A tube expander is a tool mainly designed for increasing the internal diameter of the tubes by reducing the tube wall. The outer diameter of the tube is compressed against a fixed container to increase the size of the tube. In simple words, tube expanders are a kind of expansion tool used to enlarge the diameter of the tubes.
During the manufacturing process of heat exchangers, the rolling tube types expansion tools are immensely used. These tools are commonly known as “Tube Expanders.” Condensers and boilers are a type of heat exchanger which requires tubes of different sizes in their components. The tubes’ size is increased with a tube expander’s help.
Components of a tube expander
In general, a Tube Expander Tool consists of four main components: Roller, Mandrel, Frame, and Bearing Collar. The components of a tube expander are described below-
- Roller: It is the foremost part of the tube expander. It has a tapering shape on the front. The first part of the tube expander goes inside the pipe. It ensures the spherical shape of the pipe during the expansion process. It is specially designed to apply the rolling pressure in the internal walls of the tube. The primary function of the roller is to facilitate the deformation of the material (i.e., plastic or metal) inside the tube.
- Mandrel: It is present behind the roller. Like the roller, it has a tapering shape too. It plays a central role in rotating the roller. It accomplishes the purpose of rotating the roller by contact friction. Fiction plays a central role in increasing the diameter of the targeted pipe (Note: Targeted pipe is the pipe whose diameter is increased with the help of the tube expander tool). The mandrel is made up of unique steel material. They undergo a considerable heat treatment too. This is because the mandrel needs to have a good resistance against pressure and abrasion to confer a good amount of friction during the reshaping of pipes.
- Frame: The frame is the backbone of the tube expander tool. It is responsible for maintaining the fixed position of the roller at specific and frequent intervals. It also helps to avoid any failure of the tool at the time of working on increasing the pipe’s diameter. It provides a feed angle to the hole or the furrow of the pipe where the roller is inserted. It helps to attain a configuration of the tool in which the mandrel and the roller are rotated vigorously through friction in a clockwise direction.
- Bearing Collar: It is attached separately to the tube expander. It lowers the thrust and damage during the time of the tube expansion. It smoothens the expansion process due to less likelihood of tube and tube sheet damage. It also helps to gain an adequate length for the roller by aiding the adjustment of the installation position of the tool in the forward or backward direction.
Types of Tube Expansion processes
The tube expansion processes are categorized into two types, namely-
- Parallel Tube Expansion– This process is used to expand the tubes of heat exchangers like steam condensers or boilers. It includes MB-type and CB-type expanding tools.
- Flare Tube Expansion– This process aids in the expansion process by providing a flare shape to the endpoints or the starting points of the tubes. It works like a tensile stress reinforcement. They are commonly used for expanding the boiler tubes.
Final Words
A tube expander tool is efficient for changing or increasing the diameter of the pipes. They come in different sizes. They have a wide application in heat exchangers’ plumbing and manufacturing processes.
