Stepped gate safety arrangement

Apparatus for loading a gate into a valve mechanism with a gate safety arrangement for physically preventing the gate from being loaded into the valve mechanism unless the gate has a prescribed orientation with respect to the loading path into the valve mechanism.

BACKGROUND OF THE INVENTION 
This invention relates generally to slide gate valve mechanisms for 
controlling the flow of molten metal and more particularly to a gate 
safety arrangement which permits loading a gate into such a valve 
mechanism only when the gate has a predetermined orientation. 
Valve mechanisms for controlling the flow of molten metal from a holding 
vessel are commonly available. One type of such valve mechanism uses slide 
gates which are first moved into a loaded position in the mechanism along 
a loading path and then moved into operative position in the mechanism 
along a firing path by a firing cylinder. These are commonly known as 
sequential type valve mechanisms. One configuration of these sequential 
type valve mechanisms both loads and fires the slide gates along a common 
path. Examples of this valve mechanism configuration are illustrated in: 
______________________________________ 
U.S. Pat. No. 
Inventor Issue Date 
______________________________________ 
Re. 27,237 J. T. Shapland 
November 23, 1971 
3,436,023 A. Thalmann April 1, 1969 
3,454,201 P. C. McShane April 1, l969 
3,866,806 E. P. Shapland 
February 18, l975 
______________________________________ 
Another configuration of such sequential type valve mechanisms loads the 
slide gates along a loading path and then fires the slide gate into 
position along the firing path, perpendicular to the loading path. Example 
of this valve mechanism configuration are disclosed in: 
______________________________________ 
U.S. Pat. No. 
Inventor Issue Date 
______________________________________ 
4,415,103 E. P. Shapland, et al. 
November 15, l983 
4,545,512 E. P. Shapland, et al. 
October 8, 1985 
______________________________________ 
This latter configuration typically uses a running gate with the hole, 
through which the molten metal flows, offset from the center of the gate. 
The offsetting of the hole facilitates throttling molten metal flow 
through the valve mechanism by moving the running gate laterally of the 
firing axis. The metal flow hole through the shroud plate in this 
configuration is typically centered on the metal flow hole through the top 
plate during operation. Both the running gate and shroud gate are 
typically rectilinear with a slightly greater length in one direction than 
in the other. Thus, these gates can be reversed as they are loaded into 
the valve mechanism. 
The fact that the running gate can be reversed has posed problems over the 
years since inadvertently reversing the running gate has immediate and 
disastrous results. This is because the valve mechanism is typically set 
to a closed position during gate change and reversing the running gate 
installs the new gate in an almost fully open position. Further, a 
reversed gate causes the valve mechanism to operate backwards. That is, 
when the running gate is reversed, the normal fully open position is the 
fully closed position and the normal fully closed position is the fully 
open position. In addition, a reversed running gate prevents making any 
gas connections normally made directly to the running gate so that the 
molten metal being poured is typically downgraded to a less desirable 
grade of steel. 
A reversed shroud gate may prevent making those gas connections normally 
made directly to the shroud gate or tubular shroud and cause a downgrading 
of the molten metal being poured. 
SUMMARY OF THE INVENTION 
These and other problems and disadvantages associated with the prior art 
are overcome by the invention disclosed herein by providing a means for 
assuring the proper orientation of the running gate and shroud gate in a 
sequential type valve mechanism or any other type of similarly loaded 
valve mechanism. The gates are physically prevented from being loaded into 
the valve mechanism to the loaded position for firing unless the gate is 
correctly oriented. 
The apparatus of the invention includes different thickness shoulders along 
opposite side of the gate and a pre-positioning guide with a gauging 
opening therethrough complementary to the cross-sectional shape of the 
gate so that the gate will pass into the valve mechanism only when the 
gauging opening matches the shoulders on the gate. Thus, the gate can be 
loaded with only one orientation, Preferrably the thin shoulder on the 
gate is stepped so that the valve mechanism does not have to be internally 
modified.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
The gate safety arrangement of the invention is designed for use with 
either or both the running gate and the shroud gate in a conventional 
sequential type slide gate valve mechanism SGVM used to control the flow 
of molten metal from vessels. While such valve mechanisms SGVM may be used 
on either tundishes or ladles, they are most typically used on tundishes 
and the arrangement of the invention is illustrated mounted on a tundish 
TUN. 
The valve mechanism SGVM with which the invention is illustrated is a 
sequential type slide gate valve mechanism such as that shown in U.S. Pat. 
No. 4,545,512, the disclosure of which is incorporated herein by 
reference. The valve mechanism SGVM is typically mounted on a tundish TUN 
as seen in FIG. 1. Basically, the valve mechanism SGVM as seen in FIG. 1 
includes a valve frame VF mounting a firing cylinder assembly FCA on one 
end and a pair of throttling cylinder assemblies TCA on opposite sides. 
The throttling cylinder assemblies TCA mount a guide rail assembly GRA 
within the frame VF to slidably support the running gates as will become 
apparent. 
