Bridge Crane Design Calculation

Bridge Crane for Foundry 130/30t-22.5m A8 Design Calculation

I. The outline of Design Calculation

The thread as follows:

Hook parameter is determined based on the rated lifting capacity;

According to the dead load of hook and max lifting height from rated lifting capacity to determine the motor model, pulley diameter, rope diameter, roll diameter, wall thickness, reducer Model and brake models;

According to user’s requirements on hook limit position to determine the layout of the trolley;

Estimate the trolley dead load and maximum wheel load to determine the number of trolley wheels and wheel diameter, and with the rated lifting capacity to determine the main beam section size;

Estimate the total weight of the crane, and estimates crane maximum wheel according to lift and right limit position of hook;

To determine the diameter of wheel, checking the trolley running motor power, and determine the reducer and brake model according to maximum wheel pressure;

Determine the size of the key components of the crane balanced arm and axle;

II. General Requirement and Known Parameters of the crane

Capacity: Main Hoist Q1=130000kg

Aux. Hoist Q2=30000kg

Span:19m

Lifting Speed: Main Hoist VMH=0.46~4.6m/min

Aux. Hoist VAH=1.2~12m/min

Cross Travel?VCT=1.91~19.1m/min

Long Travel? VLT=7.8~78 m/min

Lifting Height: Main Hoist 20.5m?Aux. Hoist 22.5m

Max. wheel load:?595Kn

Max. Height of the crane:4400mm

Max. Width of the crane:14300mm

Hook Approaches: Aux Hoist Cabin end 1550mm

Main Hoist Opp. End 2300mm

Crane Work Duty?A8 Mechanism Work Duty?M8

Unit as follows if no specified in the design calculation:

Force, Weight: N?Kg

Length: mm

Time: min

Stress: MPa

Moment (Torque)?N.m

• Calculation content and procedures

1 Calculation:

1.1 Cabin follow the original series, considered as independent components in the machine, so it is not regarded in this design calculation manual.

1.2 Walking platform and railings are all made in accordance with the relevant national standards, ministerial standard, so it is not regarded in this design calculation.

1.3 Gear Couplings provided by qualified subcontractor with long-term cooperation, so it is not regarded in this design calculation.

2?Calculation Process and The Results:

2.1 Main Hoist Mechanism

2.1.1 Motor Selection?

Static Power:

Nj=(QH+G0)×V/102/60/m/?

Where:

QH --Capacity?130000Kg

G0—Hook Weight?14000Kg

V—Lifting Speed?4.6m/min

?-- Gross Efficiency?0.85

m—No.s of motors

Nj=63.67Kw

Calculation Power?

Ne=Kd×Nj

Where?

Kd-- coefficient?1.1

Ne=70.03Kw

Primary motor?QABP315S6A?2×75Kw?

b?Motor overload checkout

Motor power rating when benchmark duty PN?H×Nj /?T

H?coefficient?H=2.2

?T:when benchmark cyclic duration factor, allowed motor overload multiple,?T=3.0

=H×Nj/?T=51.36kw

Single motor QABP315S6A power rating when benchmark duty is 75kw?

So motor QABP315S6A meets the requirements.

2.1.2 Wire rope calculation:

Capacity QH?130t

Work duty?M8

Pulley Ratio m?2×4

Factor of Safety n?9

Pulley Efficiency??0.97

Wire rope Calculation tension :

Smax= QH×9.81×1000/2/m/?/2=92.84kN

Allowed breaking force of wire rope?

S=n×Smax=835.56kN

Wire rope selected: 36NAT-6×36WS+IWR1870,its nominal tension 863[KN]?is greater than Max. breaking force. So 30NAT-6×19WS+IWR1870 meets the requirement?

Then we can get Groove pitch of drum t=40mm?

2.1.3 Drum parameter calculation, Strength calculation and stability calculation.

Calculation results?

1.Structure of drum

Dia. Of wire rope d=36 mm

Dia. Of drum D= 800 mm

The standard of groove shape: International standard.

Groove Pitch p= 40 mm

The length of drum with groove L0?

L0 =H*m/?/D0*p+z1*p

Where?

H—Lifting height=20.5m

m— Pulley Ratio =4

D0— Calculation dia. of drum =D+d=836 mm

z1—Safety loop: 3

L0 = 1368.87 mm

Number of groove(inclusive safety loop)=34.22

Total length of drum L?

L =2*(L0+L1+L2)+Lg

Where?

