JP3818196B2 - Throw-away drill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a throw-away drill that can replace a cutting head portion having a cutting edge with a tool body.
[0002]
[Prior art]
Conventionally, as a throw-away type drill in which a cutting head portion having a cutting edge can be mounted on a tool body in a replaceable manner, for example, there is one described in Utility Model Registration No. 3054444.
This throw-away type drill has an elastic slit in the tool shank at the connecting part between the cutting head part and the tool shank, which is the tip end side region of the drill, and a pair of concave fixings for connection facing both sides of the elastic slit. A wall and a pair of torque transmission walls that transmit torque to the cutting head portion are formed, respectively, and the cutting head portion includes a pair of convex fixed walls that engage with the fixed wall of the tool shank, and a torque transmission wall of the tool shank. And a pair of torque conducting walls to be fitted. The minimum interval between the opposing concave fixed walls is set wider than the width of the convex fixed walls.
And when connecting the cutting head part to the tool shank, both the fixing walls are coaxially orthogonally crossed so that the convex fixing wall of the cutting head part passes through the gap of the concave fixing wall of the tool shank, and then the cutting head part Is rotated in the direction opposite to the rotation direction of the tool body, the torque transmission wall of the cutting head portion comes into contact with the torque transmission wall of the tool shank portion, and the convex fixed wall and the concave fixed wall are coupled. The two fixed walls are connected while elastically deforming and expanding the elastic slit of the tool body, whereby the cutting head portion and the tool shank are elastically connected.
[0003]
[Problems to be solved by the invention]
However, in such a structure, the cutting head part and the tool shank part are coupled only by elastic coupling by an elastic slit, so the coupling force between the two is small, and if a large cutting load is applied during drilling, the cutting head There is a problem that the part is easily displaced or detached, the hole machining accuracy is lowered, or the tool is easily damaged, leading to an increase in machining cost.
In view of such circumstances, an object of the present invention is to provide a throw-away drill that is easy to attach and detach the cutting head portion and can be firmly fixed.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is a throwaway drill in which a cutting head portion provided with a cutting blade is detachably attached to a tool body, wherein the cutting head portion or the tool One of the main bodies is provided with a key portion that protrudes axially over a portion extending in the radial direction to the outer peripheral surface, and on the other side, a key groove into which the key portion can be fitted extends over the portion reaching the outer peripheral surface. A centering convex part protruding on an axis is provided on one of the key part or the key groove, and a centering concave part that can be fitted to the centering convex part is provided on the other side. Fastening from the axial direction with the convex part and the centering concave part fitted to match the rotation axis of the tool body and the cutting head part , and with the key part and the key groove fitted By tightening the bolt, Characterized by fixing the serial cutting head portion. With this configuration, when the cutting head portion is fixed to the tool body, the rotation axis of the tool body and the cutting head portion is matched by fitting the centering convex portion and the centering concave portion, and the key The tool body and the cutting head part are fixed in the rotational direction by fitting the part and the key groove, and the cutting head part is mechanically firmly fixed to the tool body by tightening the fastening bolt from the axial direction in this state. It becomes possible to fix to.
[0005]
DETAILED DESCRIPTION OF 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 drill according to the present invention, and FIG. 2 is a plan view thereof.
As shown in FIG. 1, a throw-away type drill (hereinafter sometimes referred to as a drill) 1 according to the present embodiment has a tool body 2 having a substantially bar shape including a shank portion 3 and a blade portion 4. A throwaway type cutting head portion 5 having a pair of cutting edges 8 on a tapered tip surface 7 is replaceably attached to the tip of the portion 4.
On the outer peripheral surface of the blade portion 4, two chip discharge grooves 6, 6 and land portions 10, 10 adjacent thereto are formed rotationally symmetrically about the rotation axis O of the drill body, and around the rotation axis O. It is twisted.
An oil hole 28 is formed in the tool body 2 along the rotation axis O, preferably coaxially, from the base end side (the lower side in the drawing) of the tool body 2 toward the cutting head portion 5. ing. The oil holes 28 are branched into a plurality of (two in the present embodiment) at a midway position that does not reach the cutting head portion 5, and each of the branched oil holes 28 a, 28 a extends to the outer peripheral side and is near the cutting head portion 5. The land portions 10, 10 are open to oil grooves 28b, 28b provided on the outer peripheral surface.
