scholarly journals Research on the Possibility of Lowering the Manufacturing Accuracy of Cycloid Transmission Wheels with Intermediate Rolling Elements and a Free Cage

2021 ◽  
Vol 12 (1) ◽  
pp. 5
Author(s):  
Egor A. Efremenkov ◽  
Nikita V. Martyushev ◽  
Vadim Yu Skeeba ◽  
Maria V. Grechneva ◽  
Andrey V. Olisov ◽  
...  
Keyword(s):  
High Accuracy ◽  
Transmission Mechanism ◽  
Ring Rolling ◽  
Distribution Law ◽  
Production Methods ◽  
Probabilistic Distribution ◽  
Rolling Element ◽  
Rolling Elements ◽  
Manufacturing Accuracy ◽  
The Cost

Purpose: In the present work, different combinations of fits and accuracies, in relation to the profiles of mating parts, have been analysed in order to assess the degree of the engagement of transmissions that contain intermediate rolling elements. The aim of this work is to determine which fits have decreased accuracy, but nevertheless provide a minimum manufacturing clearance for the transmission engagement in order to reduce the cost of parts production. Methods and materials: Considering the normal probabilistic distribution law in relation to the obtained dimensions of the manufacturing equipment, a combination of fits were selected using the incomplete interchangeability method, taking into account the peculiarities of the cycloid engagement in transmissions with intermediate rolling elements (IRE). Results: Having studied various combinations of fits of parts that are engaged in transmissions with intermediate rolling elements and a free cage (IREFC), a combination of fits for a “ring, rolling-element cam” were determined, in which a technological clearance of 3 µm is formed in the engagement. At the same time, cycloid disk profiles are manufactured according to the 9th tolerance grade, which reduces the laboriousness and cost of the production. Discussion. When reducing the manufacturing accuracy of cycloid disks, it is possible to obtain both very ample clearances and significant negative allowances. For example, having manufactured a ring with the H9 fit, rolling elements with h6 and a cam with js9, the maximum manufacturing clearance can reach 0.086 mm, while the clearance limits vary from 0.025 mm to 0.061 mm. Additionally, if mating parts are manufactured using a combination of K9-h6-js9 fits, a negative allowance varying from 0.014 mm to 0.026 mm will emerge in the engagement. Both described cases are unacceptable because both ample clearances and large negative allowances will negatively influence the working capacity of the mechanism. However, it is possible to select a combination of fits using the 9th tolerance grade of the basic parts, by which the parts will contact in the range from a small negative allowance of 1 µm to a clearance of 3–4 µm. Furthermore, if this is considered, taking into account the machine settings, it is possible to obtain parts according to the 9th accuracy tolerance grade and, at the same time, provide a clearance in the engagement that is almost equal to zero. Moreover, such a combination of fits is relevant for any transmission with IRE. This is a positive result because it reduces the laboriousness when manufacturing parts and, at the same time, provides high accuracy of the mechanism. Conclusions: It has been established that when lowering the accuracy of manufacturing transmission parts with IRE, both clearances and negative allowances may occur in the engagement, depending on the combination of fits. At the same time, it is possible to select such a combination of fits, by which the parts manufactured according to the 9th tolerance grade, will provide almost zero clearance of the engagement of the transmission. In this way, it is possible to reduce the cost of manufacturing the parts for gears with intermediate rolling elements and, at the same time, maintain a high accuracy of the transmission mechanism.

Contour Extraction of Cerebrovascular Based on Maximum Optimization Cost

2011 ◽  
Vol 204-210 ◽  
pp. 1415-1418
Author(s):  
De Jiang Zhang ◽  
Na Na Dong ◽  
Xiao Mei Lin
Keyword(s):  
Dynamic Programming ◽  
Blood Vessel ◽  
High Efficiency ◽  
High Accuracy ◽  
Differential Method ◽  
Cost Curve ◽  
Contour Extraction ◽  
Target Image ◽  
The Cost ◽  
Conventional Algorithm

By studying the conventional algorithm of contour extraction, a new method of contour extraction in blood vessel of brain is proposed based on the MOC maximum optimization cost. First of all, the theory computes the gray differential of the image by conventional differential method to build the cost space. Then, by using dynamic programming theory, the maximum optimization cost curve in the space is extracted to serve as the specific cerebrovascular profile. The experiments show that this method ensures high efficiency in extracting cerebrovascular contour and a high accuracy in positioning cerebrovascular contour, and it diminishes the target image ambiguity caused by noise to improve the anti-interference ability of Contour extraction.

