Information
-
Patent Grant
-
6506337
-
Patent Number
6,506,337
-
Date Filed
Friday, April 6, 200123 years ago
-
Date Issued
Tuesday, January 14, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 266 143
- 266 144
- 266 287
- 266 276
-
International Classifications
-
Abstract
An arrangement of operating stations and equipment for the rapid preparation and transport of molten metal ladles and pouring tanks with covers to a pouring station of a pressure-pouring operation, and a method of providing the moving, placement and transport of the ladles and pouring tanks for the minimization of the loss of time between end of the first stage of pouring and initiation of the second stage of pouring.
Description
BACKGROUND OF THE INVENTION
The present invention is directed to method and apparatus for moving molten metal ladles between a cover position, a ladle-load position and a pouring position at a casting station. More particularly, a method and an apparatus are taught which enhance a pressure casting process to expedite the movement from the pouring station of a molten-metal evacuated ladle and the positioning of a molten-metal filled ladle at the pouring station without the intermediate delays associated with ladle covering and uncovering.
Casting and casting practices generally involve the use of molten metals at elevated temperatures. This molten metal practice requires the use of heavy apparatus for the holding and transport of the metal. Specifically, molten metal for casting is frequently held in large steel or cast-iron ladles lined with refractory brick. In a pressure-casting or pouring operation, the ladle is placed in a pouring tank and a tank cover is placed atop the pouring tank. This tank cover is equipped with a pouring tube as well as ports to elevate the gas pressure above the molten metal. Avoidance of fracture of the pouring tube and refractory linings generally involves maintaining or preheating the pouring tank cover and pouring tube. A holding or heating furnace is frequently utilized for this purpose. However, the physical act of positioning the pouring tank cover atop the pouring tank and thereafter securing the pouring tank cover are time-consuming operations and an inhibition to a rapid production operation.
A presently known operation utilizes a single pouring or casting station in cooperation with twin ladle-loading stations. These ladle-loading stations use pressure-pouring tanks on transfer cars for holding the hot-metal ladles, and for transporting the ladles between the ladle-loading stations and the pouring station. In this operation, a ladle of molten metal is transported to a pressure-pouring tank at a ladle-loading station for subsequent transfer of the ladle containing pouring tank to the pouring station. At the pouring station, a pressure-pouring tank cover is positioned on and secured to the pressure pouring tank by the pouring crane. After pouring of the molten metal from the ladle, the pressure pouring tank cover is removed using the pouring crane. The pressure pouring tank is then transported to the first ladle-loading station for eventual filling with another ladle of molten metal. A second molten-metal-filled ladle in a pressure pouring tank is then transported to the pouring station from the second ladle-loading station and a pressure pouring tank cover is positioned and secured to the second pressure pouring tank at the pouring station, as described above.
The time delays in pressure pouring tank covering and the use of the pouring crane at the pouring station are significant when measured in terms of daily lost production of large castings. Accordingly, it is an object of the present invention to provide a more efficient pressure pouring arrangement.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus to provide a more efficient arrangement for bottom-pressure casting. In this method, the pressure pouring tank cover is secured on a first pressure pouring tank at a ladle-load station prior to moving the covered pressure pouring tank with a full ladle into the pouring-station position. Further, subsequently but prior to the emptying of the first ladle, a second metal-filled ladle in a second pressure pouring tank is positioned in a second ladle-load station with its pressure pouring tank cover secured. The second covered pressure pouring tank is ready for immediate movement into the pouring station after emptying of the first ladle and the removal of the first pouring tank from the pouring station without removal of the first pressure pouring tank cover. The pressure pouring tank covers are moved onto the pouring tanks at the ladle-load stations by a jib crane or overhead crane. The pressure pouring tank covers with their pouring tubes are maintained at an elevated temperature at cover station ovens within the range of motion of the jib crane or overhead crane. The second pressure pouring tank is available for immediate placement into the pouring station to continue production as soon as the first pressure pouring tank with its empty ladle has been moved a distance adequate to provide the necessary clearance for the second pressure pouring tank transfer-car bearing a second metal-filled ladle.
BRIEF DESCRIPTION OF THE DRAWING
In the drawings,
FIG. 1
is a schematic outline of the locations of the pressure pouring tank positions of the prior art practice, and
FIG. 2
is a schematic plan view of the locations of the several positions for the pressure pouring tanks of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Known bottom-pressure casting practice in the industry utilizes a two-ladle-load-station practice to transfer molten-metal filled ladles to a single pouring station, which practice was considered an improvement over the older practice of a single pouring station and a single ladle-load station. It is recognized that molten metal is provided from steel manufacturing furnaces, such as basic oxygen furnaces or electric arc furnaces, which furnaces and furnace practice are known but not shown.
This casting process is directed to the bottom-pressure pouring and casting of railroad wheels. The railroad wheels are steel castings weighing upwards of six hundred pounds and produced from molten steel poured at about 2900° F.
Referring now to
FIG. 1
, a prior art bottom pressure casting pouring station with two ladle-loading stations is shown.
The single pouring station is shown at
112
, with track
122
leading to ladle-loading station
114
and track
124
leading to ladle-loading station
116
. Pouring crane
127
is seen to move laterally along bridge
118
which itself moves transversely along support rails
126
,
128
.
In a known pouring operation utilizing the prior art arrangement of
FIG. 1
, ladle
134
of molten metal is placed in pouring tank
135
in tank transfer car
136
at ladle-loading station
114
. Tank transfer car
136
is rolled across track
122
into pouring station
112
.