[0006]
As shown in FIG. 2, in the cutting head unit 5, a pair of crossed ridge lines between the tip wall surface and the tip surface 7 facing the rotation direction (indicated by an arrow R in the figure) of each chip discharge groove 6, 6 Cutting blades 8 and 8 are formed.
The concave surface portions 5b and 5b constitute 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 is detachably fixed to the tool body 2 by fastening bolts 30, 30 provided with a throw-away type cutting head portion 5 provided in the axial direction. Yes.
[0007]
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 land portions 10a, 10a that are formed rotationally symmetrically about the rotation axis O, and is substantially concave adjacent to the head land portions 10a, 10a. A pair of curved concave side surfaces 6a, 6a is formed. The head land portions 10a, 10a constitute part of the land portions 10, 10, and the concave side surfaces 6a, 6a constitute part of the chip discharge grooves 6, 6.
The front end surface 7 is formed in a substantially tapered shape with the rotation axis O as the center, and is sequentially provided behind the pair of cutting blades 8 and 8 extending radially outward from the vicinity of the rotation axis O and the rotation direction of each cutting blade 8. It has a flank 11 and a thinning surface 12.
Further, insertion holes 9 and 9 for inserting the fastening bolts 30 and 30 in the axial direction are formed in the head land portions 10a and 10a in a rotationally symmetrical manner with the rotation axis O as the center. In the figure, an arrow R indicates the direction of rotation.
[0008]
And as shown in FIG. 4, the key part 18 which protrudes from the base end surface 5a is provided in the surface (base end surface 5a) on the opposite side to the front end surface 7 of the cutting head part 5. As shown in FIG. As shown in FIG. 3, the key portion 18 is provided over a portion extending in the radial direction of the cutting head portion 5 and reaching the outer peripheral surface. That is, the key portion 18 is formed up to a portion reaching the outer peripheral surface of the cutting head portion 5.
The insertion holes 9, 9 are provided at the installation site of the key portion 18, and penetrate the key portion 18 in the axial direction.
On the bottom surface 18a of the key portion 18, a shaft portion 15 (a centering convex portion) that protrudes coaxially with the rotation axis O is formed.
In each of the insertion holes 9 and 9, head receiving portions 9 a and 9 a for supporting the heads of the fastening bolts 30 and 30 inserted from the front end surface 7 side are formed.
[0009]
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 blade portion 4 of the tool body 2 is provided with a pair of land portions 10 and 10 that are formed symmetrically about the rotation axis O adjacent to the chip discharge grooves 6 and 6. ing.
In the land portions 10, 10, key grooves 24 that can be fitted with the key portions 18 are provided in the radial direction of the tool main body 2 and extending to the outer peripheral surface. Further, screw holes 29 and 29 for fastening the fastening bolts 30 and 30 are formed in a rotationally symmetrical manner about the rotation axis O at positions corresponding to the insertion holes 9 and 9. In the figure, an arrow R indicates the direction of rotation.
[0010]
As shown in FIG. 6, the key groove 24 is formed from the distal end surface 2a of the tool body 2 to the base end side (lower side in the figure), and the bottom surface 24a has screw portions 29, 29, And the recessed part 22 (centering recessed part) which fits the axial part 15 of the cutting head part 5 is formed in the base end side of the tool main body 2, and the rotation axis O and the same axis | shaft.
[0011]
The drill 1 according to the present embodiment has the above-described configuration. Next, a procedure for mounting the cutting head portion 5 on the tool body 2 of the drill 1 will be described.
First, the cutting head portion is mounted on the tool body 2 so that the respective rotation axes O substantially coincide with each other, and the shaft portion 15 provided on the cutting head portion 5 is attached to the tool body 2 as shown in FIGS. The key portion 18 is fitted into the key groove 24 while being fitted into the provided recess 22.
In this state, the head land portions 10 a, 10 a of the cutting head portion 5 are precisely overlapped with the land portions 10, 10 of the tool body 2, and the chip discharge grooves 6, 6 and the land portions 10, 10 form the drill 1 from the tool body 2. The cutting head portion 5 is smoothly connected in a spiral manner and integrated.
