2.72 design lab meeting - mit
TRANSCRIPT
2.72 Design Lab Meeting02/23/09
Group 4
Purpose
To give progress on the project
To give details of work to date, and future plans
To ask questions regarding other parts
Meeting Outline
ScheduleUpdate on Shaft Fatigue AnalysisDesign & Modeling, HTM, FEA
ShaftHousingEnd CapCrossfeed FlexureLead Screw Flexure
Measurement: Spindle ErrorFinancial UpdatesQuestions
Gantt Chart by 04/06
Fabrication
- Spindle Shaft- Spindle Housing- Housing end caps- Cross-feed flexure - Lead-Screw flexure
Error Models
- Spindle Error- Flexure Error- Drive Error
To-Do
CMM for crossfeed flexure, lead screw flexure
Design and manufacture lead screw drive
Motor Mount, drive system (gear vs. belt drive)
Documentation
Process plans with 2D Cad drawing and 3D rendering
- Spindle Shaft- Spindle Housing- Housing end caps- Cross-feed flexure - Lead-Screw flexure
Shaft Fatigue Analysis
Endurance Limit: Se = 188MPa*
Fatigue Strength: Sf = 269 MPa (70,000 cycles)
Expected Life: N = 5 billion cycles
Safety Factor: n = 4.5
(*: see MathCad file for various factors and calculations)
Design & ModelingSpindle: Shaft
Design & ModelingHousing
Design & ModelingEnd Cap
Design & ModelingSpindle Assembly
Design & Modeling INSERT PICTURE
Crossfeed Flexure
FEA: Crossfeed Flexure
Static analysis- Dimension flexure with 30% stress factor of safety
Dynamic analysis- Check first 3 modal frequencies, ensure not too low
Static Analysis
Dynamic Analysis - First Vibration Mode
Dynamic Analysis - Second Vibration Mode
FEA Results
Design & ModelingINSERT PICTURE
Lead Screw Flexure
MORE FEA STUFF FROM EVAN
Measurement
Measured spindle error using Donaldson Ball Reversal Method
Error Measurement Results
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Ranges from -15.1 to -40.1 microns (∆= 25 microns)
Comments: Nut loosened. Double nuts?
Financial: Orders & Budget
Bearing Number: LM12749 LM12710$6.77 EachTimken Tapered Roller BearingsShaft diameter 55/64”Outside Diameter 1-25/32”
Part Number: 9712K92 $14.38 per Pack of 12Belleville Disk SpringsGrade 1074 High-Carbon SteelMinimum Inside Diameter: 0.880"Maximum Outside Diameter: 1.750"Thickness: 0.085"
Financial: Orders & BudgetPart Number: 89535K31 $28.33 EachRail Length 6'Diameter 5/8"Multipurpose Stainless Steel 304/304L
Part Number: 6391K247 $0.98 EachBusing Length: 3/4"OD: 3/4"ID: 5/8"SAE 841 Bronze
-Ordered: 12 tapered roller bearings, 1 pack of 12 disc springs, 1 six foot steel rail,3 bushings = $126.89-Needed: 1 six foot steel rail, 15 busings, Between 6-12 shaft nuts (estimated $1Each) = $55
Budget: $200Used: $127Needed: $55Extra: $18