. The Bell System technical journal . c head wire si raigtiicniiig niachiiic. 868 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1954 OBSERVATIONS ON WIRE STRAIGHTENING The straightening operation affects some physical properties of thewire. Tensile strength is reduced about 10 per cent while elongation isincreased around 50 per cent. The diameter of the straightened Avire isusually from to per cent greater than that of the raw wire AAithcommensurate loss in wire length. Both straightness and twist appear tobe dependent in large part upon the contours of the die blades. Thusfar these contours
. The Bell System technical journal . c head wire si raigtiicniiig niachiiic. 868 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1954 OBSERVATIONS ON WIRE STRAIGHTENING The straightening operation affects some physical properties of thewire. Tensile strength is reduced about 10 per cent while elongation isincreased around 50 per cent. The diameter of the straightened Avire isusually from to per cent greater than that of the raw wire AAithcommensurate loss in wire length. Both straightness and twist appear tobe dependent in large part upon the contours of the die blades. Thusfar these contours have been determined by trial and error on the ad-justable die block straightener, although .general relationships, especiallywith respect to wire size, are becoming evident. It is expected that fur-ther study and experience wi\\ establish bases on which contours can becalculated with accuracy. Twist imparted to the mre by the rotating action of the spindle hasbeen found difficult to measure. What is referred to as twist is actually. Fig. 6 — Double spindle showing slots and conipU-uuni oi l wo sets of die blades. radial distortion of the wire about its longitudinal axis resulting frompartial release of internal stresses remaining in the wire after straighten-ing. Further release of internal stresses may occur when the wire endsof the twin wire comb are formed before welding, in which event misloca-tion of contacts will result. Fig. 7. This is objectionable from the stand-point both of subsequent manufacturing operations and of relay per-formance. The internal stresses are caused by the crank action appliedto the wire surface while it is passing between the die blades in therotating spindles. Internal stress which is not apparent until after itsrelease, as by forming, has been designated as residual twist. A rough approximation of the amount of residual twist in wire canbe obtained by measuring w^hat has been termed apparent twist is the amount of visible rotat
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
