JP7606826B2 - Hole Drill Bit - Google Patents

Description

The present invention relates to a tap hole bit that uses a tap hole opening machine to open holes in the mud filled in the tap hole of a blast furnace and allow pig iron to flow out.

In blast furnaces that produce pig iron, it is generally necessary to open the tap hole located at the bottom of the furnace in order to tap off the molten iron that has been melted at high temperatures from the iron ore. This is because the tap hole is filled with unshaped refractory material (mud) and sealed when the molten iron is not being discharged. To open the tap hole, a tap hole bit is fixed to the end of a pipe rod and attached to a tap hole opening machine, which then opens the hole by rotating or striking it. Various shapes of tap holes are used for this tap hole opening operation.

In the past, drilling operations required time to decide where to drill holes, and because the drilling position could not be decided, the drilling bit would swing on the mud surface, which could lead to problems such as broken rods and damage to the tapping mud surface. In addition, hard foreign matter such as ingots (such as solidified hot liquid pig iron from the blast furnace that has cooled) mixed in with the tapping mud could increase drilling time (or be interrupted in some situations) or cause rapid wear on the drilling bit.

For this reason, in the past, a two-stage method was sometimes used in which a certain distance was drilled in advance with the tip of a rod attached to the tap hole drilling machine, and then the rod was withdrawn, a drilling bit was attached, and the filling mud was drilled again. However, because the drilling work is done in two stages, not only is the work complicated and does not improve productivity, but it is also dangerous work, making it unfavorable in terms of the working environment. Furthermore, if the drilling work cannot be done due to the presence of hard foreign matter such as ingots, the work must be stopped temporarily and the ingots must be removed.

To make the hole drilling method possible in a single step, a method is known in which high-pressure water is passed through the inside of the rod and hole drilling bit to cool them, and water (including liquid, mist, etc., the same applies below) is sprayed from the tip of the bit to remove the grinding debris (for example, Patent Document 1).

A drilling bit that allows tap hole filling mud to be drilled in one step is also known (see, for example, Patent Document 2). This drilling bit is advantageous in that it can be propelled through the filling mud along its central axis without the risk of the bit itself vibrating, and the filling mud can be drilled immediately.

Japanese Patent Application Publication No. 9-13113 JP 2006-307258 A

However, in the method described in Patent Document 1, the hole is drilled in one step while the rod, drilling bit, and filling mud are cooled, so it is difficult to prevent vibration caused by rotational vibration around the center line of the drilling bit, and it is difficult to perform smooth and proper one-shot drilling along the hole center line.

In addition, in the method described in Patent Document 2, after the mud hole opening position is determined and the hole opening begins, the mud is cut further with the flat surface of the bit, so it can take some time to open the hole, and there is room for improvement to open the hole in a shorter time.

Furthermore, the technology disclosed above does not take into consideration measures against hard foreign matter such as ingots (such as solidified pig iron that has cooled from high-temperature liquid pig iron from a blast furnace) that may be mixed in with the tapping mud. When ingots are formed in the tapping mud, if a conventional drilling bit is used, the drilling operation must be temporarily stopped, the drilling bit in operation must be temporarily removed, and the ingots must be removed using a rod for removing the ingots, or the like, which significantly lengthens the operation time, which is an issue that remains.

The main objective of the present invention is to open the tap hole filling mud in one step and improve the straightness and drillability during opening. In addition, even if there is hard foreign matter such as ingots (such as solidified hot liquid pig iron from a blast furnace that has cooled) mixed in the tap hole mud, the hole can be opened by normal operations without the need to remove the ingots. Furthermore, this leads to improved productivity and cost reduction.

