US2012106588A1PendingUtilityA1
Pool power-based apparatus to control vacuum arc remelting processes
Est. expiryAug 8, 2026(~0.1 yrs left)· nominal 20-yr term from priority
Y02P10/25H05B 7/144F27D 11/08F27D 19/00F27D 21/00F27B 3/085
53
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Claims
Abstract
An apparatus for controlling a vacuum remelting furnace comprising a controller capable of adjusting electrical current to an electrode and a controller capable of adjusting the electrode's drive speed. The controllers adjust the current and drive speed based on a predetermined pool power reference value. The apparatus may also comprise a third controller that receives the adjusted current and drive speed as inputs and sends estimated electrode drive speed bias as output to the drive speed controller and estimated current bias as output to the current controller.
Claims
exact text as granted — not AI-modified1 . An apparatus for controlling a remelting furnace, said apparatus comprising:
a. an electrode located in a remelting furnace; b. an electrical current supply capable of supplying current to the electrode; c. a first controller capable of adjusting the current supplied to the electrode based upon a predetermined pool power reference value; and d. a second controller capable of adjusting electrode drive speed based upon a predetermined pool power reference value.
2 . The apparatus of claim 1 additionally comprising a third controller capable of receiving adjusted current and adjusted electrode drive speed as inputs.
3 . The apparatus of claim 1 additionally comprising a non-linear third controller capable of receiving adjusted current and adjusted electrode drive speed as inputs.
4 . The apparatus of claim 1 additionally comprising a third controller capable of receiving adjusted current and adjusted electrode drive speed as inputs, wherein the first and second controllers are capable of adjusting current and drive speed based upon output from the third controller.
5 . The apparatus of claim 4 wherein the third controller outputs an estimated current bias to adjust current supplied to the electrode.
6 . The apparatus of claim 4 wherein the third controller outputs an estimated electrode drive speed bias to adjust the electrode drive speed.
7 . The apparatus of claim 2 wherein said third controller employs the following equation in its operation:
I
=
-
V
CF
2
(
R
I
+
R
G
G
)
+
(
V
CF
2
(
R
I
+
R
G
G
)
)
2
+
P
pool
+
α
r
C
S
Δ
A
e
h
sup
Δ
(
μ
C
Sp
h
sup
h
m
+
ɛ
)
(
R
I
+
R
G
G
)
,
wherein P pool is a pool power reference setpoint, sup is a volume specific enthalpy at superheat temperature, c is an arc power fraction to the pool surface, V CF is a cathode fall voltage, R I is a VAR circuit resistance less an electrode gap resistance, R G is an experimentally determined electrode gap resistance parameter, G is an electrode gap, A e is an electrode cross-sectional area, α rr is a room temperature thermal diffusivity, C SΔ and C Sp are material dependent constants, μ is a process efficiency, Δ is an electrode thermal boundary layer, and h m , is a volume specific enthalpy at melt temperature.
8 . The apparatus of claim 1 wherein said first controller employs the following equation in its operation:
f
I
=
-
(
V
CF
+
〈
V
^
b
〉
)
2
(
R
I
+
R
G
〈
G
^
〉
)
+
(
(
V
CF
+
〈
V
^
b
〉
)
2
(
R
I
+
R
G
〈
G
^
〉
)
)
2
+
〈
P
pool
,
ref
〉
+
α
r
C
S
Δ
A
e
h
sup
〈
Δ
^
〉
(
〈
μ
^
〉
C
Sp
h
sup
h
m
+
ɛ
)
(
R
I
+
R
G
〈
G
^
〉
)
,
wherein P pool is a pool power reference setpoint, h sup is a volume specific enthalpy at superheat temperature, c is an arc power fraction to the pool surface, V CF is a cathode fall voltage, R I is a VAR circuit resistance less an electrode gap resistance, R G is an experimentally determined electrode gap resistance parameter, G is an electrode gap, A e is an electrode cross-sectional area, α rr is a room temperature thermal diffusivity, C SΔ and C Sp are material dependent constants, μ is a process efficiency, Δ is an electrode thermal boundary layer, and h m is a volume specific enthalpy at melt temperature, V b is a voltage bias, a circumflex over a variable indicates that it is an estimated value supplied by a nonlinear remelting estimator, and the angular brackets indicate variables supplied to the equation as opposed to constants.
9 . The apparatus of claim 1 wherein said second controller employs the following equation in its operation:
f
G
=
〈
α
^
〉
h
sup
A
e
{
〈
P
pool
,
ref
〉
-
ɛ
[
(
V
CF
+
〈
V
^
b
〉
)
〈
I
c
〉
+
(
R
I
+
R
G
〈
G
^
〉
)
〈
I
c
〉
2
]
}
,
wherein P pool is a pool power reference setpoint, h sup is a volume specific enthalpy at superheat temperature, c is an arc power fraction to the pool surface, V CF is a cathode fall voltage, R I is a VAR circuit resistance less an electrode gap resistance, R G is an experimentally determined electrode gap resistance parameter, G is an electrode gap, A e is an electrode cross-sectional area, I c is a commanded current, a circumflex over a variable indicates that it is an estimated value supplied by a nonlinear remelting estimator, and angular brackets indicate variables supplied to the equation as opposed to constants.
10 . The apparatus of claim 1 . wherein the second controller adjusts drive speed based upon a predetermined gap distance of the electrode from a surface of a pool of molten metal or a predetermined depth of the electrode in slag.Cited by (0)
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