A Wave Generator of New Concept for Flex Gear of Harmonic Drive With Pure Involute Tooth Gear Pairs

2000 ◽  
Author(s):  
R. Maiti ◽  
A. K. Roy
Keyword(s):  
New Wave ◽  
Harmonic Drive ◽  
Tooth Gear ◽  
Circular Arcs ◽  
Wave Generator ◽  
Accurate Performance ◽  
Involute Gears ◽  
Cam Profile ◽  
Engagement And Disengagement ◽  
Made In

Abstract A new wave generator (or cam) is proposed (Maiti, Patent 1995) to drive the flex gear of strain wave gearing i.e., harmonic drives with gear pairs of pure involute profiles. The cam profile is made of circular arcs at the two contact zones and shifted elliptical curves for the other zones. The geometric constniction is made in such a way that tip interference is properly avoided for both engagement and disengagement with nominally stubbed or full depth involute gears. The theories are established to verify other geometric and gearing conditions. Evidently, in the existing products (all are patented design) the profiles are non-involute and none of them offers ideal gear kinematics. It is expected that this new harmonic drive will offer the best gearing kinematics and will have desired accurate performance.

A Novel Harmonic Drive With Pure Involute Tooth Gear Pair

2004 ◽  
Vol 126 (1) ◽  
pp. 178-182 ◽  
Author(s):  
Rathindranath Maiti
Keyword(s):  
New Wave ◽  
Harmonic Drive ◽  
Tooth Gear ◽  
Circular Arcs ◽  
Wave Generator ◽  
Involute Gears ◽  
Cam Profile ◽  
Pitch Curve ◽  
Engagement And Disengagement ◽  
Circular Pitch

Consider commercially available “harmonic drives” or “strain wave gearings” (all patented designs). The tooth profiles of the mating pairs of teeth of the noncircular (pitch curve) flex gear and circular (pitch circle) ring gears are nearly conjugate and noninvolute. Evidently none of them offers ideal gear kinematics. In this paper, we propose a new wave generator (or cam) to drive flex gears of harmonic drives with fully conjugate gear pairs of purely involute profiles. The cam profile is made of circular arcs at the two diametrically opposite contact zones and shifted elliptical curves for the other two zones. The geometric construction is done in such a way that tip interference is properly avoided for both engagement and disengagement with nominally stubbed or full depth tooth involute gears. We develop the theory of geometric and gearing conditions. We have also built a physical model in order to verify the geometry of tooth interference and other relevant gearing kinematics.

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 Loop-Type Wave-Generation Method for Generating Wind Waves under Long-Fetch Conditions

2017 ◽  
Vol 34 (10) ◽  
pp. 2129-2139 ◽  
Author(s):  
Naohisa Takagaki ◽  
Satoru Komori ◽  
Mizuki Ishida ◽  
Koji Iwano ◽  
Ryoichi Kurose ◽  
...  
Keyword(s):  
Wind Wave ◽  
Wind Waves ◽  
Peak Frequency ◽  
Wave Generation ◽  
New Wave ◽  
Wave Tank ◽  
Irregular Wave ◽  
Wind Speeds ◽  
Type Wave ◽  
Wave Generator

AbstractIt is important to develop a wave-generation method for extending the fetch in laboratory experiments, because previous laboratory studies were limited to the fetch shorter than several dozen meters. A new wave-generation method is proposed for generating wind waves under long-fetch conditions in a wind-wave tank, using a programmable irregular-wave generator. This new method is named a loop-type wave-generation method (LTWGM), because the waves with wave characteristics close to the wind waves measured at the end of the tank are reproduced at the entrance of the tank by the programmable irregular-wave generator and the mechanical wave generation is repeated at the entrance in order to increase the fetch. Water-level fluctuation is measured at both normal and extremely high wind speeds using resistance-type wave gauges. The results show that, at both wind speeds, LTWGM can produce wind waves with long fetches exceeding the length of the wind-wave tank. It is observed that the spectrum of wind waves with a long fetch reproduced by a wave generator is consistent with that of pure wind-driven waves without a wave generator. The fetch laws between the significant wave height and the peak frequency are also confirmed for the wind waves under long-fetch conditions. This implies that the ideal wind waves under long-fetch conditions can be reproduced using LTWGM with the programmable irregular-wave generator.

