WO2005044492A1

WO2005044492A1 - Method and bore crown for drilling a hole, particularly a tap hole in a furnace

Info

Publication number: WO2005044492A1
Application number: PCT/AT2004/000381
Authority: WO
Inventors: Josef Mocivnik; Rene Egger-Mocivnik
Original assignee: Techmo Entwicklungs- Und Vertriebs Gmbh
Priority date: 2003-11-11
Filing date: 2004-10-29
Publication date: 2005-05-19

Abstract

In order to drill a tap hole in a furnace, using a bore crown (1) which comprises a plurality of projections (3,8) on the drilling surface thereof, said bore crown (1) is driven over a first partial area of the drill hole to be produced in a rotating movement and the bore crown (1) is driven in a rotating and percussive movement over the remaining length of the hole to be produced. Two different types of hard material (3,8) are provided on the drilling surface (2) of the bore crown (1). Hard material inserts (3), which have a larger extension from the drilling surface (2), cooperate with the material to be drilled, exclusively when the bore crown is rotated.

Description

METHOD AND DRILL BIT FOR DRILLING A HOLE, IN PARTICULAR A STITCH HOLE OF A BLAST FURNACE

The present invention relates to a method for drilling a hole, in particular a tap hole of a blast furnace, with a drill bit which has a plurality of hard material or hard metal inserts or cutting edges on its surface, and to a drill bit for drilling a hole, in particular a tap hole of a blast furnace, the drill bit being provided with a plurality of hard material or hard metal inserts or cutting edges.

Various embodiments are known in connection with the production of holes, in particular a tap hole of a blast furnace, a drill bit being removable, for example, in AT-U 6386, the aim being to properly transmit the drilling energy in order to achieve a correspondingly rapid drilling progress. In this known embodiment, essentially cylindrical hard material or hard metal inserts are fixed in a base body of a drill bit, it also being necessary to ensure that such hard material or hard metal inserts are not lost during the drilling process. In this known embodiment for producing a hole, in particular a tap hole of a blast furnace, the drill bit is subjected to both a rotating and striking movement in order to complete the hole or borehole, which usually has a comparatively small diameter, in short periods of time , A disadvantage of this known embodiment is in particular the fact that during the entire drilling process not only a rotating movement, but also an impact stress is exerted on the drill bit, so that the blast furnace is exposed to vibrations during the entire drilling process. Such vibrations can thereby impair or damage the lining of the blast furnace in particular and thus endanger the operating personnel.

The present invention aims to improve a method and a drill bit of the type mentioned at the outset in such a way that vibrations when drilling or producing a hole, in particular a tap hole of a blast furnace, are reduced or minimized.

In order to achieve these tasks, a method of the type mentioned at the outset is essentially characterized in that the drill bit is driven to rotate in a first part of the borehole to be produced and in that the drill bit is driven to rotate and strike over the remaining length of the hole to be produced becomes. By virtue of the fact that, according to the invention, the drill bit is driven only for a rotating movement at least over a first partial region of the hole or borehole to be produced, a corresponding protection of the object, in particular the blast furnace, in which the borehole or taphole is formed, is available be put. In connection with the production of a tap hole of a blast furnace, it can be assumed that after tapping has taken place, in particular in the partial region of the tap hole which is several meters long and connects to the interior of the blast furnace,

Remaining stocks of iron or iron-containing material are present in the tap hole, these remaining components being one with the stuffing material to be introduced into the tap hole Form inner part of the tap hole having higher strength or are designed similar to a reinforcement. In contrast, at the end facing the outer end of the tap hole, the hardened stuffing has a lower strength than the inner region, which has been reinforced or reinforced by the addition of iron or iron-containing constituents, so that even with drilling with only a rotating movement a corresponding drilling progress can be achieved. According to the invention, it is therefore proposed to dispense with the striking action of the drill bit, which supports drilling progress, during a first partial area of the production of the borehole, so that impairments and in particular vibrations in the area of the borehole or taphole are minimized.

Taking into account the achievement of sufficient drilling progress and the desired protection of the blast furnace during the production of a tap hole, it is proposed according to a preferred embodiment that the drive is carried out with a rotating movement over at least a third, preferably about half, the length of the borehole to be produced.

In order to ensure sufficient drilling progress while maintaining the blast furnace as much as possible by maintaining the largest possible partial area in which only a rotating movement is exerted by the drill bit, it is proposed according to a further preferred embodiment that the drilling progress is monitored during the rotating movement and that if the drilling progress falls below a predefined threshold value, an additional striking movement on the drill bit is practiced. This makes it possible to maintain the merely rotating loading of the drill bit over as long a period as possible and thus as large a part of the borehole as is to be made, while only after establishing the fact that when the merely rotating loading of the drill bit falls below a minimal or predefined drilling progress , in addition to continuing the drilling process on the drill bit, a striking movement or stress is exerted.

