A device and method for connecting rod axial transverse fatigue test

Abstract

The present invention discloses a device and method for axial transverse fatigue test of connecting rods, which are mainly used for testing the axial tension, pressure and transverse bending fatigue performance of engine connecting rods. Main technical scheme: on the experimental platform, the left and right columns are fixed, the upper and lower beams are fixed on the upper and lower columns respectively, and a back plate is installed on the right column to form a frame; the upper part of the clamping mechanism is fixedly connected with the screw rod, and the lower part is connected with the axial piston push-pull rod; the transverse force actuator cylinder is installed on the connecting plate, and the piston of the transverse force actuator cylinder is connected to the push rod, and the push rod end faces the center of mass area of ​​the connecting rod. The present invention has been proved through trial use: it fundamentally overcomes the phenomenon that only axial tension and pressure fatigue tests can be carried out, and realizes the simultaneous axial tension, pressure and transverse bending fatigue tests of the connecting rod, so as to provide comprehensive and objective test basis to professional factories and research institutions, and better serve the research and development and production of connecting rods.

Description

Technical Field

[0001] The invention relates to an engine connecting rod fatigue reliability test method, which is mainly used for testing the connecting rod axial tension, pressure and transverse bending fatigue performance to verify whether the connecting rod fatigue performance meets the performance requirements of the connecting rod product. Background Art

[0002] Connecting rod is the core component of the engine (see Figure 1 ), consists of connecting rod body A, connecting rod cover B, and connecting rod bolt C. Before design, trial production and installation, the connecting rod must be subjected to a single fatigue test to assess and verify the fatigue reliability of the connecting rod. The current connecting rod fatigue test is carried out in accordance with the national standard GB / T3075-2008, the axial force fatigue test method for metal materials, that is, an axial sinusoidal wave alternating load force test is applied on the axis connecting line of the large and small head holes of the connecting rod. This state simulates the working state of the connecting rod when the crankshaft angle and the connecting rod swing angle are both zero degrees, with the large and small head hole forces of the connecting rod as the action points. , assess the connecting rod's ability to withstand 10 million times (one time is a sine wave cycle) of axial force, measure the connecting rod's ability to withstand alternating tension and compression loads, test to determine the connecting rod's load value without breaking and the load value of breaking, calculate the connecting rod's safety factor under a 50% survival rate load according to the standard (test load value divided by theoretical load value equals safety factor), according to technical requirements, when the safety factor is greater than or equal to 1.6, the connecting rod sample fatigue test is judged to be qualified, when the safety factor is less than 1.6, the connecting rod sample fatigue test is judged to be unqualified.

[0003] This test method is a fatigue test method for connecting rod axial force, which can only be a fatigue test for axial force. The defect is that the test is not conducted based on the actual situation of the connecting rod running in the engine, that is, there is no force when the connecting rod large hole rotates 360 degrees around the crankshaft and the connecting rod small hole swings around the piston pin, and the inertial force generated by the connecting rod mass. It also cannot reflect the real cause of the connecting rod failure. In practice, according to statistics from the main engine factory, most of the connecting rod breakage phenomena are concentrated in the process of the connecting rod body bending first and then breaking. Therefore, the data or results obtained lack accurate objective basis, which brings a great difficulty to the engine connecting rod failure analysis. This problem is a very important technical problem for our professional manufacturers and research institutions. Summary of the invention

[0004] The main technical problems and purposes to be solved by the present invention are: in view of the defects of the existing fatigue test methods, a method for axial and lateral fatigue testing of connecting rods is provided, and the axial tension, pressure and lateral bending fatigue performance tests of the connecting rods are carried out simultaneously, thereby replacing the original connecting rod fatigue test method, fundamentally overcoming the phenomenon that only axial tension and pressure fatigue performance tests can be carried out, so as to provide comprehensive and objective test basis to professional factories and research institutions, and serve the research and development and production of connecting rods.

