JP2004084009A - Boring bit for tapping - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boring bit for tapping, which can smoothly discharge cuttings from a digging part. <P>SOLUTION: The boring bit 1 for tapping, comprising the main body 2 of the bit attached at a tip of a rotatable rod, a tip 3 made of a hard metal and implanted in the main body 2, a guide member 4 installed upright at the center in the tip of the main body 2, and a hole 6 for purging air installed on the apical surface 5 of the main body 2, has a channel 11 formed on the outer peripheral surface 9 of the main body 2, wherein the channel 11 tilts from the tip surface 5 of the main body 2 toward the proximal end surface and the rear of a rotating direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tapping counterbore bit which is a drilling tool used for repairing a taphole of a blast furnace or the like.
[0002]
[Prior art]
Generally, tapping in a blast furnace is performed by drilling a mud blocking the taphole with a taphole rock drill, forming an opening with a smaller diameter than the taphole, and flowing molten iron through the opening. When a predetermined amount of hot metal flows out, the opening is closed with a mud and tapping is completed. By repeatedly performing such tapping, the mud deteriorates due to the erosion action of the hot metal or slag, gas in the blast furnace leaks to the outside, or mud leakage occurs when the tap hole is closed, resulting in blockage. It may be impossible.
[0003]
Therefore, it is necessary to remove the degraded mud itself at an appropriate interval and repair it with a new mud. The work for removing old mud was performed by attaching a tapping bit drill with a diameter almost the same as the inside diameter of the tap hole to a tap hole drilling machine, and excavating the mud with the tapping bit. The tapping bit for tapping is a drilling tool that pulverizes the mud with a cemented carbide chip implanted at the tip end face and pushes the pulverized cutting powder by air blow from an air purge hole provided at the tip end face.
[0004]
[Problems to be solved by the invention]
By the way, the drilling diameter of the above-mentioned tapping bit for the tapping is larger than the diameter of the opening used for tapping, and the drilling area is large, so that a large amount of drilling mud dust is generated, and the discharge of the drilling powder is smoothly performed. There was a problem that was not done. That is, even if the dust is swept away by the air blow, the dust is not efficiently discharged, and the dust accumulates between the tip end surface of the tapping bit and the excavated surface. As described above, since the not-exhausted cutting powder accumulates at the excavated portion, not only does the excavation speed decrease, but also there is a problem that so-called secondary abrasion occurs in which chip wear is accelerated by the cutting powder.
[0005]
The present invention has been made in view of such a background, and an object of the present invention is to provide a tapping counterbore bit capable of smoothly discharging a dust from an excavation site.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention proposes the following means.
The tapping bit for tapping of the present invention comprises a bit body attached to the tip of a rotatable rod, a cemented carbide tip implanted in the bit body, and a guide erected at the center of the tip of the bit body. It is a tapping counterbore bit having a member and an air purge hole provided on a tip end surface of the bit main body, wherein a groove is formed on an outer peripheral surface of the bit main body, and the groove is formed on a tip end surface of the bit main body. , And is inclined rearward in the rotational direction from the base end face toward the base end face.
[0007]
According to the counterbore bit for tapping according to the present invention, since the groove is inclined rearward in the rotational direction from the distal end surface to the base end surface of the bit main body, the dust is guided by the inclination of the groove and the bit body is inclined. To the base end side of In other words, the boring powder excavated by the rotation of the tapping bit for tapping enters the groove, and is forcibly pushed out to the base end face side by its inclination. As a result, the discharging property of the dust is improved, and the excavation can be performed well without lowering the excavation speed. In addition, it is possible to prevent secondary wear of the chip due to the cutting powder.
[0008]
In addition, the tapping bit for tapping of the present invention, in the tapping bit for tapping, with respect to the radial arrangement of the air purge hole, with respect to the dimension from the air purge hole to the side surface of the guide member, The air purge hole is provided at a position where the ratio of the dimension to the outer peripheral surface of the bit main body is 3.5 to 4.5.
[0009]
According to the counterbore bit for tapping according to the present invention, the ratio of the dimension from the air purge hole to the outer peripheral surface of the bit main body with respect to the dimension from the air purge hole to the side surface of the guide member is arranged in the radial direction of the air purge hole. Since the air purge holes are provided at positions from 3.5 to 4.5, the dust is efficiently discharged by air blowing from the air purge holes. In other words, if the air purge hole is arranged radially outward from the above-described position, the cutting powder accumulates on the center side of the tip end surface of the tapping counterbore bit. Although the momentum of the air blow is weakened at the peripheral edge, by arranging it at the above-described position, the dust can be efficiently discharged by the air blow. Thereby, it is possible to excavate satisfactorily without the cuttings accumulating on the tip end surface.
