A method for characterizing the wear of bonded carbon fiber synchronizer friction rings

Abstract

The present invention provides a method for characterizing the wear of a bonded carbon fiber synchronizer friction ring. The specific steps are as follows: S1. Cutting and sampling the friction ring to be evaluated to obtain a characterization sample; S2. Using a scanning electron microscope (SEM) to observe the carbon fiber wear morphology in various regions of the characterization sample, selecting the geometric center of the carbon cloth region of the characterization sample as the region of interest; S3. Using the SEM, selecting and outlining at least one wear unit in both the horizontal and vertical directions of the region of interest, and calculating the area of ​​each selected wear unit to characterize the wear M of the friction ring carbon cloth. This method, by characterizing carbon cloth wear by wear unit area, solves the problems of low accuracy and poor consistency in the resulting data of existing methods for evaluating the wear of bonded carbon fiber synchronizers, facilitating further research into the performance of such structures.

Description

Technical Field

[0001] The invention belongs to the technical field of synchronizer carbon cloth wear characterization, and in particular to a method for characterizing the wear of a bonded carbon fiber synchronizer friction ring. Background Art

[0002] Synchronizers, a device that utilizes friction to quickly synchronize gears at different speeds, enabling smooth gear shifting, are widely used in modern automotive mechanical transmissions. Furthermore, synchronizers enable fast, accurate shifting, and easy operation, significantly extending the lifespan of the gearshift system.

[0003] Carbon fiber is widely used in synchronizer friction rings due to its excellent wear resistance, high coefficient of friction, good toughness, impact resistance, and vibration resistance. Studying synchronizer carbon cloth wear is an important indicator for predicting synchronizer performance and lifespan. Accurately measuring synchronizer wear provides more reliable test data for synchronizer research, making research on synchronizer carbon cloth wear of great significance.

[0004] The current method for characterizing the wear of this type of synchronizer is to measure the change in the synchronizer backlash. Specifically, after assembling the synchronizer friction pair, a 50N weight is placed downward to compress the synchronizer components to reduce the gap. After compression, the synchronizer backlash (synchronizer assembly height) is measured with a vernier caliper. The change in backlash after the test is the synchronizer wear. This method has two major drawbacks: 1) the inner and outer rings deflect when the weight is applied, resulting in inaccurate test data; 2) it requires a high level of operator skill, resulting in inconsistent test results between different operators. Currently, the error in characterizing wear using this method is generally around 10%. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for characterizing the wear of a bonded carbon fiber synchronizer friction ring. By characterizing the wear of the carbon cloth by the wear unit area, the method solves the problem of low accuracy and poor consistency of the result data obtained by the wear evaluation method of the bonded carbon fiber synchronizer in the industry, which is conducive to more in-depth research on the performance of such structures.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for characterizing the wear of a bonded carbon fiber synchronizer friction ring, comprising the following specific steps:

[0007] S1 cuts the friction ring to be evaluated to obtain a characterization sample;

[0008] S2 SEM scanning electron microscope observation characterizes the carbon fiber wear unit morphology in each area of ​​the sample, and the geometric center area of ​​the carbon cloth area of ​​the sample is selected as the area of ​​interest;

[0009] S3 SEM scanning electron microscope: select at least one wear unit in the horizontal and vertical directions of the area of ​​interest and outline it. Calculate the area of ​​each selected wear unit to characterize the wear amount M of the friction ring carbon cloth.

[0010] Furthermore, in S3 , the average value of the sum of the areas of the wear units is represented as the wear amount M of the friction ring carbon cloth.

[0011] Furthermore, in S1, at least two characterization samples are evenly distributed on the circumference of the friction ring, and the cutting direction is perpendicular to the circumferential direction of the outer surface of the friction ring. The width of the characterization samples is the height of the friction ring, and the length is 15 mm to 20 mm.

[0012] Furthermore, in S2, the outer surface of the friction ring on the sample is characterized by observing the wear morphology of the carbon fiber using a SEM scanning electron microscope, and the magnification of the SEM scanning electron microscope is at least 100 times.

[0013] Furthermore, in S2, the region of interest includes complete 6 to 9 wear units located in the geometric center area.

[0014] Furthermore, in S2, the lengths of the wear unit in the region of interest in the horizontal and vertical directions are determined by a scanning electron microscope (SEM), and the contours of the wear unit are outlined using a circle or an ellipse based on the length data in the horizontal and vertical directions.