To achieve the above-mentioned tasks, a drill bit of the type mentioned at the outset is essentially characterized in that two different types of hard material or hard metal inserts are provided on the surface of the drill bit, with a greater extent of hard material inserts having the surface to be extracted a merely rotating movement of the drill bit interact with the material to be mined. By providing two different types of hard material or hard metal inserts on the surface of the drill bit, it is ensured that sufficient drilling progress is made available even with the rotating load or movement of the drill bit. By providing two different types of hard material or hard metal inserts, different circumstances can be taken into account in the production of a borehole with a rotating action or movement as well as with rotating and striking action or movement of a drill bit or generally a drilling tool.

To achieve sufficient drilling progress during the merely rotating stress or movement of the In addition, a drill bit is proposed that the hard material inserts interacting with the material to be mined when the drill bit rotates, as is the case with a further preferred embodiment of the drill bit according to the invention. While cutting is thus provided according to the invention in the case of the merely rotating stress, in order to achieve sufficient drilling progress in the region having greater strength or hardness, it is proposed according to a further preferred embodiment of the invention that the rotating bit and the striking movement of the drill bit with the material to be mined interacting hard material inserts are formed from essentially cylindrical hard metal pins known per se. Such hard metal pins or hard material pins are known in various embodiments, for example, possibilities for fixing them are known from AT-U 6386 mentioned at the beginning.

As already mentioned several times above, it can be assumed that if the drill bit is only subjected to rotation, sufficient drilling progress can usually only be achieved in a material which has a comparatively lower hardness or strength. Accordingly, according to a further preferred embodiment, it is provided that the hard material inserts interacting with the material to be mined during a rotating movement have a lower hardness or strength than the hard material inserts interacting with the material to be mined during rotating and striking movement. It can therefore be in

Adaptation to the material having a lower strength or hardness, for example in the entry area of a tap hole, also with a lower hardness and strength having hard material or hard metal inserts for the first part of the drilling process, so that overall less expensive elements or inserts can be provided. In addition, these elements, which have a lower strength or hardness and are used to produce the borehole with only rotating stress, are usually worn out very quickly when they enter the material which has a higher strength and which also requires a striking movement. worn out, so that the hard material inserts provided for the further drilling progress, for example formed by hard metal pins, come into engagement with the material to be mined in order to ensure the further drilling progress.

Such hard material inserts, which have a lower strength or hardness and which, as mentioned above, can be produced more cheaply, for example, are distinguished according to a further preferred embodiment in that the essentially disk-like hard material inserts interacting with the material to be mined during rotating movement two layers of different hardness are formed and are fixed, in particular welded, on a side formed in particular from weldable steel in a recess on the surface of the drill bit. Taking into account an achievable, sufficient drilling progress with only a rotating application, it is thus possible to ensure simple and inexpensive fixing in the excavation area of the drill bit by providing weldable steel on one side as an inexpensive and easy-to-machine material for the essentially disk-like excavation elements is. In order to protect the hard material inserts or dismantling elements provided for a rotating and striking stress only when the drilling operation continues, it is proposed according to a further preferred embodiment that in the direction of rotation of the drill bit a hard material insert that interacts with the material to be mined when the drill bit rotates is arranged in front of at least one hard material insert, which interacts with the material to be mined during a rotating and striking movement. The hard metal pins provided for the continuation of the bore, for example in particular cylindrical, are thus protected and protected due to the fact that they are located in the drilling shadow of the hard material elements or inserts which have a greater longitudinal extension and which are intended for the merely rotating stress , if at all, only come into contact with material that has already been mined during the first part of the borehole to be produced.

The invention is explained in more detail below with reference to exemplary embodiments schematically illustrated in the accompanying drawing. 1 shows a side view of a drill bit according to the invention for carrying out the method according to the invention; FIG. 2 shows a plan view of the drill bit according to the invention according to FIG. 1 in the direction of arrow II of FIG. 1; 3 shows a perspective view of the drill bit according to the invention on a reduced scale; and

Fig. 4 is a diagram in which the drilling progress over time or over the length of the to be produced Hole or borehole is indicated using the projection or extension according to the invention.

1 to 3, a drill bit is generally designated 1, a plurality of hard material inserts or cutting edges being provided in a surface 2 of the drill bit 1.

It can be seen in particular that essentially disk-like hard material inserts 3 are provided, each of which has an essentially equal angular distance from one another, in the illustrated embodiment of approximately 120 ° in each case, these disk-shaped hard material inserts 3 being designed, for example, in multiple layers, so that in particular a rear side 6 of the hard material cutting edges 3 provided in the direction of rotation 5 is formed from a weldable steel, whereby a simple and reliable fixing in corresponding recesses 7 of the drill bit 1 is possible.

