JPH0645287Y2 - Burnishing drilling tool - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] This invention is a reamer for finishing the inner peripheral surface of a hole made by a drill or the like more precisely, and a burnishing drill for performing vanishing of the inner peripheral surface of the hole at the same time as drilling. The present invention relates to a burnishing drilling tool such as.

[Prior Art] Conventionally, as this type of burnishing drilling tool, for example,
A reamer 31 as shown in Fig. 14 is known.

The reamer 31 is provided with a reamer groove 32 extending along the direction of the central axis L thereof, and an inclined bite portion 33 is provided at the tip. Further, the chamfered portion 33 is provided with a cutting edge 34 radially extending around the central axis L at an edge portion continuous with the reamer groove 32, and an inner surface of the reamer groove 32 continuous with the cutting edge 34 is formed. It is a rake face.

When the reamer 31 is used to finish the inner peripheral surface of the hole previously drilled, the inner peripheral surface of the hole is cut by the cutting edge 34 of the biting portion 33.

Further, as a burnishing drill, for example, a drill groove and a reamer groove are provided in parallel on the outer periphery of the shaft body, and a pressing portion is provided on the rear outer peripheral surface of the reamer groove with respect to the cutting rotation direction of the shaft body. It is known that a substantially conical head portion is provided on the head and a main cutting edge is provided on an edge of the head portion that is continuous with the drill groove. When using this drill, it is possible to position the drill by the apex of the top of the head, and perform punching based on the cutting action of the top and burnishing the inner peripheral surface of the hole based on the pressing action of the pressing part. I was able to.

[Problems to be Solved by the Invention] However, in the conventional reamer 31, since the cutting blades 34 of the bite-shaped portion 33 are provided radially around the central axis L of the reamer 31, cutting by the bite-shaped portion 33 is performed. In case of, the cutting edge 34
Almost all cutting resistance against the rake face of reamer 31
Will act as a torque in the cutting rotation direction X.
Therefore, due to the difference in cutting conditions, the reamer 31 is twisted in the cutting rotation direction X and the chamfered portion 33 is distorted, or the chamfered portion 33 is shaken, resulting in a predetermined hole size and finished surface roughness. There was a fear that could not be obtained.

Further, in the conventional burnishing drill, the feed angle at the time of cutting is limited because the relief angle of the main cutting edge cannot be sufficiently obtained at the conical top. Therefore, when the crown is brought into contact with the surface to be cut while rotating the drill for drilling, the cutting of the main cutting edge near the vertex of the crown becomes worse, and the cutting speed by the main cutting edge decreases. There was a problem of doing.

The present invention has been made in view of the above-mentioned circumstances, and the first purpose is to prevent distortion and runout due to cutting resistance of a chamfered portion for finishing the inner surface of the hole, and to perform mirror finishing of the inner peripheral surface of the hole. A second object is to provide a burnishing drilling tool capable of improving the cutting speed of the main cutting edge by improving the biting of the main cutting edge near the apex of the conical head. To do.

[Means for Solving the Problem] In order to achieve the first object, in the first invention, at least a pair of reamer grooves are provided on the outer periphery of the cylindrical shaft body connected to the shank, and the shaft body A burnishing drilling tool in which a pressing portion extending along the reamer groove is provided on the outer periphery of the shaft body behind the reaming groove with respect to the cutting rotation direction, and the corrosion is continuous in the reaming groove on the tip side outer periphery of the shaft body including the pressing portion. A step portion for attachment is formed, and a surface extending along the radial direction of the shaft main body in the step portion is a rake surface, and the angle formed by the rake surface and the central axis of the shaft main body is not more than a right angle, and the rake surface A forward angle to incline toward the cutting rotation direction, a flank on the outer circumference of the shaft body that is continuous with the rake face, and a cutting edge on the intersecting edge between the rake face and the outer circumference of the shaft body. ing .

In order to achieve the second object, in the second invention, a drill groove and a reamer groove are provided in parallel on the outer periphery of a cylindrical shaft body connected to the shank, and the reamer with respect to the cutting rotation direction of the shaft body. A vanishing in which a pressing part is provided on the outer periphery of the shaft body behind the groove, a substantially conical crown is provided on the tip side of the shaft body, and a main cutting edge is provided on the edge of the crown that is continuous with the drill groove. A drilling tool, in which the main cutting edge is formed continuously from the vertex of the crown to the outer peripheral corner of the shaft body, and the tip angle formed by the main cutting edge near the center of the crown is the main cutting edge near the outer circumference of the crown. It is larger than the tip angle made by and the main cutting edge near the center of the crown has a flank.

