Surfaces Of Spiral Bevel Gears Research Articles

Mathematical modeling and numerical simulation for determining an optimized oil jet layout for spiral bevel gear lubrication

In aeroengine industry, the oil jet layout significantly influences lubrication of high-speed and heavy-load transmission gears, as there is only extremely limited meshing clearance for the oil stream jetting into and an inevitable blocking effect of rotating gears. A novel mathematical model for calculating the exact impingement depth of the lubrication oil jet on the spiral bevel gear surface has been established, and it contains comprehensive and detailed design parameters for the jet nozzle layout and meshing gears. Furthermore, under different jet layout parameters conditions, computational fluid dynamic numerical simulations for oil jet lubrication of an aeronautical spiral bevel gear pair were conducted and, then, the simulation results are compared with the impingement depths based on the mathematical model. The simulation results reveal that the oil volume fraction and oil pressure on the meshing area increase with the impingement depth, validating the effectiveness and reliability of the method using the impingement depth mathematical model for evaluating oil jet lubrication. Optimized oil jet layout parameters including the jet nozzle position, jet elevation angle, and jet azimuth angle have been determined and recommended, and they provide valuable theoretical design methods and technical guidance for oil jet lubrication optimization for various practical high-speed and heavy-load spiral bevel gears.

Microstress cycle and contact fatigue of spiral bevel gears by rolling-sliding of asperity contact

The rolling contact fatigue (RCF) model is commonly used to predict the contact fatigue life when the sliding is insignificant in contact surfaces. However, many studies reveal that the sliding, compared to the rolling state, can lead to a considerable reduction of the fatigue life and an excessive increase of the pitting area, which result from the microscopic stress cycle growth caused by the sliding of the asperity contact. This suggests that fatigue life in the rolling-sliding condition can be overestimated based only on the RCF model. The rubbing surfaces of spiral bevel gears are subject to typical rolling-sliding motion. This paper aims to study the mechanism of the micro stress cycle along the meshing path and provide a reasonable method for predicting the fatigue life in spiral bevel gears. The microscopic stress cycle equation is derived with the consideration of gear meshing parameters. The combination of the RCF model and asperity stress cycle is developed to calculate the fatigue life in spiral bevel gears. We find that the contact fatigue life decreases significantly compared with that obtained from the RCF model. There is strong evidence that the microscopic stress cycle is remarkably increased by the rolling-sliding motion of the asperity contact, which is consistent with the experimental data in previous literature. In addition, the fatigue life under different assembling misalignments are investigated and the results demonstrate the important role of misalignments on fatigue life.

A New Method of Designing the Tooth Surfaces of Spiral Bevel Gears With Ruled Surface for Their Accurate Five-Axis Flank Milling

The advantages of the five-axis flank milling of (developable) ruled surfaces include that (1) the machined surfaces could be very accurate and smooth and (2) the machining efficiency is high. Currently, spiral bevel gears are machined on the machine tools specially used for gear manufacturing. The disadvantages are that the cost is high for small batch, prototype, or repair. If a small group of spiral bevel gears are needed, the current methods are not valid. Thus, it is expected to machine the gears on five-axis computer numerical control (CNC) milling centers. Unfortunately, when tooth surfaces are designed based on the conventional gear manufacturing methods, they cannot be accurately machined in five-axis flank milling. This work is to develop the new technique for the five-axis flank milling of spiral bevel gears. First, a new method of designing the tooth surface of spiral bevel gears with ruled surface is proposed. Second, the cutter locations and orientations are calculated for five-axis flank milling the tooth surfaces. Third, the actual tooth surfaces are accurately represented with the cutter envelope surface in five-axis flank milling. It is confirmed that the difference of the actual tooth surface and the designed tooth surface is within the tolerance. Then, a pinion is generated to mesh with the gear, and the tooth contact analysis (TCA) is conducted. The good result demonstrates that the proposed method is valid, thus it can be used in industry.

Roughness model for tooth surfaces of spiral bevel gears under grinding

A mathematical model of grinding roughness for spiral bevel gears is proposed. The model considers two sources that contribute to the roughness, (i) material removal, and (ii) the discretized generating movement between the grinding wheel and the workpiece. For source (i), the classical roughness model for general orthogonal grinding is adopted, for which the grinding process of spiral bevel gears is reviewed in a new framework to extract necessary parameters. With the proposed model, roughness can be calculated as a distribution over the gear surface. An example is presented to show the process, based on which several measures to optimize the grinding parameters are discussed.

Surface Quality and Accuracy Characteristics of Spiral Bevel Gear by Electrochemical Mechanical Finishing

Spiral bevel gears (SBG) are the core transmission elements for realizing intersection shaft driving. Owing to the outstanding advantages of finishing efficiency and capability, electrochemicalmechanical finishing (ECMF) is used to finish the tooth surfaces of SBG for improving surface quality and accuracy.The forming ECMFmethod is put forward, the influence of processing parameters on the surface roughness is studied, and the influence of the forming ECMF method on the accuracy of SBG’s tooth profile is studied experimentally. The results indicate that the surface roughness R a is reduced from 1.6 μm to 0.05 μm. After finishing, the dimensional accuracy between teeth can be enhanced by 1∼2 grades compared with the technical specifications before finishing and the accuracy of gear teeth profile are also improved.

Simulation Analysis of Spiral Bevel Gear Tooth Surface Generation Based on VERICUT

Based on the deeply study on VERICUT, the generating process of spiral bevel gear surface is simulated in this paper. A certain surface generation process of spiral bevel gear is analyzed as an example. First the 3D solid models of gear cutting machine, cutter and gear blank are built. Then the NC program is compiled based on the generating principle of tooth surface. Finally the surface generating movement of spiral bevel gear is realized through selecting control system and importing the NC program. It can be indicated that the simulation analysis of surface generation can optimize the cutting movement and provide theoretical basis for the movement analysis of gear cutting.