JPH09174542A - Hole working tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that the screw engagement for fixing a hole processing cylinder to a cylinder holder and the screw engagement for fixing the cylinder holder to a tool middle shaft element are locked in by the rotatory power of a tool. SOLUTION: A hole processing tool is equipped with a cylinder fixing mechanism wherein a tool middle shaft element 5 having a shank 4 provided to the base end thereof is inserted into the boss part 19 of the cylinder holder 6 holding one end part of a cylindrical hole processing cylinder 7 so as to be freely detachable from the shaft leading end of the boss part 19 and the rotation prescribing member 22 prescribing the rotation of the cylinder holder 6 to the tool middle shaft element 5 is provided between the tool middle shaft element 5 and the boss part 19. A nut member 10 is threaded with the outer periphery of the tool middle shaft element 5 on the base end side of the cylinder holder 6 and subjected to clamping operation to fix not only the hole processing cylinder 7 to the cylinder holder 6 but also the cylinder holder 6 to the tool middle shaft element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole drilling tool used when a relatively large hole such as a large diameter hole required for piping of an air conditioner is provided on a wall surface of a building.

[0002]

2. Description of the Related Art A hole drilling tool of this type has a cylindrical hole drilling tube via a disk-shaped tube holder on a tool shaft body having a shank at the base end and a center drill at the tip end. They are mounted concentrically. In such a hole drilling tool, since it is necessary to take out the material clogged inside the hole drilling cylinder after the drilling work, it is preferable that the hole drilling cylinder can be removed from the cylinder holder.

A conventional tool having such a structure is shown in FIG. In this tool 40, a cylinder holder 41 and a hole-machining cylinder 42 are formed separately, and the connection between these two members 41, 42 is screwed to the tip of a tool shaft body 43 that penetrates the cylinder holder 41. Scale control wheel 44
And the expansion / contraction wheel body 45 arranged between the expansion / contraction operation wheel 44 and the hole forming cylinder 42.

That is, the tool shaft body 43 and the cylinder holder 4
1 is not screw-engaged with each other, and when the tool shaft body 43 is rotated clockwise in the tube holder 41, the expansion / contraction operation wheel 44 screwed to the tip of the tool shaft body 43 is brought close to the tube holder 41. It is like this. Therefore, the expansion / contraction operation wheel 44
The expansion / contraction ring body 4 via the inclined surface engaging in a wedge shape.
5 is expanded in the radial direction and is pushed into the cylindrical holder 41 to fix the cylindrical holder 41 and the hole-processing cylinder 42.

With this conventional tool 40, when removing the material clogged inside the hole forming cylinder 42 after the boring operation,
By rotating the tool shaft body 43 counterclockwise relative to the expansion / contraction operation wheel 44, the hole forming cylinder 42 can be removed from the cylinder holder 41. However, with this tool 40, the screw engagement between the tip of the tool shaft body 43 and the expansion / contraction operation wheel 44 is strongly tightened by the rotational force applied to the shank 46 of the tool shaft body 43 during the drilling operation. When attempting to loosen the expansion / contraction operation wheel 44 as described above, it is necessary to rotate the tool center shaft body 43 with a strong force, which poses a problem that the work is difficult and complicated.

As a solution to this problem, for example, there is one disclosed in Japanese Patent Laid-Open No. 5-253721. In this conventional technique, a cylinder holder is screwed to a tool shaft body, and is a member that is displaceable between a first position and a second position along the axial direction in the cylinder holder. By providing a pressing member having a pressing surface that pushes and expands the expansion / contraction wheel body at the position 1 and a release surface that allows the expansion / contraction wheel body to reduce in diameter at the second position, the cylinder holder is provided. On the other hand, the pressing member for fixing the hole forming cylinder is not directly affected by the rotation of the tool, and the hole forming cylinder can be easily removed from the cylinder holder.

[0007]

However, also in this conventional tool, the cylinder holder provided with the pressing member is screwed to the tool shaft body, and the rotation of the tool causes a gap between the tool shaft body and the cylinder holder. Since the screw engagement is strongly tightened, it becomes extremely difficult to disassemble these both members, and the work of attaching and detaching the cylinder holder is complicated.

Therefore, the present invention is intended to facilitate not only the removal work of the cylinder holder and the bored cylinder but also the removal work of the tool shaft body and the cylinder holder. To aim.