scholarly journals Made in Yugoslavia: Studies in Popular Music

2021 ◽  
Vol 57 (1) ◽  
pp. 271-282
Author(s):  
Laura Emmery
Keyword(s):  
World War Ii ◽  
Popular Music ◽  
Eastern Europe ◽  
New Wave ◽  
World War ◽  
The West ◽  
The Balkans ◽  
History Of ◽  
Comprehensive Discussion ◽  
Made In

Made in Yugoslavia: Studies in Popular Music (edited by Danijela Špirić Beard and Ljerka Rasmussen) is a fascinating study of how popular music developed in post-World War II Yugoslavia, eventually reaching both unsurpassable popularity in the Balkans and Eastern Europe, and critical acclaim in the West. Through the comprehensive discussion of all popular music trends in Yugoslavia − commercial pop (zabavna-pop), rock, punk, new wave, disco, folk (narodna), and neofolk (novokomponovana) − across all six socialist Yugoslav republics, the reader is given the engrossing socio-cultural and political history of the country, providing the audience with a much-needed and riveting context for understanding the formation and the eventual demise of Tito’s Yugoslavia.

Loaded Tooth Contact Pattern Analysis for Strain Wave Gear With Non-Elliptical Wave Generator

2019 ◽  
Author(s):  
Zhiyuan Yu
Keyword(s):  
Finite Element ◽  
Pattern Analysis ◽  
Element Model ◽  
Tooth Surface ◽  
New Wave ◽  
Contact Pattern ◽  
Strain Wave ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Wave Generator

Abstract This paper presents a new non-elliptical wave generator for strain wave gear to improve its contact pattern quality. The new wave generator has a polynomial profile at one cross section, then crowned along the lead direction. The lead crowning uses a parabolic function with crowning amount controlled by parabolic coefficient. Loaded tooth contact pattern analysis based on finite element method is used to evaluate the new design. The result shows that the new design will avoid the edge contact between wave generator and flexspline, which reduces contact pressure and improve the wearing life of the gear. It also improves the contact pattern quality of the tooth surface. Comparing with elliptical wave generator, the new wave generator with polynomial profile and lead parabolic crowned surface offers more design freedom to improve strain wave gear’s performance. The parametric equation of the new wave generator is defined intuitively, and it can be easily adapted for any type of strain wave gear. Furthermore, the finite element model for the strain wave gear is a new development and application for Loaded Tooth Contact Analysis (LTCA).

Deformation of Flexspline under Transmission Force in Harmonic Drive

2010 ◽  
Vol 97-101 ◽  
pp. 3536-3539 ◽  
Author(s):  
Xiao Xia Chen ◽  
Shu Zhong Lin ◽  
Jing Zhong Xing
Keyword(s):  
Elastic Deformation ◽  
Shell Element ◽  
Beam Element ◽  
Tangential Displacement ◽  
Harmonic Drive ◽  
Ansys Software ◽  
Neutral Layer ◽  
Experimental Distribution ◽  
Wave Generator ◽  
Tangential Forces

Method to investigate the elastic deformation of a flexspline in harmonic driver was developed under assembly force from wave generator and transmission force. Shell element and tapered beam element were applied to model the flexspline cone and the teeth on the flexspline respectively. Forced displacement of the flexspline in assembly state was imposed by contact analysis between the flexspline and wave generator. According to experimental distribution of tangential forces in transmission state, applying forces at the teeth tips on the flexspline in mesh state, deformation distribution under transmission torque loading was obtained. Simulations of assembly state and transmission state were realized in ANSYS software. In three sections of tooth ring vertical to the axis, the deformation distributions of the flexspline under specified displacement in assembly state were compared with the theory results. Deformation between tip of tooth and neutral layer in assembly state and in transmission state were compared respectively. The deformation results agreed well with the theory results in assembly state, while difference was found in tangential displacement on tooth tips in transmission state, which may influence mesh property evidently under transmission loading.

scholarly journals Study on Lubrication Characteristics of Novel Forced Wave Generator of Harmonic Drive without Flexible Bearing

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 215
Author(s):  
Hongli Jia ◽  
Hongbing Xin
Keyword(s):  
The Novel ◽  
Harmonic Drive ◽  
Design And Optimization ◽  
Forced Wave ◽  
Gap Ratio ◽  
Optimal Value ◽  
Wave Generator ◽  
Computational Fluid Dynamics Cfd ◽  
Lubrication Characteristics ◽  
Cfd Method

