JP2003291012A - Throwaway type drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throwaway type drill allowing rigid fixing of a cutting head part, while preventing damage. <P>SOLUTION: An engagement part is provided with either one of the cutting head part 5 or a tool body 2, while receiving parts engageable with the engagement part are provided with the other one. The engagement part is equipped with an axially protruding shaft part, connecting surfaces 16 provided respectively on the confronting side surfaces of the shaft part, and a differently leveled part 18 provided to the vicinity of the connecting surfaces 16. The receiving parts are equipped with a recessed part engaged with the shaft part, abutting surfaces 23 formed face to face in the recessed part and engaged with the respective connecting surfaces 16 of the shaft part, and a receiving step part 24 provided to the vicinity of the abutting surfaces and engaged with the differently leveled part 18 to transmit turning force. The cutting head part 5 is fixed on the tool body by fastening a fastening bolt 30 from the axial direction with engaging the engagement part and the receiving part. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type drill in which a cutting head portion having a cutting edge can be replaceably attached to a tool body.

[0002]

2. Description of the Related Art Conventionally, for example, a utility model registration No. 3054444 as a throw away type drill in which a cutting head portion having a cutting edge can be replaceably mounted on a tool body.
There is one described in the publication. This throw-away type drill has elastic slits on the tool shank at the mutual connection part of the cutting head part and the tool shank, which consists of the tip side area of the drill, and a pair of concave concave fixings for connection facing the both sides of the elastic slit. Forming a pair of walls and a pair of torque transmission walls for transmitting torque to the cutting head portion, and forming a pair of convex fixing walls engaging the fixing wall of the tool shank and a torque transmitting wall of the tool shank on the cutting head portion. It has a pair of torque transmission walls which fit. The minimum distance between the facing concave fixed walls is set wider than the width of the convex fixed walls. When connecting the cutting head part to the tool shank, the convex fixing walls of the cutting head part are passed through the gap of the concave fixing wall of the tool shank so that both fixing walls are coaxial and orthogonal to each other, and then the cutting head part. When is rotated in the direction opposite to the rotating direction of the tool body, the torque transmitting wall of the cutting shank portion abuts on the torque transmitting wall of the tool shank portion, and the convex fixing wall and the concave fixing wall are connected. The two fixing walls are connected while elastically deforming and expanding the elastic slit of the tool body, whereby the cutting head part and the tool shank are elastically connected.

[0003]

However, in such a structure, the connection between the cutting head portion and the tool shank portion is performed only by the elastic connection by the elastic slit.
If the bonding force between the two is small and a large cutting load is applied during drilling, the cutting head part easily shifts or comes off,
There is a problem that the machining cost increases because the hole machining accuracy is lowered and the tool is easily damaged. Further, if the force applied to the torque transmission wall acts in a disadvantageous direction on the cutting head portion, it is likely to cause damage to the cutting head portion, and thus there is a problem in that the processing cost increases as in the above case. In view of such circumstances, an object of the present invention is to provide a throw-away drill in which the cutting head part can be easily attached and detached, can be firmly fixed, and can be prevented from being damaged.

[0004]

In order to solve the above-mentioned problems, the invention described in claim 1 is a throw-away type drill in which a cutting head portion provided with a cutting blade is detachably attached to a tool body. In, one of the cutting head portion and the tool body is provided with a fitting portion, and the other is provided with a receiving portion capable of fitting with the fitting portion, and the fitting portion is a shaft portion protruding in the axial direction. And a coupling surface provided on each of opposite side surfaces of the shaft portion, and a step portion provided in the vicinity thereof, wherein the receiving portion is provided with a concave portion into which the shaft portion is fitted, and the concave portion facing inside the concave portion. And a receiving step portion that is provided in the vicinity thereof and that engages with the step portion and transmits a rotational force. Tighten the fastening bolts from the axial direction with the receiving part and the receiving part fitted. By, characterized in that to fix the cutting head portion in the tool body. When fixing the cutting head portion to the tool body 2 in the tool body 2, the connecting surface of the cutting head portion is relatively inserted into the gap between the contact surfaces facing each other of the recess, and the pair of contact surfaces and the connecting surface are The cutting heads are relatively rotated in the direction opposite to the rotation direction of the tool body while intersecting each other, and the step portion is fitted in the receiving step portion and the connecting surface is engaged with the contact surface from the axial direction. By tightening the fastening bolt, the cutting head portion can be firmly fixed to the tool body.

