EFFECT OF STRAIGHT-LINE MECHANISM DESIGN ON THE LOAD DISTRIBUTION IN A CYCLOIDAL GEAR

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 35-42
Author(s):  
Henryk DUDA ◽  
Bogdan WARDA
Keyword(s):  
Fatigue Life ◽  
Mechanism Design ◽  
Load Distribution ◽  
Output Shaft ◽  
Simulation Program ◽  
Force Loading ◽  
Eccentric Shaft ◽  
Straight Line ◽  
Straight Line Mechanism

In the cycloidal gear, the torque is transmitted to the planet gears via an eccentric shaft with central bearings mounted on it. A straight-line mechanism is used to output the torque from the planet gears to the output shaft, a mechanism which consists of rotational sleeves mounted on the pins rigidly connected to the output shaft disc. These sleeves roll off in the holes of the planetary wheel. The forces generated in the straight-line mechanism affect the distribution of forces in the cycloid gearing and the amount of force loading the central bearing. The article presents the influence of the number of bolts of the straight-line mechanism on the load distribution in the cycloidal gear. The research carried out with the simulation program has shown that the smaller the number of pins, the greater the fluctuation of the force acting in the central bearing and the greater unevenness of force distributions in the cycloidal gear. This unevenness may cause a decrease in fatigue life of the meshing and central bearings.

Analytical determination of the optimal clearance for the fatigue life of ball bearing under different load conditions

2021 ◽  
pp. 1-28
Author(s):  
Bin Fang ◽  
Jinhua Zhang
Keyword(s):  
Fatigue Life ◽  
Load Distribution ◽  
Life Prediction ◽  
Ball Bearing ◽  
Operating Conditions ◽  
Analytical Determination ◽  
Parameters Selection ◽  
Bearing Life ◽  
Structural Design Optimization ◽  
Load Conditions

Abstract In this paper, a comprehensive analytical model for the fatigue life prediction of ball bearing in various operating conditions is presented. Not only the internal clearance variations induced by the centrifugal expansion and assembly interference, but also ball inertia forces and ball-raceway separations are fully considered in theoretical modeling to achieve accurate life prediction of ball bearing. The model has been validated by comparison with the static results in previous literature. Based on this, the results of the load distribution and fatigue life versus the internal clearance of ball bearing under various operating conditions are studied. The results show that there is always an optimal clearance to maximize bearing fatigue life for the radial load or the combined load conditions, and the size of the optimal clearance for bearing life is determined by both the load conditions and rotating speeds to ensure the uniformity of the internal load distribution of the ball bearing. Therefore, the above theoretical and conclusions can be used in structural design optimization and assembly parameters selection of ball bearing to maximize the life characteristic.

Design and Development of a Novel Infant Surgical Table for 4-DOF Patient Manipulation

2007 ◽  
Author(s):  
Kimberly Ryland ◽  
Carl A. Nelson ◽  
Thomas Hejkal
Keyword(s):  
Premature Infants ◽  
Laser Photocoagulation ◽  
Occupational Injury ◽  
Quality Care ◽  
Blood Vessel Development ◽  
Locking Mechanism ◽  
Straight Line ◽  
Vessel Development ◽  
Straight Line Mechanism ◽  
Standard Table

Retinopathy of Prematurity, caused by abnormal blood vessel development in the retina of premature infants, is a leading cause of childhood blindness. It is treated using laser photocoagulation. Current methods require the surgeon to assume awkward standing positions, which can result in injury to the surgeon if repeated often. To assist surgeons in providing quality care and prevent occupational injury, a new infant surgical table was designed. The engineered solution is an attachment to a standard surgical table, saving cost and space. This takes advantage of the adjustable height and tilt provided by the standard table, while 360° rotation designed into the attachment allows the surgeon to sit during surgery. The critical cords and tubes are routed through the attachment to avoid pulling and kinking. A four-bar locking mechanism allows easy attachment to standard medical railing. Finally, a straight line mechanism provides positive locking of the rotation, allowing precise positioning of the infant.

