Modeling of the Reciprocating, Pneumatic Impact Hammer
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UNLV Retrospective Theses & Dissertations 1-1-2003 Modeling of the reciprocating, pneumatic impact hammer William Allan Bloxsom University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Bloxsom, William Allan, "Modeling of the reciprocating, pneumatic impact hammer" (2003). UNLV Retrospective Theses & Dissertations. 2534. http://dx.doi.org/10.25669/julx-8bgk This Dissertation is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Dissertation has been accepted for inclusion in UNLV Retrospective Theses & Dissertations by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. MODELING OF THE RECIPROCATING, PNEUMATIC IMPACT HAMMER by William A. Bloxsom Bachelor of Science in Industrial Education Eastern Michigan University 1972 Bachelor of Science in Mechanical Engineering University of Colorado 1985 Master of Science In Mechanical Engineering University of Colorado 1991 A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy In Mechanical Engineering Department of Mechanical Engineering Howard R. Hughes College of Engineering Graduate College University of Nevada, Las Vegas August 2003 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3101563 Copyright 2003 by Bloxsom, William Allan All rights reserved. UMI UMI Microform 3101563 Copyright 2003 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Copyright by William A. Bloxsom 2003 AH Rights Reserved Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Dissertation Approval UNIV The Graduate College University of Nevada, Las Vegas May 14 ,20 03 The Dissertation prepared by William A. Bloxsom E ntitled Modeling of the Reciprocating, Pneumatic Impact Hammer is approved in partial fulfillment of the requirements for the degree of Doctor of Philisophy in Mechanical Engineering_____ Examination Committee Chair Examination Committee Member Dean of the Graduate College Examination Committ^ Member _______ Examination Comijiittee Member é Æ Graduate College Faculty Representative PR/1017-52/1-00 11 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Modeling of the Reciprocating, Pneumatic Impact Hammer by William A. Bloxsom Dr. Douglas D. Reynolds, Examination Committee Chair Professor of Mechanical Engineering University of Nevada, Las Vegas The motion of the reciprocating, pneumatic impact tool, the air-driven piston inside the tool, the chisel mounted into the tool, and the specifically designed single degree-of-freedom spring-damper-mass test fixture were modeled with a M4TL4B computer code. The three tools modeled and evaluated experimentally were the Ingersoll-Rand IR-121 impact tool, the Sears Craftsman Medium Duty impact tool, and the ATSCO No.2 impact tool. The computer model of the accelerations of the tool and the test fixture mass were compared to the experimental data obtained on the actual test fixture by the three tools modeled. The correlation between the experimental data and the modeled data is high in both the time domain and the frequency domain. The computer model is modified to include an air spring vibration attenuation mechanism. The model is used to tune the attenuation device as well as predict the force produced by the chisel into the work piece and the vibration through the tool into the hand-arm of the operator. The computer program allows other attenuation methods to be modeled and evaluated prior to actual construction. Ill Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ABSTRACT........................................... iü LIST OF TABLES............................................................................... vi LIST OF FIGURES................................................... vii LIST OF SYMBOLS................................................................................................x ACKNOWLEDGEMENTS..................................................................................... xii CHAPTER 1: INTRODUCTION.............................................................................1 Health and Safety .........................................................................................1 Modeling .......................................................................................................5 The Text........................................................................................................9 CHAPTER 2: THE RECIPROCATING, PNEUMATIC IMPACT TOOL.............. 11 Tool Operation .................................................. ........................................ 11 Tool Anatomy ..............................................................................................15 CHAPTER 3: EXPERIMENTAL DATA........................................... 31 Test Stand..................................................................................................31 Instrumentation ................................................. 37 CHAPTER 4: THE COMPUTER MODEUNG..................................................... 43 Piston Modeling ...................................................................... 44 Initial Impact................................................................................................70 Permutation "A": Chisel impacting S-D-O-F Mass ....................................82 Permutation "B": Chisel Impacting Tool .................................................... 85 Permutation "C : No Collisions .................................................................. 87 Permutation "D": No Collisions; Tool, Chisel, s-d-o-f mass in contact 89 Permutation "E": Piston Impacting Chisel ................................................. 91 Analysis of Method .....................................................................................95 CHAPTER 5: RESULTS OF THE COMPUTER MODEL..................................102 Model Variables ........................................................................................ 102 Ingersoll-Rand IR-121 ............................................................................... 110 Sears Medium D uty .......................................... 116 ATSCO No. 2 ............................................................................................ 123 Chisel Comparison ................................................................................... 129 IV Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER 6: CONCLUSION AND SUMMARY................................................ 135 APPENDICES:....................................................................................................138 A: Free Vibration, Forcing Function Correlation ................... 138 B: Sensitivity of Harmonic Forcing Function ......................................... 151 C: MATLAB Code to Process Data ........................................................ 155 D: Selected Portions of the Modeling Code ...........................................162 BIBLIOGRAPHY............................................ 168 VITA.................................................................................................................... 178 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES Table 1 ACGIH recommended exposure limits for hand vibration ...... Table 2 Comparative masses of moving internal parts ........................ ..44 Table 3 Chart of relationships between piston location and force due to air pressure for Ingersoll-Rand IR-121 ........................ 49 Table 4 Chart of relationships between piston location and force due to air pressure for Sears Medium Duty .................................. 52 Table 5 Chart of relationships between piston location and force due to air pressure for ATSCO No. 2 .............................................55 Table 6: Displacements of Ingersoll-Rand and Sears Medium Duty pistons within cylinder and corresponding air pressure for one cycle .................................................................................. 58 Table 7: Input variables in MATLAB computer code .................. 104 Table 8: Static and dynamic deflections of s-d-o-f mass ............................. 109 VI Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES Figure 1 Ingersoll-Rand Impact hammer ........................................................15 Figure 2 Sears Craftsman Medium Duty