Profile correction factor

[pardal]

Hi all gear people.
Hope you can help me.
I have to draw a internal splined hub
I know how to do the profile in real involute function
Inv alfa= tan alfa - alfa [rad]
having thoot ,module and pressure angle all in Metric.
But here is the problem : the spec chart states that the
profile shall be corrected by a -0.1124 coeficient.
How I do use such coeficient.
Thanks in advance
k281969@hotmail.com

Pardal

 

[gearguru]

pardal,
the gear correcion factor ("x" in metric standards) controls (next to some other features) the thickness of the tooth.
You can visualize it like this:
If you cut the gear using the standard metric rack (module m, addendum = m, dedendum = 1.25*m, pressure angle = alpha)
and you locate it so, that the reference line on the rack is tangent to the pitch circle of the gear (which is d=m*z; z is no of teeth) then you create gear with tooth thickness=tooth space=1/2 of the pitch = 0.5*PI*m (it is measured as an arc on the pitch circle)
If you want thicker tooth, you move the rack out of the gear. If thinner, then you locate te rack's pitch line below the gear's pitch circle.
How much you move it is described by your "x".
You simply calculate m*x and this is the value how much the rack moved. Positive x creates thicker tooth, and vice-versa.
Hope this helps a little. Ask for more if you need!
gearguru