Device for spraying a coating on the internal surface of a vessel for transferring molten metal and a method relating to said device

The device for spraying a coating on the internal faces of a vessel (2) for the transfer of molten metal such as a tundish comprises a spraying lance (3) secured to a carriage (4). The carriage (4) is capable of displacement in translational motion on a guide (6; 106) which extends in a first longitudinal or transverse direction (D; L) of the vessel (2) and which is in turn capable of translational motion on guiding means (7; 107) extending in a second direction (L; D) which is transverse with respect to direction (D; L) aforesaid. These guiding means (7; 107) are themselves mounted on a suppport (8, 12) which is capable of translational motion in the longitudinal direction (D).

The present invention relates to a device for spraying a refractory and/or 
heat-insulating and/or water-repellent coating on the internal faces of a 
vessel such as a tundish for transferring molten metal, said coating being 
either permanent or else a wearing coating according to requirements. 
The invention is also directed to a method for the practical application of 
the device in accordance with the invention. 
A coating of this type is described, for example, in French patent No. 
2,585,273 granted to the present Applicant. 
In French patent Applications No. 87 04694 of Apr. 3rd, 1987 and No. 87 
11466 of Aug. 12th, 1987, the present Applicant describes in addition a 
machine for preparing and spraying a similar coating. 
A method of coating which is already known consists in pouring the coating 
composition into the space located between a former and the internal 
surface of the vessel to be coated. 
The use of a former of this type is unpractical and does not make it 
possible to modify the thickness of the coating at will. 
At the present time, in order to spray a coating of this type into a 
transfer vessel, use is made of a robot having articulated arms, the 
movements of which are remote-controlled. 
A robot of this type is of heavy and complex construction, with the result 
that it is very costly. 
There has also been proposed a spraying device comprising a beam fixed 
above a small transfer vessel along the longitudinal axis of this latter, 
a carriage for supporting the lance used for spraying the coating being 
capable of displacement in translational motion on said beam. This device 
is economical but is suitable only for metallurgical vessels of small 
size. Moreover, the device does not make it possible to spray the coating 
at a constant distance between the head of the spraying lance and the 
internal faces of the vessel, with the result that the coating has 
irregular compactness, which is unacceptable. 
This device is unsuitable, especially in the case of transfer vessels which 
have non-parallelepipedal geometrical shapes and the side walls of which 
are not vertical but inclined. 
The object of the present invention is to overcome the disadvantages of 
known designs by producing a spraying device of simple and inexpensive 
construction which makes it possible to obtain a coating of uniform 
compactness irrespective of the dimensions and shape of the transfer 
vessels. 
The device contemplated by the invention for spraying a coating onto the 
internal faces of a vessel for the transfer of molten metal comprises a 
spraying lance secured vertically to a carriage which is displaceable in a 
horizontal plane located above the transfer vessel. 
In accordance with the invention, this device is characterized in that the 
carriage is capable of displacement in translational motion on a guide 
which extends in a first longitudinal or transverse direction of the 
transfer vessel, that said guide is in turn capable of displacement in 
translational motion on guiding means extending in a second direction 
which is transverse with respect to the direction aforesaid, that said 
guiding means are themselves mounted on a support which is capable of 
displacement in translational motion in the longitudinal direction of the 
vessel, and that means are provided for controlling the various movements 
of the spraying lance in such a manner as to maintain the spraying head of 
said lance at a substantially constant distance from the lateral faces or 
from the bottom face of the transfer vessel. 
In view of the fact that the spraying device as a whole can be displaced in 
the longitudinal direction of the transfer vessel, said device can be of 
smaller overall length than the vessel and is thus suitable for vessels 
having both small and large dimensions. 
In view of the fact that the carriage is capable of moving in a direction 
transverse to the length of the vessel, it is possible to adjust the 
distance between the head of the spraying lance and the side wall of the 
vessel, even when this side wall is not vertical but inclined or else not 
parallel to the longitudinal direction of the transfer vessel. 
In an advantageous embodiment of the invention, the spraying lance is 
capable of displacement in rotation and in translational motion on a 
vertical axis. 
These displacements of the spraying lance in combination with the other 
movements of the device in accordance with the invention make it easier to 
maintain a constant distance between the head of the lance and the 
internal surface of the transfer vessel irrespective of the shape of this 
latter. 
In a preferred embodiment of the invention, the support of the device is 
capable of displacement in translational motion on guiding means which 
extend parallel to the longitudinal direction of a plurality of transfer 
vessels disposed in a row. 
The same device of simple, compact and inexpensive construction is thus 
capable of coating in series a plurality of tundishes placed in a row. 
Once the coatings have been completed, it is only necessary to withdraw the 
device to a parking area located beyond the last transfer vessel. 
