Test apparatus useful for friction coefficient measurements and lubrication curve plotting

Abstract

The utility model discloses a kind of test device that can be used for friction coefficient measurement and lubrication curve drawing, it is related to testing and detection technical field, solve the problem of complex structure of friction test device in prior art.The utility model includes host computer and the signal acquisition and control system connected with host computer, further include motor, motor is installed on shell, shell is fixed on bearing platform, shell is also equipped with the test assembly of detachable connection with motor in it.Motor and test assembly are detachably connected, the type of test assembly is replaced easily, and the scope of application is wide.Motor and test assembly are all arranged in shell, can protect motor and test assembly, also avoid the influence of external factor on test to some extent.The device can simulate the motion characteristic and friction characteristic in rotating mechanism, and can accurately measure friction coefficient and draw lubrication curve according to different lubrication state.

Description

Technical Field

[0001] This utility model relates to the field of testing and detection technology, and in particular to a testing device that can be used for measuring the coefficient of friction and plotting lubrication curves. Background Technology

[0002] In the field of tribology, measuring the coefficient of friction and plotting lubrication curves are key technologies for evaluating the lubrication performance of materials. Various methods and technologies have been developed both domestically and internationally to achieve these goals. Commonly used methods for measuring the coefficient of friction include the inclined plane method and the Amonton method, and commonly used testing equipment includes dynamic friction testers and reciprocating friction testers. The inclined plane method is a traditional method for measuring the coefficient of friction. By adjusting the angle of the inclined plane until the object begins to slide, the tangent of the friction angle is calculated to obtain the coefficient of friction. The Amonton method is based on the principle that frictional force is proportional to normal force, and determines the coefficient of friction by measuring the frictional force under different normal forces. Dynamic friction testers are used to measure the coefficient of friction of materials under dynamic conditions. They include a moving platform that can be moved at different speeds, measuring the traction force as the object moves on the platform. Reciprocating friction testers simulate the reciprocating motion of many components in actual use, measuring the change of frictional force over time and the number of reciprocating motions, and evaluating wear and the stability of the coefficient of friction during the friction process.

[0003] The plotting of lubrication curves (also known as Stribeck curves) is an important tool for describing the relationship between lubrication state and coefficient of friction, and is often accomplished using a disc friction testing device. This device obtains lubrication curves involving thin-film lubrication by changing the rotational speed of the disc, identifying thin-film lubrication regions, and is commonly used to analyze the influence of surface roughness on lubrication state. In China, researchers have studied the lubrication state of friction pairs with different surface roughnesses, finding that friction pairs with smaller surface roughness are more prone to forming thin-film lubrication, while the thin-film lubrication state is not obvious for friction pairs with larger surface roughness. International researchers are also exploring new methods for friction coefficient detection and lubrication curve plotting, such as using a friction and wear testing machine (UMT) to test the friction and wear of materials, and studying the influence of different lubricating materials on wheel-rail wear and rolling contact fatigue. Utility Model Content

[0004] To address the shortcomings in the aforementioned background technology, this utility model proposes a testing device that can be used for measuring the coefficient of friction and plotting lubrication curves, thus solving the problem of complex structures in existing friction testing devices.

[0005] The technical solution of this utility model is as follows: A test device for measuring friction coefficient and plotting lubrication curves includes a host computer and a signal acquisition and control system connected to the host computer, and also includes a motor, which is mounted on a housing, the housing is fixed on a support platform, and a test component detachably connected to the motor is provided inside the housing.

[0006] More preferably, the test assembly includes a test shaft, the upper part of which is connected to a coupling. The test shaft is connected to the output shaft of the motor via the coupling. A bearing assembly is detachably connected to the test shaft. The bearing assembly is installed inside a metal housing, and the metal housing has a lubrication cavity that mates with the bearing assembly.

[0007] More preferably, the bearing assembly is a sliding bearing, which is detachably connected to the experimental shaft and detachably mounted on a positioning component inside the metal housing.

[0008] More preferably, the bearing assembly includes a bearing base installed in a metal housing, and the bearing base is provided with a bushing or bearing shell that mates with the experimental shaft.

