Sylvester Reu Presentation

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The results of two months of research over the summer. This is my first presentation on the subject.

The results of two months of research over the summer. This is my first presentation on the subject.

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  • 1. Undergraduate Research Experience Deformation Machining
      • Dylan Sylvester
      • Dr. Bethany Woody
      • Dr. Scott Smith
  • 2. Single Point Incremental Forming No expensive tooling Simple 3-axis Machine Sheet metal is ‘pushed’ to shape Thin Structure Machining Monolithic Pieces Reduced Assembly cost What is deformation machining?
  • 3. Deformation Machining Advantages Create geometries otherwise impossible Potential for weight and cost reduction Eliminate the need for expensive 5 axis machines Extra material in the radius = added weight
  • 4. Deformation Machining Advantages Create geometries otherwise impossible Potential for weight and cost reduction Eliminate the need for expensive 5 axis machines
  • 5. Deformation Modes
    • Bending
    • Walls
    • Forces are perpendicular to forming axis
  • 6.
    • Stretching
    • Floors
    • Forces are parallel to forming axis
    Deformation Modes
  • 7. Process Requirements
  • 8. Previous Research
  • 9. Process Parameters Grain direction
    • Tool path
    • Depth of Cut
    • Step Size
    • Arc vs. no arc
    • Forming Speed
    • Linear feed rate
    • Spindle speed
    Surface Finish, Final Geometry, and Cracking
  • 10. Tool Path : Wall Forming
  • 11. Tool Path : Floor Forming
  • 12. Current Research
    • Changing parameters and their effects
      • Forming Speed
      • Spindle Speed
      • Tool Path
    SEM Analysis of Cracking
    • Forming forces
      • Effects of forming direction
      • Effects of wall thickness
    • Alternate Materials
      • Copper
      • Stainless Steel
  • 13. Forming Speed and Spindle Speed
    • Use similar walls, tool path, and grain direction
    • Change only linear feed rate
    • Measure spring back – when metal returns to its original shape after undergoing stretching
    Part Number Wall Number Material Bending Axis Wall Thickness (in) Wall Height (in) Wall Length (in) Feedrate (ipm) Max Horiz Step Size (in) Tool Size Diam. (in) Desired Angle Bending Angle achieved Angle Spring back Percent Percent off Desired Visible Cracks Mastercam File Name Spindle Speed (rpm) Lube W5 A AL7050-T7451 ST 0.04 0.85 1.5 30 0.04 0.5 - 45 43.561 3.20% - N W5 0 Lithium W5 B AL7050-T7451 ST 0.04 0.85 1.5 40 0.04 0.5 - 45 44.447 1.23% - N W5 0 Lithium W5 C AL7050-T7451 ST 0.04 0.85 1.5 50 0.04 0.5 - 45 42.959 4.54% - N W5 0 Lithium W5 D AL7050-T7451 ST 0.04 0.85 1.5 60 0.04 0.5 - 45 44.192 1.80% - N W5 0 Lithium W5 E AL7050-T7451 ST 0.04 0.85 1.5 70 0.04 0.5 - 45 43.846 2.56% - N W5 0 Lithium W5 F AL7050-T7451 ST 0.04 0.85 1.5 80 0.04 0.5 - 45 44.169 1.85% - N W5 0 Lithium W7 A AL7050-T7451 ST 0.04 0.85 1.5 30 0.04 0.5 - 35 32.532 7.05% - N W7 0 Lithium W7 B AL7050-T7451 ST 0.04 0.85 1.5 40 0.04 0.5 - 35 33.354 4.70% - N W7 0 Lithium W7 C AL7050-T7451 ST 0.04 0.85 1.5 50 0.04 0.5 - 35 33.099 5.43% - N W7 0 Lithium W7 D AL7050-T7451 ST 0.04 0.85 1.5 60 0.04 0.5 - 35 33.095 5.44% - N W7 0 Lithium W7 E AL7050-T7451 ST 0.04 0.85 1.5 70 0.04 0.5 - 35 33.624 3.93% - N W7 0 Lithium W7 F AL7050-T7451 ST 0.04 0.85 1.5 80 0.04 0.5 - 35 33.747 3.58% - N W7 0 Lithium
  • 14. Forming Speed and Spindle Speed
    • Forming Speed only effects small angles
    • In ST and LT directions, no cracking was visible on the surface
    • Minimal increase in forming forces compared to slow form rates
  • 15. Forming Speed and Spindle Speed
    • Cause spindle to rotate based on linear travel direction
    • RPM depends on linear feed rate and radius of tool
    • Contact point changes over time
    • Constantly changing spindle speed
    • Smudged or scaly appearance
  • 16. Forming Forces
    • Using dynamometer (left) forces were measured while forming
    • Calibration using known weights and measuring the output along with impact hammer
    • Pieces securely attached to dynamometer
    • LT, ST, and longitudinal directions measured for .04” thick walls in aluminum
    Y X Z
  • 17. Forming Forces – Long Transverse
      • Largest force in Y direction – about 400 N
      • Cracking around 175 seconds – dramatic loss in force
      • Changing X direction caused alternating positive and negative force
  • 18. Forming Forces – Short Transverse
      • Largest force in Y direction – about 380 N
      • High Z forces near end of form
      • Changing X direction caused alternating positive and negative force
  • 19. Forming Forces - Longitudinal
      • Largest force in Y direction – about 380 N
      • Cracked halfway during form
  • 20.
    • .02” Thick Wall
    • LT Forming direction
    • A few visible surface defects, however no noticeable cracks
    SEM Analysis
  • 21.
    • Many smalls cracks aren’t visible without magnification
    • A relatively large crack is often surrounded by many smaller cracks
    • Many small voids created along bend path
    SEM Analysis
  • 22. Alternate Materials Copper
    • Same tool path as aluminum yields visibly curved wall
    • Spring back results differ from aluminum
    Part Number Wall Number Material Bending Axis Wall Thickness (in) Wall Height (in) Wall Length (in) Feedrate (ipm) Max Horiz Step Size (in) Tool Size Diam. (in) Desired Angle Bending Angle achieved Angle Spring back Percent Percent off Desired Visible Cracks Mastercam File Name Spindle Speed (rpm) Lube W11 A Copper - 0.04 0.85 1.5 10 0.04 0.5 - 20 19.92 0.40% - N Copper Wall 0 Lithium W11 B Copper - 0.04 0.85 1.5 10 0.04 0.5 - 25 24.538 1.85% - N Copper Wall 0 Lithium W11 C Copper - 0.04 0.85 1.5 10 0.04 0.5 - 30 29.527 1.58% - N Copper Wall 0 Lithium W11 D Copper - 0.04 0.85 1.5 10 0.04 0.5 - 35 34.7 0.86% - N Copper Wall 0 Lithium W11 E Copper - 0.04 0.85 1.5 10 0.04 0.5 - 40 39.513 1.22% - N Copper Wall 0 Lithium W11 F Copper - 0.04 0.85 1.5 10 0.04 0.5 - 45 44.617 0.85% - N Copper Wall 0 Lithium
  • 23. Alternate Materials Stainless Steel
    • Same tool path as aluminum yields visibly curved wall
    • Higher feed rate has little effect on spring back
  • 24. Ongoing Research
    • Residual stress measurements at NIST and correlation with cracking
    • Further analysis of forming parameter in regards to cracking
    • Refinement of tool path to create straight walls regardless of material
    • Continue alternate material testing along including complex shapes
    • Further SEM and stereo microscope analysis