Tube expansion evaluation and measurement of processing for the “EXPANDER” tube expansion tool

Tube expansion process using the “Tube Expander”

Insertion of tube

Adhesion to the tube and sheet hole

Completion of tube expansion fitting

Tube expansion evaluation and measurement

The appropriate amount of tube expansion for the Tube Expander differs depending on the dimensions of the tube sheet hole diameter, outer diameter of the tube, and tube thickness as well as the material of the tube.
The “tube thickness reduction rate” and “tube inner diameter growth rate” are the two general methods for measuring the degree of tube expansion.

Before tube expansion

After tube expansion

1. Calculation of the tube thickness reduction rate

Wt = ( ( D – d₀ ) – ( H – d₁ ) ) / ( D – d₀ ) × 100
d₁ = H – ( D – d₀) × ( 1 – Wt / 100)

Wt: tube thickness reduction rate (%)
H: sheet hole diameter before tube expansion (mm)
D: outer diameter of tube before tube expansion (mm)
d_0: inner diameter of tube before expansion (mm)
d₁: inner diameter of tube after tube expansion (mm)

2. Calculation of tube inner diameter growth rate

Wd = ( d₁– ( d₀ + C ) ) / ( d₀ + C ) × 100

d₁ = ( d₀ + C ) × ( 1 + Wd / 100 )

In general, it is estimated that Wd is between 1 and 1.2%.

Wd: tube inner diameter growth rate (%)
d₀ : inner diameter of tube before tube expansion (mm)
d₁ : inner diameter of tube after tube expansion (mm)
C: space between sheet hole diameter and outer diameter of tube (mm) ( C = H – D )