Device and method for forming end of coiled spring

A coil spring end forming apparatus comprising:

• a pair of horizontally disposed parallel rollers that rotate in the same direction and on which is mounted a cylindrical coil-shaped semi-formed spring that tends toward formation of a pigtail portion at a first end thereof;
• a mandrel, which is a cylindrical body having an outer diameter smaller than an inner diameter of the semi-formed spring, that is horizontally disposed near one end of the parallel rollers;
• a stopper that is provided coaxially and integrally with the mandrel and receives the first end of the semi-formed spring, wherein a relative position of the stopper and the mandrel does not change;
• a clamp jig that is provided adjacent to the stopper so as to be movable toward or away from the mandrel, that forms a clamp portion with the mandrel and the stopper, and that holds the first end of the semi-formed spring in cooperation with the mandrel;
• and
• a pusher that pushes a second end of the semi-formed spring toward the stopper on the parallel rollers,
• wherein the clamp portion is configured such that in a state in which the axis of the mandrel is positioned between axes of the parallel rollers and an axis of the semi-formed spring, the clamp portion holds the first end of the semi-formed spring at an inner side of a triangle formed by the axes of the parallel rollers and the semi-formed spring, and rotates around the axis of the mandrel in a winding direction of the semi-formed spring to form the pigtail portion at the first end of the semi-formed spring, and
• the coil spring end forming apparatus is configured such that no compression force perpendicular to an axis of a filament of the semi-formed coil spring is applied on the semi-formed coil spring between the pusher and the mandrel while forming the pigtail portion.