CALCULATION OF SCREW PROFILS

 

Initial Situation

Used screws

* Wears out Surface

* Edge contacts with cracks

Aim:

Screws with crack-free edge contacts based on the profils of the used screws

Procedure

* Determination of the profil of an used screw

* Calculation of the two-way screw

* Calculation of the screw helix

Determine the edge profile of an used screw

* Digitilize the screw profil

* Determine the x-y-coordinates of the outline points

* Eliminate the edge disruptions

* Detemine the function of the edges

Calculation

Assure a steady transformation

* Rule of the comon normal Calculation of the Helix

* Determine the Helix of the main screw

* Determine the opposite Helix

Assure a steady transformation

Rule of the comon normal

vn1 = vn2 <= > w 1 rb1 = w 2 rb2

=> w 1/ w 2 = rb2 /rb1 = const.

Condition: the comon normal of engagement (red) have to go in every contact point through the contact point C of the pitch circles

Calculation of the Helix

* Measurement of the screw length L

* Measurement of the total rotation along the screw F

* Profilrotation per length F L = F / L

* Transformation R

* Profilrotation of the opposite screw F LG = F L / R

Results

Calculation of the opposite profil and the Helix

* The blue profil is the digitilized and straightened profil

* The red profil is calculated from the blue profil