2.2 N/mm^2 CHAPTER 4 Modeling Of The Component _____________________________________________________

2.2 Objectives of
present work

1.     
TO generate Numerical
finite element models to investigate the structural and dynamic behavior of a
vibrating screen.

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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
Default32
 

 
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-7
 

 
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-30

 
 
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-6

 
 
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-6

 
 
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-35
 

 
 
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-8
 

 
 
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-30
 

 
 
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-1
 

 
 
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.

6.      DING Chuanguang, SONG Fangzhen, SONG Boand Men Xiuhua,” The Finite Element Analysis of Vibrating
Screen” Applied Mechanics and
Materials Vol. 141 (2012) pp 134-138.

7.      R.K. Luo, W.J. Mortel, X.P. Wu, “Fatigue failure
investigation on anti-vibration springs” Engineering Failure Analysis 16 (2009)
1366–1378.