design and optimization of critical part of a rotary table used in horizontal machining centre

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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


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


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



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


Centre


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



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.


Centre


Plate 6.1 Plate

Plate 6.2 Reading of Plate on Display

Plate 6.3 Reading of Dial Gauge Indicator For Plate



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


Centre


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



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


Centre




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



Figure 7.4 Mode 1 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


Centre


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





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


Centre


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





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


Centre


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.

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https://www.google.co.in/search?q=Rotary+Table+with+worm+screw+and+worm+wheel+device&biw=1242&bih=615&tbm=isch&tbo=u&source=univ&sa=X&ved=0CC8Q7AlqFQoTCJOiw6LD7McCFQ0ajgodmsUPYg