[0009]

In order to achieve the above object, the present invention takes the following technical means. That is, in the hole drilling tool of the present invention, the tool shaft having the shank on the base end side,
A boss portion of a cylinder holder that holds one end of a cylindrical hole-machining cylinder is removably inserted from the shaft tip side of the boss portion, and a tool is inserted between the tool shaft body and the boss portion. A rotation restricting member that restricts rotation of the cylinder holder with respect to the center shaft is provided, and a nut member is screwed onto the outer periphery of the tool center shaft at the base end side of the cylinder holder, and the nut member is fastened. Thus, a hole fixing cylinder is fixed to the cylinder holder, and a cylinder fixing mechanism for fixing the cylinder holder to the tool shaft is provided.

According to the present invention, the hole processing cylinder can be removed from the cylinder holder by loosening the nut member, and the nut shaft can be removed from the boss portion of the cylinder holder to the shaft tip side by removing the nut member from the tool shaft body. It will be possible to remove it. The rotation of the cylinder holder is restricted by the rotation restricting member with respect to the tool shaft, and the rotational force of the tool shaft is transmitted to the hole machining cylinder through the rotation restricting member. Since the screw engaging portion does not exist in the force transmission path, the screw engaging portion is not strongly tightened by the rotation of the tool. That is, the nut member is not strongly tightened by the rotation of the tool, and therefore, not only the hole processing cylinder can be removed from the cylinder holder, but also the cylinder holder can be easily removed from the tool shaft body.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Normally, a center drill located at the shaft center of a hole drilling cylinder is detachably mounted on the tip end side of a tool shaft body to ensure reliability of tool centering during drilling work. To improve. The rotation restricting member is attached to the boss portion so as to project radially inward, and an engaging groove extending in the axial direction with which the rotation restricting member engages is formed on the outer periphery of the tool shaft body, thereby restricting the rotation of both of them. However, it is preferable that a rotation restricting member is provided on the tool shaft body in a radially outwardly projecting manner to form an engagement groove on the inner circumference of the boss portion.

As the cylinder fixing mechanism, an expansion / contraction ring body fitted in the hole forming cylinder is arranged on the shaft tip side of the cylinder holder, and at least a nut member is provided on the shaft tip side of the expansion / contraction ring body. An expansion / contraction operation wheel provided at the tip of the tool shaft body is arranged so as to move in the axial direction together with the tool shaft body in the axial direction during the fastening operation. The taper surface that pushes and expands the expansion and contraction ring body in the radial direction when the holder and the expansion and contraction operation wheel are relatively close to each other,
It may be provided on the outer circumference of the cylinder holder and the expansion / contraction operation wheel. The tapered surface may be provided only on either the cylinder holder or the expansion / contraction operation wheel. The expansion / contraction operation wheel provided at the tip of the tool shaft body may be provided integrally with the tool shaft body or may be a separate body.

In such a cylinder fixing mechanism, when the nut member is fastened, the tool shaft is axially moved toward the base end with respect to the cylinder holder, and the expansion / contraction operation wheel is axially moved toward the base end together with the tool shaft. To be done. That is, the tube holder and the expansion / contraction operation wheel are relatively close to each other, and the expansion / reduction ring body is radially expanded by the tapered surfaces formed on the tube holder and the expansion / contraction operation wheel, and the tube holder and the hole forming tube are inserted through the expansion / reduction wheel body. And are firmly fixed.

On the other hand, in such a fixed state, the cylinder holder is strongly tightened in the axial direction between the expansion / contraction operation wheel provided at the tip of the tool shaft body and the nut member screwed to the tool shaft body. Therefore, the fastening operation of the nut member described above also fixes the shaft body of the tool and the tubular holder. In such a cylinder fixing mechanism, since the structure of the constituent members is simple and the number of parts can be reduced, productivity can be improved, assembly workability can be improved, and cost can be reduced. Further, the screw groove is also formed at one place where the tool shaft body and the nut member are screwed together, and the number of screw groove processed portions is smaller than that of the invention disclosed in Japanese Patent Laid-Open No. 5-253721. This also contributes to productivity improvement and cost reduction.

