Abstract: A sash system comprises a pair of sash doors including an inner sash door and an outer sash door; an upper sash frame and a lower sash frame; and an inner guide rail built in the upper frame and an outer guide rail built in the lower frame, the door front frame and the door end frame corresponding to each sash door being engaged with the inner guide rail and with the outer guide rail, respectively. Each of the sash doors includes a vertical door front frame, a vertical door end frame, and a pair of horizontal divider panels joined by an intermediate locking frame and connecting the door front frame and the end frame. The intermediate interlocking frame being foldable with respect to a vertical shaft thereof, and is engaged so as to be detachable from each guide rail or from an interlocking frame guide rail in parallel to each guide rail.

Abstract: A sash system is provided that can selectively change the use mode of sash doors by means of a simplified engagement/disengagement mechanism. The sash system comprises a pair of sash doors including an inner sash door and an outer sash door; an upper sash frame and a lower sash frame; and an inner guide rail built in the upper frame and an outer guide rail built in the lower frame, the door front frame and the door end frame corresponding to each sash door being always engaged with the inner guide rail and with the outer guide rail, respectively. Each of the sash doors includes a vertical door front frame disposed on the right end of each sash door, a vertical door end frame disposed on the left end of each sash door, a horizontal divider panel connecting the door front frame and the end frame, and an intermediate interlocking frame disposed to a horizontal intermediate portion of the divider panel, the intermediate interlocking frame being two-folded horizontally with respect to a rotational shaft thereof.