GB262775A - Improvements in apparatus for making edgewound coils - Google Patents

Abstract

262,775. Whittingham, G. H. Dec. 11, 1925, [Convention date]. Coiling; dies.-Open-wound helical coils for electric resistances &c. are coiled in a succession of steps in a machine of lathe form, the length of helix produced being longer than that of the mandrel employed. The main part c, Fig. 3 of the two piece helical die employed is mounted in a counterbored recess of the holder 10 carried by the saddle and positioned axially by backing- up screws. Both die parts are hardened and cooperate with a hardened bar 13 which guides the strip into the die and is recessed both into the holder and into the cover 16 which carries the other die part e, and is secured by a row of bolts below the bar. The other holes in this holder receive bolts which pass through into tapped holes 19 in tha cover for adjusting the pressure of the die on the strip. Initially these bolts are slacked back clear of the slit in the die and the strip is introduced at s. The end is bent over and wedged at 20 into the faceplate of the machine. The spindle is rotated to form the first part turn and the cover bolts are then returned to place and adjusted. The mandrel 3 is secured in the spindle, passes through the die and is guided in the tailstock. The saddle is traversed by the leadscrew as coiling proceeds up to the full length permitted by the bed. The spindle is then reversed for one or two rotations to free the grip of the coil on the mandrel and the saddle is racked back compressing the coil into close formation f, a further length f<2> is then coiled as before and this is compressed and so on until the mandrel is almost completely filled. The strip is then severed close to the die the coiling is completed right up to the severed end and the tailstock and saddle are moved outwards along the bed clear of the mandrel to release the coil which discharges itself almost completely from the mandrel by virtue of the elastiticity of the strip.