| 摘要 |
PURPOSE:To increase hardness of a spring without causing the large weight and the like, in the spring used for a mattress and the like, by forming the section of a spring steel wire to an oval shape and positioning the longitudinal direction of said oval shaped section in the flectional direction of the spring. CONSTITUTION:Each spring 2a, 2b of a spring structural unit 1 continuously forms plural spiral parts 3a, 3b, parallelly provided with their axial line, and almost Z-shaped connecting levers 4a, 4b, respectively connecting upper and lower ends of each neighboring spiral part 3a, 3b, by curving a hard steel wire of oval shaped section. A longitudinal direction of the oval shaped section of the hard steel wire is positioned in almost the axial line direction in each spiral part 3a, 3b, while positioned in the axial line direction of the spiral parts 3a, 3b in the connecting levers 4a, 4b. |
