Abstract: A seat has a configuration in which, in each side frame of a cushion frame, an inner frame and an outer frame which have flanges extending along peripheral edges thereof are faced to each other with a space therebetween at least partially, and the flanges are fixed by hemming process along the entire peripheral edges thereof. Since the entire peripheral edges are hemmed, the inner frame and the outer frame are securely fixed. Additionally, since the inner frame and the outer frame which are thin-plate-shaped are used, reduction in weight of each side frame can be achieved. Further, since the inner frame and the outer frame are faced to each other with a space therebetween at least partially, a compressive/tensile strength required as a side frame can be secured by inserting an expanded bead body into the space.

Abstract: A seat has a configuration in which, in each side frame of a cushion frame, an inner frame and an outer frame which have flanges extending along peripheral edges thereof are faced to each other with a space therebetween at least partially, and the flanges are fixed by hemming process along the entire peripheral edges thereof. Since the entire peripheral edges are hemmed, the inner frame and the outer frame are securely fixed. Additionally, since the inner frame and the outer frame which are thin-plate-shaped are used, reduction in weight of each side frame can be achieved. Further, since the inner frame and the outer frame are faced to each other with a space therebetween at least partially, a compressive/tensile strength required as a side frame can be secured by inserting an expanded bead body into the space.

Abstract: A headrest lock structure has a plurality of lock slots formed in a line along the axial direction of a cross-sectionally circular headrest pole and a lock plate is adapted to fit into one of the lock slots. Each lock slot has a bottom surface protruding in an arc within a region concaved from the outer peripheral surface of the headrest pole by a given distance, and a side surface formed on at least one of the sides of the bottom surface in the axial direction of the headrest pole to extend at approximately a right angle with the bottom surface. The lock plate has an arc-shaped concave portion corresponding to the profile of the bottom surface of each lock slot, and a flat portion corresponding to the side surface of each lock slot. The headrest lock structure can reliably prevent unintentional release of headrest lock.

Abstract: A headrest lock structure has a plurality of lock slots formed in a line along the axial direction of a cross-sectionally circular headrest pole and a lock plate is adapted to fit into one of the lock slots. Each lock slot has a bottom surface protruding in an arc within a region concaved from the outer peripheral surface of the headrest pole by a given distance, and a side surface formed on at least one of the sides of the bottom surface in the axial direction of the headrest pole to extend at approximately a right angle with the bottom surface. The lock plate has an arc-shaped concave portion corresponding to the profile of the bottom surface of each lock slot, and a flat portion corresponding to the side surface of each lock slot. The headrest lock structure can reliably prevent unintentional release of headrest lock.