Slide Mechanics Machine

8/4/2019 Slide Mechanics Machine

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Balancing of rotating equipment is a very important

aspect of the design and operation of any mechanical

system that involves a rotating shaft.

Rotating systems are rarely perfectly balanced; the

degree of balance required depends upon the size and

location of the unbalances and the speed ofoperation.

Unbalance is generally caused by an unbalanced mass,

located at some eccentricity, spinning about thecenter of rotation at a constant frequency.


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Static balancing refers to a procedure that adds orsubtracts mass at some eccentricity to balance the

vector forces.

Dynamic balancing refers to a procedure that addsor subtracts mass at some eccentricity and location

along the axis of rotation to balance the unbalance

moments.


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Explain the importance of balancing

Explain static and dynamic balance

Solve problems involving in single plane

Solve problem using static balance

Use vector to solve problems


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In this project, we need to statically balance the fan

system.

The fan is unbalance and it makes the fan vibration.

In this situation the mass and the radian for A,B,C

are given.

So we need to determine the mass and the radian

for D so it can be balance and no vibration.

To solve this problem, we use static balance

equation.


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Balancing In One Plane

System is a simple disc then static balance is all that is needed

A thin disc or wheel on which the centre of gravity is not the

same as the centre of rotation


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Placing a suitable mass at a suitable radius to make the system balance.

The centrifugal force acting on each mass is F = M r

F1= M1r1 F2 = M2r2

F3 = M3r3


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The balancing mass M4 is then added at a suitable

raduis and angle such that the product Mr is correct


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The result obtained would be the same whatever the

value of W and when W = 0 we have static balance

Note that angles will be given in normalmathematical terms with anticlockwise with being

positive from the x axis as shown


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Three masses A, B, and C are placed on a balancedfan as shown at radii of 120mm, 100mm and 80mm

respectively, The masses are 1 gram, 0.5 gram and

0.7gram respectively. Find the 4th mass which should

be added at a radius of 60mm in order to staticallybalance the system


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Unbalance Fan


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Unbalance Fan


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Solution:-

Given:-

Mass A = 1 gram Radius A = 120mmMass B = 0.5 gram Radius B = 100mm

Mass C = 0.7 gram Radius C = 80mm

Radius D = 60mm

First draw up a table to calculate the value of M and r for each mass.

Plane Mass,m(g) Radii,r(mm) Mr(gmm) Direction,0

A 1 120 120 0

B 0.5 100 50 30

C 0.7 80 56 100

D mD 60 60mD D


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Draw the Mr polygon to find the value of Mr for the 4th mass.


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Equation:

Thus, 60MD = 143 gmmMD = 143/60

MD = 2.4 gmm

So,t he mass required is 2.4 gmm and 2080 anticlockwise of A as shown.


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Balance Fan


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Balancing is important to avoid vibrations .For example, fan

when a rotating body is unbalance, it will apply stress on the

bearing and other parts on the bodies.

Two types of balancing:

Static balance

mr = 0 that is m1r1+m2r2+m3r3 = 0Dynamic balance

mWrl = 0 that is m1Wr1l1 + m2Wr2l2 + m3Wr3l3 = 0

We choose static balance solution because by body is located

on a single plane only, where m1, m2 and m3.., are the

unbalanced masses and r1,r2,r3rn are the radius from the

centre of rotation respective.


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When unbalance has been identified and quantified, the

correction is straight forward.

Weight has to be either added or removed from the rotatingelement.

Rotates needs to be in a state of balance to ensure smooth

running when in operation.

Effects of unbalance become more detrimental.

Modern technology allows for accurate balancing to be

performed.

Increased time between outages and availability for production is

the prime benefit.

Vibration waste more energy to rotating element.

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Slide Mechanics Machine