Device for testing friction coefficient

Abstract

The utility model provides a device for testing a friction coefficient, which comprises a traction device, a traction wire, a test board, a friction pair, a test sample, a low-temperature liquid container and a temperature measuring component, the test sample is fixed at the bottom of the low-temperature liquid container, the friction pair is fixed on the test board and is arranged below the test sample, and the temperature measuring component is arranged below the test sample. The friction pair is connected with the temperature measuring assembly, the temperature measuring assembly is used for measuring the temperature of the friction interface, and the traction device is connected with the low-temperature liquid container through a traction line. The low-temperature friction coefficient tester is provided with the traction device, the traction wire, the test board, the friction pair, the test sample, the low-temperature liquid container and the temperature measuring assembly, so that the friction coefficient can be tested in a normal-temperature environment, the low-temperature friction coefficient can be measured in a low-temperature environment, the state of the test sample can be observed at any time during testing, and the test efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of friction coefficient testing technology, and more specifically, to a device for testing the friction coefficient. Background Technology

[0002] Friction is one of the fundamental properties of materials. The coefficient of friction is the ratio between the frictional force between two surfaces and the perpendicular force acting on those surfaces. It is usually related to the surface roughness but not to the size of the contact area. Based on the nature of the motion, it can be divided into dynamic friction coefficient and static friction coefficient. The lower the coefficient of friction, the smoother the surface and the smaller the sliding resistance. Currently, there are various methods for testing the coefficient of friction of materials, but for materials used in low-temperature applications, testing the low-temperature friction coefficient remains difficult.

[0003] The prior art disclosed in CN 217033560 U is a friction coefficient tester for thermoplastic elastomer on ice. The tester includes a low-temperature constant temperature chamber and a force measuring instrument. A placement platform is installed inside the low-temperature constant temperature chamber. An ice block is fixedly connected to the placement platform, and a test medium is placed on the top surface of the ice block. A slider is slidably connected to the force measuring instrument. A force sensor is fixedly connected to the slider. A traction wire is connected to the force sensor, and the other end of the traction wire extends through the opening and is fixedly connected to the test medium. A driving component is installed on the force measuring instrument to drive the slider to move closer to or further away from the test medium. A controller electrically connected to the force sensor is provided inside the force measuring instrument. Existing technologies can only test the coefficient of friction at low temperatures on ice surfaces, not at room temperature. Furthermore, the test medium and ice are placed in a low-temperature constant temperature chamber, but the moisture environment in the chamber can cause the test medium and ice to stick together, making it difficult to detect during testing and resulting in low testing efficiency. Utility Model Content

[0004] In view of this, the present invention aims to provide a device for testing the coefficient of friction. This addresses the problems of existing technologies, which can only test the coefficient of friction at low temperatures on ice surfaces, but not at room temperature. Furthermore, the existing technology requires the test medium and ice to be placed in a low-temperature constant temperature chamber, where the moisture environment can cause the test medium and ice to adhere, making it difficult to detect during testing and resulting in low testing efficiency.

[0005] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0006] An apparatus for testing the coefficient of friction includes a traction device, a traction line, a test platform, a friction pair, a test sample, a cryogenic liquid container, and a temperature measuring component. The test sample is fixed to the bottom of the cryogenic liquid container, the friction pair is fixed to the test platform, the friction pair is positioned below the test sample, the friction pair is connected to the temperature measuring component, the temperature measuring component is used to measure the temperature at the friction interface, and the traction device is connected to the cryogenic liquid container via the traction line.

[0007] By setting up a traction device, traction line, test bench, friction pair, test sample, cryogenic liquid container, and temperature measuring component, it is possible to test the coefficient of friction in a normal temperature environment, as well as to determine the coefficient of friction in a low temperature environment. Moreover, the state of the test sample can be observed at any time during the test, thus improving the testing efficiency.

[0008] Furthermore, the temperature measuring component includes a thermocouple and a temperature measuring device, wherein the thermocouple is connected to the temperature measuring device and the thermocouple is connected to the friction pair.

[0009] Furthermore, multiple thermocouples can be provided.

[0010] Furthermore, two thermocouples are provided, each positioned on a side of the friction pair. This arrangement improves the accuracy of the test.

[0011] Furthermore, both the traction device and the cryogenic liquid container are equipped with pull rings, which are connected to the traction line.

[0012] Furthermore, the cryogenic liquid container is equipped with an insulation layer. This feature reduces liquid evaporation and improves the accuracy of the test.