Fatigue Life Prediction for Large-Diameter Elastically Constrained Ball Bearings

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Jerzy T. Sawicki ◽  
Samuel A. Johansson ◽  
John H. Rumbarger ◽  
Ronald B. Sharpless
Keyword(s):  
Fatigue Life ◽  
Load Distribution ◽  
Life Prediction ◽  
Large Diameter ◽  
Roller Bearing ◽  
Fatigue Life Prediction ◽  
Design Criteria ◽  
Standard Design ◽  
Critical Components ◽  
Bearing Rings

The application of large-diameter bearing rings and the thereof inherited low stiffness make them susceptible to local distortions caused by their surrounding structures, which are often under heavy loads. The standard accepted design criteria for these bearings are based on the estimation of the internal load distribution of the bearing, under the assumption of rigid circular and flat supporting structures, that keep the bearing inner and outer races in circular, flat, i.e., not deformed shapes. However, in the presence of structural distortions, the element load distribution can be severely altered and cannot be predicted via the standard design criteria. Therefore, the application of large-diameter ball and roller bearing rings as the critical components in rotating machines becomes more of a design task than making a catalog selection. The analytical and finite element approach for fatigue life prediction of such a bearing application is presented. The undertaken approach and the results are illustrated based on the analysis and fatigue life simulation of the computed tomography scanner’s main rotor bearing. It has been demonstrated that flexibility of the rings can significantly reduce the fatigue life of the ball bearing.

Mathematical Model for Face-Hobbed Straight Bevel Gears

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Yi-Pei Shih
Keyword(s):  
Mathematical Model ◽  
Bevel Gear ◽  
Tooth Contact Analysis ◽  
Rolling Circle ◽  
High Productivity ◽  
Bevel Gears ◽  
Straight Line ◽  
Base Circle ◽  
Straight Line Mechanism ◽  
Straight Lines

Face hobbing, a continuous indexing and double-flank cutting process, has become the leading method for manufacturing spiral bevel gears and hypoid gears because of its ability to support high productivity and precision. The method is unsuitable for cutting straight bevel gears, however, because it generates extended epicycloidal flanks. Instead, this paper proposes a method for fabricating straight bevel gears using a virtual hypocycloidal straight-line mechanism in which setting the radius of the rolling circle to equal half the radius of the base circle yields straight lines. This property can then be exploited to cut straight flanks on bevel gears. The mathematical model of a straight bevel gear is developed based on a universal face-hobbing bevel gear generator comprising three parts: a cutter head, an imaginary generating gear, and the motion of the imaginary generating gear relative to the work gear. The proposed model is validated numerically using the generation of face-hobbed straight bevel gears without cutter tilt. The contact conditions of the designed gear pairs are confirmed using the ease-off topographic method and tooth contact analysis (TCA), whose results can then be used as a foundation for further flank modification.

The Effect of Misalignment on the Fatigue Life of Tapered Roller Bearings

1972 ◽  
Vol 94 (2) ◽  
pp. 181-186 ◽  
Author(s):  
H. Zantopulos
Keyword(s):  
Experimental Study ◽  
Fatigue Life ◽  
Test Data ◽  
Load Distribution ◽  
Roller Bearings ◽  
Bearing Life ◽  
Life Tests ◽  
Tapered Roller ◽  
Tapered Roller Bearings ◽  
Sufficient Test

A comprehensive analytical and experimental study of the effect of misalignment on load distribution and fatigue life of tapered roller bearings is presented. Included are the effects of truncation of crowned rollers and edge of contact stresses. Bearing life tests, involving approximately 500 bearings, were run at various loads and misalignments to obtain sufficient test data to substantiate the analytical results.

scholarly journals Experimental Method for Plotting S-N Curve with a Small Number of Specimens

2016 ◽  
Vol 23 (4) ◽  
pp. 129-137 ◽  
Author(s):  
Przemysław Strzelecki ◽  
Janusz Sempruch
Keyword(s):  
Fatigue Life ◽  
Least Squares Method ◽  
Experimental Results ◽  
Bending Test ◽  
Likelihood Method ◽  
Staircase Method ◽  
Random Occurrence ◽  
Straight Line ◽  
Standard Documents ◽  
Time Required

Abstract The study presents two approaches to plotting an S-N curve based on the experimental results. The first approach is commonly used by researchers and presented in detail in many studies and standard documents. The model uses a linear regression whose parameters are estimated by using the least squares method. A staircase method is used for an unlimited fatigue life criterion. The second model combines the S-N curve defined as a straight line and the record of random occurrence of the fatigue limit. A maximum likelihood method is used to estimate the S-N curve parameters. Fatigue data for C45+C steel obtained in the torsional bending test were used to compare the estimated S-N curves. For pseudo-random numbers generated by using the Mersenne Twister algorithm, the estimated S-N curve for 10 experimental results plotted by using the second model, estimates the fatigue life in the scatter band of the factor 3. The result gives good approximation, especially regarding the time required to plot the S-N curve.

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