VIRTUAL INSTRUMENTATION OF PIN ON DISC INSTRUMENT

Bona fide record of work done by

K. VIGNESH (09P653)

S. VIMAL (09P654)

P. VISHNU RAM (09P655)

S. ARUN KUMAR (10P901)

Preliminary mini-project dissertation submitted in partial fulfillment

of the requirements for the degree of

BACHELOR OF ENGINEERING (SANDWICH)

Branch: PRODUCTION ENGINEERING

Of Anna University, Chennai.

MACRH 2012

DEPARTMENT OF PRODUCTION ENGINEERING

PSG COLLEGE OF TECHNOLOGY

(Autonomous Institution affiliated to Anna University, Coimbatore)

COIMBATORE – 641 004.

FACULTY GUIDE

CONTENTS
CONTENT Page No
ACKNOWLEDGEMENT

SYNOPSIS

LIST OF FIGURE

CHAPTER

1. INTRODUCTION...........………………………...……..………………………........1 1. VIRTUAL INSTRUMENTATION 1 2. LabVIEW 2 3. PIN ON DISC INSTRUMENT 3

2. LITERATURE SURVEY……………………..…………………………..………….5

3. PROBLEM DEFINITION AND OBJECTIVE……………………………......…….8 3.1 PROBLEM DEFINITION 8 3.2 OBJECTIVE 8

4. METHODOLOGY………………………………………………………….………....9

5. PROCEDURE AND RESULTS…………………………………...…..……10 5.1 Calibrating the Pin on Disc Instrument 10 5.2 Conversion of Time to Sliding Distance 11 5.3 Exporting Values to Spreadsheet File 12 5.4 Steps to Run the Program 13

6. CONCLUSION………………..………………………………..….…….....…...…...15

BIBLIOGRAPHY..........................................................................................................16
ACKNOWLEDGEMENT

We would like to express our sincere gratitude and profound thanks to

Dr. R. Rudramoorthy, Principal, PSG College of Technology, for his inevitable encouragement and support.

We extend our profound gratitude to Dr. K. Prakasan, Professor and Head, Department of Production Engineering, PSG College of Technology, who has always been a source of inspiration.

We would like to thank our faculty guide, Mr. K. Somasundara Vinoth, Assistant Professor, Department of Production Engineering, PSG College of Technology, for his constant enthusiasm, support and valuable guidance throughout the project.

We are indebted to our Project Committee staff members Dr. S. Saravanan, Associate professor, Dr. G. Madhan Mohan, Assistant professor (senior grade), Mr. V. Jaiganesh, Assistant professor (senior Grade), Mr. J. Pradeep Kumar, Assistant Professor, Department of Production engineering, PSG College Of Technology for their guidance.

We would like to acknowledge the support and enthusiasm provided by our tutor Mr. K. Somasundara Vinoth, Assistant Professor, Department of Production Engineering, PSG College of Technology.

We would like to thank our Production Engineering lab for their support.

Finally we would like to thank our fellow class mates for their encouragement throughout the project.

SYNOPSIS

A pin on disc tribometer is a standard equipment used to evaluate the wear and friction characteristics of a given test specimen. The current set-up of the instrument in the production engineering department lab enables the operator to note down the reading from the display at regular intervals of time and then plot the characteristics for the specimen.

The primary objective of the project work is to interface the pin on disc instrument with a PC and acquire the values automatically using LabVIEW and plot the friction and wear characteristics. The values thus obtained from the pin on disc apparatus must be stored in a spreadsheet for future references. The VI is developed in such a way that the values are directly store in the spreadsheet file which can be saved and used for future references. [pic]

CHAPTER 1

INTRODUCTION

1.1 VIRTUAL INSTRUMENTATION

Virtual Instrumentation is the use of customizable software and modular measurement hardware to create user-defined measurement systems, called virtual instruments.

'Traditional' or 'natural' instrumentation systems are made up of pre-defined hardware components, such as digital multimeters and oscilloscopes that are completely specific to their stimulus, analysis, or measurement function. Because of their hard-coded function, these systems are more limited in their versatility than virtual instrumentation systems. The primary difference between 'natural' instrumentation and virtual instrumentation is the software component of a virtual instrument. The software enables complex and expensive equipment to be replaced by simpler and less expensive hardware; e.g. analog to digital converter can act as a hardware complement of a virtual oscilloscope, a potentiostat enables frequency response acquisition and analysis in electrochemical impedance spectroscopy with virtual instrumentation.

