1 Introduction
2 Motivation and research objects
3 Methods and materials
3.1 Test rigs
3.2 Test gears and test variants
Parameter | Symbol | Unit | Test gear | |
---|---|---|---|---|
Flank load carrying capacity | Tooth root bending strength | |||
Normal module | mn | mm | 5 | |
Center distance | a | mm | 91.5 | – |
Number of teeth | z1/z2 | – | 17/18 | 24 |
Face width | b | mm | 14 | 30 |
Normal pressure angle | αn | ° | 20 | |
Helix angle | β | ° | 0 |
Variant | NHD400HV in mm | Two-stage nitriding | Application of grinding |
---|---|---|---|
30CrNiMo8 | 0.8 to 1.0 | 520 °C 15 h KN = 1 | Before nitriding |
31CrMoV9 | Large gearbox application | 530 °C 170 h KN = 0.5 | |
32CDV13 | 0.8 to 1.2 | 520 °C 15 h KN = 1 | |
Aviation application | 570 °C 130 h KN = 0.5 |
3.2.1 Chemical analysis
3.2.2 Gear quality
3.2.3 Hardening depth profiles
Variant | NHD400HV in mm acc. to ISO 6336‑5 [2] | Surface hardness HV0.5 | Core hardness HV0.5 | |
---|---|---|---|---|
30CrNiMo8 | Tooth flank | 0.79 | 634 | 311 |
Tooth root | 0.67 | 622 | ||
31CrMoV9 | Tooth flank | 0.78 | 709 | 309 |
Tooth root | 0.74 | 719 | ||
32CDV13 | Tooth flank | 0.98 | 625 | 337 |
Tooth root | 0.88 | 628 |
3.2.4 Microstructural condition
4 Results and discussion
4.1 Tooth root bending strength
Variant | σF0,pulsator,∞,50% in N/mm2 | σF lim in N/mm2 | Nominal stress numbers (bending) σF lim in N/mm2 acc. to ISO 6336‑5 [2] | ||
---|---|---|---|---|---|
Material quality | Nitriding steels | Case hardened steels | |||
30CrNiMo8 | 1322 | 490 | MQ ME | 420 468 | 500 a 525 |
31CrMoV9 | 1367 | 507 | |||
32CDV13 | 1500 | 550 |