Method and system for forming strings of pocketed coil springs with traction mechanism

A method of forming a string of pocketed coil springs comprising the steps of:

• feeding a supply of fabric having first and second generally parallel plies of the fabric;
• inserting a series of compressed springs between the first and second plies;
• joining the first and second plies together to form a longitudinal seam proximate free edges of the first and second plies opposite from the longitudinal fold line;
• allowing the springs to at least partially expand within the fabric so that a longitudinal axis of each of the springs is generally perpendicular to the longitudinal seam of the fabric;
• engaging the fabric with a plurality of moving projections to thereby control the movement of the fabric;
• and
• forming a transverse seam in the fabric between adjacent springs to thereby enclose each of the springs within a fabric pocket.

A system for forming a string of pocketed coil springs, each of the springs being enclosed within a pocket formed of fabric, the system comprising:

• a spring insertion station at which compressed springs are individually inserted between first and second plies of the fabric;
• a longitudinal seam forming station located downstream from the spring insertion station, the longitudinal seam forming station joining the first and second plies of the fabric together to form a longitudinal seam proximate free edges of the first and second plies;
• a spring expansion station located downstream from the longitudinal seam forming station, the spring expansion station permitting the springs to at least partially expand between the first and second plies with a longitudinal axis of each spring being generally perpendicular to the longitudinal seam;
• a transverse seam forming station located downstream from the longitudinal seam forming station, the transverse seam forming station forming a transverse seam in the fabric to separate each pair of adjacent springs and thereby enclose each of the springs within a fabric pocket when inserted therein;
• and
• a transport station which advances the fabric and springs contained therein through the respective stations;
• wherein the spring expansion station further comprises at least one moving member having a plurality of projections engaging the fabric to thereby assist in movement of the fabric and springs contained therein.

A system for forming a string of pocketed coil springs, each of the springs being enclosed within a pocket formed of fabric, the system comprising:

• a spring insertion station at which compressed springs are individually inserted between first and second plies of the fabric folded about a longitudinal fold line;
• longitudinal seam forming station located downstream from the spring insertion station, the longitudinal seam forming station including a cooperating thermal weld head and anvil to thermally weld the first and second plies of the fabric together to form a longitudinal seam proximate free edges of the first and second plies opposite from the longitudinal fold line;
• a spring expansion station located downstream from the longitudinal seam forming station, the spring expansion station including a pair of rotating members on opposite sides of the springs within the fabric to permit the springs to at least partially expand between the first and second plies so that a longitudinal axis of each spring is generally perpendicular to the longitudinal seam;
• a plurality of nibs projecting from at least one of the bands to engage the fabric;
• a transverse seam forming station located downstream from the spring expansion station, the transverse seam forming station including a cooperating thermal weld head and anvil to thermally weld a transverse seam in the fabric between each pair of adjacent springs to thereby enclose each of the springs within a fabric pocket when inserted therein;
• and
• a transport station which advances the fabric and springs contained therein through the respective stations.