Mattress spring core with open ended coils

A spring core for a mattress, comprising:

• a plurality of identically configured helical circular coil springs (10) each made of a single, uninterrupted piece of wire having upper and lower final windings disposed in planes perpendicular to a spring axis, said springs being connected with each other at their final windings (11) by spiral shaped connecting elements (30) lying in said planes, each coil spring having open ended final windings which are approximately U-shaped, and the connecting elements fully enclosing straight lateral arms (12, 13) of the final windings, wherein the lateral arms of each final winding form a sharp right angle with an intermediate straight central arm (18), the central arm of each final winding overlies the helical circular coils (15, 16) of the associated spring in the manner of a secant, the lateral arms are substantially shorter than the central arms and lie radially outside of the helical circular coils, each lateral and central arm has a single outwardly directed bow-shaped bulge (19), a short length of end wire (14) at an outer lateral arm (12) of each final winding is bent at an approximate right angle to the outer lateral arm and runs parallel to the spring axis (17), all of the coil springs in a row running parallel to the connecting elements are equally aligned, and the coil springs of adjacent flanking rows are rotated 180.degree. relative to the spring axes such that the enclosed lateral arms and central arms of the final windings define zig-zag patterns over upper and lower surfaces of the core to establish uniform surface densities.