Submerged entry nozzle
A pour tube for casting molten metal is adapted to reduce turbulence and mold disturbances, thereby producing a more stable, uniform outflow. The pour tube has a central longitudinal axis and includes a bore in communication with a port distributor having a greater radius with respect to the longitudinal axis than does the bore. Exit ports provide fluid communication between the port distributor and the exterior of the device. Each of a pair of larger exit ports has a larger cross-sectional area than does either of a pair of smaller exit ports.
1. A pour tube for use in casting a stream of molten metal from an upstream position to a downstream position, the pour tube having a pour tube central longitudinal axis and comprising an inner surface defining a bore and a port distributor in fluid communication, and an outer surface comprising a first pair of larger exit ports having a cross-sectional area and a horizontal width, and comprising a second pair of smaller exit ports having a cross-sectional area and a horizontal width, wherein the larger exit ports and the smaller exit ports are in fluid communication with the port distributor, wherein the port distributor is located downstream of the bore, wherein the port distributor has a greater radius with respect to the longitudinal axis than does the bore, wherein the larger exit ports have a cross-sectional area larger than the cross-sectional area of the smaller exit ports, wherein the exit ports comprise an inner wall and an outer wall, each in communication with the port distributor and the outer surface, and wherein the outer wall has a greater length than the inner wall, and wherein the exit ports have a configuration selected from the group consisting of
(a) being spaced regularly at a rotation angle theta around the periphery of the port distributor, and wherein the exit ports have a port width of at least
2 r pd sin(theta/2) 2
wherein r pd is the port distributor radius and
theta is the rotation angle around the periphery of the port distributor occupied by the port, expressed in radians: and
(b) having a bore radius r b and a number of exit ports n so that
4 πr b >nr pd (theta)>1.37 πr b .
2. The pour tube of claim 1 , wherein each port has a straight central longitudinal axis, and wherein the exit port central longitudinal axes do not intersect the pour tube longitudinal axis.
3. The pour tube of claim 1 , wherein each exit port of the pair of smaller exit ports is disposed in an opposite position, with respect to the other exit port of the pair, on the horizontal circumference of the exterior of the pour tube.
4. The pour tube of claim 1 , further comprising a second pair of larger exit ports.
5. The pour tube of claim 4 , wherein the individual exit ports in each pair of exit ports are disposed in opposite positions around the horizontal circumference of the pour tube.
6. The pour tube of claim 1 , wherein the radius of the port distributor is less than twice the radius of the bore.
7. The pour tube of claim 1 , wherein the exit ports are spaced regularly at a rotation angle theta around the periphery of the port distributor, and wherein the exit ports have a port width of at least
2 r pd sin(theta/2) 2
wherein r pd is the port distributor radius and
theta is the rotation angle around the periphery of the port distributor occupied by the port, expressed in radians.
8. The pour tube of claim 1 , wherein the exit ports are configured so that
4 πr b >nr pd (theta)>1.3 πr b
wherein r b is the bore radius,
n is the number of exit ports,
r pd is the port distributor radius, and
theta is the rotation angle around the periphery of the port distributor occupied by the port, expressed in radians.
9. The pour tube of claim 1 , wherein the exit ports have a nonzero flare angle in the horizontal plane that is equal to or less than theta/2, wherein theta is the rotation angle around the periphery of the port distributor occupied by the port, expressed in radians.
10. The pour tube of claim 1 , wherein the exit ports are configured so that
3 πr b 2 >hna> 0.5 πr b 2
wherein r b is the bore radius,
h is the exit port height,
n is the number of exit ports, and
a is the width of the port entrance.
11. The pour tube of claim 1 , wherein the ratio of the cross-sectional area of a smaller exit port to the cross-sectional area of a larger port is within a range from and including 0.1 to and including 0.9.
12. The pour tube of claim 1 , wherein the ratio of the cross-sectional area of a smaller exit port to the cross-sectional area of a larger port is within a range from and including 0.2 to and including 0.8.
13. The pour tube of claim 1 , wherein the ratio of the cross-sectional area of a smaller exit port to the cross-sectional area of a larger port is within a range from and including 0.3 to and including 0.7.
14. The pour tube of claim 1 , wherein the ratio of the cross-sectional area of a smaller exit port to the cross-sectional area of a larger port is within a range from and including 0.4 to and including 0.6.
15. The pour tube of claim 1 , wherein the ratio of the width of a smaller exit port to the width of a larger port is within a range from and including 0.5 to and including 0.9.
16. The pour tube of claim 1 , wherein the ratio of the width of a smaller exit port to the width of a larger port is within a range from and including 0.6 to and including 0.8.