PURPOSE: To install each brim shaped reinforcing rib even onto a thin wall duct the both ends of which is formed with flared sections by way of a specified outer circumferential clearance by dividing reach rib by 2 so as to be formed into rib pieces, and thereby holding the duct from both of the upper and lower sides of the duct.
CONSTITUTION: Each brim shaped reinforcing rib 2 is installed onto the outer circumference of a thin wall duct 1 which is 0.3mm in thickness at certain intervals. the both ends of the duct 1 are formed with flared sections 10 so that the ducts 1 can thereby be mutually butt welded. The reinforcing rib 2 is composed of two rib pieces 3 and 4 each of which is in a split half shape, where stepped sections 3a and 4a are formed, which are mutually over-lapped when they are combined with each other. The stepped sections 3a and 4a are mutually over-lapped, and they are spot-welded, so that the rib pieces 3 and 4 are thereby mutually fixed. Following which, the rib 2 is then brazed onto the duct 1.
YONEYAMA KATSUJI
HATANAKA HIROAKI
MURAYAMA TOSHIICHI
