US3492171A - Method for forming a tap hole in a wall portion of a metallurgical furnace containing molten metal - Google Patents

Description

Jan.' 27, 1970 w. REscH ET AL METHOD FOR FORMING A TAP HOLE IN A WALL PORTION OF A METALLURGICAL FU Original Filed June 9. 1966 RNACE CONTAINING MOLTEN METAL 5 Sheets-Sheet 1 r ww V.. IHM? Jan.' 27,1970 w. RescH am 314A9z,1.11

NACE CONTAINING MOLTEN METAL METHOD FOR FORM-ING 4A TAP HOLE IN A WALL PORTION METALLURGICAL FUR Original Filed June 9. 1966 3 .Sheets-Sheet 2 WEA/7a? 'Jem/En @asm Jan. 27, 1970 w. RSCH rAL 3,492,171 METHOD Foa FORMING A TAP HOLE IN A WALL PORTION oF A METALLURGICAL FURNAE CONTAINIG MOLTEN METAL Origlnal Filed June 9. 1966 5 Sheets-Sheet 5 @um Flegg 472, um L JM.

Mrw() United States Patent O Int. c1. Bzsk 7/00 U.S. Cl. 148-9 7 Claims ABSTRACT OF THE DISCLOSURE A method of forming a tap hole in a wall portion of a metallurgical furnace in which the tap hole is prebored to a predetermined depth by mechanical boring means and in which the remainder of the tap hole is burned through by means of an oxygen blowpipe.

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a divisional application of the application tiled with the Ser. No. 556,506 on June 9, 196'6, now Patent No. 3,450,399.

BACKGROUND OF THE INVENTION The present invention relates to a method for forming a tap hole in a wall of a metallurgical furnace containing molten metal.

In known methods of this type, the. tap hole is prebored to a predetermined depth either by hand or by an appropriate boring machine and the remainder f the tap hole is burned through by means of an oxygen blowpipe.

In carrying out this method as known in the art, the operator handling the blowpipe has to stand laterally of the tap hole and at a considerable distance from the outer end thereof so that it is extremely difficult for him to guide the blowpipe coaxial with the prebored portion of the tap hole. This may result that the final portion of the tap hole will be located inclined to the theoretical axis thereof, which in turn may result in damage of the wall portion of the furnace about the tap hole by the hot molten metal emanating therefrom. In addition there iS the danger that the blowpipe is introduced too far ntO the furnace in direction inclined to the axis of the tap hole so that damage of the furnace wall about the tap hole during the burning operation may result. In carrying out such a method there is also always the danger that the operator may be'injured by the stream of molten metal emanating from the opened tap hole, especially when the stream of metal impinges on the blow pipe.

In order to overcome these disadvantages, methods and boring apparatus have already been developed in which opening of the tap hole is carried out only by mechanical means, which may even be remotely controlled, so that the tap hole will always be formed over its whole length at the saine exactly adjusted angle. The forming of the tap hole is in this case carried out in two steps, in the first step the tap hole is bored out to a predetermined depth, whereas during the second Step the remainder of the tap hole is formed by a percussion drill.

This known method is not very well suited for the forming of tap holes in open hearth furnaces, especially in Siemens-Martins ovens, since in such furnaces the final opening of the tap hole is in the most cases only possible by means of an oxygen blowpipe. The aforementioned method has also the disadvantage that the second tool has to be moved, after the tap hole has been completely opened and the molten steel emanates in a stream therefrom, at least through the length of the tap hole in direction of the emanating stream of molten steel and that only after the second tool has been withdrawn in this direction, the whole machine may be moved in direction transverse to the stream of emanating steel out of the iniluence of the latter. During the time of withdrawal of the second tool in axial direction the machine is subjected to the influence of the hot molten steel emanating from the opened tap hole so that damage to the tool and to the machine are hardly avoidable and so that replacement of the second tool and/or repair of the machine will become necessary after only a few operations.

