SHAPE RETAINING DEVICE FOR AIR DUCT

摘要

PROBLEM TO BE SOLVED: To provide an air duct having a simple structure and capable of being easily assembled. SOLUTION: In the air dust having wall members for forming the duct and a shape retaining strut for connecting two facing surfaces of the wall members, external threads to be inserted through the wall members are formed on the ends of the shape retaining strut, and the wall members are pinched between positioning nuts screwed to the external threads and bottomed nuts. The external thread provided on the end of the shape retaining strut is formed by a rolling method, and the screwing limit of the positioning nut is regulated by the boundary between the external thread formed end and the central part formed inside it and having no screw thread.