Patent ID: 6944932

Claim:
A method of knotting an end lacing terminal of a cord used for wrapping a generally toroidal coil of a dynamo-electric machine, by means of a lacing apparatus of the type comprising cord supply means, a lacing needle having a hook-shaped extremity and capable of rotating around its axis as well as of moving radially and axially relatively to said coil for engaging said cord and pulling it radially in order to form interlaced lacing rings wrapping said coil, and means for rotating said coil around its axis in synchronism with the movements of said needle, the method comprising the steps of: forming, upon completion of a lacing phase, a plurality of knotting rings in a chain-like arrangement on said end lacing terminal, by making the cord pass each time through a previously formed knotting ring or through a last-formed lacing ring, respectively, when a first knotting ring is being formed; and cutting the last knotting ring of said plurality; wherein said knotting rings are formed through the steps of: (a) once finished the lacing phase by means of a last radial movement of the needle from the inside of the coil toward the outside to form said last lacing ring, separating the synchronism between the rotation movement of the coil and the movement of the needle and stopping the rotation of said coil; (b) driving the needle in a first radial movement toward the inside of the coil, along a path equivalent to the needle path during said last radial movement, but in opposite direction; (c) hooking the cord, supplied by said cord supplying means, by means of the hook-shaped extremity of said needle; (d) driving the needle with the cord engaged in its hook-shaped extremity in a first radial movement toward the outside of the coil, along a path equivalent to the needle path during said first radial movement toward the inside, but in opposite direction, pulling the cord into said last lacing ring, causing its closing into a first knot lockup and forming a first knotting ring; (e) driving the needle in a second radial movement toward the inside of the coil, along a path equivalent to the needle path during said last radial movement, but in opposite direction; (f) hooking the cord, supplied by said cord supplying means, by means of the hook-shaped extremity of said needle; (g) driving the needle, with the cord engaged in its hook-shaped extremity, in a second radial movement toward the outside of the coil, along a path equivalent to the needle path during said second radial movement toward the inside, but in opposite direction, pulling the cord into said first knotting ring, causing its closing into a second knot lockup and forming a second knotting ring: (h) in case, repeating a given number of times the steps from (e) to (a); and (i) executing a cut in the last knotting ring and pulling the cord for extracting the free extremity, obtaining consequently a chain of knot lockups forming a self-locking knot.