[0009] More preferably, a pressure sensor is provided on the inner wall of the metal shell, and the pressure sensor is electrically connected to the signal acquisition and control system through an amplifier.

[0010] In a further preferred embodiment, the metal casing is also provided with a hydraulic pump and a pressure control mechanism that cooperate with the bearing assembly. The hydraulic pump and the pressure control mechanism are connected to the signal acquisition and control system via a frequency converter.

[0011] More preferably, a torque sensor is provided on the output shaft of the motor, the torque sensor is located between the coupling and the motor, and the torque sensor is electrically connected to the signal acquisition and control system.

[0012] More preferably, a speed sensor is also connected to the upper part of the motor, and the speed sensor is electrically connected to the signal acquisition and control system.

[0013] More preferably, the motor is connected to a second frequency converter, and the motor is electrically connected to the signal acquisition and control system through the second frequency converter.

[0014] More preferably, the housing is provided with a mounting frame, which is fixed on the support platform, and both the motor and the metal housing are mounted on the mounting frame.

[0015] The beneficial effects of this invention are as follows: The motor and testing components are detachably connected, facilitating the replacement of different types of testing components and broadening its applicability. Both the motor and testing components are housed within a casing, protecting them and mitigating the influence of external factors on the testing process. This device can simulate the motion and friction characteristics of rotating mechanisms and accurately measure the coefficient of friction and plot lubrication curves based on different lubrication conditions. This not only overcomes the shortcomings of existing technologies but also provides crucial data and technical support for the design and development of new materials, the safe testing of new samples, and the digital twinning of new equipment. Attached Figure Description

[0016] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model;

[0018] Figure 2 This is a graph showing the bearing friction coefficient and lubrication curve of this utility model.

[0019] In the diagram: 1. Host computer, 2. Support platform, 3. Signal acquisition and control system, 4. Amplifier, 5. Frequency converter one, 6. Hydraulic pump and pressure control mechanism, 7. Frequency converter two, 8. Housing, 9. Speed ​​sensor, 10. Motor, 11. Torque sensor, 12. Coupling, 13. Experimental shaft, 14. Lubrication chamber, 15. Bearing bush, 16. Bearing base, 17. Pressure sensor. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] like Figure 1 and Figure 2 As shown in Embodiment 1, a testing device for measuring friction coefficient and plotting lubrication curves includes a host computer 1 and a signal acquisition and control system 3 connected to the host computer 1. It also includes a motor 10, which is mounted on a housing 8. The housing 8 is fixed to a support platform 2. Inside the housing 8, a test component detachably connected to the motor 10 is also provided. The host computer 1 is a control and display terminal, where the curve plot is viewed. Specifically, the host computer 1 is a computer. The signal acquisition and control system 3 uses a National Instruments DAQ series, Compact RIO series, or PXI series data acquisition card. The host computer program uses LabVIEW-based signal acquisition and control software. The detachable connection between the motor 10 and the test component facilitates replacement of the test component type and has a wide range of applications. Both the motor 10 and the test component are housed within the housing 8, protecting them and also mitigating the influence of external factors on the test.

[0022] In this embodiment, the testing assembly includes an experimental shaft 13, with a coupling 12 connected to its upper part. The experimental shaft is connected to the output shaft of the motor 10 via the coupling 12. A bearing assembly is detachably connected to the experimental shaft 13, and the bearing assembly is installed inside a metal shell. The metal shell contains a lubrication cavity 14 that mates with the bearing assembly. The lubrication cavity 14 contains lubricating oil, which lubricates the bearing, thereby enabling the plotting of the lubrication curve. The metal shell is preferably a rectangular structure, fixed on a support platform 2, which serves as the experimental table. The outer shell 8 is a transparent acrylic glass box for easy observation of the experimental equipment, and is fixed to the experimental table with screws.