Further, a peripheral groove is formed on the inner peripheral surface of the hole machining cylinder,
By providing a convex portion on the outer periphery of the expansion / contraction operation wheel that engages with the circumferential groove when being expanded in the radial direction, when the nut member is fastened to fix the hole forming cylinder to the cylinder holder, the convex By engaging the portion and the circumferential groove, it is possible to reliably prevent the hole processing cylinder from coming off the cylinder holder.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show a hole drilling tool 1 according to an embodiment of the present invention. The tool 1 has a shank 4 on a base end side and a drill mounting cylinder shaft portion 3 on a tip end side. The central shaft body 5 is provided. The shaft body 5 is made of carbon tool steel.

As shown in FIGS. 1, 2 and 4, the shank 4 of the tool shaft 5 has a torque transmission groove 15 for mounting on a rotary hammer drill having a key groove shape parallel to the axis on the outer peripheral surface thereof. Are provided at two intervals of 180 degrees over substantially the entire length thereof, and tool stroke regulating grooves 16 are provided between the grooves 15 in parallel and at equal intervals toward the shaft end.
The restricting groove 16 restricts the axial movement amount and the return amount, that is, the stroke of the tool 1 when hit by a hammer drill. The groove bottom is as shown in FIG. 2 so that the locking ball can be engaged. And both ends in the axial direction are closed.

That is, the torque transmission groove 15 and the stroke restriction groove 16 are alternately provided at 90 degree intervals. Further, the shank 4 is further provided with three torque transmission surfaces 17 that can be mounted on a chuck (not shown) of the rotary drill at equal circumferential intervals (120 degree intervals), of which one surface 17A is circumferential. The center is the stroke restriction groove 1
6 are provided on both sides in the axial direction of the regulating groove 16 so as to coincide with the center in the width direction.

Therefore, although the side walls of the grooves 15 and 16 are partly lowered in height due to the formation of the torque transmitting surface 17, the torque transmission and the stroke regulation are not hindered at all, and the side walls are allowed to function sufficiently. It can be attached to both rotary hammer drills and rotary drills. A center drill 2 is inserted and held from the tip side of the drill into the drill mounting cylinder shaft portion 3 of the tool shaft body 5, and the drill 2, the cylinder shaft portion 3 and the shank 4 are arranged on one axis along the rotation axis. ing. Further, a drill fixing bolt 14 is screwed onto the cylindrical shaft portion 3 so that the drill 2 is detachably and replaceably fixed.

Further, on the outer periphery of the cylinder shaft portion 3 of the tool shaft body 5, from its base end side, a nut member 10 screwed to the cylinder shaft portion 3, a cylinder holder 6 held by the cylinder shaft portion 3, An expansion / contraction wheel 8 externally fitted to the holder 6 and an expansion / contraction operation wheel 11 provided at the tip of the tubular shaft portion 3 are provided. Further, a cylindrical hole drilling cylinder 7 which is concentric with the center drill 2 is externally fitted to the cylinder holder 6.

A male screw portion 12 is formed on the outer peripheral surface of the cylindrical shaft portion 3 on the base end side, and the male screw portion 12 and the nut member 1 are formed.
The female screw portion formed on the inner peripheral surface of 0 is screw-engaged. The shank 4 of the tool shaft body 5 has the smallest diameter, and the diameter of the cylinder shaft portion 3 gradually increases from the base end side to the tip end side. The provided flange portion 13 has the largest diameter.

As shown in FIGS. 6 and 7, the barrel holder 6 has a boss portion 19 in the center of which a through hole 18 into which the barrel shaft portion 3 of the center rod 5 is fitted is formed. The flange portion 20 extends radially from the outer peripheral end of the boss portion 19. The boss portion 19 projects toward the base end side with respect to the flange portion 20. In addition, on the outer peripheral portion of the flange portion 20, the side opposite to the boss portion 19 (that is, the shaft tip side)
A ring-shaped expansion / contraction ring body receiving portion 21 protruding inward is integrally provided.

As shown in FIG. 1, the outer peripheral side of the expansion / contraction ring body receiving portion 21 can be removably fitted into the hole forming cylinder 7, and the diameter thereof is reduced toward the tip end side of the shaft. The tapered surface 21A is formed, and the tapered surface 21A is in contact with the tapered surface 8A formed on the peripheral edge of the expansion and contraction body 8 on the base end side. In addition, the boss portion 19 of the tube holder 6
A screw-shaped rotation restricting member 22 is screwed from the radially outer side, and the member 22 slightly projects radially inward from the inner peripheral surface of the boss portion 19. On the other hand, on the outer peripheral surface of the cylindrical shaft portion 3 of the center shaft body 5, as shown in FIG. 4, a groove 22a extending axially from the base end portion toward the distal end is provided.
The rotation of the cylindrical holder 6 with respect to the center shaft body 5 is restricted by the restriction member 22 being engaged with the groove 22a, but relative movement in the axial direction is allowed.

