2.5 Effect of Welding Speed on Keyhole Profile
45
Table 2.2 Comparison of the keyhole geometry parameters at different welding speeds
Welding speed (m/s)
β(º)
ϕ t (mm)
ϕ b (mm)
(mm)
P γ N/m 2
0.025
61.9
1.22
0.39
0.056
200
0.04
58.1
1.06
0.28
0.333
230
0.05
52.0
1.01
0.20
0.366
270
0.06
43.4
0.966
0.11
0.398
310
P γ = κγ
(2.53)
where: P γ —surface tension pressure;
k —keyhole wall curvature;
γ —surface tension coefficient of keyholes;
− → n —normal direction of the keyhole surface.
Obviously, Fig. 2.14 simplifies the complex variation of the keyhole geometry
with three parameters R 1 , R 2 , and, R 3 . Formula (2.7) can be rewritten as follows:
κ = γ
1
R 1
+
1
R 2
+
1
R 3
(2.54)
Table 2.2 shows the calculation results of the keyhole diameter and the center
position offset of the upper and lower outlets at different welding speeds when the
laser power is 3000 W. In addition, the.
keyhole inclination angle β and the keyhole surface tension pressure P γ corresponding to the welding speeds are also given. Figure 2.15 shows the variation of
keyhole parameters with the increase of welding speed during deep penetration laser
welding. It can be seen that the diameter of keyhole outlet decreases with the increase
of welding speed, and the change of upper keyhole outlet is greater than that of lower
keyhole outlet. In other words, at constant laser power, the diameter of the lower and
upper keyhole outlets changes by 71.8% and 20.8%, respectively. The lower keyhole
outlet is more sensitive to the change of welding speed. In Fig. 3.15, it can be seen
that with the increase of welding speed, the offset of the center position of the upper
and lower outlets of the keyhole increases continuously, but between 0.025 m/s and
0.04 m/s, the variation of the offset is greater. The increase of the offset of the center
position of the upper and lower outlets of the keyhole means that the probability
of interaction between laser beam and material is increased. In this way, the material welded can receive more laser energy when the welding speed is higher, so as
to compensate for the decrease of the interaction time between laser beam and the
material welded due to the acceleration of welding speed.
Figure 2.16 shows that the inclination angle of the front wall and the surface
tension pressure of the keyhole vary with the increase of welding speed when the laser
power is 3000 W. Obviously, the inclination of the front wall of the keyhole decreases
with the increase of welding speed, while the change pattern of the surface tension
45
Table 2.2 Comparison of the keyhole geometry parameters at different welding speeds
Welding speed (m/s)
β(º)
ϕ t (mm)
ϕ b (mm)
(mm)
P γ N/m 2
0.025
61.9
1.22
0.39
0.056
200
0.04
58.1
1.06
0.28
0.333
230
0.05
52.0
1.01
0.20
0.366
270
0.06
43.4
0.966
0.11
0.398
310
P γ = κγ
(2.53)
where: P γ —surface tension pressure;
k —keyhole wall curvature;
γ —surface tension coefficient of keyholes;
− → n —normal direction of the keyhole surface.
Obviously, Fig. 2.14 simplifies the complex variation of the keyhole geometry
with three parameters R 1 , R 2 , and, R 3 . Formula (2.7) can be rewritten as follows:
κ = γ
1
R 1
+
1
R 2
+
1
R 3
(2.54)
Table 2.2 shows the calculation results of the keyhole diameter and the center
position offset of the upper and lower outlets at different welding speeds when the
laser power is 3000 W. In addition, the.
keyhole inclination angle β and the keyhole surface tension pressure P γ corresponding to the welding speeds are also given. Figure 2.15 shows the variation of
keyhole parameters with the increase of welding speed during deep penetration laser
welding. It can be seen that the diameter of keyhole outlet decreases with the increase
of welding speed, and the change of upper keyhole outlet is greater than that of lower
keyhole outlet. In other words, at constant laser power, the diameter of the lower and
upper keyhole outlets changes by 71.8% and 20.8%, respectively. The lower keyhole
outlet is more sensitive to the change of welding speed. In Fig. 3.15, it can be seen
that with the increase of welding speed, the offset of the center position of the upper
and lower outlets of the keyhole increases continuously, but between 0.025 m/s and
0.04 m/s, the variation of the offset is greater. The increase of the offset of the center
position of the upper and lower outlets of the keyhole means that the probability
of interaction between laser beam and material is increased. In this way, the material welded can receive more laser energy when the welding speed is higher, so as
to compensate for the decrease of the interaction time between laser beam and the
material welded due to the acceleration of welding speed.
Figure 2.16 shows that the inclination angle of the front wall and the surface
tension pressure of the keyhole vary with the increase of welding speed when the laser
power is 3000 W. Obviously, the inclination of the front wall of the keyhole decreases
with the increase of welding speed, while the change pattern of the surface tension