Gearbox Design Research Articles

High-ratio planetary gearbox with EC gearing for robot applications

AbstractThe drive system of robots and robot-like systems (RLS) is often designed with a combination of an e-motor and a gearbox with a high transmission ratio to optimize performance. The various types of possible robot gearboxes can be selected based on their characteristics, which strongly influence the performance of the entire robotic system. Planetary gear drives have advantages due to their high efficiency and low design complexity. Disadvantageous is the low transmission ratio per stage and the resulting large design space required with the currently predominant involute gearing. Using special tooth profile shapes, such as the eccentric cycloid (EC) gearing, enables a high transmission ratio per stage to be achieved, thus reducing the design space required. In order to evaluate the design, a description of the geometry and characteristics of the EC gearing is necessary. The application-optimized design can be made accessible on an interdisciplinary basis using a suitable description language for the product development of the complete robotic system. The paper shows the design and analysis of a planetary gearbox with a high transmission ratio for applications in robotics. The planetary gear stage is designed with the EC gearing, which offers advantages compared to the involute gearing. The performance of the selected gearing is evaluated based on various characteristics. This allows advantages to be identified compared to the established types of transmission for robots and RLS. Overall, the paper presents a new robot gearbox with a comprehensive description and analysis directly accessible for simulation or production using additive manufacturing.

Integrated design and maintenance strategies for wind turbine gearboxes

PurposeThe purpose of this paper is to optimize the maintenance strategies for wind turbine (WT) gearboxes to minimize costs associated with PM actions, cooling, production loss and gearbox replacement. Two approaches, periodic imperfect maintenance and a novel design incorporating alternating gearboxes are compared to identify the most cost-effective solution.Design/methodology/approachThis study employs mathematical modeling to analyze the design, operation and maintenance of WT gearboxes. Two maintenance strategies are investigated, involving periodic imperfect maintenance actions and the incorporation of two similar gearboxes operating alternately. The models determine optimal preventive maintenance (PM) and switching periods to minimize total expected costs over the operating time span.FindingsThe research findings reveal, for the considered case of a moroccan wind farm, that the use of two similar gearboxes operating alternately is more cost-effective than relying on a single gearbox. The mathematical models developed enable the determination and comparison of optimal strategies for various WT gearbox scenarios and associated maintenance costs.Research limitations/implicationsLimitations may arise from simplifications in the mathematical models and assumptions about degradation, temperature monitoring and maintenance effectiveness. Future research could refine the models and incorporate additional factors for a more comprehensive analysis.Practical implicationsPractically, the study provides insights into optimizing WT gearbox maintenance strategies, considering the trade-offs between PM actions, cooling, production loss and gearbox replacement costs. The findings can inform decisions on maintenance planning and design modifications to enhance cost efficiency.Social implicationsWhile the primary focus is on cost optimization, the study indirectly contributes to the broader societal goal of sustainable energy production. Efficient maintenance strategies for WTs help ensure reliable and cost-effective renewable energy, potentially benefiting communities relying on wind power.Originality/valueThis paper introduces two distinct strategies for WT gearbox maintenance, extending beyond traditional periodic maintenance. The incorporation of alternating gearboxes presents a novel design approach. The developed mathematical models offer a valuable tool for determining and comparing optimal strategies tailored to specific WT scenarios and associated maintenance costs.

Dynamic investigation of the electromechanical coupling system in a permanent magnet direct-drive locomotive under rotor eccentricity faults

In the traction system of a direct-drive locomotive, the gearbox design is eliminated, enabling the direct transmission of output torque from the traction motor to the wheelset. Due to this unique structure, rotor eccentricity, which is a common fault in traction motors, can have a direct impact on the dynamic performance of key components such as the motor, bogie, and wheelset in locomotives. In order to investigate the dynamic response of the direct drive locomotive under rotor eccentricity faults, a comprehensive electromechanical coupling model that considers the dynamic motion of the rotor is established in this paper. The coupling effect between the mechanical system and the electrical system, as well as the dynamic forces induced by rotor eccentricity, are taken into account in the model. The simulation results reveal that ripple torque has an obvious effect on rotor dynamics behaviour, while rotor air-gap eccentricity and mass eccentricity exhibit varying degrees of influence on the dynamic performance of the vehicle system. Furthermore, the influence laws of rotor eccentric distance on the vibration responses of critical locomotive components are revealed. These findings provide valuable theoretical guidance for the operational maintenance and fault diagnosis of traction motors in direct-drive locomotives.