[0023] In this embodiment, the bearing assembly is a sliding bearing, which is detachably connected to the experimental shaft 13. The sliding bearing is detachably mounted on a positioning element inside the metal housing. The bearing assembly includes a bearing base 16 mounted inside the metal housing, and a bushing or bearing shell 15 that mates with the experimental shaft 13 is provided inside the bearing base 16. The bearing base 16 is positioned inside the metal housing by a positioning element. The positioning element can be a limiting ring integral with the metal housing, or an existing clamp that serves a limiting function can be used. The positioning element is a commonly used component for fixing the bearing base and can be purchased directly without being described in detail here. The bushing or bearing shell 15 is detachably connected to the experimental shaft 13, facilitating the replacement of the experimental shaft 13 and the corresponding bearing shell 15 that mates with the experimental shaft 13.

[0024] like Figure 2As shown in Embodiment 2, a testing device for measuring friction coefficient and plotting lubrication curves is provided. A pressure sensor 17 is mounted on the inner wall of the metal casing. The pressure sensor 17 is electrically connected to a signal acquisition and control system 3 via an amplifier 4. The pressure sensor 17, installed between the programmable load system and the detachable sliding bearing system, is used to detect the real-time load during mechanical operation. The signal acquisition and control system 3 is mounted on a test bench and connected to the amplifier 4 via wires. The amplifier 4 is connected to the pressure sensor 17 via wires. The pressure sensors 17 are symmetrically arranged on the inner wall of the metal casing to measure the load, i.e., the normal force on the bearing. The metal casing also includes a hydraulic pump and a pressure control mechanism 6 that cooperate with the bearing assembly. The hydraulic pump and pressure control mechanism are connected to the signal acquisition and control system 3 via a frequency converter 7. The hydraulic pump and pressure control mechanism 6 consist of a conventional hydraulic pump, hydraulic sensor, and CNC valve; this part mainly provides dynamic load for the system. The hydraulic pump is normally open. After the required dynamic load is set on the host computer 1, it is transmitted to the CNC valve in this part via the signal acquisition and control system 3. The CNC valve opens dynamically under the action of the signal, and the real-time hydraulic pressure is fed back to the signal acquisition and control system 3 via the hydraulic sensor to achieve negative feedback. The hydraulic pump and pressure control mechanism 6 are connected to the metal shell through the outer shell 8 via hydraulic pipelines to apply pressure to the bearing assembly inside the metal shell. The hydraulic pump and pressure control mechanism are electrically connected to the frequency converter 7 via wires. The frequency converter 7 is electrically connected to the signal acquisition and control system 3 via wires. The host computer 1 controls the hydraulic pump and pressure sensor 17 connected to the signal acquisition and control system 3. The signal acquisition and control system 3 controls the hydraulic pump and pressure control mechanism 6 to apply pressure to the metal shell to simulate the load load through the frequency converter 7. The hydraulic pump and pressure sensor 17 provide external load for the experimental rotating shaft 13 and sliding bearing in operation, and are in direct contact with the sliding bearing base 16. The load control device realizes the application of constant or variable load to the bearing system.

[0025] In this embodiment, a torque sensor 11 is provided on the output shaft of the motor 10. The torque sensor 11 is located between the coupling 12 and the motor 10, and is electrically connected to the signal acquisition and control system 3. The torque sensor 11, installed between the motor 10 and the experimental bearing, is used to detect the real-time torque during the operation of the mechanical device. A speed sensor 9 is also connected to the upper part of the motor 10, and is electrically connected to the signal acquisition and control system 3. The speed sensor 9, mounted on the motor 10, is used to detect the real-time speed of the mechanical device. A frequency converter 7 is connected to the motor 10, and the motor 10 is electrically connected to the signal acquisition and control system 3 through the frequency converter 7. The motor 10 provides kinetic energy input, and the frequency converter 7 controls the rotary motor 10. The rotary motor 10 is connected to the experimental shaft 13, realizing the uniform or variable speed rotation of the experimental shaft 13.

[0026] In this embodiment, the housing 8 is equipped with a mounting frame, which is a rectangular frame fixed to the support platform 2. Both the motor 10 and the metal housing are mounted on the mounting frame. The mounting frame is fixed to the test bench with screws, serving as a support structure for the motor 10 and the metal housing, and fixing the motor 10 to prevent it from tipping over during use, thus affecting the experimental results and consequently the curve plotting.

