To provide a seat for chairs which keeps an inner shell tightened to a seat outer shell by a screw and a nut with one-touch operability for the incorporation of the nut.
The nut 18, which has an overhanging part 18a and is elliptical, has a cylinder section 18b. The tightening part 16 of the inner shell 8 has a nut receiving part 20 in which a screw passing through hole 21 is provided, a rotation stopping stopper 23 which non-rotatably holds the nut 18 in a screw direction, a coming-off stopping stopper 24 which inseparatably holds the nut 18 from the inner shell 8, and an auxiliary stopper 26 which blocks the nut 18 from return revolution. The nut 18 is held in a non-rotatable and non-comming-off state by one-touch operation of pushing and rotating while overlapping on the free zone of the nut receiving part 20.
Tadashi Higashino
Hiroyuki Nishi
Ryuichi Watanabe