[0010]
Further, the tapping counterbore bit of the present invention, in the tapping counterbore bit, with respect to the rotation direction arrangement of the air purge hole, with respect to the angle from the air purge hole to the center of the groove in the rotation direction forward direction, The air purge hole is provided at a position where the ratio of the angle to the center of the groove in the backward direction in the rotation direction is 1 to 2.8.
[0011]
According to the counterbore bit for tapping according to the present invention, the arrangement of the air purge hole in the rotation direction is relative to the angle from the air purge hole to the center of the groove in the rotation direction in the rotation direction, and the groove in the rear direction in the rotation direction. Since the air purge hole is provided at a position where the ratio of the angle to the center is 1 to 2.8, the dust is efficiently discharged by air blowing from the air purge hole. In other words, if the air purge hole is disposed rearward in the rotational direction from the above-described position, the dust accumulates in the forward direction in the rotational direction from the air purge hole, and if the air purge hole is disposed in the forward direction, the dust in the rotational direction Although the force of the air blow is weakened in the vicinity of the groove in the rearward direction, by arranging it at the above-described position, the dust can be efficiently discharged by the air blow. Thereby, it is possible to excavate satisfactorily without the cuttings accumulating on the tip end surface.
[0012]
Further, in the tapping counterbore bit of the present invention, in the tapping counterbore bit, the bit body is formed such that a pin hole into which a fixing pin for fixing the guide member is inserted extends in the rotation direction. The pin hole is provided with a step portion having a smaller inner diameter at the rear side in the rotation direction.
[0013]
According to the counterbore bit for tapping according to the present invention, a pin hole in which a fixing pin for fixing the guide member is inserted is formed in the bit body so as to extend in the rotation direction, and the pin hole has Since a step portion having a smaller inner diameter is provided at the rear in the rotation direction, the rotation during the excavation work applies a force in a direction in which the fixing pin is pressed against the step portion. Thus, the fixing pin is prevented from falling off, and the guide member can be securely fixed to the bit body.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the counterbore bit 1 for tapping includes a bit body 2 formed in a substantially disk shape, a cemented carbide chip 3 implanted in the bit body 2, and a tip of the bit body 2. It is provided with a guide member 4 erected in the center of the surface 5 and an air purge hole 6 provided in the tip end surface 5 of the bit body 2. At the base end of the bit main body 2, a rod mounting portion 7 for mounting a rod for transmitting rotational power is provided, and in the center of the distal end surface 5 of the bit main body 2, a guide member mounting portion 8 for mounting the guide member 4 is provided. Have been. In the figure, the direction of rotation during excavation is the direction of arrow R.
[0015]
Also, four grooves 10 are formed on the tip end surface 5 of the bit main body 2 at regular intervals toward the outer periphery, and four grooves 11 are formed on the outer peripheral surface 9 of the bit main body 2 so as to communicate with the grooves 10. Is formed. The groove portion 11 is formed so as to be inclined rearward in the rotational direction from the distal end surface 5 of the bit main body 2 toward the proximal end surface 12. That is, as shown in FIG. 2, the central axis C of the groove 11 is formed so as to be inclined with respect to the rotation axis O of the counterbore bit 1 for tapping. At this time, the inclination angle of the center axis C with respect to the rotation axis O is about 25 °. As described above, the groove 11 is formed to be inclined, and the side surface 11 a on the rear side in the rotation direction of the groove 11 is formed to face the base end surface 12 of the bit body 2.
[0016]
The air purge holes 6 are jet ports for jetting an air blow for flushing out the dust, and are equally spaced circumferentially at four locations on the tip end surface 5 of the bit body 2 and have the same distance from the rotation axis O. Are arranged like a ring. As shown in FIG. 1, the position of the air purge hole 6 in the radial direction is determined by the size of the air purge hole 6 from the dimension a to the side surface 4 a of the guide member 4 inward in the radial direction. The dimension b from the hole 6 to the outer peripheral surface of the bit main body 2 in the radially outward direction is set to a ratio of 3.5 to 4.5 times. Further, the position of the air purge hole 6 in the rotation direction is determined by the angle α from the air purge hole 6 to the center axis C of the groove 11 in the forward direction of the rotation direction from the air purge hole 6 to the rotation direction. The angle β to the central axis C of the groove 11 in the rearward direction is set to a ratio of 1 to 2.8 times.
