canales moreno isidro fermin
TRANSCRIPT
MACHINE ELEMENTS
YEAR PROJECTMACHINE ELEMENTS IIStudent name: CANALES MORENO Isidro Fermin
Year: IIISpecialization: Mechanical Engineering
Transilvania UNIVERSITY OF BRASOV
1. STRUCURAL SCHEME, TORQUES AND ROTATION FOR EACH SHAFT
1.2 Structural scheme
Fig 1
1.2 Torque and rotations for each shaft
Engine
n = 1470 rot/min
Mt = 9.55*
Input shaft (I)
nI = n /iL= 1470 / 1.75 = 840 rot/min
TI = Mt * iL = 1011889.578 N*mm
Output shaft (II)
nII =
TII = TI * ir 1011889.578 *4.5=4.55475.95 N*mm
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P, nMt
2. PROJECT PARAMETERS
2. INPUT DATA2.1 Pinion speed n1, rot/min n1 = 840 rot/min2.2 The torsion torque at the pinion of the gearing T1, N*mm
T1 = 1011889.578 N*mm
2.3 Gearing ratio udat udat = 4.52.4 Minimum functioning time of the gearing Lh, hours
Lh = 10000 hours
2.5 Functioning conditions of the gearing
Driver machine: electrical motorDriven machine: fansType of load: uniform
2.6 The loading cycles for the teeth
contact load : pulsatory cyclebending load : pulsatory cycle
2.7 Number of load cycles of the tooth flank, at a full rotation 1 for the pinion, 2
for the driven wheel
1,2 = 1
2.8 The reference rack profile
For inclined teeth n = 200; h*
an = 1,0; c*u = 0.25;
*fn = 0.38
3. CHOOSING THE MATERIALS, HEAT TREATMENTS AND THE LIMIT STRESSES 3.1 Choosing materials and treatments
We choose 17CrNi16 from STAS 791Treatment Ce+C+rHardness - external 60 HRC - internal 400 HBr = 1000 MPa02 = 635 MPa
3.2 Limit stresses, Hlim1,2, at contact and Flim1,2 at bending, MPa
Hlim1,2 = 1500 MPaFlim1,2 = 500 MPa
4. PRE-DIMENSIONING CALCULUS
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4.1 Number of teeth z1, of the pinion, respectively z2 of the driven wheel.
it is choosen z1=14
it is choosen z2 = 63
4.2 Real gearing ratio u
4.3 The contact calculus factors [21,60]4.3.1 The elasticity factor of the wheels material zE,
4.3.2 The contact area factor zH
4.3.3 The covering factor z
4.3.4 Inclining factor of the teeth z
4.4 The factor for the bending calculus4.4.1 Number of teeth for the equivalent wheels
4.4.2 The displacement coefficient of the profile in the normal plane xn1,2
4.4.3 Shape factor of the teeth YFa 1,2
YFa1 = YFa1(zn1,xn1) = YFa1(16.581,0) = 3.55YFa2 = YFa2(zn2,xn2) = YFa2(74.657,0) = 2.25
4.4.4 Correction factor of stress YSa1 = YSa1(zn1,xn1) = YSa1(16.581,0) = 1.45
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YSa 1,2 YSa2 = YSa2(zn2,xn2) = YSa2(74.657,0) = 1.75
4.4.5 Covering factor Y
4.4.6 Inclined factor for the teeth Y
4.5 Load correction factor4.5.1 The functioning regime factor ka
kA = 1.10
4.5.2 Dynamic factor kv kv = 1.084.5.3 Distribution (uneven) factor for load on the width of the teeth kH for contact and kF
for bending
kH = 1.5kF = 1.5
4.5.4 The uneven distribution factor of the frontal plane kH at contact and kF for bending 4.6 The allowable resistances HP1,2 at contact and FP1,2 for bending [MPa]
4.7 The distance between the axis at pre-dimensioning 4.7.1 Wide coefficient a, d
a =0.25
d =
4.7.2 Distance between the axis from the
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strength condition at contact awH, mm4.7.3 Distance between axis from the strength condition at bending awF, mm
4.7.4 Adopting the distance between the axis at predimensioning aw, mm
aw = max (awH,awF) = max (269.13,173.56) = 269.13mm ;We adopt from STAS 6057 the following aw = 275 mm
5. GEARING FORCES CALCULUS
5.1 Forces calculus
5.1.1 Tangential force Ft, N;
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5.1.2 Radial force Fr, N;
5.1.3 Axial force Fa, N;
5.2 Choosing the sense of rotation and applying forces
Fig. 5
6. CALCULUS OF THE SHAFTS
6.1 Pre-dimensioning calculus:
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6.2 Choose of bearing mounting for input and output shafts:
