SINGLE-TURN SCREW ELEMENTS WITH REDUCED RIDGE LINE INCLINATION Russian patent published in 2014 - IPC B29C47/00 

FIELD: machine building.

SUBSTANCE: invention relates to screw elements for multiple shaft screw machines with screw shafts pairwise rotating in one direction and pairwise accurately cleaning each other by scraping, to the usage of such screw elements and to the method of plastic mass extrusion. Technical result is reached by the screw elements for multiple shaft screw machines with screw shafts pairwise rotating in one direction and pairwise cleaning each other by scraping, in each case only with one screw turn, with the interaxle distance a and the outer radius ra. The sum of ridge angles of a shaft pair is less than $$\text{2π}-\text{4arccos}\left(\frac{a}{\text{2}\cdot \text{r}a}\right).$$ In case of screw profiles having axial symmetry, none of the centres of the side circumferences lies on the perpendicular to the symmetry axis of the profile passing through the rotation centre. The screw element profiles in their sections consist of n circular arcs with the n being an integer number greater than 4. Each of the n circular arcs has a start point and a finish point, and the circular arcs in the start and finish points pass in one another tangentially.

EFFECT: provision of pressure increase comparable to known single-turn screw elements at lower shear impact induced on the processed material.

15 cl, 39 dwg