The concept of a synthetic instrument is a subset of the virtual instrument concept. A synthetic instrument is a kind of virtual instrument that is purely software defined. A synthetic instrument performs a specific synthesis, analysis, or measurement function on completely generic, measurement agnostic hardware. Virtual instruments can still have measurement specific hardware, and tend to emphasize modular hardware approaches that facilitate this specificity. Hardware supporting synthetic instruments is by definition not specific to the measurement, nor is it necessarily (or usually) modular.

Leveraging commercially available technologies, such as the PC and the analog to digital converter, virtual instrumentation has grown significantly since its inception in the late 1970s. Additionally, software packages like National Instruments Lab VIEW and other graphical programming languages helped grow adoption by making it easier for non-programmers to develop systems.

1.2 Lab VIEW

Lab VIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a platform and development environment for a visual programming language from National Instruments. Originally released for the Apple Macintosh in 1986, Lab VIEW is commonly used for data acquisition, instrument control, and industrial automation on a variety of platforms including Microsoft Windows, various flavors of UNIX, Linux, and Mac OS. The programming language used in Lab VIEW, is a dataflow language. Execution is determined by the structure of a graphical block diagram.

Lab VIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a platform and development environment for a visual programming language from National Instruments. Since this might be the case for multiple nodes simultaneously, it is inherently capable of parallel execution. Furthermore, Lab VIEW does not require type definition of the variables; the wire type is defined by the data-supplying node.

Lab VIEW is a platform and development environment for a visual programming language from National Instruments. The graphical language is named "G". Originally released for the Apple Macintosh in 1986, LabVIEW is commonly used for data acquisition, instrument control, and industrial automation on a variety of platforms including Microsoft Windows, various flavors of UNIX, Linux, and Mac OS. The latest version of LabVIEW is version 8.20, released in honor of LabVIEW's 20th anniversary.

1.3 PIN ON DISC INSTRUMENT

A pin on disc tribometer is the standard equipment used to determine the sliding friction coefficient and wear resistance of surfaces. The tester consists of a stationary “pin” under an applied load in contact with a rotating disc. Either the pin or the disc can be wear and friction tested using the pin on disc tester. The pin is usually a sphere however it may be any geometry that simulates the actual application counter surface.

The pin on disc machine is a versatile unit designed to evaluate the wear and friction characteristics. The sliding friction test occurs between a stationary pin stylus and a rotating disc. Normal load, rotational speed and wear track diameter can be varied. Electronic sensors monitor wear and the tangential force of friction as a function of load, speed, lubrication or environmental condition.

The specifications of the pin on disc machine used are mentioned below.

Conforms to the specifications of : ASTM G99
Sliding Speed Range : 0.26-10 m/sec
Disc Rotation Speed : 100-2000 rpm
Maximum Normal Load : 200 N
Frictional Force : 0-200 N
Wear Measurement Range : 4 mm
Pin Size : 3-12 mm diagonal/diameter
Disc Size : 160 mm x 8 mm thick
Wear Track Diameter : 10-140 mm
[pic]
Fig 1.1 Pin on Disc Instrument
CHAPTER 2

LITERATURE REVIEW

The literature survey was carried out to learn about the different approaches to create a virtual instrument using LabVIEW software.

A virtual instrument that automates the obtaining of real vibration patterns of a piezoelectric device. Input data are received from transducers and sent to a DAQ card. Data received from transducers are processed by the DAQ card and the output data from the card is manipulated using the software LabVIEW. F.J.Jimenez et al [1] developed a virtual instrument that allows the visualization of vibration patterns for piezoelectric samples.

A complex virtual instrumentation based system for measurements of mechanical and thermal parameters of an ancient masonary bell tower is described by Moschioni Giovanni [2] in this paper. The data from different LVDT s , RTD s, accelerometers and anemometers are collected and sent to a PC for data manipulation. Using the software LabVIEW the data is processed and the different parameters such as wind velocity, vibrations measured on the walls of the tower during gust can be found. A virtual instrumentation based data acquisition system, set up for a long term campaign on an ancient masonary tower is presented. The acquisition system provides on-line analysis of dynamic data in order to track the mean behavior which makes it possible to evaluate the present state of the tower.