[Operation] Therefore, in the first invention, the shank is bite to the chuck of the rotary drilling machine or the like, and the drilling machine is used to insert the shaft body into the hole for finishing the inner surface while rotating the shaft body in the cutting rotation direction. The inner peripheral surface of the hole is cut by the cutting edge of the step portion for attachment. And, since the rake face of the cutting edge is provided with an advancing angle toward the cutting rotation direction and the flank face is provided on the outer periphery of the shaft body continuous with the rake face, the cutting width becomes unequal, The cutting resistance on the rake face is reduced. As a result, twisting of the shaft body in the cutting rotation direction and wobbling of the stepped portion for biting are prevented.

Further, the cutting surface cut by the cutting edge is strongly pressed by the pressing portion. As described above, since the minute unevenness of the cutting surface cut by the cutting edge is gradually crushed through the subsequent pressing step, the finished surface roughness is improved and mirror finishing is performed.

Further, in the second invention, the shank is bitten on a chuck such as a rotary drilling machine, and the top of the head is brought into contact with the work while rotating the shaft body based on the operation of the drilling machine. The main cutting edge of the part of the main cutting edge comes into contact with the work and the work is cut, and the outer surface near the center of the crown does not contact the work due to the flank, so the main cutting edge near the center of the crown is The bite of is improved. Then, by further advancing the shaft body, the work is cut by the main cutting edge near the outer periphery of the crown portion, and a hole having the same outer diameter as the shaft body is made.

Further, following the drilling of the crown portion, the hole is finished by sliding contact with the pressing portion.

[First Embodiment] A first embodiment in which the first and second inventions are embodied in a burnishing drill will be described in detail below with reference to FIGS. 1 to 9.

Now, the burnishing drill of this embodiment is a reamer that performs the burnishing of the inner peripheral surface of the hole at the same time when the hole is drilled.
As shown in the figure, a cylindrical shaft body 2 connected to the shank 1
A pair of drill grooves 3 for discharging cutting chips having a substantially V-shaped cross section are formed on the outer periphery of the so as to extend substantially in parallel along the direction of the central axis L of the shaft body 2. On the outer periphery of the shaft body 2 between the two drill grooves 3, a plurality of (two pairs in this case) reamer grooves 4 for supplying the coolant having a substantially V-shaped cross section are arranged in parallel with each other. It is provided.

Then, the drill groove 3 with respect to the cutting rotation direction X of the shaft body 2
On the outer periphery of the shaft body 2 which is continuous with the rear edge 3a of the reamer and the rear edge 4a of the reamer groove 4 with respect to the cutting rotation direction X, and a pressing portion for pressing the inner peripheral surface of the hole formed by the burnishing drill. The first land 5 and the second land 6 are provided so as to extend along the drill groove 3 and the reamer groove 4, respectively.

As shown in FIG. 1 to FIG. 3, a substantially cone-shaped crown portion 7 is provided on the tip side of the shaft body 2. The apex 8 of the crown 7 is set on the central axis L and arranged at the center of the crown 7.

In the crown portion 7, one of both end edges continuous with each drill groove 3 is chamfered obliquely to provide a thinning 9, and a first end is provided on the other end edge facing the thinning 9.
A main cutting edge 10 including a blade portion 10a, a second blade portion 10b, and a third blade portion 10c is provided.

As shown in FIG. 3, both main cutting edges 10 provided on the edges of both drill grooves 3 are continuously formed from the apex 8 of the crown 7 to the outer peripheral corner 11 of the shaft body 2, and 8 are arranged symmetrically with respect to each other. Further, as shown in FIG. 1, the tip angle θ1 formed by the main cutting edge (first blade portion) 10a near the center of the crown 7 or near the apex 8 is the main cutting edge near the middle of the crown 7. (Second blade part) 10b tip angle θ2
Is set larger than (in this case, θ1 = 160
, Θ2 = 120 degrees). Further, the tip angle θ2 is equal to the crown 7
Is provided larger than the tip angle θ3 formed by the main cutting edge (third blade portion) 10c near the outer circumference, that is, near the outer circumference corner 11. Then, as shown in FIG. 3, the width W of the first blade portion 10a in this case is set to 1/10 of the outer diameter of the shaft body 2.

