Abstract :
Autocollimators
are used to detect small misalignments. If a parallel beam of light is projected
from the collimating lens and if a plane reflector R is set up normal to the direction
of the beam, light will be reflected back along the same path and light will be
brought back to focus exactly at the position of the light source.
If the reflector
is tilted through a small angle (Theta) the parallel beam will be reflected through
twice the angle (2?) and would be brought to focus in the same plane as the light
source but to one side of it. The image will not coincide but there will be a distance
equal to focal length times the angle of reflection (2f??) where f is the focal
length of the collimating lens.
The distance
between the reflector and the lens has no effect on the separation between the
source and the image. For high sensitivity, a long focal length is required. Although
the distance of the reflector does not effect the reading, if it is moved too far
back, reflected rays will miss the lens completely and no image will be formed.
Element by Element
Inspection of Gear: Laborious, useful in error analysis, can’t be used by the gear manufacturers.
Tooth
thickness measurement
Base
pitch measurement
Composite Error
Checking: Used in Gear Inspection by conducting only one test
Parkinson
Gear Tester
Thread Inspection
- Terminology
Pitch
- It is the distance measured parallel to the axis between the corresponding points
on adjacent surfaces in the same axial plane.
Lead
- It is the axial distance advanced by the thread in one revolution. Lead is
equal to the same multiples of pitches as the number of starts.
Included
angle - It is the angle between the flanks of the thread measured in an axial
plane.
Pitch
diameter - It is the diameter of tee imaginary coaxial cylinder which intersects
the surface of the thread in such a manner that the intercept on the generator of
the cylinder is equal to half the pitch.
Major
Diameter - It is the diameter of imaginary coaxial cylinder that just touches
the crests
Minor
Diameter - It is the diameter of imaginary coaxial cylinder that just touches
the
Roots.
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