This known method has therefore also not worked out to full satisfaction, especially since in modern furnaces the period between successive tappings of the furnaces are considerably reduced so that methods and apparatus for forming the tap holes without damage to the apparatus become of increasing importance.

It is an object of the present invention to provide for a method for forming tap holes in a furnace which avoids the above-mentioned disadvantages of methods known in the art.

It is an additional object of the present invention to provide for a method for forming tap holes in a furnace in which the danger of damaging the apparatus carrying out the method by the hot metal emanating from the tap hole is reduced to a minimum.

It is a further object of the present invention to provide a method for forming a tap hole in a furnace by pre-boring the tap hole rst to a predetermined depth and by burning out the remainder of the tap hole by an oxygen blowpipe and in which the appartus may be moved in direction transverse to the stream of hot metal at the moment the hot metal emanates from the furnace.

SUMMARY OF THE INVENTION With these objects in view, the method according to the present invention for forming a tap hole in a wall portion of a metallurgical furnace containing molten metal, mainly comprises the steps of advancing a boring tool in a predetermined direction against the wall portion of the furnace for boring a tap hole to a predetermined depth in the wall portion, retracting the boring tool out of the bored wall portion, advancing a blowpipe in said direction through the prebored portion of the tap hole, burning through the remainder of the wall portion by means of oxygen blown through the blowpipe, and cutting off the front portion of the blowpipe at the moment of finishing the tap hole to the full depth thereof and discharge of molten metal through the opened tap hole from the furnace, so that a common carrier mounting the boring tool and the blowpipe may be moved in a direction transverse to the path of molten metal emanating from the furnace at the moment of cut-off of the front portion of the blowpipe. This method will assure that the complete tap hole will extend through the wall portion of the furnace in the predetermined direction and the method has the further advantage that the carrier which carries the boring tool and the blowpipe may be removed out of the danger zone at the exact moment at which the molten metal emanates from the furnace. The cost of the cut-olf portion of the blowpipe is negligible as compared to the advantages derivable from this method which will assure that damage to the remainder of the apparatus during repeated operations is completely avoided. Preferably, the method includes also the step of sensing discharge of molten metal from the opened tap hole 3 and automatically controlling cut-off of the end portion of the blowpipe and movement of the common carrier in dependence on the sensed discharge of molten metal from the furnace.

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 FIG. l is a schematic partly sectioned side view of the apparatus of the present invention as mounted on a metallurgical furnace only partly shown in FIG. l;

FIG. 2 is a front View of the apparatus shown in FIG. 1, with some elements of the apparatus removed for the sake of clarity; and

FIG. 3 is a longitudinal cross section through part of the apparatus shown in FIG. 1 drawn to an enlarged scale and showing the boring means in the retracted position thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and more specifically to FIGS. l and 2 of the same, it will be seen that the apparatus according to the present invention comprises support means which preferably include a carriage 3 movably guided by means of rollers 3a in a pair of U-shaped guide rails 2 extending in substantially horizontal direction and being mounted in any convenient manner on a portion of a furnace 1, only partly and schematically illustrated in FIG. 1. The support means include further elongated guide means in form of a pair of tubular members 5 projecting spaced from and parallel to each other downwardly from a bottom wall of the carriage 3 and being connected at the upper ends thereof in any convenient manner, for instance by welding, to the latter. A pair of guide sleeves 5a are arranged spaced from each other on each of the tubular guide members 5 and the guide sleeves 5a are connected by cross bars 5b to an additional tubular member 6 located midway between the pair of tubular members 5 and extending with a lower portion thereof downwardly beyond the lower ends of the tubular members 5, as best shown in FIG. 2. A plug 6a is fixed, for instance by welding, in the lower portion of the tubular member 6, extending with a bottom portion thereof beyond the bottom end of the tubular member and this bottom portion is preferably of square or rectangular cross section. The bottom portion of the plug 6a is formed with a bore extending transverse to the axis of the tubular member 6 and a working head 9 having a pair of side walls 9 and 9" is tiltably mounted on the bottom portion of the plug 6a by means of a pin 6b extending through the aforementioned bore. Each of the side walls of the working head 9 is formed with a curved slot 9a substantially coaxial to the axis of the pin 6b through which screw bolts 9b ixed to the plug 6a extend so that nuts screwed onto opposite ends of the screw bolts may be used for fixing the working head 9 in a desired angular position with respect to the axis of the tubular member 6.