A first flank 12 is provided on the outer surface of the crown 7 at the rear of the first blade 10a with respect to the cutting rotation direction X of the shaft body 2. Then, as shown in FIG.
The tip angle θ4 formed by the flank 12 is smaller than the tip angle θ1 formed by the first blade portion 10a (in this case, θ4
= 150 degrees). Further, as shown in an enlarged manner in FIG. 8, between the corner portion 10d formed by the first blade portion 10a and the second blade portion 10b and the apex 8, the first blade 10a in the direction orthogonal to the central axis L is formed. Flank
The clearance angle of 12 is constant. The tip angle θ4 is the first
It is possible to reduce the size of the flank 12 to about 140 degrees while ensuring sufficient strength, and the smaller the tip angle θ4, the faster the feed of the burnishing drill.

A second flank 13 is provided on the outer surface of the crown 7 at the rear of the second blade 10b with respect to the cutting rotation direction X.

Further, behind the third blade portion 10c with respect to the cutting rotation direction X, a third flank 13a is provided on the outer side surface of the crown 7.
Is provided.

On the other hand, on the tip side of each first land 5, there is formed a step portion 14 which is recessed by 0.03 to 0.04 mm from the outer diameter of the shaft body 2. The step portion 14 has a predetermined length along the central axis L direction.

Further, a stepped portion 15 for biting is formed at the tip of each second land 6. The depth of the step portion 15 in the radial direction is larger than that of the step portion 14.

Next, the step portion 15 for biting will be described in detail with reference to FIGS.

In the stepped portion 15 for biting, a surface extending along the radial direction of the shaft body 2 is a rake surface 16. As shown in FIG. 5, the angle θ5 formed by the rake face 16 and the axis L1 parallel to the central axis L of the shaft body 2 is formed in an acute angle. Further, as shown in FIG. 6, the rake face 16 is provided with an advance angle θ6 (in this case, θ6 = 10 degrees) so as to be inclined in the cutting rotation direction X.

Further, a cutting edge 17 is provided on a part of an intersecting edge between the rake face 16 and the outer peripheral surface of the shaft body 2. Further, a fourth flank 18 continuous with the cutting edge 17 is provided along the tip of the second land 6, and the flank 18 has a clearance angle θ7 shown in FIG. 7.

Next, the operation of the burnishing drill configured as described above will be described.

Now, in order to drill a workpiece using the burnishing drill of this embodiment, the shank 1 is bite on a chuck such as a rotary drilling machine (not shown). Then, while the shaft body 2 is rotated in the cutting rotation direction X based on the operation of the drilling machine, the top portion 7 thereof is brought into contact with the work. Also, in order to cool the heat generated during cutting, a coolant is supplied to the holed portion.

At this time, first, the first blade portion 10a near the apex 8 of the crown 7 comes into contact with the workpiece, and the workpiece is cut by the blade portion 10a. Then, in the burnishing drill of this embodiment, the first
Since the first flank 12 is provided on the outer side surface of the crown 7 which is continuous with the blade 10a, the biting of the first blade 10a can be improved.

Therefore, it is possible to further improve the bite of the first blade 10a near the apex 8 of the crown 7 with respect to the work. Then, when the burnishing drill is subsequently advanced, the second
The hole is cut by the blade portion 10b and the third blade portion 10c. At this time, the outer peripheral corner 11 of the blade portion 10c in FIG.
Since it is slightly smaller than the outer diameter of the shaft body 2 due to 4, a hole smaller than the outer diameter of the shaft body 2 is to be drilled, leaving a cutting margin for that portion.

Then, when the burnishing drill is further advanced, the stepped portion 15 for biting is slidably contacted with the inner peripheral surface of the hole by the main cutting edge 10 of the crown 7 and the cutting edge 17 causes the inner peripheral surface of the hole to move. The shaving margin is cut.

At this time, even if the cutting waste attached along the main cutting edge 10 is in contact with the inner wall of the cutting margin portion and is scratched, the biting step portion 15 that is continuous behind the main cutting edge 10 is formed. The cutting edge 17 scrapes off the part to be shaved, so that scratches on the inner peripheral surface of the hole can be removed.

Further, since the rake face 16 of the cutting edge 17 is provided with a left-handed forward angle θ6 and a clearance angle θ7 toward the cutting rotation direction X, the cutting widths become unequal, and the cutting on the rake face 16 of the cutting edge 17 is performed. Resistance is reduced. As a result, the stepped portion for eating
The cutting at 15 can be performed accurately to obtain a predetermined hole size and finished surface roughness.