Simultaneous Design of Two-stage Gearboxes

Simultaneous Design of Two-stage Gearboxes

Multi-Objective Optimization of a Two-Stage Helical Gearbox Using MARCOS Method

In order to address the Multi-Objective Optimization Problem (MOOP) in building a two-stage helical gearbox, this work presents a novel application of the Multi-Criterion Decision-Making (MCDM) method. The aim of the study is to determine the optimal primary design factors that will increase gearbox efficiency while decreasing gearbox volume. Three main design parameters were chosen for assessment in this work: the first stage’s gear ratio, and the first and second stages’ Coefficients of Wheel Face Width (CWFW). In addition, the MOOP is divided into two phases: phase 1 solves the single-objective optimization problem to reduce the gap between variable levels, and phase 2 solves the MOOP to determine the optimal primary design factors. Furthermore, the Entropy approach was picked to compute the weight criteria, and the MARCOS method was chosen as an MCDM method to handle the multi-objective optimization issue. The following are important characteristics of the study: Firstly, the MCDM method (MARCOS technique) was successfully applied to solve a MOOP for the first time. Secondly, this work has looked into power losses during idle motion to calculate the efficiency of a two-stage helical gearbox. The results of the study were used in the design of a two-stage helical gearbox in order to identify the optimal values for three important design parameters.

Load Carrying Capacity of Case-Carburized Gears with Different Cryogenic Treatments

Abstract Gearboxes of modern drivetrains, e.g., in wind turbines, can be exposed temporarily to low ambient temperatures during their manufacturing or during operation. During manufacturing or assembly, for example, very low temperatures sometimes occur during joining processes due to the cryogenic treatment of the components. In these cases, the temperature depends on the cooling medium used (typically dry ice or liquid nitrogen). Furthermore, depending on the application, gearboxes may be exposed to low ambient temperatures up to -60 °C when used in cold regions. The low temperatures can have an impact on the component properties and thus on the gear load carrying capacity. Therefore, the knowledge of these influences is very important regarding the design and dimensioning of gearboxes. In this publication, further investigations on the load carrying capacity of cryogenic treated gears are presented based on previous research work. The focus is on results on the tooth root and pitting load carrying capacity. The load carrying capacity is analyzed in the context of changes in the component properties as a result of different low temperature treatments, and the dominant influencing factors are identified.

Application of a Multi-Criterion Decision-Making Method for Solving the Multi-Objective Optimization of a Two-Stage Helical Gearbox

This paper provides a novel application of a multi-criterion decision-making (MCDM) method to the multi-objective optimization problem of designing a two-stage helical gearbox. This study’s goal is to identify the ideal primary design elements that increase gearbox efficiency while reducing the gearbox cross-section area. In this work, three primary design parameters were selected for investigation: the gear ratio of the first stage and the coefficients of wheel face width (CWFW) of the first and second stages. The multi-objective optimization problem was further split into two phases: phase 1 solved the single-objective optimization problem of minimizing the gap between the variable levels, and phase 2 solved the multi-objective optimization issue of identifying the ideal key design factors. Moreover, the multi-objective optimization problem was handled by the SAW method as an MCDM approach, and the weight criteria were computed using the entropy approach. This study’s significant characteristics are as follows: First, a multi-objective optimization problem was successfully solved using the MCDM approach (SAW technique) for the first time. Second, the power losses in idle motion were investigated in this work in order to determine the efficiency of a two-stage helical gearbox. From this study’s findings, the ideal values for three major design parameters can be determined for the design of a two-stage helical gearbox.

Additive manufacturing as a resource-saving alternative in the manufacturing process of marine gearbox housing

ABSTRACT Marine gearbox housings are large components of several metres in length and tonnes of weight. The conventional manufacturing process is a time-consuming and elaborate process with the necessity to oversize the components from a load point of view. This results in a redundant amount of energy and resources for manufacturing. In contrast, wire arc additive manufacturing (WAAM) offers the possibility to realize a load- and weight-optimized design and provides an energy- and resource-efficient alternative in the manufacturing of marine gearbox housings. It has been shown that this additive manufacturing process provides the potential of 41% energy reduction and 36% material reduction compared to the iron cast manufacturing process. This is due to the modification of the load flow and the use of the hybrid manufacturing production as well as the possibility to include bionic structures in the gearbox design.

Computing solution spaces for gear box design

AbstractThe design of gear boxes is a complex challenge characterized by conflicting requirements and seemingly circular dependencies. Existing tools support engineers but focus on a single predefined design, often leading to costly iterative processes and non-optimal solutions. Solution Space Engineering (SSE) alleviates this by generating multiple designs represented by solution spaces. For this, a particular model structure is needed, and thus restructuring existing models, e.g., from industry standards. The application of solution spaces to a two-stage gear box is presented.