[0017]
The guide member mounting portion 8 includes a projecting portion 13 provided at the center of the distal end face 5 of the bit body 2, a mounting hole 13 a provided inside the projecting portion 13 along the rotation axis O, and a base of the mounting hole 13 a. It is formed to have a female screw portion 14 provided on the end side and a pin hole 15 provided to be opened on the side surface of the protruding portion 13. FIG. 3 shows a cross-sectional view (a cross-sectional view taken along the line AA in FIG. 2) in a plane passing through the central axis of the fixing pin 18. At the time of excavation, the tapping bit 1 for tapping rotates in the direction of arrow R in the figure. The pin holes 15 extend in the tangential direction of a circle formed by the inner peripheral surface of the mounting hole 13a, and are provided at two places so as to be parallel to each other with the rotation axis O therebetween. The portion beyond the point of contact is defined as a large-diameter portion, and beyond this is defined as a small-diameter portion via a step portion 19 that reduces the diameter by one step. As shown in the figure, the step portion 19 is provided rearward in the rotation direction. The large diameter portion is opened forward in the rotation direction on the side surface of the protrusion 13, and the small diameter portion is opened rearward in the rotation direction. At the contact point with the circle formed by the mounting hole 13a, a substantially semicircular portion on the rotation axis O side of the circle formed by the cross section of the pin hole 15 overlapping the mounting hole 13a is formed on the inner peripheral surface of the mounting hole 13a. It is made to open.
[0018]
The guide member 4 is a substantially rod-shaped member having substantially the same diameter as the opening formed in the mud. The guide member 4 has a male screw portion 16 screwed into the female screw portion 14 at the base end thereof, and a shaft corresponding to the pin hole 15. A pair of groove-shaped engaging portions 17a having a semicircular cross section having substantially the same diameter as the pin hole 15 are provided on the outer peripheral portion of the portion 17 in a tangential direction of a circle formed by the outer periphery of the shaft portion 17 in a cross section orthogonal to the rotation axis O. Are formed in parallel on opposite sides of the rotation axis O. The guide member 4 is fixed with a fixing pin 18 in a state where the male screw portion 16 is screwed into the female screw portion 14 of the guide member mounting portion 8 and the engaging portion 17a is fitted to the portion of the pin hole 15 opened to the mounting hole 13a. Is inserted and fixed. The fixing pin 18 is inserted from the front in the rotation direction of the pin hole 15, and the entire fixing pin 18 enters the pin hole 15 in a state where the distal end surface 18 a of the fixing pin 18 is in contact with the step 19. With the guide member 4 fixed in this way, a space 14a is formed at the bottom of the female screw portion 14, the air purge hole 6 communicates with the space 14a, and the space 14a It is also connected to the bottom.
[0019]
When the above-described tapping bit 1 for tapping is used for repairing a tapping hole, as shown in FIG. 4, it is used by being attached to a drilling machine 20 which is a taphole drilling machine. The drill 20 is provided in the extension direction of the tap hole 22 formed in the refractory brick 21 of the blast furnace, and the drive shaft of the drill 20 and the central axis of the tap hole 22 are coaxial. Fixed. A rod 25 is attached to the drilling machine 20 via a tapping socket 26 and an adapter 27, and a tapping bit 1 for tapping is attached to a tip of the rod 25. The tapping socket 26, the adapter 27, and the rod 25 are formed in a hollow shape, and can supply the compressed air supplied from the drilling machine 20 to the tapping bit 1 for tapping. The air is blown out from the inner peripheral bottom surface as an air blow through the air purge hole 6 through the space 14 a at the bottom of the female screw portion 14 of the guide member mounting portion 8.
[0020]
An opening 24 for tapping is formed in the mud 23 that closes the taphole 22, and excavation is performed in a state where the guide member 4 of the tapping bit 1 for tapping is inserted into the opening 24. The tapping counterbore 1 stably moves straight by the guide member 4. For example, the tap hole 22 has a diameter of 280 mm, and the excavated mud 23 has a depth of about 3 m. When the drilling machine 20 is driven to bring the tip of the tapping bit 1 into contact with the mud 23, the mud 23 is excavated by the tip 3 to generate cutting powder, and the cutting powder is pushed away by the air blow from the air purge hole 6. The bit passes through the inclined groove 11 and is discharged from the distal end face 5 of the bit main body 2 to the base end face 12.