The working head 9 carries between the side walls 9' and 9" thereof elongated boring means movable in axial direction and rotatable about its axis. The elongated boring means comprise, as best shown in FIG. 3, an elongated tubular member 24 guided for movement in axial direction between a plurality of lower guide rolls 24a and an upper guide roll 24b turnably mounted between the side walls of the working head 9. Coaxially arranged within the tubular member 24 and turnable about its axis relative thereto is an elongated tubular boring member 17 formed at the front portion thereof facing the furnace 1 with appropriate cutting portions. During the actual boring operation, the front end of the tubular boring tool 17 is closed by plug 18 removably inserted in the front end thereof. The tubular boring member 17 is rotated about its axis by means of a motor 19 iixedly mounted on the rear end of the tubular member 24 and connected to the rear end of the boring tool 17 by means of a reduction gearing 20. The motor 19 is preferably a motor of known construction operated by compressed air. The tubular member 24 and the tubular boring tool 17 mounted therein for movement in axial direction therewith are advanced in axial direction by means of a rack 25 iixed to an upper portion of the tubular member 24 and meshing with a pinion 23 which is mounted on a rocker arm 22 pivoted at a front end thereof at 22 to the side walls of the working head 9 and carrying at the other end thereof a motor 21 of known construction, preferably driven by compressed air and connected to the pinion 23 by means of a belt or chain drive 21a so as to rotate the latter.

An elongated blowpiece 26 extendsy substantially coaxial through the interior of the tubular boring tool 17 and is slidably guided therein for movement in axial direction so that the front portion of the blowpipe 26 may, after the plug 18 is removed from the tubular boring tool 17, project beyond the front end of the latter. When the blowpipe 26 is formed from a substantially rigid tube, the latter may be moved in axial direction relative to the tubular boring tool 17 by means of an annular piston 27 fixed to a rear portion of the blow pipe and by compressed air acting on the piston 27.

On the other hand, the blowpipe may be formed from flexible tubing and the rear portion thereof may be wound on a spool and in this case the blowpipe may be advanced by turning the spool about its axis.

The apparatus includes further cutoff means for cutting off the portion of the blowpipe 26 projecting beyond the front end of the boring means 24, 17 when the latter are in the retracted position as shown in FIG. 3. The cutoff means include a cutoff knife 13, guided between a pair of guide plates 12 extending spaced from each other and transverse to the side plates of the working head 9, and being movable between a retracted position, as shown in FIG. 3, in which the cutting edge 14 of the cutting knife 13 is upwardly spaced from the tubular member 24 and a cutoff position in which the cutting edge 14 cuts through the end portion of the blow pipe 26 when the latter projects beyond the front end of the tubular member 24 through the guide plates 12. The cutoff knife 13 is moved between the positions thereof by operating means including cylinder and piston means 15 operated by compressed air and including a cylinder 15a pivotally mounted at one end thereof on the working head 9 and a piston 15b slidably guided in the cylinder 15a and having a piston rod projecting be yond the other end of the cylinder 15a and being pivotally connected to a plate-shaped lever 16 which in turn is pivotally mounted in the manner as best shown in FIG. 3 on the working head 9. The end of the lever 16 distant from the end connected to the piston rod of the piston 15b is connected by means of a pin and slot connection to the upper end of the cutoff knife 13, as shown in FIG. 3'. The cylinder and piston means 15 may also include a compression spring 15c mounted between the other end of the cylinder 15a and piston 15b in the manner as shown in FIG. 3 and being biased in such a manner so as to yieldably maintain the cutoff knife 13 in the retracted position as shown in FIG. 3. A tube or hose 15d, communicating with the interior of the cylinder 15a in the manner as shown in FIG. 3, serves to feed compressed air into the cylinder so as to move the piston 15b against the force of the compression spring 15e towards the left, as viewed in FIG. 3, to move thereby the cutoff knife 13 from the retracted to the cutoff position thereof. A valve 28 in the tube 15d controls ow of compressed air into and out of the cylinder 15a.

