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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 6, Issue 11, Nov 2015, pp. 158-175, Article ID: IJMET_06_11_019
Available online at
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=6&IType=11
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
DESIGN AND OPTIMIZATION OF
CRITICAL PART OF A ROTARY TABLE
USED IN HORIZONTAL MACHINING
CENTRE
Mr. Kadam Pradip Vasantrao
PG Student, M.E.Design,
P.V/P.I.T. Budhgaon 416304, Sangli-Tasgaon Road, Maharashtra India
Prof. N. V. Hargude,
Associate Prof. Dean R and D, P.V/P.I.T. Budhgaon 416304, Sangli-Tasgaon Road, Maharashtra India
ABSTRACT
Growing industry demands low manufacturing cost, saving of material,
low cost material, ease of transportation etc. This demand leads to use
different type of material and various techniques to increase productivity. The
time factor is very important during loading and unloading of job/pallet. In
this research critical parts like Pallet considering machining force taking
weight of the work piece into the account. Analysis of pallet is carried out by
using finite element package.
Key words: Rotary Table, Pallet, Horizontal Machining Centre.
Cite this Article: Mr. Kadam Pradip Vasantrao and Prof. N. V. Hargude.
Design and Optimization of Critical Part of A Rotary Table Used in
Horizontal Machining Centre. International Journal of Mechanical
Engineering and Technology, 6(11), 2015, pp. 158-175.
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=6&IType=11
1. INTRODUCTION
CNC rotary table is a work holding device used on machining centers to position the
component in desired angle to do multi-face operation in one setup. The table can also
be interpolated as a 4th axis with machines X, Y, Z axes to enable machining of
profiles such as cam, which is out of reach with only 3 axes of the machining centers.
Rotary axis is essential for machining the complex jobs where the machining forces
are not at 90 or 180 degree to each other. Even if the jobs are rectangular, these can be
machined in one setup using rotary table to improve the accuracy and productivity.
Rotary table is designed with heavy duty axial radial roller bearing to take heavy
Mr. Kadam Pradip Vasantrao and Prof. N. V. Hargude
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loads. Rotary tables with dual lead worm and worm wheel with from correction are
widely used for longer life and sustained accuracy as shown in Fig.1.1
Figure 1.1 Rotary Table with worm screw and worm wheel device
2. LITERATURE REVIEW
Fred M plus et al [1], this paper which describes the pallet loading conditions and
pallet operation for the IBM R 8/1 are developed and also a systematic algorithm is
invented.
Michael wang, suresh sethi et al [2], this paper represents the computational
complexity of the problem of minimizing make span in a flow shop , where each jobs
requires a pallet the entire time, from the start of its first operation until the
completion of the last operation. Hence it is prove that the problem is NP-hard in the
strong sense for m > 2 and k > 3, and for, m> 3 and k> 2, where m is the number of
machines and k is the number of pallets in the system.
Terry D. Gerhardt et al [3] ,This paper focuses on the effect of notches on the on
pallet stringers such as stiffness and strength of pallet by changing the notch depth
and radius of the stringers of pallet and also developed the design equations for
conventional double notched oak pallet stringers by using the experimental method
and finite element approach.
H. Weule1, J. Fleischer1 W et al [4] , In this paper which explained the topology
method for optimizing the machine tools by using numerical methods such as finite
element method (FEM) and multi-body simulation (MBS) and coupled each other, for
this critical workspace positions, loading conditions are considered.
Carsten Daub et al [5] ,in this a cast model is developed to enhance the
effectiveness of machining centers with multi pallet changers, further a heuristic
scheduling algorithm is developed to minimize the total weighted tardiness.
Juan Pablo Leiva, Brian C at al [6] ,this paper which explains the difference
between the topology and topometry methods when employed to the structural
components such as what element types are available for each method and what types
of analysis and responses can be used for each method are presented in the genesis
program also explained the concepts that help solve larger problems in a reduced
number of cycles.
LubomírNovotný, JiříMarek et al [7] ,In this paper a detail study on pallet of
size 800 mm is studied which covers the modeling of the. Component then the
loading carrying capacity (deformation) is checked by using numerical methods
considering load, machining operations and high speed of 600 min–1.
Design and Optimization of Critical Part of A Rotary Table Used in Horizontal Machining
Centre
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ParagVichare, AydinNassehi et al [8] , In this a detail study is done on the
fixture used in the universal vises, chucks, pallets, auxiliary rotary tables when used in
CNC machining center for Unified Manufacturing Resource Model.
S. Pellegrinellia, A. Valentea et al [9] , this research work proposes an integrated
methodology and a software infrastructure to support the process planning and pallet
configuration solutions whose major goal is to minimizing production costs –
including costs for energy consumption and cutting tool wear - while maximizing the
number of finished work pieces per pallet.
Abdullah Waseem, Ahmad Nawaz et al [10] ,In this a PVC made pallet are
developed and analyzed for the uniformly distributed static load on pallet by using the
Pro-E and ANSYS packages further deformation and stress developed in the pallet are
compared with the other material pallet.