[0021]
As described above, in the tapping bit 1 for tapping, the force toward the base end face 12 is applied to the cuttings by the side surface 11a of the groove 11, and the cuttings are forcibly discharged. Since the groove portion 11 is formed so as to be suitable for discharging the cutting powder, the discharging property of the cutting powder can be improved. Thus, excavation can be performed well, and secondary wear of the tip 3 can be prevented.
[0022]
Further, since the air purge holes 6 are provided at positions where the blowing of the cutting powder by the air blow can be optimally performed, the cutting powder can be efficiently discharged. In addition, the rotation during excavation applies a force to the fixing pin 18 in a direction pressed against the step 19 of the pin hole 15, so that the fixing pin 18 is prevented from dropping out of the pin hole 15, and the guide member 4 is fixed to the bit. It can be securely fixed to the main body 2.
[0023]
In the present embodiment, the grooves 11 and the air purge holes 6 are provided at four locations of the tapping bit 1 for tapping. However, the number of the grooves 11 and the air purge holes 6 may be five or more or three or less. Although the inclination angle of the central axis C of the groove 11 with respect to the rotation axis O is about 25 °, the inclination angle may be appropriately selected depending on the rotation speed of the tapping bit 1 for tapping. At this time, the inclination angle is preferably in the range of 5 ° to 45 °. Although the excavation operation is performed using the fixed drilling machine 20, the excavation operation may be performed using a handheld drilling machine.
[0024]
【The invention's effect】
As described above, according to the counterbore bit for tapping of the present invention, the groove portion of the bit body is formed to be inclined rearward in the rotation direction from the distal end surface toward the proximal end surface, so that the boring during drilling is performed. It is possible to improve powder dischargeability. This makes it possible to excavate satisfactorily without lowering the excavation speed, and to prevent secondary wear of the chips due to cutting powder.
[0025]
An air purge hole is provided at a position where the ratio of the dimension from the air purge hole to the outer peripheral surface of the bit body to the dimension from the air purge hole to the side surface of the guide member is 3.5 to 4.5. An air purge hole is provided at a position where the ratio of the angle from the purge hole to the center of the groove in the forward direction in the rotational direction to the center of the groove in the backward direction in the rotational direction is 1 to 2.8. Therefore, the bobbin powder can be efficiently discharged by the air blow. Thereby, it is possible to excavate satisfactorily without the cuttings accumulating on the tip end surface.
[0026]
In addition, since the step portion is provided behind the pin hole for inserting the fixing pin for fixing the guide member formed on the bit body in the rotation direction, the fixing pin is prevented from falling off, and the guide member is securely attached to the bit body. Can be fixed.
[Brief description of the drawings]
FIG. 1 is a front view of a counterboring bit for tapping in one embodiment of the present invention.
FIG. 2 is a partial cross-sectional view of the tapping counterbore bit taken along line AA in FIG. 1;
FIG. 3 is a cross-sectional view of a fixing point of the counterbore for tapping by a fixing pin, as viewed in a section BB in FIG. 2;
FIG. 4 is an explanatory diagram showing a state of excavation work using a tapping bit for tapping.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Counterbore for tapping 2 Bit body 3 Tip 4 Guide member 5 Tip surface 6 Air purge hole 9 Outer peripheral surface 10 Groove portion 12 Base end surface 15 Pin hole 18 Fixed pin 19 Step

Claims (4)

A bit body attached to the tip of a rotatable rod, a cemented carbide tip implanted in the bit body, a guide member erected at the center of the tip of the bit body, and a tip surface of the bit body A tapping counterbore bit having an air purge hole provided in
A biting counterbore bit for tapping, wherein a groove is formed on an outer peripheral surface of the bit main body, and the groove is inclined rearward in a rotational direction from a distal end surface of the bit main body to a base end surface. In the counterbore bit for tapping according to claim 1,
Regarding the radial arrangement of the air purge hole, the ratio of the dimension from the air purge hole to the outer peripheral surface of the bit body to the dimension from the air purge hole to the side surface of the guide member is 3.5 to 4. 5. A tapping bithing bit characterized in that the air purge hole is provided at a position indicated by No. 5. In the counterboring bit for tapping according to claim 1 or claim 2,
Regarding the rotation direction arrangement of the air purge hole, the ratio of the angle from the air purge hole to the center of the groove in the rotation direction forward to the center of the groove in the rotation direction rearward is The air counterbore is provided at a position from 1 to 2.8. In the counterbore for tapping according to any one of claims 1 to 3,
A pin hole into which a fixing pin for fixing the guide member is inserted is formed in the bit main body so as to extend in the rotation direction. A counterbore for tapping, characterized by being provided with a stepped portion.

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