[0005] The main technical scheme of the present invention is as follows: the device comprises a lower beam, a first bolt, a sleeve, a push rod, a piston sleeve, a connecting plate, a back plate, a second bolt, a lateral force actuating cylinder, an upper cover, a small hole core shaft, an upper seat, a right column, a connecting screw, an upper beam, a nut, a third bolt, a left column, a lower cover, a large hole core shaft, a lower seat, an axial piston push-pull rod, an axial force actuating cylinder, an experimental platform, an oil pressure station, and a controller. The specific structure is that on the experimental platform, the left column and the right column are fixedly connected by threads, the lower parts of the two columns are fastened with the first bolts through the holes of the lower beam, the upper parts of the two columns are fixedly installed with the upper beam by the third bolts, a back plate is installed on the right column by screws, and the side of the back plate is equipped with the second bolt, thus forming an apparatus. The main frame of the device is arranged; the upper support is composed of an upper seat, an upper cover and a small hole core shaft through a third bolt, and the lower clamp is composed of a lower cover and a lower seat through a third bolt, and the upper and lower clamps are combined to form a clamping mechanism; the upper part of the clamping mechanism is connected with a connecting screw, and the connecting screw passes through the upper beam and is locked and fixed with a nut, and the lower part of the clamping mechanism is threadedly connected with the axial piston push-pull rod, and the axial piston push-pull rod passes through the sleeve and is then connected to the piston of the axial force actuating cylinder; the lateral force actuating cylinder is installed on the connecting plate through a second bolt, and the piston of the lateral force actuating cylinder is connected to the push rod, and the push rod end faces the connecting rod center of mass area D; the oil pipes and power information lines of the axial force actuating cylinder and the lateral force actuating cylinder are respectively connected to the oil pressure station and the controller.

[0006] The present invention has been proved through practical application that: the research and development purpose is fully achieved, and during the research and development and production process, two connecting rod fatigue tests with different requirements are completed at the same time, and the actual position of the connecting rod fatigue test sample fracture can be displayed. The effect is closer to the actual situation of the connecting rod operation, and the test result data is more reliable; the device used has a simple structure and is easy to operate, which improves the efficiency of the connecting rod fatigue test and reduces the cost; in reality, samples taken from each batch of products are qualified through the test of the present invention, and these products have no fracture or bending when working after leaving the factory. There is no doubt that the test is objective and effective, and has made contributions to the research and development and production of engine connecting rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0008] Figure 1 , is a schematic diagram of the connecting rod assembly.

[0009] Figure 2 , is a schematic diagram of a failed bent connecting rod.

[0010] Figure 3 , which is a schematic diagram of the main structure of the present invention.

[0011] Figure 4 ,yes Figure 3 AA section diagram of .

[0012] Figure 5 , is a schematic diagram of the axial force actuator output applying an axial sinusoidal alternating load.

[0013] Figure 6 , is a schematic diagram of the transverse half-wave sinusoidal alternating load applied to the output of the transverse force actuator. DETAILED DESCRIPTION

