Improvements made to the processes and devices for the treatment of metal wires, more especially those used for constructions of prestressed concrete

摘要

969,191. Making wire; stretching at specified temperatures; altering physical structure. SOMERSET WIRE CO. Ltd. Sept. 13, 1960 [Sept. 26, 1959; Oct. 27, 1959], Nos. 23704/59 and 36295/59. Headings B3A, B3E and B3V. In apparatus for straightening wire ropes, strands &c. and increasing the proof stress or resistance to creep, the strands are continuously fed over a series of pulleys 10-15, Fig. 4, frictionally engaging the wire, each rotating at the same angular velocity but having progressively increasing diameters to progressively produce a predetermined strain, the so-strained wire being heated over a predetermined length to a temperature within the tempering range to produce a permanent elongation. In examples applied to high tensile steel wires having a carbon content Within the range 0.35 to 0.9% the tempering temperature is within the range 220- 500‹ C., and preferably within the range 250-380‹ C. With alloy steels the temperature may be as high as 600‹ C. The wires may be electrically heated along a loop 23 in the region of maximum strain and formed by the wire passing over a separately mounted remote pulley 14. Current is passed between the pulley 14 and the remaining block of pulleys 19 by brush contacts 32 or slip rings 35. The wire then passes through a cooler 36, Fig. 3, before leaving the loop 23 over pulleys 16-18 which have successively smaller diameters which reduce the tension in the wire before it passes to winding and reeling drums (not shown). The wire may be pulled directly from a stranding machine through the apparatus, solely by the winding and reeling drums or these may be coupled through chains or gears for driving the pulley system. Specifications 748,357 and 969,192 are referred to.