The surface condition of a carburized gear is improved by CBN grinding, in addition to the generation of a compressive residual stress at the ground surface. To clarify the effect of these merits on the strength enhancement, a bending fatigue test is performed for the carburized and the CBN-ground gears. The fillet as well as involute tooth surface is ground by an electroplated threaded CBN wheel. The low axial feed rate and the spark-out treatment are effective in improving the surface finish and increasing the compressive residual stress, and the strengths of CBN-ground gears are increased from 100 MPa to 160 MPa in comparison with the carburized gears. Moreover, the test results are discussed on the basis of the fracture mechanics-based strength evaluation which has been proposed by the authors. This analysis demonstrates that the influence of CBN grinding on strength is smaller than the effects of surface-treatments such as shot peening and chemical polishing.

1.
Aida
T.
,
Oda
S.
,
Kusano
K.
, and
Ito
Y.
,
1967
, “
Bending Fatigue Strength of Gears
,”
Trans. JSME (in Japanese)
, Vol.
33
, pp.
1314
1320
.
2.
Besuner, P. M., 1976, “Residual Life Estimates for Structures with Partial Thickness Cracks,” Mechanics of Crack Growth, ASTM STP590, pp. 403–419.
3.
Drago
R. J.
,
1990
, “
Comparative Load Capacity Evaluation on CBN-Finished Gears
,”
Gear Technology
, Vol.
7
, pp.
8
48
.
4.
Inoue, K., Kato, M., and Yamanaka, M., 1989, “Fatigue Strength and Crack Growth of Carburized and Shot Peened Spur Gears,” Proceedings of the International Power Transmission and Gearing Conference, Vol. 2, ASME Book No. 10288B, pp. 663–668.
5.
Inoue, K., Lyu, S., Kato, M., Onishi, M., and Shimoda, K., 1994, “Effects of Surface Condition on Bending Strength of Carburized Gear Teeth,” Proceedings of 1994 International Gearing Conference, UK National Gear Metrology Laboratory, pp. 183–188.
6.
Inoue, K., Lyu, S., Gang, D., and Kato, M., 1996, “Fracture Mechanics Based Evaluation of the Effect of Surface Treatments on the Strength of Carburized Gears,” Proceedings of the International Conference on Gears, VDI-Berichte 1230, pp. 357–369.
7.
ISO 53, 1974, “Cylindrical Gears for General and Heavy Engineering-Basic Rack”.
8.
ISO 6336-3, 1996, “Calculation of Load Capacity of Spur and Helical Gears—Part 3: Calculation of Tooth Bending Strength”.
9.
Johnson
G.
, and
Ratterman
E.
,
1988
, “
Enhanced Product Performance Through CBN Grinding
,”
Gear Technology
, Vol.
5
, pp.
23
33
.
10.
JSME S002, 1981, “Standard Method of Statistical Fatigue Testing (in Japanese)”.
11.
Kato, M., Deng, G., Inoue, K., and Takatsu, N., 1993, “Evaluation of the Strength of Carburized Spur Gear Teeth Based on Fracture Mechanics,” JSME International Journal Ser. C, 161.36, pp. 233–240.
12.
Ko¨nig
W.
,
Mauer
G.
, and
Rober
G.
,
1993
, “
CBN Gear Grinding—A Way to Higher Load Capacity?
,”
Gear Technology
, Vol.
10
, pp.
10
16
.
13.
Little, R. E., 1972, “Estimating the Median Fatigue Limit for Very Small Up-and-Down Quantal Response Tests and for S-N Data with Runouts,” Probabilistic Aspects of Fatigue, ASTM STP 511, pp. 29–42.
14.
Rettig, H., 1969, “Einsatzgehartete Zahnrader,” VDI-Z, Vol. 111, pp. 274–284.
15.
Rice
J. R.
,
1972
, “
Some Remarks on Elastic Crack-Tip Stress Fields
,”
Int. J. Solids Structures
, Vol.
8
, pp.
751
758
.
16.
Tobe, T., Kato, M., and Inoue, K., 1979, “True Stress and Stiffness of Spur Gear Tooth,” Proceedings of the 5th World Congress on Theory of Machines and Mechanisms, Vol. 2, ASME, pp. 1105–1108.
17.
Tobe
T.
,
Kato
M.
,
Inoue
K.
,
Takatsu
N.
, and
Morita
I.
,
1986
, “
Bending Strength of Carburized SCM420H Spur Gear Teeth
,”
Bull. JSME
, Vol.
29
, pp.
273
280
.
18.
Townsend, D. P., and Patel, P. R., 1988, “Surface Fatigue Life of CBN and Vitreous Ground Carburized and Hardened AISA 9310 Spur Gears,” NASA Technical Memorandum 100960 and AVSCOM Technical Report 88-C-019.
19.
Yamanaka, M., Nakamura, H., Emura, T., Wang, L., and Sakaguchi, T., 1994, “Progressing a Productivity of Gear Grinding,” Advancement of Intelligent Production, (Usui, E. Ed.), Elsevier, pp. 253–258.
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