2.2 Objectives of

present work

1.

TO generate Numerical

finite element models to investigate the structural and dynamic behavior of a

vibrating screen.

2.

To study the stress

distribution on the vibrating box and vibrating frame under current operating

condition.

3.

To study the stress

concentration on the vibrating box and vibrating frame under current operating

condition.

4.

Resonable selection of

vibrating screen working frequency.

Chapter 3

Working Conditions Of Inline Knockout Machine

The unit consists of the freely suspended screen and a

shaft assembly carried by the box. Near each end of the shaft, an eccentric

portion is turned. The shaft is counterbalanced, by weighted fly-wheels,

against the weight of the screen and loads that may be superimposed on it. When

the shaft rotates, eccentric motion is transmitted from the eccentric portions,

through the two bearings, to the screen frame.

Frame

is mounted on vibrating box with the help of two steel angels. Two L shaped

angular plates restricts the motion on screen. The vibrations are transferred

from torsion bars to screen.

Spring dampers are mounted as per the load to

be applied on the vibrating screen, two on each side for damping purpose and

grounded.

Property

Specification(mm)

Wire diameter

19

Inner diameter

90

Outer diameter

128

Length

315

Pitch

39.37

Number of

turns

8

stiffness

120.94 N/mm^2

*

Table 3.1-Properties Of Spring

Damper

Stiffness values of spring is

calculated by using above property and used in the modal analysis as one of the

input value. Damping factor is also one of the property to be used in harmonic

analysis.

Stiffness of spring calculation –

1.?=8pd^3N/gd^4

=8*39200*(109)^3*8/76920*19^4

=324.109mm

2.k=p/ ?

=39200/324.109

=120.94 N/mm^2

CHAPTER 4

Modeling

Of The Component

_____________________________________________________

For the failure analysis of the knockout machine the main

components to be considered are vibrating box and vibrating screen. During the

cycle of process effect of vibration is mainly observed on the side plate of

the box, secondly the vibrating screen also suffers failure as result of

frequent loading of mold boxes.

The vibrating box is divided into two parts: Vibrating

frame and screen frame. Screen is installed in the interior of screen frame.

The box is located on the vibration damper using springs. Material enters into

the upper ports of vibrating box and is discharged through the bottom ports

during the working.

Because of the complex of structure and too many parts of

screen and screen frame, the finite element models of them are very difficult

to be building by using the ANSYS. Because CAD is mature and operational

software, it can quickly create virtual models of screen and screen frame.

Therefore, the combination of CAD and ANSYS is very necessary for analyzing

vibrating screen. The combination can improve the speed of changing model and

the efficiency of analyzing vibrating screen .The CAD model was changed into a

standard format which can is imported into ANSYS in order to get finite element

model.

CATIA allows the creation of 3D areas, from 3D images,

sheet metal, compounds, shaped, made or pedaling areas up to the meaning of

technical devices. The application provides advanced technological innovation

for technical appearance. It provides tools to complete product meaning, such

as functional specifications as well as kinematics meaning. CATIA provides an

extensive variety of applications. CATIA v5 is able to read and produce STEP

format files for reverse technological innovation and surface recycling.

For

the analysis purpose following 2 components is considered:-

1.

Vibrating box

2. Vibrating screen

1.

Vibrating Box-

Vibrating box is main

component of inline knockout machine which supports all other components such

as frame, dampers ,torsion bar, angle plates etc. generally the box is

combination of welding and bending process. Torsion bar is mounted by bolting a

circular plate inside the box plate. The screen is mounted with the help of

angle plate.one net like structure is present at the top of screen but is not

considered in analysis.

Fig 4.1.1-Isometric View Of Inline knockout Machine

Fig 4.1.2- Detailed Drawing Of Vibrating Box

2.

Vibrating Frame-

Vibrating

screen is the second part under consideration for analysis. Function of the

screen is to support vibrating net. Mold boxes and castings passes over this

net. Vibrating screen act as a support for the vibrating box and does not allow

them to scatter over the surface.