Further, in the invention described in claim 2, the step portion and the receiving step portion are oriented along the outer periphery of the cutting head portion or the tool body, and the outer peripheral side thereof is oriented in the rotational direction. It is characterized in that it is arranged at an angle. With this configuration, when the tool body rotates and transmits the driving force to the cutting head portion, the driving force causes the cutting head portion to move between the step portions and the receiving step portions that are provided to face the axis. A component force directed inward in the radial direction is generated and acts on the cutting head portion in the compression direction.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of a throw-away type drill according to the present invention, and FIG. 2 is a plan view thereof. As shown in FIG. 1, in a throw-away type drill (hereinafter sometimes referred to as a drill) 1 according to the present embodiment, a tool body 2 has a substantially rod-like shape including a shank portion 3 and a blade portion 4,
At the tip of the blade portion 4, a pair of cutting blades 8 is provided on the tapered tip surface 7.
A throw-away type cutting head portion 5 having a is attached so as to be replaceable. On the outer peripheral surface 4a of the blade portion 2, two chip discharge grooves 6 and 6 and the land portion 1 adjacent to them are provided.
Numerals 0 and 10 are formed in rotational symmetry so as to face each other around the axis of rotation O of the drill body and are twisted around the axis of rotation O. An oil hole 28 is formed inside the tool main body 2 along the rotation axis O, preferably coaxially, from the base end side (lower side in the figure) of the tool main body 2 toward the cutting head portion 5. ing. The oil holes 28 are branched into a plurality (two in the present embodiment) at an intermediate position where the oil holes 28 do not reach the cutting head portion 5, and each of the branched oil holes 28a and 28a extends to the outer peripheral side and extends in the vicinity of the cutting head portion 5. The opening is formed in the oil grooves 28b, 28b provided on the outer peripheral surfaces of the portions 10, 10.

As shown in FIG. 2, in the cutting head portion 5, each intersecting ridge line portion between the tip-side wall surface facing the rotation direction of each chip discharge groove 6, 6 (indicated by an arrow R in the figure) and the tip surface 7. A pair of cutting blades 8 and 8 are formed in the. Fastening bolts 30, 30 are inserted through the tip surface 7, and are fastened to the screw holes 29, 29 (not shown) of the tool body 2 to fix the cutting head 5 to the tool body 2. The concave portions 5b and 5b form a part of the oil grooves 28b and 28b, and allow direct oil supply to the cutting portion during drilling. As shown in FIG. 1, the drill 1 having the above-described basic configuration includes a fitting portion 14 provided on the throw-away type cutting head portion 5 and a receiving portion 20 provided on the tool body 2 and described later. And are fitted to each other and can be fixed to each other.

FIG. 3 is a plan view of the cutting head portion 5, and FIG. 4 is a side view thereof. As shown in FIG. 3, the cutting head portion 5
Is provided with a pair of head lands 10a, 10a that are formed rotationally symmetrically on both sides of the rotation axis O, and a pair of concave side surfaces 6a, 6a having a substantially concave curved surface are formed adjacent to the head lands 10a, 10a. Has been formed. The head land portions 10a, 10a form part of the land portions 10, 10, and the concave side surfaces 6a, 6a form part of the chip discharge grooves 6, 6. The front end surface 7 is formed in a substantially tapered shape centering on the rotation axis O, and is provided sequentially with the pair of cutting blades 8 extending from the vicinity of the rotation axis O to the outside in the radial direction, and behind each cutting blade 8 in the rotation direction. It has a flank 11 and a thinning surface 12. Further, the head land portions 10a, 10a are formed with insertion holes 9, 9 for inserting the fastening bolts 30, 30 in the axial direction on both sides of the rotation axis O in a rotationally symmetrical manner. The arrow R in the figure indicates the direction of rotation.

As shown in FIG. 4, a fitting portion 14 for fitting with the tool main body 2 is provided on the surface (base end surface 5a) of the cutting head portion 5 opposite to the tip end surface 7. The fitting portion 14 has a shaft portion 15 which is coaxial with the rotation axis O and protrudes from the base end surface 5a in a substantially tapered shape, and an outer surface of the shaft portion 15 in the direction of the head lands 10a and 10a is a substantially truncated cone peripheral surface. It has a pair of connecting surfaces 16 and 16 formed in a shape. Head receiving portions 9a, 9a for supporting the heads of the fastening bolts 30 are formed on the inner circumferences of the insertion holes 9, 9, and the head receiving portions 9a serve as a boundary and the tip end with respect to the hole diameter on the base end face 5a side is formed. The hole diameter on the surface 7 side is wide. The end surface of the shaft portion 15 on the tool body 2 side is referred to as the lower end surface 15a.

