Optimized tooth root strength by controlled shot peening

2019 ◽  
pp. 137-148
Author(s):  
J. Hoffmeister ◽  
J. Hermes
Keyword(s):  
Shot Peening ◽  
Tooth Root ◽  
Root Strength

The Effect of Notches at the Tooth Root Fillet on the Endurance Strength of Gears

1978 ◽  
Vol 100 (3) ◽  
pp. 417-422
Author(s):  
H. Winter ◽  
X. Wirth
Keyword(s):  
Shot Peening ◽  
Calculation Procedure ◽  
Special Importance ◽  
Spur Gears ◽  
Tooth Root ◽  
Characteristic Parameters ◽  
Uniform Heat ◽  
Endurance Strength

Notches at the tooth root fillet can be caused by shaving or grinding. The influence of different notches at the root fillet on the endurance strength of case hardened spur gears was investigated in back-to-back tests and pulsator tests. Data of the test gears: MnCr and CrNi Steels, module 3 (8 DP) and module 8 (3 DP). Besides the a.m. tests photo elastic investigations were performed. On the basis of some characteristic parameters, it was possible, to find a calculation procedure, to determine the loss of endurance strength due to the effect of various kinds of notches. Moreover it was investigated to what extent the endurance strength of notched gears could be increased by regrinding or shot peening the root fillet. It is known that notches at the tooth root fillet can essentially reduce the endurance strength of gears. This is of special importance for case hardened gears. It is desirable that such notches should be avoided, but sometimes notches are produced by shaving or grinding due to inadequacy of tooling or non-uniform heat distortion. Therefore the influence of geometry and position of notches at the root fillet on the endurance of case hardened spur gears was investigated in back-to-back and pulsator tests. Additionally the extent the endurance strength of notched gears could be increased by regrinding or shot peening the root fillets was studied.

Comparative Analysis of Tooth-Root Strength Using ISO and AGMA Standards in Spur and Helical Gears With FEM-based Verification

2005 ◽  
Vol 128 (5) ◽  
pp. 1141-1158 ◽  
Author(s):  
Andrzej Kawalec ◽  
Jerzy Wiktor ◽  
Dariusz Ceglarek
Keyword(s):  
Comparative Analysis ◽  
Engineering Practice ◽  
Tooth Root ◽  
Helical Gears ◽  
Gear Design ◽  
Current Trends ◽  
Wide Range ◽  
Location Parameters ◽  
Root Strength ◽  
And Performance

Current trends in engineering globalization require researchers to revisit various normalized standards that determine “best practices” in industries. This paper presents comparative analysis of tooth-root strength evaluation methods used within ISO and AGMA standards and verifying them with developed models and simulations using the finite element method (FEM). The presented analysis is conducted for (1) wide range of spur and helical gears manufactured using racks or gear tools; and for (2) various combinations of key geometrical (gear design), manufacturing (racks and gear tools), and performance (load location) parameters. FEM of tooth-root strength is performed for each modeled gear. FEM results are compared with stresses calculated based on the ISO and AGMA standards. The comparative analysis for various combinations of design, manufacturing, and performance parameters are illustrated graphically and discussed briefly. The results will allow for a better understanding of existing limitations in the current standards applied in engineering practice as well as provide a basis for future improvements and/or unifications of gear standards.

scholarly journals Study on the Influence Coefficient of Residual Stress used to Estimate the Stress Life Curve of Gears

2020 ◽  
Author(s):  
Zhen Wang ◽  
Long Chen ◽  
Zhong-Ming Liu ◽  
Jun-Wei Cheng
Keyword(s):  
Residual Stress ◽  
Crack Propagation ◽  
Fatigue Test ◽  
Shot Peening ◽  
Calculated Data ◽  
Labor Cost ◽  
Step Function ◽  
Influence Coefficient ◽  
Tooth Root ◽  
Crack Propagation Process

