Table of contents Chapter 1: Selecting electric motor and speed ratio distriDUtiON.... 19 CHAPTER 4: PRELIMINARY DESIGN SHAFT AND BEARING SELECTION.... 300 days of working per year, 8 ho
Necessary power and rate of revolution of the el€cfrIC ImOOT S1 1 11212111111111121111 1110111111 01 1E He, 8 5 Calculate equivalent revolution Of MOOD ccc ene en en etn ec ec ene ctecteceeeeteeteeteneeeteeetietesteeneentes 8 6 Selecting electric MOO ằằằ
5 Calculate equivalent revolution of motor
Speed ratio of the system: u,.72
Selecting proper motor that satisfies
Nin Nequivalent = 1461.78 rpm Choose the below motor
+ e€ Power revolution Ị n% M,, Mùa, Monin of motor f
Speed ratio of the system u,= n motor = 1460 = 10.71
Second shaft (coupling — spur gear)
P,= The * Ne 0.995x0.98 =————=7.|k 69 (kW) first shaft (spur gear — belt)
Pyyy=P„=—— = = 8.52 (kW mà "Dy XN, 0.995 * 0.95 (kW)
9 Rate of revolution of each shaft
First shaft (spur gear — belt) nụ = 1460 (rpm) n= nt = 1460 — 730 rpm) n
Up 2 Second shaft (coupling — spur gear) n;_ 730
Second shaft (bevel gear — belt)
T,=9.55 x10”x P 9.55 x10 730 105311.64 (Nmm) Third shaft (coupling — bevel gear)
Motor First shaft | Second shaft
Rate of revolution (rpm) 1460 730 136.19 transmission ratio 2 5.36
1 Select belt type b be h ° A Length T dimin
Belt | Symbol y 5 Ộ Ộ mm | mm | mm | mm | mm? mm Nm mm
By standard, we choose d; = 160 mm
4 Calculate diameter of big pulley
Pitch diameter of large sheave with slip efficiency €=0.02 d,=ud,|1—‡]=2 x 160 x |1—0.02)13.6 |mm_
According to the below table u 1 2 3 4 5 >6 a 15d, 1.2đ, đ, 0.95đ, 0.9đ, 0.85đ,
6 Pitch length m(do+di) (do-di) _., 4.3794 1 (315+160) , (315-160)
Accuracy Center to Center Distance
9 Width and outside parameter of pulleys
Outside parameter of small pulley: đạ¡=d,+2h,0+2 x5.71.4(mm)
Outside parameter of big pulley: dạ¿=d,+2h,15+2 x5.726.4(mm)
Static tension on each belt:
Force on input and output
Oma =A *Zq tPV X10 + BS ae + 55138 +1200 x 12.23”x10°+ 160 x 100=9.95|Mpa}F 32> The calculation is to select the bearing at D section
We have the highest ratio F, 2611.68 with bore diameter d= 55mm for the given shaft
=0.17 on shaft II = select single-row deep groove ball bearing
- Define factors V,K,,K, and calculate dynamic equivalent force Q
As the bearing has no axial load X=1^ Y =0
- Calculate working life and dynamic load factor
Working live in million revolutions:
- _ Select bearing size satisfying C„R,,11.08N
In conclusion, B is the most dangerous section h Determine shaflt diameter at dangerous section:
By standard we choose dgUmm i Diagram of shaft IT j- Check section for bearing
By standard we choose d,Pmm k Check section for elastic coupling
By standard we choose d,Emm
1 Design the key on shaft
- Base on shaft diameter to choose key parameter for gear:
Parameter of key section: b = 16mm; h = 10mm
Radius of trench angle r: min: 0.25; max: 0.4
- Base on shaft diameter to choose key parameter for coupling:
Parameter of key section: b = 14mm; h = 9mm
Radius of trench angle r: min: 0.25; max: 0.4
6 CHECKING FATIGUE ENDURANCE: a For Shaft I
Magnitude and mean values of bending stress:
32 2d; 32 2:35 ơ„=0 Magnitude and mean values of torsion stress (for one-way rotation):
Because there is a keyseat at section B, select) , _, 9 (according to Table 16)
0.81 (according to Table 17) Becaused,5mm, select c—
Because the shaft is grinded without any specific additional hardening method, select B=1
Safety factors regarding to bending and torsion stresses: Ơ_¡ _ 350
Safety factors due to fatigue life:
~> Shaft I satisfied fatigue condition b For Shaft IT
Critical position on shaft I is at C with d-.0mm, according to Table 15
~ Select a feather key with bmm ;h= 8mm;t=5 mm ;t,—=3.3mm
Magnitude and mean values of bending stress:
MÔ ndị beldy-CF at _14-55.50-55" MP
32 2d 32 2-50 ơ„=0 m Magnitude and mean values of torsion stress (for one-way rotation):
Fatigue limits of material: ơ_,=|0.4+0.5 Jơ,=|0.4+ 0.5) 75000 + 375 | MPd]
Because there is a keyseat at section B, select K
„=0 81 Because d,P mm, select © -0.76 (according to Table 17)
Because the shaft is grinded without any specific additional hardening method, select B=1
Safety factors regarding to bending and torsion stresses:
Safety factors due to fatigue life:
— Shaft LÍ satisfied fatigue condition
Operating conditions: one-direction working, light-impact loading, 2-shift operation (8 hours/shift) and
- Determine radial and axial loads on bearings, select bearing type
Radial force on the bearing at A section:
Radial force on the bearing at C section:
Because F,A>F,c The calculation is to select the bearing at A section
We have the highest ratio == 5085 bearing with bore diameter d= 35mm for the given shaft
0.22 XY=0
- Calculate working life and dynamic load factor
Working live in million revolutions:
Select bearing size satisfying C„