High Torque and Increased Wear Redefine Gearbox Longevity in Electric Motors

This study explores the accelerated wear of gearboxes driven by electric motors compared to gearboxes in combustion engines, highlighting the important role of lubrication quality. The continuous operation of sugarcane processing machines requires durable gearboxes, especially under the high torque load of electric motors. By analyzing gearbox wear through standard load tests and various lubricant qualities, the findings reveal that superior lubricants significantly reduce wear. These results not only demonstrate the need for customized gearbox designs for electric motors, but also show that improvements in lubrication practices can extend gearbox life and increase efficiency in industrial applications globally. Highlights: Continuous operation vital for production targets. Electric motorbike gearboxes need frequent maintenance. Quality lubrication crucial for gearbox longevity. Keywords: Gearbox, Grind, Sugar Factory

Design and research of the plunger pump mechanism for pumping liquid in reservoir pressure maintenance systems

Nowadays, plunger pumps have the most advanced designs. In fact, plunger pumps are the only ones of their kind, capable of operating at high pressures and have the best characteristics. Their use is growing in industry, as they cope with the harsh conditions of pumping liquids of various types. To maintain reservoir pressure, pumps require a high efficiency and reliable design. In order to ensure the operability of the system, it is necessary to select qualitative indicators according to the criteria of optimality for the design of mechanism parts and to achieve an adequate workflow. Thus, the study and determination of the possibility of improving the performance of plunger pumps remains a current task. The results presented in this article include an analysis of the operating conditions of each of the components of the mechanism using a mathematical model of the drive based on the differential equations of motion of the plunger pump, the determination of the corresponding production processes and the production of finite elements. In addition, a kinematic force analysis of the functions of the mechanism under study (positions of analogues of speeds and accelerations of links) and the found motion characteristics is carried out when solving the problem of dynamics of the main shaft of the machine. This article presents a test report to verify the correct functioning of the mechanism in accordance with the initial parameters of the system, the design of a gear planetary gearbox with cylindrical wheels, a cam mechanism pusher and their type of assembly to be performed. This research is carried out using software for engineering mathematics: Mathcad and Python.

Natural frequency analysis of gear system with interval shaft misalignment in multidimensions

Due to the existing tolerances, the shaft misalignment of gear system is inevitably uncertain and shows interval property, which will cause the natural frequency to fluctuate in an interval range, therefore the traditional dynamics analysis that takes it as a deterministic parameter cannot reflect the interval characteristics of natural frequency. To overcome this conundrum, an improved interval eigenvalue algorithm based on matrix non-negative factorization and the Chebyshev inclusion function was proposed to find the natural frequency range of gear system under such uncertainty. First, the average meshing stiffness range of the gears with interval shaft misalignment is obtained by the Chebyshev interval approach. Then combined with the consideration of the remaining excitation parameter deviation coefficients, the global interval stiffness matrix and mass matrix of a single-stage gear system are obtained. Afterwards, the non-negative factorizations of these two interval matrices are carried out and parameter vertex theory is finally employed to obtain the upper and lower bounds of the eigenvalues. The feasibility of the applied algorithm is verified through comparison with the scanning method. Numerical results show that the uncertainty of shaft misalignment will enormously widen the system's resonance bandwidth and intensify oscillation, these will provide a new and valuable perspective for the tolerance allocation in gearbox design.

Gearbox Design and Improvement for Milling Machines

Gearbox Design and Improvement for Milling Machines

Reliability Optimization Design of Single-Stage Gearbox Based on ANSYS

Reliability Optimization Design of Single-Stage Gearbox Based on ANSYS

Planetary Gearbox Design and Development using Additive Manufacturing

Modern manufacturing technology is dominated by additive manufacturing due to its simplicity, precision, time and material savings, and flexibility in design. The purpose of this study is to propose and print a 3D model of planetary gear trains since these gear trains are more efficient than conventional gear trains and have many advantages. A planet gear trains must have collinear input and output axes in order to achieve compact space requirements. Using even spacing between the planets in a gear train allows both static and dynamic forces to be balanced. It is also possible for multiple planets to produce high torques. Finally, it is capable of providing a wide range of speeds. The printed model performed exceptionally well when it came to performance, and it can be used for both educational and industrial purposes, exhibiting the ability to withstand a high level of stress. The current paper demonstrated the process of 3D printing and the challenges involved in printing planetary gear trains, as well as possible solutions to these challenges. Finally, tolerances were reported as 0.5 mm on the final CAD model, and 0.15 mm on the last updated results.

