Title of Invention

TUNDISH IMPACT PAD

Abstract 57) Abstract: A tundish impact pad (20) to reduce turbulence in the tundisli comprises a body of refractory material capable of withstanding contact with molten steel in a tundish (10), the body comprising a base (22) having an impact surface (24), an outer sidewall (26, 40) extending upwardly from the impact surface (24), a top surface (32) connected to the sidewall (26, 40) and defining an opening (30) therein, in which the top surface (32) has an inner annular portion (42) substantially parallel the impact surface (24), and the sidewall (26, 40) has an interior face (28) which is substantially perpendicular to the impact surface (24) and wherein a substantially right angle corner (28A) is provided between the sidewall (28) and the impact surface (24) and a substantially right angle corner is provided between the sidewall (28) and the top surface inner annular portion (42). PRICE: THIRTY RUPEES.
Full Text

This invention relates to a tundish impact pad, i.e. a pad of erosion resistant material positioned on the floor of a tundish to receive the incoming stream of molten metal poured into the tundish from a ladle.
U.S. patent 5169591 discloses an impact pad for a tundish for continuous casting of steel that comprises a base, a peripheral top surface and a discontinuous sidewall extending between the base and the peripheral top surface, the sidewall having an undercut inner surface, which may be curvilinear.
U.S. patent 5358551 discloses an impact pad which comprises a base, a sidewall extending around the base, the sidewall having an inner surface having a portion which extends inwardly and upwardly. That inner surface may be concave.
Whereas both of the aforesaid types of impact pad are designed to reduce turbulence in the tundish, we have surprisingly found that improved turbulence reduction can be achieved by providing an impact pad with internal comers defined between its base, its peripheral wall and its upper surface. Thus, we have now found that it can be advantageous to provide such internal comers and that improvements in the reduction of surface turbulence, minimisation of slag entrainment, prevention of break-up of tundish flux cover, reoxidation of the molten steel and ensuring a proper flow path of the steel within the tundish, may be achieved.

Accordingly, in one aspect, the invention provides a tundish
impact pad comprising a body of refractory material capable of
withstanding contact with molten steel in a tundish; the body
comprising a base having an impact surface, an endless outer sidewall
extending upwardly from the impact surface, a top surface connected to
the sidewall and defining an opening therein, the top surface having an
inner annular portion substantially parallel to the impact surface and
the sidewall having an interior face which is substantially perpendicular
to the impact surface and wherein a substantially right angle comer is
provided between the sidewall and the impact surface and a
inner substantially right angle comer is provided between the/sidewall and
the top surface inner annular portion.
Molten steel entering through the opening and contacting the impact surface flows outwardly then is turned inwardly by the sidewall interior face and then flows out the opening.
Preferably the sidewall is endless, i.e. it extends continuously around the impact surface.
Preferably, the opening is non-uniform in that it has a long dimension and a short dimension perpendicular to the long dimension. Thus it may be, for example, rectangular or oval.
The top outer surface of the pad may conveniently also be parallel to the impact surface.
The impact pads of the present invention uniformly disperse the flow of incoming steel rather than merely redirecting it.

Since the steel flow can be dispersed over a larger area than if a circular or other uniform configuration were used, the result is more uniformly surface directed flow while maintaining the benefits of reduced splash and turbulence. Also due to the non-uniform configuration of the impact pad it presents a larger "target" to the incoming steel than a similar width uniform shaped pad (e.g. circular or square), with the desired results obtained even if the steel stream is imperfectly aligned with the centre of the impact pad.
The invention is particularly useful in providing improved residence time distribution parameters in the poured molten steel. It can also be of reduced cost due to its simplified internal chamber shapes and may be of reduced overall size relative to known impact pads.
The impact pads according to the present invention are formed of a refractory composition which is capable of withstanding continuous contact with molten metal, in particular, molten steel such as used in continuous casting operations. Usually a standard medium-to-high alumina monolithic refractory, with an alumina content in the range of about 55 to 85% by weight is desirable. Where a basic refractory is preferred because of steel chemistry, it is preferred that a magnesia based monolithic refractory be utilised, with MgO in the range of about 58 to 93% by weight.
In another aspect the invention provides a tundish for holding a volume of molten steel and having a floor and side walls enclosing a region of impact and a drain, an impact pad of the present invention being provided on the floor of the tundish in the region of impact.