Rolling Element Bearing Non-Linearity Effects

2000 ◽  
Author(s):  
N. S. Feng ◽  
E. J. Hahn
Keyword(s):  
Equations Of Motion ◽  
Rolling Element Bearing ◽  
Radial Clearance ◽  
Rotor Systems ◽  
Bearing Life ◽  
Rolling Element ◽  
Bearing Load ◽  
Rolling Elements ◽  
Element Bearing ◽  
Negative Clearance

Non-linearity effects in rolling element bearings arise from two sources, viz. the Hertzian force deformation relationship and the presence of clearance between the rolling elements and the bearing races. Assuming that centrifugal effects may be neglected and that the presence of axial preload is appropriately reflected in a corresponding change in the radial clearance, this paper analyses a simple test rig to illustrate that non-linear phenomena such as synchronous multistable and nonsynchronous motions are possible in simple rigid and flexible rotor systems subjected to unbalance excitation. The equations of motion of the rotor bearing system were solved by transient analysis using fourth order Runge Kutta. Of particular interest is the effect of clearance, governed in practice by bearing specification and the amount of preload, on the vibration behaviour of rotors supported by ball bearings and on the bearing load. It is shown that in the presence of positive clearance, there exists an unbalance excitation range during which the bearing is momentarily not transmitting force owing to contact loss, resulting in rolling element raceway impact with potentially relatively high bearing forces; and indicating that for long bearing life, operation with positive clearance should be avoided in the presence of such unbalance loading. Once the unbalance excitation is high enough to avoid such contact loss, it is the bearings with zero or negative clearance which produce maximum bearing forces.

Global load determination in linear guides based on the fusion of local rolling element loads determined from strain sensitive sensor groups

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
David Krampert ◽  
Sebastian Unsleber ◽  
Leonhard Reindl ◽  
Stefan J. Rupitsch
Keyword(s):  
Load Distribution ◽  
Mechanical Load ◽  
Sensor System ◽  
Distribution Model ◽  
Valuable Insight ◽  
Estimation Errors ◽  
Rolling Element ◽  
Rolling Elements ◽  
Load Mode ◽  
Measurement Principle

Abstract Measuring the mechanical load on linear guides provides many possibilities regarding predictive maintenance and process monitoring. In this contribution, we provide an in depth evaluation of a Diamond Like Carbon (DLC) based sensor system integrated into the runner block’s raceway that is capable of directly measuring the load on individual rolling elements. An efficient algorithm based on an Extended Kalman Filter (EKF) for local sensor fusion and load estimation is presented and proven to reliably retrieve the load regardless of the rolling element’s position. Afterwards, we compare locally measured loads to results from a theoretical load distribution model, providing valuable insight into modeling parameters and a verification of the sensor measurement principle. In a final step, an algorithm to invert the load distribution model is derived and used for an evaluation of the sensor system, achieving Root-Mean-Square (RMS) estimation errors of equivalently 1.4 kN in the preload range and 2.75 kN overall for one dimensional loads. Load mode distinction was equally successful with a suppression RMS error of 0.7 kN in the preload range and 2.87 kN in total.

