1. A Study of Fixture Layout and Clamping Force for a Ti-6Al-4V Disk in a Vertical Turning Lathe Numerically Controlled Machine
Maureen Fang
Sept 17, 2009

2. Overview Vertical Turning Lathe (VTL) Machine Fixture-Disk Assembly
Cutting Forces
Finite Element Models in ANSYS
Initial Fixture Layout
Deflections within Disk
Questions

3. Vertical Turning Lathe (VTL) Machine

4. Fixture-Disk Assembly
Inner Diameter=0.457m (18 in)
Outer Diameter=0.508m (20 in)
Height=0.0508m (2 in)
Clamp
Locator
Plate

5. Machining an Outer Diameter
Cutting Tool

6. Cutting Forces Orientations

7. Cutting Forces Calculation Flow Diagram

8. Input Variables
Tool Geometry
Machining Parameters

9. Cutting Forces Tangential Force Orthogonal Cutting
Results are generated by Matlab codes for both oblique and orthogonal cutting
Orthogonal cutting has only two cutting forces components
Tangential force is the dominate component.
Tangential Force
Orthogonal Cutting

10. Finite Element Model in ANSYS
Number of elements
32000
Number of Nodes
38720
Degree of Freedom per Node 6
Type of Elements
Brick
Material of Workpiece
Ti-6Al-4V
Modulus of Elasticity
110 GPa
Poisson Ratio
0.34

11. Clamps, Locators, and Cutting Forces applied to Initial Fixture Layout
Locators are constraint in 3 axis
Clamping Force = 1500N

12. Deflections within a Finish Cut
The “U” shape curve presents the magnitude of deflection changes as the cutting tool travels from the top to the bottom surface of the disk.
The displacement vector sum is largest at the top.
The subsequent models will have the cutting forces applied at the top surface.

13. Key Locations to Represent a Dynamic Machining Process
ANSYS model is static analysis of a dynamic process. Therefore, selected cases are used to represent snap shots of the overall machining process.
Point A, B, and C are key locations of disk where cutting forces have been applied, as disk rotates.

14. Displacement Vector SumB

15. Displacement Components
Z-component = axial direction
Y-component = circumferential direction
X-component = radial direction
Clamp and locator is aligned with cutting forces at Key Location “B”

16. Contour Plots from ANSYS

17. Questions