[0014] Reference Figure 3 , 4 The main technical scheme of the present invention is described as follows: the method is mainly improved on the basis of the original engine connecting rod axial fatigue test, and a test device for the axial tension, pressure and lateral bending fatigue performance of the connecting rod is designed. At the same time, the operation steps are also designed in combination with the test device, which are described below: the test device includes a lower beam 1, a first bolt 2, a sleeve 3, a push rod 4, a piston sleeve 5, a connecting plate 6, a back plate 7 (behind the connecting plate), a second bolt 8, a lateral force actuator 9, and an upper cover 10. , small hole core shaft 11, upper seat 12, right column 13, connecting screw 14, upper beam 15, nut 16, third bolt 17, left column 18, lower cover 19, large hole core shaft 20, lower seat 21, axial piston push-pull rod 22, axial force actuator 23, experimental platform 24, oil pressure station, controller, specific structure: on the experimental platform 24, the left column 18 and the right column 13 are connected by threaded fixing, the lower part of the two columns passes through the hole of the lower beam 1 and is fastened with the first bolt 2, and the upper part of the two columns passes through the third The upper beam 15 is fixedly installed by bolts 17, a back plate 7 is installed on the right column by screws, and a second bolt 8 is installed on the side of the back plate, thus forming the main frame of the device; the upper seat 12, the upper cover 10 and the small hole core shaft 11 are composed of an upper clamp through a third bolt 17, and the lower cover 19 and the lower seat 21 are composed of a lower clamp through a third bolt 17. The upper and lower clamps are combined to form a clamping mechanism, and the upper part of the clamping mechanism is connected to the connecting screw 14, and the connecting screw passes through the upper beam 15 and is locked and fixed with a nut 16. The part is threadedly connected with the axial piston push-pull rod 22, and the axial piston push-pull rod passes through the sleeve 3 and is then connected to the piston of the axial force actuating cylinder 23; the lateral force actuating cylinder 9 is installed on the connecting plate 6 through the second bolt 8, the piston of the lateral force actuating cylinder 9 is connected to the push rod 4, and the push rod end faces the connecting rod center of mass area D; the oil pipes and power information lines of the axial force actuating cylinder 23 and the lateral force actuating cylinder 9 are respectively connected to the oil pressure station and the controller (integrated control system, including relevant load signal feedback and data processing and display).

[0015] The lateral force actuating cylinder 9 is purchased from the market, with the standard number of 25KN (EHSG25 / 33-25); the axial force actuating cylinder 23 is purchased from the market, with the standard number of 250KN (EHSG160 / 100-150); and the controller is purchased from the market, with the standard number of FxexTest40.

[0016] Reference Figure 3 , 4 , according to the test technical parameters provided by different connecting rod designs, the test is carried out. First, the two lower covers 19 and the upper cover 10 are opened, and the large-hole mandrel 20 and the small-hole mandrel 11 corresponding to the test sample are installed on the holding mechanism E, and then the test operation steps of the present invention are started:

[0017] a. Installation of test samples (see Figure 1 ), loosen the connecting rod bolt C and the connecting rod cover B, insert the large hole mandrel 20, tighten the connecting rod bolt (torque is 28-45N.m), then insert the small hole mandrel 11, and fix it with the lower cover 19 and the upper cover 10;

[0018] b. Debug the lateral force actuator. Adjust the lateral force actuator 9 and the push rod 4 to an angle of 15° with the horizontal. 0 , make the front end face of the push rod contact with the outer side of the connecting rod mass center area D (no gap), and tighten the second bolt 8 after debugging;

[0019] c. Input and set the test load. In the controller of the device, input the axial test load and the lateral test load respectively. The axial test load includes the theoretical load amplitude, average load value and test frequency, and the lateral test load includes the load amplitude, average load value and test frequency. After inputting the parameters, set the test emergency stop control program. When the sample is displaced axially by more than 1mm or compressed by more than 1mm, it will automatically stop. When the sample is displaced axially by more than 2mm, it will automatically stop. During the test, the controller controls the axial force actuator 23 and the lateral force actuator 9 to start and run synchronously.

[0020] d. The test is stopped. After the sample has been fatigue cycled for 10 million times, the machine is shut down. The horizontal push rod 4 is retracted to break away from the contact with the sample. The oil pressure is turned off. The fixture fastening bolts are unscrewed respectively. The sample is taken out and the test data is recorded.

[0021] e. Test data processing: 9 connecting rods of each specification are selected from each batch (1,200 for R&D and 12,000 for batch production), one of which is the first test product, and the remaining 8 are divided into four groups as formal test samples. Each group of samples must be tested one by one;

[0022] f. Take the sum of the actual fatigue load amplitudes of the four groups of breaks and the continuous breaks and divide it by 8 to get the average value, which is used as the 50% survival rate test load amplitude;

[0023] g. 50% survival rate test safety factor S, S = test load amplitude divided by theoretical load amplitude;

[0024] h. When S is greater than 1.6, the sample and the batch of connecting rod products are qualified; when S is less than 1.6, the sample and the batch of connecting rod products are unqualified.