In contrast to the conventional forced wave generator which consists of cam and flexible bearing in harmonic drive, the novel forced wave generator retains cam but cancels flexible bearing. In this article, the lubrication characteristics of the novel forced wave generator in harmonic drive is studied. First, an elliptical sliding bearing (ESB) model of simplified structure between the novel forced wave generator and the flex spline is established. Further, the computational fluid dynamics (CFD) method is employed to study the effect of some factors on the lubrication characteristics of the ESB model including elliptical gap ratio, width, and rotational speed. According to the analysis, the elliptical gap ratio has a great impact and its optimal value is 3, which is used in the design of the novel forced wave generator. Last, the practical design of the novel forced wave generator in harmonic drive is given, which can provide a basis for design and optimization of a forced wave generator without flexible bearing of the harmonic drive.

scholarly journals Vitalie Bârca, Notes on the origin and dating of the bone pyxides from the Sarmatian environment between the Don and the Prut

2019 ◽  
Vol 7 (2) ◽  
pp. 129-155
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
New Wave ◽  
North West ◽  
The North ◽  
Group Belonging ◽  
Local Work ◽  
Made In ◽  
Grave Goods

The object of this article is to discuss the bone pyxides discovered in the Sar¬matian graves from the north and north-west of the Black Sea. The study, with¬out being exhaustive, attempts a presentation of the graves where bone pyxides were identified, but also of the cultural environments where similar toiletry piec¬es were used. The conclusion is that bone pyxides in Sarmatian graves from the north and north-west Pontic territory are mainly Roman products. Nonetheless, it is not excluded that some pyxides are copies of the first, made in local work¬shops (north-Pontic). The author notes that all Sarmatian graves containing bone pyxides date, on the basis of grave goods, to the second half of the 1st – early/first decades of the 2nd c. AD. Furthermore, it is noted they are usually part of the grave group belonging to the new wave of Sarmatians arriving to the north-Pontic area starting with mid 1st c. AD from east of the Don and that in the second half of the 1st – first decades of the 2nd c. AD they form a well marked local cultur¬al-chronological horizon. Last but not least, the author notes that pyxides are part of funerary features dating to the period of major inflow of Roman artifacts to the Sarmatian environment set between AD 60/70 – 120/130.

scholarly journals Kinematic error of a harmonic drive

2018 ◽  
Vol 224 ◽  
pp. 01039 ◽  
Author(s):  
Igor Lyuminarsky ◽  
Stanislav Lyuminarsky
Keyword(s):  
Mathematical Model ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Elastic Interactions ◽  
Wave Generator ◽  
Flexible Gear

The article deals with the causes for kinematic error of harmonic drives. The error was determined theoretically using a mathematical model of a drive accounting elastic interactions of the drive elements. The paper identifies the main cause for the inherent kinematic error of a harmonic drive featuring a cam wave generator: a variation in a flexible gear deformation at rolling of flexible bearing balls. It was established that the highest kinematic error of a drive is significantly lower than the first harmonic of a flexible gear generating error. There is obtained a cam displacement dependence of the highest kinematic error for VZP-80 drive.

The Influence of the Angular Coordinate of a Fixed Gear Wheel on the Kinematic Error of a Harmonic Drive

2019 ◽  
pp. 3-8
Author(s):  
I.E. Lyuminarsky ◽  
S.E. Lyuminarsky ◽  
Y.S. Ivanov
Keyword(s):  
Angular Position ◽  
Gear Wheel ◽  
Elastic Interaction ◽  
Design Stage ◽  
Theoretical Studies ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Accuracy Class ◽  
Wave Generator ◽  
Manufacturing Errors

When designing harmonic drives, it is important to address the issue of reducing the kinematic error of the drive occurring due to the deformation of the flexible gear, radial oscillations of the cam, manufacturing and installation errors of the gears. Conventionally, this problem is solved by increasing the accuracy class of the gears and the parts where manufacturing errors impact the accuracy of cam installation. A mathematical model is proposed that enables researchers to study the dependency of the kinematic error of the harmonic drive on various factors already at the design stage. Calculation techniques are developed that take into account elastic interaction between the main elements of the drive as well as manufacturing and installation errors. The results of theoretical studies of the influence of the angular position of the flexible and rigid gears on the kinematic error of a harmonic drive with a cam wave generator are presented. The possibility of reducing the kinematic error by turning the fixed gear is proven.

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