The present invention relates to the following (1) to (7).
(1) A hole-drilling bit for a tap hole of a blast furnace, which has a base metal formed with a swarf discharge groove, a protruding end surface, a blade portion, and an outlet, the hole-drilling bit having a roughly conical crushing portion, at least one of the blade portions being provided on a roughly conical inclined surface of the crushing portion, a hollow portion being formed inside the hole-drilling bit, at least one of the swarf discharge grooves being formed on the outer periphery of the hole-drilling bit, the protruding end surface being formed between adjacent swarf discharge grooves, and at least one of the outlet holes being formed on the conical inclined surface of the hole-drilling bit and on the surface of the swarf discharge groove.
(2) A hole-drilling bit for a tap hole of a blast furnace as described in (1) above, characterized in that a blade portion mounting groove is provided in the base metal, and the blade portion is fixed to the blade portion mounting groove.
(3) A hole-drilling bit for a tap hole of a blast furnace according to (1) or (2), characterized in that at least three or more blade portions are formed.
(4) A tap hole drilling bit according to any one of (1) to (3), characterized in that the blade portion is formed from two or more blade portion forming members.
(5) A tap hole drilling bit as described in (4) above, characterized in that one side of the blade portion forming member is approximately triangular and the other side is approximately trapezoidal.
(6) The tap hole drilling bit according to any one of (1) to (5), characterized in that the tip end of the tap hole drilling bit comprises a crushing portion and the rear end of the tap hole drilling bit comprises a rod fixing portion.
(7) A blast furnace tap hole opening machine, in which the tap hole opening bit for a blast furnace according to any one of (1) to (6) and the hollow rod are screwed together while sharing a central axis.

According to the hole-drilling bit of the present invention, it is possible to drill the taphole filling mud in one step and improve the straightness and excavation during drilling. Furthermore, even if there is a hard foreign object such as a bare metal formed in the tapping mud, it is possible to drill the hole while avoiding the bare metal in the normal drilling process without performing a separate operation to remove the bare metal, thereby improving the work efficiency. Furthermore, compared with the conventional hole-drilling bit using a button-shaped carbide tip, even if such a metallic bare metal is present, the hole-drilling bit having a blade portion can cut the bare metal as if cutting a metal with a blade.

1A and 1B are a plan view and a front view, respectively, of a hole-drilling bit according to an embodiment of the present invention. 1 shows a cross-sectional view of a hole drilling bit according to an embodiment of the present invention. 1A and 1B are a plan view and a front view, respectively, of a hole-drilling bit according to an embodiment of the present invention before a blade portion is attached thereto. 1 is a cross-sectional view of a hole-drilling bit according to an embodiment of the present invention before a blade portion is attached. 1 shows a state in which a hole drilling bit according to an embodiment of the present invention is attached to a rod. FIG. 1 is a schematic diagram showing a state in which matte filled in a tap hole is drilled using a drilling bit according to an embodiment of the present invention. FIG. 1 is a schematic diagram showing a state in which a hole-drilling bit according to an embodiment of the present invention drills a filler mud on which a bare metal has been formed. 1 shows the state of drilling operation when a base metal is formed inside the filling mud in the drilling bit of this embodiment and a conventional drilling bit. FIG. 1 is a diagram illustrating the rake angle α, the blade angle β, and the clearance angle γ in the shape of a blade. . (a) First blade portion forming member 2' and (b) second blade portion forming member 2' according to an embodiment of the present invention 13 is a view showing a blade portion forming member of FIG.

The following describes an embodiment of the present invention with reference to the drawings. Figure 1(a) shows a plan view of the hole-drilling bit 1 of this embodiment, and Figure 1(b) shows a front view of the hole-drilling bit 1 of this embodiment. In Figure 1, 2 indicates a blade portion that cuts the filling mat, 3 indicates an outlet for air or water, etc., 4 indicates a cuttings discharge groove for discharging cuttings generated by excavating the filling mat, 5 indicates a rod attachment portion for attaching a rod, and 6 indicates a protruding end face.

The blade portion 2 in this embodiment is formed by combining blade portion forming members of two different shapes. The first blade portion forming member 2' formed at the tip end of the hole-drilling bit 1 is approximately triangular in shape as shown in the cross section in Figures 2 and 10, and the second blade portion forming member 2'' formed at the rear end of the hole-drilling bit 1 is approximately trapezoidal in shape as shown in the cross section in Figures 2 and 10. In addition, the rod attachment portion 5 shares the central axis of the hole-drilling bit 1 (although it is not necessary for them to share the same central axis strictly speaking). The rod attachment portion 5 in this embodiment is formed in a cylindrical shape.

The hole-drilling bit 1 of this embodiment has a crushing section 10 in a substantially conical shape formed on the upper end side, and a rod attachment section 5 formed on the rear end side. In this embodiment, the crushing section 10 and the rod attachment section 5 are formed by cutting out the same base metal. In addition, when the crushing section 10 is in a state where the blade section 2 is not provided on the base metal, the tip of the substantially conical shape is shaped to have a surface that is substantially parallel to the rear end of the rod fixing section 5 when viewed from the front (FIG. 3(a)). Furthermore, in this embodiment, one nozzle 3 is provided between the blade sections 2 on the inclined surface of the crushing section 10, and one nozzle 3 is also provided in the cuttings discharge groove section 4 between the protruding end faces 6 of the nozzles 3. According to this embodiment, three blade sections 2 are used to perform the hole-drilling work, which enables smooth rotary cutting, and the nozzle 3 can be simply formed in the above-mentioned location to discharge the crushed chips to the outside.

