US3507483A - Axially reciprocating screw conveyor means for closing tap hole - Google Patents

Description

April 21, 1970 w. RESCH EI'AL AXIALLY RECIPROCATING SCREW CONVEYOR MEANS FOR CLOSING TAP HOLE Filed 001:. 31. 1967 United States Patent 3,507,483 AXIALLY RECIPROCATING SCREW CONVEYOR MEANS FOR CLOSING TAP HOLE Werner Resch, Dortmund-Kirchhorde, and Oskar Fliege,

Dortmund, Germany, assignors to Hoesch Aktiengesellschaft, Dortmund, Germany Filed Oct. 31, 1967, Ser. No. 679,480 Claims priority, application Germany, Nov. 3, 1966, H 60 917 US. Cl. 26642 8 Claims ABSTRACT OF THE DISCLOSURE A screw conveyor extends with a front portion thereof into a hole in the masonry structure, and a rear portion extends outwardly beyond the structure. A feed for a hardenable mortar communicates with the rear portion and supplies thereto quantities of the mortar. Drive means is connected with the screw conveyor and serves to rotate the same whereby to convey the mortar from the rear portion towards the front portion and beyond the same into the hole, and for axially reciprocating the screw conveyor to thereby effect tamping of the mortar which has been conveyed into the hole.

BACKGROUND OF THE INVENTION The present invention relates generally to an apparatus for closing a hole in a masonry structure, and more particularly for an apparatus for closing the tap hole in a wall of an open hearth furnace.

The most commonly used method of making steel is the so-called open-hearth furnace process. Such openhearth furnaces are well known and need not be described in detail. For the purposes of the present invention it will be sufficient to point out that the furnace proper is a masonry structure usually of rectangular configuration, which is supported by steel buckstays which are united via steel struts and tie rods. When the heat has been mixture of such slag with the dolomite adversely influences the closure which is provided when the dolomite hardens, and therefore can bring with it the danger of steel break-out during operation of the furnace. Of course, it is clear that the dolomite cannot simply be loosely introduced but must be tamped and compacted to provide a proper plug when it hardens.

All of this is customarily accomplished manually and it is clear that this is hard and tiring work. In view of the fact that the condition and size of the tap hole frequently differ, and taking in conjunction this with the strenuousness of the closing operation, it will be clear that the quality of the closure which is obtained varies greatly from instance to instance. If, however, the closure permits molten steel to break out before the proper time is reached, this cannot only bring with it dangers to the operating personnel as already mentioned briefly, but will also result in a steel which is so inferior that it must be reintroduced into the furnace for re-melting. Evidently, this is time consuming and expensive, and reduces very significantly the effectiveness and economic operation of the furnace.

SUMMARY OF THE INVENTION The present invention overcomes the aforementioned disadvantages.

More particularly, the present invention provides an apparatus which is generally suitable for closing a hole in a masonry structure with a hardenable mortar and which is particularly suitable for closing the tap hole in the wall of an open hearth furnace.

The apparatus in accordance with the present invention is relatively simple in its construction and requires no significant economic or technological investments.

Furthermore the apparatus disclosed herein is highly reliable in its operation and eliminates the need for manual labor in closing the tap hole. What is more, the apparatus according to our invention does not require a skilled operator to supervise it.

By employing the apparatus disclosed herein closing melted and the finishing temperature is reached, the heat of steel is ready to be tapped, that is to be removed from the furnace. For this purpose the furnace is provided, usually midway between the ends of the hearth, with a so-called tap hole which, before the furnace is charged at the beginning of the heat, is filled with a suitable mortar, usually dolomite or a mixture containing this material. This filling must completely close the tap hole and prevent escape of molten steel therethrough until the heat is ready for tapping. Once this stage in the melting process has been reached the tap hole is opened, either by being burned out from the tapping side, that is the outer or exposed side of the furnace wall, or by a jet tapper consisting of a hollow explosive charge which concentrates its energy when discharged against the obstruction in the tap hole. The molten steel can now run out of the furnace.

