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