Ring Gear Research Articles

A numerical model for vacuum carburization of an automotive gear ring

A vacuum carburizing-heat treatment of an annulus gear ring is simulated via a carburized predictive finite element model that accounts for both heat transfer and carbon diffusion. Profiles of carbon concentration along the depth of the gear ring were calculated and are congruent with measured values, which were obtained by a glow discharge spectrometer (GDS). While sensitive to carbon content, rigorous observation of the microstructures in the gear ring after heat treatment was attempted by transmission electron microscopy (TEM). The finial various martensitic microstructures in several parts of the gear ring may be well explained on the basis of the calculated carbon concentration.

Development of a Variable-Inertia Device With a Magnetic Planetary Gearbox

This paper presents a mechanical device with controllable inertia, in which a magnetic planetary gearbox (PG) is employed to hold two free terminals (the carrier and sun gear) and one feedforward control terminal (the ring gear). Based on the concept of inerter design and impedance control, the ring-gear motor controls the equivalent inertia of the carrier. The sealless nature of the proposed noncontact magnetic PG provides a low-inertia design ability and an over-load protection characteristic for a high-torque transmission. The control block diagram technique is utilized to represent the dynamic model of the variable-inertia device for the equivalent-inertia derivation and computer simulation, in which its equivalent inertia can be found by the transfer function from the torque to the acceleration at the carrier. Finally, the dynamic model is verified by experiments, and the controlled range of the equivalent inertia is illustrated.

The Computer Solidification Simulation and Process Optimization of Gear Ring

The numerical solidification simulation for gear ring steel casting has been made, and the location and reasons forming casting defects have been predicted by HUAZHU CAE software. Simulating result shows that the directional solidification and efficient feeding were maintained and the casting perfects can be realized by means of the computer simulation optimizing technological and rationally design of gating system, insulated risers, iron chill and compensating efficiently. After magnetic particle detection and ultrasonic inspection, the properties and microstructure of the Gear ring steel casting are in accord with the international standard.

Laser welding of cast iron and carburized steel for differential gear

This study concerned laser welding replacing the traditional bolted connection of the ring gear and differential case in the power train of the automobile. Laser welding is necessary to reduce weight and manufacturing cost, since the bolted connection method requires additional parts and space. In the differential gear, however, it is difficult to control the welding processes because cast iron and carburized steel contain high carbon content. To solve these welding problems, laser welding using Ni-base filler metal was used in this work. The results of welding with Ni-base filler metal satisfied the torsional stiffness and durability, but compared to the bolted connection method, noise and hardness problems occurred. Therefore, to solve these problems, penetration depth was decrease from 5mm to 4mm and the carburized layer of the ring gear was cut with 1mm. As well, numerical method was used to evaluate welding deformation, torsional stiffness and fatigue.

Mechanism Design for a Dual Cycloid Reducer

In this paper, we considered a dual cycloid reducer(DCR) which consists of a planet gear with shortened epitrochoid and its conjugate ring gear. The geometric relations between a meshing gear pair were investigated to find the conjugate ring gear profile. It reveals that the three design parameters including the pin radii, the eccentricities, and the trochoid ratios should be identical to each other between meshing gears. Through the computer simulation for two examples, the proposed meshing conditions for the DCR are verified successfully.

Numerical Simulation and Technology Research on the Precision Forging for Inner Ring Gear

Rigid-viscoplastic finite element method was used to analysis the cold extrusion of the external boss and ring gear. Some groups of numerical models were built with different design parameters of die, geometric parameters of gear, processing conditions, and the service loads were investigated. Form the investigation; we predicted the forming defects occurring in the practice. Based on Archard model the lives of dies were predicted. The conclusion above has more guidance to the production.

A Discrete Lumped-Parameter Dynamic Model for a Planetary Gear Set with Flexible Ring Gear

A discrete lumped-parameter model for a general planetary gear set is proposed, which models the continuous flexible ring gear as discrete rigid ring gear segments connected with each other through virtual springs. The ring-planet mesh is analyzed to derive equations of motion of ring segments and planet. By assembling equations of motion of each individual component, the governing equations of planetary gear system are obtained. The solution for eigenvalue problem yields to natural frequencies and corresponding vibration modes. The simulations of example system reveal that the ring gear flexibility decreases system lower natural frequencies and the vibration modes can be classified into rotational, translational, planet and ring modes.

Analysis on Deformation and Relieving of Spline in 1.5MW Wind Turbine Gearbox

For the sun gear shaft in wind turbine gearbox, the deformation will occur on the inner spline because of the thermal inserting of ring gear. So, the spline pair should be tooth relieved to avoid decrease of backlash and conflict of copulate parts. Based on the finite element analysis results, the deformation caused by the thermal inserting on the inner spline was calculated, and the theoretical tooth relieving curve was got. The practical thermal inserting deformation on the spline was measured. And the results indicate that the measuring deformations are in good consistency with the deformation calculated by finite element analysis method. The spline deformation and tooth relieving calculation method can provide a reference for the tooth relieving of the spline on long structure sun gear shaft in 1.5MW wind turbine gearbox.