[0027] In the specific plotting of bearing friction coefficient and lubrication curve, the frictional torque of the bearing system is balanced with the power torque of motor 10. The frictional torque can be calculated based on the bearing inner diameter, using the following formula: ,in Let N be the coefficient of friction, N be the bearing load, and r be the nominal radius of the bearing. The type of bearing, the load it bears, the rotational speed, and the lubrication method all have a significant impact on the coefficient of friction. Figure 2 The vertical axis represents the coefficient of friction of the contact surface between the experimental shaft 13, the lubricant, and the sliding bearing. The horizontal axis represents the lubrication coefficient. , ,in The viscosity coefficient of the lubricant. Let r be the angular velocity of the experimental shaft 13, r be the shaft radius, and W be the load. Under constant load and constant speed conditions, the signal output from the parameter measurement module is input to the computer. The processing software will calculate the friction coefficient under the current material combination conditions based on the measured torque and pressure data, combined with the dimensional parameters of the experimental shaft 13 and the bearing. Under constant load variable speed test and constant speed variable load test conditions, the processing software will plot the lubrication curve under the current material combination conditions based on the calculated friction coefficient, the measured speed and pressure data, and the viscosity parameters of the lubricant, and analyze the lubrication state under variable speed or variable load conditions.

[0028] All other structures are the same as in Example 1.

[0029] like Figure 1 and Figure 2As shown in Example 3, a testing device for measuring friction coefficient and plotting lubrication curves includes a metal shell containing a cavity. The cavity houses an experimental shaft, a sliding bearing, and a lubricant reservoir. The sliding bearing is detachable and mounted on the experimental shaft. The experimental shaft is connected to a motor and rotates with it. The other end of the experimental shaft, also fitted with the sliding bearing, is located inside the cavity. The sliding bearing mainly consists of a bearing base, a bearing bush or sleeve, and a positioning element. The bearing bush or sleeve is mounted on the experimental shaft, and the bearing base houses the bearing bush or sleeve. The bearing base has a positioning element, allowing the sliding bearing to be accurately installed in the cavity. A speed sensor is mounted on the motor, and a torque sensor is installed between the motor and the bearing. A hydraulic pump and a pressure control mechanism are connected externally to the cavity. Two pressure sensors are installed inside the cavity between the cavity and the bearing base. The motor input is electrically connected to the output of a frequency converter, and the frequency converter input is electrically connected to the output of a control system. The input terminals of the hydraulic pump and pressure control mechanism are electrically connected to the output terminal of frequency converter two. The input terminal of frequency converter two is electrically connected to the output terminal of the control system, and the input terminal of the control system is electrically connected to the output terminal of the control and display terminal. The output terminals of the speed sensor and torque sensor are electrically connected to the input terminal of the signal acquisition system. The output terminal of the pressure sensor is electrically connected to the input terminal of the amplifier, the output terminal of the amplifier is electrically connected to the input terminal of the signal acquisition system, and the output terminal of the signal acquisition system is electrically connected to the input terminal of the control and display terminal.