Also, the minute irregularities on the cutting surface cut by the cutting edge 17 are strongly pressed based on the cooperation of the first and second lands 5 and 6 that continuously slide in contact with the cutting of the cutting edge 17. .

Thus, the inner peripheral surface of the hole formed by the main cutting edge 10 of the crown 7 is cut by the cutting edge 17, and the first and second lands 5, 5,
Since it is gradually crushed through a two-step process of strong pressing with 6, the finished surface roughness can be further improved. As a result, the inner peripheral surface of the hole can be mirror-finished.

Further, in the burnishing drill of this embodiment, the main cutting edge 10
The cutting waste that has been cut by is discharged to the outside of the hole through the drill groove 3, the supplied coolant liquid is supplied to the inside of the hole through the reamer groove 4, and then is discharged from the drill groove 3 together with the cutting waste. . Then, the cutting chips cut by the cutting edge 17 of the step portion 15 for biting are sent to the rear of the reamer groove 4 along the slope of the rake face 16 together with the coolant flowing from the tip side of the reamer groove 4. It can be fed into the drill groove 3.

Therefore, the reamer groove 4 adjacent to the biting step portion 15
No cutting chips enter the inside, so that the cutting chips do not hinder the flow of the coolant in the reamer groove 4. Further, when the inner peripheral surface of the hole is pressed by the first and second lands 5,6, cutting debris is not attached to the land 5 and 6 and the inner peripheral surface of the hole is not scratched.

Further, in this embodiment, the first flank 12 is provided on the first blade 10a near the apex 8 of the crown 7, and the first blade 10a
The tip angle θ1 formed by the second blade portion 10 near the outer circumference of the crown 7
By making the angle larger than the tip angle θ2 formed by b to improve the biting of the main cutting edge 10 near the apex 8 with respect to the work, the drilling speed of the main cutting edge 10 of the crown 7 can be improved.

Explaining based on actual drilling data, when drilling is performed using the conventional drill while maintaining the drilling accuracy that is practically no problem, the upper limit of the feed amount of the drill per rotation of the drill is It was at most 0.1 mm.

On the other hand, when drilling was performed using the burnishing drill of this example, the feed amount of the corresponding drill per rotation of the drill could be 0.35 mm. That is,
When drilling is performed using the burnishing drill of this embodiment, it is possible to secure a feed rate of about 3.5 times that of the conventional drill and perform highly accurate drilling. This high-speed feed is realized by reducing the thrust at the center of the shaft body 2 as shown in FIG. 9 (the two-dot chain line in FIG. 9 shows the thrust of a conventional drill). Therefore, it is possible to provide a practical burnishing drill that can perform high-speed drilling as a drill that performs the burnishing of the inner peripheral surface of the hole together with the drilling.

Since the drill of this embodiment can perform high-speed drilling as described above, it can be used as a normal drill, and can perform higher-speed drilling than a normal drill.

In addition, in the burnishing drill of this embodiment, the apex 8 of the crown portion 7 enables easy positioning for drilling,
There is no need to perform troublesome work such as providing a guide hole for positioning in advance.

[Second Embodiment] Next, a second embodiment of the first invention embodied in a cemented carbide reamer will be described with reference to FIG. In each of the following embodiments, the same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The cemented carbide reamer of this embodiment has a shaft body 20 having a substantially flat end surface 20a at its tip, and a twisted reamer groove 21a for discharging cutting waste and two pairs of reamers on the outer circumference of the shaft body 20. The groove 21b is formed. Also, the central axis L of the shaft body 20
A through hole 22 for supplying the coolant liquid is provided on the top.

Then, each reamer groove in the cutting rotation direction X of the shaft body 20
A first land 23 and a second land 24 as pressing portions for pressing the inner peripheral surface of a hole previously drilled by a drill or the like are provided on the outer circumference of the shaft body 20 continuous to the rear of 21a, 21b. Are provided along the reamer grooves 21a and 21b, respectively. Further, on the end surface 20a of the shaft body 20, the reamer groove 21a is formed.
A main cutting edge (not shown) is provided on the end edge continuous with, and a corner portion 23a at the tip of the first land 23 serves as an outer peripheral corner of the main cutting edge.