[0015] Furthermore, the boundaries of the length in the transverse direction and the longitudinal direction are respectively taken to end at the last broken carbon fiber in the respective corresponding directions.

[0016] Furthermore, when the lengths of the wear unit in the region of interest in the horizontal and vertical directions are the same, the outline shape is a circle, and the area calculation formula of the circle is used to calculate the area of ​​the wear unit.

[0017] Furthermore, when the lengths of the wear unit in the region of interest are different in the horizontal and vertical directions, the outline shape is an ellipse, and the area calculation formula of the ellipse is used to calculate the area of ​​the wear unit.

[0018] Furthermore, the circumferential direction of the outer surface of the friction ring is the transverse direction, and the axial direction of the outer surface of the friction ring is the longitudinal direction.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The present invention provides a method for characterizing the wear of a friction ring of a bonded carbon fiber synchronizer. The working principle of the friction ring bonded with carbon cloth is to synchronize the speed of the input end and the output end by friction between the carbon cloth as a friction medium. The carbon cloth first wears at the high point during the friction process. As the friction ring continues to run, the wear area gradually increases. The higher the speed, the greater the moment of inertia, and the more times it is used, the greater the wear amount and the wear area. The present invention utilizes the advantages of a large depth of field and high measurement accuracy of an SEM scanning electron microscope to observe the wear of the carbon cloth on the friction ring. The wear unit can accurately outline the contour of the wear unit and accurately measure the area of ​​the wear unit, thereby realizing an intuitive expression of the wear amount M of the carbon cloth on the friction ring and eliminating the measurement error caused by the system deflection caused by the application of heavy objects in the original method. In addition, through SEM scanning electron microscopy observation, it was found that the shape of the wear unit is elliptical or circular. Relying on the existing axiomatic area formulas of circles and ellipses, the wear amount of the carbon cloth can be characterized by the area of ​​the wear unit. The calculation result is accurate, and the morphology of the carbon cloth on the friction ring before and after wear can also be observed and recorded. Based on the above characteristics, the characterization method of the present invention is more scientific, standardized and multi-dimensional.

[0021] The present invention uses a scanning electron microscope (SEM) to magnify at least 100 times during observation, so that the measurement result is more accurate. Experimental verification shows that the consistency of the carbon cloth wear amount tested by this method is within 5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Morphology of carbon cloth before use;

[0023] Figure 2 Morphology of carbon cloth after use;

[0024] Figure 3 Morphology of broken carbon fiber after use;

[0025] Figure 4 Wear unit elliptical profile;

[0026] Figure 5 Schematic diagram of the wear unit ellipse;

[0027] Figure 6 Schematic diagram of sampling locations;

[0028] Figure 7 Wear morphology of carbon cloth in single inertia and single speed test 200,000 times;

[0029] Figure 8 Wear morphology of carbon cloth at 91,000 times of triple inertia and single speed;

[0030] Figure 9 Physical picture of the sample;

[0031] Figure 10Flowchart of the method for characterizing the wear of the bonded carbon fiber synchronizer friction ring of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown in the figure, the morphology of the synchronizer friction ring carbon cloth before use is observed by SEM scanning electron microscope. The carbon cloth is made of cross-woven fiber bundles. After the synchronizer is used, the friction ring carbon cloth will wear out. Figure 2 The morphology of the synchronizer after the test was observed. It was found that the carbon fiber bundle was broken in the worn area after use (such as Figure 3 ), the shape of the wear unit is approximately circular or elliptical ( Figure 2 、 Figure 4 ), therefore, the present invention provides a method for characterizing the wear of a bonded carbon fiber synchronizer friction ring, the process is as follows Figure 10 As shown in the figure, the area of ​​the wear unit is used to characterize the wear amount of the carbon cloth. The specific steps are as follows:

[0034] 1) Press Figure 6 The black frame uses a grinding wheel cutter to cut the friction ring to be evaluated perpendicular to the outer surface of the friction ring. At least two characterization samples are evenly distributed on the circumference of the friction ring. The characterization samples are rectangular, with a width of at least the height of the friction ring and a length of about 15 to 20 mm. After cutting, the bottom (inner surface of the friction ring) is ground flat for subsequent observation. Figure 2 、 Figure 6 As shown by the arrows, the circumferential direction of the outer surface of the friction ring is marked as the transverse direction, and the axial direction of the outer surface of the friction ring is marked as the longitudinal direction. The carbon cloth on the outer surface of the friction ring is the area that needs to be characterized in the present invention.