Accordingly the present invention provides a tundish impact pad comprising a body of refractory material capable of withstanding contact with molten steel in a tundish, the body comprising a base having an impact surface, an outer sidewall extending upwardly trom the impact surface and a top surface connected to the sidewall and defining an opening therein. the top surface having an inner annular portion substantially parallel to the impact surface, and the sidewall having an interior face which is substantially perpendicular to the impact surface wlierein a substantially right angle comer is provided between the interior sidewall face and the impact surface and a substantially right angle comer is provided between the interior sidewall face and the top surface inner annular portion .

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:
Figure 1 is a side cross-sectional view of a tundish including an impact pad of the invention disposed on the floor of the tundish;
Figure 2 is a top plan view of the impact pad of Figure 1, which illustrates where the cross-section of Figure 1 is taken (along line I to I);
Figure 3 is a cross-section along line III to III of Figure 2; and
Figure 4 is an enlarged sectional view of a portion of the impact pad of Figure 3.
In Figure 1, a conventional tundish 10 is shown and includes an inner lining 12 and a pair of well blocks or outlets 14 to allow molten metal (typically steel) from a bath 16 contained in the tundish 10 to continuously exit the tundish 10 and enter moulds (not shown) which form metal castings. As is also conventional, a ladle shroud 18 or like tundish filling device, is positioned above the tundish 10 and continuously directs a stream of molten metal into the tundish 10. A tundish impact pad 20 constructed according to the present invention is placed generally centrally on the floor 15 of the tundish 10.
As seen in Figures 1 to 4, the tundish impact pad 20 is preferably rectangular in shape and is positioned with its longer sides parallel to the longitudinal axis of the tundish. The pad includes a base

22 having a planar, horizontal, impact surface 24. The pad 20 further includes an endless, annular outer sidewall 26, 40 having an inner wall face surface 28. The impact pad 20 also has a top surface 32 parallel to the impact surface 24 and connected to the sidewall 26, 40 and defining a non-uniform opening 30 therein. By "non-uniform" it is meant that the opening 30 is not circular or square; rather it has a long dimension 30' (see Figure 2) and a short dimension 30" substantially perpendicular to the long dimension 30'.
As seen in all of Figures 1 through 4, the interior face 28 of the sidewall extends upwardly substantially at right angles to the impact surface 24 around the entire periphery thereof. The continuous nature of the inner surface 28 is perhaps seen most clearly in Figure 2, being shown in dotted line therein.
inner As shown in Figures 3 and 4, the^sidewall 28, with impact
surface 24 and underside portion 42 of top surface 32, provides two
sharp comers 28A and 28B respectively, which comers also extend
continuously around the inside of the impact pad.
As seen in Figure 1, the outer sidewall 26 may be tapered inwardly from the top surface 32 toward the base 22, defining ears 27 at opposite ends. The ears 27 facilitate connection of the impact pad 20 to the base or floor 15 of the tundish when certain types of tundishes are utilised. Alternatively, the impact pad 20 may merely be mounted in a conventional manner on the bottom of the tundish.
It is also noted that the bottom portion of the top surface 32 has annular portions 39, 42 (see Figure 3) thereof, which lie parallel to the impact surface 24. This annular, overhang surface 42 facilitates

proper directing of the molten steel during filling of the tundish 10. Note that the long dimension 30' of the opening 30 is positioned aligned with the long dimension of the tundish (the dimension between the outlets 14, as seen in Figure 1), whereas the short dimension 30" of the opening 30 is aligned with the short dimension of the tundish 10.
The outer sidewall portions 40, rather than being tapered inwardly like the sidewall portions 26, preferably taper very slightly (e.g. 2 to 5°) outwardly, as seen in Figure 3. Alternatively, straight sides may be provided for both walls 26, 40 and straight sidewalls 26 may or may not contain ears 27,
The refractory material of which the impact pad 20 is made must be capable of withstanding continuous contact with molten steel during the entire use cycle of the tundish 10. It must have adequate refractoriness normally available from a standard medium-to-high alumina monolithic refractory. For example, an alumina content in the range of about 55 to 85% may be utilised. Where a basic refractory is preferred because of the steel chemistry, typically an MgO-based monolithic refractory, with MgO in the range of about 58 to 93% is preferred.
While it is preferred that the impact pad 20 be rectangular in shape, as illustrated in Figures 1 through 4, other non-uniform configurations can also be provided. For example, an oval impact pad may be utilised, or another type of multi-sided polygon configuration, as long as there is an opening with a long dimension which is aligned with the long dimension of the tundish 10 and a short dimension aligned with the short dimension of the tundish 10.