Abstract This study aims to estimate the gear S-N curve by the influence coefficient m of the residual stress at the root of the gear for providing theoretical basis and experimental support for the study of the bending fatigue performance of the gear. Based on the crack propagation theory and the linear damage accumulation theory, according to the Goodman relation, the residual stress is treated as the average stress. The spatial distribution of the residual stress is considered, and the residual stress is treated as a step function about depth, so the crack propagation process is divided into several stages. Through the fatigue test, the S-N curve of the gear is obtained. In order to avoid the influence of gear material and shape on the coefficient m, the S-N curve after heat treatment is used as the initial S-N curve, and the S-N curve after shot peening is used as the result curve. Through S-N curve, the influence coefficient m of tooth root residual stress is calculated, and the S-N curve of gears after shot peening is deduced by m value, which is compared with the S-N curve obtained by experiment. The influence coefficient m of residual stress calculated by S-N curve is 0.2132. The S-N curve of shot peening derived from m value is lnS=7.6963-0.0821lnN, which is consistent with the trend of S-N curve obtained by experiment, and the calculated data are more secure in the case of high cycle fatigue. The huge capital and labor cost of gear fatigue test can be saved by estimating gear S-N curve more accurately by m value. It provides a theoretical and experimental basis for the study of the influence coefficient of tooth root residual stress, and provides a solution for estimating the gear S-N curve.

A model approach for considering nonmetallic inclusions in the calculation of the local tooth root load-carrying capacity of high-strength gears made of high-quality steels

2019 ◽  
Vol 233 (21-22) ◽  
pp. 7309-7317 ◽  
Author(s):  
D Fuchs ◽  
S Schurer ◽  
T Tobie ◽  
K Stahl
Keyword(s):  
Carrying Capacity ◽  
Nonmetallic Inclusions ◽  
High Strength ◽  
Steel Matrix ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Strength Based ◽  
Load Carrying ◽  
Root Strength ◽  
Gear Steels

Demands for higher performance have caused a need for improved component characteristics, e.g. through surface strengthening of gears and increased cleanliness of gear steels. Unfortunately, a resultant drawback is that cracks in such high-strength gears are more often initiated in the material matrix at nonmetallic inclusions and not at the surface. In standardized calculation methods, the degree of cleanliness of steels is not yet directly correlated to the tooth root load-carrying capacity. This paper considers the effects of nonmetallic inclusions in the steel matrix on the tooth root strength based on the theoretical approach of Murakami.

Strength Optimization Design of a Helical Hydraulic Rotary Actuator

2012 ◽  
Vol 544 ◽  
pp. 139-144
Author(s):  
Yu Yang ◽  
Xing Guo ◽  
Shu Dong Yang ◽  
Tao Xu
Keyword(s):  
Motion Control ◽  
Optimization Design ◽  
Tooth Root ◽  
Compact Structure ◽  
Pressure Angle ◽  
Output Torque ◽  
Rotary Actuator ◽  
Root Strength ◽  
Thread Root ◽  
Large Output

A helical hydraulic rotary actuator for part-turn motion control is presented. Because of its compact structure and large output torque, strength study for the helical hydraulic rotary actuator becomes very necessary. Using AWE, influences of multi-start thread engagement length, thread start number, spline pressure angle and piston material on strength of the actuator’s key parts are studied in depth, so as to optimize the actuator’s strength and structure. The results show that the influences of nut width, thread start number and piston material on multi-start thread root strength of nut are notable, the influence of pressure angle on spline tooth root strength of output shaft is visible, and stress concentration on multi-start thread root and spline tooth root is very obvious.

Tooth Root Strength of Spur and Helical Gears Manufactured With Gear-Shaper Cutters

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Andrzej Kawalec ◽  
Jerzy Wiktor
Keyword(s):  
Geometric Analysis ◽  
Strength Analysis ◽  
Tooth Root ◽  
Element Analysis ◽  
Iso Standard ◽  
Transmission Design ◽  
Root Strength ◽  
Gear Manufacturing ◽  
Tip Radius ◽  
Root Stress

At the beginning of gear transmission design, mainly simplified methods of gear strength analysis based on ISO or AGMA standards are used. However, they allow for calculation of approximate and sometimes biased stresses. Moreover, ISO standard is generally focused on using racks for gear manufacturing. A method proposed in this paper allows for computation of the parameters of critical section, strength coefficients YF, YS, and tooth root stress σF according to the procedure from ISO standard also in the case of machining gears with gear type tools. The proposed improvement of ISO standard leads to replacement of real gear tool with rack with substitute tip radius ρa0*. The developed method maintains basic assumptions and advantages of ISO standard, including its simplicity. Simultaneously, it allows for computing the maximum tooth root stresses σF: (i) very close to results of accurate geometric analysis and finite element analysis, and (ii) much closer, compared to conventional ISO procedure, to results obtained using AGMA standard.

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