... .After spiral duct,the ovalizer duct machine expands it into standard size,with the character of good shape,high efficiency,easy operation ... has less requirement of area.It can be processed duct with width of 3.0m,thickness of 1.2mm. 3,In ... .After spiral duct,the ovalizer duct machine expands it into standard size,with the character of good shape,high efficiency,easy operation ...