Top of the page To the text skip menu
HOME > What type of processing does the "Expander" tube expansion tool perform?
Display print image

What type of processing does the "Expander" tube expansion tool perform?

"Expander" processing

aquasetter-workimageTube Expanders are rolling tube type expansion tools used for fixing and molding tubes to tube sheets in the manufacturing processes of heat exchangers such as boilers and condensers.

Construction of a Tube Expander

The Tube Expander consists of four main parts.

Example of CB construction

type-CB-Construction-drawing

Example of BK construction

type-BK-Construction-drawing

1. Roller

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.

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

3. Frame

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.

4. Bearing collar

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.

Types of tube expansion

Tube expansion can be roughly divided into two categories: "parallel tube expansion" and "flare tube expansion".

Parallel tube expansion

Parallel tube expansion is mainly used in the expansion of tubes of heat exchangers, steam condensers, boilers, etc.
Tube Expanders applicable to this type of work use the MB-type, CB-type, and HB-type.

Parallel-EXP

Flare tube expansion

Flare tube expansion expands tubes by providing a flare shape to the end of the tubes, while also acting as a reinforcement to tensile stress.
This type of tube expansion is mostly used for boiler tubes.
Tube Expanders applicable to this type of work use the BK-type (including the BKC-type).

Flare-EXP

Tube expansion evaluation and measurement related to the "Expander" tube expansion process

  Click here for the tube expansion evaluation and measurement related to the "Expander" tube expansion process (tube expansion ratio and thickness reduction rate).