CALCULATION OF SCREW PROFILS

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

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