[0013] Furthermore, the friction pair is one of steel plate or aluminum alloy plate.

[0014] Furthermore, the traction device is a horizontal mechanical testing machine.

[0015] Furthermore, the temperature measuring device is a thermometer with a temperature measuring range of -200℃ to 200℃.

[0016] Furthermore, the thermocouple used is a type K thermocouple with a temperature measurement range of -200℃ to 200℃.

[0017] Compared with existing technologies, the device for testing the coefficient of friction described in this utility model has the following advantages:

[0018] 1) This utility model is equipped with a traction device, traction line, test platform, friction pair, test sample, low temperature liquid container, and temperature measuring component. It can not only test the coefficient of friction in a normal temperature environment, but also complete the determination of the coefficient of friction in a low temperature environment. Moreover, the state of the test sample can be observed at any time during the test, thus improving the testing efficiency.

[0019] 2) The equipment of this utility model is simple, easy to operate, and low in cost, and has great application value for engineering design or evaluation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a device for testing the coefficient of friction according to the present invention. Figure 1 ;

[0021] Figure 2 This is a schematic diagram of a device for testing the coefficient of friction according to the present invention. Figure 2 .

[0022] Explanation of reference numerals in the attached figures:

[0023] 1-Traction device, 2-Traction line, 3-Test stand, 4-Friction pair, 5-Test sample, 6-Cryogenic liquid container, 7-Thermocouple, 8-Temperature measuring device. Detailed Implementation

[0024] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. In addition, a brief explanation of the directions involved in the following specific embodiments is provided: the directions or positional relationships indicated by "up," "down," "left," "right," etc., mentioned in the embodiments refer to the directions or positional relationships shown in the accompanying drawings.

[0025] like Figures 1-2 As shown, this utility model relates to a device for testing the coefficient of friction, including a traction device 1, a traction line 2, a test platform 3, a friction pair 4, a test sample 5, a cryogenic liquid container 6, and a temperature measuring component. The test sample 5 is fixed to the bottom of the cryogenic liquid container 6, the friction pair 4 is fixed on the test platform 3, the friction pair 4 is disposed below the test sample 5, the friction pair 4 is connected to the temperature measuring component, and the temperature measuring component is used to measure the temperature at the friction interface. The traction device 1 is connected to the cryogenic liquid container 6 through the traction line 2.

[0026] During the low-temperature friction coefficient test, the device fills a cryogenic liquid container with cryogenic liquid. Temperature is conducted through the bottom of the container to the test sample and the friction pair. A temperature measuring component records the temperature of the friction pair surfaces. When the test temperature is reached, a traction device moves the cryogenic liquid container and the test sample fixed to the bottom of the container relative to the friction pair, recording the traction force F and calculating the friction coefficient μ = F / Fn. Here, Fn is the normal force, which can be obtained from the total mass m of the cryogenic liquid container (containing the cryogenic liquid) and the test sample; Fn = mg, and g is the acceleration due to gravity, taken as 9.8 m / s². When F is the maximum traction force Fmax at the start of relative motion, μ is the static friction coefficient; when F is the traction force Fs at a stable sliding speed, μ is the sliding friction coefficient.

[0027] Specifically, the temperature measuring component includes a thermocouple 7 and a temperature measuring device 8, wherein the thermocouple is connected to the temperature measuring device and the thermocouple is connected to the friction pair.

[0028] Specifically, multiple thermocouples may be provided.

[0029] Specifically, two thermocouples are provided, each positioned on one side of the friction pair. Preferably, the thermocouples are positioned at the center of the side of the friction pair.

[0030] Specifically, the thermocouple probe is fixed in the middle of both sides of the friction pair with low-temperature resistant resin, and the temperature probe is completely wrapped in low-temperature resistant resin. The temperature probe is 5-10 mm away from both sides of the test sample.

[0031] Specifically, the cryogenic liquid container 6 has an internal insulation layer.

[0032] More specifically, the cryogenic liquid container 6 includes a main body and a lid. The inner walls of the main body are provided with an insulation layer, and the end of the lid that contacts the main body is also provided with an insulation layer. The bottom of the main body does not have an insulation layer, which facilitates temperature conduction. Preferably, the insulation layer is made of insulating material to slow down heat loss from the cryogenic liquid.