The Monitoring of the Bearing Nodes with Excessive Radial Clearances Using the FAM-C and FDM-A Methods

2009 ◽  
Vol 25 (1) ◽  
pp. 109-127 ◽  
Author(s):  
Andrzej Gębura ◽  
Tomasz Tokarski
Keyword(s):  
Resonant State ◽  
Lubricant Film ◽  
Rolling Element Bearings ◽  
Mechanical Verification ◽  
Macro Scale ◽  
Rolling Element ◽  
Rolling Elements ◽  
Diagnostic Work ◽  
Theoretical Analyses

The Monitoring of the Bearing Nodes with Excessive Radial Clearances Using the FAM-C and FDM-A Methods The paper has been intended to present findings resulting from the monitoring of the bearing support elements with increased radial clearances with the FAM-C1 and FDM-A2 methods. The role the lubricant film plays in this type of the rolling-elements' wear has been described. Discussed are symptoms, parameters, and hazards to the resonant state in bearing nodes, as well as capabilities of diagnosing them with the FAM-C and FDM-A methods. Hypotheses about subsequent stages of the wearing process in aircraft turbojet engine's bearing support assemblies, including how the resonant state occurs, have been presented. The mechanism of the resonance in rolling-element bearings has been described, with particular attention paid to the effects of gyrostatic moments upon the bearing support elements, both in micro- and macro-scale. Theoretical analyses have been supplemented with findings resulting from the diagnostic work carried out by the Authors, and with data from the mechanical verification of engines in the course of the authorised dismantling thereof.

Dynamic Interactions Between the Rolling Element and the Cage in Rolling Bearing Under Rotational Speed Fluctuation Conditions

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Wenbing Tu ◽  
Ya Luo ◽  
Wennian Yu
Keyword(s):  
Dynamic Model ◽  
Rotational Speed ◽  
Rolling Bearing ◽  
Nonlinear Dynamic Model ◽  
Dynamic Interactions ◽  
Interaction Forces ◽  
Rolling Element ◽  
Speed Fluctuation ◽  
Rolling Elements ◽  
Fluctuation Frequency

Abstract A nonlinear dynamic model is proposed to investigate the dynamic interactions between the rolling element and cage under rotational speed fluctuation conditions. Discontinuous Hertz contact between the rolling element and the cage and lubrication and interactions between rolling elements and raceways are considered. The dynamic model is verified by comparing simulation result with the published experimental data. Based on this model, the interaction forces and the contact positions between the rolling element and the cage with and without the rotational speed fluctuation are analyzed. The effects of fluctuation amplitude, fluctuation frequency, and cage pocket clearance on the interaction forces between the rolling element and the cage are also investigated. The results show that the fluctuation of the rotational speed and the cage pocket clearance significantly affects the interaction forces between the rolling element and the cage.

Traction Characteristics of a Rolling Element Bearing Under Rapid Acceleration and Implications for Auxiliary Operation in Magnetic Bearing Systems

2006 ◽  
Author(s):  
Matthew O. T. Cole ◽  
Theeraphong Wongratanaphisan
Keyword(s):  
Dynamic Behavior ◽  
Magnetic Bearing ◽  
Rolling Element Bearing ◽  
Elastic Behavior ◽  
Friction Forces ◽  
Auxiliary Operation ◽  
Rolling Element ◽  
Rolling Elements ◽  
Auxiliary Bearing ◽  
Bearing Assembly

The application of rolling element bearings for auxiliary operation in magnetic bearing systems is quite common, yet such operation is very different to that for which standard bearings are designed. During initial touchdown of a spinning rotor with an auxiliary bearing, rapid acceleration of the bearing inner race results in large inertial and friction forces acting on the rolling elements. Complex dynamic behavior of the bearing assembly and resulting traction forces are difficult to predict but, nonetheless, have important implications for both rotor dynamic behavior and thermo-elastic behavior of the bearing components. The aim of this work is to obtain an insight into bearing behavior by analyzing component interaction forces that would arise based on the assumption that the overall bearing traction torque is dependent only on instantaneous load, speed and acceleration. How such an analysis can be verified by experimental measurements of traction during rapid acceleration is discussed and some initial experimental results are presented. The implications for modeling and prediction of rotor-magnetic bearing system behavior during touchdown are also discussed.