In preparation for the next following heat, or more particularly for the next charge which precedes the heat, the tap hole is freed from steel which has chilled therein, raked out and cleaned of slag. Thereupon it must be closed up by introducing the dolomite mortar into the hole. This is customarily accomplished by having a helper manually introduce the coarse-grained dolomite mass into the tap hole, and by having another helper push the mass from the outer side towards the inner side of the tap hole. At the same time, additional dolomite is thrown against the inner end of the tap hole, that is the end within the furnace. Closing of the tap hole must be effected quickly to prevent slag remaining within the furnace from entering into the tap hole because a of the furnace tap hole can be effected more speedily and at less expense than heretofore known, and a closure of reliable and reproducible quality will be obtained in every instance. This eliminates the danger of premature break-out of the melt.

In accordance with one feature of our invention We provide an apparatus of the type set forth which includes a screw conveyor whose front portion is arranged to extend into the tap hole, and whose rear portion extends outwardly beyond the tap hole. A feed or supply is associated with the screw conveyor and supplies to the rear portion thereof quantities of hardenable mortar, namely dolomite or a dolomite-containing mixture. Finally, a suitable drive arrangement is connected with the screw conveyor and serves to rotate the same whereby the mortar is conveyed from the rear portion towards the front portion and beyond the same into the hole and further for axially reciprocating the screw conveyor to thereby periodically advance the front portion thereof into en-z gagement with the mortar which has been conveyed into the hole. By this expedient the mortar already in the hole is tamped and compacted.

Advantageously, a biasing means is provided which connects the apparatus with the masonry structure in which the hole is provided, and which is operative for urging the front portion of the screw conveyor deeper into the hole. We have also found it advisable to provide suitable cooling, for instance by means of a wateror otherwise fluid-cooled cooling jacket, for the screw conveyor.

With our apparatus we obtain a purely mechanical closure of the tap hole, eliminating thereby such factors as personnel fatigue and the like which, when manual closing of the tap hole is effected, have heretofore made is impossible to guarantee an absolutely tight closure of reproducable quality.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The single figure is a somewhat schematic sectional view illustrating one embodiment of our invention by way of example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing, in detail, it will be seen that the masonry structure, which will here be assumed to be the wall of an open-hearth furnace, is identified with reference designation MS. Provided in the wall MS is the tap hole TH which extends from the outer exposed side of the wall to the inner side, that is to the interior of the furnace. The metallic supports for the wall MS are generally identified with reference numeral 6.

The apparatus according to our invention comprises,

as is clearly evident from the drawing, a conventionally operating screw conveyor which includes the conveying screw 1 mounted for rotation within the tubular housing 4. Advantageously, the housing 4 can be cooled and for this purpose it is provided with a doub e wall which defines a cooling jacket for the flow of a coolant fluid, such as water, therethrough. The front portion of the screw conveyor extends, as illustrated in the drawing, into the tap hole TH, whereas the rear portion extends outwardly therebeyond. Feed means in form of a feed hopper 5 communicates with the rear portion in conventional manner, and it is clear from the drawing that, when the usually coarse-grained dolomite or dolomite-containing mortar is introduced into the hopper 5, it will enter the screw conveyor and when the conveyor screw 1 thereof is rotated, the conveyor from its point of entry towards the front end of the screw conveyor and the discharged therefrom into the tap pole TH.

The rear portion of the screw conveyor is further provided with an arrangement for reciprocating the conveyor screw 1. This arrangement is identified generally with reference numeral 2 and is of well known construction so that it need not be described specifically. It will sufiice to state that the two portions 2a and 2b of the arrangement 2 rotate with reference to one another when the conveyor screw 1 is rotated. The biasing spring which is shown in conjunction with the arrangement 2 tends to pass the facing surfaces of the members 2a and 2b into engagement. However, the facing surfaces are not planar but are rather of weavy configuration so that, on such rotation, the member 2a and the member 2b will alternately be separated from one another and be drawn back together by the biasing spring. This effects axial reciprocation of the conveyor screw 1, which is connected to the arrangement in well known manner and the screw 1 thus alternately rams against the mortar which it has just conveyed into the tap hole TH and thereby compacts and tamps the mortar. Power for rotation of the conveyor screw 1, and thereby also for the axial reciprocation thereof, is supplied by a suitable power means, here illustrated as a pneumatic motor 3 of conventional construction. By means of a cable or rope 8 shown in chain lines in the drawing, the arrangement is suspended from the hook 9 of a crane (not illustrated) which is provided for this purpose.