A model-based approach for gear train whine noise reduction by mesh phasing modification

Heavily loaded gear trains are known to produce a characteristic whine noise and vibration signature, which radiates through the bearings producing an undesired noise emission affecting the NVH behavior of the overall machine. This phenomenon is generated by the variable mesh stiffness and the static transmission error of the gear pairs in mesh within the gear train, but its magnitude strongly depends on how the meshing processes combine between each others. In this context, the present work proposes an analytical methodology to predict amplitude and direction of the variable loads applied on the bearings of idle gears, assuming quasi-static conditions. The dissertation demonstrates that the multiple mesh forces produce a variable load on idle gear bearings describing an ellipse whose shape depends on various geometrical parameters of the system. Numerical examples are shown to assess the potentials of the method and highlight how gear train spatial layout and phasing between different meshings may be used during gearbox design projects to limit the emitted noise of the gear train.

Design, Simulation and Multi-Objective Optimization of a Micro-Scale Gearbox for a Novel Rotary Peristaltic Pump.

Peristaltic pumps are widely used in biomedical applications to ensure the safe flow of sterile or medical fluids. They are commonly employed for drug injections, IV fluids, and blood separation (apheresis). These pumps operate through a progressive contraction or expansion along a flexible tube, enabling fluid flow. They are also utilized in industrial applications for sanitary fluid transport, corrosive fluid handling, and novel pharmacological delivery systems. This research provides valuable insights into the selection and optimal design of the powertrain stages for peristaltic pumps implemented in drug delivery systems. The focus of this paper lies in the simulation and optimization of the performance of a power transmission gearbox by examining the energy consumption, sound levels, reliability, and volume as output metrics. The components of the powertrain consist of a helical gear pair for the first stage, a bevel gear pair for the second one, and finally a planetary transmission. Through extensive simulations, the model exhibits promising results, achieving an efficiency of up to 90%. Furthermore, alternative configurations were investigated to optimize the overall performance of the powertrain. This process has been simulated by employing the KISSsoft/KISSsys software package. The findings of this investigation contribute to advancements in the field of biomedical engineering and hold significant potential for improving the efficiency, reliability, and performance of drug delivery mechanisms.

A multi-objective optimization design approach of large mining planetary gear reducer

A two-stage computational framework is proposed to optimize the radiated noise and weight of a large mining planetary gear reducer under the rated conditions, based on a combination of response surface methodology and multi-objective optimization. The well-established transient dynamic analysis model of a large mining planetary gear reducer, which is used to analyze the mechanical strength and acoustic characteristics of the gear reducer. A unified experimental design is developed to obtain the response surface of the gearbox radiated noise and the mass of the gearbox housing. After obtaining the multi-objective optimization function, the multi-objective optimization problem for a lightweight and low-noise gearbox is performed using non-dominated sorting from the Genetic Algorithm II (NSGA-II). The research results demonstrates the effectiveness of the proposed optimization method in reducing vibrating amplitude and weight of the gearbox. This is crucial for minimizing energy consumption and enhancing the overall performance of the system. Additionally, the optimized gearbox design not only saves energy but also contributes to the reduction of carbon emissions, making it environmentally friendly.

Optimization of planetary gearbox using nature inspired meta-heuristic optimizers

In this study, a detailed research was carried out to solve the two-stage planetary gearbox design optimization problem by using nature-inspired optimization methods. Seven different nature-inspired meta-heuristic optimizers were applied to minimize the volume of the planetary gear. The recent optimizers, Grey Wolf Optimizer, Artificial Bee Colony, Multi-verse Optimizer, Cuckoo Search, Whale Optimization Algorithm and Salp Swarm Algorithm methods were applied to the problem for the first time. The optimal volume values obtained with the seven different optimizers are much better than the best values known in the literature. The best fitness value obtained is 30% better than the best known in the literature.

Evaluation of friction calculation methods for rolling bearings

In gearboxes, rolling bearing power losses often make up a large amount of the total gearbox power losses. Therefore, an exact calculation of rolling bearing power losses is very important for resource and energy efficient gearbox design. The state of the art offers numerous friction calculation methods with different levels of detail to calculate power losses of rolling bearings. Bearing manufacturers like SKF and Schaeffler offer popular bearing-based/global calculation methods for standard rolling bearings. Contact-based/local calculation methods can consider a wider application field by generalization of tribological relations, which enables its application to e.g. hybrid bearings or non-standard bearings. The different methods may yield widely differing results. For its validation, measurement results are required. In this study, a broad comparison of calculation results with substantial measurement results is shown. Based on the validation a classification of the calculation methods is derived, which provides guidance for the design engineer to choose the appropriate method for the respective application. Contact-based/local calculation methods have the potential to predict friction in rolling bearings precisely.