Mohit Law, Yusuf Altintas[11] ,In this optimization of machine tools is carried
out by using the position-dependent stability. For this identified weak machine
component is modified based on reduced model sub structural synthesis and the
complete dynamics are rapidly analyzed by virtually re-assembling the machine using
reduced order models.
S. Pellegrinellia,n, T.Tolio a, [12] ,This paper studied the pallet sequencing
based on the network part program logic. Part program of non-production movements
for each possible sequence of two operations are automatically generated at the shop
floor level are simulated to obtain the non-production time.
3. STATIC STRUCTURAL ANALYSIS
A static structural analysis determines the displacements, stresses, strains, and forces
in structures or components caused by loads that do not induce significant inertia and
damping effects. Steady loading and response conditions are assumed; that is, the
loads and the structure's response are assumed to vary slowly with respect to time.
4. STATIC STRUCTURAL ANALYSIS OF EXISTING PALLET:
Figure 4.1 Drawing of Existing Pallet
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Figure 4.2 Existing Pallet With Applied Pressure
Figure 4.3 Meshed Model of Existing Pallet
Figure 4.4 Total Deformation of Existing Pallet
Figure 4.5 Von Mises Stress in Existing pallet
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5. STATIC STRUCTURAL ANALYSIS OF FINAL MODIFIED
PALLET
Figure 5.1 Drawing of Final Modified Pallet
Figure 5.2 Final Modified Pallet
Figure 5.3 Meshed Model of Final Modified Pallet
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Figure 5.4 Total Deformation of Final Modified Pallet
Figure 5.5 Von Mises Stress In Final Modified Pallet
Particular Existing
Model
Final
Modified
1. Stress (MPa) 49 31
2. Deflection (micron) 4 3
5.1. Discussion on Results Obtained:
From above table we found that the final modified pallet has less deflection as 3.334
micron and Von mises stress as 30.856Mpa as compared to existing pallet. Therefore,
modified pallet is safe under static conditions.
6. EXPERIMENTATION ON UTM
6.1. Procedure
1. Fix the pallet in the jaws of UTM
2. Then move the upper jaw in downward direction to fix the pallet and set zero reading
on display.
3. Then adjust the dial gauge of least count 1 micron as shown in photo when reading on
display for offline load is exactly zero.
4. Then gradually apply the load with fixed feeding rate.
5. Stop the machine when it crosses 16 kN.
6. Then note down the reading on display and dial gauge indicator.
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Plate 6.1 Plate
Plate 6.2 Reading of Plate on Display
Plate 6.3 Reading of Dial Gauge Indicator For Plate
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Plate 6.4 Existing Pallet
Plate 6.5 Reading of Existing Pallet on Display
Plate 6.6 Reading of Dial Gauge Indicator For Existing Pallet
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Plate 6.7 Final Modified Pallet
Plate 6.8 Reading of Final Modified Pallet on Display
Plate 6.9 Reading of Dial Gauge Indicator For Final Modified Pallet
Particular Plate Existing Pallet Modified Pallet
Load Applied (kN) 22.10 17.55 18.65
Offline Test Reading (mm) 0.00 0.00 0.00
Dial Guage Reading (micron) 0 6 4.5
From above table we found that the deformation of existing pallet is 6 micron and
deformation of final modified pallet is 4.5 micron. So the deformation of final
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modified pallet is less than the existing pallet. So our design for final modified pallet
is safe. Owing to this, the plate used for application of load over the entire surface of
pallet has no any deformation up to load 22.10 kN. So the plate has no any combine
effect on results obtained for existing pallet and final modified pallet. The UTM has
least count of 10 micron that’s why the deformation on display of UTM shows zero
reading and dial guage indicator used has least count 1 micron so we get the reading
on dial guage indicator as shown in above plates.
Particular Existing
Pallet
Modified
Pallet
Percentage
Weight
Difference
In Existing
And
Modified
Pallet
Theoretical
wt. (kg) 6 4.6 23.33
Actual wt.
(kg) 5.8 4.54 21.72
From above table, we note that there is reduction in weight by 23.33% of final
modified pallet as compared to existing pallet in FEA. In actual case, reduction in
weight of final modified pallet is 21.72 % as compared to actual wt of existing pallet.
Here we note that there are differences in actual and theoretical weights for both
Existing Pallet and final Modified Pallet. This is due to rated material properties used
during casting. So that much difference is negligible.
Particular Existing
Pallet
Modified
Pallet
Deformation In
FEA (micron) 4 3
Deformation On
UTM (micron) 6 4.5
From above table, we note that there is a very slight difference in readings of FEA
and UTM test. This difference is negligible.
7. MODAL ANALYSIS OF FINAL MODIFIED PALLET:
Figure 7.1 Mode 1 of Final Modified Pallet
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Figure 7.2 Mode 2 of Final Modified Pallet
Figure 7.3 Mode 3 of Final Modified Pallet
Modal Analysis Existing Model
Frequencies in Hz
Final Modified
Frequencies in Hz
Mode 1 4691 5581
Mode 2 4913 6191
Mode 3 4914 6240
Modal Frequency Comparison in Hz for fixed boundary conditions
From the above table, it can be concluded that the model frequencies of the
modified pallet is greater than the operating frequencies. Hence there is no any
resonance. So, design of pallet is safe.
