Axle gear set structure improvement

2020 - axle gear set structure improvement 04 - 16 we get ( Automotive technology research institute) This paper after the analysis of the failure parts to determine the failure mode, an analysis of the causes for failure mode, using the finite element simulation of existing gear set of structural strength analysis, according to the analysis result and failure on existing mesh set for the structure improvement. Determined by several rounds of simulation analysis and experimental verification, the meshing of the final optimized structure, and complete the improved structure of the switch. After statistics, the switching between the rear differential system fault claim was reduced by 50% or more, to prove the effectiveness of the improvement. 1 describe an bridge main due to the fault, by analyzing the main failure mode mainly include: reduction play tooth bevel gear, guide bearing cataclastic, differential shell connecting bolt to turn around, wear, sliding mesh set of fracture failure, etc. Analysis of old pieces of main reduction culprit: ( 1) According to each component's position within the main reduction of assembly, because the mesh set position is higher, so it has been damaged guide bearing, the passive gear pieces can't cross the differential assembly damage to the location of high mesh. （ 2) Meshing of damage, if the pieces will fall into the assembly at the bottom of the reduction, as the main by the rotation of the driven gear are driven, thus causes the damage of main reduction in other parts. When meshing sets due to reasons such as unintended use cracked after different degrees of main reducer assembly with bevel gear tooth, differential shell connecting bolt to turn around and play wear, such as guide bearing fracture failure. After feedback has 116 main reducer assembly, which indicate the mesh have a set of fracture failure, a total of 50, meshing sets of fracture is accompanied by the failure. It can be seen that the failure main concentration reduction performance is caused by the fracture after the tooth set a series of knock against, fracture damage. Thus to solve the problem of the bridge main invalidation reduction first is to address the meshing of the fracture. Main failure mode for tooth root fatigue fracture, as shown in figure 1, the crack source is located at the end tooth root ministry, about a quarter to a third from end tooth lateral teeth, along the side of tooth root fracture extend, until the spline. Figure 1 analysis according to the failure modes, failure reasons photo 2 compliance failure parts for the screen: ( 1) Fault sliding mesh end tooth root ministry set no small rounded corners, or rounded, transition, this will cause severe stress concentration, as shown in figure 2. Figure 2 roots without rounded corners, or rounded small ( 2) Meshing tooth flank contact mark uneven, generally biased towards the lateral, resulting in partial load, as shown in figure 3. Figure 3 mesh partial load and improvement measures to prevent the fatigue fracture in early stage on the sliding mesh set of end face first is to reduce the root and its around stress or improving the strength of the material, the second should prevent the partial load as much as possible. （ 1) Increase end tooth root fillet, minimize stress concentration, improve the roughness, in order to increase the root transition fillet, the depth increasing. （ 2) In view of the fixed end face gear is not matched with fracture, the transverse tooth thickness thinning appropriately, can be as far as possible to make such as strength match. （ 3) End face gear precision forging forming, assuring complete processing line, profile processing according to the drawing to reflect convex shape structure, to improve the meshing contact mark, reduce the serious phenomenon of partial load. （ 4) Root shot blasting, strengthening and the examination of the position degrees, imprinting, prevent partial load. Four finite element analysis in finite element analysis software to define a grid, sliding mesh analysis model is established, according to the actual working condition, analyze the existing structure calculation, according to the results of analysis, put forward the improvement plan. As shown in figure 4, the root fillet increase, the tooth with circumferential tendons wrapped, connected into a monolithic, better rigidity and strength. Figure 4 structure improvement ( Left now structure, right), the structure is improved As shown in figure 5, the maximum stress position and initial fracture failure parts, verify the analysis model is in conformity with the actual working condition. Figure 5 the results of the analysis ( Left now structure, right), the structure is improved Through improvement, check working conditions is in, pay attention to regional stress reduced by 15%, as shown in table 1, less than the yield strength, material mesh set of safety coefficient is greater than 1. 3. Table 1 stress contrast before and after improvement 5 test according to the meshing sets of actual working condition, our bench verification contrast, confirm the improvement scheme is effective. Table 2 number of fatigue by bench test can be concluded that under the test conditions, the improved structure through bench test and verify. Because of the improvement effect is remarkable, organization structure of the market, through after-sales data contrast, fault claim a drop in more than 50%, to achieve the improvement. 6 the conclusion in this paper, through the analysis of the service failure parts to determine the failure mode and failure cause, using the method of finite element simulation of meshing sets are analyzed and the structure improvement, through the bench test, reached the design requirements. Also performed well in the subsequent market validation. In this paper, the analysis of the results of mesh set and relevant improvement has a certain guiding role. References [ 1] ZhuYanNian. The latest axle design, manufacturing, quality inspection and standards at home and abroad practical manual. Beijing: China knowledge publishing house, 2005. ( 2] Raismes pell. Suspension components and chassis mechanics. Jilin: jilin science &technology press, 1991.