In this embodiment, blade attachment grooves 8 for installing three blades 2 are formed on the generally conical inclined surface of the crushing section 10. The blade attachment grooves 8 are formed in three equal parts on the inclined surface of the hole-drilling bit 1 so as to be generally even when the hole-drilling bit 1 is viewed from the tip (see the front views of Figs. 1(a) and 3(a)). (For example, in this embodiment, the grooves are divided into three parts, but they may be divided into two, four, five or more parts, or may not be divided into equal parts.)
The blade attachment groove 8 is a flat surface when viewed from the front of the approximately conical tip of the crushing section 10 of the hole-drilling bit 1. This is because, as shown in Figures 1 to 4, the structure is for forming two blade shapes in the crushing section. A second blade attachment groove is formed in a shape that is approximately parallel to the slope of the approximately conical shape from a point slightly above the center of the approximately conical shape toward the rear end side of the crushing section 10. Furthermore, a first blade attachment groove is formed in an approximately L-shape from the end on the tip side of the second blade attachment groove, with one side of the L-shape being approximately parallel to the rear end surface of the rod fixing section 5 of the hole-drilling bit. With these structures, it is possible to insert and fix an approximately triangular blade part into the approximately L-shaped first blade attachment groove, and further it is possible to insert and attach the blade part so as to follow the second blade attachment groove formed on the slope of the crushing section. With such a structure for mounting the blade portion, when performing the hole opening work, it is possible to receive the force of impact and rotation on one side of the approximately L-shaped first blade portion mounting groove (the side that is approximately parallel to the rear end surface of the rod fixing portion 5), making it possible to crush with a stronger force, and it is possible to reduce the frequency of replacing the blade portion 2. Since the blade portion 2 is formed at the tip, it is a member that directly receives the impact force. In order to make the structure such that the base metal is easily subjected to the impact force, a parallel surface is provided. In addition, since the cutting edge is a member that receives the impact force, there is a possibility that damage such as cracking and chipping may occur. In this respect, compared to the case where a blade portion of a one-piece type is used, damage to the entire blade portion can be suppressed, and the crushing ability can be improved. As a result, it is more preferable to use the blade portion 2 divided into two so that the damaged part is minimized even if the blade portion is damaged.

When viewed from above (FIGS. 1(a) and 3(a)), the hole-opening bit 1 has a shape in which the outer circumference of the hole-opening bit 1 is divided into several parts (for example, in this embodiment, it is divided into three equal parts, but it may be divided into two, four, five or more equal parts, or it may not be divided equally), and the outer circumference of the crushing section 10 is cut out from the middle to the lower end to provide a cuttings discharge groove section 4. That is, on the outer circumference of the crushing section 10 of the hole-opening bit 1, the cuttings discharge groove section 4 (three in total) and the protruding end faces 6 (three in total) formed between adjacent cuttings discharge groove sections 4, 4 are formed, and the number of cuttings discharge groove sections is the same as that of the cuttings discharge groove sections. In this embodiment, the number of cuttings discharge groove sections 4 and the protruding end faces 6 are three each, and as a result, the cuttings discharge groove section is recessed toward the center when viewed from above of the hole-opening bit body 1. Therefore, in this embodiment, the chip discharge groove portion has a shape that is cut out in a roughly arc shape when viewed in plan view, as shown in Figures 1(a) and 3(a).

Figure 2 shows a cross-sectional view of the hole-drilling bit 1 of this embodiment. The hole-drilling bit 1 of this embodiment has a hollow portion 7, which is connected to the path of the air and water outlet 3 shown in Figure 1. With this structure, the filling mat, bits, chip chips, etc. generated during the hole-drilling operation are discharged from the opening of the filling mat 40 through the cuttings discharge groove portion 4 to the outside of the tap hole, while the filling mat of the tap hole 30 is opened to tap the iron.