d(b)I,II = dI,II – (2…8)mm
Shaft D(db) D B a Cr X Y Symbol Cr
I 35 72 17 31 28.5 0.35 0.57 7207BII 50 90 20 39 37.4 0.35 0.57 7210B
6.3 Check of the input shaft for composed stresses.
6.3.1 Horizontal plane
Fig. 6.1
6.3.2 Vertical plane
A B
RAH RBH
Fr1
Fa1
[H]
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Fig. 6.2
6.4 Determining of the reactions in the 2 bearings
Fig. 6.3
6.5 Stresses identification
9.6.1 Torsion
RAV
l1
A B
RBV
Ft1
[V]
l1
AB
Mih
Miv
Mt
T
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9.6.2 Bending
6.6 Equivalent stress
7. CHOOSING AND CALCULUS OF THE PARALLEL KEY
Fig. 7.1
we choose from STAS 1004-81: b=16; h=10
From crushing σs= , σas=120MPa,
l = lc + b = 136 + 16 = 152 we modify by our design l = 63 mm.d b h
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I 28 8 7II 44 14 9
II’ 50 16 10 7.1 CHOOSING THE ENDS OF THE SHAFTS
Fig. 7.2
Input shaft:daI = dsI – (3…5) mm = 32 - 3 = 32 mmWe choose from STAS 8724/2-71; l = 58
Output shaft:daII = dsII – (3…5) mm = 48 - 3 = 39 mm
8. CHECKING THE ASSEMBLY WITH THE BALL-BEARINGS AFTER THE DYNAMIC LOAD CAPACITY
Fig. 8
da lI 28 42II 44 54
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RAH RBH
8.1 Establishing the supplementary axial forces
8.2 Establishing axial forces in the bearings:
Bearing A- establishing axial forces in the bearings
the ball-bearing is found in the 1st area
where we can neglect the influence of the axial force over the equivalent dynamic load.
- Equivalent dynamic load
where V=1- Durability of the bearing
- Dynamic capacity load
- Durability ensured by the ball bearing
- Ensured functioning time
9&10. CHOOSING AND JUSTIFYUING THE OILING SYSTEM AND SEALING SYSTEM
Oiling the gearings:
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Gears of gears are lubricated by oil bath bubbling. InTo this end a gear wheel is inserted into the oil pan upthe height of a tooth but at least 10 mm and never exceeding 6 timesmodule.If multi-stage gear units (when the wheels do not reachbath), the anointing is done by means of gears of stray ortablespoons discs or spraying.Lubrication of the gears balbotare apply to working regularlywith speeds of up to 15 m / s. May Maire peripheral speeds, lubrication isrun oil injectors. Oil pressure is usually 0.1-At 0.8.To grease commonly used mineral oil viscosity 3-60degrees ^ C E50As the peripheral speed is lower, and even contact pressureroughness is higher, the more they use thicker oils.The multi-stage gearboxes, lubrication oil is chosen with aviscosity corresponding to step forward greatest moment.For the volume of oil bath oil is considered a horse 0.25-0.5 lpower. Oil change period is 1000-5000 hoursoperation (if it is sealed and the oil is angrenajufiltered after every 2500 hours). Filtering canuse magnetic filters. On reducing new oil change after 200 -300 hours of operation.
