What type of processing does the “EXPANDER” tube expansion tool perform?

The Tube Expander consists of four main parts.

The roller applies a rolling pressure to facilitate plastic 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 chamfer. This helps avoid intensive stress after tube expansion as well as prevent sharp edges from forming on the inside of the tubes.

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. Therefore, they utilize a special steel and undergo proper heat treatment as well as finishing by means of precision grinding.

The frame 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.

A bearing collar is attached to the Tube Expander. (Except BK-type)
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 expansion can be roughly divided into two categories: “parallel tube expansion” and “flare tube expansion”.