Figure 3 shows the state of the hole-drilling bit 1 of this embodiment before the blade portion is attached ((a): plan view, (b): front view), and Figure 4 shows a cross-sectional view of the hole-drilling bit 1 of this embodiment before the blade portion is attached. Here, 8 is a blade portion attachment groove, and in this embodiment, the blade portion 2 is inserted into the blade attachment groove 8 and fixed to form the blade portion on the base metal.

Three blade portions 2 are formed on the hole-drilling bit 1 of this embodiment. The material of the blade portion is not particularly limited, and the same material as the base metal, such as iron or steel, may be used. For example, alloy steel (high chromium steel, high manganese steel) or cast steel (high chromium cast steel, high manganese cast steel) containing a large amount of chromium or manganese, or alloy steel or cast steel containing hard particles (super-hard particles or cermet particles) can be used as the material of the blade portion 2. In order to perform hole drilling more efficiently, it is preferable to use a super-hard alloy obtained by mixing and sintering tungsten carbide and cobalt, or a material to which titanium carbide, tantalum carbide, or the like is added. Generally, the shape of a blade has a rake angle α and a clearance angle γ as shown in FIG. 9. The rake angle is an angle that serves to scoop up chips generated on the front side in the tool travel direction, and the clearance angle is an angle set so as not to interfere with the workpiece. The tip angle of the blade is called the blade angle β, and it is common to use a larger blade angle for hard workpieces and a smaller blade angle for soft workpieces. The strength of the blade tip decreases as the clearance angle γ increases, so it is desirable to use a clearance angle of about 0 to 15°, and a clearance angle of 10° was used in the hole-drilling bit of this embodiment (see γ in Figure 2). In addition, as the clearance angle β decreases, the strength of the blade decreases and it becomes more likely to chip, so the preferred range for the blade angle β is 60 to 100° (80° was used in this embodiment), and the rake angle α should also be as small as possible, preferably around -15 to 15° (there may be negative rake angles), and a clearance angle of 0° was used in the hole-drilling bit of this embodiment.

When viewed from the front as shown in FIG. 1(b), the blade sections 2 used in the hole-drilling bit 1 of this embodiment have a shape in which one end of the three blade sections 2 come together at a generally conical tip, forming the tip of the hole-drilling bit 1. As a result, when viewed from the front as shown in FIG. 1(b), the shape of the crushing section 10 with the blade sections 2 attached is also generally conical, with no flat tip surface.

In this embodiment, the blade portion 2 is inserted into the blade mounting groove portion 8 and fixed by brazing using brass brazing. In this embodiment, the brazing material used for fastening is brass brazing, but this is not limited to this, and other brazing materials, such as silver brazing, may be used, and the blade portion 2 can also be attached by welding or other methods.

Figure 5 shows the hole-drilling bit 1 of this embodiment attached to a hollow rod 20. The hole-drilling bit 1 of this embodiment is connected to a general hollow rod 20 used to drill holes in mud filled in the tap hole of a blast furnace. The method of attaching the hole-drilling bit and the hollow rod is not particularly limited, and the rod mounting part 5 can be protruded from the rear end surface (bottom surface) of the hole-drilling bit 1 and welded to the tip surface of the rod, or a female thread can be formed inside the rod mounting part 5 and screwed to a male thread provided at the tip of the hollow rod to connect, or a male thread can be formed on the outer surface of the rod mounting part 5 and screwed to a female thread provided in a concave shape at the tip of the hollow rod to connect. In this embodiment, a female thread is formed inside the rod mounting part 5 and screwed to a male thread provided at the tip of the hollow rod to connect.

Figure 6 shows a schematic diagram of the state in which the hole-opening bit 1 of this embodiment is attached to a rod 20 to open the mud filled in the taphole. The other end of the rod 20 opposite to the end to which the hole-opening bit 1 is attached is connected to a taphole opening machine (not shown). The hollow rod 20 and the hole-opening bit 1 supported by the taphole opening machine are rotated and advanced along the centerline of the taphole of the blast furnace, and the striking force of the taphole opening machine is applied to the hole-opening bit through the rod, so that the tip where one end of the blade portion 2 provided on the sloping surface of the hole-opening bit 1 meets is propelled along the centerline into the mud filled in the taphole. At this time, since the tip of the drill bit 1 has a tip where one end of the blade part is gathered, the tip is within the center line, and the conical shape of the drill bit 1 presses the filling mud while rotating, and the blade part 2 is formed on the slope surface of the drill bit 1 from the tip, so that it advances in the direction of the center line by striking force and rotational force without deviating from the center line. At the same time, the blade part 2 formed on the slope surface of the drill bit 1 strikes and rotates to crush the filling mud, and the crushed chips are discharged from the cuttings discharge groove to the outside of the tap hole by air or water jetted at high pressure from the nozzle 3, and the tap hole is opened in the direction of the center line in one step operation. The hollow rod 20 used in this embodiment has a length of about 6 to 6.5 m and an outer diameter of φ34 to 42.7 mm, and the rear end face of the drill bit 1, which shares the central axis, is connected to the tip of the rod 20.