On the other hand, on the tip end side of the first land 23, a step portion 14 recessed by 0.03 to 0.04 mm from the outer diameter of the shaft body 20 is formed. Further, a stepped portion for biting is provided on the tip side of each second land 24.
15 are formed. The depth of the step portion 15 in the radial direction is larger than that of the step portion 14.

In the stepped portion 15 for biting, the angle θ5 formed by the rake face 16 and the axis L1 parallel to the central axis L is provided at a substantially right angle. Further, the forward angle θ6 (in this case, θ6
= 30 degrees) is provided.

Further, a cutting blade 17 is provided on the intersecting edge between the rake face 16 and the outer peripheral surface of the shaft body 20. Further, a fourth flank 18 continuous with the cutting edge 17 is provided at the tip of the second land 24.

Therefore, in order to use the cemented carbide reamer of this embodiment, the tip of the shaft body 20 is fitted into a hole previously drilled by a drill or the like, and the coolant liquid is supplied to the drilled portion through the coolant liquid supply through hole 22. To supply.

At this time, first, the inner peripheral surface of the hole is cut by the main cutting edge provided on the end surface 20a of the shaft body 20, leaving a cutting margin for the step portion 14.

Subsequently, the cutting margin left on the cutting surface is cut by the cutting edge 17 of the bite step portion 15.

At this time, even if the inner wall of the shaving margin is scratched by the contact of cutting chips attached along the main cutting edge, the cutting edge of the stepped portion 15 for biting that is continuous behind the main cutting edge. 17
With this, it is possible to scrape off the scraped portion, and it is possible to remove scratches on the inner peripheral surface of the hole.

Further, the rake face 16 of the cutting edge 17 is provided with an advance angle θ6 toward the cutting rotation direction X, and the fourth flank face 18 continuous with the cutting edge 17 is provided, so that the cutting width becomes unequal. Blade 17
The cutting resistance on the rake face 16 of the is reduced. As a result, twisting of the shaft body 20 in the cutting rotation direction X can be prevented, distortion of the biting step portion 15 can be prevented, and shake can be prevented. As a result, it is possible to accurately cut the biting step portion 15 and obtain a predetermined hole size and a finished surface roughness.

In this way, the inner peripheral surface of the hole previously drilled is gradually crushed through the two-step process of cutting by the cutting edge 17 and strong pressing by the first and second lands 23, 24. The finished surface roughness can be further improved. As a result, the inner peripheral surface of the hole can be mirror-finished.

Further, in the cemented carbide reamer of this embodiment, the cutting scraps cut by the main cutting edge are discharged to the outside of the hole through the reamer groove 21a and cut by the cutting edge 17 of the bite step portion 15. The cutting waste is sent along the rake face 16 into the rear reamer grooves 21a and 21b, and is discharged to the outside of the hole through the reamer grooves 21a and 21b. At the same time, the coolant liquid supplied from the through holes 22 is discharged together with the cutting chips through the reamer grooves 21a and 21b.

The first device and the second device are not limited to the above-described embodiments, and a part of the configuration may be appropriately changed without departing from the spirit of the invention and implemented as follows. You can also

(1) As another embodiment of the first invention, the eleventh embodiment
As shown in the figure, the crown portion 7 of the shaft body 2 may be applied to a drill having a substantially flat shape.

(2) As another embodiment in which the first invention is embodied,
As shown in the drawing, it may be applied to a reamer having a pair of drill grooves 3 for discharging cutting chips and a pair of reamer grooves 4 for supplying a coolant, which are parallel to each other along the central axis of the shaft body 2.

(3) As another embodiment embodying the first invention,
As shown in the figure, a reamer groove 4 for discharging cutting waste that is parallel to the central axis of the shaft body 2 may be provided, and the outer peripheral portion 25 of the shaft body 2 may be used as a reamer for a coolant supply passage. .

(4) Reamer grooves 21a, 21b on the shaft body 20 of the second embodiment
It may be applied to a reamer having a reamer groove having a twist in the opposite direction.

(5) First and second in the shaft body 20 of the second embodiment
The stepped portion 15 for biting may be provided on all the leading end sides of the lands 23, 24.

(6) As another embodiment embodying the first invention, the present invention can be applied to a reamer in which three lands 5,23 and three lands 6,24 are alternately provided on the shaft body 2,20. Good.

(7) As another embodiment embodying the second invention, the tip angles θ1, θ2, θ3 in the first embodiment may be set by increasing or decreasing respectively.