[0035] 2) Soak the sample in alcohol or gasoline for 30 minutes, then clean it in the solution using an ultrasonic cleaner to remove oil. The purpose of soaking is to fully dissolve the oil impregnated into the carbon cloth, ensuring a thorough cleaning and preventing oil from seeping out and contaminating the electron microscope observation chamber during observation.

[0036] 3) Place the sample on a SEM scanning electron microscope, adjust the electron microscope voltage to ≥15KV, and stabilize the beam current at 100±10μA. In order to clearly observe the broken carbon fiber, the magnification is required to be at least 100 times.

[0037] 4) Observe the wear morphology of carbon fiber in each area of ​​the whole sample, take pictures of the wear morphology of carbon cloth in the area of ​​interest and record it to obtain the wear morphology map of carbon cloth in the area of ​​interest. The position of the selected area of ​​interest is specified to be located in the geometric center area of ​​the carbon cloth area of ​​the sample. Figure 9 As shown, this can ensure the relative flatness of the observation area as much as possible to improve data accuracy;

[0038] Specifically, 6 to 9 complete wear units in the geometric center area are selected.

[0039] 5) Measure the lengths of the wear unit in the region of interest in the horizontal and vertical directions under a scanning electron microscope (SEM), and use a circle or ellipse to outline the wear unit based on the horizontal and vertical length data;

[0040] Generally, the principle for determining the transverse and longitudinal lengths of each wear unit is to take the boundaries of the transverse and longitudinal lengths to the last broken carbon fiber in each corresponding direction, and then outline the contour of the wear unit based on the transverse and longitudinal length values.

[0041] 6) It is required that at least one wear unit should be selected in each horizontal and vertical direction for each region of interest to improve data accuracy, and the wear units taken in the horizontal and vertical directions should not be repeated.

[0042] 7) Data processing: Calculate the area of ​​the ellipse (or circle) in two directions outlined in the region of interest (i.e., the carbon cloth wear area), and finally calculate the average value, which is defined as the wear amount M of the carbon cloth of the friction ring.

[0043] like Figure 5 As shown, the formula for the area of ​​an ellipse is S=πab, where π is the pi, a is the major axis of the approximate wear ellipse, and b is the minor axis of the approximate wear ellipse. When a=b, it is a circle.

[0044] Characterization results: friction ring carbon cloth wear: M = xxmm 2 , keep three decimal places, and attach photos of carbon cloth wear.

[0045] Example

[0046] Two characterization samples were evenly distributed on the circumference of the friction ring and the wear was characterized using the above method. According to the "test reserve change" method currently used to characterize the wear theory of synchronizer, the wear of the synchronizer after 200,000 tests at single inertia and single speed is basically equivalent to the wear of the synchronizer after 91,000 tests at triple inertia and single speed. The test results are as follows:

[0047] Take two samples of the friction ring that has been subjected to the single speed and single inertia test for 200,000 times according to step 1 of the present invention, separated by 180 degrees. Figure 7 The wear morphology of one of the samples is shown in Figure 1. The transverse ellipse has the following characteristics: major axis a1 = 1.243 mm, minor axis b1 = 0.938 mm, and the area of ​​the wear ellipse is S = 3.663 mm. 2 Longitudinal ellipse: major axis a2 = 1.274 mm, minor axis b2 = 1.034 mm, wear ellipse area S = 4.138 mm 2 The average area in the two directions is: S = 3.901mm 2 .

[0048] The dimensions of the wear unit of another sample are as follows: transverse ellipse: major axis a1 = 1.194 mm minor axis b1 = 0.989 mm, wear ellipse area S = 3.710 mm 2 Longitudinal ellipse: major axis a2 = 1.052 mm, minor axis b2 = 1.044 mm, wear ellipse area S = 3.450 mm 2 The average area in the two directions is: S = 3.450mm 2 .

[0049] In summary, the wear of the friction ring after 200,000 times of single speed and single inertia test is M = (3.901 + 3.450) / 2 = 3.676 mm 2 .

[0050] For the friction ring that has been subjected to the triple inertia single speed test 91,000 times, two samples are taken 180° apart according to step 1 of the present invention. Figure 8 The wear morphology of one of the samples is a transverse ellipse with a major axis a1 = 1.268 mm, a minor axis b1 = 0.928 mm, and an area S = 3.697 mm. 2 Longitudinal ellipse: major axis a2 = 1.123 mm, minor axis b2 = 0.999 mm, S = 3.524 mm 2 The average area in the two directions is: S = 3.611mm 2 .