The main frame VF is generally horizontal during use and has an operating 
opening OO extending longitudinally through it along operating path 
P.sub.O. A loading opening LO extends through frame VF along the loading 
path P.sub.L perpendicular to operating path P.sub.O. Since the loading 
opening LO extends completely through the frame VF, the gates can be 
loaded from either side of the frame. 
As best seen in FIG. 1, the frame VF has a pair of running gate loading 
rails RGLR that extend along opposite sides of the loading opening LO 
intermediate the height of the opening and a pair of shroud gate loading 
rails SGLR that extend along the loading opening LO below the running gate 
loading rails RGLR. Once that end of the loading opening LO to be used for 
the installation of the gates is selected, the opposite end of the opening 
LO is closed by a conventional stuffer member STM as seen in FIG. 1. The 
stuffer member STM serves to arrest the movement of the shroud gate as it 
is loaded into the valve mechanism along the loading opening LO. 
The safety gate arrangement 10 best seen in FIGS. 2-6 includes a running 
gate 11 and a pre-positioning guide assembly 12 operatively associated 
with the gate 11 to permit the gate to loaded into the valve mechanism 
SGVM only when the gate is properly oriented. The safety gate arrangement 
10 may also be used to load the shroud gate assembly 14 as will become 
apparent. 
The running gate 11 corresponds to the refractory slide plate in U.S Pat. 
No. 4,545,512. The rectilinear gate 11 includes a running gate ceramic 15 
mounted in a metal retainer 16 with mortar 18. The metal retainer 16 has a 
loading central axis A.sub.L and a firing central axis A.sub.F normal to 
the loading central axis A.sub.L. The retainer 16 has a pair of generally 
L-shaped side walls 19.sub.TN and 19.sub.TK parallel to the loading 
central axis A.sub.L joined by a pair of L-shaped end walls 20 parallel to 
the firing central axis A.sub.F. Each of the side walls 19 and end walls 
20 join with a depending bottom lip 24 at their inner ends. The metal 
retainer 16 thus defines an upwardly opening ceramic receiving recess 
therein. 
The side wall 19.sub.TN has a stepped section 25 formed therein defining a 
downwardly opening step recess 26 along the length of the side wall 
19.sub.TN and through the side walls 20. The step recess 26 opens onto the 
bottom of the gate 11 and also onto the side edge of the gate along the 
thinner side wall 19.sub.TN as seen in FIGS. 3 and 4. The recess 26 is 
parallel to the outside side edge 21 of the wall 19.sub.TN and has a 
transverse width W.sub.GR less than the distance from the lip 24 to the 
side edge 21. This produces a thinner section 23 adjacent the side edge 21 
of the gate 11 and a thicker section 27 spaced inwardly of the side edge 
21 the distance W.sub.GR. 
The running gate ceramic 15 conforms generally to the ceramic receiving 
recess in the metal retainer 16 with a mortar space in between. A 
clearance recess 28 is provided along the bottom of that side of the 
ceramic 15 overlying the recess section 25 in the thinner side wall 
19.sub.TN of retainer 16. The ceramic 15 defines a metal flow passage 29 
therethrough which is offset from the firing central axis A.sub.F along 
the loading central axis A.sub.L as is typical for throttling running 
gates. The passage 29 may be formed in a refractory insert 30 positioned 
in the ceramic 15. The difference between the ceramic 15 and the prior art 
is the recess 28. The ceramic 15 defines an upper sealing surface 31 
thereon to the plane defined by the axes A.sub.L and A.sub.F and a lower 
sealing surface 32 parallel to the surface 31. These surfaces from seals 
in the valve mechanism SGVM during metal pouring. 
The gate 11 has an overall working height h.sub.W defined by the sealing 
surfaces 31 and 32. A thin shoulder height h.sub.TN is defined between the 
upper sealing surface 31 and the bottom surface 21 on the recess section 
25 while a thick shoulder height h.sub.SH is defined between the bottom 
surface 22 on the thicker section 27 of side wall 19.sub.TN and the upper 
sealing surface 31 as best seen in FIG. 4. The valve mechanism SGVM is 
internally designed to support gates 11 which have a shoulder height 
h.sub.SH. Because the thicker section 27 still has the height h.sub.SH, it 
is not necessary to internally modify the loading rails RGLR in the 
mechanism SGVM to support the gate 11. The height h.sub.TN is used as a 
gauge to control the orientation of gate 11 as will become more apparent. 
The pre-positioning guide assembly 12 is mounted on the valve frame VF 
around the entrance to the loading opening LO as best seen in FIG. 1 and 
cooperates with the recess 26 in the retainer 16 of the gate 11 to permit 
the loading of the running gate 11 only when it is properly oriented. The 
guide assembly 12 includes a base member 35 which is removably attached to 
the valve frame VF, a pair of running gate guide angles 36 mounted on the 
base member 35 in registration with the running gate loading rails RGLR on 
the frame VF, and a pair of shroud gate guide angles 38 mounted on the 
base member 35 in registration with the shroud gate loading rails SGLR on 
the frame VF. 