Control of fins for motion stabilization of a ship is achieved entirely using a virtual instrumentation based system. The roll angle of the ship is acquired through a Clinometer and the data is sent for processing. V. Anantha Subramanian et al [3] has developed a virtual instrument and the data is manipulated using LabVIEW software and the fin is controlled according to the roll angle experienced by the ship. The motion signal obtained from the clinometers is converted to digital signal and all further manipulation and generation of feedback control are done in the LabVIEW environment. The flexibility and versatility of the tool is demonstrated in the successful results of stabilization tests carried out on the yacht.

Jian Yin et al [4] has developed a new motorized spindle performance monitoring system based on the LabVIEW software platform. Experimental results show that the system developed by him is efficient for acquiring, analyzing, presenting sensory signals simultaneously, while the developed signal processing techniques are effective for detecting the performance of motorized spindle. The whole system is composed of the following parts: sensing, data acquisition and displaying, condition monitoring and signal analysis. Experimental results show that the developed monitoring system is efficient for acquiring, analyzing, presenting sensory signals simultaneously, while the developed signal processing techniques are effective for detecting the performance of motorized spindle.

Subhransu Padhee et al [5] has done a case study of a plant consisting of multiple boilers where multiple process variables of the boilers need to be acquired from the field and monitored. This paper gives an overview of data acquisition, data logging and supervisory control system of a plant consisting of multiple boilers. Data acquisition, data logging and supervisory control are the basic building blocks of plant automation. The data of the process variables needs to be logged in a database for further analysis and supervisory control. He has developed a Labview based data logging and supervisory control program that simulates the process and the generated data are logged into the database with proper indication about the status of the process variable.

Sandu Florin et al [6] presents the development of a data acquisition system dedicated to the study of Peltier and Seebeck effect and to the performance parameters of a commercial thermoelectric semiconductor element. It was used a National Instruments NI USB-6008 Data Acquisition System (connected to National Semiconductor LM35 temperature sensors) to build a Virtual Instrumentation system programmed in NI LabView. There are presented computational models and experimental data interpretations.

This paper presents a virtual-instrumentation system (VIS) that aims at measuring the evolution of key magnitudes in a non conventional machining process called wire electrical discharge machining (WEDM). The VIS consists of two well different parts: the acquisition system that measures process signals (voltage and current) and the virtual measurement of relevant magnitudes (such as energy, peak-current distribution, and ignition delay time). E. Portillo et al [7] has developed the data-acquisition system that provides flexibility and ease of storing tests under different machining conditions without extra hardware construction or adaptation. It is based on a commercial data-acquisition board that works at very high frequencies (up to 10 MSamples/s). The virtual measurement is carried out by modeling and processing the acquired signals. The VIS has been employed to monitor and detect low-quality cutting in WEDM.

This paper presents the design, optimization, and implementation of a virtual instrument (VI), which is an essential part of an integrated bearing condition monitoring system. Changting Wang [8] has designed a VI using the graphical programming language LabVIEW and is capable of performing on-line measurement functions, including data acquisition, display, and analyses in the time and frequency domains, as well as data archiving. The issues of data length selection and VI real-time capability have been investigated to optimize the VI operation and improve data-processing efficiency. The VI system presents an effective and user-friendly human–machine interface for on-line bearing condition monitoring, which is of critical importance to real-time fault diagnosis and intelligent manufacturing.

CHAPTER 3

PROBLEM DEFINITION AND OBJECTIVE

3.1 PROBLEM DEFINITION:

The amount of error, while drawing wear and frictional characteristics graph, is very high. This is because the current set up of the instrument facilitates only manual tabulation of readings of wear and frictional force, i.e. the operator has to keep track of time manually, as well as note down the readings at regular intervals of time. Since both the process of keeping track of time and noting down the readings is done by the operator, it results in errors.

Another limitation is that, since the readings are noted down manually by an operator, only fewer values are noted down with respect to time. This results in graphs which are less accurate and depend more on approximation of the shape of the graph. The values thus noted down also have to be kept in hard copy which makes it difficult to document and maintain it for future reference.