Fig 4.1.2-

Detailed Drawing Of Vibrating Screen

CHAPTER

5

ANALYSIS OF THE COMPONENTS

_____________________________________________________

For

the Failure analysis of the machine, modal analysis and harmonic analysis

required to be carried out:

1. Modal

analysis

Modal analysis is used to determine a structure’s vibration characteristics natural

frequencies and mode shapes. Different mode shapes for different frequencies of

structure can be determined in modal analysis. In modal analysis no any Pre-Stress and preloading’s are applied

to the structure. Only different types of supports are considered in the

analysis. The results of modal analysis is natural

frequencies and the corresponding formation that only related to the inherent

characteristics of the system and free from external forces and the method of

fixing. Natural characteristic includes natural frequency, natural vibration

modes and other modal. Parameters. The purpose of natural characteristic

analysis is to avoid resonance and harmful vibration modes and improve the reliability

and service life of screen and screen frame.

2.

Harmonic Analysis

The dynamic response of the vibrating screen at any moment can be obtained by finite element analysis and the stress distribution and weak point of the vibrating screen can be displayed on the operating frequency by harmonic analysis. In this type of analysis all types of force, pressure, moment, displacement, nodal support, fixed support, elastic support, friction less support can be applied for the analysis.

5.1 Dynamic Finite

Element Model-

The geometric model of the screen box must be make some corresponding

simplifies as possible to reflect the true characteristics of its main

structure under the premise of units less to use or the simple unit form for

finite element model.

The following

simplified steps are taken:

(a) Some small

connectors, fixing bracket, other non-bearing components and functional parts

are omitted.

(b) All

chamfers, fillets, rivets and welding spots are ignored which are not the major

factors to reduce the workload of the modeling.

(c) Ignore the

technological holes and bound holes on the screen box as such small diameter

holes has little effect on general strength and stiffness of the structure, but

the mesh units will greatly increase.

(d) The parts of screen box are thin-walled

plate except the motor base.

Fig 5.1 -CAD Model Of

Inline Konckout Machine

5.2 Connections

and preloading –

Import the modal in the ANSYS for the analysis

purpose. Auto connection feature is used to define all the connection of the geometry.

Spring is used as one more connection for dampers; there are two types of spring’s

1.body-body type 2.Body- ground type.

We have used

body-ground type spring here in this type of spring reference is grounded

(fixed) to the ground i.e there is no any directional moment along any side of

body, it will act as base of spring damper. Scoping- the working part of spring

is considered as mobile direction of body, the direction in which spring is

going to experience compression or expansion. By considering all above

explanation constraints of spring will be GROUND to part 325121 00 003 (upper

part of spring damper support)

Stiffness of

spring 120.94 N/mm^2 is used as one of the input characteristic of spring.

Preloading i.e the approximate load which is acting on the spring is also

considered in the analysis because spring may suffer pre deformation due the

load applied by the whole structure. Approximately 3 ton preload is applied on

the spring.in this analysis only one spring is considered as working condition.

5.3

Meshing of model-

Imported model from CATIA is required to mesh for

further analysis. Efforts are made to achieve finer mesh for accuracy of

results. Finer mesh on the parts likes vibrating box, torsion bar support is

achieved because these component suffer frequent failure during working,

components like frame, supports of damper, angle plates for supporting frame etc.

are relatively less finely meshed because the failure is not frequent for these

parts, also considering time consumed for analysis it is not convenient to achieve

the finer mesh for all

the components.

Fig 5.3.1

meshed model of Inline Knockout Machine

For meshing first auto mesh is generated, face

sizing and edge sizing is applied on the edges of circular part and face sizing

is applied on side walls of the box. Mesh is hex dominant in meshing number of

nodes formed are 403425 and number of elements are 57722.

Chapter 6

MODAL ANALYSIS

____________________________________________________

For the model analysis material

used is mild steel. Material properties of mild are as following

Property

Value

Modulus Of Rigidity

76.92 Gpa

Modulus Of Elasticity

210000Mpa

Density

7860kg/m^3

Poissons Ratio

0.3

Table no 6.1 –Material properties

of mild steel

In modal analysis we have

considered here first ten modes of vibration for analysis.i.e the behavior of

the system for first ten mode and its corresponding frequencies.

