is turned on, and the sliding amplitude of the sliding friction is set on the control panel to be above 300 microns.

The test technical indicators that can be realized by this test system are as follows:

1. Normal load: According to the specific friction pair material and working conditions, input different loading loads on the control panel, of which the maximum input load can reach 200N;

2. The sliding range and speed of sliding friction: the sliding range is within 20mm, and the speed is below 10mm/s;

3. The fretting amplitude and frequency of fretting friction: the fretting amplitude is within 300um, and the frequency is below 10Hz;

4. With or without lubrication conditions, as well as fretting sliding composite friction and wear tests under various media.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those of ordinary skill in the art, various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principle and spirit of the present invention, and these modifications, equivalent substitutions and improvements, etc. all fall into the present invention The claimed scope of the present invention is defined by the appended claims and their equivalents.

Claims (8)

1. a fretting sliding composite friction and wear test system, is characterized in that, this system comprises support device, pressure loading device, three-dimensional force sensor, fretting and sliding drive device, precision clamping device, measuring device, friction pair unit, A data acquisition card and a computer control system; the support device includes a lower support part and an upper support part fixed on the top of the lower support part, the lower support part is composed of four lower support columns and a lower support platform, and the lower support platform is fixedly installed on the four Above each lower support column, the upper support part consists of four upper support columns and a top plate fixedly installed above the four upper support columns, and the four upper support columns are fixedly installed on the top surface of the lower support platform; The pressure loading device includes a hydraulic loading device, a hydraulic loading device bracket, a stepped plate, a loading block, and a guide block. The guide block is a hollow cuboid structure, and the cuboid structure consists of a left side, a right side, a front side, and a rear. The side surface and the lower bottom surface are formed, and one end has an opening. The left side of the cuboid structure is provided with a left flap, the right side of the rectangular structure is provided with a right flap, and the left flap and the left side are provided. The included angle is 90°, the included angle between the right flap and the right side is also 90°, the left flap and the right flap are connected with the guide rail above the top plate through the sliding block, and the top plate is provided with a square hole, the cuboid is The structure is located in the square hole, the loading block is in the shape of an inverted "ji", and the main body of the loading block is located inside the guide block and can slide up and down in the guide block; The plate and the right flap are fixedly connected, the hydraulic loading device bracket is fixedly installed on the left and right flaps through the vertical column, the hydraulic loading device is fixedly installed on the bottom surface of the hydraulic loading device bracket, and the output shaft of the hydraulic loading device is fixed with the stepped plate connect; The friction pair unit includes a block lower sample and a steel ball upper sample. 2. A kind of fretting sliding compound friction and wear test system as claimed in claim 1, is characterized in that, described precision clamping device comprises upper sample holder system and lower sample holder, and described upper sample holder system is installed Below the three-dimensional force sensor, the lower sample holder is placed on the electric translation stage, the upper sample holder system is used to fix the upper sample of the steel ball, and the lower sample holder is used to fix the block lower sample ;The upper sample fixture system consists of the upper sample fixture Ⅰ and the upper sample fixture Ⅱ, which are fixedly connected by countersunk screws, and the lower surface of the upper sample fixture Ⅰ is provided with a spherical groove that matches the sample on the steel ball , The upper sample holder II is provided with a cambered through hole, the diameter of the cambered through hole is smaller than the diameter of the steel ball, and the cambered through hole is used to match the sample on the steel ball. 3. A kind of fretting sliding compound friction and wear test system as claimed in claim 2, it is characterized in that, the lower sample holder is a hollow block structure, comprising left side plate, right side plate, front side plate and rear side plate The upper surfaces of the front side plate and the rear side plate are provided with two threaded through holes, and the lower surfaces of the front side plate and the rear side plate are provided with double-layer stepped grooves with the same structure. The side is fixed left and right by the side of the first layer of the ladder, the upper surface of the lower sample is pressed and fixed by the bottom surface of the first layer of the ladder, the vertical height of the block-shaped lower sample is greater than the vertical height of the side of the first layer of the ladder, and the lower sample fixture is bolted It is fixedly installed on the upper surface of the slider. 