3.2 OBJECTIVE:

The objective of this project is to completely eliminate the human errors in obtaining the various graphs. The apparatus is interfaced with a PC and this will enable the operator to obtain the graph directly from the computer. The graph thus obtained from the PC will be more accurate. This is because, by interfacing the apparatus with a PC, we enable it to obtain 2 values for every 0.5 seconds (frequency of obtaining the values and the number of values can be changed).

Moreover, the values obtained from the apparatus can be exported to a spreadsheet file directly and it can be saved. So this will enable the operator to store large volume of data in the form of spreadsheets which can be documented easily and can also be stored for future references.
CHAPTER 4

METHODOLOGY

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Fig 4.1 Methodology

CHAPTER 5

PROCEDURE AND RESULTS

5.1 Calibrating the Pin on Disc instrument:

The LVDT and the load cell of the pin on disc instrument has to be calibrated in order to acquire the data in PC. The steps to be followed in calibrating the load cell and LVDT are as follows.

• The NI DAQ card is connected with the wear testing instrument and computer.

• The voltage developed by load cell and LVDT are taken and given to a0 and a1 as analog signals to the DAQ card.

• The LabVIEW 9.2 is opened in the computer.

• Select Blank VI from the dialog box. It contains the front panel and block diagram.

• Right click in the block diagram and then select the DAQ card. Then select acquire signals.

• In that, signals from a0 and a1 are selected (according to the pin inputs of the wires from the sensors connected to the DAQ card).

• The RSE is selected and then the number of samples that has to be acquired in a second should be specified.

• Now the DAQ card is initialized in the front panel.

• Right click in the block diagram, select create and then numeric indicator.

• The numeric indicator shows the voltage developed by the load cell and LVDT.

• The specimen to be tested is clamped which acts as a pin with the specified track diameter.

• The pin on disc instrument is switched on. The disc rotates for a given period of time.

• The wear and frictional force for the specimen is noted continuously. Simultaneously the voltage developed by the load cell and LVDT is also noted from numeric indicator display.

• We noticed that the LVDT voltage is directly proportional to the wear and load voltage is directly proportional to the frictional force.

• The voltage developed by LVDT and the corresponding wear reading is tabulated in the spreadsheet.

• The graph is plotted between them and the equation for the curve is found.

• Similarly another graph is plotted between load cell voltage and its corresponding frictional force value. The equation for this curve is also found with the help of spreadsheet.

• Right click in the block diagram, select arithmetic and then select formulae. In that insert the LVDT voltage versus wear equation.

• The LVDT voltage is fed as input to the formulae.

• The output value from formulae is taken and given to the new numeric indicator. This value is the wear value.

• Similarly another formulae icon is created in which the equation of friction force versus load cell voltage is inserted.

• Load cell voltage is given as input to this formulae icon.

• The output value from formulae is taken and given to the new numeric indicator. This value is the frictional force value.

5.2 Conversion of time to Sliding Distance:

In wear testing the comparison between the wear with respect to distance travelled by pin is necessary.

• To calculate distance another formulae icon is used. The input parameters for calculating the sliding distance are track diameter, RPM and time.

• The preset track diameter and RPM values are given manually with the help of the two numeric controllers created. In one numeric control the track diameter is entered and in the other numeric controller, the RPM is entered.

• For time input “elapsed time” icon is selected. And the output of this icon is fed to formulae. This icon automatically generates time when program starts running.

• The distance travelled formulae is inserted in the formulae icon.

• The output is indicated through the numeric indicator.

• To find the distance travelled by the pin the following formulae is used

Distance travelled =[pic]

Where, D- Track diameter

N- RPM of the disc

t- time in seconds

Now the wear, frictional force and distance can be directly observed in the front panel itself without the help of instrument.

5.3 Exporting values to spreadsheet file:

These values should be stored periodically in excel for the further reference. The steps to be followed to store the values in a spreadsheet are as follows,

• To achieve this, right click in the block diagram and select “Write To Measurement File”

[pic]

Fig 5.1 Write To Measurement File Dialog Box

• The above displayed dialog box will be opened.

• Select to store the data in .lvm format and specify the file path with the name of the file.