1. First mode –

Mode

Effect

Name

of part

Deformation

(mm)

1

Minimum

325 121 00 005

Default

2.9041e-010

Maximum

325 121 00 013

Default

223.78

Fig

6.1-Total deformation-1 at frequency 0 HZ

2. Second Mode-

Mode

Effect

Name

of part

Deformation

(mm)

2

Minimum

325 121 00 005

Default

1.5326e-010

Maximum

325 121 00

013-6

130.58

Fig

6.2-Total deformation-2 at frequency 0 HZ

3. Third Mode-

Mode

Effect

Name

of part

Deformation

(mm)

3

Minimum

325

121 00 005_Default

1.4019e-010

Maximum

325

121 00 013_Default

118.14

Fig

6.3-Total deformation-3 at frequency 0 Hz

4. Fourth Mode-

Mode

Effect

Name

of part

Deformation

(mm)

4

Minimum

325

121 00 013_Default

8.3181e-009

Maximum

325

121 00 003

4.4984

Fig

6.4-Total deformation-4 at frequency 0 HZ

5. Fifth Mode-

Mode

Effect

Name

of part

Deformation

(mm)

5

Minimum

325

121 00 005_Default

7.3041e-010

Maximum

325

121 00 013_Default

172.27

Fig

6.5-Total deformation-5 at frequency 0 HZ

6. Sixth Mode-

Mode

Effect

Name

of part

Deformation

(mm)

6

Minimum

325

121 00 005_Default

1.7307e-010

Maximum

325

121 00 013_Default

177.57

Fig 6.6-Total

deformation-6 at frequency 0 HZ

7. Seventh Mode-

Mode

Effect

Name

of part

Deformation

(mm)

7

Minimum

325

121 00 005_Default

3.2495e-010 mm

Maximum

325

121 00 013_Default

168.73 mm

Fig 6.7-Total deformation-7 at frequency 0.00023262

HZ

8. Eighth Mode-

Mode

Effect

Name

of part

Deformation

(mm)

8

Minimum

325

121 00 005_Default

2.1918e-010 mm

Maximum

325

121 00 013_Default

196.7 mm

Fig 6.8-Total deformation-8 at frequency 0.00055697

HZ

9. Ninth Mode-

Mode

Effect

Name of part

Deformation

(mm)

9

Minimum

325

121 00 005_Default

1.7127e-009

Maximum

325

121 00 013_Default

151.72 mm

Fig 6.9-Total deformation-9 at

frequency 0.0005898 Hz.

10. Tenth Mode-

Mode

Effect

Name

of part

Deformation

(mm)

10

Minimum

325

121 00 018_Default

3.879e-011

Maximum

325

121 00 019

49.666 mm

Fig 6.10- Total deformation-10

at frequency 0.00060832 Hz.

The

following bar chart indicates the frequency at each calculated mode.

Fig 6.1 frequency at each calculated

mode.

Mode

Frequency

Hz

CHARACTERSTIC OF VIBRATION MODE

1.

0.

Rigid motion(translational motion,

pitch vibration) along x,y,z axis at

second compartment.

2.

Rigid motion along x,y,z axis, at

fourth compartment.

3.

Rigid motion along x,y,z axis, at third

compartment.

4.

Displacement at damper support.

5.

Rigid

motion along x,y,z axis, at fourth compartment.

6.

Rigid

motion along x,y,z axis, at fourth compartment.

7.

0.00023262

Rigid

motion along x,y,z axis, at third compartment.

8.

0.00055697

Rigid

motion along x,y,z axis, at first compartment.

9.

0.0005898

Rigid

motion along x,y,z axis, at third compartment

10.

0.00060832

Rigid

motion along x,y,z axis, supporting L plates of screen

Table 6.2 -different modes of natural

frequencies

Chapter 7

REFERENCES

____________________________________________________

1.

Mr Boitumelo Ramatsetse

“Failure and Sensitivity Analysis of a Reconfigurable Vibrating Screen Using

Finite Element Analysis”, “Case Studies In Engineering Failure Analysis”.

2. Sergio

Baragetti “Innovative structural solution for heavy loaded vibrating screens”, Minerals

Engineering 84 (2015) 15–26.

3.

Yongjun

Hou, Pan Fang and Lian Zeng,” Finite

Element Analysis of Dual-frequency Vibrating Screen”, Advanced Materials Research

Vols. 479-481 (2012) pp 2124-2128.

4.

Liu

Xinyong,Cui Hongbin,Cao Pengxian,Bao Xuechun,Liu Xinyu, “TQLZ Self-balance Vibrating Screen Static and

Modal Analysis”, Advanced Materials Research

Vol. 852 (2014) pp 619-623.

5. Zhong-jun YIN, Lei

ZHANG, Bing CHEN , “Kinematic and

Dynamic Analysis of Large Coal Vibrating Screen” Applied Mechanics and Materials Vols. 105-107 (2012) pp 444-447.

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Screen” Applied Mechanics and

Materials Vol. 141 (2012) pp 134-138.

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investigation on anti-vibration springs” Engineering Failure Analysis 16 (2009)

1366–1378.