scholarly journals Properties of Elasto-Hydrodynamic Oil Film in Meshing of Harmonic Drive Gears

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1194
Author(s):  
Adam Kalina ◽  
Aleksander Mazurkow ◽  
Waldemar Witkowski ◽  
Bartłomiej Wierzba ◽  
Mariusz Oleksy
Keyword(s):  
Theoretical Models ◽  
Tooth Profile ◽  
Wave Transmission ◽  
Harmonic Drive ◽  
Static Characteristics ◽  
Strain Wave ◽  
Correct Operation ◽  
Structural Problem ◽  
Oil Film

Among the essential issues facing designers of strain wave gears, the provision for correct lubrication should be of paramount importance. The present paper presents the results of research on elasto-hydrodynamic oil film in meshing of a harmonic drive with an involute tooth profile. The research was carried out based on theoretical models developed by Dowson and Higginson. For the discussed structural problem, results of the study are presented graphically in the form of static characteristics of the oil film. Correct operation regimes were determined for two different oils. The paper also provides a review of information concerning the design and principle of operation of strain wave transmission.

On a Gearing Problem in Conventional Harmonic Drives With Involute Toothed Gear Set

2011 ◽  
Author(s):  
Bikash Routh ◽  
Rathindranath Maiti
Keyword(s):  
Applied Load ◽  
Harmonic Drive ◽  
Strain Wave ◽  
Base Circle ◽  
Pitch Curve

Circular pitches of flex spline teeth of a ‘Strain Wave Gearing’, also known as a ‘Harmonic Drive’, are deformed when the Strain Wave Generating Cam is inserted into the flex spline cup. In the present work the deformed pitch distances considering that flex spline teeth remain rigid while the rim deforms, are estimated. No applied load is considered. It is also shown that if the cam is elliptical then the pitch curve is not an ellipse and vice versa. Geometries of such curves can be defined following the analysis presented in this paper. Cases of both undeformed flex spline with circular spline and deformed flex spline with circular spline, with involute teeth, are considered to find out tooth positions. Geometries of involute teeth profiles in mesh are examined and compared considering oval shaped (on deformation) base drum of flex spline where as base circle of circular spline remained circular.

Evidence of secondary tooth contact in harmonic drive, with involute toothed gear pair, through experimental and finite element analyses of stresses in flex-gear cup

2016 ◽  
Vol 232 (2) ◽  
pp. 341-357 ◽  
Author(s):  
Vineet Sahoo ◽  
Rathindranath Maiti
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Major Axis ◽  
Initial Stresses ◽  
Gear Pair ◽  
Ring Gear ◽  
Harmonic Drive ◽  
Strain Wave ◽  
Element Analysis ◽  
Full Load

Stresses in flex spline/gear cup in harmonic drives with involute toothed gear pair and conventional strain wave generating cam are analyzed using finite element method in ANSYS® environment and experiments. The most innovative part of this investigation is establishing the evidence of secondary contacts and probable load shared by those contacts experimentally over the finite element analysis. Aiming at the performance improvement of gearing in harmonic drives, with involute toothed gear pair, the investigations are carried out through the following analyses. (a) Initial stresses in flex gear cup due to cam insertion only. (b) Stresses in flex gear cup at no load in fully assembled harmonic drive components i.e. flex gear, ring gear, and strain wave generating cam. (c) Stresses in flex gear cup at full load passing through the two pitch points, i.e. the intersection points of ring gear pitch circle, flex gear pitch curve, and major axis on both sides. Finally, (d) stresses in flex gear cup at full load distributed over all possible primary and secondary contacts, in proportion to their contact intensities. Recorded strains of the flex-gear cup while the cam being rotated showed very good agreement with the results obtained by finite element analysis with proper modeling of loading.

Effect of tooth waist order parameters of double involute gears on lubrication performance of gear drive

2016 ◽  
Vol 68 (6) ◽  
pp. 671-675 ◽  
Author(s):  
Zhimin Fan ◽  
Wanfeng Zhou ◽  
Ruixue Wang ◽  
Na Wang
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Reference Value ◽  
Tooth Profile ◽  
Order Parameters ◽  
Content Type ◽  
Oil Film ◽  
Gear Drive ◽  
Involute Gear ◽  
Lubrication Performance ◽  
Involute Gears

Purpose The purpose of this paper is to derive a new lubrication model of double involute gears drive and study the effect of the tooth waist order parameters of double involute gears on lubrication performance. Design/methodology/approach The new lubrication model of double involute gears drive was established according to the meshing characteristics of double involute gears drive and the finite length line contact elastohydrodynamic lubrication theory. Numerical calculation of the lubrication model of gear drive was conducted using the multigrid method. Findings The results show that the oil film necking phenomenon and the oil film pressure peak emerged at the tooth waist order area and the tooth profile ends, and when compared with involute gear, the lubrication performance at the tooth waist order area is better than that at the tooth profile ends. The effect of tooth waist order parameters on lubrication performance at the tooth waist order area was greater than that at other areas. Originality/value This research will promote the application of the double involute gear as soon as possible, and it has the reference value for other types of gears.