The fitting portion 14 is also provided with a step portion 18 formed by cutting out the base end surface 5a toward the front end surface 7 side.
The step portion 18 has an inclined surface 18a extending in the radial direction for transmitting the driving force, and a thick portion 18b and a thin portion 18c located on both sides in the circumferential direction. Here, FIG.
As shown in, the thick portion 18b is located forward of the thin portion 18c in the rotational direction of the drill 1. A pair of step portions 18 are provided on the back surface of the head lands 10a, 10a, and are formed 180 ° rotationally symmetrically on both sides of the rotation axis O, respectively. In the figure, for convenience of illustration, only one of the step portions 18 is given a reference numeral. Further, the step portions 18, 18
Are arranged in a direction along the outer periphery of the cutting head portion 5 and inclined so that the outer peripheral side thereof faces the rotation direction.

FIG. 5 is a plan view of the tip portion of the tool body 2, and FIG. 6 is a side view thereof. As shown in FIG. 5, the tool body 2
A pair of main body land portions 1 formed adjacent to the chip discharge ports 6 and 6 on both sides of the rotation axis O in the blade portion 4 of the
0b and 10b are provided, and the main body land portion 10
b and 10b form the land portions 10 and 10 together with the head land portions 10a and 10a. The arrow R in the figure indicates the direction of rotation.

As shown in FIG. 6, the tip surface 2 of the tool body 2 is
In a, a receiving portion 20 for fitting the cutting head portion 5 is provided.
Is provided. The receiving portion 20 includes a recess 22 formed by cutting out the tip surface 2a of the tool body 2 toward the base end side (downward side in the drawing) of the tool body 2, and the body land portions 10b and 10b of the recess 22. The inner surface of the connecting surface 1
6 is provided with a pair of abutting surfaces 23, 23 formed in a substantially frustoconical concave surface. The bottom surface of the recess 22 is referred to as a bottom surface 22a. Further, a pair of facing areas adjacent to the contact surfaces 23, 23 are cut off by the chip discharge grooves 6, 6 to form a pair of side opening portions 22b, 22b which are open to the outside. Screw holes 29, 29 for tightening the fastening bolts 30 are formed in the main body lands 10b, 10b at positions corresponding to the insertion holes 9, 9 rotationally symmetrically on both sides of the rotation axis O. The perforations formed around the rotation axis O are centering holes for machining the tool body 2.

Further, the receiving portion 20 is formed on the tip surface 2a so as to be projectingly formed, and is fitted into the step portion 18 of the cutting head portion 5 in a concavo-convex manner so that the driving force of the tool body 2 is transmitted to the cutting head portion 5 and integrally rotated. The receiving step portion 24 is provided. This receiving step 2
Reference numeral 4 denotes an inclined surface (which may be a vertical surface) 24a extending in the radial direction for transmitting the driving force, and an upper surface portion 24b and an upper surface portion 24 located on both sides in the circumferential direction thereof and relatively projecting toward the cutting head portion 5 side.
It has the bottom face part 24c at a position lower than b. Here, as shown in FIG. 7, the upper surface portion 24b is located behind the bottom surface portion 24c in the rotational direction of the drill 1. Also,
The pair of receiving step portions 24 are the main body land portions 10b, 10
A pair is provided on the front end surface 2a of b and is formed 180 ° rotationally symmetrically on both sides of the rotation axis O, respectively. In the figure, for convenience of illustration, only one receiving step portion 24 is denoted by a reference numeral. In addition, the upper opening 22 c of the recess 22 has a receiving step portion 24.
The bottom surface 24c is at the same height as the bottom surface 24c, and the top surface portion 24b is at a position higher than this. Further, the receiving steps 24, 24 are
It is arranged in a direction along the outer periphery of the tool body 2 and inclined so that the outer peripheral side faces the rotational direction.

Here, in FIG. 5, when the minimum distance at the upper opening 22c between the pair of abutting surfaces 23, 23 having the concave curved surfaces facing each other is D1 and the minimum distance at the bottom surface 22a is D2, D1 < It becomes D2. Further, in FIG. 3, each connecting surface 16 in the base end surface 5 a of the cutting head portion 5
Is P1 and the width of each connecting surface 16 at the lower end surface 15a of the shaft portion 15 is P2, P1 <P2. Moreover, the width P1 of the connecting surface 16 is determined by the upper opening 22 of the recess 22.
The width c is set to be slightly smaller than the width D1 and the width P2 is set to be slightly smaller than the width D2. Therefore, the shaft portion 15 of the cutting head portion 5 can be inserted into and removed from the concave portion 22 with the connecting surface 16 facing forward through the space between the side opening portions 22b and 22b of the concave portion 22.