In addition, pin-shaped or cylindrical hard-material or hard-metal inserts 8 are provided in each case in the direction of rotation 5 behind the disk-like cutting edges or hard material elements 3, two hard-metal pins 8 in the direction of rotation 5 being provided behind a cutting edge 3 in the embodiment shown in the figures. It can also be seen that the disk-like hard material inserts 3 each have a greater extension from the surface 2 of the drill bit 1 than the hard material or hard metal pins 8, as will be discussed in more detail below. In addition, in particular from FIGS. 2 and 3, passage openings 9 and 10 on the excavation surface 2 of the drill bit 1 can be seen, these serving, for example, for dispensing a flushing material and for removing the mined material.

The diagram of FIG. 4 schematically indicates the drilling progress .DELTA.l / .DELTA.t in the course of time t or in the course of length 1 of a hole to be produced, in particular a tap hole of a blast furnace. Starting from a starting time t ₀ , there is only a rotating application or movement of the drill bit 1 shown in FIGS. 1 to 3, whereby it can be seen that after a longer period or a greater length, the drilling progress is essentially constant from a time ti begins to decrease, falling below a threshold value x at a time t ₂ . If the threshold value x is undershot, which can be determined, for example, by appropriate monitoring of the drilling progress, in addition to the rotating application or movement of the drill bit 1, there is also an impacting action at time t ₂ , so that the further drilling process is carried out using rotary impact drilling is carried out. From Fig. 4 it can be seen that the drilling progress is again increased and continued at an essentially constant or only slightly decreasing level until time t ₃ of completion of the drilling, for example a tap hole of a blast furnace.

Instead of monitoring the drilling progress until the threshold value x falls below, the drilling process can be carried out, for example, in such a way that for a predetermined portion of the length of the borehole, for example at least a third, preferably approximately half, is merely a rotary movement of the drill bit, whereupon a striking movement or stress is then exerted on the drill bit 1 in order to continue the drilling sure.

Corresponding to the different loading of the drill bit 1 during the different partial areas of the borehole to be produced, it is further provided that the disk-like hard material or hard metal inserts 3 have a lower strength or hardness than the hard metal pins 8, so that from time t ₂ , wherever a striking stress is exerted on the drill bit 1, these degradation elements or hard material inserts 3, which have a lower strength or hardness, are subjected to a relatively large amount of wear and thus the hard metal pins 8 come into contact with the material to be mined in order to continue the borehole while achieving a sufficient level - Progressive drilling progress with rotary impact drilling in the period t ₂ to t ₃ .

Claims

Patent claims

1. A method for drilling a hole, in particular a tap hole of a blast furnace, with a drill bit (1), which has a plurality of hard material or hard metal inserts or cutting (3, 8) on its surface, characterized in that the drill bit (1) is driven to a rotary movement over a first partial region of the borehole to be produced, and that the drill bit (1) is driven to rotate and strike over the remaining length of the hole to be produced.

2. The method according to claim 1, characterized in that the drive with rotating movement over at least one

Third, preferably about half, the length of the borehole to be produced is made.

3. The method according to claim 1 or 2, characterized in that the drilling progress is monitored during the rotating movement and that in addition a striking movement is exerted on the drill bit (1) when a predetermined threshold value for the drilling progress is undershot.

4. Drill bit for drilling a hole, in particular a tap hole of a blast furnace, the drill bit (1) being provided with a plurality of hard material or hard metal inserts or cutting edges (3, 8), characterized in that on the extraction surface (2 ) the drill bit (1) is provided with two different types of hard material or hard metal inserts (3, 8), with a larger extension of the hard material Inserts (3) interact with the material to be mined when the drill bit (l) only rotates.

5. Drill bit according to claim 4, characterized in that the rotating material movement of the drill bit (1) with the material to be mined cooperating hard material inserts of cutting edges (3) are formed.

6. Drill bit according to claim 4 or 5, characterized in that the rotating and striking movement of the

Drill bit (1) with hard material inserts interacting with the material to be mined are formed by essentially cylindrical hard metal pins (8) known per se.

7. A core bit according to claim 4, 5 or 6, characterized in that the hard material inserts (3) interacting with the material to be mined during rotary movement and a hard material insert (8) with respect to the hard material inserts (8) interacting during rotary and striking movement with the material to be mined exhibit.

8. Drill bit according to one of claims 4 to 7, characterized in that the substantially disc-like hard material inserts (3) interacting with the material to be mined when rotating are formed from two layers of different hardness and on a side made in particular of weldable steel are fixed, in particular welded, in each case in a recess (7) on the extraction surface (2) of the drill bit (1).

9. Drill bit according to one of claims 4 to 8, characterized in that in the direction of rotation (5) of the drill bit (1) each with a rotating movement of the drill bit (1) interacting with the material to be mined hard material insert (3) before at least one hard material insert (8 ) is arranged, which interacts with the material to be mined during rotating and striking movement.