The boss portion 19 is provided with engaging ball fitting holes 23 at a plurality of circumferential positions (four positions in the illustrated embodiment), and the fitting holes 23 are formed of coil springs. The elastic body 24 and the locking ball 25 are stored. The locking ball 25 has a part thereof slightly protruding from the end face of the boss portion 19 on the base end side, and is always biased in the protruding direction (base end side) by the elastic body 24.

Further, on the outer peripheral portion of the flange portion 20 of the cylinder holder 6, a large number of cutting blade fitting notches 27 are provided in correspondence with a large number of cutting blades 26 circumferentially provided at both axial ends of the hole forming cylinder 7. The relative rotation between the cylinder holder 6 and the hole machining cylinder 7 is reliably regulated by the engagement of the cutting blade 26 and the notch 27. A peripheral groove 28 having a concave cross section is provided on the inner peripheral surface of the hole machining cylinder 7 in the vicinity of both axial ends thereof.

As shown in FIG. 3, the expansion / contraction ring 8 is a C-shaped split ring in which a slit 29 is provided at one position on the outer peripheral portion so as to reach both ends in the axial direction. Tapered surfaces 8A and 8B are formed at both ends in the axial direction, respectively, the diameters of which are reduced from the edge toward the center, and a large number of shallow grooves 30 are provided on the outer periphery at a slant with respect to the axis and the tapered surfaces are formed. Engaging projections 31 are provided at the end portions on the 8B side, respectively, and the projections 31 are fitted into and engaged with the circumferential groove 28 of the hole-machining cylinder 7 to ensure that the hole-machining cylinder 7 is removed from the cylinder holder 6. It is supposed to block.

As shown in FIG. 5, the nut member 10 is provided with a large number of concavities and convexities 35 on the entire end surface (the end surface on the shaft tip side) facing the boss portion 19 and is engaged in the recessed portion. The stop ball 25 is fitted and locked, and the nut member 1
It is designed to prevent 0 from loosening naturally. The expansion / contraction operation wheel 11 has a disk shape, and an insertion hole 11a into which the cylindrical shaft portion 3 of the tool shaft body 5 is fitted is provided in the central portion thereof. On the other hand, a flange portion 13 is projectingly provided on the outer periphery of the tip end portion of the tubular shaft portion 3, and the flange portion 13 is in contact with the end face of the expansion / contraction operation wheel 11 on the tip end side of the shaft.
By fastening 0, the central shaft 5
Is configured so that the expansion / contraction operation wheel 11 moves relatively to the proximal end side together with the center shaft body 5 when the axial movement moves to the proximal end side. In the illustrated embodiment, the expansion / contraction operation wheel 11 is attached to the cylindrical shaft portion 3.
However, the expansion / contraction operation wheel 11 may be provided integrally with the tip end portion of the cylindrical shaft portion 3.

Further, on the outer peripheral surface of the expansion / contraction operation wheel 11, a taper surface 36 fitted to the taper surface 8B of the expansion / contraction wheel body 8 is formed.
When the flange portion 20 of the tube holder 6 and the expansion / contraction operation wheel 11 are relatively close to each other by fastening the nut member 10, the expansion / contraction operation wheel 11 pushes the expansion / contraction wheel body 8 in the radial direction and expands it. Then, the cylinder holder 6 and the hole-processing cylinder 7 are fixed via the expansion / contraction ring body 8.

When assembling the hole drilling tool 1 in the above embodiment, first, the expansion / contraction ring 8 is fitted on the ring receiving portion 21 of the tube holder 6 and the expansion / contraction operation wheel is attached to the shaft tip side of the ring 8. Insert 11. Then, from the tip end side of the shaft (from the bottom in FIGS. 1 and 3) into the through-hole mounting hole portion in the center of the cylinder holder 6, the expansion / contraction wheel body 8, and the expansion / contraction operation wheel 11.
Insert the shaft body 5 in the tool. At this time, the rotation regulating member 2
2 is engaged with the concave groove 22a provided in the cylindrical shaft portion 3.

