COMPUTER AIDED PROGRAMMING OF A CNC LATHE by ROBERT KEITH MOORE B.Eng ...

109 Pages·2010·5.75 MB·English

COMPUTER AIDED PROGRAMMING
OF A CNC LATHE
by
ROBERT KEITH MOORE
B.Eng., Memorial University of Newfoundland, 1983
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF APPLIED SCIENCE
in
THE FACULTY OF GRADUATE STUDIES
Department of Mechanical Engineering
We accept this thesis as conforming
to the required standard
THE UNIVERSITY OF BRITISH COLUMBIA
September 1985
© Robert Keith Moore, 1985
§0
In presenting this thesis in partial fulfilment of the
requirements for an advanced degree at the University
of British Columbia, I agree that the Library shall make
it freely available for reference and study. I further
agree that permission for extensive copying of this thesis
for scholarly purposes may be granted by the head of my
department or by his or her representatives. It is
understood that copying or publication of this thesis
for financial gain shall not be allowed without my written
permission.
Department of
The University of British Columbia
1956 Main Mall
Vancouver, Canada
V6T 1Y3
Date
Page ii
ABSTRACT
A software package and associated hardware have been
developed which gives users of the ORAC CNC Training Lathe an
easier and faster method of manufacturing on the lathe. The
package, entitled ORACAP, uses the computing power of a
mini-mainframe computer, a VAX 11/750, to assist in part design,
program generation, program optimization, and program proving for
the ORAC Lathe. The package is designed for users unfamiliar
with computers such as students in an educational institute or
workers in a production facility and uses command procedures to
simplify the preparation and execution of the modules of the
package. In addition to providing users with a valuable tool for
manufacturing, ORACAP also gives users insight into the Computer
Aided Design and Computer Aided Manufacturing methods used in
industry, that i s, it demonstrates the methods which allow
production of a part from a very concise description of i ts
geometry. Finally, ORACAP demonstrates the production advantages
of a CAD/CAM system over conventional manufacturing methods for
small to medium size batch production.
Page i ii
CONTENTS
ABSTRACT ii
TABLES vi
FIGURES v ii
ACKNOWLEDGEMENT v i ii
CHAPTER 1 - Introduction
1.1 History of Computer Numerical Control 1
1.2 Advantages of Computer Numerical Control 2
1.3 NC and CNC Programming 3
CHAPTER 2 - ORAC CNC Training Lathe
2.1 Description 6
2.2 Interfacing the Lathe and the Computer 8
2.3 Modifications to the Lathe 10
2.4 Programming the Lathe 17
2.5 Setup of the Lathe 18
CHAPTER 3 - Overview of ORACAP Program
3.1 ORACAP Options 20
3.2 ORACAP Capabilities and Limitations 21
3.3 Instruction and Program Formats 22
3.4 Use of Subdirectories 23
3.5 Terminals 23
CHAPTER 4 - ORACAP Program Execution
4.1 Use of Example Parts 25
4.2 Setup of ORACAP Program Modules 25
4.3 Program Modes and Filenames 26
4.4 Terminal Selection 28
4.5 Option Selection 29
Page iv
4.5.1 DESIGN Option 30
4.5.2 GENERATE Option 38
4.5.3 OPTIMIZE Option 46
4.5.4 ASSEMBLE Option 48
4.5.5 PROVE Option . . . .. 50
4.5.6 PLOT Option 52
4.5.7 VAXTOORAC Option 59
4.5.8 ORACTOVAX Option 59
4.5.9 COMPRESS Option 60
4.5.10 WRITE Option 60
4.6 Description of ORACAP Sub-Programs 61
CHAPTER 5 - Conclusion
5.1 Contributions of ORACAP 65
5.2 Comparison of Various Manufacturing Methods . . 66
5.3 Uses of ORACAP Package 67
REFERENCES 69
BIBLIOGRAPHY 70
APPENDIX A - ORACAP Chess Piece Example Table 72
APPENDIX B - ORACAP Chess Piece Example Files 73
B.1 [ME258.LATHE.DAT]QUEEN.CAD 73
B.2 [ME258.LATHE.DAT]QUEEN.END 74
B.3 [ME258.LATHE .DAT]QUEEN .FIL 74
B.4 [ME258.LATHE.DAT]QUEEN.OUT 74
B.5 [ME258.LATHE.DAT]QUEEN.SIZ 74
B.6 [ ME 2 5 8. LATHE. CNC] QUEEN 1 .ANC 75
B.7 [ ME2 58. LATHE. CNC] QUEEN 1 .BNC 78
B.8 [ME258.LATHE.CNC]QUEEN1.CNC 80
B.9 [ME258.LATHE.PLT]QUEEN 1 .PTX 83
Page v
APPENDIX C - ORACAP Master Part Example Table 86
