NEAR KINEMATIC CONSTRAINT

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NEARKINEMATIC CONSTRAINT
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Quasi-Kinematic (QKC) alignment

• QKC characteristics
• Arc contact
• Submicron repeatability
• Stiff, sealing contact
• Less expensive than KCs
• Easier to make than KCs

Spherical Protrusion
Groove Seat
Side Reliefs

• QKC Function
• Ball groove comply
• Burnish surface irregularities
• Elastic recovery restores gap

Feature Height, mils
Distance along Cone Face, inches
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Details of QKC element geometry
PAIRS OF QKC ELEMENTS
OR
ASSEMBLED JOINT
TYPE 2 GROOVE MFG.
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Which variation of QKC to use

• Design A Design B
• In Design A, Peg deforms on edge -gt reduced
  repeatability

OR
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QKC methods vs kinematic method
Components and Definitions
Relief
Relief
Cone Seat
Ball
Groove Surface
Peg Surface
Contact Point
Force Diagrams
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Modeling QKC stiffness
Resultant Forces ni Fi
Applied Loads Fp Mp
Deflections d -gt Dr
Relative Error
Geometry Material
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QKC contact mechanics
MECHANICS Use Rotating Coordinate System
Assume Sinusoidal Normal Distance of Approach
Obtain Contact Stress Profile as Function of
Above Integrate Stress Profile in Rotating CS
thru contact
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Example DuratecTM assembly

• Characteristics
• Ford 2.5 3.0 L V6
• gt 300,000 Units / Year
• Cycle Time lt 30 s

Rough Error Budget
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Example Assembly of DuratecTM block bedplate
COMPONENTS
ERROR
ASSEMBLY
de MAX 5 microns
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Bearing assemblies in engines
Block
Block Main Bearing Half
Crank Shaft Journal
Piston
Bedplate Main Bearing Half
Crank Shaft
Bedplate
Main Bearing Halves
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Detail of DuratecTM QKC element placement
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Results of DuratecTM QKC Research
MANUFACTURING
DESIGN
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Engine assembly performance
(Range/2) 1.35 mm
(Range/2)AVG 0.65 mm
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