[0051] The dimensions of the other sample wear unit are as follows: transverse ellipse: major axis a1 = 1.298 mm, minor axis b1 = 0.867 mm, area S = 3.535 mm 2 Longitudinal ellipse: major axis a2 = 1.062 mm, minor axis b2 = 1.049 mm, S = 3.500 mm 2 The average area in the two directions is: S = 3.518mm 2 .

[0052] In summary, the wear amount of the friction ring after 91,000 times of triple inertia and single speed test is M = (3.611 + 3.518) / 2 = 3.564 mm 2 .

[0053] The test found that the standard deviation of the friction ring wear M in the two tests was about 0.0792mm. 2 The deviation value accounts for about 2.5% of the wear of the two friction rings. The deviation is small and the result is highly reliable. The accuracy of this method is verified.

[0054] The application prospects of the characterization method of the present invention are mainly reflected in the following aspects:

[0055] 1. A horizontal comparison of the wear of different friction ring carbon cloths under different test conditions shows that there is little difference in the wear amount between the 200,000-time wear test of single-speed and single-inertia test and the 91,000-time wear test of triple-inertia and single-speed test. Therefore, the design and improvement of the synchronizer test method can be carried out by comparing the wear amount, shortening the test cycle, which not only helps product design, but also saves test resources and reduces test costs.

[0056] 2. Under given test conditions, it can be determined whether the wear amount of the carbon cloth in this test meets the requirements.

Claims

1. A method for characterizing the wear of a bonded carbon fiber synchronizer friction ring, characterized in that: The specific steps are as follows: S1 cuts the friction ring to be evaluated to obtain a characterization sample; S2 SEM scanning electron microscope observation characterizes the carbon fiber wear unit morphology in each area of ​​the sample, and the geometric center area of ​​the carbon cloth area of ​​the sample is selected as the area of ​​interest; S3 Select at least one wear unit in both the horizontal and vertical directions of the region of interest under a SEM scanning electron microscope and outline it. Calculate the area of ​​each selected wear unit to characterize the wear amount M of the friction ring carbon cloth. In S2, the lengths of the wear unit in the horizontal and vertical directions in the region of interest are determined by SEM scanning electron microscopy, and the contours of the wear unit are outlined using a circle or an ellipse based on the length data in the horizontal and vertical directions; The boundaries of the length in the transverse and longitudinal directions are respectively taken to the last broken carbon fiber in the corresponding direction; When the lengths of the wear unit in the region of interest are the same in the horizontal and vertical directions, the outline shape is a circle, and the area calculation formula of the circle is used to calculate the area of ​​the wear unit; When the lengths of the wear unit in the region of interest are different in the horizontal and vertical directions, the outline shape is an ellipse, and the area calculation formula of the ellipse is used to calculate the area of ​​the wear unit.

2. The method for characterizing the wear of a bonded carbon fiber synchronizer friction ring according to claim 1, characterized in that: In S3, the average value of the sum of the areas of the wear units is represented as the wear amount M of the friction ring carbon cloth.

3. The method for characterizing the wear of a bonded carbon fiber synchronizer friction ring according to claim 1, characterized in that: In S1, at least two characterization samples are evenly distributed on the circumference of the friction ring. The cutting direction is perpendicular to the circumferential direction of the outer surface of the friction ring. The width of the characterization sample is the height of the friction ring, and the length is 15 mm to 20 mm.

4. The method for characterizing the wear of a bonded carbon fiber synchronizer friction ring according to claim 1, characterized in that: In S2, the outer surface of the friction ring on the characterization sample is the area where the carbon fiber wear morphology is observed by SEM scanning electron microscopy, and the magnification of the SEM scanning electron microscope is at least 100 times.

5. The method for characterizing the wear of a bonded carbon fiber synchronizer friction ring according to claim 1, characterized in that: In S2, the region of interest includes the complete 6 to 9 wear units located in the geometric center area.

6. A method for characterizing the wear of a bonded carbon fiber synchronizer friction ring according to any one of claims 1 to 5, characterized in that: The circumferential direction of the outer surface of the friction ring is the horizontal direction, and the axial direction of the outer surface of the friction ring is the longitudinal direction.

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