The male screw portion 12 formed on the cylindrical shaft portion 3
Is exposed to the base end side of the boss portion 19 of the tube holder 6, the nut member 10 is lightly screwed into the male screw portion 12,
The nut member 10 prevents the tool shaft body 5 from coming off the tube holder 6. In addition, in this way, the nut member 1
When 0 is lightly screwed, the expansion / contraction ring body 8 is configured so as not to be radially expanded.

Next, one end of the hole forming cylinder 7 is connected to the expansion / contraction ring 8
And, it is fitted around the expansion / contraction operation wheel 11. At this time, the cutting blade 26 is fitted into the cutout portion 27 provided on the outer circumference of the flange portion 20 of the cylinder holder 6 to prevent the cylinder holder 6 and the hole machining cylinder 7 from rotating, and to position and protect the cutting blade 26. And can be obtained. Therefore, when the nut member 10 is rotated and tightened in the screw tightening direction while holding the hole processing cylinder 7 by hand and holding it in a non-rotatable state, the expansion / contraction operation wheel 11 moves to the flange portion 20 side of the cylinder holder 6. The expansion / reduction ring body 8 is pushed and expanded by this, the engaging convex portion 31 of the ring body 8 is fitted into the circumferential groove 28 of the hole forming cylinder 7, and the outer peripheral surface of the expansion / reduction ring body 8 is hole formed. The inner peripheral surface of the cylinder 7 is pressed closely to fix the whole assembly relationship.

At this time, the unevenness 3 on the end surface of the nut member 10
5, a locking ball 25 is locked, but the elastic body 2
Since the locking ball 25 is pushed against the urging force of 4, the nut member 10 can be easily rotated. Then, when the nut member 10 naturally tries to loosen, the locking ball 25 fits into the unevenness 35, whereby the rotation of the nut member 10 with respect to the tube holder 6 is prevented, and a locking effect is produced.

When the hole forming cylinder 7 is detached from the cylinder holder 6, the nut member 10 is rotated in the direction in which the screw is loosened while the hole forming cylinder 7 is held in a non-rotatable state, so that the expansion / contraction ring body 8 is rotated. Reducing the diameter by elasticity, the expansion / contraction operation wheel 1
1 is pushed in the direction away from the cylinder holder 6, and the expansion / contraction ring 8
Since a gap is formed between the outer peripheral surface of the hole forming cylinder and the inner peripheral surface of the hole forming cylinder 7, the hole forming cylinder 7 can be easily extracted. In addition,
When performing the work of taking out the material clogged in the hole forming cylinder 7 after the punching work, it is only necessary to remove the hole forming cylinder 7, so that it is not necessary to completely remove the nut member 10 from the cylinder shaft portion 3. . However, when performing the attachment / detachment exchange work of the cylinder holder 6 mounted on the tool shaft body 5, the nut member 1
0 may be completely removed from the cylinder shaft portion 3 and the center shaft body 5 may be extracted from the cylinder holder 6.

The present invention is not limited to the configuration of the above embodiment, and the design can be changed appropriately. For example, the scaling wheel 8
Can be integrally provided on the outer periphery of the flange portion 20 of the tube holder 6, or can be a split ring body divided into a plurality in the circumferential direction. Further, a retaining ring that prevents the tool center shaft body 5 from coming off from the boss portion 19 of the cylinder holder 6 toward the shaft tip side can be detachably attached.

[0035]

According to the present invention, the tool shaft having the shank on the base end side is attached to the boss portion of the cylinder holder for holding one end of the cylindrical hole-machining cylinder from the shaft tip side of the boss portion. A rotation restricting member that restricts rotation of the cylinder holder with respect to the tool shaft is provided between the tool shaft and the boss, and is inserted between the tool shaft and the boss. A nut member is screwed onto the outer periphery of the center shaft body, and a hole fixing cylinder is fixed to the cylinder holder by fastening and operating the nut member, and a cylinder fixing mechanism that fixes the cylinder holder to the tool center body. Is equipped with
The rotation driving force of the tool is not transmitted to the nut member for both fixing the hole processing cylinder to the cylinder holder and fixing the cylinder holder to the tool shaft body, so that the nut member is not tightly tightened. Therefore, it is possible to easily perform the operation of loosening the nut member, and it is possible to easily perform not only the work of removing the hole machining cylinder from the cylinder holder, but also the work of removing the cylinder holder from the tool shaft body.

