Automobile cylindrical gear is the main component to transmit driving power. Its wear resistance directly affects the service life of cylindrical gear. Because the automobile cylindrical gear transmission itself has the characteristics of strong repeatability and continuous work, and under the action of cyclic alternating stress, its tooth surface meshing area is often worn seriously, resulting in tooth surface fatigue failure, pitting, gluing and other phenomena, reducing the service life of the cylindrical gear and affecting the normal operation of the automobile. Based on the theory of bionics, combined with cylindrical gear tribology and bionic tribology, starting with the model test, this paper optimizes the pit bionic shape with relatively wear resistance, processes it onto the test cylindrical gear, carries out the fatigue wear comparison test of smooth cylindrical gear and pit bionic cylindrical gear, and completes the two-dimensional and three-dimensional finite element numerical simulation of model sample and test cylindrical gear, The following conclusions are obtained:
- According to the characteristics of cylindrical gear meshing transmission, the transmission of cylindrical gear is simplified into the motion form of two cylinder surfaces with relatively small sliding and meshing rolling. The micro pit shape on the surface of the ring block sample with different pit diameter and spacing distribution is optimized and designed; Using ct-200ii numerical control laser engraving machine, the designed concave bionic shape is formed on the surface of the ring sample; Using M-200 friction and wear testing machine, the wear properties of ring samples with smooth shape and 9 kinds of pit bionic shape were compared; Through the measurement results of the overall quality before and after the test, the wear amount and wear rate of 10 ring block samples before and after the test are obtained. It is compared that under the lubrication state, the wear amount and wear rate of 9 bionic ring block samples are less than that of smooth ring block samples, indicating that the ring block samples with concave bionic surface are more smooth and wear-resistant than that of smooth ring block samples. Among them, the ring block samples with No. 6 concave bionic surface have the lowest wear amount and wear rate, The order of wear resistance is 6 > 5 > 4 > 9 > 7 > 8 > 3 > 1 > 2. Using orthogonal experimental design, the range analysis of wear amount and wear rate of pit bionic ring samples is carried out. It is found that the primary and secondary factors affecting the wear amount of pit ring samples are: a (pit diameter) > b (transverse center distance) > C (longitudinal center distance), the optimal levels are A2, B3 and C1 respectively, and the optimal combination is a2b3c1. The order of primary and secondary factors shows that the diameter of pits has the greatest influence on the wear amount, the transverse spacing of pits takes the second place, and the longitudinal spacing of pits has the least influence; The sequence of superior level shows that the pit diameter is 100 μ m. The transverse spacing of pits is 450 μ m. The wear resistance is the best when the longitudinal spacing of pits is 350. The test shows that the wear resistance can be improved by 41%.
- Based on the finite element analysis method of contact problem, using ANSYS finite element analysis software, the three-dimensional finite element numerical simulation of contact problem of smooth ring block sample and concave bionic ring block sample without lubrication is carried out. Through a series of steps such as setting the element type, defining the material attribute, dividing the grid, defining the contact and loading setting, the contact force between the smooth ring block sample and 9 kinds of concave bionic ring block samples is obtained; The corresponding equivalent stress and contact stress distribution nephogram are obtained by using ANSYS post-processing tool. By comparing the stress numerical results of smooth ring block sample and nine pit type samples, it is concluded that under the condition of no lubrication, the contact equivalent stress and stress intensity of No. 1 ring block sample is the smallest, the contact stress of No. 9 ring block sample is the smallest, and the contact penetration of No. 3 and No. 9 ring block sample is the smallest, The contact equivalent stress, stress intensity, contact stress and contact penetration of sample 7 are the largest.
- A comparative experimental study on the wear resistance of smooth and concave bionic cylindrical gears was carried out by using the cylindrical gear fatigue wear tester. By measuring the shape parameters of the tooth surface before and after the cylindrical gear test, the error curves and error values of the tooth direction error and tooth shape error before and after the cylindrical gear test are obtained. Comparing the error value curves of tooth alignment error and tooth profile error before and after the smooth shape large and small gear test, it can be seen that after the test, the two error lines on the right side of the gear become uneven, the tooth alignment error line presents an uneven wave distribution, and the tooth profile error line has a serious depression in the middle position, which is the contact surface area of the cylindrical gear, indicating that this area is seriously worn; The error value curve of the tooth direction error of the concave bionic cylindrical gear changes relatively little, and the middle of the tooth shape error line is only slightly concave, indicating that the wear of the contact area of the concave cylindrical gear is light. Comparing the error values before and after the test, it can also be seen that the tooth direction error value and tooth shape error value of the smooth cylindrical gear after the test increase significantly, while the relative change of the error value of the concave bionic cylindrical gear is small, which also shows that the wear resistance of the cylindrical gear with the concave bionic shape is better than that of the smooth cylindrical gear, and the bionic cylindrical gear can improve the wear resistance by 58%.
- The two-dimensional solid model of cylindrical gear is established by using CAXA electronic drawing board. The two-dimensional numerical simulation of smooth and concave bionic cylindrical gear contact is completed by using ANSYS finite element analysis software, and the comparative analysis of its contact equivalent stress and contact stress is carried out. Comparing the distribution and size of equivalent stress and contact stress of smooth and concave cylindrical gears, it is concluded that the maximum values of equivalent stress and contact stress of the two cylindrical gears appear at the contact position between the tooth top of the big gear and the tooth root of the small gear, and the equivalent stress and contact stress of the contact area of the tooth surface of the concave bionic cylindrical gear are lower than that of the smooth cylindrical gear.
- The three-dimensional solid model of cylindrical gear is established by CATIA drawing software. The three-dimensional numerical simulation of contact between smooth and concave bionic cylindrical gear is completed by using ANSYS finite element analysis software, and the comparative analysis of equivalent stress and contact stress of two kinds of cylindrical gears is carried out. By comparing the distribution and size of equivalent stress and contact stress of smooth and concave cylindrical gears, it is concluded that the maximum values of equivalent stress and contact stress of the two cylindrical gears appear at the contact position between the top of the big gear and the root of the small gear, and the equivalent stress and contact stress in the contact area of the tooth surface of concave bionic cylindrical gear are lower than that of smooth cylindrical gear.
- According to the elastohydrodynamic lubrication theory of gears, the numerical calculation of elastohydrodynamic lubrication contact problem of smooth and concave bionic gears is carried out by using MATLAB software. The results show that the oil film thickness between the contact surfaces of the concave bionic gear is significantly greater than that of the smooth gear, and the corresponding oil film pressure is less than that of the smooth gear. It shows that there is a thick oil film gap in the contact surface area of the concave bionic gear under lubrication, which can reduce the oil film pressure between the gears and reduce the contact stress of the gear meshing contact.