screw axis


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screw axis

[′skrü ‚ak·səs]
(crystallography)
A symmetry element of some crystal lattices, in which the lattice is unaltered by a rotation about the axis combined with a translation parallel to the axis and equal to a fraction of the unit lattice distance in this direction.
References in periodicals archive ?
The first coordinate system, X'(x', y', z'), is fixed with its z' axis accordant with the axis of the screw, and x' y' plane is perpendicular to the screw axis.
A pellet bed moved along the screw axis as an element of the C-chamber, and it was dragged into the calendering gap.
Tenders are invited for Screw Axis Rear Sight Drg No.
The extrusion drum contains eight or ten small extruder barrels, parallel to the main screw axis.
The line is called instantaneous screw axis and denoted by I.
Right or left trapezohedrons occur in pairs at every other prism edge and actually define a two-fold screw axis (follow the blue line in Figs.
The drum contains 8 or 10 (depending on the model size) small extruder barrels, parallel to the main screw axis.
When the inclination angle between the screw axis and the timber plane is a = 45[degrees] and the friction between the interface of the members may be neglected ([mu] = 0), the eq (5), (11) and (16) may be rewritten for the above analysed failure modes as:
Cooling from the drive end allows melt to exit the machine along the screw axis rather than out the bottom.
A screw pulling-out method was used to characterize polymer behavior along the screw axis.
A conventional CNC milling machine can only cut in planes parallel to the screw axis, Spirex notes.