L1-- front end length=p=111 mm

L2—length of groove for fixing wire rope=3p=102 mm

Lg—length of middle drum without groove=100 mm

L = 3263.74 mm

Set L=3300mm

Drum plate thickness and checkout:

Plate thickness t=22 mm

Material?Q345B

Yield strength of the material??s=325 MPa

2. Pressure stress of drum checkout:

Pressure stress of drum plate?1=106.98 MPa

Safety factor of the drum strength n=?s/?1=3.04

For safety factor of plate, n should be greater than or equal to 2.

*So, meet the requirement.*

3. Drum stability checkout:

When dia. of drum D>1200mm,or length of drum L>2D,we should check drum stability.

P=5.8MPa

Stability unit pressure stress of drum plate P0=18.49 MPa

Stability coefficient k= P0 /P=3.19

For safety factor of plate n should be greater than or equal to 1.3.

• So, meet the requirement. *

2.1.4 Selecting calculation of gearbox and brake

Selection of hoist gearbox?

Rotating speed of drum:

nj=V×bi/?/D0

Where?

V—Lifting speed?4.6m/min

bi—Pulley ratio?4

D0—Effective dia. of drum

D0?dia. of drum?dia. of wire rope?0.836m

nj=7.01r/min

Computing torque of drum?

T=(Q+G0)/bi×D0/2×1.1

In the caculation?

Q—Capacity?130000Kg

G0—Hook weight?14000Kg

T=165528N.m

Calculation Power of gearbox?

Nj= 2xNe= 140.07Kw

Gear ratio of gearbox?

i=nd/nj

Where?

nd- Rotating speed of motor?990r/min

i=141.23

Actual lifting speed?

V'=V×i0/i0'=4.64

Where?

V—Lifting speed?4.6m/min

i0-Calculation ratio?141.23

i0'-Actual ratio?140

Gearbox is non-standard designed?Ratio designed 140?Allowed input power designed of high-speed shaft of gearbox should be greater or equal to 140 kW?

a? Selection of brake

The plan is: 4 brakes mounted on the double side input pinion shaft of the gearbox.

The minimum braking Torque of unit brake?

Mz=Kz×(Q+G0)×D0/2/bi/i×?=1316.7N.m

Where?

Kz—Safety factor of braking?1.25

bi—Pulley ratio?4

D0—Actual dia. of drum 0.836m

D0?(Dia. of drum?Dia. of wire rope)

??Transmission efficiency of the mechanism?0.98

According to the brake catalogue YWZ9-500/E121S is selected?The rating braking torque M=2500N.m> Mz?So the brake meets requirement.

2.2 Aux. Hoist Mechanism

Calculation method and process are same to main hoist mechanism. Ignore the process?results as follows?

Motor?QABP315S6A

Gearbox?QY3D400-45

Brake?YWZ9-400/E80?double?

Wire rope?20NAT-6×19W+IWR1870

Dia. of drum??650mm

Pulley ratio?4

2.3 Cross travelling mechanism

The plan is: 4 wheels, two active wheels are driven by two mechanisms via coupling. Dia. of trolley wheel dCT=700mm?

2.3.1 Selection of motor

Friction torque?

Mm=(Q+Gxc)(k+?×d/2)?=10197N.m

Wherer?

Q --Capacity?130000Kg

Gxc-Trolley weight?76000Kg

k - Coefficient of rolling friction?0.0008

?- Bearing friction coefficient?0.02

d - Bearing bore diameter?0.1675m

?- additional resistance coefficient?2

Travelling friction resistance?

Pm=2×Mm/Dc=29134.29N.m

Where?

Dc –Dia. of wheel?0.7m

Motor static power?

Nj=Pm×Vxc/1000/60/?/m=5.15Kw

Where?

Vxc –Speed of cross travel?19.1m/min

?- Transmission efficiency of the mechanism =0.9

m-Number of driven motors?2 sets

Motor power?

N=kd×Nj=7.21Kw

Where?

kd - Increase coefficient of power?1.4

Motor selection?QABP160M6A?Ne=7.5Kw

2.3.2 Selecting calculation of gearbox

Rotating speed of wheel?

nc=Vc/?/Dc=8.69r/min

Where?

Vc—Traveling speed?19.1m/min

Dc—Dia. of wheel =0.7m

Gear ratio of gearbox:

i0=nd/nc=112.2

Where?

nd-Rotating speed of motor?975r/min

Actual travelling speed?

V'=Vc×i0/i0'=19.13m/min

Where?

i0-- Calculation ratio?112.2

i0'-- Actual ratio?112

According to the gearbox catalogue QY4S250L-112 is selected. Allowed input power of high-speed shaft of the gearbox for M7-duty P=12.8kw> N=7.21kw?so meet the requirement?