According to a further aspect of the invention, the method for the 
practical application of the spraying device in accordance with the 
invention involves the following steps : 
a) the support of the device is displaced so as to place it in position 
above the vessel, 
b) the bottom face of the vessel is coated by spraying parallel coating 
strips while displacing the carriage in the longitudinal direction of the 
vessel and in the direction perpendicular to this latter in order to pass 
from one strip to another while at the same time maintaining the head of 
the spraying lance at a constant distance from the bottom face, 
c) at least one longitudinal lateral face and at least one transverse 
lateral face of the vessel are coated by spraying parallel coating strips 
while displacing the carriage in the longitudinal or transverse direction 
of the vessel and displacing the lance head in pivotal motion about its 
axis through an angle of 90.degree. at the end of a longitudinal strip in 
order to spray a strip on the transverse face or conversely and, in order 
to pass from one strip to another, the lance head is displaced vertically 
and the carriage is displaced transversely or longitudinally in order to 
maintain a substantially constant distance between the lance head and the 
lateral face of the vessel, 
d) steps b) and c) may be reversed.

In the embodiment of FIGS. 1 and 2, there is shown a device 1 for spraying 
a refractory and/or heat-insulating and/or water-repellent coating on the 
internal faces of a tundish 2. This coating can be permanent or else can 
be a wearing coating. 
This spraying device comprises a spraying lance 3 secured vertically to a 
carriage 4 which is capable of displacement in a horizontal plane located 
above the tundish 2. The lance 3 is connected to a flexible pipe 5 which 
is in turn connected to a machine for preparation and pressurization of a 
coating composition in the form of a slurry as described, for example, in 
French patent Applications No. 87 04694 of Apr. 3rd, 1987 and No. 87 11466 
of Aug. 12th, 1987 in the name of the present Applicant. 
In accordance with the invention, the carriage 4 is mounted so as to be 
capable of displacement in translational motion on a guide 6 which extends 
in the longitudinal direction D of the tundish 2. Said guide 6 is in turn 
capable of translational displacement on guiding means 7 which extend 
transversely to the aforesaid longitudinal direction D. 
Said guiding means 7 are themselves mounted on a support 8 which is capable 
of displacement in translational motion in the longitudinal direction D of 
the tundish 2. 
Means 9 such as a microcomputer associated with motors are provided for 
controlling the various movements of the spraying lance 3 carried by the 
carriage 4 so as to ensure that the head 3a of said lance is maintained at 
a substantially constant distance from the lateral faces 2a and 2b and 
from the bottom face 2c of the transfer vessel. 
In the embodiment shown, the spraying lance 3 is also capable of moving in 
translation and in rotation along a vertical axis (see arrows F1 and F2 of 
FIG. 2). 
The guide 6 which extends in the longitudinal direction D is a beam on 
which the carriage 4 is movably mounted by means of runner-wheels 4a. 
The opposite ends of the beam 6 have two carriages 6a, 6b equipped with 
runner-wheels and movably mounted on two cross-members 8 which extend at 
right angles to the longitudinal direction D of the tundish 2. 
The opposite ends of the cross-members 8 are provided with runner-wheels 10 
mounted on two guide rails 11 which extend respectively on each side of 
the longitudinal lateral faces 2a of the tundish 2. 
The two cross-members 8 are connected to each other by means of 
longitudinal members 12 which are secured to the ends of said 
cross-members 8 so as to form a rigid frame. 
In the embodiment shown, the length of said frame is substantially equal to 
one-half the length of the tundish 2 whilst its width is slightly greater 
than the width of said tundish. 
Thus, by displacing the carriage 4 on the beam 6 and by displacing the 
carriages 6a, 6b of the beam on the transverse guides 7, the interior of 
the tundish can be coated over one-half of its length and over its entire 
width. 
In the embodiment of FIG. 3, the device 1 is mounted on rails 11 which 
extend parallel to the longitudinal direction D of several tundishes 2, 
2A, 2B, 2C placed in a row. 
Said guide rails 11 extend beyond the end of the tundish 2C located at the 
end of a row so as to constitute a parking area 11a of the device 1 at a 
location which is free from the top opening of each tundish. 
The displacements of the device 1 as a whole on the rails 11, of the 
carriages 6a, 6b of the beam 6, of the carriage 4 on the beam 6, the 
translational motion and rotational motion of the lance 3 carried by the 
carriage 4,are controlled automatically by means of the microcomputer 9 in 
accordance with a predetermined operating cycle which ensures that the 
head 3a of the lance 3 remains at a constant distance from the internal 
surface of the tundishes 2, 2A, 2B, 2C. 
The ends of travel of the device on the rails 11 can be determined by 
electric contactors 13 (see FIG. 1) which stop the operation of the 
driving motor of the device when this latter reaches a position in which 
it is capable of coating one-half of the internal surface of a tundish. 
Thus in the case of each tundish, the device 1 will occupy two successive 
positions, namely the position shown in full lines in FIGS. 1 and 2 and 
the position shown in dashed lines in FIG. 1. 
In the embodiment of FIGS. 6 and 7, the carriage 4 is mounted so as to be 
capable of translational displacement on a guide 106 which extends in the 
transverse direction L of the tundish 2. Said guide 106 is in turn capable 
of translational displacement on guiding means 107 which extend in the 
aforesaid longitudinal direction D. 