[0033] More specifically, the lid has a hole to facilitate the filling of cryogenic liquid and to observe the liquid level in the cryogenic liquid container. The inner wall of the cryogenic liquid container is engraved with scale lines to record the volume of the liquid in the cryogenic liquid container and then calculate the weight of the liquid in the cryogenic liquid container. A pull rod is installed at one end of the cryogenic liquid container and connected to a traction device through a traction line.

[0034] Specifically, the test sample is fixed to the bottom of the cryogenic liquid container. The fixing method must not damage the test surface of the sample. The fixing method can be adhesive bonding or mechanical fixation. The friction pair is fixed to the test stage. The fixing method must not damage the test surface. The fixing method can be adhesive bonding or mechanical fixation. The width of the friction pair is more than 20mm larger than the width of the sample to facilitate the fixing of the temperature measuring thermocouple in the middle position on both sides of the friction pair.

[0035] Specifically, the traction device is capable of constant displacement, and the traction speed is adjustable. The traction device is equipped with a force sensor that records force and displacement data during testing.

[0036] Specifically, the height of the test platform, the height of the cryogenic liquid container pull ring, the thickness of the test sample, and the thickness of the friction pair are all consistent with the height of the connection position of the traction line on the traction device, ensuring that both ends of the traction line are at the same horizontal height and that the connection positions of both ends of the traction line are on the same axis.

[0037] This utility model also provides a method for testing the coefficient of friction, using the above-described apparatus, comprising the following steps:

[0038] (1) Fix the test sample on the bottom of the cryogenic liquid container and weigh the mass m1 of the cryogenic liquid container and the sample using a balance;

[0039] (2) Fix the friction pair on the test platform, and use low-temperature resistant adhesive to fix the probes of the two thermocouples in the middle position on both sides of the friction pair. The temperature probe is about 5mm away from the edge of the sample. Connect the thermocouples to the temperature measuring device.

[0040] (3) Place the cryogenic liquid container with the sample on the friction pair, adjust the position of the sample to be centered, connect the traction device and the cryogenic liquid container with the traction line, and adjust the position of the traction device and the test platform so that the two ends of the traction line are on the same axis.

[0041] (4) Fill the cryogenic liquid container with cryogenic liquid. The cryogenic temperature is transferred to the test sample and the friction pair. After the test temperature is reached and stabilized, start the traction device to drive the cryogenic liquid container to slide and record the friction force F. At the same time, record the liquid level height through the scale on the inner wall of the cryogenic liquid container. The volume of the cryogenic liquid is obtained from the liquid level height, and then the mass m2 of the cryogenic liquid is obtained. Then the friction coefficient is μ=F / [(m1+m2)g].

[0042] The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the present utility model embodiments.

[0043] Example 1

[0044] A cryogenic liquid container with external dimensions of 300mm×200mm×150mm is manufactured. Insulation plates are added to the side walls and inside of the lid to slow down the evaporation of the cryogenic liquid. No insulation plate is added to the bottom of the container to facilitate temperature conduction. A 50mm×50mm square hole is made on the lid of the cryogenic liquid container to facilitate filling with cryogenic liquid and to observe the liquid level. The inner wall of the cryogenic liquid container is engraved with graduation lines with an accuracy of 1mm. The volume of the cryogenic liquid can be determined according to the graduation lines, and then the mass of the cryogenic liquid can be calculated. A pull bar is installed 50mm away from the bottom of the cryogenic liquid container and connected to the pull ring on the traction device through a traction line.

[0045] The test sample measures 300mm×200mm×20mm and is made of glass fiber reinforced epoxy resin composite material. The friction pairs are made of steel plate and aluminum alloy plate, respectively, with dimensions of 380mm×220mm×10mm.

[0046] The traction device uses a horizontal mechanical testing machine. The machine is equipped with a pull ring with a horizontal height of 285 mm. The machine has a load range of 500 N, an accuracy of 0.1 N, a displacement stroke range of 0-150 mm, and an adjustable displacement speed range of 10-500 mm / min. Considering the height of the pull ring on the cryogenic liquid container and the thickness of the sample and friction pair, the height of the test platform is set to 205 mm, ensuring that the horizontal height of the pull ring on the cryogenic liquid container matches that on the mechanical testing machine. The test platform dimensions are 380 mm × 220 mm. The sample is fixed to the bottom of the cryogenic liquid container using screws on the side, and the friction pair is fixed to the test platform using screws on the back.