Figure 7 shows the state of drilling work when ingots have formed inside the packed mud. When drilling the tap hole, cracks may appear in the drilled wall of the packed mud during drilling work, or side holes may form in the part of the packed mud pushed into the furnace (Figures 7(a) and (b)). One of the reasons for the formation of ingots is thought to be that when the molten iron in the furnace is subsequently tapped, the molten iron remains in the cracks or side holes and cools and solidifies, forming ingots inside the packed mud (Figures 7(c) and (d)). It is not desirable to perform the next drilling work when ingots remain, as this will cause inconvenience as mentioned above.

Figure 8(a) shows the hole opening state using a conventional drilling bit, and Figure 8(b) shows the hole opening state using the drilling bit 1 of this embodiment. With a conventional drilling bit, when it hits the bare metal, the bare metal is not crushed by the impact force of the protrusions, but is scraped away by the rotational force. In the part where there is no bare metal, the protrusions crush the filling mud, so it bends around the bare metal. (Figure 8(a)). In contrast, when the drilling bit 1 of this embodiment is used, after the tip of the drilling bit 1 (the part where one end of the blade part 2 gathers) hits the bare metal, the blade bites into it due to the impact force, and the bare metal is scraped away by the rotation, and it is possible to continue straight ahead to remove the bare metal. In the case of conventional drilling bits, the tips of the tips installed on the drilling surface and the inclined drilling surface are arranged on almost the same plane, so if metallic material such as raw metal is present within the gauge diameter of the drilling bit, the drilling performance will be poor, and the bit will avoid the raw metal without being able to crush it (curved drilling), or the carbide tip will come into contact with the raw metal, causing severe wear and causing significant cracking and chipping, making it impossible to drill. If the drilling is performed in a curved manner, the drilling diameter will increase locally, and in the worst case, the furnace wall may be damaged. In order to minimize the amount of mud material filled, it is ideal to finish drilling at the same diameter, and in order to avoid damaging the hole wall, it is necessary to use the drilling bit of this embodiment to drill in a straight line.

By using the hole-drilling bit 1 of this embodiment, the tip of the hole-drilling bit is sharp, so it is easy to position the bit so that it can enter the filling mud, and hole-drilling can be started, and it is excellent in that it can improve the straightness and excavation during hole-drilling. In addition, since a blade portion is provided on the slope surface of the approximately conical hole-drilling bit, even if there is a hard foreign object such as ingot (such as solidified hot liquid pig iron from a blast furnace that has been cooled) mixed in the pig iron mud, the hole-drilling work can be continued as is. This prevents the hole-drilling time from increasing (or being interrupted depending on the situation) and the hole-drilling bit from wearing out rapidly, and is excellent in terms of work efficiency and economy.

<Other form examples>
(1) In this embodiment, the blade portion is formed separately and inserted into the blade mounting groove. However, the present invention is not limited to this. The blade portion may be formed by integral molding with the base metal.
(2) In the present embodiment, a combination of two shapes of blade portion-forming members is used as the blade portion 2, but this is not particularly limited to the above. The blade portion 2 may be integrally molded alone, or two or more blade portion-forming members may be used, or two or more shapes of blade portion-forming members may be used.
(3) In this embodiment, the crushing portion 10 is formed so that the tip is flat when it is formed from the base metal, but this is not limited to this. It may be formed into an approximately conical shape from the base metal state, or a blade portion mounting groove may be formed on the sloping surface and the blade portion may be inserted into the groove.
(4) In this embodiment, the chip discharge groove portion is cut out in a substantially arc shape. However, it may be cut in a substantially V shape.
The cutout shape may be substantially triangular, substantially concave, or the like.
(5) In this embodiment, the hole-drilling bit 1 is provided with three blade portions 2, but this is not particularly limited, and the hole-drilling bit 1 may be used with fewer or more than three blade portions as long as the effects of the present invention can be obtained.