The guiding means 107 are themselves mounted on the longitudinal members 12 
which constitute with the cross-members 8, as in the first embodiment 
described in the foregoing with reference to FIGS. 1 and 2, a support 
which is capable of translational motion in the longitudinal direction D 
of the tundish 2. 
The other distinctive features of this second embodiment are identical with 
those of the first embodiment. 
There will now be described by way of nonlimitative limitative example the 
practical operation of the spraying device in accordance with the first 
embodiment of the invention, reference being made to FIGS. 1 to 5. 
In a first stage, the device 1 is displaced on the rails 11 in order to 
place it in position above the tundish 2 as indicated in FIG. 1. In this 
position, the head 3a of the lance 3 is capable of sweeping the entire 
surface of the tundish over one-half of its length. 
The operation is begun by coating the bottom face 2c of the tundish by 
displacing the carriage 4 in a direction F.sub.3 (see FIG. 4) parallel to 
the direction D so as to deposit by spraying a coating strip b.sub.1 which 
extends between the center M of the tundish and the transverse lateral 
face 2b. 
Another coating strip b.sub.2 is then deposited by spraying in juxtaposed 
relation to the first strip after having displaced the carriages 6a and 6b 
at right angles to the longitudinal direction D. The operation is carried 
out in this manner until the entire half-width of the bottom face 2c of 
the tundish has been covered. During this spraying operation, the head 3a 
of the lance remains at a constant distance from the bottom face 2c. 
A longitudinal lateral face 2a and a transverse lateral face 2b are then 
coated by spraying successive parallel and juxtaposed strips such as the 
strip b.sub.3 (as shown in FIG. 5). To this end, the head 3a of the lance 
is brought to the desired distance d from the wall 2a and the carriage 4 
is displaced in the direction F.sub.4 which is parallel to the length D. 
When the head 3a is located at a distance d from the transverse face 2b, 
the head 3a is rotated through an angle of 90.degree. and the carriages 
6a, 6b are displaced in a direction perpendicular to D. 
The following strip is sprayed in the same manner. In view of the fact that 
the lateral walls 2a and 2b are inclined, the distance d between the head 
3a and the internal surface of the tundish is maintained by means of the 
carriages 6a, 6b (in the case of the wall 2a) and by means of the carriage 
4 (in the case of the wall 2b). 
The same procedure is adopted for the other half-width and the other 
half-length of the tundish. 
The operation of the spraying device in accordance with the second 
embodiment of the invention is wholly comparable with the procedure 
described in the foregoing. Thus the carriage 4 moves along the beam 106 
along the transverse direction L with respect to the tundish 2 whilst the 
beam 106 in turn moves along the longitudinal guides 107. 
As can be understood, it is also possible to reverse the steps described in 
the foregoing and to perform the coating operation first on the transverse 
and longitudinal lateral faces (in any order and direction) and then on 
the bottom face of the tundish. 
The principal advantages of the spraying device which has just been 
described are as follows : 
The device is of simple, lightweight and compact construction and does not 
interfere with the access to the different tundishes. 
Its different elements are displaced in simple movements of translation and 
rotation which can readily be programmed. 
These various movements serve to maintain the head 3a of the lance at a 
constant distance from the internal surface of the tundish at any point of 
this latter, thus making it possible to obtain a coating which has a 
uniform degree of compactness. 
Moreover, in spite of its small dimensions, the device is capable of 
coating the interior of several tundishes in a row. 
It should be clearly understood that the invention is not limited to the 
examples of construction which have just been described and that any 
number of modifications can be made in these latter without thereby 
departing from the scope of the invention. 
Thus the structure of the device can be modified on condition that the 
different fundamental movements of the carriage 4 are retained. 
Similarly, the microcomputer 9 can be replaced by remote controls actuated 
manually by an operator or installed in parallel with such controls. The 
length of the longitudinal members 12 can be different from the length 
indicated above and steps can be taken to ensure that the lance 3 is 
capable of rotating about its own axis through a number of successive 
quarter-revolutions. 
Furthermore, detection means can be associated with the programmed 
microcomputer or with the manually actuated remote controls for 
controlling the movements of the carriage 4 and of the lance 3. Said 
detection means make it possible to maintain a constant distance between 
the surface to be coated and the head 3a of the spraying lance and may 
consist, for example : 
of sensitive telescopic rods for detecting a constant distance and 
producing action on switches which are capable of controlling the 
different motors for ensuring the powered mobility of the device, 
ultrasonic probes, 
infrared-radiation probes. 
On the other hand, the practical application of the device and of the 
coating can be different from those described. Thus, if the width of the 
tundish 2 and the conditions of spray deposition of said coating are 
appropriate, it can be possible, in particular with the device in 
accordance with the first embodiment, the device being placed at one end 
of the tundish, to coat the transverse face 2b and the beginning of the 
two longitudinal faces 2a without displacing either the carriage 4 or the 
beam 6, simply by pivoting the spraying lance 3 and if necessary by 
adjusting its level in height, and to terminate the coating by displacing 
the carriage 4 lengthwise along the beam 6 and by displacing this latter 
along the rails 11.