Then, the fastening bolts 30 and 30 are attached so as to interpose the cutting head portion 5, and are fastened to the tool body 2, whereby the cutting head portion 5 is mechanically firmly fixed to the tool body 2.
The cutting head unit 5 is attached to the tool body 2 by the above procedure.
[0012]
When drilling is performed using the drill 1, the driving force transmitted to the tool body 2 via a spindle shaft of a machine tool (not shown) is transmitted to the cutting head portion 5 via the key groove 24 and the key portion 18. Thus, the drill 1 rotates integrally around the rotation axis O.
Then, the workpiece is drilled by the cutting edges 8 and 8, and the chips generated by the cutting edge 8 are discharged to the base end side through the chip discharge groove 6.
When the cutting edge 8 is worn or missing due to processing and needs to be replaced, the cutting head portion 5 is removed in the reverse procedure of the above mounting step, and the other cutting head portion 5 is mounted in the same procedure as described above. That's fine.
[0013]
As described above, according to the present embodiment, the cutting head unit 5 can be mechanically firmly fixed to the tool body 2, and a high load is applied to the cutting head unit 5 through the cutting blade 8 during drilling with the drill 1. Even if it is applied, the cutting head portion 5 is not displaced or detached, so that the vibration can be suppressed and the hole machining accuracy is precise, and the tool life can be improved.
[0014]
The present invention is not limited to the above embodiment, and for example, the key groove 24 may be provided on the base end surface 5a of the cutting head portion 5 and the key portion 18 may be provided on the distal end surface 2a of the tool body 2. In this case, since the protrusion from the base end surface 5a of the cutting head part 5 is eliminated, the yield of the material of the cutting head part 5 is improved, and the cost can be reduced.
[0015]
【The invention's effect】
As described above, in the drill according to the present invention, one of the cutting head portion and the tool body is provided with a key portion that protrudes on the axial line over a portion extending in the radial direction to the outer peripheral surface, and the key portion on the other side. A key groove that can be fitted with the centering convex part is provided on one of the key part or the key groove, and a centering concave part that can be fitted with the centering convex part is provided on the other side. The cutting head portion is fixed to the tool body by fitting the centering convex portion and the centering concave portion and tightening the fastening bolt in a state where the key portion and the key groove are fitted. Therefore, when the centering convex part and the centering concave part are fitted, and the fastening bolt is tightened from the axial direction with the key part and the key groove fitted, the cutting head part is mechanically firmly fixed to the tool body. The two may be misaligned when drilling. Long life can be obtained by performing a high-precision processing by suppressing vibration without.
[Brief description of the 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 a throw-away drill according to an 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 in the embodiment of the present invention.
FIG. 5 is a plan view of the tip portion of the tool body in the embodiment of the present invention.
FIG. 6 is a side view of the tip portion of the tool body in the embodiment of the present invention.
FIG. 7 is a plan view showing a state in which the cutting head portion is mounted on the tool body.
FIG. 8 is a side view showing a state in which a cutting head is mounted on the tool body.
[Explanation of symbols]
1 Throw Away Drill 2 Tool Body 8 Cutting Head 15 Shaft (Centering Convex)
18 Key part 22 Recess (Centering recess)
24 Keyway 30 Fastening bolt

Claims (1)

In the throw-away drill, in which the cutting head provided with the cutting blade is detachably attached to the tool body,
One of the cutting head or the tool main body is provided with a key portion that protrudes on the axial line over a portion extending in the radial direction to the outer peripheral surface, and the other has a key groove into which the key portion can be fitted. It is provided over the part that reaches the outer peripheral surface ,
One of the key part or the key groove is provided with a centering convex part protruding on the axis, and the other is provided with a centering concave part that can be fitted to the centering convex part,
The centering convex portion and the centering concave portion are fitted to match the rotation axis of the tool body and the cutting head portion , and the key portion and the key groove are fitted to each other. A throw-away drill, wherein the cutting head portion is fixed to the tool body by tightening a fastening bolt from a direction.

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