The drill 1 according to this embodiment has the above-mentioned structure. Next, a procedure for mounting the cutting head portion 5 on the tool body 2 of the drill 1 will be described. FIG. 7 is a plan view showing an intermediate stage when the cutting head portion 5 is mounted on the tool body 2, and FIG. 8 is a plan view showing a mounting completed state. First, as shown in FIG. 7, the connecting surface 16 of the shaft portion 15 of the cutting head portion 5 is directed to the side opening portion 22b of the receiving portion 20 of the tool main body 2, and the inside of the concave portion 22 is indicated by a double-headed arrow A in the figure. To insert. When the rotation axis O of the shaft portion 15 of the cutting head portion 5 and the rotation axis O of the tool body 2 substantially coincide with each other, the head land portions 10a, 10a of the cutting head portion 5 and the body land portions 10b, 10b of the tool body 2 are aligned. And are substantially orthogonal to each other, and
The pair of contact surfaces 23, 23 and the connecting surfaces 16, 16 are substantially orthogonal to each other. At this time, the pair of connecting surfaces 16 and 16 of the shaft portion 15 are respectively formed in the side opening portion 22 of the recess 22.
It is located at b and 22b.

Then, when the cutting head portion 5 is rotated with respect to the receiving portion 20 of the tool body 2 in the direction opposite to the rotation direction of the tool body 2 (indicated by arrow R'in the figure), as shown in FIG. The connecting surfaces 16 and 16 of the shaft portion 15 rotate approximately 90 ° to overlap the abutting surfaces 23 and 23 of the concave portion 22 on the inside, and are brought into surface contact and engaged. At the same time, the stepped portion 18 of the cutting head portion 5 also rotates approximately 90 °, and the inclined surface 18a thereof is joined to the inclined surface 24a of the receiving step portion 24 of the receiving portion 20 as shown in the side view. In this state, the land portions 10a, 10 of the cutting head portion 5 are
a precisely overlaps the land parts 10b, 10b of the tool body 2, and serves as the drill 1 for the chip discharge grooves 6, 6 and the land part 10,
10 and 10 are smoothly connected in a spiral shape from the tool body 2 to the cutting head portion 5 to be integrated. Finally, as shown in FIG. 9, the fastening bolts 30, 30 are inserted through the insertion holes 9, 9 and screwed into the screw holes 29, 29 to be tightened, whereby the connection surfaces 16 and the contact surfaces 23 are Further, the tool body 2 and the cutting head portion 5 are firmly fixed in a state where the step portions 18 and the receiving step portions 24 are fitted to each other. The cutting head portion 5 is attached to the drill 1 by the above procedure.

When drilling is performed using this drill 1, the driving force transmitted to the tool body 2 via the spindle shaft of a machine tool (not shown) is transferred from the receiving step 22 to the step 1
By being transmitted to 8, the cutting head unit 5 rotates. At this time, since the receiving step portion 22 and the step portion 18 are arranged in a direction along the outer periphery of the cutting head portion 5 or the tool main body 2 and inclined so that the outer peripheral side faces the rotation direction, Each step portion 18 provided so as to face the axis O
A component force directed inward in the radial direction of the cutting head portion 5 is generated between the receiving step portion 22 and the receiving step portion 22, and the other step portion 18 and the receiving step portion 22 formed rotationally symmetrically with respect to the rotation axis O.
Along with the radial component force similarly generated between them, the cutting head portion 5
Acts to compress. Therefore, compared with the case where the radial component force acts so as to pull the cutting head portion 5, strength is particularly advantageous in the case of a hard steel material such as tool steel, and the durability of the cutting head portion 5 is improved. be able to. Then, the drill 1 integrally rotates around the rotation axis O, the hole is cut in the work material by the cutting blades 8, 8, and the chips generated by the cutting blade 8 are discharged to the base end side through the chip discharging groove 6. It When the cutting edge 8 is worn or broken due to processing and needs to be replaced, the cutting head portion 5 is removed in the reverse order of the above-described mounting step, and another cutting head portion 5 is mounted in the same procedure as described above. do it.