[0047] The above-mentioned apparatus was used to test the coefficient of friction of the samples against steel plates and aluminum alloys at room temperature and -25℃. The test steps are as follows:

[0048] 1. Room temperature friction coefficient test

[0049] (1) Fix the test sample to the bottom of the cryogenic liquid container with screws, and weigh the mass m1 of the cryogenic liquid container and the sample with a balance;

[0050] (2) Fix the friction pair to the test stand with screws, and fix the probes of the two thermocouples in the middle position on both sides of the friction pair with low temperature resistant glue. The temperature probe is about 5mm away from the edge of the sample. Connect the thermocouple to the temperature measuring instrument.

[0051] (3) Place the cryogenic liquid container with the sample on the friction pair, adjust the position of the sample to be centered, connect the mechanical testing machine and the cryogenic liquid container with a steel wire rope, and adjust the position of the mechanical testing machine and the test platform so that the two ends of the steel wire rope are on the same axis.

[0052] (4) Start the mechanical testing machine to drive the low-temperature liquid container to slide, record the friction force F, and the friction coefficient is μ=F / (m1g). The measurement results are shown in Table 1.

[0053] 2. Friction coefficient test at -25℃

[0054] (1) Fix the test sample to the bottom of the cryogenic liquid container with screws, and weigh the mass m1 of the cryogenic liquid container and the sample with a balance;

[0055] (2) Fix the friction pair to the test stand with screws, and fix the probes of the two thermocouples in the middle position on both sides of the friction pair with low temperature resistant glue. The temperature probe is about 5mm away from the edge of the sample. Connect the thermocouple to the temperature measuring instrument.

[0056] (3) Place the cryogenic liquid container with the sample on the friction pair, adjust the position of the sample to be centered, connect the mechanical testing machine and the cryogenic liquid container with a steel wire rope, and adjust the position of the mechanical testing machine and the test platform so that the two ends of the steel wire rope are on the same axis.

[0057] (4) Fill the cryogenic liquid container with liquid nitrogen. The low temperature is transferred to the test sample and friction pair. After the test temperature is reached and stabilized, start the mechanical testing machine to drive the cryogenic liquid container to slide and record the friction force F. At the same time, record the liquid nitrogen height through the scale on the inner wall of the cryogenic liquid container. The volume of liquid nitrogen is obtained according to the liquid level height. The mass m2 of the cryogenic liquid is obtained according to the liquid density. Then the friction coefficient is μ=F / [(m1+m2)g]. The measurement results are shown in Table 1.

[0058] Table 1. Test results of friction coefficient

[0059]

[0060] According to the test results in Table 1, the test results of the low-temperature friction coefficient and the room-temperature friction coefficient tested by this device have high consistency and uniformity.

[0061] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An apparatus for testing the coefficient of friction, characterized in that, The device includes a traction device (1), a traction line (2), a test platform (3), a friction pair (4), a test sample (5), a cryogenic liquid container (6), and a temperature measuring component. The test sample (5) is fixed at the bottom of the cryogenic liquid container (6), the friction pair (4) is fixed on the test platform (3), the friction pair (4) is located below the test sample (5), the friction pair (4) is connected to the temperature measuring component, and the temperature measuring component is used to measure the temperature at the friction interface. The traction device (1) is connected to the cryogenic liquid container (6) through the traction line (2).

2. The apparatus according to claim 1, characterized in that, The temperature measuring component includes a thermocouple (7) and a temperature measuring device (8). The thermocouple (7) is connected to the temperature measuring device (8), and the thermocouple (7) is connected to the friction pair (4).

3. The apparatus according to claim 2, characterized in that, Multiple thermocouples (7) can be installed.

4. The apparatus according to claim 2, characterized in that, Two thermocouples (7) are provided, and the two are respectively located on the side of the friction pair (4).

5. The apparatus according to claim 1, characterized in that, Both the traction device and the cryogenic liquid container are equipped with pull rings, which are connected to the traction line (2).

6. The apparatus according to claim 1, characterized in that, The cryogenic liquid container (6) is provided with an insulation layer.

7. The apparatus according to claim 1, characterized in that, The friction pair (4) is one of steel plate or aluminum alloy plate.

8. The apparatus according to claim 1, characterized in that, The traction device (1) is a horizontal mechanical testing machine.

9. The apparatus according to claim 2, characterized in that, The temperature measuring device (8) is a thermometer with a temperature measuring range of -200℃ to 200℃.

10. The apparatus according to claim 2, characterized in that, The thermocouple (7) is a type K thermocouple with a temperature measurement range of -200℃ to 200℃.

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