Spring coil and spring assembly

A spring assembly for a generally rectangular mattress innerspring unit comprising:

• a plurality of spring coils each having a spiral spring coil body with two ends, a terminal convolution at each end of said spring coil body, at least one of said terminal convolutions having a C-shape with a first and a second offset portion which are opposed to each other, and a third offset portion joining said first and second offset portions, said first offset portion having a free end, all of said offset portions being approximately in the same plane,
• said second offset portion having one end joined to said third offset portion with the other end being joined to said spiral spring coil body by a connecting segment extending in the same plane as said terminal convolution, said connecting segment forming a gradient arm that is adjustable in length in manufacture to vary the compression and thereby the firmness of the spring coil, said gradient arm being integrally connected with said spiral coil body at a shoulder,
• said spring coils being disposed on substantially parallel axes with said terminal convolutions on respective coil ends being generally co-planar and arranged in side by side relation in a plurality of parallel rows and parallel columns,
• first and second offset portions of adjacent spring coils overlapped with each other in said rows, a plurality of cross-helical springs extending along said columns and coiled about said overlapped first and second offset portions,
• a border wire surrounding a perimeter formed by said spring coils, and
• offset portions of spring coils at the ends of said rows and columns being joined to said border wire.

A spring assembly for a mattress innerspring unit comprising:

• a plurality of spiral spring coils, each spring coil having a body with two ends, a terminal convolution at each end of said spring coil body, at least one of said terminal convolutions having a first and a second offset portion which are on opposite sides of said spring coil body and parallel to each other, and a third offset portion joining said first and second offset portions,
• said first and second offset portions having a main segment that is generally straight, with said straight segment extending into a shoulder at each end thereof, each said shoulder having an inside and an outside,
• said spring coils being disposed on substantially parallel axes with said terminal convolutions on respective coil ends being generally co-planar and arranged in side by side relation in a plurality of parallel rows and parallel columns,
• first and second offset portions of adjacent spring coils being overlapped with each other in said rows,
• a plurality of cross-helical springs extending along said columns and coiled about said overlapped first and second offset portions, said cross-helical simultaneously engaging said outside shoulders of one of said overlapped offset portions to prevent rotation of said adjacent spring coils.

A spring assembly for a generally rectangular mattress innerspring unit comprising:

• a plurality of spring coils having a spiral spring coil body with two ends, a terminal convolution at each end of said spring coil body, at least one of said terminal convolutions having a first and a second offset portion which are opposed to each other, and a third offset portion joining said first and second offset portions, all of said offset portions being approximately in the same plane.
• said third offset portion of each said spring coil having a stepped segment formed thereon, said stepped segment having a major part that is substantially straight and extending generally perpendicular to said first and second offset portions and spaced radially outwardly from said spring coil axis, short parts extending from the ends of said straight part, said short parts joining with remaining straight segments of said third offset portion which extend generally parallel to said staight part and which join with respective ends of said first and second offset portions,
• a border wire surrounding a perimeter formed by said spring coils, and
• a border wire helical coiling around and closely embracing said straight part and said straight segments of said third offset portion adjacent said border wire to hold said third offset portion against rotation about said border wire.