(8) As another embodiment embodying the second invention, the width W of the first blade portion 10a in the first embodiment may be set to be increased or decreased.

[Effects of the Invention] As described in detail above, according to the first invention, it is possible to reduce the cutting resistance in the chamfered portion for finishing the inner surface of the hole and prevent the distortion and the shake of the chamfered portion. In addition to the excellent effect that the hole size and the finished surface roughness can be improved, the inner peripheral surface of the hole can be mirror-finished. Further, according to the second invention, it is possible to improve the biting of the main cutting edge in the vicinity of the center of the crown and to improve the cutting speed by the main cutting edge, so that high-accuracy drilling can be performed at high speed. It has the excellent effect that it can be performed in.

[Brief description of drawings]

1 to 9 are drawings showing a first embodiment embodying the first and second inventions, in which FIG. 1 is a partially cutaway front view of the tip of a shaft body, and FIG. 1 is a left side drawing, FIG. 3 is a plan view of the crown, FIG. 4 is a front view of the shaft body, and FIG.
FIG. 7 is an enlarged partial cutaway view of the stepped portion for biting, FIG. 8 is an enlarged partial cutaway view of the crown, and FIG. 9 is a diagram for explaining thrust distribution at the crown. FIG. 10 and FIG. 11 are partially cutaway front views of the tip of the shaft body showing another embodiment, FIG. 12 and FIG.
FIG. 13 is a plan view of the tip of a shaft body showing another embodiment of the present invention. FIG. 14 is a partially cutaway front view showing a conventional example. 1 …… Shank, 2, 20 …… Shaft body, 3 …… Drill groove, 4,
21a, 21b …… Reamer groove, 23 …… First land, 6,24 ……
Second land (6 and 23, 24 constitute a pressing portion), 7 ... top portion, 8 ... apex, 10 ... main cutting edge, 10a
...... First blade, 10b …… Second blade, 11 …… Outer peripheral corner, 12 …… First flank, 15 …… Diffusion step, 16…
... rake face, 17 ... cutting edge, 18 ... fourth flank, L ...
Center axis, X ... Cutting rotation direction, θ1, θ2 ... Tip angle,
θ5: angle, θ6: forward angle.

Claims (2)

[Scope of utility model registration request] 1. A shaft body (2) having at least a pair of reamer grooves (4) (21a, 21b) provided on the outer periphery of a cylindrical shaft body (2) (20) connected to a shank (1).
A press extending along the reamer groove (4) (21a, 21b) on the outer circumference of the shaft body (2) (20) behind the reamer groove (4) (21a, 21b) with respect to the cutting rotation direction (X) of the (20). A burnishing drilling tool provided with parts (6) (23, 24), the shaft body (2) (2) including the pressing parts (6) (23, 24).
The stepped portion (15) for biting which is continuous in the reamer groove (4) (21a, 21b) is formed on the outer periphery of the tip side of (0), and the shaft body (2) (20) is formed at the stepped portion (15). The rake face (16) is defined as the face extending along the radial direction of).
And the central axis (L) of the shaft body (2) (20) make an angle (θ5) less than a right angle, and the rake face (1
6) is provided with an advance angle (θ6) so as to be inclined in the cutting rotation direction (X), and further, a flank (18) is provided on the outer periphery of the shaft body (2) (20) continuous with the rake face (16). ) Is provided, and a cutting blade (17) is provided on the intersecting edge of the rake face (16) and the outer peripheral surface of the shaft body (2) (20). 2. A drill groove (3) and a reamer groove (4) are provided in parallel on the outer periphery of a cylindrical shaft body (2) connected to the shank (1), and a cutting rotation direction of the shaft body (2). A pressing portion (6) is provided on the outer periphery of the shaft body (2) behind the reamer groove (4) with respect to (X), and a substantially conical crown portion (7) is further provided on the tip side of the shaft body (2). A burnishing drilling tool, which is provided with a main cutting edge (10) on an edge of the crown (7) that is continuous with the drill groove (3), wherein the main cutting edge (10) is the crown ( From the apex (8) of 7) to the outer peripheral corner (11) of the shaft body (2),
The tip angle (θ1) formed by the main cutting edge (10a) near the center of the crown (7) is defined as the main cutting edge (10) near the outer circumference of the crown (7).
It is provided larger than the tip angle (θ2) formed by b), and the flank (1) is attached to the main cutting edge (10a) near the center of the crown (7).
A burnishing drilling tool characterized by having 2).