4. a kind of fretting sliding compound friction and wear test system as claimed in claim 3 is characterized in that, described fretting and sliding drive device comprises electro-hydraulic vibration exciter and high-precision electric translation stage, described electro-hydraulic exciter The vibrator is fixedly connected to the top plate through the large L-shaped plate, one of the side plates of the large L-shaped plate is fixedly connected to the electro-hydraulic exciter, the other side plate is fixedly connected to the lower surface of the top plate, and the output shaft of the electro-hydraulic exciter is fixedly connected to the top plate. The right side of the hollow cuboid structure is fixedly connected; the high-precision electric translation stage includes a high-precision stepper motor, a reduction box, a ball screw, a slide plate, a slider, and a support block, and the support block is in a U-shaped structure. The support block is located between the four upper support columns, the slide plate and the ball screw are connected to the two side walls of the support block, the high-precision stepper motor and the reduction box are fixedly connected, and the output shaft of the reduction box extends into the One of the side walls of the support block is connected with the ball screw, the sliding block is provided with a threaded through hole and a chute matched with the ball screw, and the chute is matched with the slide plate. 5. A kind of fretting sliding compound friction and wear test system as claimed in claim 4, is characterized in that, described measuring device is made up of scale grating and grating reading head, scale grating is fixed on a side surface of described support block, The grating reading head is fixedly mounted on one side of the slider through a small L-shaped plate, and the position of the scale grating and the grating reading head corresponds to each other. 6 . The fretting sliding compound friction and wear test system according to claim 1 , wherein the three-dimensional force sensor is fixedly installed on the lower end of the loading block. 7 . 7. A fretting sliding compound friction and wear test system according to claim 1, characterized in that, the loading block and the guide block are a square hole shaft clearance fit; the guide block and the square hole opened on the top plate For clearance fit, the clearance is 175um. 8. a control method of a fretting sliding compound friction and wear test system, the method adopts a kind of fretting sliding compound friction and wear test system as described in any one of claims 1-7, is characterized in that, comprises the steps: Step 1: Set the loading load of the hydraulic loading device; set the motion amplitude and frequency of the drive shaft of the electro-hydraulic exciter, so as to realize the setting of the fretting amplitude and fretting frequency; set the motion amplitude and speed of the high-precision electric translation stage Make settings to realize the setting of sliding amplitude and frequency; Step 2: The three-dimensional force sensor collects the normal load applied by the hydraulic loading device in the vertical direction and the friction force of the friction pair in the horizontal direction, and the data acquisition card converts the collected analog signals into digital signals, and the computer control system The collected normal load is compared with the preset normal load, and the hydraulic loading device is feedback adjusted according to the difference between the two to ensure the accuracy of the normal load of the friction pair; The friction force between pairs is stored and displayed in real time; the grating ruler is used to measure the displacement of the upper and lower samples of the high-precision electric translation stage in real time, and the closed-loop feedback adjustment of the displacement amplitude is carried out to ensure the accuracy of the sliding displacement amplitude; Step 3: By changing the output load size of the hydraulic loading device, changing the motion amplitude and speed of the high-precision electric translation stage, and changing the motion amplitude and frequency of the electro-hydraulic exciter drive shaft, different loads, different sliding amplitudes and speeds, and different micro-motions can be performed. The fretting sliding composite wear test under the amplitude and frequency; by adding a lubricating groove under the friction pair, adding lubricating medium until the contact interface of the friction pair is submerged, the wear test under lubricating conditions can be carried out; Step 4: By turning on both the electro-hydraulic vibration exciter and the high-precision electric translation stage, the fretting sliding composite wear test can be carried out; by turning off the electro-hydraulic vibration exciter and only opening the high-precision electric translation stage, a pure sliding wear test can be carried out ; Pure fretting wear tests can be carried out by turning off the high-precision electric translation stage and turning on only the electro-hydraulic vibration exciter.

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