Principles of Rapid Machine Design - University of Utah

1 Principles of Rapid Machine DesignbyEberhard , Advanced Manufacturing SystemsBrunel University , , MaschinenbauUniversit t Stuttgart, 1996 SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERINGIN PARTIAL FULFILLMENT OF THE DEGREE OFDOCTOR OF PHILOSOPHYat theMASSACHUSETTS INSTITUTE OF TECHNOLOGYJune 2000 2000 Massachusetts Institute of TechnologyAll rights reservedSignature of Author .. Department of Mechanical EngineeringMay 19, 2000 Certified by .. Professor Alexander H. SlocumProfessor of Mechanical EngineeringThesis SupervisorAccepted by .. Professor Ain A. SoninProfessor of Mechanical EngineeringChairman, Committee on Graduate Students23 Abstract.

2 7 Acknowledgments .. 9 Chapter .. Overview .. Summary of Contributions .. 13 Chapter Principles .. Computer Aided Concept Generation .. Background .. Overview .. Concept Generation .. CAD Component Libraries .. Component Selection Process .. Stiffness Budget .. First Pass Selection .. Second Pass Selection .. Bearing Calculations .. Ballscrew and Drive Motor Calculations .. Concept Selection Process .. First Round Elimination - Fulfillment of Functional Requirements.

3 Second Round Elimination - Visual Inspection .. Third Round Elimination - Analytical Analysis .. Fourth Round Elimination - FEA Analysis .. Finite Element Modeling Techniques .. Basic Facts About FEA .. Basic FEA Elements .. Modeling Bearings .. Modeling Plates as Shells .. Constraints .. Performance and Accuracy .. Conclusion .. 71 Chapter Principles .. Fabricated Structures .. Kinematically Defined Machine Supports .. Standard Machine Elements .. Linear Rails.

4 Ballscrews .. Replication .. Reference Edge .. Replicated Joints .. 83 Chapter .. Mathematical Models .. Material Damping .. Damping in Bolted Joints and Bearings .. Active Damping .. Constrained Layer Damping .. Background .. Principle of Constrained Layer Damping .. The Split Tube Design .. Concrete Cast Damper .. Reinforced Concrete Cast Damper Design .. Round Core Concrete Cast with Multiple Reinforcement .. Concrete Cast with Interlocking Constraining Layers.

5 106 Chapter Experiments .. Building the Dampers .. Split Tube .. Concrete Core Damper .. Concrete Core Cast with Reinforcement .. Concrete Mixture .. Material Cost .. Experimental Setup .. Damping Calculations .. Experimental Data .. Test Results .. Conclusion .. 123 Chapter Study - STG .. STG .. Overall Machine Concepts .. First Round Elimination - Fulfillment of Functional Requirements .. Second Round Elimination - Visual Inspection .. Result of First and Second Round Elimination.

6 Third Round Elimination - FEA Analysis .. Final Round Elimination - Team Discussion .. STG Base .. STG Base Concepts .. Design Optimization .. STG Gantry .. STG Gantry Concepts .. STG Modal Analysis .. Rigid Body Modes .. Actual Modes .. Recommendations .. 162 Chapter Study - TubeMill .. Error Budget .. Overall Machine Concepts .. Base Concepts .. First Round Elimination - FEA Analysis .. Second Pass Elimination - Global Sensitivity Study .. TubeMill Gantry Concepts.

7 Design Optimization of Gantry .. 181 Nomenclature .. 183 References .. 1856 Principles of Rapid Machine DesignbyEberhard BambergSubmitted to the Department of Mechanical Engineeringon May 19, 2000 in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophyat the Massachusetts Institute of TechnologyABSTRACTF ollowing a continuing industry wide trend that began many years ago, Design -to-manu-facturing times for all kinds of products are getting increasingly shorter. The productionequipment industry is no exception to this development and needs to respond thesis presents a novel approach to conceptual Design as part of a Rapid machinedesign initiative.

8 Solid model CAD systems and advanced engineering tools are used dur-ing the early Design phase to generate realistic concepts of designs for manufacturingequipment. Concept evaluation is done very effectively through use of advanced analysistools such as Finite Element Analysis. Core elements of this initiative are: create reason-ably detailed concepts with 3D CAD systems, analyze concepts analytically if possible orthrough use of finite element methods if necessary, and build designs from fabricatedstructures so there are no tooling times or costs, resulting in short Design -to-manufacturetimes.

9 In addition, to enable this methodology to be realizable, a new Design for structuraldamping is presented which helps to reduce Design uncertainty caused by vibration. Thenovel constrained layer damping Design achieves the same or better levels of damping at afraction of the cost of existing studies of two fabricated Machine tool structures are used to illustrate this new FEAbased concept evaluation technique. The first study illustrates this Design process in whichthe new approach to conceptual Design led to a fundamentally new way of designingmachine tool structures. A second study presents an optimization process where FEA isused to select, size and position structural members of a truss-like Machine Committee:Prof.

10 Alexander H. Slocum (Chair)Prof. Sanjay SarmaProf. Samir NayfehDept. of Mechanical Engineering, Massachusetts Institute of Technology8 ABSTRACT9 ACKNOWLEDGMENTSThis research was supported by Bill Silberhorn and Bud Webber of the Elk Rapids Engi-neering Corporation, a division of Star Cutter Company. I am grateful to Stan Ruskowskifor his open mind towards new ideas and turning them into an actual Machine special thanks go to my friend and advisor Alex Slocum for his guidance and neverending inspiration. Snowboarding wouldn t be the same without him. Prof. Sanjay Sarmafor his constructive criticism on writing this thesis and Prof.