In use of the tundish pad 20 illustrated in Figure 1, molten steel flowing in the path 34 from a location disposed above the pad 20 strikes the impact surface 24 and then moves radially outwardly as illustrated by arrows 35. When the steel impacts the inner face 28 of the sidewall, it is directed inwardly then upwardly, flowing as illustrated at 36 in Figure 1 and ultimately being dispersed generally radially outwardly as indicated by arrows 37, 38 in Figure 1. This minimises turbulence on the surface of the bath 16 and helps direct slag and other impurities away from the stream 34.
It is not essential that the comers shown in dotted line in plan in Figure 2 be radiused as shown and the comers may, if desired, be right-angled.
If desired, small comer fillets may be present in the right-angle comers between the sidewall and the impact surface and/or the top surface inner annular portion.


WE CLAIM:
1. A tundish impact pad comprising a body of refractory material capable of withstanding contact with molten steel in a tundish, the body comprising a base (22) having an impact surface (24), an outer sidevvall extending upwardly from the impact surface (24) and a top surface (32) connected to the sidewall (26. 40) with an opening (30) therein, the top surface (32) having an inner annular portion (42) substantially parallel to the impact surface, and the sidewall (26. 40) having an interior face (28) which is substantially perpendicular to the impact surface (24) wherein a substantially right angle corner (28A) is provided between the interior sidevvall face (28) and the impact surface and a substantially right angle corner is provided between the interior sidewall face (28) and the top surface inner annular portion (42).
2. The tundish impact pad according to Claim 1, wherein said )pening has a long dimension and a short dimension perpendicular to the 3ng dimension.
3. The tundish impact pad according to Claim 2. wherein said
pening is rectangular or oval.
4. The tundish impact pad according to Claim 1, 2 or 3, wherein e top outer surface of the pad is parallel to the impact surface.
5. The tundish impact pad according to any one of the preceding aims, wherein the sidewall is endless.

6. The tundish impact pad according to any one of the preceding
claims, wherein the pad is a monolithic retractory having an alumina content
of from 55% to 85% by weight.
7. The tundish impact pad according to any one of claims 1 to 5.
wherein the pad is a monolithic refractor^' comprising magnesia and
contaniing from 58•^J to 93*^0 b\ weight of magnesia.
8 /\ tundi.^h with an impact pad as claimed in an\ one of the preceding claims,
9. A tundish impact pad comprising a body of refractor} material substantially as herein described with reference to the accompanying drawings.


Documents:

1422-mas-95 abstract.pdf

1422-mas-95 claims.pdf

1422-mas-95 correspondence others.pdf

1422-mas-95 correspondence po.pdf

1422-mas-95 description (complete).pdf

1422-mas-95 drawings.pdf

1422-mas-95 form-1.pdf

1422-mas-95 form-26.pdf

1422-mas-95 form-4.pdf

1422-mas-95 form-6.pdf

1422-mas-95 form-9.pdf

1422-mas-95 petition.pdf


Patent Number 193003
Indian Patent Application Number 1422/MAS/1995
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date 16-Mar-2005
Date of Filing 02-Nov-1995
Name of Patentee M/S. FOSECO INTERNATIONAL LIMITED
Applicant Address 285, LONG ACRE, NECHELLS BIRMINGHAM, B7 5JR, A BRITISH COMPANY, ENGLAND
Inventors:
# Inventor's Name Inventor's Address
1 DONALD RICHARD ZACHARIAS 285, LONG ACRE, NECHELLS BIRMINGHAM, B7 5JR, A BRITISH COMPANY, ENGLAND
PCT International Classification Number B22D23/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA