This entry presents the idea of design and manufacturing of an automatic corrugating machine. This machine is used for automatic develop and creation of helical formed slits on heat transfer tubes. In other way, the presenting machine transform a simple tube into corrugated ones by the use of plastic roll forming strategy.
This machine has two strategic stations, the rotary holding station and forming station. At rotary station, the tube is simultaneously holed and fed forward using two radial rollers with adjustable center distance for working on different diameter tubes. At forming station, the corrugations are created using a tiny forming roller made with high strength and hard carbon steel. The forming roller can move downward using a rectangular threaded screw installed at the top side of forming station. The angle of roller is also adjustable for different pitched helical corrugations. At forming station, because of huge amount of forces created by forming roller, the tube is supported by another roller in opposite side of forming roller or at the beneath of forming station. This support prevents tube bending during forming process. To prevent any kinds of erosion between tube and roller, this support is installed in a specific angle. By fastening the screw at the top side of forming station, the forming roller forms the tube and because of its angle, it pulls the tube from rotary holder into its station. By moving forwards and also rotation of tube, a helical corrugation is created on a simple tube. For high deep sluts, it is recommended to do the process in more than one step to prevent any kind of damages into different parts of forming station.
The rotary holder is rotated using a 3 phase electric motor connected to a gearbox. An inventor controls the rotation speed of electric motor and rotary holder. For deep corrugated tubes, after on pass of forming, the angle of motor is reversed by a two mechanical micro-switches which are installed at left and right side of machine. The distance of these micro-switches determines the length of corrugation through the length of tube.
The corrugated tubes transfer the laminar heating flow into turbulent in fired tube boilers and have a huge effects in efficiency of boilers and heat exchangers. An automatic fast way to create these kinds of tube is highly demanded by heat equipment manufactures. As an example, a single tube with 6 m in total length and 2” diameter with 3 cm corrugation pitch is corrugated within only 2 minutes with no surface damages on the tube. This machine with size of 1000 mm in length and 600 mm in width could be selected as a portable machine for installing in different location of production halls. This machine has a prototype and a picture of a corrugated tube made by this machine is attached in illustrations.