Reference Signs List 1: Hole-drilling bit 2: Blade portion 2': First blade portion forming member 2'': Second blade portion forming member 3: Jet port 4: Cuttings discharge groove 5: Rod mounting portion 6: Projecting end surface 7: Hollow portion 8: Blade portion mounting groove portion 10: Crushing portion 20: Hollow rod 30: Tap hole 40: Filling mud 50: Base metal 70: Crack 80: Horizontal hole

Claims (7)

A bit for drilling a tap hole of a blast furnace, which forms a chip discharge groove, a protruding end face, a blade portion, and a nozzle on a base metal,
The hole-drilling bit has a substantially conical crushing portion,
At least three or more of the blade portions are provided on a substantially conical inclined surface of the crushing portion,
The blade portion is formed on the slope of the hole drilling bit so that the blade portion is approximately uniform when viewed from the tip end of the hole drilling bit, and
A hollow portion is formed inside the hole-drilling bit,
At least one cutting chip discharge groove is formed on the outer periphery of the hole-opening bit,
The protruding end surfaces are formed between the adjacent cuttings discharge grooves,
At least one of the nozzles is formed on the cone-shaped inclined surface of the hole-opening bit and on the surface of the cuttings discharge groove.
A tap hole drilling bit for a blast furnace, comprising: A bit for drilling a tap hole of a blast furnace, which forms a chip discharge groove, a protruding end face, a blade portion, and a nozzle on a base metal,
The hole-drilling bit has a substantially conical crushing portion,
At least one blade portion is provided on a substantially conical inclined surface of the crushing portion,
The blade has a clearance angle γ of 0 to 15°, a cutting edge angle β of 60 to 100°, and a rake angle α of -1
Form it so that it becomes 5 to 15 degrees,
A hollow portion is formed inside the hole-drilling bit,
At least one cutting chip discharge groove is formed on the outer periphery of the hole-opening bit,
The protruding end surfaces are formed between the adjacent cuttings discharge grooves,
At least one of the nozzles is formed on the cone-shaped inclined surface of the hole-opening bit and on the surface of the cuttings discharge groove.
A tap hole drilling bit for a blast furnace, comprising: A bit for drilling a tap hole of a blast furnace, which forms a chip discharge groove, a protruding end face, a blade portion, and a nozzle on a base metal,
The drilling bit has a crushing section at the front end and a rod fixing section at the rear end.
The hole-drilling bit has a substantially conical crushing portion,
At least one blade portion is provided on a substantially conical inclined surface of the crushing portion,
the blade portion is formed from two or more blade portion forming members including a first substantially triangular blade portion forming member and a second substantially trapezoidal blade portion forming member;
A blade portion attachment groove is provided on the base metal, and the blade portion is fixed to the blade portion attachment groove;
a second generally trapezoidal blade portion attachment groove formed from a position slightly above the center of the generally conical hole-drilling bit toward a rear end side in a shape generally parallel to the generally conical slope;
a first substantially triangular blade portion attachment groove is formed in a substantially L-shape from a tip end of the second substantially trapezoidal blade portion attachment groove such that one side of the L-shape is substantially parallel to a rear end surface of the rod fixing portion of the hole-drilling bit;
A hollow portion is formed inside the hole-drilling bit,
At least one cutting chip discharge groove is formed on the outer periphery of the hole-opening bit,
The protruding end surfaces are formed between the adjacent cuttings discharge grooves,
At least one of the nozzles is formed on the cone-shaped inclined surface of the hole-opening bit and on the surface of the cuttings discharge groove.
A tap hole drilling bit for a blast furnace, comprising: The tap hole drilling bit for a blast furnace according to claim 1 or 2, characterized in that a blade attachment groove is provided on the base metal, and the blade is fixed to the blade attachment groove. 4. The tap hole drilling bit according to claim 3 , wherein one side of the blade portion forming member is substantially triangular and the other side is substantially trapezoidal. The tap hole drilling bit according to claim 1 or 2, characterized in that the tip side of the drilling bit consists of a crushing part and the rear end side of the drilling bit consists of a rod fixing part. 4. A blast furnace tap hole opening machine, comprising: a tap hole opening bit for a blast furnace according to any one of claims 1 to 3 ; and a hollow rod connected to the tap hole opening bit, the hollow rod being screwed together so as to share a central axis.

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