We have found it advantageous to connect and guide the arrangement with reference to the wall MS by pivoting a dash-pot 7, whose construction and operation will be self-evident, to the hopper 5 and to the frame 6 at the point 7a. Clearly, the dash-pot will tend to draw the arrangement, and of course thereby the front portion of the screw conveyor, deeper into the tap hole TH.

Operation of the device is of course obvious. Material supplied into the feed hopper 5 will be advanced into the tap hole TH when the motor 3 rotates the conveyor screw 1 and thereby axially reciprocates it at the same time. As the material is expelled from the front end of the screw conveyor, it is tapped and compacted by the repetitive engagement with the axially reciprocating conveyor screw 1. The dash-pot 7 constantly urges the screw conveyor deeper into the tap hole TH, and this force of course increased as the tap hole becomes more and more filled and the device is forced to withdraw from the tap hole to a greater and greater extent, thereby opposing the spring in the dash-pot 7. This, of course, in turn results in ever better compacting of the mortar in the tap hole TH.

It will be clear that by resorting to our herein disclosed apparatus the tap hole of an open-hearth furnace or for that matter any analogous hole in a masonry structure of a different type and application, can be reliably and tightly closed in a simple and most advantageous manner, and that these high-quality results which are ob tained are reproducible in every instance in which the same or another hole must be closed in this manner.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of devices differing from the types described above.

While the invention has been illustrated and described as embodied in an apparatus which is particularly suitable for closing the tap hole in the wall of an openhearth furnace, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art fairly constitute essential characteristics of the specific or generic aspects of this invention and therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. An arrangement for closing a hole in a masonry structure with hardenable mortar, comprising a furnace having a masonry wall provided with a hole; screw conveyor means including a conveyor screw having a front portion arranged to extend a substantial distance into the hole, and a rear portion arranged to extend outwardly beyond the hole and including also supply means associated with said conveyor screw and operative for supplying to said rear portion thereof quantities of hardenable mortar; actuating means connected with said conveyor screw for rotating the same whereby to convey the mortar toward said front portion and therebeyond into said hole; and means cooperating with said actuating means for axially reciprocating said conveyor screw to thereby periodically advance said front portion into engagement with the mortar in said hole and to tamp and compact such mortar.

2. Arrangement as defined in claim 1, wherein said hole extends inwardly from an exposed outer side of the wall of the furnace, and wherein all aforesaid means are arranged adjacent to said exposed side.

3. Arrangement as defined in claim 1, wherein said screw conveyor means comprises an outer tubular housing, and a conveyor screw mounted in said housing for rotary and axial movement therewithin.

4. Arrangement as defined in claim 3, wherein said outer tubular housing includes a cooling jacket arranged for circulation of a cooling fluid therethrough.

5. Arrangement as defined in claim 1, and further comprising maintaining means connecting the first-mentioned means in requisite position with reference to said masonry structure.

6. Arrangement as defined in claim 5, wherein said maintaining means comprises a biasing arrangement tending to urge said front portion deeper into said hole.

7. Arrangement as defined in claim 6, wherein said supply means is rigid with said rear portion of said screw conveyor means spaced from said masonry structure, said maintaining means including a cylinder connected at one end thereof with said supply means, a piston rod connected at a first end thereof with said masonry structure and extending with a second end thereof into the opposite end of said cylinder, and a biasing spring arranged 6 within said cylinder and tending to draw said piston rod deeper into said cylinder to thereby urge said supply means towards said masonry structure and said front portion of said screw conveyor means deeper into said hole.

8. Arrangement as defined in claim 7, wherein said cylinder and said piston rod are pivotably connected to said supply means and said masonry structure, respectively.

References Cited UNITED STATES PATENTS 1,774,373 8/1930 Hopkins et al 26642 2,090,434 8/1937 Thalmann 25-14 X 3,164,860 1/1965 OXel 25103 X ROBERT D. BALDWIN, Primary Examiner US. Cl. X.R. 25103

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