[0025] The axial average load, theoretical load amplitude and frequency parameters are given according to design technical requirements; the lateral average load, load amplitude and frequency parameters are given according to design technical requirements and experience; usually the lateral average load is 5kN-10kN, and the load amplitude is 0kN.

[0026] Embodiment 1 (see Figure 3 , 4 ), the present invention is used for axial lateral fatigue test of 462QA connecting rod sample, a, install the sample on the clamping mechanism E; b, debug the lateral force actuator cylinder, adjust the lateral force actuator cylinder 9 and the push rod 4 to 15 degrees with the horizontal 0 Around, make the front end face of the push rod contact with the outer side of the center of mass area D of the connecting rod body; c. Input the twice of the theoretical axial load amplitude of the connecting rod sample ±21kN, that is, ±42kN, the average load -6kN and the frequency 20Hz into the controller of the device, and input the lateral load amplitude 0kN, the average load +8kN and the frequency 20Hz into the controller of the device; d. Use the axial load amplitude of ±42kN as the test load value of the first sample. The test results show that the sample broke after 2.34 million fatigue cycles; e. Reduce 2kN from the initial load of ±42kN, and the load amplitude is ±40kN. Then conduct the second sample test, and the result is that ±40kN breaks; reduce 2kN from the initial load of ±40kN, and the load amplitude is ±38kN. , and then the third sample was tested, the result was ±38kN without breaking, so if it was broken, subtract 2kN, if it was not broken, add 2kN, and test one by one, except the first one, test up to the eighth, four groups, namely ±40kN broken / ±38kN not broken, ±40kN broken / ±38kN not broken, ±40kN broken / ±38kN not broken, ±40kN broken / ±38kN not broken; f, take the average value of the actual fatigue load amplitudes of the four groups of broken and unbroken, that is, ±39kN, as the load amplitude of the 50% survival rate test; g, 50% survival rate test safety factor S, S=the load amplitude obtained in the test ±39kN divided by the theoretical load value ±21kN=1.85; h, the safety factor S is greater than 1.6, the sample and the batch of connecting rod products are qualified.

[0027] Embodiment 2 (see Figure 3 , 4 ), ES600 connecting rod sample axial lateral fatigue test, a, install the sample on the clamping mechanism E; b, debug the lateral force actuator, adjust the lateral force actuator 9 and the push rod 4 to 15 degrees with the horizontal 0c. Input the connecting rod sample's axial theoretical load amplitude of ±18kN, which is twice ±36kN, average load -6kN and frequency 20Hz, into the device's controller, and input the lateral load amplitude of 0kN, average load +8kN and frequency 20Hz into the device's controller; d. Use the axial load amplitude of ±36kN as the test load value for the first sample. The test results show that the sample broke after 1.14 million fatigue cycles; e. Reduce the load amplitude of 2kN from the initial load of ±36kN to ±34kN, and then conduct a second sample test. If ±34kN is not broken, add 2kN to 34kN, and the load amplitude is ±36kN. The third sample was tested and the result was that ±36kN broke. Therefore, if it broke, subtract 2kN, and if it was not broken, add 2kN. The tests were carried out one by one, except the first one, up to the eighth, four groups, namely ±36kN broken / ±34kN not broken, ±36kN broken / ±34kN not broken, ±36kN broken / ±34kN not broken, ±36kN broken / ±34kN not broken. f. The average value of the actual fatigue load amplitudes of the four groups of broken and unbroken, namely ±35kN, was taken as the load amplitude of the 50% survival rate test; g. The safety factor S of the 50% survival rate test, S=the load amplitude obtained in the test ±35kN divided by the theoretical load value ±18kN=1.94; h. The safety factor S is greater than 1.6, and the sample and the batch of connecting rod products are qualified.

[0028] The present invention has been put into the test of various connecting rods, and the effect is good, so they will not be listed one by one.

Claims

1. A method for axial transverse fatigue test of a connecting rod, wherein the device used in the axial transverse fatigue test method of a connecting rod comprises: a lower beam (1), a first bolt (2), a sleeve (3), a push rod (4), a piston sleeve (5), a connecting plate (6), a back plate (7), a second bolt (8), a transverse force actuator (9), an upper cover (10), a small hole core shaft (11), an upper seat (12), a right column (13), a connecting screw (14), an upper beam (15), a nut (16), a third bolt (17 ), left column (18), lower cover (19), large-hole mandrel (20), lower seat (21), axial piston push-pull rod (22), axial force actuator (23), experimental platform (24), oil pressure station, controller, specific structure, on the experimental platform (24), the left column (18) and the right column (13) are connected by threaded fixing, the lower part of the two columns passes through the hole of the lower beam (1) and is fastened with the first bolt (2), the upper part of the two columns is fixedly installed on the upper beam (15) by the third bolt (17), and the right column A back plate (7) is installed on the column by screws, and a second bolt (8) is installed on the side of the back plate, thus forming the main frame of the device, which is composed of an upper seat (12), an upper cover (10) and a small hole core shaft (11), and an upper clamp is formed by a third bolt (17). The lower cover (19) and the lower seat (21) are combined to form a lower clamp through the third bolt (17). The upper and lower clamps are combined to form a clamping mechanism. The upper part of the clamping mechanism is connected to a connecting screw (14), and the connecting screw passes through the upper beam (15) and is locked and fastened with a nut (16). The lower part of the clamping mechanism is threadedly connected to the axial piston push-pull rod (22), the axial piston push-pull rod passes through the sleeve (3) and is then connected to the piston of the axial force actuating cylinder (23), the transverse force actuating cylinder (9) is installed on the connecting plate (6) through the second bolt (8), the piston of the transverse force actuating cylinder (9) is connected to the push rod (4), the push rod end faces the connecting rod mass center area (D), and the oil pipes and power information lines of the axial force actuating cylinder (23) and the transverse force actuating cylinder (9) are respectively connected to the oil pressure station and the controller; The method for connecting rod axial transverse fatigue test is characterized by: The test operation steps are as follows: a. Installation of the test sample: loosen the connecting rod bolt (C) and the connecting rod cover (B), insert the large hole core shaft (20), tighten the connecting rod bolt, insert the small hole core shaft (11), and fix it with the lower cover (19) and the upper cover (10); b. Debugging of the lateral force actuator: adjust the lateral force actuator (9) and the push rod (4) to 15° with the horizontal, so that the front end surface of the push rod contacts the outer side of the connecting rod center of mass area (D). After debugging, tighten the second bolt (8); c. Input and set the test load: input the axial test load and the lateral test load in the controller of the device respectively. The axial test load includes the load amplitude, average load value and test frequency, and the lateral test load includes the load amplitude, average load value and test frequency. Test frequency. After inputting the parameters, set the test emergency stop control program. When the sample is displaced axially by more than 1mm or compressed by more than 1mm, it will automatically stop. When the sample is displaced axially by more than 2mm, it will automatically stop. During the test, the controller controls the axial force actuator (23) and the lateral force actuator (9) to start and run synchronously. d. Test stop. After the sample has been fatigue cycled for 10 million times, it will stop. The push rod (4) will be withdrawn to break away from the contact with the sample. The oil pressure will be turned off. The clamp fastening bolts will be unscrewed respectively. The sample will be taken out and the test data will be registered. e. Test data processing. Nine connecting rods of each specification are drawn out in each batch. One of them is the first test product. The remaining eight are divided into four groups as formal test samples. Each group of samples must be tested one by one.

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