Biasing means are connected to be working head 9 for moving the latter from a working position in which the boring means 24, 17 are aligned with a portion of the furnace in which the tap hole is to be formed and an inactive positon in which the working head is displaced in direction transverse to the axis of the boring means from the working positon. The biasing means may include a pair of elongated weights 7 slidably guided in the tubular members 5 and connected by ropes 7a or the like to the transverse bars 5b which connect the guide sleeves 5a to each other. The ropes 7a are preferably guided over rollers 7b turnably carried by the carriage 3, as best shown in FIG. 2. 4The biasing means may also include a coil tension spring 8 xed. at opposite ends thereof to the carriage 3 and the upper end of the tubular member 6, which supports the action of the weights 7. Likewise, a weight 4 connected by means of a rope 4a or the like and guided over a roller 4b turnably mounted on the guide rails 2 is connected to thefarriage 3 so as to tend to move the latter in lateral direction so as to move the parts of the apparatus connected to the carriage 3 in horizontal direction away from a position in which the boring tool carried by the working head 9 is properly located with respect to the furnace 1.

The apparatus includes further locking means cooperating with the guide means or guide sleeves 5a and with the carriage 3 for maintaining the guide sleeves 5a and the part of the apparatus connected thereto as well as the carriage 3 against the forceexerted by the biasing means, that is the weights 7 and 4 and the spring 8 in a position in which the boring means carried by the working head of the apparatus are properly aligned with a predetermined Wall portion of the furnace. The looking means may include a locking pin 29 extending through appropriate aligned bores of one of the sleeves 5a and the corresponding tubular member 5 and moveable between a locking position as shown in FIG. 2 and a releasing position in which the pin 29 is removed from the bore in the tubular member 5 so that the sleeve 5a is free to move in upward direction under the influence of the biasing means connected thereto, The locking pin 29 is connected by a pin and slot connection to the upper end of a lever 30 pivotally connected yat a lower end to a lower portion of the tubular `vmember 5 and moved from the locking position to a releasing position in which the pin 29 is withdrawn from the bore in the member 5 by means of a rope 31 or the like which is guided over a roller 32 mounted on -the working head 9 and connected at the end opposite from the lever 30 to a lever 33 which is xed to the plate-shaped lever 16 for turning with the latter. A spring 34 connected to the lever 30 tends to maintain the locking pin 29 in the locking position thereof. A rope 35 or the like connects the lever 30 to an additional locking pin 36 projecting in the path of the carriage 3 to engage the left end of the path of the carriage 3 to engage the `left end of the latter, as viewed in FIG. 2, to prevent movement of the carriage 3 to the left, as viewed in FIG. 2, under the inuence of the weight 4. A spring 37 cooperates with the locking pin 36 tending to maintain the latter in the locking position as shown in FIG. 2. y

The apparatus may further include sensing means 38 of known construction arranged in the region of the wall portion of the furnace 1 in which the tap hole 10 is to be formed for sensing hot metal emanating from the tap hole. The sensing means may be lin' the form of an electric eye or in the form of temperature sensing means and the specific construction of the sensing means used does not form part of the present invention. The sensing means have to be constructed in such a manner so as to instantaneously sense when hot molten metal emanates from the tap hole 10. The sensing means 36 are connected in a known manner to the valve 28 to open the latter for feeding compressed air into the cylinder 15a so as to move the piston 15b in a direction which moves the cutting knife 13 from the retracted to the cutoff position thereof at the moment hot molten metal emanates from the finished tap hole.