Further, as a cylinder fixing mechanism, an expansion / contraction ring body fitted in the hole forming cylinder is arranged on the shaft tip side of the cylinder holder, and at least a nut member is tightened on the shaft tip side of the expansion / contraction ring body. The expansion / reduction operation wheel provided at the tip of the tool inner shaft body is arranged so as to move in the axial direction together with the tool inner shaft body in the axial direction, and the nut member is tightened to operate the cylinder holder and the expansion / reduction operation wheel. If the taper surface that pushes and expands the expansion / contraction ring body in the radial direction when the and are relatively close to each other is provided on the outer circumference of the cylinder holder and / or the expansion / contraction operation wheel, the number of constituent members can be reduced and the structure can be simplified. Can achieve the above effects, and can improve productivity and reduce cost.

Further, a peripheral groove is formed on the inner peripheral surface of the hole machining cylinder,
In the case where the outer periphery of the expansion / contraction operation wheel is provided with a convex portion that engages with the circumferential groove when expanded in the radial direction, it is possible to reliably prevent the hole processing cylinder from slipping out in the axial direction with respect to the cylinder holder. it can.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of a hole drilling tool according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the shank, which is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an exploded vertical sectional view of the tool.

FIG. 4 is a side view of a tool shaft body.

FIG. 5 is a bottom view of the nut member.

FIG. 6 is a plan view of a cylinder holder.

7 is a cross-sectional view taken along the line BB of FIG.

FIG. 8 is a side view showing a part of the expansion / contraction ring.

FIG. 9 is a cross-sectional view showing an example of a conventional hole drilling tool.

[Explanation of symbols]

 1 Hole Processing Tool 4 Shank 5 Tool Medium Shaft Body 6 Tube Holder 7 Hole Processing Tube 8 Expansion / Reduction Ring Body 10 Nut Member 11 Expansion / Reduction Operation Wheel 19 Boss Section 22 Rotation Restriction Member 28 Circumferential Groove 31 Convex Section 36 Tapered Surface

Claims (3)

[Claims] 1. A tool shaft body (5) having a shank (4) on the base end side is attached to a boss portion (19) of a cylinder holder (6) holding one end of a cylindrical hole machining cylinder (7). The boss portion (19) is inserted from the shaft tip side so as to be removable, and between the tool shaft body (5) and the boss portion (19).
A rotation restricting member (22) for restricting rotation of the cylinder holder (6) with respect to the tool shaft body (5) is provided, and a nut is provided on the outer periphery of the tool shaft body (5) at the base end side of the cylinder holder (6). The member (10) is screwed, and the hole processing cylinder (7) is fixed to the cylinder holder (6) by fastening and operating the nut member (10), and the tool shaft body (5).
A hole drilling tool, characterized in that it is provided with a cylinder fixing mechanism for fixing the cylinder holder (6). 2. A tool shaft body (5) having a shank (4) on the base end side is attached to a boss portion (19) of a cylinder holder (6) which holds one end of a cylindrical hole machining cylinder (7). The boss portion (19) is inserted from the shaft tip side so as to be removable, and between the tool shaft body (5) and the boss portion (19).
A rotation restricting member (22) for restricting rotation of the cylinder holder (6) with respect to the tool shaft body (5) is provided, and a nut is provided on the outer periphery of the tool shaft body (5) at the base end side of the cylinder holder (6). A member (10) is screwed, and an expansion / contraction ring (8) fitted in the hole forming cylinder (7) is disposed on the shaft tip side of the cylinder holder (6). ) On the shaft tip side,
A scaling wheel provided at the tip of the tool shaft body (5) so as to move in the axial direction with respect to the tubular holder (6) together with the tool shaft body (5) when fastening the nut member (10) at least. (11) is provided, and when the nut member (10) is fastened to bring the cylinder holder (6) and the expansion / contraction operation wheel (11) into close proximity to each other, the expansion / reduction wheel body (8) is radially moved. A hole drilling tool characterized in that a taper surface (21A, 36) for expanding is provided on the outer periphery of the cylinder holder (6) and / or the expansion / contraction operation wheel (11). 3. A peripheral groove (2) is formed on the inner peripheral surface of the hole-machining cylinder (7).
8) is formed, and a protrusion (31) that engages with the circumferential groove (28) when radially expanded is provided on the outer periphery of the expansion / contraction operation wheel (11). The hole drilling tool according to claim 2, which is characterized.