9.1 Oiling the ball-bearings.
Choose rulemnti lubricants for bearings with lubrication intervals and determination ismade depending on the size, speed, load and temperature of the bearing.In general, liquid lubricants, to those consistent with a number of advantages such ashigher physical and chemical stability, speed and ability to use high temperatures andvery low temperatures ola, easier removal of heat that can occur in camp, oppositelower resistance in rolling bodies. As disadvantages can be mentioned: the difficultsealing camp, while losses through leaks, etc..Lubrication with grease is advantageous as it leads to constructions limped tobearings, seals easier and lower cost, better protection from external agents rulemtilor,smaller loss of lubricant, etc..In the case of liquid lubrication, for small shi average speed, oil level should reachapproximately to the center of ball or roller rulementului lower.In normal operating conditions are used for lubricating waxes. The amount of greaselubrication of a bearing frame rulemnti required generally depends on the shaft speed.11. DESIGN OF CHAIN DRIVE
11.1 NUMBER OF TEETH OF THE SMALL WHELL
11.2 NUMBER OF TEETH OF THE BIG WHELL
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11.3 THE PITCH
from STAS 5174-66
11.4 THE AVARAGE SPEED
11.5 THE ADMISIBLE USEFULL FORCE
11.6 THE ADMISIBLE USEFUL POWER
the number of chain rows
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We choose p=p2=15.875 mm
11.7 THE PRELIMINARY DISTANCE BETWEEN THE AXIS
11.8 THE NUMBER OF LINKS
11.9 THE LENGTH OF THE CHAIN
11.10 THE RECALCULATED DISTANCE BETWEEN THE AXIS
11.11 THE FORCE FROM THE PASSIVE BRANCH OF THE CHAIN
from STAS 5174-66
P1 P2 P3
Zr 4 2 2
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11.12 THE USEFULL FORCE
11.13 THE FORCE FROM THE ACTIVE BRANCH OF THE CHAIN
11.14 THE SAFETY COFFICIENT AT BREAKING
from STAS 5174-66
11.15 THE FORCE THAT ACTS ON THE SHAFTS
12. Choosing the materials and manufacturing system
Materials used in construction reducersBuilding Materials gears: steelsSteels are used to improve the otelutrile carbon steels with 0.4-0.6% C and 0.35-0.45% C low alloy Mn, Cr, Cr-Mo, Cr, Ni etc. Unalloyed and low alloy steels, Cr, Cr =Mo, Cr-Ni, a possible cyanide
IronsIrons are used to slow functioning gears, wheels rarely work exchange, etc.. Whensilence is required severe conditions may be used ordinary gray cast iron withspheroidal graphite.
Materials used for the execution tree:In general, trees that are not heat treated carbon steel is made from ordinary: OL 50,OL 60, 500-78 StasIndifferent trees bearing capacity can use high quality carbon steel: XC 35, XC 45,XC 60, according to STAS 880-66.If trees are required to ask pternic small chrome alloy steels are used, Cr or Cr-Mn-Ni
Materials used for the execution of carcassesCarcasses, because rigidity is the dominant criterion, are made of cast iron or cast steel. Most carcasses are made by casting iron medium strength FC 200, FC 250.
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Technical safety regulations
La locul sau in exploatarea reductoarelor va trebui sa se tina seama de urmatoarele prevederi cu privire la normele de tehnica securitatii muncii:
The operation of reduction gears in place will have to take account of these provisionson work safety technical rules: Reducer to be securely bolted to the workbench Do not use gears lacking parts (parts of housing, eteansare caps etc) Will not change the oil during operation Will not check the oil level during operation Will replace defective parts with other corespuzatoare
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