The operation of the apparatus above described will be obvious from the description thereof. The angular position of the working head 9 relative to the tubular support thereof is first adjusted by means of the adjusting means 9a, 9b above-described, and the locking pins 29 and 36 are maintained in the engaged position so that the boring means 24, 17 are properly aligned with the wall portion of the furnace 1 in which the tap hole 10 has to be formed. The tubular boring member 17 is then rotated about its axis by means of the motor 19 and the tubular member 24 as well as the tubular boring tool 17 are advanced'from the position shown in FIG. 3 so as to engage a wall portion of the furnace 1 in which the tap hole 10 is to be formed and to bore this tap hole to a predetermined depth. The boring means 24, 17 are then retraced, by reversing the motor 21 in a known manner, again to the position shown in FIG. 3 and the plug 18 is removed from the front end of the tubular member 17. The blowpipe 26 is then advanced from the position shown in FIG. 3 to extend through the guide plates 12 and into the prebored portion of the tap hole 10 and the remainder of the tap hole is then burned out by feeding oxygen through the blowpipe 26. When the tap hole 10 is completely opened molten metal in the furnace will emanate therethrough, and the sensing means 38 will sense emanation of molten metal from the tap hole. The sensing means 38, when energized, will open the valve 28 so that the piston 15b is moved from the position shown in FIG. 3 to a position in which the cutoff knife 13 is moved in downward direction to cut off the portion of the blowpipe 26 extending beyond the right guide plate, as viewed in FIG. 3. During the movement of the piston 15b towards the left, as viewed in FIG. 3, the lever 33 connected to the lever 16 will turn in counterclockwise direction moving thereby the locking pins 29 and 36 to the releasing position so that the working head 9 is moved under the influence of the biasing means, that is the weights 7 and the spring 8, in upward direction, whereas the carriage 3 is moved under the influence of the weight 4 towards the left, as viewed in FIG. 2, so that the apparatus is vertically and horizontally moved relative to the stream of molten metal emanating from the tap hole 10.

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 methods for forming a tap hole in a Wall portion of a metallurgical furnace differing from the types described above.

While the invention has been illustrated and described as embodied in a method for forming a tap hole by preboring the tap hole to a predetermined depth and by burning out the remainder of the tap hole, 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 generic or specific aspects of this invention.

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

1. A method of forming a tap hole in a wall portion of a metallurgical furnace containing molten metal, comprising the steps of advancing a boring tool in a predetermined direction against the wall portion of the furnace for boring a tap hole to a predetermined depth in said wall portion; retracting the boring tool out of the bored wall portion; advancing a blowpipe in said direction through the prebored wall portion; burning through the remainder of the wall portion by means of oxygen blown through the blowpipe; and cutting off the front portion of the blowpipe at the moment of finishing the tap hole to the full depth thereof and discharge of molten metal through the opened tap hole from the furnace.

2. A method as set forth in claim 1 and including the step of mounting said boring tool and said blowpipe on a common carrier, and moving said common carrier out of the path of the molten metal emanating from the furnace at the moment of cutoff of the front portion of said blowpipe.

3. A method as set forth in claim 2, lwherein said common carrier is moved in vertical and horizontal direction out of the path of the stream of metal emanating from the furnace.

4. A method as set forth in claim 3, and including the step of sensing discharge of molten metal from the opened v tap hole and automatically controlling the cutoff of the end portion of the blowpipe and movement of said common carrier in dependence on the sensed discharge of molten metal.

5. A method as set forth in claim 1, wherein said boring tool is tubular and wherein said blowpipe is advanced through said tubular boring tool.

6. A method as set forth in claim 5, wherein said front portion of said blowpipe is cut off in the region of the front end of saidfboring tool.

7. A method as set forth in claim 1, wherein the step of cutting off said front portion of said blowpipe is carried out by moving a cutting knife transverse to the axis of said blowpipe.

References Cited UNITED STATES PATENTSA 1,872,410 8/1932 Coberly 148-9 L. DEWAYNE RUTLEDGE, Primary Examiner W. W. STALLARD, Assistant Examiner

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