The frequency occurred in the final model is greater than the existing designed pallet.
7.1. Modal Analysis For Free Condition
Graph 7.1 Natural Frequencies In Hz of Existing Pallet For Free Condition
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Figure 7.4 Mode 1 of Existing Pallet For Free Condition
Figure 7.5 Mode 2 of Existing Pallet For Free Condition
Figure 7.6 Mode 3 of Existing Pallet For Free Condition
Modal Analysis
From FEA
Existing Pallet
Frequencies in Hz
From FEA
Final Modified Pallet
Frequencies in Hz
From FEA
Mode 1 2122.2 1513
Mode 2 2404.7 2175
Mode 3 2485 3087.6
Modal Frequency Comparison in Hz for free boundary conditions.
From above table we conclude that natural frequency from mode3 is increasing
means modal frequencies of the modified pallet is greater than the operating
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frequencies. The frequencies occurred in the final model is greater than the existing
pallet. Hence there is no any resonance. So, design of final modified pallet is safe.
8. EXPERIMENTATION USING FFT ANALYZER:
Plate 8.1 Hanging of Modified Pallet
Plate 8.2 Hanging of Existing Pallet
Figure 8.1 Natural Frequency in Hz of existing pallet at Mode 1
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Figure 8.2 Natural Frequency in Hz of existing pallet at Mode 2
Figure 8.3 Natural Frequency in Hz of existing pallet at Mode 3
Modal
Analysis
From
FEA
Existing Pallet
Frequencies in Hz
Percentage
difference in
FEA and
FFT Results
of existing
pallet
From
FEA
From
FET
Mode 1 2122.2 1807 14.85
Mode 2 2404.7 2120 11.83
Mode 3 2485 2740 10.26
Comparison Table Of Natural Frequency In Hz From FEA And FFT Of Existing
Pallet
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8.1. Discussion from above Observation Table
From above observation table, we note there is very small percentage difference in
FEA and FFT results. This is less than 20%. This is acceptable. This variation may
occur due to rated material properties, change in mass, change in geometry and
increase or decrease in stiffness values of material.
8.2. Final Model
Figure 8.4 Natural Frequency in Hz of final modified pallet at Mode 1
Figure 8.5 Natural Frequency in Hz of final modified pallet at Mode 2
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Figure 8.6 Natural Frequency in Hz of final modified pallet at Mode 3
Modal
Analysis
From
FEA
Final Modified
Pallet Frequencies
in Hz
Percentage
difference in
FEA and FFT
Results of
final modified
pallet
From
FEA
From
FET
Mode 1 1513 1471 2.77
Mode 2 2175 2449 12.59
Mode 3 2848 3087.6 8.41
Comparison Table of Natural Frequency In Hz From FEA And FFT of Modified
Pallet
8.3. Discussion From Observation Table:
From above observation table, we note there is very small percentage difference in
FEA and FFT results. This is less than 20%. This is acceptable. This variation may
occur due to rated material properties, change in mass, change in geometry and
increase or decrease in stiffness values of material [14, 15].
Comparison Table of Natural Frequency In Hz From FFT of Existing Pallet And
Modified Pallet
Modal
Analysis
From
FFT
Existing Pallet
Frequencies In
Hz From FFT
Final Modified
Pallet
Frequencies In
Hz From FFT
Mode 1 1807 1471
Mode 2 2120 2449
Mode 3 2740 3087.6
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8.4. Discussion On Result Obtained:
From the above tables, it can be concluded that the modal frequencies of the final
modified pallet is greater than the operating frequencies and also frequencies occurred
in the final model is greater than the existing designed pallet. Hence there is no any
resonance. So, design of pallet is safe.
9. CONCLUSIONS:
1. The weight of pallet is reduced, In final designed pallet compare to existing pallet by
21.72 %.
2. From table 4.2, we found that the final modified pallet has less deflection as 3.334
micron and Von mises stress as 30.8Mpa compared to existing pallet. Therefore,
modified pallet is safe under static conditions.
3. From the above tables of natural frequencies, it can be concluded that the model
frequencies of the modified pallet is greater than the operating frequencies. Hence
there is no any resonance. So, design of final modified pallet is safe. The frequency
occurred in the final model is greater than the existing pallet.
4. Due to reduction in weight this final modified pallet can be used as automatic pallet
changer.
5. Reduction in weight of pallets results in to reduced material cost.
6. The provision of T slots in the final modified pallet leads to reduction in
manufacturing complexity.
REFERENCES
[1] Fred M. Pulst and J.M.A.Tanchoco, “ Robotic Implementation of pallet loading
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“Minimizing MakespanInFlowshops with Pallet Requirements: Computational
Complexity” Infor vol. 35, no. 4, Nov. 1997
[3] Terry D. Gerhardt, “Strength and Stiffness Analysis of Notched, Green Oak
Pallet Stringers” United States Department of Agriculture Forest Service, Forest
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