As described above, according to the present embodiment, the cutting head portion 5 can be firmly fixed to the tool body 2,
Even when a high load is applied to the cutting head portion 5 through the cutting edge 8 during drilling with the drill 1, the cutting head portion 5 does not shift or come off, vibration is suppressed, and the drilling accuracy is precise, and the tool life is long. Can be improved. Further, since the driving force generates a component force directed inward in the radial direction of the cutting head portion 5 and acts on the cutting head portion 5 in the compression direction, the radial direction component force acts on the cutting head portion 5 in the tensile direction. It is advantageous in strength as compared with the case, and the durability of the cutting head portion 5 can be improved.

The present invention is not limited to the above embodiment, and for example, the base end surface 5a of the cutting head portion 5 is provided with the receiving portion 20 for fitting with the tool main body 2, and the tool main body 2 is provided.
A fitting portion 14 for fitting the cutting head portion 5 may be provided on the tip surface 2a of the.

[0020]

As described above, in the drill according to the present invention, the fitting portion of the cutting head portion has a shaft portion projecting in the axial direction, and a connecting surface provided on each of opposite side surfaces of the shaft portion. The receiving portion of the tool body is provided with a step portion provided in the vicinity thereof, and the receiving portion of the tool body is in contact with a recess for engaging the shaft portion and for engaging with respective connecting surfaces of the shaft portion that are formed facing each other in the recess portion. A surface, and a receiving step portion that is provided in the vicinity of the receiving step portion and that fits into the step portion and transmits a rotational force. With the fitting portion and the receiving portion fitted together, the fastening bolt from the axial direction. Since the cutting head part is fixed to the tool body by tightening, the connecting surface of the cutting head part is inserted into the gap between the contact surfaces in the recess and the tool head is rotated in the direction opposite to the rotation direction of the tool body. And tighten the fastening bolts from the axial direction, De unit is firmly fixed, by performing a high-precision processing by suppressing vibration without both or displaced to the drilling or the like long life can be obtained.

Further, in the throw-away drill according to the present invention, the step portion and the receiving step portion are oriented along the outer periphery of the cutting head portion or the tool body, and the outer peripheral side thereof is oriented in the rotational direction. Since they are arranged so as to be inclined, a driving force produces a component force toward the inside of the cutting head in the radial direction, and acts on the cutting head in the compression direction. It is advantageous in strength as compared with the case of acting in the direction, and the durability of the cutting head portion can be improved.

[Brief description of drawings]

FIG. 1 is a side view of a throw-away drill according to an embodiment of the present invention.

FIG. 2 is a plan view of the throw-away drill according to the embodiment of the present invention.

FIG. 3 is a plan view of a cutting head portion according to the embodiment of the present invention.

FIG. 4 is a side view of the cutting head portion according to the embodiment of the present invention.

FIG. 5 is a plan view of the tip portion of the tool body according to the embodiment of the present invention.

FIG. 6 is a side view of the tip portion of the tool body according to the embodiment of the present invention.

FIG. 7 is a plan view showing an intermediate stage in mounting the cutting head portion on the tool body.

FIG. 8 is a plan view showing a state in which the cutting head is completely attached to the tool body.

FIG. 9 is a side view showing a state in which the cutting head is completely attached to the tool body.

[Explanation of symbols]

1 Throw-away drill 2 Tool body 5 Cutting head 6 Chip discharge groove 8 cutting edges 14 Fitting part 15 Shaft 16 Connecting surface 18 Step 20 Receiver 22 recess 23 Contact surface 24 Receiving step 30 fastening bolts

Claims (2)

[Claims] 1. A throw-away drill in which a cutting head portion having a cutting edge is removably attached to a tool body, wherein one of the cutting head portion and the tool body is provided with a fitting portion and the other is provided. A receiving portion that can be fitted to the fitting portion is provided, and the fitting portion includes a shaft portion that projects in the axial direction, a connecting surface that is provided on each of opposite side surfaces of the shaft portion, and the vicinity thereof. A step portion provided, the receiving portion, a recess for fitting the shaft portion, and a contact surface that is formed in the recess so as to be engaged with each coupling surface of the shaft portion, And a receiving step portion that is provided in the vicinity thereof and that fits into the step portion and transmits a rotational force. Tighten the fastening bolt in the axial direction with the fitting portion and the receiving portion fitted together. By fixing the cutting head portion to the tool body, Throw-away drill. 2. The step portion and the receiving step portion are arranged in a direction along the outer periphery of the cutting head portion or the tool body, and are inclined so that the outer peripheral side thereof faces the rotation direction. The throw-away type drill according to claim 1.