The base member 35, best seen in FIGS. 2 and 5, has a general inverted 
U-shape with a top section 39 and a pair of depending legs 40 integral 
with opposite ends of the top section 39. The base member 35 defines a 
loading opening 41 therethrough corresponding to the cross-sectional shape 
of the loading opening LO in the frame VF. The base member 35 is attached 
to the frame VF around the entrance of the opening LO with attachment 
bolts 42 as best seen in FIG. 1. 
As best seen in FIG. 2, each leg 40 includes a running gate loading tab 44 
which projects into the loading opening 41 to support the running gate 11 
while it is being checked for orientation. The two loading tabs 44 are 
horizontally aligned across the loading opening 41 and are axially aligned 
with the two running gate loading rails RGLR in the frame VF. The lower 
end of each of the legs 40 mounts a shroud gate loading flange 45 which 
projects into the loading opening 41 at a position spaced below the 
associated loading tab 44 so that the shroud gate will be supported. The 
two loading flanges 45 are also horizontally aligned across the loading 
opening 41 and are axially aligned with the two shroud gate loading rails 
SGLR in the frame VF. 
The top section 39 defines a pair of depending gauging tabs 46 thereon 
facing the running gate loading tabs 44 and spaced thereabove a gaugeing 
distance d.sub.RG. This distance is substantially equal to the running 
gate shoulder height h.sub.SH so that the running gate 11 will just clear 
the gauging tabs 46 when the bottom surfaces of the retainer side walls 19 
are resting flat on the upper surfaces 48 of the loading tabs 44. Thus, if 
the gate is not lying flat on the tabs 44, the gate 11 will not pass 
through the loading opening 41. The inside edges 49 of legs 40 form the 
sides of the opening 41 and are spaced apart the distance d.sub.SO 
corresponding to the overall gate width W.sub.RG. 
As best seen in FIG. 5, each of the running gate guide angles 36 includes 
an inwardly directed bottom support flange 50 and an upstanding side guide 
flange 51 along the outside edge of the flange 50. The flanges 50 are 
parallel to each other and spaced apart an opening distance d.sub.FO at 
their inside edges. The distance d.sub.FO is selected so that the inside 
edges of flanges 50 just clear the depending bottom lips 24 on the gate 11 
when the bottom surfaces on gate 11 are supported on the upper support 
surfaces 52 on flanges 50 as seen in FIG. 6. The distance d.sub.SO between 
the inside surfaces 54 of side flanges 51 corresponds to the gate width 
W.sub.RG so that the flanges 51 laterally guide the gate 11 along the 
loading path P.sub.L with the loading axis A.sub.L of gate 11 in vertical 
registration with loading path P.sub.L. 
The angles 36 are arranged so that the support surfaces 52 are coplanar 
with the upper surfaces 48 on the loading tabs 44 on base member 35. In 
like manner, the inside surfaces 54 on flanges 51 are coplanar with the 
inside edges 49 on the base member 35. 
Each of the shroud gate guide angles 38 includes an inwardly directed 
bottom support flange 60 and an upstanding side guide flange 61 along the 
outside edge of the flange 60. The flanges 60 are parallel to each other 
and support the gate assembly 14 on their upper support surfaces 62. The 
distance between the inside surfaces 64 of side flanges 61 corresponds to 
the width of the shroud gate assembly 14 so that the flanges 61 laterally 
guide the gate assembly 14 along the loading path P.sub.L with the loading 
axis A.sub.L of gate assembly 14 in vertical registration with loading 
path P.sub.L as will become more apparent. 
The angles 60 are arranged so that the support surfaces 62 are coplanar 
with the upper surfaces 65 on the loading flanges 45 on base member 35. In 
like manner, the inside surfaces 64 on flanges 61 are coplanar with the 
inside edges 49 on the base member 35. 
To insure that the running gate 11 can be loaded in only one orientation, a 
locating step 70 is provided on the locating tab 44.sub.TN as seen in FIG. 
2. The step 70 projects above the upper surface 48 of the tab 44.sub.TN 
and defines an upper gauging surface 71 thereon parallel to and spaced 
below the gauging tab 46 a distance d.sub.TN seen in FIG. 5. The locating 
step 70 has a cross-sectional size and shape which are complementary to 
that of the recess 26 in gate 11 so that the bottom surface on retainer 16 
can lie against the upper surface 52 on angle 36 only when the step 70 
lies within the recess 26 in gate 11. Thus, the gate 11 will only pass 
through the base member 35 when the gate 11 is in its one correct 
orientation. While this may be changed, the location for recess 26 and 
step 70 shown is designed to orient the hole end 34 on gate 11 leading the 
gate into the frame VF as illustrated in FIG. 2. The gate 11 can be 
reversed simply by using a guide assembly 12 with the step 70 on the 
opposite tab 44. While the step 70 is illustrated as located on the tab 
44, the length and location thereof is not critical as long as it is 
located close enough to the gauging tab 46 to raise the gate 11 so that it 
will not pass under the tab 46 if the recess 26 is not in registration 
with the step 70. 
The recess/step combination may be located at other positions on the gate 
11 and on the pre-positioning guide assembly 12. Likewise, this 
combination may be applied to the shroud gate 14 and work the same as for 
the gate 11.