| 摘要 |
<p>Anti-vibration sheathing 4 for cables such as deep water mooring lines, mast stays and bridge cables comprises integral helical strakes 5 and is produced by extrusion of the sheathing and strake onto a cable. Formation of the strake may be interrupted without interrupting formation of the sheath, such as by varying the height or thickness of the strake. The extrusion die may comprise a pair of relatively rotatable die members 35, 50 with respective grooves 32, 32 for forming the strake when axially aligned. The grooves may be misaligned by relative rotation of the die members 35, 50 to vary the thickness of the strake or stop its formation. Alternatively the strake can be varied by using a restriction member similar to a camera shutter. The helical form of the stake can be produced by rotating the die as the cable is fed axially through the extruder, and the pitch of the strake may be altered by varying the speed of rotation of the dies or the axial feed rate of the cable. The sheath may be provided with indicia formed by a laser following extrusion.</p> |