2.4 Long travelling mechanism

The plan is: 4 corner drive, motors, gearboxes and brakes be set inside of main girder, low speed shaft of gearbox be connected with wheels via universal coupling.

Calculation method and process are same to cross travelling mechanism. Ignore the process?results as follows?

Motor?QABP200L6B

Gearbox?QY3D250-31.5

Brake?YWZ4-300/E50

Dia. of wheel?800mm

Bearing bore diameter of LT wheel?210mm

2.5 Bridge

2.5.1 Calculation of main girder

Calculating load and parameter of main girder as follow:

1. 1. Middle section features

b1= 1456.5 mm, b2= 1700 mm

b3= 1600 mm, d1= 12 mm

d2= 12 mm, d3= 8 mm

d4= 10 mm, d5= 43.5 mm

d6= 42 mm, h= 2200 mm

b4= 400 mm?t1= 21 mm

h1= 174 mm, t2= 13 mm

Height and thickness of web plate of girder end:

hd= 800 mm

dd3= 16 mm, dd4= 16 mm

Area?

s1= 86400 mm^2

ox= 700.12 mm, oy= 1023.32 mm

Flexural center?

ex= 710.11 mm, ey= 1100 mm

Moment of inertia?

ix= 72694407470 mm^4

iy= 38953130734 mm^4

Section modulus in bending?

(Point upright)?

wx1= 69609321.82 mm^3

wy1= 42965223.52 mm^3

(Point lower right)?

wx2= 61155574.18 mm^3

wy2= 51929199.31 mm^3

(Point upleft)?

wx3= 70214433.18 mm^3

wy3= 41008475.32 mm^3

(Point lower left)?

wx4= 61155574.18 mm^3

wy4= 41008475.32 mm^3

Static moment of inertia to neutral axis?

(Part of upright)

sx1= 17564468.51 mm^3

(Part of up left)

sx2= 14799303.49 mm^3

(Part of lower right)

sx3= 17568701.95 mm^3

(Part of lower left)

sx4= 15921501.27 mm^3

2. Girder end section features

Area?

s1= 71356 mm^2

Centroid?

ox2= 746.03 mm, oy2= 370.59 mm

Moment of inertia?

ix2= 8911070379 mm^4

iy2= 29925917434 mm^4

Static moment of inertia to neutral axis?

(Part of upright)

ssx1= 4920178.21 mm^3

(Point upleft)

ssx2= 4402393.79 mm^3

(Point lower right)

ssx3= 5592537.51 mm^3

(Part of lower left)

ssx4= 5219960.78 mm^3

3. Design load of girder

Bending moment due to self-weight of girder?

m1=qzl*l*l/8= 622350000 N.mm

Bending moment due to self-weight of plateform?

m2=qzt*l*l/8= 0 N.mm

Bending moment due to wheel load?

m3= 4708000000 N.mm

Bending moment due to drive mechanism?

m4= 250000000 N.mm

Bending moment due to the load of cabin?

m5= 9000000 N.mm

Total vertical bending moment?

mz=m1+m2+m3+m4+m5= 5589350000 N.mm

Horizontal bending moment due to inertial load?

mg= 558935000 N.mm

4. Stress of middle section in girder

Normal stress of point (1)?

?1= 93.31 Mpa

Normal stress of point (2)?

?2= 102.16 Mpa

Normal stress of point (3)?

?3= 93.23 Mpa

Normal stress of point (4)?

?4= 105.03 Mpa

Normal stress of point (5)?

?5= 103.55 Mpa 2.5.2 End beam intensity calculation:

This crane adopts four corners driving, the supporting point is in the end of the main beam, so the end beams substantially only affected by the crane lateral skew couple formed by the load in the actual work, and since by the main beam end portion constraints, end beams often taken and the same cross-section of the cross-section of the main beam ends in the production, the cross-sectional size is large, so the end beam is not regarded in this calculation book.

• Conclusion

According to the above calculation instructions:

1. The initial parameters meet the crane requirements.
2. The structural design of this crane is reliable and able to meet the requirements of the customer on rated lifting capacity, speed, and working life.
3. Design of this crane according with the "design specifications requirements of GB3811-2008".

• Main References

1. Crane Design Manual", China Railway Press
2. The metal structure" edited by Xu Kening, Machinery Industry Press
3. Mechanical Design Handbook", edited by Cheng Daxian, Chemical Industry Press

4."Mechanics of Materials", edited by Liu Wenhong, Higher Education Presswww.craneus.com

Overhead Crane @ www.craneus.com