Pouring tank cover
129
is then placed on pouring tank
135
utilizing pouring crane
127
. Pouring tank cover
129
is kept in a holding oven located transversely from pouring station
112
within support rails
126
,
128
.
When ladle
134
is empty, pouring crane
127
is utilized to remove pouring tank cover
129
. Pouring tank transfer car
136
is then rolled out of pouring station
112
back to ladle-loading station
114
.
Another pouring tank transfer car
146
with pouring tank
145
on it and with fill ladle
144
within pouring tank
145
has been prepared at ladle-loading station
116
. Tank transfer car
146
is rolled across track
124
into pouring station
112
. Another pouring tank cover identical to cover
129
is then placed on pouring tank
145
utilizing pouring crane
127
. Pouring tank cover
129
is left in a holding oven located transversely from pouring station
112
within support rails
126
,
128
.
Positioning pouring tank cover
129
over pouring tank
135
at pouring station
112
generates a delay in initiating actual casting of railroad wheels. It is estimated that this delay can be between eight and 10 minutes. In a casting practice manufacturing one casting per minute, this is considered a significant time loss when placed in the context of approximately forty-five ladles of molten steel being poured per day.
In
FIG. 2
, an arrangement in accordance with the present invention is shown. Pouring station
12
is operatively connected to ladle-load-stations
14
and
16
by tracks
60
and
62
. Jib crane
28
with center pivot
30
is located between, and offset from, ladle-loading stations
14
and
16
. In this configuration, jib crane
28
may be rotated about center
30
and extends over ladle-loading stations
14
and
16
. Alternatively, overhead crane
70
along tracks
72
,
74
can be utilized to transfer ladles from ladle-loading stations
14
,
16
to pouring station
12
and pouring tank covers to and from cover holding ovens
50
,
52
to ladle-loading stations
14
,
16
.
First pouring tank cover holding oven
50
and second pouring tank cover holding oven
52
are displaced from pouring station
12
, as well as ladle-load stations
14
and
16
. Pouring tank cover holding ovens
50
and
52
, and ladle-load stations
14
and
16
are symmetrically arranged, but this is merely illustrative and not a limitation. Pouring tank cover
20
and its pouring tube are preheated to avoid thermal shock at introduction of the pouring tube into a molten metal in ladle
21
. Jib crane
28
or overhead crane
70
is operable to grasp pouring tank cover
20
from either of pouring tank cover ovens
50
and
52
, and to move pouring tank cover
20
over either pouring tank
23
or
29
at ladle-load station
14
or
16
.
In an illustrative operation, a pressure-pouring tank transfer car
33
with a molten-metal filled ladle
21
in pouring tank
23
is positioned at ladle-load station
14
in preparation for transfer to pouring station
12
. Pouring tank
23
with ladle
21
therein will have pouring tank cover
20
positioned and secured thereon with a pouring tube extending into molten metal bath in ladle
21
by the use of jib crane
28
or overhead crane
70
. Thereafter, pouring tank
23
is transferred to pouring station
12
on transfer car
33
over rails
60
for continuation of the casting operation.
After casting the metal in ladle
21
at pouring station
12
, evacuated ladle
21
and transfer tank car
33
are returned to ladle-load station
14
for removal of pouring tank cover
20
. Simultaneously, a full ladle
27
in pouring tank
29
covered with pouring tank cover
39
, having been installed by jib crane
30
or overhead crane
70
, has been readied at second ladle-load station
16
. Covered pouring tank
29
at second ladle-load station
16
is then moved into position at pouring station
12
along tracks
62
on second transfer car
31
as soon as first transfer car
33
has moved a distance from station
12
adequate to provide clearance to pouring station
12
for second tank transfer car
31
.
It can be appreciated that the covering and uncovering of pouring tank
22
is now conducted at ladle-load stations
14
and
16
instead of pouring station
12
, which greatly lessens the interruption of pouring operations at pouring station
12
. For example, the total turnaround time for transfer of a ladle
134
with the transfer system of the prior art required eight to ten minutes with the above-described ladle handling procedure at pouring station
112
. With the present invention and use of ladle-load stations
14
and
16
and holding ovens
50
,
52
, the calculated time for removal of pouring tank
23
with ladle
21
from pouring station
12
and the placement of covered pouring tank
29
from ladle-load station
16
to pouring station
12
is three minutes, a saving of at least five minutes.
Claims
- 1. A method of pouring molten metal from a ladle, said method comprising:placing a first ladle of molten metal in a first pouring tank and placing a first cover from a holding oven on said first pouring tank at a first ladle loading station, transferring said first pouring tank with said first ladle and said second pouring truck cover to a pouring station, pouring said molten metal from said first ladle, and before said first ladle is emptied of said molten metal, placing a second ladle of molten metal in a second pouring tank and placing a second cover from said holding oven on said second pouring tank at a second ladle loading station, when said first ladle is empty of molten metal, transferring said first pouring tank from said pouring station, and then transferring said second pouring tank with said second ladle of molten metal and said second pouring tank cover to said pouring station, further comprising the steps of utilizing a first transfer car to transfer said first pouring tank to said pouring station, and utilizing a second transfer car to transfer said second pouring tank to said pouring station.
- 2. The method of claim 1wherein said first pouring tank cover is placed on said first pouring tank at a first ladle-loading station by the use of a crane, and said second pouring tank cover is placed on said second pouring tank at a second ladle-loading station by the use of said crane.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4199350 |
Kutscher et al. |
Apr 1980 |
A |
4825772 |
Jeffreys |
May 1989 |
A |
5480127 |
Choudhury et al. |
Jan 1996 |
A |