STATIC CHARACTERISTICS OF OFFSET 8-LOBE JOURNAL BEARINGS

Tribologia ◽  
2021 ◽  
Vol 295 (1) ◽  
pp. 39-51
Author(s):  
Stanisław Strzelecki
Keyword(s):  
Laminar Flow ◽  
Equilibrium Position ◽  
Iterative Procedure ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
Static Characteristics ◽  
Oil Film ◽  
Cooling Conditions ◽  
Grinding Machines

The 8-lobe journal bearings have found application in the bearing systems of spindles of grinding machines. The design of bearings and the large number of lobes and oil grooves assures good cooling conditions of bearing. These bearings can be manufactured as the bearings with cylindrical, non-continuous operating surfaces separated by six lubricating grooves, bearings with the pericycloidal shape of the bearing bore, and as offset journal bearing. This paper presents the results of the computation of static characteristics of an offset 8-lobe journal bearing operating under the conditions of an aligned axis of journal and bush, adiabatic oil film, and at the static equilibrium position of journal. Different values of bearing length to diameter ratio, relative clearance, and lobe relative clearance were assumed. Reynolds' energy and viscosity equations were solved by means of an iterative procedure. Adiabatic oil film, laminar flow in the bearing gap, and aligned orientation of journal in the bearing were considered.

scholarly journals Low-Cost, Continuously Variable, Strain Wave Transmission Using Gecko-Inspired Adhesives

2019 ◽  
Vol 4 (2) ◽  
pp. 894-901 ◽  
Author(s):  
Nicholas D. Naclerio ◽  
Capella F. Kerst ◽  
David A. Haggerty ◽  
Srinivasan A. Suresh ◽  
Sonali Singh ◽  
...  
Keyword(s):  
Low Cost ◽  
Wave Transmission ◽  
Strain Wave

Design and development of strain wave generating cam for a new concept ‘harmonic drive’

2012 ◽  
Vol 227 (8) ◽  
pp. 1870-1884 ◽  
Author(s):  
Rathindranath Maiti ◽  
Indraneel Biswas ◽  
Vivek Nema ◽  
Saurabh Basu ◽  
Bhabani Sankar Mahanto ◽  
...  
Keyword(s):  
Harmonic Drive ◽  
Strain Wave ◽  
Assembly Method ◽  
Circular Arcs ◽  
Single Piece ◽  
Cam Profile ◽  
Active Zones ◽  
Gear Contact ◽  
Inner Race ◽  
Center Distance

A split cam design is proposed to solve the problem of assembly of the single piece cam in the flexible raced bearing of an earlier proposed novel harmonic drive system, which shows better torque characteristics and capacities in comparison to the conventional one of same size with oval-shaped strain wave generating cam. The cam profile has circular arcs at two working zones at 180° phases. The proposed profile shape is identified as the cause of trouble in assembly if the cam is made single piece. The split cam is made of two identical pieces having circular arc edges. These pieces constitute the cam in assembly after putting it inside the inner race of the flex bearing and adjusted by an adjuster. The design, kinematics, and the assembly method of the proposed split cam are presented in this article. The split cam arrangement not only solves the assembly problem but also gives a scope of fine adjustment of center distance (eccentricity). Such an adjustment is not possible in conventional oval wave generating cam. Stresses in flex gear cups assembled with both type cams at load and no-load conditions are estimated using finite element method. Some results are verified experimentally. Although the flex gear cup with the proposed split cam experiences lower stresses at load transmitting active gear contact zones, it shows higher stresses at some non-active zones (where teeth are free of load). It is apparent from results that stresses at those non-active zones do not increase substantially with the increase in torque, as they are away from active zones.

scholarly journals Water wave transmission by an array of floating discs

2015 ◽  
Vol 471 (2173) ◽  
pp. 20140698 ◽  
Author(s):  
L. G. Bennetts ◽  
T. D. Williams
Keyword(s):  
Wave Energy ◽  
Water Wave ◽  
Theoretical Models ◽  
Wave Transmission ◽  
High Concentration ◽  
Low Concentration ◽  
Wave Basin ◽  
Model Predictions ◽  
Rigid Body Motions ◽  
Incident Wave Energy

An experimental validation of theoretical models of regular-water-wave transmission through arrays of floating discs is presented. The experiments were conducted in a wave basin. The models are based on combined potential-flow and thin-plate theories, and the assumption of linear motions. A low-concentration array, in which discs are separated by approximately a disc diameter in equilibrium, and a high-concentration array, in which adjacent discs are almost touching in equilibrium, were used for the experiments. The proportion of incident-wave energy transmitted by the discs is presented as a function of wave period, and for different wave amplitudes. Results indicate the models predict wave-energy transmission accurately for small-amplitude waves and low-concentration arrays. Discrepancies for large-amplitude waves and high-concentration arrays are attributed to wave overwash of the discs and collisions between discs. Validation of model predictions of a solitary disc's rigid-body motions are also presented.

Static Characteristics of the Regular and Reversible Rotation Type Herringbone Grooved Journal Bearing

1989 ◽  
Vol 111 (3) ◽  
pp. 484-490 ◽  
Author(s):  
Nobuyoshi Kawabata ◽  
Yasumi Ozawa ◽  
Shuji Kamaya ◽  
Yutaka Miyake
Keyword(s):  
Numerical Analysis ◽  
Journal Bearing ◽  
Load Capacity ◽  
Maximum Load ◽  
Radial Load ◽  
Static Characteristics ◽  
Oil Film ◽  
New Type ◽  
Load Component ◽  
Reversible Rotation

A new type herringbone grooved journal bearing, which produces an oil film bearing pressure with a shaft or bearing rotation in either direction, is proposed in this paper. A numerical analysis of the bearing parameters using the narrow groove theory and the Gu¨mbel condition confirmed that the load capacity of this bearing and the radial load component (related to stability) do not differ greatly from those of a conventional bearing. The values of the bearing parameters which give maximum load capacity, and the values of the load capacity and its direction angle are also determined numerically for the case of either grooved member or smooth member rotation.

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