Analysis of power flow in a counter-rotating epicyclic gearing for electrical propulsion system

A novel compound epicyclic gearing that combines a planetary gear train with a differential gear train is designed for an electrical propulsion system of underwater unmanned vehicles. This epicyclic gearing can transform a single input into two counter-rotating outputs with equal torque amplitudes and speeds. Based on the analysis method of power flow in the differential gear train, the character of the power flow of the compound epicyclic gearing was determined. After comparing with the power distribution of input flow, the condition of this mechanism without power recirculation was investigated. Because the reactive torque of the motor stator is balanced by the torque on ring gear of planetary gear train, no net torque acts on the vessel being propelled.

Study on the Micro Thermal EHL Behavior of Wind Turbine Gearbox

A complete numerical solution for the micro thermal elastohydrodynamic lubrication (EHL) of planetary gearing in wind turbine gearbox is obtained with taking roughness effects and characteristics of non-Newtonian fluids into account. The oil film pressure profile, film shape and the trend of equivalent temperature rise in planetary gearing in special meshing points are drawn. Through comparing with lubrication performance in different surface morphology between Ra=0.8μm and 0.2μm, the results show that the film thickness ratio of ring gear and planetary gears with Ra=0.8μm is greatly smaller than 1.5. From the relationship between tooth surface damage and film thickness ratio, these gears are in abnormal lubrication state, surface damage, when Ra=0.8μm, can theoretically reach more than 15%. However, the surface damage ratio with Ra=0.2μm has been greatly deceased, so as to that it provides a theoretical basis of reliable lubrication analysis for wind turbine gearbox.

Analysis on Transient Stress State of Elastic Thin-Wall Component of Harmonic Gear Drive

To overcome the crack problem of thin wall structure of harmonic gear transmission─ flexspline, we develop a transient dynamic analysis model for B1-50-80 harmonic gear transmission. Based on large displacement and large strain theory, the transient stress state of the flexspline is analyzed under maximum rated conditions. The distribution law of transient stress is obtained when the amplitude of stress histories on flexspline gear changes in sine form and the change process of stress of flexspline gear ring are from top to bottom. We observe that over-stress of flexspline on tube gradually decreases along the axis and the stress distribution between flexspline and flexspline gear ring becomes a certain slant due to force irregularly on flexspline tooth in the axial direction. The maximum Von Mises stresses appears in the contact regions between flexspline gear ring and wave generator. Therefore, cracks will originate from the dedendum regions of flexspline, then extend along the axis, and finally expand along 45°.

Study on the Rules and Effects of Wear on Die Service Life in Steel Synchronizer Gear Ring Forging Process

The die accuracy and die service life reduce due to die wear during precision forming processes of steel synchronizer gear ring. The most serious part of wear is the middle between two tooth shapes. The rules of the wear and initial die hardness and frictional coefficient are analyzed based on numerical simulation. It shows that the higher of the initial die hardness, the better antiwear and good lubrication is benefit to reduce wear and prolong the die service life. The effect of the temperature on die life is reflected through hardness. The relationship of die hardness and die temperature, forming time is deduced. The higher of the die temperature and the longer of the forging time, the more serious of die wear. To prolong the die life and improve the quality of forgings, the synthetic forming technology is adopted and the ejection way and control system of the Plate Friction Press are improved. Experiment verification shows that the die service life has been prolonged.

Effect of mesh phase on wave vibration of spur planetary ring gear

Abstract The distinctive wave vibration of a ring gear affected by mesh effect is investigated based on the inherent symmetry of spur planetary gears. Compared to prior analysis, this work mainly examines the forced flexural and extensional vibrations. The superposition principle and the Fourier series are introduced to jointly deal with the wave vibrations. The dynamics of the ring gear shows that the effect of the mesh phase on the wave vibration is mainly embodied by the specific relationships between the tooth number, the planet number, the largest common factor of them, the planets’ circumferential position, and the excited wave numbers in the typical rotational, translational and planet modes. For the equal systems, the three modes can be possibly excited depending on the specific mesh phase. And the dominant vibration orders of them are 0, 1 and 2, respectively. The non-zero lowest order is equal to the largest common factor of the two numbers. But for the diametrical ones, only the first two modes can be excited, and the dominant orders of them are 0 and 1, respectively. And the lowest non-zero wave number is 2 for even tooth number and 1 for odd tooth number. As a typical application, these relationships can be used to predict and suppress some potential wave resonances of the ring gear by optimizing the ring-planet mesh phase. The main results are demonstrated with finite element examples and comparisons with the existing literature.

