Abstract: The stranded wires helical spring is normally made up of 2 to 7 carbon steel wires that are tied up to form a strand which is then twisted to form a helical spring. It is extremely important to remain consistent tension of individual wires during reeling to assure the quality of a spring. The mathematic models on center lines of wires are put forward. The dynamic tension theory of individual wires is derived. The research concludes that the quality of a spring is related to the wire quality, as well as the velocity of reeling and the moment of inertia that causes the generation of tensional force on individual wires. A scheme on acquiring and controlling the reeling technical parameters of the spring is proposed. According to case study, high reject rate of the stranded wires helical spring is resulted from tension control error up to 20% by system inertia during reeling. The problem is solved by reducing the maximum velocity of the reel, which improves spring qualified rate for tension control error down to 0.6%.

Key words: Dynamic tension, Mechanical model, Reeling techniques, Stranded wires helical spring