APPENDIX D - ORACAP Master Part Example Files 87
D.1 [ME258.LATHE.DAT]MASTER.CAD 87
D.2 [ME258.LATHE.DAT]MASTER.END 88
D.3 [ME258.LATHE.DAT]MASTER.FIL 88
D.4 [ME258.LATHE.DAT]MASTER.OUT 88
D.5 [ME258.LATHE.DAT]MASTER.SIZ 88
D.6 [ME258.LATHE.CNC]MASTER1.ANC 89
D.7 [ME258.LATHE.CNC]MASTER1.BNC 92
D.8 [ME258.LATHE.CNC]MASTER1.CNC 94
D. 9 [ME258.LATHE.PLT]MASTER1.PTX 97
APPENDIX E - Data File for ORACAP Materials 100
E. 1 [ME258.LATHE.DATjMATERIAL.DAT 100
APPENDIX F - Microfiche Listing of ORACAP Programs ^y<2.c-( <*X
Page vi
TABLES
I. Production Times for Batch Size of 1 67
II. Production Times for Batch Size of 25 67
III. File Sizes for Chess Piece Example 72
IV. File Sizes for Master Part Example 86
Page v ii
FIGURES
1 . Axes of the ORAC CNC Lathe 7
2. Tool Turret Assembly Drawing 11
3. Tool Turret - Clamp Cylinder 12
4. Tool Turret - Tool Holder and Rotate Cylinder . . 13
5. Tool Turret Parts 14
6. Schematic of Tool Turret Pneumatics 16
7. Dimensioned Drawing of Example Chess Piece . . .. 32
8. Dimensioned Drawing of ORACAP Master Part . . .. 33
9. Plot of Example Chess Piece Sections 35
10. Plot of ORACAP Master Part Sections 36
11. Example of Inaccessible Area 42
12. Rough Cuts Required for Example Chess Piece . .. 44
13. Rough Cuts Required for ORACAP Master Part . . .. 45
14. Proof of Rough Cuts for Example Chess Piece . .. 54
15. Proof of Rough Cuts for ORACAP Master Part . . .. 55
16. Proof of Remaining Cuts for Example Chess Piece . 56
17. Proof of Remaining Cuts for ORACAP Master Part . . 57
18. Proof of ORACAP Master Part with Errors 58
Page v i ii
ACKNOWLEDGEMENT
The author would like to thank his supervisor, Dr. F.
Sassani, for the guidance and assistance provided during the past
two years. Many thanks are extended to Mr. Max Kean who provided
much help and made many suggestions for a ll aspects of this work.
Thanks are also due to the VAX Computer System Manager, Mr. Alan
Steeves, who provided solutions for many hardware and software
problems encountered during this project.
Assistance from the Machine Shop personnel is also
greatly appreciated. Special thanks are due to Mr. Leonard
Drakes for his expert comment on the design of the tool turret
and for the time spent manufacturing i t. Also, thanks to Mr.
Dave Camp for his participation in the production time studies.
Finally, acknowledgement must be made to the Natural
Sciences and Engineering Council of Canada who provided the
scholarship which enabled this work.
Page 1
CHAPTER 1
Introduction
1.1 History of Computer Numerical Control
Since machine tools were first invented, many
modifications have been made to enable faster and easier
production of machine products. One example of this is the
turning lathe. It has evolved from a fully manual operation,
which required a highly skilled operator, into a fully computer
numerically controlled process. As parts became more complex and
tolerances decreased, increased operator skill and time were
required. Therefore, more sophisticated machines were needed to
meet the demand. This resulted in the development of the
automatic lathe which incorporated limit switches to assist part
production, and copying machines which copied a master part by
tracing i ts outline. These devices reduced the time and skill
requirements while maintaining the flexibility required for small
batch jobs. In 1952 the Massachusetts Institute of Technology
contributed to the evolution of machine tools by developing the
first NC (numerically controlled) milling machine [1]. This
again reduced time and skill requirements. Next, the use of
computers to directly control many NC machines (DNC - Direct
Numerical Control) was introduced. This finally led to the
development of micro-processors or computers to control
individual NC machines (CNC - Computer Numerical Control). From
this, it can be seen that the manufacturing industry has become
increasingly reliant on computers and micro-processors for
control of manufacturing equipment.