The Instantaneous Efficiency of Epicyclic Gears in Flight Control Systems

The instantaneous efficiency of an epicyclic gear rotary actuator is an important factor in sizing flight control systems where compound epicyclic gear trains are typically used. The efficiency variation can be smooth or fluctuating depending on the combination and timing of the teeth of ring, planet, and sun gears. In this paper, the instantaneous efficiency characteristics of synchronous and nonsynchronous actuators under forward-driving with opposing load and reverse-driving with aiding load are investigated. The emphasis will be on instantaneous, rather than average efficiency of gears. Several gear arrangements are considered: external and internal gears, simple planetary gears and compound planetary gears. Efficiency will be discussed considering not only the geometry of the mating gears, but also the relative phasing of the planet gears relative to the sun and ring gears. Synchronous compound epicyclic gears are shown to have large fluctuation in their instantaneous efficiency. When reverse-driving efficiency falls below 0%, the unit cannot be back-driven and will chatter. Nonsynchronous compound gears have a smaller variation in instantaneous efficiency. However, extra care must be taken in timing the compound planet gears, as well as clocking position of compound planet gears relative to ring gears and the sun gear.

Multiphysics Modeling of Induction Hardening of Ring Gears for the Aerospace Industry

Induction heating has been widely used for heat treating and especially surface hardening in a broad variety of applications, ranging from the automotive to the renewable energy market. However, the lack of precise knowledge about the interrelation between all the concurrent physical phenomena occurring within the part during the heating cycle has restricted its use to mass-production items (mostly gears). The benefits of this technology, which is clean, repeatable, and cost-effective, could boost its introduction into more conservative industry sectors, such as aerospace, where furnace-based treatments (e.g., carburizing) represent the golden standard. The major limitation is related to the optimization of the induction hardening process, which usually requires significant material know-how and can thus be very long and expensive. Computer simulation could provide a general tool for understanding and improving the critical aspects of each step of the process, thus speeding up the spreading of the induction technology into new markets.

Tool Load during Multi-Flank Chip Formation

Tools used in cutting processes with multi-flank chip formation like gear hobbing or bevel gear cutting, often reach their tool life due to excessive wear at the tool corner radius. Tool wear depends on the strength of the cutting edge and on the thermal and mechanical load. The objective of this work is to analyze the thermal and mechanical tool load during multi-flank chip formation. As the tool load cannot be measured in the necessary high local resolution, a finite element based machining simulation is used to model the process of chip formation. The simulation is able to calculate the temperature and stress distribution along the cutting edge. For the examinations presented in this report the bevel gear cutting process for ring gears is simulated. The simulation results show a significant thermal and mechanical load maximum at the tool corner, where the maximal wear occurs in cutting.

Elastohydrodynamic Lubrication Design of Planetary Gear Transmission

Based on elastic hydrodynamic lubrication (EHL) theory, an EHL model of the meshing between the sun gear and planet gear in planetary gear transmission was established. The EHL oil film thicknesses at meshing areas and those distributions for two operation cases were calculated: one case with the sun gear as the driving gear and another case with the ring gear as the driving gear. The Lubrication with second case was worse. Through the many comparing calculations the lubrication film thickness can be significantly increased by right parameter design. Reasonable raise of lubricant viscosity can get better gear lubrication. Increased gear pressure angle can greatly increase the oil film thickness. The increase of oil film thickness can improve the lubrication of gears and prevent wearing and reduce the production cost of gears, which have great practical value.

The Structure Design of Electromagnetic Clutch in the Adverse Circumstances

The trajectory control tool of high build-up rate well-bore, is such a kind of down hole tool that is used to control the well-bore trajectory of the extended reach well. Due to the complex working environment, so it is necessary to design a special electromagnetic clutch. Firstly we should analysis the hostile working environment of the special electromagnetic clutch. The slipping toothed electromagnetic clutch is selected and structural design is going on to adapt the hostile working environment. In order to meet requirements of meshing when the axis is turning, armature ring gear has been designed specially. The reliability of the design also has been checked and it is proved that such kind of design can meet requirements of working under the hostile environment.

System And Method For Monitoring The Condition Of A Gear Assembly

A system and method for monitoring the condition of a gear assembly analyzes a signal output by a vibration detector that is attached to the gear assembly. Each time that an amplitude of the signal output from the vibration detector exceeds a threshold value, the system assumes that a debris particle has passed between meshing parts of the gear assembly. The number of times that this occurs, and possibly the amplitude of the vibrations are analyzed to determine a condition of the gear assembly, and possibly a damage index. This system and method are particularly applicable to planetary gear arrangements where the vibration detector can be mounted on a fixed ring gear of the gear assembly, or a structure upon which the fixed ring gear is mounted.

Calculation Method for the Profile Curves of Cycloidal Pump

The calculation method for profile curves in a kind of cycloidal pump was proposed based on meshing principle. According to the relative motion of the rotors and coordinate transformation method, the profile coordinates of cycloidal gear were obtained. The profile coordinates of cylindrical ring gear were accurately calculated in accordance with the meshing region and the non-meshing region. The example of design and calculation was also given in this paper. According to the results, the profile curve of rotors was drawn.