TUBE EXPANDERS
Main Parts of Tube Expander
Roller
The roller applies a rolling pressure to facilitate deformation of the inside of the tube. It has a tapered shape and is designed so that the insides of expanded tubes always acquire a spherical shape. In addition, the tip of the roller has a smooth R-shape bevel. This helps avoid intensive stress after tube expansion as well as prevent sharp edges from forming on the inside of the tubes.
Mandrel
The mandrel is used to rotate the roller through contact friction. It has a tapered shape just like the roller. The roller and mandrel are both required to be pressure and abrasion resistant.
Cage
The Cage keeps the position of the rollers at regular intervals and prevents falling. It also provides a feed angle to the groove at which the roller is inserted. Therefore, a configuration is achieved in which the mandrel is rotated clockwise. This, in turn, creates a screw-feed like self-propulsion mechanism that results in automatic tube expansion.
Collar
Attaching a bearing collar has the result of lowering thrust at the time of tube expansion as well as preventing damage to the tube end and tube sheet. In addition, by adjusting the installation position forward or backward, it is possible to achieve an effective length and reach length for the roller.
Tube expanders are the tools that are used to increase the outer diameter of the tubes in Boilers, Heat Exchangers, Chillers, Coolers and various Shell and Tube type devices.
The Tube Expander is made up of several individual sections of steel placed around a threaded shaft with wedge shaped nuts on each end of it. The entire assembly is held together by a spring that encircles each end. After which, the assembly is slid into the end of a piece of tubing. The Tube Expander is then tightened, drawing the wedge nuts inside of the steel sections. The wedges are now drawn into the sections at the same time they are forced outward resulting in the expansion of the tubing. Tube Expanders typically come in various standard / customised sizes.
It is sometimes necessary to heat the tube to aid in the expansion process. By applying direct heat to the tube, it would become more pliable and the Expander would not need to work as hard with so much force in order to expand the tube. This process is known as 'Hot Expansion'. The application of using heat while the Expander is inside of the pipe can cause the Expander to seize and break. Additionally, it is also a good idea to spray the inside of the tube with lubricant. The usual oil to use is the all-purpose oil to provide aid for the Tube Expander in sliding inside the tube as it opens.
It is critically essential while selecting most suitable and appropriate Tube Expander, which ensures better joints, good finishing and less wear and tear of the Tube Expander.