• For better understanding graphical representation between distance travelled versus wear and distance travelled versus frictional force is needed.

• To achieve this right click on the front panel and then select insert charts.

• The X-axis value is given as distance travelled and Y-axis value is given as wear from their numeric indicators respectively.

• Similarly another graph is inserted between distance travelled versus frictional force.

• Now the LabVIEW program is ready to run.

5.4 Steps to run the program:

The program is run by following the steps given below,

• The specimen to be tested is placed as a pin with required track diameter and RPM. These values are also fed into the numeric controller for calculation of distance travelled.

• Select the run continuously option in the front panel when pin on disc apparatus is started.

• The graphs are observed in the front panel with their values during the running the program.

• After the observations click stop in the block diagram.

• The values are automatically stored in excel because of the program.

• The graphs are also can be plotted in excel. The graphs can be saved for further reference. The front panel and block diagrams are shown in figure.

[pic]

Fig 5.2 Spreadsheet File With Graphs

[pic]

Fig 5.3 Block Diagram

CONCLUSION

Conclusion: The pin on disc instrument has been successfully interfaced with a PC with the aid of a NI-DAQ USB 6009 and using the software LabVIEW. Now all the data which is acquired from the load cell and LVDT of the pin on disc instrument is sent to the PC via the NI-DAQ card. All the data thus received are manipulated using LabVIEW and the wear characteristics and the frictional characteristics are obtained in the front panel of the VI file.The values thus obtained from the LVDT and the load cell are stored in MS-Excel spreadsheet which can be saved for future references.

Future Work: With the available components we have successfully interfaced the pin on disc instrument with a PC and have obtained the wear and frictional characteristics of a specimen being tested. The phase two of the project can be continued by purchasing the required equipments and create a virtual instrument such that it enables the operator to control the pin on disc instrument completely through the PC i.e. the instrument can be started and stopped with the help of the buttons in the front panel of the VI file in LabVIEW.

BIBLIOGRAPHY

1. F.J. Jimenez, J. De Frutos, “Virtual instrument for measurement, processing data, and visualization of vibration patterns of piezoelectric devices” Computer Standards & Interfaces 27 (2005) 653-663.

2. Giovanni Moschioni, “A Virtual Instrumentation System for Measurements on the Tallest Medieval Bell Tower in Europe” IEEE Transactions on Instrumentation and Measurement, Vol. 52, NO. 3, June 2003.

3. V. Anantha Subramanian, G. Ashokumar, V, Jagadeesh Kumar, “Active Fin Control for Yacht Using Virtual Instrumentation”, Ocean Engineering, Volume 34, Issues 3-4, March 2007, Pages 390-402.

4. Yin Jian, Liangyin Jiang, Ming Li, “Virtual Instrumentation For Motorized Spindle Performance Monitoring” 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering (CMCE).

5. Subhransu Padhee, Yaduvir Singh, “Data Logging and Supervisory Control of Process Using LabVIEW”, Proceedings of the 2011 IEEE Students’ Technology Symposium, 14-16 January, 2011, IIT Kharagpur.

6. Florin SANDU, Venetia SANDU, Stefan NAN, Adrian Iulian DUMITRU, “Data Acquisition and Virtual Instrumentation System for the Study of Peltier and Seeback Effects”, 2010, 12th International Conference on Optimization of Electrical and Electronic Equipment, OPTIM 2010.

7. E. Portillo, I. Cabanes, M. Marcos, D. Orive, J. A. Sanchez, “Design of a Virtual-Instrumentation System for a Machining Process”, IEEE Transactions on Instrumentation and Measurement, Vol. 56, No. 6, December 2007.

8. Changting Wang, Robert X Gao, “A Virtual Instrumentation System for Integrated Bearing Condition Monitoring”, IEEE Transactions on Instrumentation and Measurement, Vol. 49, No. 2, April 2000.

-----------------------
CONCLUSION

STORE VALUES IN EXCEL

GRAPHICAL REPRESENTATIONS

CONSTRUCTION OF BLOCK DIAGRAM

SELECTING LABVIEW

FINDING DIFFERENT METHODS

OBJECTIVES

LITRATURE SURVEY

PROBLEM IDENTIFICATION