SPUR GEAR DESIGN Contents 9.1 Problem 1 Analysis 9.2 Problem 2 Spur gear 9.1 PROBLEM 1 – SPUR GEAR DESIGN In a conveyor system a step-down gear drive is used. The input pinion is made of 18 eeth, 2.5 mm module, 20o full depth teeth of hardness 330Bhn and runs at 1720 pm. The driven gear is of hardness 280Bhn and runs with moderate shock at 860 pm. Face width of wheels is 35 mm. The gears are supported on less rigid ountings, less accurate gears and contact across full face may be assumed. The ultimate tensile strength of pinion and gear materials is 420 and 385MPa respectively. The gears are made by hobbing process. Find the tooth bending strength of both wheels and the maximum power that can be transmitted by the drive with a factor of safety 1.5. The layout diagram is shown in
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Transcript
SPUR GEAR DESIGN
Contents
9.1 Problem 1 Analysis
9.2 Problem 2 Spur gear
9.1 PROBLEM 1 – SPUR GEAR DESIGN
In a conveyor system a step-down gear drive is used. The input pinion is
made of 18 eeth, 2.5 mm module, 20o full depth teeth of hardness 330Bhn and runs
at 1720 pm. The driven gear is of hardness 280Bhn and runs with moderate shock
at 860 pm. Face width of wheels is 35 mm. The gears are supported on less rigid
ountings, less accurate gears and contact across full face may be assumed. The
ultimate tensile strength of pinion and gear materials is 420 and 385MPa
respectively. The gears are made by hobbing process. Find the tooth bending
strength of both wheels and the maximum power that can be transmitted by the
drive with a factor of safety 1.5. The layout diagram is shown in
The bending fatigue stress is found from AGMA equation as,
We know that,
Substituting values from table 1,
Data given for gear and pinion
Using the values from
V = π dn/60000 = π x 45 x 1720/60000
= 4.051m/s
We know that
J values for pinion and gear
The J value is obtained from Fig. 9.2 for sharing teeth as in practice. Ko and Km
values are obtained from Tables 9.3 and 9.4 for the given conditions.