scholarly journals Price Transmission Mechanism of Transit Service in City

2012 ◽  
Vol 5 ◽  
pp. 44-49
Author(s):  
Guang Lin Sun ◽  
Jian Wang
Keyword(s):  
Transmission Mechanism ◽  
Price Transmission ◽  
Demand Elasticity ◽  
Transmission Network ◽  
Transit Service ◽  
Distinct Mechanism ◽  
Integration Test ◽  
Augmented Dickey Fuller ◽  
The Cost ◽  
The Relationship

Price transmission of transit service is a distinct mechanism with common characters. This paper aims to provide the nature and law of price transmission of transit service. The transmission of transit service prices is defined and transmission routes are classified into vertical and horizontal. The cost-push and demand-push are to drive the price carriers along transmission routes, which produces the price transmission network. Augmented Dickey-Fuller (ADF) and Granger co-integration test are used to measure the cost-push price transmission. For demand-push price transmission, the demand elasticity was used to model the relationship between transit demand and prices.

An Intelligent Real Time Design Methodology for Component Selection: An Approach to Managing Uncertainty

1994 ◽  
Vol 116 (4) ◽  
pp. 980-988 ◽  
Author(s):  
S. R. Bradley ◽  
A. M. Agogino
Keyword(s):  
Real Time ◽  
Design Methodology ◽  
Limited Resources ◽  
Rolling Element Bearings ◽  
Component Selection ◽  
Rolling Element ◽  
Improved Design ◽  
The Cost ◽  
Component Database ◽  
Selection Of

An Intelligent Real Time Design (IRTD) methodology is presented for component selection applications under the reality of uncertain and incomplete information. A decision analytic approach is developed with the goal of assisting designers in making decisions that balance the cost of the limited resources consumed during the design process, such as the designer’s time, against the benefit to be derived from the utilization of those resources in terms of expectations of an improved design. This approach is shown to complement other formal methods for design based on interval arithmetic and qualitative optimization, and a general methodology is proposed for performing component selection utilizing a combination of these methods. An example application to the selection of rolling element bearings is presented to clarify the methodology and demonstrate its effectiveness in providing guidance to designers when selecting elements from a component database.

Ceramics in Rolling Element Bearings

1979 ◽  
Author(s):  
C. F. Bersch ◽  
Philip Weinberg
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
Cooling System ◽  
Extreme Environment ◽  
Ball Bearings ◽  
Rolling Element Bearings ◽  
Turbine Engine ◽  
Rolling Element ◽  
Rolling Elements ◽  
History Of

The feasibility of using hot-pressed silicon nitride (HPSN) for rolling elements and for races in ball bearings and roller bearings has been explored. HPSN offers opportunities to alleviate many current bearing problems including DN and fatigue life limitations, lubricant and cooling system deficiencies, and extreme environment demands. The history of ceramic bearings and the results of various element tests, bearing tests in rigs, and bearing tests in a turbine engine will be reviewed. The advantages and problems associated with the use of HPSN in rolling element bearings will be discussed.

scholarly journals Component Hardness Differences and Their Effect on Bearing Fatigue

1967 ◽  
Vol 89 (1) ◽  
pp. 47-54 ◽  
Author(s):  
E. V. Zaretsky ◽  
R. J. Parker ◽  
W. J. Anderson
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
Load Capacity ◽  
Full Scale ◽  
Contact Temperature ◽  
Rolling Element Bearings ◽  
Rolling Element ◽  
Rolling Elements ◽  
Compressive Residual Stresses

The five-ball fatigue tester and full-scale rolling-element bearings were used to determine the effect of component hardness differences of SAE 52100 steel on bearing fatigue and load capacity. Maximum fatigue life and load capacity are achieved when the rolling elements of a bearing are one to two points (Rockwell C) harder than the races. There appears to be an interrelation among compressive residual stresses induced in the races during operation, differences in component hardness, and fatigue life. Differences in contact temperature and plastically deformed profile radii could not account for differences in fatigue life.

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