[0030] The system consists of a signal acquisition and control system, a frequency converter, and a motor. The control terminal controls the frequency converter via the control system, thereby controlling the motor speed to provide power to the detachable sliding bearing system. The detachable sliding bearing system comprises an experimental shaft, sliding bearings, a cavity, and detachable bearing bushes. The cavity contains lubricating oil to provide real-time lubrication between the experimental shaft and the bearings. The motor is connected to the experimental shaft via a coupling to provide rotational power. The programmable load system consists of a signal acquisition and control system, a frequency converter, a hydraulic pump, and a pressure control mechanism. The signal acquisition and control system controls the hydraulic pump and pressure control mechanism via the frequency converter to apply pressure to the cavity to simulate a load. The parameter measurement module consists of a pressure sensor, a torque sensor, and a speed sensor. The speed sensor measures the motor speed to obtain the angular velocity of the experimental shaft. The pressure sensor, connected to the inner wall of the cavity and the sliding bearing, can measure the load (normal force on the bearing) N. The torque sensor, installed between the motor and the coupling, can measure the torque M of the experimental shaft rotating under different loads. The data measured by the parameter measurement module is transmitted in real time to the signal acquisition and control system, and then output to the computer control terminal. The computer control terminal, through the software testing module, combines the measured torque and pressure data with the dimensional parameters of the experimental shaft and bearing using formulas. The coefficient of friction is calculated, where r is the radius of the experimental shaft. The computer terminal then uses the calculated coefficient of friction, real-time measured rotational speed and pressure data, and the viscosity parameters of the lubricant to plot a lubrication curve, where the vertical axis of the lubrication curve represents the coefficient of friction. The horizontal axis represents the lubrication coefficient. : . like Figure 2 As shown, where This refers to the viscosity coefficient of the lubricant. Lubrication curves can be used to identify three different lubrication states between the shaft, lubricant, and sliding bearing: boundary lubrication, mixed lubrication, and hydrodynamic lubrication. This allows for adjustments to the load, speed, and lubricating oil to optimize the experiment.

[0031] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A testing device for measuring friction coefficient and plotting lubrication curves, comprising a host computer (1) and a signal acquisition and control system (3) connected to the host computer (1), characterized in that: It also includes a motor (10), which is mounted on a housing (8). The housing (8) is fixed on a support platform (2). The housing (8) also contains a test component that is detachably connected to the motor (10).

2. The testing device for measuring friction coefficient and plotting lubrication curves according to claim 1, characterized in that: The test assembly includes an experimental shaft (13), with a coupling (12) connected to the upper part of the experimental shaft (13). The experimental shaft is connected to the output shaft of the motor (10) through the coupling (12). A bearing assembly is detachably connected to the experimental shaft (13). The bearing assembly is installed in a metal shell, and a lubrication cavity (14) that cooperates with the bearing assembly is provided in the metal shell.

3. The testing apparatus for measuring friction coefficient and plotting lubrication curves according to claim 2, characterized in that: The bearing assembly is a sliding bearing, which is detachably connected to the experimental shaft (13) and is detachably mounted on a positioning component inside the metal shell.

4. The testing apparatus for measuring the coefficient of friction and plotting lubrication curves according to claim 2 or 3, characterized in that: The bearing assembly includes a bearing base (16) installed in a metal shell, and a bushing or bearing shell (15) that mates with the experimental shaft (13) is provided in the bearing base (16).

5. The testing apparatus for measuring friction coefficient and plotting lubrication curves according to claim 4, characterized in that: A pressure sensor (17) is provided on the inner wall of the metal shell. The pressure sensor (17) is electrically connected to the signal acquisition and control system (3) through an amplifier (4).

6. The testing apparatus for measuring friction coefficient and plotting lubrication curves according to claim 5, characterized in that: The metal shell is also equipped with a hydraulic pump and a pressure control mechanism (6) that cooperate with the bearing assembly. The hydraulic pump and pressure control mechanism are connected to the signal acquisition and control system (3) through a frequency converter (5).

7. The testing apparatus for measuring the coefficient of friction and plotting lubrication curves according to claim 5 or 6, characterized in that: A torque sensor (11) is provided on the output shaft of the motor (10). The torque sensor (11) is located between the coupling (12) and the motor (10), and the torque sensor (11) is electrically connected to the signal acquisition and control system (3).

8. The testing apparatus for measuring friction coefficient and plotting lubrication curves according to claim 7, characterized in that: The upper part of the motor (10) is also connected to a speed sensor (9), and the speed sensor (9) is electrically connected to the signal acquisition and control system (3).

9. The testing apparatus for measuring friction coefficient and plotting lubrication curves according to claim 8, characterized in that: The motor (10) is connected to a frequency converter (7), and the motor (10) is electrically connected to the signal acquisition and control system (3) through the frequency converter (7).

10. The testing apparatus for measuring the coefficient of friction and plotting lubrication curves according to claim 8 or 9, characterized in that: The outer shell (8) is provided with an installation frame, which is fixed on the support platform (2). The motor (10) and the metal shell are both installed on the installation frame.

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